Scalable and Tunable Carbide-Phosphide Composite Catalyst System for the Thermochemical Conversion of Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Regmi, Yagya; Rogers, Bridget; Labbe, Nicole

We have prepared composite materials of hexagonal nickel phosphide and molybdenum carbide (Mo2C) utilizing a simple and scalable two-stage synthesis method comprised of carbothermic reduction followed by hydrothermal incubation. We observe the monophasic hexagonal phosphide Ni2P in the composite at low phosphide-to-carbide (P:C) ratios. Upon increasing the proportion of P:C, the carbide surface becomes saturated, and we detect the emergence of a second hexagonal nickel phosphide phase (Ni5P4) upon annealing. We demonstrate that vapor-phase upgrading (VPU) of whole biomass via catalytic fast pyrolysis is achievable using the composite material as a catalyst, and we monitor the resulting product slates usingmore » pyrolysis gas chromatography/mass spectrometry. Our analysis of the product vapors indicates that variation of the P:C molar ratio in the composite material affords product slates of varying complexity and composition, which is indicated by the number of products and their relative proportions in the product slate. Our results demonstrate that targeted vapor product composition can be obtained, which can potentially be utilized to tune the composition of the bio-oil downstream.« less

Scalable and Tunable Carbide-Phosphide Composite Catalyst System for the Thermochemical Conversion of Biomass

DOE PAGES

Regmi, Yagya; Rogers, Bridget; Labbe, Nicole; ...

2017-07-13

We have prepared composite materials of hexagonal nickel phosphide and molybdenum carbide (Mo2C) utilizing a simple and scalable two-stage synthesis method comprised of carbothermic reduction followed by hydrothermal incubation. We observe the monophasic hexagonal phosphide Ni2P in the composite at low phosphide-to-carbide (P:C) ratios. Upon increasing the proportion of P:C, the carbide surface becomes saturated, and we detect the emergence of a second hexagonal nickel phosphide phase (Ni5P4) upon annealing. We demonstrate that vapor-phase upgrading (VPU) of whole biomass via catalytic fast pyrolysis is achievable using the composite material as a catalyst, and we monitor the resulting product slates usingmore » pyrolysis gas chromatography/mass spectrometry. Our analysis of the product vapors indicates that variation of the P:C molar ratio in the composite material affords product slates of varying complexity and composition, which is indicated by the number of products and their relative proportions in the product slate. Our results demonstrate that targeted vapor product composition can be obtained, which can potentially be utilized to tune the composition of the bio-oil downstream.« less

Fabrication of hierarchical CoP nanosheet@microwire arrays via space-confined phosphidation toward high-efficiency water oxidation electrocatalysis under alkaline conditions.

PubMed

Ji, Xuqiang; Zhang, Rong; Shi, Xifeng; Asiri, Abdullah M; Zheng, Baozhan; Sun, Xuping

2018-05-03

In spite of recent advances in the synthesis of transition metal phosphide nanostructures, the simple fabrication of hierarchical arrays with more accessible active sites still remains a great challenge. In this Communication, we report a space-confined phosphidation strategy toward developing hierarchical CoP nanosheet@microwire arrays on nickel foam (CoP NS@MW/NF) using a Co(H2PO4)2·2H3PO4 microwire array as the precursor. The thermally stable nature of the anion in the precursor is key to hierarchical nanostructure formation. When used as a 3D electrode for water oxidation electrocatalysis, such CoP NS@MW/NF needs an overpotential as low as 296 mV to drive a geometrical catalytic current density of 100 mA cm-2 in 1.0 M KOH, outperforming all reported Co phosphide catalysts in alkaline media. This catalyst also shows superior long-term electrochemical durability, maintaining its activity for at least 65 h. This study offers us a general method for facile preparation of hierarchical arrays for applications.

Synthesis and x-ray characterization of cobalt phosphide (Co₂P) nanorods for the oxygen reduction reaction

DOE PAGES

Doan-Nguyen, Vicky V.T.; Su, Dong; Zhang, Sen; ...

2015-07-14

Low temperature fuel cells are clean, effective alternative fuel conversion technology. Oxygen reduction reaction (ORR) at the fuel cell cathode has required Pt as the electrocatalyst for high activity and selectivity of the four-electron reaction pathway. Targeting a less expensive, earth abundant alternative, we have developed the synthesis of cobalt phosphide (Co₂P) nanorods for ORR. Characterization techniques that include total X-ray scattering and extended X-ray absorption fine structure revealed a deviation of the nanorods from bulk crystal structure with a contraction along the b orthorhombic lattice parameter. The carbon supported nanorods have comparable activity but are remarkably more stable thanmore » conventional Pt catalysts for the oxygen reduction reaction in alkaline environments.« less

Synthesis and catalytic activity of the metastable phase of gold phosphide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernando, Deshani; Nigro, Toni A. E.; Dyer, I. D.

Recently, transition metal phosphides have found new applications as catalysts for the hydrogen evolution reaction that has generated an impetus to synthesize these materials at the nanoscale. In this work, Au2P3 was synthesized utilizing the high temperature decomposition of tri-n-octylphosphine as a source of elemental phosphorous. Gold nanorods were used as morphological templates with the aim of controlling the shape and size of the resulting gold phosphide particles. We demonstrate that the surface capping ligand of the gold nanoparticle precursors can influence the purity and extent to which the gold phosphide phase will form. Gold nanorods functionalized with 1-dodecanethiol undergomore » digestive ripening to produce discrete spherical particles that exhibit reduced reactivity towards phosphorous, resulting in low yields of the gold phosphide. In contrast, gold phosphide was obtained as a phase pure product when cetyltrimethylammonium bromide functionalized gold nanorods are used instead. The Au2P3 nanoparticles exhibited higher activity than polycrystalline gold towards the hydrogen evolution reaction.« less

Trends in activity for the oxygen evolution reaction on transition metal (M = Fe, Co, Ni) phosphide pre-catalysts† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc05033j

PubMed Central

Xu, Junyuan; Li, Junjie; Xiong, Dehua; Zhang, Bingsen; Liu, Yuefeng; Wu, Kuang-Hsu; Amorim, Isilda; Li, Wei

2018-01-01

Transition metal phosphides (TMPs) have recently emerged as a new class of pre-catalysts that can efficiently catalyze the oxygen evolution reaction (OER). However, how the OER activity of TMPs varies with the catalyst composition has not been systematically explored. Here, we report the alkaline OER electrolysis of a series of nanoparticulate phosphides containing different equimolar metal (M = Fe, Co, Ni) components. Notable trends in OER activity are observed, following the order of FeP < NiP < CoP < FeNiP < FeCoP < CoNiP < FeCoNiP, which indicate that the introduction of a secondary metal(s) to a mono-metallic TMP substantially boosts the OER performance. We ascribe the promotional effect to the enhanced oxidizing power of bi- and tri-metallic TMPs that can facilitate the formation of MOH and chemical adsorption of OH– groups, which are the rate-limiting steps for these catalysts according to our Tafel analysis. Remarkably, the tri-metallic FeCoNiP pre-catalyst exhibits exceptionally high apparent and intrinsic OER activities, requiring only 200 mV to deliver 10 mA cm–2 and showing a high turnover frequency (TOF) of ≥0.94 s–1 at the overpotential of 350 mV. PMID:29780476

MOF-Derived Ultrathin Cobalt Phosphide Nanosheets as Efficient Bifunctional Hydrogen Evolution Reaction and Oxygen Evolution Reaction Electrocatalysts

PubMed Central

Li, Hong; Ke, Fei; Zhu, Junfa

2018-01-01

The development of a highly efficient and stable bifunctional electrocatalyst for water splitting is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a novel bifunctional catalyst consisting of 2D transition-metal phosphide nanosheets with abundant reactive sites templated by Co-centered metal−organic framework nanosheets, denoted as CoP-NS/C, has been developed through a facile one-step low-temperature phosphidation process. The as-prepared CoP-NS/C has large specific surface area and ultrathin nanosheets morphology providing rich catalytic active sites. It shows excellent electrocatalytic performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic and alkaline media, with the Tafel slopes of 59 and 64 mV/dec and a current density of 10 mA/cm2 at the overpotentials of 140 and 292 mV, respectively, which are remarkably superior to those of CoP/C, CoP particles, and comparable to those of commercial noble-metal catalysts. In addition, the CoP-NS/C also shows good durability after a long-term test. PMID:29414838

High-Performance Rh 2 P Electrocatalyst for Efficient Water Splitting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Haohong; Li, Dongguo; Tang, Yan

2017-04-05

Search for active, stable and cost-efficient electrocatalysts for hydrogen production via water splitting could make substantial impact to the energy technologies that do not rely on fossil fuels. Here we report the synthesis of rhodium phosphide electrocatalyst with low metal loading in the form of nanocubes (NCs) dispersed in high surface area carbon (Rh2P/C) by a facile solvo-thermal approach. The Rh2P/C NCs exhibit remarkable performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to Rh/C and Pt/C catalysts. The atomic structure of the rhodium phosphide nanocubes was directly observed by annular dark-field scanning transmission electron microscopy (ADF-STEM),more » which revealed phosphorous-rich outermost atomic layer. Combined experimental and computational studies suggest that surface phosphorous plays crucial role in determining the robust catalyst properties.« less

Metal phosphide catalysts and methods for making the same and uses thereof

DOEpatents

Habas, Susan Ellen; Wang, Jun; Ruddy, Daniel A.; Baddour, Frederick Raymond Gabriel; Schaidle, Joshua

2017-05-02

The present disclosure relates to a method that includes heating a mixture that includes a metal phenylphosphine-containing precursor that includes at least one of Mo(PPh.sub.3).sub.2(CO).sub.4, Pd(PPh.sub.3).sub.4, Ru(PPh.sub.3).sub.3Cl.sub.2, Ru(PPh.sub.3).sub.2(CO).sub.2Cl.sub.2, Co(PPh.sub.3)(CO).sub.2(NO), and/or Rh(PPh.sub.3).sub.2(CO)Cl, a surfactant, and a solvent. The heating is to a target temperature to form a heated mixture containing a metal phosphide nanoparticle that includes at least one of MoP, Ru.sub.2P, Co.sub.2P, Rh.sub.2P, and/or Pd.sub.3P, and the metal phosphide nanoparticle is not hollow.

Highly Efficient and Robust Nickel Phosphides as Bifunctional Electrocatalysts for Overall Water-Splitting.

PubMed

Li, Jiayuan; Li, Jing; Zhou, Xuemei; Xia, Zhaoming; Gao, Wei; Ma, Yuanyuan; Qu, Yongquan

2016-05-04

To search for the efficient non-noble metal based and/or earth-abundant electrocatalysts for overall water-splitting is critical to promote the clean-energy technologies for hydrogen economy. Herein, we report nickel phosphide (NixPy) catalysts with the controllable phases as the efficient bifunctional catalysts for water electrolysis. The phases of NixPy were determined by the temperatures of the solid-phase reaction between the ultrathin Ni(OH)2 plates and NaH2PO2·H2O. The NixPy with the richest Ni5P4 phase synthesized at 325 °C (NixPy-325) delivered efficient and robust catalytic performance for hydrogen evolution reaction (HER) in the electrolytes with a wide pH range. The NixPy-325 catalysts also exhibited a remarkable performance for oxygen evolution reaction (OER) in a strong alkaline electrolyte (1.0 M KOH) due to the formation of surface NiOOH species. Furthermore, the bifunctional NixPy-325 catalysts enabled a highly performed overall water-splitting with ∼100% Faradaic efficiency in 1.0 M KOH electrolyte, in which a low applied external potential of 1.57 V led to a stabilized catalytic current density of 10 mA/cm(2) over 60 h.

Synergy in Lignin Upgrading by a Combination of Cu-Based Mixed Oxide and Ni-Phosphide Catalysts in Supercritical Ethanol

PubMed Central

2017-01-01

The depolymerization of lignin to bioaromatics usually requires a hydrodeoxygenation (HDO) step to lower the oxygen content. A mixed Cu–Mg–Al oxide (CuMgAlOx) is an effective catalyst for the depolymerization of lignin in supercritical ethanol. We explored the use of Ni-based cocatalysts, i.e. Ni/SiO2, Ni2P/SiO2, and Ni/ASA (ASA = amorphous silica alumina), with the aim of combining lignin depolymerization and HDO in a single reaction step. While the silica-supported catalysts were themselves hardly active in lignin upgrading, Ni/ASA displayed comparable lignin monomer yield as CuMgAlOx. A drawback of using an acidic support is extensive dehydration of the ethanol solvent. Instead, combining CuMgAlOx with Ni/SiO2 and especially Ni2P/SiO2 proved to be effective in increasing the lignin monomer yield, while at the same time reducing the oxygen content of the products. With Ni2P/SiO2, the lignin monomer yield was 53 wt %, leading to nearly complete deoxygenation of the aromatic products. PMID:28405528

Synergy in Lignin Upgrading by a Combination of Cu-Based Mixed Oxide and Ni-Phosphide Catalysts in Supercritical Ethanol.

PubMed

Korányi, Tamás I; Huang, Xiaoming; Coumans, Alessandro E; Hensen, Emiel J M

2017-04-03

The depolymerization of lignin to bioaromatics usually requires a hydrodeoxygenation (HDO) step to lower the oxygen content. A mixed Cu-Mg-Al oxide (CuMgAlO x ) is an effective catalyst for the depolymerization of lignin in supercritical ethanol. We explored the use of Ni-based cocatalysts, i.e. Ni/SiO 2 , Ni 2 P/SiO 2 , and Ni/ASA (ASA = amorphous silica alumina), with the aim of combining lignin depolymerization and HDO in a single reaction step. While the silica-supported catalysts were themselves hardly active in lignin upgrading, Ni/ASA displayed comparable lignin monomer yield as CuMgAlO x . A drawback of using an acidic support is extensive dehydration of the ethanol solvent. Instead, combining CuMgAlO x with Ni/SiO 2 and especially Ni 2 P/SiO 2 proved to be effective in increasing the lignin monomer yield, while at the same time reducing the oxygen content of the products. With Ni 2 P/SiO 2 , the lignin monomer yield was 53 wt %, leading to nearly complete deoxygenation of the aromatic products.

Bifunctional catalysts for upgrading of biomass-derived oxygenates: A review

DOE PAGES

Robinson, Allison M.; Hensley, Jesse E.; Medlin, J. Will

2016-06-21

Deoxygenation is an important reaction in the conversion of biomass-derived oxygenates to fuels and chemicals. A key route for biomass refining involves the production of pyrolysis oil through rapid heating of the raw biomass feedstock. Pyrolysis oil as produced is highly oxygenated, so the feasibility of this approach depends in large part on the ability to selectively deoxygenate pyrolysis oil components to create a stream of high-value finished products. Identification of catalytic materials that are active and selective for deoxygenation of pyrolysis oil components has therefore represented a major research area. One catalyst is rarely capable of performing the differentmore » types of elementary reaction steps required to deoxygenate biomass-derived compounds. For this reason, considerable attention has been placed on bifunctional catalysts, where two different active materials are used to provide catalytic sites for diverse reaction steps. Here, we review recent trends in the development of catalysts, with a focus on catalysts for which a bifunctional effect has been proposed. We summarize recent studies of hydrodeoxygenation (HDO) of pyrolysis oil and model compounds for a range of materials, including supported metal and bimetallic catalysts as well as transition-metal oxides, sulfides, carbides, nitrides, and phosphides. Particular emphasis is placed on how catalyst structure can be related to performance via molecular-level mechanisms. Finally, these studies demonstrate the importance of catalyst bifunctionality, with each class of materials requiring hydrogenation and C-O scission sites to perform HDO at reasonable rates.« less

Effects of Polyethylene Glycol and Citric Acid on Preparation and Hydrodechlorination Activity of Molybdenum Phosphide

NASA Astrophysics Data System (ADS)

Liu, Xiaomeng; Lu, Shaoxiang; Xu, Hanghui; Ren, Lili

2018-07-01

Molybdenum phosphide (MoP), modified by polyethylene glycol (PEG) and citric acid (CA), exhibited 2 to 3 times superior activity than the MoP modified by CA alone. And the optimal activity temperature was reduced from 500 to 450oC. The catalyst was fully characterized by a variety of techniques including X-ray diffraction (XRD), N2 adsorption-desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results showed that the addition of PEG and CA increased the surface area of MoP and decreased the particle size of MoP. Furthermore, the reaction mechanism also has been discussed by combining the activity data and characterization results.

Supported black phosphorus nanosheets as hydrogen-evolving photocatalyst achieving 5.4% energy conversion efficiency at 353 K.

PubMed

Tian, Bin; Tian, Bining; Smith, Bethany; Scott, M C; Hua, Ruinian; Lei, Qin; Tian, Yue

2018-04-11

Solar-driven water splitting using powdered catalysts is considered as the most economical means for hydrogen generation. However, four-electron-driven oxidation half-reaction showing slow kinetics, accompanying with insufficient light absorption and rapid carrier combination in photocatalysts leads to low solar-to-hydrogen energy conversion efficiency. Here, we report amorphous cobalt phosphide (Co-P)-supported black phosphorus nanosheets employed as photocatalysts can simultaneously address these issues. The nanosheets exhibit robust hydrogen evolution from pure water (pH = 6.8) without bias and hole scavengers, achieving an apparent quantum efficiency of 42.55% at 430 nm and energy conversion efficiency of over 5.4% at 353 K. This photocatalytic activity is attributed to extremely efficient utilization of solar energy (~75% of solar energy) by black phosphorus nanosheets and high-carrier separation efficiency by amorphous Co-P. The hybrid material design realizes efficient solar-to-chemical energy conversion in suspension, demonstrating the potential of black phosphorus-based materials as catalysts for solar hydrogen production.

Synthesis and catalytic activity of the metastable phase of gold phosphide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernando, Deshani; Nigro, Toni A.E.; Dyer, I.D.

Recently, transition metal phosphides have found new applications as catalysts for the hydrogen evolution reaction that has generated an impetus to synthesize these materials at the nanoscale. In this work, Au{sub 2}P{sub 3} was synthesized utilizing the high temperature decomposition of tri-n-octylphosphine as a source of elemental phosphorous. Gold nanorods were used as morphological templates with the aim of controlling the shape and size of the resulting gold phosphide particles. We demonstrate that the surface capping ligand of the gold nanoparticle precursors can influence the purity and extent to which the gold phosphide phase will form. Gold nanorods functionalized withmore » 1-dodecanethiol undergo digestive ripening to produce discrete spherical particles that exhibit reduced reactivity towards phosphorous, resulting in low yields of the gold phosphide. In contrast, gold phosphide was obtained as a phase pure product when cetyltrimethylammonium bromide functionalized gold nanorods are used instead. The Au{sub 2}P{sub 3} nanoparticles exhibited higher activity than polycrystalline gold towards the hydrogen evolution reaction. - Graphical abstract: Au{sub 2}P{sub 3} was synthesized utilizing the high temperature decomposition of tri-n-octylphosphine as a source of elemental phosphorous and gold nanoparticles as reactants. We demonstrate that the surface capping ligand of the gold nanoparticle precursors influence the purity and extent to which the Au{sub 2}P{sub 3} phase will form. Gold nanorods functionalized with 1-dodecanethiol undergo digestive ripening to produce discrete spherical particles that exhibit reduced reactivity towards phosphorous, resulting in low yields of the gold phosphide. In contrast, gold phosphide was obtained as a phase pure product when cetyltrimethylammonium bromide functionalized gold nanoparticles are used instead. The Au{sub 2}P{sub 3} nanoparticles exhibited higher activity than polycrystalline gold towards the hydrogen evolution reaction. - Highlights: • The surface chemistry of gold affects the synthetic yields of Au{sub 2}P{sub 3}. • Imaging of Au{sub 2}P{sub 3} with transmission electron microscopy results in decomposition. • Au{sub 2}P{sub 3} nanoparticles exhibit activity towards the hydrogen evolution reaction.« less

MXP(M = Co/Ni)@carbon core-shell nanoparticles embedded in 3D cross-linked graphene aerogel derived from seaweed biomass for hydrogen evolution reaction.

PubMed

Zhao, Wentong; Lu, Xiaoqing; Selvaraj, Manickam; Wei, Wei; Jiang, Zhifeng; Ullah, Nabi; Liu, Jie; Xie, Jimin

2018-05-24

Low-cost electrocatalysts play an important role in the hydrogen evolution reaction (HER). Particularly, transition metal phosphides (TMPs) are widely applied in the development of HER electrocatalysts. To improve the poor electrochemical reaction kinetics of HER, we introduce a facile way to synthesize carbon core-shell materials containing cobalt phosphide nanoparticles embedded in different graphene aerogels (GAs) (CoP@C-NPs/GA-x (x = 5, 10 and 20)) using seaweed biomass as precursors. The synthesized CoP@C-NPs/GA-5 exhibits efficient catalytic activity with small overpotentials of 120 and 225 mV at current densities of 10 mA cm-2, along with the low Tafel slopes of 57 and 66 mV dec-1, for HER in acidic and alkaline electrolytes, respectively. Compared with carbon aerogel (CA) containing cobalt phosphide nanoparticles (CoP-NPs@CA), the stability of CoP@C-NPs/GA-5 coated with carbon-shells (∼0.8 nm) was significantly improved in acidic electrolytes. We also prepared carbon core-shell materials containing nickel phosphide nanoparticles embedded in GA (Ni2P@C-NPs/GA) to further expand this synthetic route. The graphene-Ni2P@C aerogel shows a similar morphology and better catalytic activity for HER in acidic and alkaline electrolytes. In this work, the robust three-dimensional (3D) GA matrix with abundant open pores and large surface area provides unblocked channels for electrolyte contact and electronic transfer and enables very close contact between the catalyst and electrolyte. The MxP@C core-shell structure prevents the inactivation of MxP NPs during HER processes, and the thin graphene oxide (GO) layers and 3D CA together build up a 3D conductive matrix, which not only adjusts the volume expansion of MxP NPs as well as preventing their aggregation, but also provides a 3D conductive pathway for rapid charge transfer processes. The present synthetic strategy for phosphides via in situ phosphorization with 3D GA can be extended to other novel high-performance catalysts. The simple synthesis and efficient catalytic activity of MXP@C-NPs/GA indicate good application prospects in HER.

Surface-oxidized cobalt phosphide used as high efficient electrocatalyst in activated carbon air-cathode microbial fuel cell

NASA Astrophysics Data System (ADS)

Yang, Tingting; Wang, Zhong; Li, Kexun; Liu, Yi; Liu, Di; Wang, Junjie

2017-09-01

Herein, we report a simplistic method to fabricate the surface-oxidized cobalt phosphide (CoP) nanocrystals (NCs), which is used as electrocatalyst for oxygen reduction reaction (ORR) in microbial fuel cell (MFC) for the first time. The corallite-like CoP NCs are successfully prepared by a hydrothermal reaction following a phosphating treatment in N2 atmosphere. When used as an ORR catalyst, cobalt phosphide shows comparable onset potential, inferior resistance, as well as a small Tafel slope with long-term stability in neutral media. The maximum power density of MFC embellished with 10% CoP reached 1914.4 ± 59.7 mW m-2, which is 108.5% higher than the control. The four-electron pathway, observed by the RDE, plays a crucial role in electrochemical catalytic activity. In addition, material characterizations indicate that the surface oxide layer (CoOx) around the metallic CoP core is important and beneficial for ORR. Accordingly, it can be expected that the as-synthesized CoP will be a promising candidate of the non-precious metal ORR electrocatalysts for electrochemical energy applications.

Use of continuous renal replacement therapy in acute aluminum phosphide poisoning: a novel therapy.

PubMed

Nasa, Prashant; Gupta, Ankur; Mangal, Kishore; Nagrani, S K; Raina, Sanjay; Yadav, Rohit

2013-09-01

Aluminum phosphide is most common cause of poisoning in northern India. There is no specific antidote available and management of such cases is mainly supportive with high mortality. We present two cases of severe acute aluminium phosphide poisoning where continuous renal replacement therapy (CRRT) was started early along with other resuscitative measures and both the patients survived.

CoP Nanoparticles in Situ Grown in Three-Dimensional Hierarchical Nanoporous Carbons as Superior Electrocatalysts for Hydrogen Evolution.

PubMed

Yuan, Weiyong; Wang, Xiaoyan; Zhong, Xiaoling; Li, Chang Ming

2016-08-17

The development of efficient and low-cost hydrogen evolution reaction (HER) catalysts is critical for storing energy in hydrogen via water splitting but still presents great challenges. Herein, we report synthesis of three-dimensional (3-D) hierarchical nanoporous carbon (HNC) supported transition metal phosphides (TMPs) for the first time by in situ growth of CoP nanoparticles (NPs) in CaCO3 NP-templated Cinnamomum platyphyllum leaf extract-derived carbon. They were subsequently employed as a HER catalyst, showing an onset potential of 7 mV and an overpotential of 95.8 mV to achieve 10 mA cm(-2), a Tafel plot of 33 mV dec(-1), and an exchange current density of 0.1182 mA cm(-2), of which the onset overpotential and the Tafel plot are the lowest reported for non-noble-metal HER catalysts, and the overpotential to achieve 10 mA cm(-2) and the exchange current density also compare favorably to most reported HER catalysts. In addition, this catalyst exhibits excellent durability with negligible loss in current density after 2000 CV cycles ranging from +0.01 to -0.17 V vs RHE at a scan rate of 100 mV s(-1) or 22 h of chronoamperometric measurement at an overpotential of 96 mV and a high Faraday efficiency of close to 100%. This work not only creates a novel high-performance non-noble-metal HER electrocatalyst and demonstrates the great advantages of the in situ grown 3-D HNC supported TMP NPs for the electrocatalysis of HER but also offers scientific insight into the mechanism for the in situ growth of TMP and their precursor NPs, in which an ultralow reactant concentration and rich functional groups on the 3-D HNC support play critical roles.

Composition-Dependent Morphology of Bi- and Trimetallic Phosphides: Construction of Amorphous Pd-Cu-Ni-P Nanoparticles as a Selective and Versatile Catalyst.

PubMed

Zhao, Ming; Ji, Yuan; Wang, Mengyue; Zhong, Ning; Kang, Zinan; Asao, Naoki; Jiang, Wen-Jie; Chen, Qiang

2017-10-11

Amorphous materials have been widely researched in heterogeneous catalysis and for next-generation batteries. However, the well-defined production of high-quality (e.g., monodisperse and high surface area) amorphous alloy nanomaterials has rarely been reported. In this work, we investigated the correlations among the composition, morphology, and catalysis of various Pd-M-P nanoparticles (NPs) (M = Cu or Ni), which indicated that less Cu (≤20 atom %) was necessary for the formation of an amorphous morphology. The amorphous Pd-Cu-Ni-P NPs were fabricated with a controllable size and characterized carefully, which show excellent selective catalysis in the semihydrogenation of alkynes, hydrogenation of quinoline, and oxidation of primary alcohols. The uniqueness of the catalytic performance was confirmed by control experiments with monometallic Pd, amorphous Pd-Ni-P NPs, crystalline Pd-Cu-P NPs, and a crystalline counterpart of Pd-Cu-Ni-P catalyst. The catalytic selectivity likely arose from improved Pd-M (M = Cu or Ni) synergistic effects in the amorphous phase and the electron deficiency of Pd. The model reactions proceeded under H 2 or O 2 gas without any additives, bases, or metal oxide supports, and the catalyst could be reused several times. This report is expected to shed light on the design of amorphous alloy nanomaterials as green and inexpensive catalysts for atom-economic and selective reactions.

Enhanced activity of Pt/CNTs anode catalyst for direct methanol fuel cells using Ni2P as co-catalyst

NASA Astrophysics Data System (ADS)

Li, Xiang; Luo, Lanping; Peng, Feng; Wang, Hongjuan; Yu, Hao

2018-03-01

The direct methanol fuel cell is a promising energy conversion device because of the utilization of the state-of-the-art platinum (Pt) anode catalyst. In this work, novel Pt/Ni2P/CNTs catalysts were prepared by the H2 reduction method. It was found that the activity and stability of Pt for methanol oxidation reaction (MOR) could be significantly enhanced while using nickel phosphide (Ni2P) nanoparticles as co-catalyst. X-ray photoelectron spectroscopy revealed that the existence of Ni2P affected the particle size and electronic distribution of Pt obviously. Pt/CNTs catalyst, Pt/Ni2P/CNTs catalysts with different Ni2P amount were synthesized, among which Pt/6%Ni2P/CNTs catalyst exhibited the best MOR activity of 1400 mAmg-1Pt, which was almost 2.5 times of the commercial Pt/C-JM catalyst. Moreover, compared to other Pt-based catalysts, this novel Pt/Ni2P/CNTs catalyst also exhibited higher onset current density and better steady current density. The result of this work may provide positive guidance to the research on high efficiency and stability of Pt-based catalyst for direct methanol fuel cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendoza-Garcia, Adriana; Zhu, Huiyuan; Yu, Yongsheng

Presented here is a facile approach to bimetallic phosphides, Co-Fe-P, via high-temperature (300°C) reaction between Co-Fe-O nanoparticles and trioctylphosphine. The growth of Co-Fe-P from the Co-Fe-O is anisotropic. As a result, Co-Fe-P nanorods (from the polyhedral Co-Fe-O nanoparticles) and sea-urchin-like Co-Fe-P (from the cubic Co-Fe-O nanoparticles) are synthesized with both nanorod and the sea-urchin-arm dimensions controlled by Co/Fe ratios. The Co-Fe-P structure, especially the sea-urchin-like (Co 0.54Fe 0.46) 2P, shows enhanced catalysis for oxygen evolution reaction in KOH with its catalytic efficiency surpassing Ir catalyst. Our synthesis is simple and may be readily extended to the preparation of other multimetallicmore » phosphides for important catalysis and energy storage applications.« less

Comparison of GaP nanowires grown from Au and Sn vapor-liquid-solid catalysts as photoelectrode materials

NASA Astrophysics Data System (ADS)

Lee, Sudarat; Wen, Wen; Cheek, Quintin; Maldonado, Stephen

2018-01-01

Gallium phosphide (GaP) nanowire film electrodes have been prepared via solid sublimation of GaP powder using both gold (Au) and tin (Sn) nanoparticles as the vapor-liquid-solid (VLS) catalysts on Si(1 1 1) and GaP(1 1 1)B substrates. The resultant GaP nanowires are compared and contrasted in terms of structures and photoactivity in photoelectrochemical half cells. Raman spectra implicated a difference in the surface condition of the two types of nanowires. Complete wet etching removal of metallic VLS catalysts from the as-prepared GaP nanowires was possible with Sn catalysts but not with Au catalysts. The photoresponses of both Sn- and Au-seeded GaP nanowire films were collected and examined under 100 mW cm-2 white light illumination. Au-seeded nanowire films exhibited strong n-type characteristics when measured in nonaqueous electrolyte with ferrocene/ferricenium as the redox species while Sn-seeded nanowires showed behavior consistent with degenerate n-type doping.

Gallium phosphide nanowires as a substrate for cultured neurons.

PubMed

Hällström, Waldemar; Mårtensson, Thomas; Prinz, Christelle; Gustavsson, Per; Montelius, Lars; Samuelson, Lars; Kanje, Martin

2007-10-01

Dissociated sensory neurons were cultured on epitaxial gallium phosphide (GaP) nanowires grown vertically from a gallium phosphide surface. Substrates covered by 2.5 microm long, 50 nm wide nanowires supported cell adhesion and axonal outgrowth. Cell survival was better on nanowire substrates than on planar control substrates. The cells interacted closely with the nanostructures, and cells penetrated by hundreds of wires were observed as well as wire bending due to forces exerted by the cells.

Directed surfaces structures and interfaces for enhanced electrocatalyst activity, selectivity, and stability for energy conversion reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaramillo, Thomas F.

In this project, we have employed a systematic approach to develop active, selective, and stable catalyst materials for important electrochemical reactions involving energy conversion. In particular, we have focused our attention on developing active catalyst materials for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). HER: We have synthesized and investigated several highly active and acid stable non-precious metal HER catalysts, including: [Mo 3S 13] 2- nanoclusters (Nature Chemistry, 2014) and molybdenum phosphosulfide (MoP|S) (Angewandte Chemie, 2014). We have also aimed to engineer these catalyst formulations in a membrane electrode assembly (MEA) for fundamentalmore » studies of water electrolysis at high current densities, approximately 1 A/cm 2 (ChemSusChem, 2015). We furthermore investigated transition metal phosphide (TMP) catalysts for HER by a combined experimental–theoretical approach (Energy & Environmental Science, 2015). By synthesizing different TMPs and comparing experimentally determined HER activities with the hydrogen adsorption free energies, ΔG H, calculated by density functional theory, we showed that the TMPs follow a volcano relationship for the HER. Using our combined experimental–theoretical model, we predicted that the mixed metal TMP, Fe 0.5Co 0.5P, should have a near-optimal ΔG H. We synthesized several mixtures of Co and Fe phosphides alloys and confirmed that Fe 0.5Co 0.5P exhibits the highest HER activity of the investigated TMPs (Energy & Environmental Science, 2015). The understanding gained as to how to improve catalytic activity for the HER, particularly for non-precious metal materials, is important to DOE targets for sustainable H 2 production. OER: We have developed a SrIrO 3/IrO x catalyst for acidic conditions (submitted, 2016). The SrIrO 3/IrO x catalyst significantly outperforms rutile IrO 2 and RuO 2, the only other OER catalysts to have reasonable stability and activity in acidic electrolyte, and in fact demonstrates the best activity for any known OER catalyst measured in either acidic or in alkaline electrolyte. For alkaline conditions we have demonstrated that the combined effect of cerium as a dopant and gold as a metal support, significantly enhances the OER activity of electrodeposited NiO x films. This NiCeO x-Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts reported to date (Nature Energy, accepted 2016). These studies of new catalysts for the OER, both in acid and in base, are fundamental to enabling new technologies of interest for the DOE, including the production of sustainable fuels and chemicals. ORR: One method to significantly reduce the Pt loading in fuel cell devices is to increase the ORR activity of Pt based systems. To this end we have synthesized a high surface area supported meso-structured Pt xNi alloy thin film with a double gyroid morphology that both exhibits high activity and stability for the ORR (submitted, 2016). We have furthermore developed a Ru-core, Pt-shell system that improves the per Pt site activity by more than a factor of 2 (ChemElectroChem, 2014). Further refinement, optimizing Pt-shell thickness and reducing particle sintering during processing, enabled us to obtain a mass activity that is 2 times higher than commercial Pt/C from TKK. These are important contributions to the DOE goal of reducing Pt loading since an improved understanding of how to increase mass activity and stability helps enable low Pt content fuel cells.« less

Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Britto, Reuben J.; Benck, Jesse D.; Young, James L.

2016-06-02

Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis since MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, andmore » light limited current density) after 60 hours of operation. This represents a five-hundred fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions.« less

Two-Dimensional Phosphorene-Derived Protective Layers on a Lithium Metal Anode for Lithium-Oxygen Batteries.

PubMed

Kim, Youngjin; Koo, Dongho; Ha, Seongmin; Jung, Sung Chul; Yim, Taeeun; Kim, Hanseul; Oh, Seung Kyo; Kim, Dong-Min; Choi, Aram; Kang, Yongku; Ryu, Kyoung Han; Jang, Minchul; Han, Young-Kyu; Oh, Seung M; Lee, Kyu Tae

2018-05-04

Lithium-oxygen (Li-O 2 ) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decomposition and Li dendrite growth. This suppression is attributed to thermodynamic properties of the electrochemically active lithium phosphide protective layer. The electrolyte decomposition is suppressed on the protective layer because the redox potential of lithium phosphide layer is higher than that of electrolyte decomposition. Li plating is thermodynamically unfavorable on lithium phosphide layers, which hinders Li dendrite growth during cycling. As a result, the nanosized lithium phosphide protective layer improves the cycle performance of Li symmetric cells and Li-O 2 batteries with various electrolytes including lithium bis(trifluoromethanesulfonyl)imide in N,N-dimethylacetamide. A variety of ex situ analyses and theoretical calculations support these behaviors of the phosphorene-derived lithium phosphide protective layer.

Aqueous corrosion of phosphide minerals from iron meteorites: a highly reactive source of prebiotic phosphorus on the surface of the early Earth.

PubMed

Pasek, Matthew A; Lauretta, Dante S

2005-08-01

We present the results of an experimental study of aqueous corrosion of Fe-phosphide under conditions relevant to the early Earth. The results strongly suggest that iron meteorites were an important source of reactive phosphorus (P), a requirement for the formation of P-based life. We further demonstrate that iron meteorites were an abundant source of phosphide minerals early in Earth history. Phosphide corrosion was studied in five different solutions: deionized water, deionized water buffered with sodium bicarbonate, deionized water with dissolved magnesium and calcium chlorides, deionized water containing ethanol and acetic acid, and deionized water containing the chlorides, ethanol, and acetic acid. Experiments were performed in the presence of both air and pure Ar gas to evaluate the effect of atmospheric chemistry. Phosphide corrosion in deionized water results in a metastable mixture of mixed-valence, P-bearing ions including pyrophosphate and triphosphate, key components for metabolism in modern life. In a pH-buffered solution of NaHCO(3), the condensed and reduced species diphosphonate is an abundant corrosion product. Corrosion in ethanol- and acetic acid-containing solutions yields additional P-bearing organic molecules, including acetyl phosphonate and a cyclic triphosphorus molecule. Phosphonate is a major corrosion product of all experiments and is the only P-bearing molecule that persists in solutions with high concentrations of magnesium and calcium chlorides, which suggests that phosphonate may have been a primitive oceanic source of P. The stability and reactivity of phosphonate and hypophosphite in solution were investigated to elucidate reaction mechanisms and the role of mineral catalysts on P-solution chemistry. Phosphonate oxidation is rapid in the presence of Fe metal but negligible in the presence of magnetite and in the control sample. The rate of hypophosphite oxidation is independent of reaction substrate.

Sugar Blowing-Induced Porous Cobalt Phosphide/Nitrogen-Doped Carbon Nanostructures with Enhanced Electrochemical Oxidation Performance toward Water and Other Small Molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Chengzhou; Fu, Shaofang; Xu, Bo Z.

Finely controlled synthesis of high active and robust nonprecious metal catalysts with excellent catalytic efficiency in oxygen evolution reaction (OER) is extremely vital for making the water splitting process more energy-efficient and economical. Among these noble metal-free catalysts, transition-metal-based nanomaterials are considered as one of the most promising OER catalysts due to their relatively low-cost intrinsic activities, high abundance and diversity in terms of structure and morphology. In this work, we reported a facile sugar-blowing technique and low-temperature phosphorization to generate 3D self-supported metal involved carbon nanostructures, which termed as Co2P@Co/nitrogen-doped carbon (Co2P@Co/N-C). By capitalizing on the 3D porous nanostructuresmore » with high surface area, generously dispersed active sites, the intimate interaction between active sites and 3D N-doped carbon, the resultant Co2P@Co/N-C exhibited satisfying OER performance superior to CoO@Co/N-C, delivering 10 mA cm-2 at overpotential of 0.32 V. It is noting that in contrast to the substantial current density loss of RuO2, Co2P@Co/N-C showed much enhanced catalytic activity during the stability test and the 1.8-fold increase in current density was observed after stability test. Furthermore, the obtained Co2P@Co/N-C can also be served as an excellent nonprecious metal catalyst for methanol and glucose electrooxidation in alkaline media, further extending their potential applications.« less

Scaling Relations for Adsorption Energies on Doped Molybdenum Phosphide Surfaces

DOE PAGES

Fields, Meredith; Tsai, Charlie; Chen, Leanne D.; ...

2017-03-10

Molybdenum phosphide (MoP), a well-documented catalyst for applications ranging from hydrotreating reactions to electrochemical hydrogen evolution, has yet to be mapped from a more fundamental perspective, particularly in the context of transition-metal scaling relations. In this work, we use periodic density functional theory to extend linear scaling arguments to doped MoP surfaces and understand the behavior of the phosphorus active site. The derived linear relationships for hydrogenated C, N, and O species on a variety of doped surfaces suggest that phosphorus experiences a shift in preferred bond order depending on the degree of hydrogen substitution on the adsorbate molecule. Thismore » shift in phosphorus hybridization, dependent on the bond order of the adsorbate to the surface, can result in selective bond weakening or strengthening of chemically similar species. As a result, we discuss how this behavior deviates from transition-metal, sulfide, carbide, and nitride scaling relations, and we discuss potential applications in the context of electrochemical reduction reactions.« less

Colloidal Cobalt Phosphide Nanocrystals as Trifunctional Electrocatalysts for Overall Water Splitting Powered by a Zinc–Air Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hui; Li, Qi; Wen, Peng

Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this paper, highly monodisperse CoP and Co 2P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co 2P NCs show higher OER performance owing to easier formation of plentiful Co 2P@COOH heterojunctions. Density functional theory calculation results indicate that themore » desorption of OH* from cobalt sites is the rate-limiting step for both CoP and Co 2P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co 2P NC anode can achieve a current density of 10 mA cm -2 at 1.56 V, comparable even to the noble metal-based Pt/C and RuO 2/C pair. Finally and furthermore, the CoP NCs are employed as an air cathode in a primary zinc–air battery, exhibiting a high power density of 62 mW cm -2 and good stability.« less

Colloidal Cobalt Phosphide Nanocrystals as Trifunctional Electrocatalysts for Overall Water Splitting Powered by a Zinc–Air Battery

DOE PAGES

Li, Hui; Li, Qi; Wen, Peng; ...

2018-01-15

Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this paper, highly monodisperse CoP and Co 2P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co 2P NCs show higher OER performance owing to easier formation of plentiful Co 2P@COOH heterojunctions. Density functional theory calculation results indicate that themore » desorption of OH* from cobalt sites is the rate-limiting step for both CoP and Co 2P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co 2P NC anode can achieve a current density of 10 mA cm -2 at 1.56 V, comparable even to the noble metal-based Pt/C and RuO 2/C pair. Finally and furthermore, the CoP NCs are employed as an air cathode in a primary zinc–air battery, exhibiting a high power density of 62 mW cm -2 and good stability.« less

Essential elucidation for preparation of supported nickel phosphide upon nickel phosphate precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xuguang, E-mail: liuxuguang@qust.edu.cn; Xu, Lei; Zhang, Baoquan

2014-04-01

Preparation of supported nickel phosphide (Ni{sub 2}P) depends on nickel phosphate precursor, generally related to its chemical composition and supports. Study of this dependence is essential and meaningful for the preparation of supported Ni{sub 2}P with excellent catalytic activity. The chemical nature of nickel phosphate precursor is revealed by Raman and UV–vis spectra. It is found that initial P/Ni mole ratio ≥0.8 prohibits the Ni-O-Ni bridge bonding (i.e., nickel oxide). This chemical bonding will not result in Ni{sub 2}P structure, verified by XRD characterization results. The alumina (namely, γ-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, or α-Al{sub 2}O{sub 3}) with distinctmore » physiochemical properties also results in diverse chemical nature of nickel phosphate, and then different nickel phosphides. The influence of alumina support on producing Ni{sub 2}P was explained by the theory of surface energy heterogeneity, calculated by the NLDFT method based on N{sub 2}-sorption isotherm. The uniform surface energy of α-Al{sub 2}O{sub 3} results only in the nickel phosphosate precursor and thus the Ni{sub 2}P phase. - Graphical abstract: Surface energy heterogeneity in alumina (namely α-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, and γ-Al{sub 2}O{sub 3}) supported multi-oxidic precursors with different reducibilities and thus diverse nickel phosphides (i.e., Ni{sub 3}P, Ni{sub 12}P{sub 5}, Ni{sub 2}P). - Highlights: • Preparing pure Ni{sub 2}P. • Elucidating nickel phosphate precursor. • Associating with surface energy.« less

Preparation and characterization of a supported system of Ni2P/Ni12P5 nanoparticles and their use as the active phase in chemoselective hydrogenation of acetophenone

NASA Astrophysics Data System (ADS)

Costa, Dolly C.; Soldati, Analía L.; Pecchi, Gina; Bengoa, José Fernando; Marchetti, Sergio Gustavo; Vetere, Virginia

2018-05-01

Ni2P/Ni12P5 nanoparticles were obtained by thermal decomposition of nickel organometallic salt at low temperature. The use of different characterization techniques allowed us to determine that this process produced a mixture of two nickel phosphide phases: Ni2P and Ni12P5. These nickel phosphides nanoparticles, supported on mesoporous silica, showed activity and high selectivity for producing the hydrogenation of the acetophenone carbonyl group to obtain 1-phenylethanol. This is a first report that demonstrates the ability of supported Ni2P/Ni12P5 nanoparticles to produce the chemoselective hydrogenation of acetophenone. We attribute these special catalytic properties to the particular geometry of the Ni–P sites on the surface of the nanoparticles. This is an interesting result because the nickel phosphides have a wide composition range (from Ni3P to NiP3), with different crystallographic structures, therefore we think that different phases could be active and selective to hydrogenate many important molecules with more than one functional group.

Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen.

PubMed

Liu, Mengjia; Li, Jinghong

2016-01-27

The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal-organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec(-1), and a current density of 10 mA cm(-2) at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations.

InP Nanoflag Growth from a Nanowire Template by in Situ Catalyst Manipulation.

PubMed

Kelrich, Alexander; Sorias, Ofir; Calahorra, Yonatan; Kauffmann, Yaron; Gladstone, Ran; Cohen, Shimon; Orenstein, Meir; Ritter, Dan

2016-04-13

Quasi-two-dimensional semiconductor materials are desirable for electronic, photonic, and energy conversion applications as well as fundamental science. We report on the synthesis of indium phosphide flag-like nanostructures by epitaxial growth on a nanowire template at 95% yield. The technique is based on in situ catalyst unpinning from the top of the nanowire and its induced migration along the nanowire sidewall. Investigation of the mechanism responsible for catalyst movement shows that its final position is determined by the structural defect density along the nanowire. The crystal structure of the "flagpole" nanowire is epitaxially transferred to the nanoflag. Pure wurtzite InP nanomembranes with just a single stacking fault originating from the defect in the flagpole that pinned the catalyst were obtained. Optical characterization shows efficient highly polarized photoluminescence at room temperature from a single nanoflag with up to 90% degree of linear polarization. Electric field intensity enhancement of the incident light was calculated to be 57, concentrated at the nanoflag tip. The presented growth method is general and thus can be employed for achieving similar nanostructures in other III-V semiconductor material systems with potential applications in active nanophotonics.

High-Performance Rh 2 P Electrocatalyst for Efficient Water Splitting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Haohong; Li, Dongguo; Tang, Yan

2017-04-05

The search for active, stable, and cost-efficient electrocatalysts for hydrogen production via water splitting could make a substantial impact on energy technologies that do not rely on fossil fuels. Here we report the synthesis of rhodium phosphide electrocatalyst with low metal loading in the form of nanocubes (NCs) dispersed in high-surface-area carbon (Rh2P/C) by a facile solvo-thermal approach. The Rh2P/C NCs exhibit remarkable performance for hydrogen evolution reaction and oxygen evolution reaction compared to Rh/C and Pt/C catalysts. The atomic structure of the Rh2P NCs was directly observed by annular dark-field scanning transmission electron microscopy, which revealed a phosphorus-rich outermostmore » atomic layer. Combined experimental and computational studies suggest that surface phosphorus plays a crucial role in determining the robust catalyst properties.« less

Confined Molybdenum Phosphide in P-Doped Porous Carbon as Efficient Electrocatalysts for Hydrogen Evolution.

PubMed

Li, Ji-Sen; Zhang, Shuai; Sha, Jing-Quan; Wang, Hao; Liu, Ming-Zhu; Kong, Ling-Xin; Liu, Guo-Dong

2018-05-09

Highly efficient electrocatalysts for hydrogen evolution reactions (HER) are crucial for electrochemical water splitting, where high-cost and low-abundance Pt-based materials are the benchmark catalysts for HER. Herein, we report the fabrication of MoP nanoparticles confined in P-doped porous carbon (MoP@PC) via a metal-organic framework-assisted route for the first time. Remarkably, due to the synergistic effects of MoP nanocrystals, P dopant, and porous carbon, the resulting MoP@PC composite exhibits superior HER catalytic activity with an onset overpotential of 97 mV, a Tafel slope of 59.3 mV dec -1 , and good long-term durability, which compares to those of most reported MoP-based HER catalysts. Most importantly, the work opens a new route in the development of high-performance nonprecious HER electrocatalysts derived from MOFs.

Phosphorization boosts the capacitance of mixed metal nanosheet arrays for high performance supercapacitor electrodes.

PubMed

Lan, Yingying; Zhao, Hongyang; Zong, Yan; Li, Xinghua; Sun, Yong; Feng, Juan; Wang, Yan; Zheng, Xinliang; Du, Yaping

2018-05-01

Binary transition metal phosphides hold immense potential as innovative electrode materials for constructing high-performance energy storage devices. Herein, porous binary nickel-cobalt phosphide (NiCoP) nanosheet arrays anchored on nickel foam (NF) were rationally designed as self-supported binder-free electrodes with high supercapacitance performance. Taking the combined advantages of compositional features and array architectures, the nickel foam supported NiCoP nanosheet array (NiCoP@NF) electrode possesses superior electrochemical performance in comparison with Ni-Co LDH@NF and NiCoO2@NF electrodes. The NiCoP@NF electrode shows an ultrahigh specific capacitance of 2143 F g-1 at 1 A g-1 and retained 1615 F g-1 even at 20 A g-1, showing excellent rate performance. Furthermore, a binder-free all-solid-state asymmetric supercapacitor device is designed, which exhibits a high energy density of 27 W h kg-1 at a power density of 647 W kg-1. The hierarchical binary nickel-cobalt phosphide nanosheet arrays hold great promise as advanced electrode materials for supercapacitors with high electrochemical performance.

Patents and Licenses Through 1994,

DTIC Science & Technology

1994-01-01

Chiang was employed at Honeywell Radiation Center, where she worked on mercury cadmium telluride (HgCdTe) and gallium phosphide photoconductive...5,251,225 Gallium Indium Arsenide Phosphide 4,258,375; 4,372,791; 4,718,070;4,722,092 Gallium Indium Arsenide Phosphide /Indium Phosphide ...Indirect-Gap Semiconductor 3,636,471 Indium Arsenide 2,990,259 Indium Gallium Arsenide 4,746,620 Indium Phosphide 2,990,259; 4,376,285

Fundamental studies of the metallurgical, electrical, and optical properties of gallium phosphide and gallium phosphide alloys

NASA Technical Reports Server (NTRS)

1972-01-01

Abstracts, bibliographic data, oral presentations, and published papers on (1) Diffusion of Sulfur in Gallium Phosphide and Gallium Arsenide, and (2) Properties of Gallium Phosphide Schottky Barrier Rectifiers for Use at High Temperature are presented.

Boron Arsenide and Boron Phosphide for High Temperature and Luminescent Devices. [semiconductor devices - crystal growth/crystal structure

NASA Technical Reports Server (NTRS)

Chu, T. L.

1975-01-01

The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk crystals of boron arsenide were prepared by the chemical transport technique, and their carrier concentration and Hall mobility were measured. The growth of boron arsenide crystals from high temperature solutions was attempted without success. Bulk crystals of boron phosphide were also prepared by chemical transport and solution growth techniques. Techniques required for the fabrication of boron phosphide devices such as junction shaping, diffusion, and contact formation were investigated. Alloying techniques were developed for the formation of low-resistance ohmic contacts to boron phosphide. Four types of boron phosphide devices were fabricated: (1) metal-insulator-boron phosphide structures, (2) Schottky barriers; (3) boron phosphide-silicon carbide heterojunctions; and (4) p-n homojunctions. Easily visible red electroluminescence was observed from both epitaxial and solution grown p-n junctions.

Metal Doping Effect of the M-Co2P/Nitrogen-Doped Carbon Nanotubes (M = Fe, Ni, Cu) Hydrogen Evolution Hybrid Catalysts.

PubMed

Pan, Yuan; Liu, Yunqi; Lin, Yan; Liu, Chenguang

2016-06-08

The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M-Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M-Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M-Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe-Co2P/NCNTs > Ni-Co2P/NCNTs > Cu-Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the [111] crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Fe(δ+) has the highest positive charge among all the M-Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe-Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER.

Method for production of free-standing polycrystalline boron phosphide film

DOEpatents

Baughman, Richard J.; Ginley, David S.

1985-01-01

A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

40 CFR 180.284 - Zinc phosphide; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Zinc phosphide; tolerances for... § 180.284 Zinc phosphide; tolerances for residues. (a) General. Tolerances are established for residues of the phosphine resulting from the use of the rodenticide zinc phosphide in or on the raw...

Photovoltaic cells employing zinc phosphide

DOEpatents

Barnett, Allen M.; Catalano, Anthony W.; Dalal, Vikram L.; Masi, James V.; Meakin, John D.; Hall, Robert B.

1984-01-01

A photovoltaic cell having a zinc phosphide absorber. The zinc phosphide can be a single or multiple crystal slice or a thin polycrystalline film. The cell can be a Schottky barrier, heterojunction or homojunction device. Methods for synthesizing and crystallizing zinc phosphide are disclosed as well as a method for forming thin films.

Free-standing polycrystalline boron phosphide film and method for production thereof

DOEpatents

Baughman, R.J.; Ginley, D.S.

1982-09-09

A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

Pesticide poisoning.

PubMed

Goel, Ashish; Aggarwal, Praveen

2007-01-01

Acute poisoning with pesticides is a global public health problem and accounts for as many as 300,000 deaths worldwide every year. The majority of deaths occur due to exposure to organophosphates, organochlorines and aluminium phosphide. Organophosphate compounds inhibit acetylcholinesterase resulting in acute toxicity. Intermediate syndrome can develop in a number of patients and may lead to respiratory paralysis and death. Management consists of proper oxygenation, atropine in escalating doses and pralidoxime in high doses. It is Important to decontaminate the skin while taking precautions to avoid secondary contamination of health personnel. Organochlorine pesticides are toxic to the central nervous system and sensitize the myocardium to catecholamines. Treatment involves supportive care and avoiding exogenous sympathomimetic agents. Ingestion of paraquat causes severe inflammation of the throat, corrosive injury to the gastrointestinal tract, renal tubular necrosis, hepatic necrosis and pulmonary fibrosis. Administration of oxygen should be avoided as it produces more fibrosis. Use of immunosuppressive agents have improved outcome in patients with paraquat poisoning. Rodenticides include thallium, superwarfarins, barium carbonate and phosphides (aluminium and zinc phosphide). Alopecia is an atypical feature of thallium toxicity. Most exposures to superwarfarins are harmless but prolonged bleeding may occur. Barium carbonate Ingestion can cause severe hypokalaemia and respiratory muscle paralysis. Aluminium phosphide is a highly toxic agent with mortality ranging from 37% to 100%. It inhibits mitochondrial cytochrome c oxidase and leads to pulmonary and cardiac toxicity. Treatment is supportive with some studies suggesting a beneficial effect of magnesium sulphate. Pyrethroids and insect repellants (e.g. diethyltoluamide) are relatively harmless but can cause toxic effects to pulmonary and central nervous systems. Ethylene dibromide-a highly toxic, fumigant pesticide-produces oral ulcerations, followed by liver and renal toxicity, and is almost uniformly fatal. Physicians working in remote and rural areas need to be educated about early diagnosis and proper management using supportive care and antidotes, wherever available.

Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides.

PubMed

Guo, Lijuan; Zhao, Yu; Yao, Zhiwei

2016-01-21

This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.

Efficient telecom to visible wavelength conversion in doubly resonant gallium phosphide microdisks

NASA Astrophysics Data System (ADS)

Lake, David P.; Mitchell, Matthew; Jayakumar, Harishankar; dos Santos, Laís Fujii; Curic, Davor; Barclay, Paul E.

2016-01-01

Resonant second harmonic generation between 1550 nm and 775 nm with normalized outside efficiency > 3.8 × 10 - 4 mW - 1 is demonstrated in a gallium phosphide microdisk supporting high-Q modes at visible ( Q ˜ 10 4 ) and infrared ( Q ˜ 10 5 ) wavelengths. The double resonance condition is satisfied for a specific pump power through intracavity photothermal temperature tuning using ˜ 360 μ W of 1550 nm light input to a fiber taper and coupled to a microdisk resonance. Power dependent efficiency consistent with a simple model for thermal tuning of the double resonance condition is observed.

InP (Indium Phosphide): Into the future

NASA Technical Reports Server (NTRS)

Brandhorst, Henry W., Jr.

1989-01-01

Major industry is beginning to be devoted to indium phosphide and its potential applications. Key to these applications are high speed and radiation tolerance; however the high cost of indium phosphide may be an inhibitor to progress. The broad applicability of indium phosphide to many devices will be discussed with an emphasis on photovoltaics. Major attention is devoted to radiation tolerance and means of reducing cost of devices. Some of the approaches applicable to solar cells may also be relevant to other devices. The intent is to display the impact of visionary leadership in the field and enable the directions and broad applicability of indium phosphide.

The relation of the yield stress of high-pressure anvils to the pressure attained at yielding and the ultimate attainable pressure

NASA Technical Reports Server (NTRS)

Panda, P. C.; Ruoff, A. L.

1979-01-01

A sensitive microprofilometer was used to determine the onset of yielding in the anvils of a supported opposed anvil device for the case of 3% cobalt-cemented tungsten carbide as the anvil material. In addition, it is shown how the commencement of yielding in boron carbide pistons, the yield strength being known, can be used to obtain the transition pressure to a conducting phase in gallium phosphide. The transition pressures of bismuth and gallium phosphide are obtained and it is found that these transitions are extremely close to the maximum attainable pressure in, respectively, a maraging steel and a 3% cobalt-cemented tungsten carbide.

Heterodoped nanotubes: theory, synthesis, and characterization of phosphorus-nitrogen doped multiwalled carbon nanotubes.

PubMed

Cruz-Silva, Eduardo; Cullen, David A; Gu, Lin; Romo-Herrera, Jose Manuel; Muñoz-Sandoval, Emilio; López-Urías, Florentino; Sumpter, Bobby G; Meunier, Vincent; Charlier, Jean-Christophe; Smith, David J; Terrones, Humberto; Terrones, Mauricio

2008-03-01

Arrays of multiwalled carbon nanotubes doped with phosphorus (P) and nitrogen (N) are synthesized using a solution of ferrocene, triphenyl-phosphine, and benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe(3)P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples were examined by high resolution electron microscopy and microanalysis techniques, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The PN-doped structures reveal important morphology and chemical changes when compared to N-doped nanotubes. These types of heterodoped nanotubes are predicted to offer many new opportunities in the fabrication of fast-response chemical sensors.

Aluminum Phosphide Poisoning-Related Deaths in Tehran, Iran, 2006 to 2013

PubMed Central

Etemadi-Aleagha, Afshar; Akhgari, Maryam; Iravani, Fariba Sardari

2015-01-01

Abstract Metal phosphides such as aluminum phosphide are potent insecticides. This highly toxic substance is used for rice and other grains protection in Iran. Due to its high toxicity potential and easy availability, it is widely used as a suicide poison. This substance has no effective antidote and the incidence of deaths due to its poisoning is increasing day by day in Iran. The present study was conducted to show the increasing incidence of fatal aluminum phosphide poisoning and its toxicological and forensic aspects in an 8-year study, 2006 to 2013. Autopsy sheets were reviewed and cases with the history of aluminum phosphide poisoning were selected. Toxicological analysis results, demographic and necroscopic examination findings were studied. A total of 51.8% of studied cases were female. Most of the cases were between 10 and 40 years old. The manner of death was self-poisoning in 85% of cases. Morphine, ethanol, and amitriptyline were the most common additional drugs detected in toxicological analysis. The incidence of fatal aluminum phosphide poisoning cases referred for phosphine analysis was 5.22 and 37.02 per million of population of Tehran in 2006 and 2013, respectively. The results of this study showed that in spite of ban and restrictions, there was a dramatic increase in the incidence of fatal aluminum phosphide poisoning in Tehran from 2006 to 2013. Safety alert should be highlighted in training program for all population groups about the toxic effects of aluminum phosphide tablets. PMID:26402837

40 CFR 180.284 - Zinc phosphide; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Zinc phosphide; tolerances for residues. 180.284 Section 180.284 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.284 Zinc phosphide; tolerances for...

40 CFR 180.284 - Zinc phosphide; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Zinc phosphide; tolerances for residues. 180.284 Section 180.284 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.284 Zinc phosphide; tolerances for...

40 CFR 180.284 - Zinc phosphide; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Zinc phosphide; tolerances for residues. 180.284 Section 180.284 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.284 Zinc phosphide; tolerances for...

Metal Phosphides and Phosphates-based Electrodes for Electrochemical Supercapacitors.

PubMed

Li, Xin; Elshahawy, Abdelnaby M; Guan, Cao; Wang, John

2017-10-01

Phosphorus compounds, such as metal phosphides and phosphates have shown excellent performances and great potential in electrochemical energy storage, which are demonstrated by research works published in recent years. Some of these metal phosphides and phosphates and their hybrids compare favorably with transition metal oxides/hydroxides, which have been studied extensively as a class of electrode materials for supercapacitor applications, where they have limitations in terms of electrical and ion conductivity and device stability. To be specific, metal phosphides have both metalloid characteristics and good electric conductivity. For metal phosphates, the open-framework structures with large channels and cavities endow them with good ion conductivity and charge storage capacity. In this review, we present the recent progress on metal phosphides and phosphates, by focusing on their advantages/disadvantages and potential applications as a new class of electrode materials in supercapacitors. The synthesis methods to prepare these metal phosphides/phosphates are looked into, together with the scientific insights involved, as they strongly affect the electrochemical energy storage performance. Particular attentions are paid to those hybrid-type materials, where strong synergistic effects exist. In the summary, the future perspectives and challenges for the metal phosphides, phosphates and hybrid-types are proposed and discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave-assisted synthesis of transition metal phosphide

DOEpatents

Viswanathan, Tito

2014-12-30

A method of synthesizing transition metal phosphide. In one embodiment, the method has the steps of preparing a transition metal lignosulfonate, mixing the transition metal lignosulfonate with phosphoric acid to form a mixture, and subjecting the mixture to a microwave radiation for a duration of time effective to obtain a transition metal phosphide.

Porous Cobalt Phosphide Polyhedrons with Iron Doping as an Efficient Bifunctional Electrocatalyst.

PubMed

Li, Feng; Bu, Yunfei; Lv, Zijian; Mahmood, Javeed; Han, Gao-Feng; Ahmad, Ishfaq; Kim, Guntae; Zhong, Qin; Baek, Jong-Beom

2017-10-01

Iron (Fe)-doped porous cobalt phosphide polyhedrons are designed and synthesized as an efficient bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The synthesis strategy involves one-step route for doping foreign metallic element and forming porous cobalt phosphide polyhedrons. With varying doping levels of Fe, the optimized Fe-doped porous cobalt phosphide polyhedron exhibits significantly enhanced HER and OER performances, including low onset overpotentials, large current densities, as well as small Tafel slopes and good electrochemical stability during HER and OER. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Future Directions for Selected Topics in Physics and Materials Science

DTIC Science & Technology

2012-07-12

referred to as lightides (e.g. borides , nitrides, phosphides) • Materials for energy conversion, energy storage, energy transport and energy production...Distributed nanosystems and sensors • Strategy for multilayered combinatorics • lightides ( borides , nitrides, phosphides, • New applications for...Strategy for multilayered combinatorics Lightides ( borides , nitrides, phosphides) • Energy conversion, .storage and production • Precision control

Deoxygenation of Palmitic Acid on Unsupported Transition-Metal Phosphides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peroni, Marco; Lee, Insu; Huang, Xiaoyang

Abstract Highly active bulk transition metal phosphides (WP, MoP, and Ni2P) were synthesized for the catalytic hydrodeoxygenation of palmitic acid, hexadecanol, hexadecanal, and microalgae oil. The specific activities positively correlated with the concentration of exposed metal sites, although the relative rates changed with temperature due to activation energies varying from 57 kJ·mol-1 for MoP to 142 kJ·mol-1 for WP. The reduction of the fatty acid to the aldehyde occurs through a Langmuir-Hinshelwood mechanism, where the rate-determining step is the addition of the second H to the hydrocarbon. On WP, the conversion of palmitic acid proceeds via R-CH2COOH R-CH2CHO R-CH2CH2OH R-CHCH2more » R-CH2CH3 (hydrodeoxygenation). Decarbonylation of the intermittently formed aldehyde (R-CH2COOH R-CH2CHO R-CH3) was an important pathway on MoP and Ni2P. Conversion via dehydration to a ketene, followed by its decarbonylation occurred only on Ni2P. The rates of alcohol dehydration (R-CH2CH2OH R-CHCH2) correlate with the concentration of Lewis acid sites of the phosphides. Acknowledgements The authors would like to thank Roel Prins for the critical discussion of the results. We are also grateful to Xaver Hecht for technical support. Funding by the German Federal Ministry of Food and Agriculture in the framework of the Advanced Biomass Value project (03SF0446A) is gratefully acknowledged. J.A.L. acknowledges support for his contribution by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences for exploring non-oxidic supports for deoxygenation reactions.« less

Optimal design study of high efficiency indium phosphide space solar cells

NASA Technical Reports Server (NTRS)

Jain, Raj K.; Flood, Dennis J.

1990-01-01

Recently indium phosphide solar cells have achieved beginning of life AMO efficiencies in excess of 19 pct. at 25 C. The high efficiency prospects along with superb radiation tolerance make indium phosphide a leading material for space power requirements. To achieve cost effectiveness, practical cell efficiencies have to be raised to near theoretical limits and thin film indium phosphide cells need to be developed. The optimal design study is described of high efficiency indium phosphide solar cells for space power applications using the PC-1D computer program. It is shown that cells with efficiencies over 22 pct. AMO at 25 C could be fabricated by achieving proper material and process parameters. It is observed that further improvements in cell material and process parameters could lead to experimental cell efficiencies near theoretical limits. The effect of various emitter and base parameters on cell performance was studied.

Indium phosphide space solar cell research: Where we are and where we are going

NASA Technical Reports Server (NTRS)

Jain, R. K.; Flood, D. J.; Weinberg, Irving

1995-01-01

Indium phosphide is considered to be a strong contender for many photovoltaic space applications because of its radiation resistance and its potential for high efficiency. An overview of recent progress is presented, and possible future research directions for indium phosphide space solar cells are discussed. The topics considered include radiation damage studies and space flight experiments.

Electron emitting device and method of making the same

DOEpatents

Olsen, Gregory Hammond; Martinelli, Ramon Ubaldo; Ettenberg, Michael

1977-04-19

A substrate of single crystalline gallium arsenide has on a surface thereof a layer of single crystalline indium gallium phosphide. A layer of single crystalline gallium arsenide is on the indium gallium phosphide layer and a work function reducing material is on the gallium arsenide layer. The substrate has an opening therethrough exposing a portion of the indium gallium phosphide layer.

Porous Structured Ni–Fe–P Nanocubes Derived from a Prussian Blue Analogue as an Electrocatalyst for Efficient Overall Water Splitting

DOE PAGES

Xuan, Cuijuan; Wang, Jie; Xia, Weiwei; ...

2017-07-18

Exploring nonprecious metal electrocatalysts to replace the noble metal-based catalysts for full water electrocatalysis is still an ongoing challenge. In this work, porous structured ternary nickel–iron–phosphide (Ni–Fe–P) nanocubes were synthesized through one-step phosphidation of a Ni–Fe-based Prussian blue analogue. The Ni–Fe–P nanocubes exhibit a rough and loose porous structure on their surface under suitable phosphating temperature, which is favorable for the mass transfer and oxygen diffusion during the electrocatalysis process. As a result, Ni–Fe–P obtained at 350 °C with poorer crystallinity offers more unsaturated atoms as active sites to expedite the absorption of reactants. Additionally, the introduction of nickel improvedmore » the electronic structure and then reduced the charge-transfer resistance, which would result in a faster electron transport and an enhancement of the intrinsic electrocatalytic activities. Benefiting from the unique porous nanocubes and the chemical composition, the Ni–Fe–P nanocubes exhibit excellent hydrogen evolution reaction and oxygen evolution reaction activities in alkaline medium, with low overpotentials of 182 and 271 mV for delivering a current density of 10 mA cm–2, respectively. Moreover, the Ni–Fe–P nanocubes show outstanding stability for sustained water splitting in the two-electrode alkaline electrolyzer. Furthermore, this work not only provides a facile approach for designing bifunctional electrocatalysts but also further extends the application of metal–organic frameworks in overall water splitting.« less

Porous Structured Ni–Fe–P Nanocubes Derived from a Prussian Blue Analogue as an Electrocatalyst for Efficient Overall Water Splitting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xuan, Cuijuan; Wang, Jie; Xia, Weiwei

Exploring nonprecious metal electrocatalysts to replace the noble metal-based catalysts for full water electrocatalysis is still an ongoing challenge. In this work, porous structured ternary nickel–iron–phosphide (Ni–Fe–P) nanocubes were synthesized through one-step phosphidation of a Ni–Fe-based Prussian blue analogue. The Ni–Fe–P nanocubes exhibit a rough and loose porous structure on their surface under suitable phosphating temperature, which is favorable for the mass transfer and oxygen diffusion during the electrocatalysis process. As a result, Ni–Fe–P obtained at 350 °C with poorer crystallinity offers more unsaturated atoms as active sites to expedite the absorption of reactants. Additionally, the introduction of nickel improvedmore » the electronic structure and then reduced the charge-transfer resistance, which would result in a faster electron transport and an enhancement of the intrinsic electrocatalytic activities. Benefiting from the unique porous nanocubes and the chemical composition, the Ni–Fe–P nanocubes exhibit excellent hydrogen evolution reaction and oxygen evolution reaction activities in alkaline medium, with low overpotentials of 182 and 271 mV for delivering a current density of 10 mA cm–2, respectively. Moreover, the Ni–Fe–P nanocubes show outstanding stability for sustained water splitting in the two-electrode alkaline electrolyzer. Furthermore, this work not only provides a facile approach for designing bifunctional electrocatalysts but also further extends the application of metal–organic frameworks in overall water splitting.« less

Novel p-n heterojunction copper phosphide/cuprous oxide photocathode for solar hydrogen production.

PubMed

Chen, Ying-Chu; Chen, Zhong-Bo; Hsu, Yu-Kuei

2018-08-01

A Copper phosphide (Cu 3 P) micro-rod (MR) array, with coverage by an n-Cu 2 O thin layer by electrodeposition as a photocathode, has been directly fabricated on copper foil via simple electro-oxidation and phosphidation for photoelectrochemical (PEC) hydrogen production. The morphology, structure, and composition of the Cu 3 P/Cu 2 O heterostructure are systematically analyzed using a scanning electron microscope (SEM), X-ray diffraction and X-ray photoelectron spectra. The PEC measurements corroborate that the p-Cu 3 P/n-Cu 2 O heterostructural photocathode illustrates efficient charge separation and low charge transfer resistance to achieve the highest photocurrent of 430 μA cm -2 that is greater than other transition metal phosphide materials. In addition, a detailed energy diagram of the p-Cu 3 P/n-Cu 2 O heterostructure was investigated using Mott-Schottky analysis. Our study paves the way to explore phosphide-based materials in a new class for solar energy applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Thin boron phosphide coating as a corrosion-resistant layer

DOEpatents

Not Available

1982-08-25

A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anticorrosive, and providing it with unexpectedly improved photoresponsive properties.

Intentional fatal metallic phosphide poisoning in a dog--a case report.

PubMed

Nagy, Andras-Laszlo; Bolfa, Pompei; Mihaiu, Marian; Catoi, Cornel; Oros, Adrian; Taulescu, Marian; Tabaran, Flaviu

2015-07-23

Metallic phosphides are extremely toxic pesticides that are regulated in their usage. Information concerning the impact of metallic phosphides on human health is abundant. Data regarding the clinical pathology of phosphide poisoning in humans or domestic and wild animals is largely incomplete with only a few cases of metallic phosphide poisoning being reported every year, especially in humans. For the majority of cases reported in dogs the data are vague or incomplete. Here we report a complete and detailed description of pathological changes in a case of intentional metallic phosphide poisoning in a dog including an exhaustive examination of the brain. A 1 year old, male, Belgian Shepherd crossbreed dog with a clean medical history and no observed clinical signs prior to death, was submitted for post mortem examination. The dog was found dead by the owner. Near the body a suspect mix of bread, fat and a blackish powder was found. The owner announced the authorities and submitted the animal and the possible bait for forensic examination. At necropsy, multisystemic necrotic and degenerative lesions were observed. Histological exam confirmed the presence of necrotic and degenerative lesions of variable severity in all of the examined organs. The toxicological forensic examination revealed the presence of the phosphine gas in the gastric content and the bait. Metallic phosphide poisoning is a rarely reported entity, since the diagnosis of intentional poisoning with these compounds is a great challenge for forensic pathologists and toxicologists. To our knowledge, this is the first study describing the lesions completely in veterinary forensic toxicology. We assume that the toxic shows systemic endotheliotropism and damage of the endothelial cells responsible for the hemorrhagic lesions and for the secondary ischemic necrosis in various organs. This report will contribute to a better understanding of the pathogenesis in cases of acute metallic phosphide exposure in animals.

Novel tungsten phosphide embedded nitrogen-doped carbon nanotubes: A portable and renewable monitoring platform for anticancer drug in whole blood.

PubMed

Zhou, Haifeng; Ran, Guoxia; Masson, Jean-Francois; Wang, Chan; Zhao, Yuan; Song, Qijun

2018-05-15

Biosensors based on converting the concentration of analytes in complex samples into single electrochemical signals are attractive candidates as low cost, high-throughput, portable and renewable sensor platforms. Here, we describe a simple but practical analytical device for sensing an anticancer drug in whole blood, using the detection of methotrexate (MTX) as a model system. In this biosensor, a novel carbon-based composite, tungsten phosphide embedded nitrogen-doped carbon nanotubes (WP/N-CNT), was fixed to the electrode surface that supported redox cycling. The electronic transmission channel in nitrogen doped carbon nanotubes (N-CNT) and the synergistic effect of uniform distribution tungsten phosphide (WP) ensured that the electrode materials have outstanding electrical conductivity and catalytic performance. Meanwhile, the surface electronic structure also endows its surprisingly reproducible performance. To demonstrate portable operation for MTX sensing, screen printing electrodes (SPE) was modified with WP/N-CNT. The sensor exhibited low detection limits (45 nM), wide detection range (0.01-540 μM), good selectivity and long-term stability for the determination of MTX. In addition, the technique was successfully applied for the determination of MTX in whole blood. Copyright © 2018 Elsevier B.V. All rights reserved.

Phase-controlled synthesis of polymorphic tungsten diphosphide with hybridization of monoclinic and orthorhombic phases as a novel electrocatalyst for efficient hydrogen evolution

NASA Astrophysics Data System (ADS)

Pi, Mingyu; Wu, Tianli; Guo, Weimeng; Wang, Xiaodeng; Zhang, Dingke; Wang, Shuxia; Chen, Shijian

2017-05-01

The design and development of high-efficiency and non-noble-metal hydrogen evolution reaction (HER) electrocatalysts for future clean and renewable energy system has excited significant research interests over the recent years. In this communication, the polymorphic tungsten diphosphide (p-WP2) nanoparticles with mixed monoclinic (α-) and orthorhombic (β-) phases are synthesized by phase-controlled phosphidation route via vacuum capsulation and explored as a novel efficient electrocatalyst towards HER. The p-WP2 catalyst delivers superior performance with excellent stability under both acidic and alkaline conditions over its single phases of α-WP2 and β-WP2. This finding demonstrates that a highly efficient hybrid electrocatalyst can be achieved via precise composition controlling and may open up exciting opportunities for their practical applications toward energy conversion.

Photoelectrochemical cell having photoanode with thin boron phosphide coating as a corrosion resistant layer

DOEpatents

Baughman, Richard J.; Ginley, David S.

1984-01-01

A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anitcorrosive, and providing it with unexpectedly improved photoresponsive properties.

Yellow phosphorus-induced Brugada phenocopy.

PubMed

Dharanipradab, Mayakrishnan; Viswanathan, Stalin; Kumar, Gokula Raman; Krishnamurthy, Vijayalatchumy; Stanley, Daphene Divya

Metallic phosphides (of aluminum and phosphide) and yellow phosphorus are commonly used rodenticide compounds in developing countries. Toxicity of yellow phosphorus mostly pertains to the liver, kidney, heart, pancreas and the brain. Cardiotoxicity with associated Brugada ECG pattern has been reported only in poisoning with metallic phosphides. Brugada phenocopy and hepatic dysfunction were observed in a 29-year-old male following yellow phosphorus consumption. He had both type 1 (day1) and type 2 (day2) Brugada patterns in the electrocardiogram, which resolved spontaneously by the third day without hemodynamic compromise. Toxins such as aluminum and zinc phosphide have been reported to induce Brugada ECG patterns due to the generation of phosphine. We report the first case of yellow phosphorus-related Brugada phenocopy, without hemodynamic compromise or malignant arrhythmia. Copyright © 2017 Elsevier Inc. All rights reserved.

Supported organoiridium catalysts for alkane dehydrogenation

DOEpatents

Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

2013-09-03

Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

Responses of Siberian ferrets to secondary zinc phosphide poisoning

USGS Publications Warehouse

Hill, E.F.; Carpenter, J.W.

1982-01-01

The hazard of operational-type applications of zinc phosphide (Zn3P2) on a species closely related to the black-footed ferret (Mustela nigripes), was evaluated by feeding 16 Siberian ferrets (M. eversmanni) rats that had been killed by consumption of 2% zinc phosphide treated bait or by an oral dose of 40, 80, or 160 mg of Zn3P2. All ferrets accepted rats and a single emesis by each of 3 ferrets was the only evidence of acute intoxication. All ferrets learned to avoid eating gastrointestinal tracts of the rats. Subacute zinc phosphide toxicity in the ferrets was indicated by significant decreases (18-48%) in hemoglobin, increases of 35-91 % in serum iron, and elevated levels of serum globulin, cholesterol, and triglycerides. Hemoglobin/iron, urea nitrogen/creatinine, and albumin/globulin ratios also were altered by the treatments. This study demonstrated that Siberian ferrets, or other species with a sensitive emetic reflex, are afforded a degree of protection from acute zinc phosphide poisoning due to its emetic action. The importance of toxicity associated with possible respiratory, liver, and kidney damage indicated by altered blood chemistries is not known.

Noncrystalline structure of Ni-P nanoparticles prepared by liquid pulse discharge.

PubMed

Tan, Yuanyuan; Yu, Hongying; Wu, Zhonghua; Yang, Bin; Gong, Yu; Yan, Shi; Du, Rong; Chen, Zhongjun; Sun, Dongbai

2015-03-01

Noncrystalline nickel phosphide (Ni-P) nanoparticles have drawn great attention due to their high potential as catalysts. However, the structure of noncrystalline Ni-P nanoparticles is still unknown, which may shed light on explaining the catalysis mechanism of the Ni-P nanoparticles. In this paper, noncrystalline Ni-P nanoparticles were synthesized. Their morphology, particle size, element contents, local atomic structures, as well as the catalysis in the thermal decomposition of ammonium perchlorate were studied. The results demonstrate that the as-prepared Ni-P nanoparticles are spherical with an average diameter of about 13.5 nm. The Ni and P contents are, respectively, 78.15% and 21.85%. The noncrystalline nature of the as-prepared Ni-P nanoparticles can be attributed to cross-linkage between P-doping f.c.c.-like Ni centers and Ni3P-like P centers. The locally ordered Ni centers and P centers are the nuclei sites, which can explain well the origin of initial nuclei to form the crystalline phases after high-temperature annealing. The starting temperature of high-temperature decomposition of ammonium perchlorate was found having a significant decrease in the presence of the noncrystalline Ni-P nanoparticles. Therefore, the as-prepared noncrystalline Ni-P nanoparticles can be used as a potential catalyst in the thermal decomposition of ammonium perchlorate.

Nanostructured Semiconductor Electrodes for Solar Energy Conversion and Innovations in Undergraduate Chemical Lab Curriculum

NASA Astrophysics Data System (ADS)

Lee, Sudarat

This dissertation presents the methodology and discussion of preparing nanostructured, high aspect ratio p-type phosphide-based binary and ternary semiconductors via "top-down" anodic etching, a process which creates nanostructures from a large parent entity, and "bottom-up" vapor-liquid-solid growth, a mechanism which builds up small clusters of molecules block-by-block. Such architecture is particularly useful for semiconducting materials with incompatible optical absorption depth and charge carrier diffusion length, as it not only relaxes the requirement for high-grade crystalline materials, but also increases the carrier collection efficiencies for photons with energy greater than or equal to the band gap. The main focus of this dissertation is to obtain nanostructured p-type phosphide semiconductors for photoelectrochemical (PEC) cell applications. Chapter II in the thesis describes a methodology for creating high-aspect ratio p-GaP that function as a photocathode under white light illumination. Gallium phosphide (GaP, band gap: 2.26 eV) is a suitable candidate for solar conversion and energy storage due to its ability to generate large photocurrent and photovoltage to drive fuel-forming reactions. Furthermore, the band edge positions of GaP can provide sufficient kinetics for the reduction of protons and carbon dioxide. The structure is prepared by anodic etching, and the resulting macroporous structures are subsequently doped with Zn by thermally driving in Zn from conformal ZnO films prepared by atomic layer deposition (ALD). The key finding of this work is a viable doping strategy involving ALD ZnO films for making functioning p-type GaP nanostructures. Chapter III compares the GaP nanowires grown from gold (Au) and tin (Sn) VLS catalysts in a benign solid sublimation growth scheme in terms of crystal structure and photoactivity. Sn is less noble than Au, allowing complete removal of Sn metal catalysts from the nanowires through wet chemical etching which found to be useful for subsequent thermal diffusion p-type doping without fear of contaminations like Au. The main finding of this work is Sn-seeded GaP nanowires although Sn was removed without any residues and the nanowires had less twin defects than Au-seeded GaP, the nanowires were degenerately n-doped. On the contrary, Au-seeded GaP nanowires exhibited n-type characteristics with orthogonalized light absorption and charge separation. Chapter IV describes the synthesis of zinc tin phosphide (ZSP), a ternary analog of GaP comprised of low-cost, earth-abundant elements in the nanowire form using Sn nanoparticles as the VLS growth seed. The as-prepared ZSP nanowire film is capable of sustaining stable cathodic photoresponse in aqueous electrolyte under white light illumination. The nanowires were crystalized in the stoichiometric sphalerite form and possessed a direct optical band gap of ˜ 1.5 eV instead of the chalcopyrite structure that has comparable band gap energy to GaP. The Sn nanoparticles acted as the VLS seed as well as Sn source for the ZnSnP 2 nanowires growth. Chapter V summarizes the progress and findings of p-GaP nanowire array films as well as a phase non-specific, persistent ALD dye attachment scheme that facilitates hole injection into p-GaP photocathodes, extending the photon absorption range beyond its band gap. Lastly, a separate work about undergraduate chemical education development is documented in Chapter VI of this thesis. Chapter VI details the efforts made in two distinct undergraduate laboratory coursework with the intention to introduce modern microfluidics and photovoltaic technologies including multidisciplinary research experience to the undergraduate students.

Growth and Performance of GaInP/A1GaInP Visible Light Emitting Laser-Diodes,

DTIC Science & Technology

SEMICONDUCTOR LASERS, *EPITAXIAL GROWTH, ALLOYS, LAYERS, LOW PRESSURE, PRESSURE, QUALITY, ROOM TEMPERATURE, SUBSTRATES, GALLIUM PHOSPHIDES, INDIUM PHOSPHIDES, THERMAL PROPERTIES, ENERGY GAPS, ENERGY BANDS, VAPOR PHASES.

Light Absorbers and Catalysts for Solar to Fuel Conversion

NASA Astrophysics Data System (ADS)

Kornienko, Nikolay I.

Increasing fossil fuel consumption and the resulting consequences to the environment has propelled research into means of utilizing alternative, clean energy sources. Solar power is among the most promising of renewable energy sources but must be converted into an energy dense medium such as chemical bonds to render it useful for transport and energy storage. Photoelectrochemistry (PEC), the splitting of water into oxygen and hydrogen fuel or reducing CO 2 to hydrocarbon fuels via sunlight is a promising approach towards this goal. Photoelectrochemical systems are comprised of several components, including light absorbers and catalysts. These parts must all synergistically function in a working device. Therefore, the continual development of each component is crucial for the overall goal. For PEC systems to be practical for large scale use, the must be efficient, stable, and composed of cost effective components. To this end, my work focused on the development of light absorbing and catalyst components of PEC solar to fuel converting systems. In the direction of light absorbers, I focused of utilizing Indium Phosphide (InP) nanowires (NWs) as photocathodes. I first developed synthetic techniques for InP NW solution phase and vapor phase growth. Next, I developed light absorbing photocathodes from my InP NWs towards PEC water splitting cells. I studied cobalt sulfide (CoSx) as an earth abundant catalyst for the reductive hydrogen evolution half reaction. Using in situ spectroscopic techniques, I elucidated the active structure of this catalyst and offered clues to its high activity. In addition to hydrogen evolution catalysts, I established a new generation of earth abundant catalysts for CO2 reduction to CO fuel/chemical feedstock. I first worked with molecularly tunable homogeneous catalysts that exhibited high selectivity for CO2 reduction in non-aqueous media. Next, in order to retain molecular tunability while achieving stability and efficiency in aqueous solvents, I aimed to heterogenize a class of molecular porphyrin catalysts into a 3D mesoscopic porous catalytic structure in the form of a metal-organic framework (MOF). To do so, I initially developed a growth for thin film MOFs that were embedded with catalytic groups in their linkers. Next, I utilized these thin film MOFs grown on conductive substrates and functionalized with cobalt porphyrin units as 3D porous CO2 reduction catalysts. This new class of catalyst exhibited high efficiency, selectivity, and stability in neutral pH aqueous electrolytes. Finally, as a last chapter of my work, I explored hybrid inorganic/biological CO2 reduction pathways. Specifically, I used time-resolved spectroscopic and biochemical techniques to investigate charge transfer pathways from light absorber to CO2-derived acetate in acetogenic self-sensitized bacteria.

New reactions involving the oxidative O-, N-, and C-phosphorylation of organic compounds by phosphorus and phosphides in the presence of metal complexes

NASA Astrophysics Data System (ADS)

Dorfman, Ya A.; Aleshkova, M. M.; Polimbetova, G. S.; Levina, L. V.; Petrova, T. V.; Abdreimova, R. R.; Doroshkevich, D. M.

1993-09-01

The mechanisms of new catalytic reactions leading to the formation of di-, and tri-alkyl phosphates, di- and tri-alkyl phosphites, phosphoramidites, phosphazenes, phosphines, and phosphine oxides from hydrogen, copper, and zinc phosphides and white and red phosphorus are analysed. The mechanisms of the activation of the reactants by metal complexes and of the reactions involving the oxidative P-O, P-N, and P-C coupling of organic compounds to phosphorus and phosphides are considered. The bibliography includes 124 references.

Low Pressure Synthesis of Indium Phosphide,

DTIC Science & Technology

1982-04-01

UNCLASSIFIED F/G 713 M EEEEEEEEEII MEEMMMME W , 2~ h IW 𔃼 * ).I 2 MICROCOP RESOWI1OW TWS CHAT . . WROmNA RUIEJ MT STHDMS-W3-ALORMO TNDM- m &6.4. MM RO - TMS...pNode . M-V Semiconductor compound ’S.T o a.ek* !cm .. EImd’b lc a ..... . P Pocry sline large g rain .bgot of indiumn phosphide have been synthe- simed...indium temperature of 1003"C. 2. BACKGROUND .r. Indium phosphide is a compound composed of elements from the third and fifth columns of the periodic

Thermal Properties and Phonon Spectral Characterization of Synthetic Boron Phosphide for High Thermal Conductivity Applications.

PubMed

Kang, Joon Sang; Wu, Huan; Hu, Yongjie

2017-12-13

Heat dissipation is an increasingly critical technological challenge in modern electronics and photonics as devices continue to shrink to the nanoscale. To address this challenge, high thermal conductivity materials that can efficiently dissipate heat from hot spots and improve device performance are urgently needed. Boron phosphide is a unique high thermal conductivity and refractory material with exceptional chemical inertness, hardness, and high thermal stability, which holds high promises for many practical applications. So far, however, challenges with boron phosphide synthesis and characterization have hampered the understanding of its fundamental properties and potential applications. Here, we describe a systematic thermal transport study based on a synergistic synthesis-experimental-modeling approach: we have chemically synthesized high-quality boron phosphide single crystals and measured their thermal conductivity as a record-high 460 W/mK at room temperature. Through nanoscale ballistic transport, we have, for the first time, mapped the phonon spectra of boron phosphide and experimentally measured its phonon mean free-path spectra with consideration of both natural and isotope-pure abundances. We have also measured the temperature- and size-dependent thermal conductivity and performed corresponding calculations by solving the three-dimensional and spectral-dependent phonon Boltzmann transport equation using the variance-reduced Monte Carlo method. The experimental results are in good agreement with that predicted by multiscale simulations and density functional theory, which together quantify the heat conduction through the phonon mode dependent scattering process. Our finding underscores the promise of boron phosphide as a high thermal conductivity material for a wide range of applications, including thermal management and energy regulation, and provides a detailed, microscopic-level understanding of the phonon spectra and thermal transport mechanisms of boron phosphide. The present study paves the way toward the establishment of a new framework, based on the phonon spectra-material structure relationship, for the rational design of high thermal conductivity materials and nano- to multiscale devices.

Aluminum phosphide

Integrated Risk Information System (IRIS)

Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

Indium phosphide nanowires and their applications in optoelectronic devices.

PubMed

Zafar, Fateen; Iqbal, Azhar

2016-03-01

Group IIIA phosphide nanocrystalline semiconductors are of great interest among the important inorganic materials because of their large direct band gaps and fundamental physical properties. Their physical properties are exploited for various potential applications in high-speed digital circuits, microwave and optoelectronic devices. Compared to II-VI and I-VII semiconductors, the IIIA phosphides have a high degree of covalent bonding, a less ionic character and larger exciton diameters. In the present review, the work done on synthesis of III-V indium phosphide (InP) nanowires (NWs) using vapour- and solution-phase approaches has been discussed. Doping and core-shell structure formation of InP NWs and their sensitization using higher band gap semiconductor quantum dots is also reported. In the later section of this review, InP NW-polymer hybrid material is highlighted in view of its application as photodiodes. Lastly, a summary and several different perspectives on the use of InP NWs are discussed.

Reducing fischer-tropsch catalyst attrition losses in high agitation reaction systems

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2001-01-01

A method for reducing catalyst attrition losses in hydrocarbon synthesis processes conducted in high agitation reaction systems; a method of producing an attrition-resistant catalyst; a catalyst produced by such method; a method of producing an attrition-resistant catalyst support; and a catalyst support produced by such method. The inventive method of reducing catalyst attrition losses comprises the step of reacting a synthesis gas in a high agitation reaction system in the presence of a catalyst. In one aspect, the catalyst preferably comprises a .gamma.-alumina support including an amount of titanium effective for increasing the attrition resistance of the catalyst. In another aspect, the catalyst preferably comprises a .gamma.-alumina support which has been treated, after calcination, with an acidic, aqueous solution. The acidic aqueous solution preferably has a pH of not more than about 5. In another aspect, the catalyst preferably comprises cobalt on a .gamma.-alumina support wherein the cobalt has been applied to the .gamma.-alumina support by totally aqueous, incipient wetness-type impregnation. In another aspect, the catalyst preferably comprises cobalt on a .gamma.-alumina support with an amount of a lanthana promoter effective for increasing the attrition resistance of the catalyst. In another aspect, the catalyst preferably comprises a .gamma.-alumina support produced from boehmite having a crystallite size, in the 021 plane, in the range of from about 30 to about 55 .ANG.ngstrons. In another aspect, the inventive method of producing an attrition-resistant catalyst comprises the step of treating a .gamma.-alumina support, after calcination of and before adding catalytic material to the support, with an acidic solution effective for increasing the attrition resistance of the catalyst. In another aspect, the inventive method of producing an attrition-resistant catalyst support comprises the step of treating calcined .gamma.-alumina with an acidic, aqueous solution effective for increasing the attrition resistance of the .gamma.-alumina.

Durability testing at one atmosphere of advanced catalysts and catalyst supports for automotive gas turbine engine combustors, part 1

NASA Technical Reports Server (NTRS)

Heck, R. M.; Chang, M.; Hess, H.; Carrubba, R.

1977-01-01

The durability of catalysts and catalyst supports in a combustion environment was experimentally demonstrated. A test of 1000 hours duration was completed with two catalysts, using diesel fuel and operating at catalytically supported thermal combustion conditions. The performance of the catalysts was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. The test catalysts proved to be capable of low emissions operation after 1000 hours diesel aging, with no apparent physical degradation of the catalyst support.

Clinical characteristics of zinc phosphide poisoning in Thailand.

PubMed

Trakulsrichai, Satariya; Kosanyawat, Natcha; Atiksawedparit, Pongsakorn; Sriapha, Charuwan; Tongpoo, Achara; Udomsubpayakul, Umaporn; Rittilert, Panee; Wananukul, Winai

2017-01-01

The objectives of this study were to describe the clinical characteristics and outcomes of poisoning by zinc phosphide, a common rodenticide in Thailand, and to evaluate whether these outcomes can be prognosticated by the clinical presentation. A 3-year retrospective cohort study was performed using data from the Ramathibodi Poison Center Toxic Exposure Surveillance System. In total, 455 poisonings were identified. Most were males (60.5%) and from the central region of Thailand (71.0%). The mean age was 39.91±19.15 years. The most common route of exposure was oral (99.3%). Most patients showed normal vital signs, oxygen saturation, and consciousness at the first presentation. The three most common clinical presentations were gastrointestinal (GI; 68.8%), cardiovascular (22.0%), and respiratory (13.8%) signs and symptoms. Most patients had normal blood chemistry laboratory results and chest X-ray findings at presentation. The median hospital stay was 2 days, and the mortality rate was 7%. Approximately 70% of patients underwent GI decontamination, including gastric lavage and a single dose of activated charcoal. In all, 31 patients were intubated and required ventilator support. Inotropic drugs were given to 4.2% of patients. Four moribund patients also received hyperinsulinemia-euglycemia therapy and intravenous hydrocortisone; however, all died. Patients who survived and died showed significant differences in age, duration from taking zinc phosphide to hospital presentation, abnormal vital signs at presentation (tachycardia, low blood pressure, and tachypnea), acidosis, hypernatremia, hyperkalemia, in-hospital acute kidney injury, in-hospital hypoglycemia, endotracheal tube intubation, and inotropic requirement during hospitalization ( P <0.05). Zinc phosphide poisoning causes fatalities. Most patients have mild symptoms, and GI symptoms are the most common. Patients who present with abnormal vital signs or electrolytes might have more severe poisoning and should be closely monitored and aggressively treated. All patients should be observed in the hospital for 2 days and followed up for cardiovascular and respiratory symptoms, electrolyte balances, kidney function, and blood glucose.

Fischer–Tropsch synthesis: Effect of ammonia on supported cobalt catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pendyala, Venkat Ramana Rao; Jacobs, Gary; Bertaux, Clement

The effect of ammonia in syngas on the performance of various supported cobalt catalysts (i.e., Al 2O 3, TiO 2 and SiO 2) was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR). The addition of ammonia (10 ppmv NH 3) caused a significant deactivation for all supported cobalt catalysts, but the rate of deactivation was higher for the silica-supported catalysts relative to the alumina and titania-supported catalysts used in this work. Ammonia addition had a positive effect on product selectivity (i.e., lower light gas products and higher C 5+) for alumina and titania-supported catalysts compared tomore » ammonia free conditions, whereas, the addition of ammonia increased lighter hydrocarbon (C 1-C 4) products and decreased higher hydrocarbon (C 5+) selectivity compared to ammonia-free synthesis conditions for the silica-supported catalyst. For alumina and titania-supported catalysts, the activity almost recovered with mild in-situ hydrogen treatment of the ammonia exposed catalysts. For the silica-supported catalyst, the loss of activity is somewhat irreversible (i.e., cannot be regained after the mild hydrogen treatment). Addition of ammonia led to a significant loss in BET surface area and changes in pore diameter (consistent with pore collapse of a fraction of pores into the microporous range as described in the literature), as well as formation of catalytically inactive cobalt support compounds for the silica-supported catalyst. On the other hand, the pore characteristics of alumina and titania-supported catalysts were not significantly changed. In conclusion, XANES results of the ammonia exposed silica-supported catalysts further confirm the formation of cobalt-support compounds (cobalt silicates).« less

Fischer–Tropsch synthesis: Effect of ammonia on supported cobalt catalysts

DOE PAGES

Pendyala, Venkat Ramana Rao; Jacobs, Gary; Bertaux, Clement; ...

2016-02-22

The effect of ammonia in syngas on the performance of various supported cobalt catalysts (i.e., Al 2O 3, TiO 2 and SiO 2) was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR). The addition of ammonia (10 ppmv NH 3) caused a significant deactivation for all supported cobalt catalysts, but the rate of deactivation was higher for the silica-supported catalysts relative to the alumina and titania-supported catalysts used in this work. Ammonia addition had a positive effect on product selectivity (i.e., lower light gas products and higher C 5+) for alumina and titania-supported catalysts compared tomore » ammonia free conditions, whereas, the addition of ammonia increased lighter hydrocarbon (C 1-C 4) products and decreased higher hydrocarbon (C 5+) selectivity compared to ammonia-free synthesis conditions for the silica-supported catalyst. For alumina and titania-supported catalysts, the activity almost recovered with mild in-situ hydrogen treatment of the ammonia exposed catalysts. For the silica-supported catalyst, the loss of activity is somewhat irreversible (i.e., cannot be regained after the mild hydrogen treatment). Addition of ammonia led to a significant loss in BET surface area and changes in pore diameter (consistent with pore collapse of a fraction of pores into the microporous range as described in the literature), as well as formation of catalytically inactive cobalt support compounds for the silica-supported catalyst. On the other hand, the pore characteristics of alumina and titania-supported catalysts were not significantly changed. In conclusion, XANES results of the ammonia exposed silica-supported catalysts further confirm the formation of cobalt-support compounds (cobalt silicates).« less

Catalysis on Single Supported Atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeBusk, Melanie Moses; Narula, Chaitanya Kumar

2015-01-01

The highly successful application of supported metals as heterogeneous catalysts in automotive catalysts, fuel cells, and other multitudes of industrial processes have led to extensive efforts to understand catalyst behavior at the nano-scale. Recent discovery of simple wet methods to prepare single supported atoms, the smallest nano-catalyst, has allowed for experimental validation of catalytic activity of a variety of catalysts and potential for large scale production for such catalysts for industrial processes. In this chapter, we summarize the synthetic and structural aspects of single supported atoms. We also present proposed mechanisms for the activity of single supported catalysts where conventionalmore » mechanisms cannot operate due to lack of M-M bonds in the catalysts.« less

Concept Definition for the Pest Management Component of the Pollution Abatement Management System (PAMS).

DTIC Science & Technology

1982-01-01

able to obtain * Aluminum phosphide, Bromacil, Carbaryl (Sevin), Chlordane, Chlorpyrifos (Oursban), Diazinon, Dichlorovos (DODYP), Malathion, Paraquat...Pentachloro- phenol (PCP), Propoxur (Baygon), Thiram, strychnine/strychnine sulfate, zinc phosphide, and 2,4-D. 10 sufficient data to respond to

Process of making supported catalyst

DOEpatents

Schwarz, James A.; Subramanian, Somasundaram

1992-01-01

Oxide supported metal catalysts have an additional metal present in intimate association with the metal catalyst to enhance catalytic activity. In a preferred mode, iridium or another Group VIII metal catalyst is supported on a titania, alumina, tungsten oxide, silica, or composite oxide support. Aluminum ions are readsorbed onto the support and catalyst, and reduced during calcination. The aluminum can be added as aluminum nitrate to the iridium impregnate solution, e.g. chloroiridic acid.

Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

PubMed Central

Bagheri, Samira; Muhd Julkapli, Nurhidayatullaili; Bee Abd Hamid, Sharifah

2014-01-01

The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2 was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2 supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2 as a support material for heterogeneous catalysts and its potential applications. PMID:25383380

Visible light electroluminescent diodes of indium-gallium phosphide

NASA Technical Reports Server (NTRS)

Clough, R.; Richman, D.; Tietjen, J.

1970-01-01

Vapor deposition and acceptor impurity diffusion techniques are used to prepare indium-gallium phosphide junctions. Certain problems in preparation are overcome by altering gas flow conditions and by increasing the concentration of phosphine in the gas. A general formula is given for the alloy's composition.

A case of accidental fatal aluminum phosphide poisoning involving humans and dogs.

PubMed

Behera, Chittaranjan; Krishna, Karthik; Bhardwaj, Daya Nand; Rautji, Ravi; Kumar, Arvind

2015-05-01

Aluminum phosphide is one of the commonest poisons encountered in agricultural areas, and manner of death in the victims is often suicidal and rarely homicidal or accidental. This paper presents an unusual case, where two humans (owner and housemaid) and eight dogs were found dead in the morning hours inside a room of a house, used as shelter for stray dogs. There was allegation by the son of the owner that his father had been killed. Crime scene visit by forensic pathologists helped to collect vital evidence. Autopsies of both the human victims and the dogs were conducted. Toxicological analysis of viscera, vomitus, leftover food, and chemical container at the crime scene tested positive for aluminum phosphide. The cause of death in both humans and dogs was aluminum phosphide poisoning. Investigation by police and the forensic approach to the case helped in ascertaining the manner of death, which was accidental. © 2015 American Academy of Forensic Sciences.

Effect of dislocations on the open-circuit voltage, short-circuit current and efficiency of heteroepitaxial indium phosphide solar cells

NASA Technical Reports Server (NTRS)

Jain, Raj K.; Flood, Dennis J.

1990-01-01

Excellent radiation resistance of indium phosphide solar cells makes them a promising candidate for space power applications, but the present high cost of starting substrates may inhibit their large scale use. Thin film indium phosphide cells grown on Si or GaAs substrates have exhibited low efficiencies, because of the generation and propagation of large number of dislocations. Dislocation densities were calculated and its influence on the open circuit voltage, short circuit current, and efficiency of heteroepitaxial indium phosphide cells was studied using the PC-1D. Dislocations act as predominant recombination centers and are required to be controlled by proper transition layers and improved growth techniques. It is shown that heteroepitaxial grown cells could achieve efficiencies in excess of 18 percent AMO by controlling the number of dislocations. The effect of emitter thickness and surface recombination velocity on the cell performance parameters vs. dislocation density is also studied.

Indium phosphide nanowires and their applications in optoelectronic devices

PubMed Central

Zafar, Fateen

2016-01-01

Group IIIA phosphide nanocrystalline semiconductors are of great interest among the important inorganic materials because of their large direct band gaps and fundamental physical properties. Their physical properties are exploited for various potential applications in high-speed digital circuits, microwave and optoelectronic devices. Compared to II–VI and I–VII semiconductors, the IIIA phosphides have a high degree of covalent bonding, a less ionic character and larger exciton diameters. In the present review, the work done on synthesis of III–V indium phosphide (InP) nanowires (NWs) using vapour- and solution-phase approaches has been discussed. Doping and core–shell structure formation of InP NWs and their sensitization using higher band gap semiconductor quantum dots is also reported. In the later section of this review, InP NW-polymer hybrid material is highlighted in view of its application as photodiodes. Lastly, a summary and several different perspectives on the use of InP NWs are discussed. PMID:27118920

Rational approach to polymer-supported catalysts: synergy between catalytic reaction mechanism and polymer design.

PubMed

Madhavan, Nandita; Jones, Christopher W; Weck, Marcus

2008-09-01

Supported catalysis is emerging as a cornerstone of transition metal catalysis, as environmental awareness necessitates "green" methodologies and transition metal resources become scarcer and more expensive. Although these supported systems are quite useful, especially in their capacity for transition metal catalyst recycling and recovery, higher activity and selectivity have been elusive compared with nonsupported catalysts. This Account describes recent developments in polymer-supported metal-salen complexes, which often surpass nonsupported analogues in catalytic activity and selectivity, demonstrating the effectiveness of a systematic, logical approach to designing supported catalysts from a detailed understanding of the catalytic reaction mechanism. Over the past few decades, a large number of transition metal complex catalysts have been supported on a variety of materials ranging from polymers to mesoporous silica. In particular, soluble polymer supports are advantageous because of the development of controlled and living polymerization methods that are tolerant to a wide variety of functional groups, including controlled radical polymerizations and ring-opening metathesis polymerization. These methods allow for tuning the density and structure of the catalyst sites along the polymer chain, thereby enabling the development of structure-property relationships between a catalyst and its polymer support. The fine-tuning of the catalyst-support interface, in combination with a detailed understanding of catalytic reaction mechanisms, not only permits the generation of reusable and recyclable polymer-supported catalysts but also facilitates the design and realization of supported catalysts that are significantly more active and selective than their nonsupported counterparts. These superior supported catalysts are accessible through the optimization of four basic variables in their design: (i) polymer backbone rigidity, (ii) the nature of the linker, (iii) catalyst site density, and (iv) the nature of the catalyst attachment. Herein, we describe the design of polymer supports tuned to enhance the catalytic activity or decrease, or even eliminate, decomposition pathways of salen-based transition metal catalysts that follow either a monometallic or a bimetallic reaction mechanism. These findings result in the creation of some of the most active and selective salen catalysts in the literature.

Oxidation of methane over palladium catalysts: effect of the support.

PubMed

Escandón, Lara S; Ordóñez, Salvador; Vega, Aurelio; Díez, Fernando V

2005-01-01

This work is focused on the deep catalytic oxidation of methane over supported palladium catalysts. The influences of the metal loading, oxidation state of palladium, nature of supports, presence of promoters in the supports (for zirconia-based supports), and thermal stability have been studied experimentally. Catalysts were prepared by incipient wetness of commercially available supports with aqueous solutions of palladium nitrate. For gamma-alumina support, it was observed that the optimal amount of palladium is between 0.5% and 2%, with higher amounts leading to a loss in specific activity. Concerning the oxidation state of the catalyst, it is concluded that for all the supports tested in the present work, a reduction of the catalyst is not needed, yielding the same conversion at steady state catalysts reduced and oxidised. The thermal stability of various supported catalysts were also studied, zirconia supports being the most active. These supports, specially Y-modified zirconia support, do not suffer appreciable deactivation below 500 degrees C.

Technology for advanced liquefaction processes: Coal/waste coprocessing studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cugini, A.V.; Rothenberger, K.S.; Ciocco, M.V.

1995-12-31

The efforts in this project are directed toward three areas: (1) novel catalyst (supported and unsupported) research and development, (2) study and optimization of major operating parameters (specifically pressure), and (3) coal/waste coprocessing. The novel catalyst research and development activity has involved testing supported catalysts, dispersed catalysts, and use of catalyst testing units to investigate the effects of operating parameters (the second area) with both supported and unsupported catalysts. Several supported catalysts were tested in a simulated first stage coal liquefaction application at 404{degrees}C during this performance period. A Ni-Mo hydrous titanate catalyst on an Amocat support prepared by Sandiamore » National laboratories was tested. Other baseline experiments using AO-60 and Amocat, both Ni-Mo/Al{sub 2}O{sub 3} supported catalysts, were also made. These experiments were short duration (approximately 12 days) and monitored the initial activity of the catalysts. The results of these tests indicate that the Sandia catalyst performed as well as the commercially prepared catalysts. Future tests are planned with other Sandia preparations. The dispersed catalysts tested include sulfated iron oxide, Bayferrox iron oxide (iron oxide from Miles, Inc.), and Bailey iron oxide (micronized iron oxide from Bailey, Inc.). The effects of space velocity, temperature, and solvent-to-coal ratio on coal liquefaction activity with the dispersed catalysts were investigated. A comparison of the coal liquefaction activity of these catalysts relative to iron catalysts tested earlier, including FeOOH-impregnated coal, was made. These studies are discussed.« less

Strained quantum well photovoltaic energy converter

NASA Technical Reports Server (NTRS)

Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

1998-01-01

An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

Sinterless Fabrication Of Contact Pads On InP Devices

NASA Technical Reports Server (NTRS)

Weizer, Victor G.; Fatemi, Navid S.; Korenyi-Both, Andras L.

1995-01-01

Research has shown that with proper choice of material, low-resistance contact pads deposited on solar cells and other devices by improved technique that does not involve sintering. Research directed at understanding mechanisms involved in contact-sintering process has resulted in identification of special group of materials that includes phosphides of gold, silver, and nickel; specifically, Au(2)P(3), AgP(2), and Ni(3)P. Incorporation of phosphide interlayer substantially reduces resistivity between gold current-carrying layer and indium phosphide substrate. Further research indicated only very thin interlayer of any of these compounds needed to obtain low contact resistance, without subjecting contact to destructive sintering process.

Catalyst system comprising a first catalyst system tethered to a supported catalyst

DOEpatents

Angelici, Robert J.; Gao, Hanrong

1998-08-04

The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.

Catalyst system comprising a first catalyst system tethered to a supported catalyst

DOEpatents

Angelici, R.J.; Gao, H.

1998-08-04

The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilication, olefin oxidation, isomerization, hydrocyanidation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical. 2 figs.

Immobilization of molecular catalysts in supported ionic liquid phases.

PubMed

Van Doorslaer, Charlie; Wahlen, Joos; Mertens, Pascal; Binnemans, Koen; De Vos, Dirk

2010-09-28

In a supported ionic liquid phase (SILP) catalyst system, an ionic liquid (IL) film is immobilized on a high-surface area porous solid and a homogeneous catalyst is dissolved in this supported IL layer, thereby combining the attractive features of homogeneous catalysts with the benefits of heterogeneous catalysts. In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed. In the first part, general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic liquid and reaction conditions. Secondly, organic reactions in which SILP technology is applied to improve the performance of homogeneous transition-metal catalysts are presented: hydroformylation, metathesis reactions, carbonylation, hydrogenation, hydroamination, coupling reactions and asymmetric reactions.

Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

PubMed

Li, Kuo-Tseng; Wu, Ling-Huey

2017-05-05

Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

Hydrocarbon reforming catalyst material and configuration of the same

DOEpatents

Singh, Prabhakar; Shockling, Larry A.; George, Raymond A.; Basel, Richard A.

1996-01-01

A hydrocarbon reforming catalyst material comprising a catalyst support impregnated with catalyst is provided for reforming hydrocarbon fuel gases in an electrochemical generator. Elongated electrochemical cells convert the fuel to electrical power in the presence of an oxidant, after which the spent fuel is recirculated and combined with a fresh hydrocarbon feed fuel forming the reformable gas mixture which is fed to a reforming chamber containing a reforming catalyst material, where the reforming catalyst material includes discrete passageways integrally formed along the length of the catalyst support in the direction of reformable gas flow. The spent fuel and/or combusted exhaust gases discharged from the generator chamber transfer heat to the catalyst support, which in turn transfers heat to the reformable gas and to the catalyst, preferably via a number of discrete passageways disposed adjacent one another in the reforming catalyst support. The passageways can be slots extending inwardly from an outer surface of the support body, which slots are partly defined by an exterior confining wall. According to a preferred embodiment, the catalyst support is non-rigid, porous, fibrous alumina, wherein the fibers are substantially unsintered and compressible, and the reforming catalyst support is impregnated, at least in the discrete passageways with Ni and MgO, and has a number of internal slot passageways for reformable gas, the slot passageways being partly closed by a containing outer wall.

Hydrocarbon reforming catalyst material and configuration of the same

DOEpatents

Singh, P.; Shockling, L.A.; George, R.A.; Basel, R.A.

1996-06-18

A hydrocarbon reforming catalyst material comprising a catalyst support impregnated with catalyst is provided for reforming hydrocarbon fuel gases in an electrochemical generator. Elongated electrochemical cells convert the fuel to electrical power in the presence of an oxidant, after which the spent fuel is recirculated and combined with a fresh hydrocarbon feed fuel forming the reformable gas mixture which is fed to a reforming chamber containing a reforming catalyst material, where the reforming catalyst material includes discrete passageways integrally formed along the length of the catalyst support in the direction of reformable gas flow. The spent fuel and/or combusted exhaust gases discharged from the generator chamber transfer heat to the catalyst support, which in turn transfers heat to the reformable gas and to the catalyst, preferably via a number of discrete passageways disposed adjacent one another in the reforming catalyst support. The passageways can be slots extending inwardly from an outer surface of the support body, which slots are partly defined by an exterior confining wall. According to a preferred embodiment, the catalyst support is non-rigid, porous, fibrous alumina, wherein the fibers are substantially unsintered and compressible, and the reforming catalyst support is impregnated, at least in the discrete passageways with Ni and MgO, and has a number of internal slot passageways for reformable gas, the slot passageways being partly closed by a containing outer wall. 5 figs.

Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

PubMed

Baran, Talat

2017-06-15

In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Hydrogen production by steam reforming of liquefied natural gas over a nickel catalyst supported on mesoporous alumina xerogel

NASA Astrophysics Data System (ADS)

Seo, Jeong Gil; Youn, Min Hye; Cho, Kyung Min; Park, Sunyoung; Song, In Kyu

Mesoporous alumina xerogel (A-SG) is prepared by a sol-gel method for use as a support for a nickel catalyst. The Ni/A-SG catalyst is then prepared by an impregnation method, and is applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of the mesoporous alumina xerogel support on the catalytic performance of Ni/A-SG catalyst is investigated. For the purpose of comparison, a nickel catalyst supported on commercial alumina (A-C) is also prepared by an impregnation method (Ni/A-C). Both the hydroxyl-rich surface and the electron-deficient sites of the A-SG support enhance the dispersion of the nickel species on the support during the calcination step. The formation of the surface nickel aluminate phase in the Ni/A-SG catalyst remarkably increases the reducibility and stability of the catalyst. Furthermore, the high-surface area and the well-developed mesoporosity of the Ni/A-SG catalyst enhance the gasification of surface hydrocarbons that are adsorbed in the reaction. In the steam reforming of LNG, the Ni/A-SG catalyst exhibits a better catalytic performance than the Ni/A-C catalyst in terms of LNG conversion and hydrogen production. Moreover, the Ni/A-SG catalyst shows strong resistance toward catalyst deactivation.

Black-tailed prairie dog populations one year after treatment with rodenticides

Treesearch

Anthony D. Apa; Daniel W. Uresk; Raymond L. Linder

1990-01-01

Three rodenticide treatments, zinc phosphide with prebait, strychnine with prebait, and strychnine without prebait, were applied to black-tailed prairie dog (Cynomys ludovicianus) colonies in west central South Dakota. Results were compared immediately posttreatment and for one year after application. Zinc phosphide was the most effective for...

Highly dispersed metal catalyst

DOEpatents

Xiao, Xin; West, William L.; Rhodes, William D.

2016-11-08

A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

Electrochemical Catalyst-Support Effects and Their Stabilizing Role for IrOx Nanoparticle Catalysts during the Oxygen Evolution Reaction.

PubMed

Oh, Hyung-Suk; Nong, Hong Nhan; Reier, Tobias; Bergmann, Arno; Gliech, Manuel; Ferreira de Araújo, Jorge; Willinger, Elena; Schlögl, Robert; Teschner, Detre; Strasser, Peter

2016-09-28

Redox-active support materials can help reduce the noble-metal loading of a solid chemical catalyst while offering electronic catalyst-support interactions beneficial for catalyst durability. This is well known in heterogeneous gas-phase catalysis but much less discussed for electrocatalysis at electrified liquid-solid interfaces. Here, we demonstrate experimental evidence for electronic catalyst-support interactions in electrochemical environments and study their role and contribution to the corrosion stability of catalyst/support couples. Electrochemically oxidized Ir oxide nanoparticles, supported on high surface area carbons and oxides, were selected as model catalyst/support systems for the electrocatalytic oxygen evolution reaction (OER). First, the electronic, chemical, and structural state of the catalyst/support couple was compared using XANES, EXAFS, TEM, and depth-resolved XPS. While carbon-supported oxidized Ir particle showed exclusively the redox state (+4), the Ir/IrOx/ATO system exhibited evidence of metal/metal-oxide support interactions (MMOSI) that stabilized the metal particles on antimony-doped tin oxide (ATO) in sustained lower Ir oxidation states (Ir(3.2+)). At the same time, the growth of higher valent Ir oxide layers that compromise catalyst stability was suppressed. Then the electrochemical stability and the charge-transfer kinetics of the electrocatalysts were evaluated under constant current and constant potential conditions, where the analysis of the metal dissolution confirmed that the ATO support mitigates Ir(z+) dissolution thanks to a stronger MMOSI effect. Our findings raise the possibility that MMOSI effects in electrochemistry-largely neglected in the past-may be more important for a detailed understanding of the durability of oxide-supported nanoparticle OER catalysts than previously thought.

Effect of EtOH/MgCl(2) molar ratios on the catalytic properties of MgCl(2)-SiO(2)/TiCl(4) Ziegler-Natta catalyst for ethylene polymerization.

PubMed

Patthamasang, Supanan; Jongsomjit, Bunjerd; Praserthdam, Piyasan

2011-09-29

MgCl(2)-SiO(2)/TiCl(4) Ziegler-Natta catalysts for ethylene polymerization were prepared by impregnation of MgCl(2) on SiO(2) in heptane and further treatment with TiCl(4). MgCl(2)·nEtOH adduct solutions were prepared with various EtOH/MgCl(2) molar ratios for preparation of the MgCl(2)-supported and MgCl(2)-SiO(2)-supported catalysts in order to investigate the effect on polymerization performance of both catalyst systems. The catalytic activities for ethylene polymerization decreased markedly with increased molar ratios of [EtOH]/[MgCl(2)] for the MgCl(2)-supported catalysts, while for the bi-supported catalysts, the activities only decreased slightly. The MgCl(2)-SiO(2)-supported catalyst had relatively constant activity, independent of the [EtOH]/[MgCl(2)] ratio. The lower [EtOH]/[MgCl(2)] in MgCl(2)-supported catalyst exhibited better catalytic activity. However, for the MgCl(2)-SiO(2)-supported catalyst, MgCl(2) can agglomerate on the SiO(2) surface at low [EtOH]/[MgCl(2)] thus not being not suitable for TiCl(4) loading. It was found that the optimized [EtOH]/[MgCl(2)] value for preparation of bi-supported catalysts having high activity and good spherical morphology with little agglomerated MgCl(2) was 7. Morphological studies indicated that MgCl(2)-SiO(2)-supported catalysts have good morphology with spherical shapes that retain the morphology of SiO(2). The BET measurement revealed that pore size is the key parameter dictating polymerization activity. The TGA profiles of the bi-supported catalyst also confirmed that it was more stable than the mono-supported catalyst, especially in the ethanol removal region.

Oxidative coupling of methane over supported La{sub 2}O{sub 3} and La-promoted MgO catalysts: Influence of catalyst-support interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, V.R.; Mulla, S.A.R.; Uphade, B.S.

1997-06-01

Methane-to-C{sub 2}-hydrocarbon conversion activity and selectivity (or yield) of MgO and La-promoted MgO catalysts in the oxidative coupling of methane and strong basicity of the catalysts are decreased appreciably when these catalysts are deposited on commonly used commercial low surface area porous catalyst carriers containing Al{sub 2}O{sub 3}, SiO{sub 2}, SiC, or ZrO{sub 2} + HfO{sub 2} as the main components. The decrease in the strong basicity and catalytic activity/selectivity or yield is mostly due to strong chemical interactions between the active catalyst component (viz., MgO and La{sub 2}O{sub 3}) and the reactive components of the catalyst support (viz., Al{submore » 2}O{sub 3} and SiO{sub 2}), resulting in the formation of catalytically inactive binary metal oxides on the support surface. However, the influence of support on the activity/selectivity of La{sub 2}O{sub 3} is relatively very small, and also the chemical interactions of La{sub 2}O{sub 3} with the supports (except that containing a high concentration of SiO{sub 2}) are almost absent. The catalyst-support interactions are thus found to be strongly dependent upon the nature (chemical composition) of both catalyst and support. For developing better supported catalysts for the oxidative coupling of methane, supported La{sub 2}O{sub 3} with some promoters shows high promise.« less

System and method for controlling hydrogen elimination during carbon nanotube synthesis from hydrocarbons

DOEpatents

Reilly, Peter T. A.

2010-03-23

A system and method for producing carbon nanotubes by chemical vapor deposition includes a catalyst support having first and second surfaces. The catalyst support is capable of hydrogen transport from the first to the second surface. A catalyst is provided on the first surface of the catalyst support. The catalyst is selected to catalyze the chemical vapor deposition formation of carbon nanotubes. A fuel source is provided for supplying fuel to the catalyst.

Development of gallium aluminum phosphide electroluminescent diodes

NASA Technical Reports Server (NTRS)

Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

1972-01-01

Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function.

PubMed

Adolfsson, Karl; Schneider, Martina; Hammarin, Greger; Häcker, Udo; Prinz, Christelle N

2013-07-19

Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.

Highly efficient photocatalytic H2 evolution using TiO2 nanoparticles integrated with electrocatalytic metal phosphides as cocatalysts

NASA Astrophysics Data System (ADS)

Song, Rui; Zhou, Wu; Luo, Bing; Jing, Dengwei

2017-09-01

In this work, electrocatalysts like the metal phosphides Ni2P, NiCoP, and FeP, can serve as cocatalysts of TiO2 to form efficient composite photocatalysts for hydrogen generation from an aqueous methanol solution. On comparing Ni2P, NiCoP, and FeP and optimizing their proportions, the NiCoP(1 wt%)/TiO2 composite was found to exhibit the highest activity toward photocatalytic H2 production (1.54 μmol h-1 mg-1), which is about thirteen times that of the naked TiO2 nanoparticles. Mott-Schottky (MS) analysis indicated that the large upward shift or band bending of the Fermi energy level (EF) in metal phosphides was responsible for the enhanced activity of the composites. The steady-state photoluminescence (PL) spectra and photocurrent transient response further confirmed that the enhanced photoinduced charge transfer and band separation after TiO2 was integrated with the metal phosphides. Thus, these electrocatalysts were shown to be efficient cocatalysts that can replace noble metals as low-cost photocatalytic H2 production.

Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function

NASA Astrophysics Data System (ADS)

Adolfsson, Karl; Schneider, Martina; Hammarin, Greger; Häcker, Udo; Prinz, Christelle N.

2013-07-01

Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.

Graphitized Carbon: A Promising Stable Cathode Catalyst Support Material for Long Term PEMFC Applications.

PubMed

Mohanta, Paritosh Kumar; Regnet, Fabian; Jörissen, Ludwig

2018-05-28

Stability of cathode catalyst support material is one of the big challenges of polymer electrolyte membrane fuel cells (PEMFC) for long term applications. Traditional carbon black (CB) supports are not stable enough to prevent oxidation to CO₂ under fuel cell operating conditions. The feasibility of a graphitized carbon (GC) as a cathode catalyst support for low temperature PEMFC is investigated herein. GC and CB supported Pt electrocatalysts were prepared via an already developed polyol process. The physical characterization of the prepared catalysts was performed using transmission electron microscope (TEM), X-ray Powder Diffraction (XRD) and inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, and their electrochemical characterizations were conducted via cyclic voltammetry(CV), rotating disk electrode (RDE) and potential cycling, and eventually, the catalysts were processed using membrane electrode assemblies (MEA) for single cell performance tests. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SEM) have been used as MEA diagonostic tools. GC showed superior stability over CB in acid electrolyte under potential conditions. Single cell MEA performance of the GC-supported catalyst is comparable with the CB-supported catalyst. A correlation of MEA performance of the supported catalysts of different Brunauer⁻Emmett⁻Teller (BET) surface areas with the ionomer content was also established. GC was identified as a promising candidate for catalyst support in terms of both of the stability and the performance of fuel cell.

Hybrid bioinorganic approach to solar-to-chemical conversion.

PubMed

Nichols, Eva M; Gallagher, Joseph J; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C Y; Chang, Christopher J

2015-09-15

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥ 7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion.

Operando Spectroscopic Analysis of CoP Films Electrocatalyzing the Hydrogen-Evolution Reaction

DOE PAGES

Saadi, Fadl H.; Carim, Azhar I.; Drisdell, Walter S.; ...

2017-08-28

Transition metal phosphides exhibit high catalytic activity toward the electrochemical hydrogen-evolution reaction (HER) and resist chemical corrosion in acidic solutions. For example, an electrodeposited CoP catalyst exhibited an overpotential, η of -η < 100 mV at a current density of -10 mA cm -2 in 0.500 M H 2SO 4 (aq). To obtain a chemical description of the material as-prepared and also while effecting the HER in acidic media, such electrocatalyst films were investigated using Raman spectroscopy and X-ray absorption spectroscopy both ex situ as well as under in situ and operando conditions in 0.500 M H 2SO 4 (aq).more » Ex situ analysis using the tandem spectroscopies indicated the presence of multiple ordered and disordered phases that contained both near-zerovalent and oxidized Co species, in addition to reduced and oxygenated P species. Lastly, operando analysis indicated that the active electrocatalyst was primarily amorphous and predominantly consisted of near-zerovalent Co as well as reduced P.« less

Hybrid bioinorganic approach to solar-to-chemical conversion

PubMed Central

Nichols, Eva M.; Gallagher, Joseph J.; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C. Y.; Chang, Christopher J.

2015-01-01

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion. PMID:26305947

Biobased alkylphenols from lignins via a two-step pyrolysis - Hydrodeoxygenation approach.

PubMed

de Wild, P J; Huijgen, W J J; Kloekhorst, A; Chowdari, R K; Heeres, H J

2017-04-01

Five technical lignins (three organosolv, Kraft and soda lignin) were depolymerised to produce monomeric biobased aromatics, particularly alkylphenols, by a new two-stage thermochemical approach consisting of dedicated pyrolysis followed by catalytic hydrodeoxygenation (HDO) of the resulting pyrolysis oils. Pyrolysis yielded a mixture of guaiacols, catechols and, optionally, syringols in addition to alkylphenols. HDO with heterogeneous catalysts (Ru/C, CoMo/alumina, phosphided NiMO/C) effectively directed the product mixture towards alkylphenols by, among others, demethoxylation. Up to 15wt% monomeric aromatics of which 11wt% alkylphenols was obtained (on the lignin intake) with limited solid formation (<3wt% on lignin oil intake). For comparison, solid Kraft lignin was also directly hydrotreated for simultaneous depolymerisation and deoxygenation resulting in two times more alkylphenols. However, the alkylphenols concentration in the product oil is higher for the two-stage approach. Future research should compare direct hydrotreatment and the two-stage approach in more detail by techno-economic assessments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver doped catalysts for treatment of exhaust

DOEpatents

Park, Paul Worn; Hester, Virgil Raymond; Ragle, Christie Susan; Boyer, Carrie L.

2009-06-02

A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

Supported phosphate and carbonate salts for heterogeneous catalysis of triglycerides to fatty acid methyl esters

NASA Astrophysics Data System (ADS)

Britton, Stephanie Lynne

Fatty acid methyl esters made from vegetable oil, or biodiesel, have been identified as a substitute for diesel derived from crude oil. Biodiesel is currently made using a homogeneous base catalyst to perform the transesterification of triglycerides with methanol to generate fatty acid methyl esters (FAME). The use of a homogeneous catalyst necessitates additional purification of the product and byproducts before sale, and the catalyst is consumed and discarded. The development of a heterogeneous basic catalyst for the production of FAME is desirable. Tribasic phosphate salts and dibasic carbonate salts are active for the production of FAME but generally operate as homogeneous catalysts. Supporting these phosphate and carbonate salts on mesoporous MCM-41, microporous silica gel, and nonporous a-alumina proved successful to greater or lesser degrees depending on the identity of the support and pretreatment of the support. Although these salts were supported and were active for the production of FAME from canola oil, they proved to be operating as homogeneous catalysts due to leaching of the active species off the surface of the support. Further investigation of the active species present in the tribasic phosphate catalysts identified the active support as orthophosphate, and NMR studies revealed the phosphorus to be present as orthophosphate and diphosphate in varying proportions in each catalyst. Evaluation of the acid-washing support pretreatment process revealed that the exposure of the support to acid plays a large role in the development of activity on the surface of the catalyst, but manipulation of these parameters did not prevent leaching of the active site off the surface of the catalyst. Alternate methods of support pretreatment were no more effective in preventing leaching. Tribasic phosphate supported on silica gel is not effective as a heterogeneous catalyst for FAME production from triglycerides because of the lack of stability of the phosphate on the support. The support is not stable under the reaction conditions, and alternatives should be explored to develop a heterogeneous base catalyst for the production of FAME.

Activity and Stability of Dispersed Multi Metallic Pt-based Catalysts for CO Tolerance in Proton Exchange Membrane Fuel Cell Anodes.

PubMed

Hassan, Ayaz; Ticianelli, Edson A

2018-01-01

Studies aiming at improving the activity and stability of dispersed W and Mo containing Pt catalysts for the CO tolerance in proton exchange membrane fuel cell (PEMFC) anodes are revised for the following catalyst systems: (1) a carbon supported PtMo electrocatalyst submitted to heat treatments; (2) Pt and PtMo nanoparticles deposited on carbon-supported molybdenum carbides (Mo2C/C); (3) ternary and quaternary materials formed by PtMoFe/C, PtMoRu/C and PtMoRuFe/C and; (4) Pt nanoparticles supported on tungsten carbide/carbon catalysts and its parallel evaluation with carbon supported PtW catalyst. The heat-treated (600 oC) Pt-Mo/C catalyst showed higher hydrogen oxidation activity in the absence and in the presence of CO and better stability, compared to all other Mo-containing catalysts. PtMoRuFe, PtMoFe, PtMoRu supported on carbon and Pt supported on Mo2C/C exhibited similar CO tolerances but better stability, as compared to as-prepared PtMo supported on carbon. Among the tungsten-based catalysts, tungsten carbide supported Pt catalyst showed reasonable performance and reliable stability in comparison to simple carbon supported PtW catalyst, though an uneven level of catalytic activity towards H2 oxidation in presence of CO is observed for the former as compared to Mo containing catalyst. However, a small dissolution of Mo, Ru, Fe and W from the anodes and their migration toward cathodes during the cell operation is observed. These results indicate that the fuel cell performance and stability has been improved but not yet totally resolved.

Graphene-Supported Platinum Catalyst-Based Membrane Electrode Assembly for PEM Fuel Cell

NASA Astrophysics Data System (ADS)

Devrim, Yilser; Albostan, Ayhan

2016-08-01

The aim of this study is the preparation and characterization of a graphene-supported platinum (Pt) catalyst for proton exchange membrane fuel cell (PEMFC) applications. The graphene-supported Pt catalysts were prepared by chemical reduction of graphene and chloroplatinic acid (H2PtCl6) in ethylene glycol. X-ray powder diffraction, thermogravimetric analysis (TGA) and scanning electron microscopy have been used to analyze structure and surface morphology of the graphene-supported catalyst. The TGA results showed that the Pt loading of the graphene-supported catalyst was 31%. The proof of the Pt particles on the support surfaces was also verified by energy-dispersive x-ray spectroscopy analysis. The commercial carbon-supported catalyst and prepared Pt/graphene catalysts were used as both anode and cathode electrodes for PEMFC at ambient pressure and 70°C. The maximum power density was obtained for the Pt/graphene-based membrane electrode assembly (MEA) with H2/O2 reactant gases as 0.925 W cm2. The maximum current density of the Pt/graphene-based MEA can reach 1.267 and 0.43 A/cm2 at 0.6 V with H2/O2 and H2/air, respectively. The MEA prepared by the Pt/graphene catalyst shows good stability in long-term PEMFC durability tests. The PEMFC cell voltage was maintained at 0.6 V without apparent voltage drop when operated at 0.43 A/cm2 constant current density and 70°C for 400 h. As a result, PEMFC performance was found to be superlative for the graphene-supported Pt catalyst compared with the Pt/C commercial catalyst. The results indicate the graphene-supported Pt catalyst could be utilized as the electrocatalyst for PEMFC applications.

Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF₂-MgO Carriers.

PubMed

Bonarowska, Magdalena; Wojciechowska, Maria; Zieliński, Maciej; Kiderys, Angelika; Zieliński, Michał; Winiarek, Piotr; Karpiński, Zbigniew

2016-11-25

Pd/MgO, Pd/MgF₂ and Pd/MgO-MgF₂ catalysts were investigated in the reaction of CCl₄ hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF₂-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C₂-C₅ hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF₂ is beneficial for shaping high activity of palladium catalysts. The MgO-MgF₂ support characterized by stronger Lewis acidity than MgF₂ contributes to very good catalytic activity for a relatively long reaction period (~5 h) but subsequent neutralization of stronger acid centers (by coking) eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO) are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

Gap/silicon Tandem Solar Cell with Extended Temperature Range

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A. (Inventor)

2006-01-01

A two-junction solar cell has a bottom solar cell junction of crystalline silicon, and a top solar cell junction of gallium phosphide. A three (or more) junction solar cell has bottom solar cell junctions of silicon, and a top solar cell junction of gallium phosphide. The resulting solar cells exhibit improved extended temperature operation.

Attrition resistant Fischer-Tropsch catalyst and support

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2004-05-25

A catalyst support having improved attrition resistance and a catalyst produced therefrom. The catalyst support is produced by a method comprising the step of treating calcined .gamma.-alumina having no catalytic material added thereto with an acidic aqueous solution having an acidity level effective for increasing the attrition resistance of the calcined .gamma.-alumina.

Synthesis, characterization, and catalytic activity in Suzuki coupling and catalase-like reactions of new chitosan supported Pd catalyst.

PubMed

Baran, Talat; Inanan, Tülden; Menteş, Ayfer

2016-07-10

The aim of this study is to analyze the synthesis of a new chitosan supported Pd catalyst and examination of its catalytic activity in: Pd catalyst was synthesized using chitosan as a biomaterial and characterized with FTIR, TG/DTG, XRD, (1)H NMR, (13)C NMR, SEM-EDAX, ICP-OES, Uv-vis spectroscopies, and magnetic moment, along with molar conductivity analysis. Biomaterial supported Pd catalyst indicated high activity and long life time as well as excellent turnover number (TON) and turnover frequency (TOF) values in Suzuki reaction. Biomaterial supported Pd catalyst catalyzed H2O2 decomposition reaction with considerable high activity using comparatively small loading catalyst (10mg). Redox potential of biomaterial supported Pd catalyst was still high without negligible loss (13% decrease) after 10 cycles in reusability tests. As a consequence, eco-friendly biomaterial supported Pd catalyst has superior properties such as high thermal stability, long life time, easy removal from reaction mixture and durability to air, moisture and high temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Zircon Supported Copper Catalysts for the Steam Reforming of Methanol

NASA Astrophysics Data System (ADS)

Widiastri, M.; Fendy, Marsih, I. N.

2008-03-01

Steam reforming of methanol (SRM) is known as one of the most favorable catalytic processes for producing hydrogen. Current research on zirconia, ZrO2 supported copper catalyst revealed that CuO/ZrO2 as an active catalyst for the SRM. Zircon, ZrSiO4 is available from the by-product of tin mining. In the work presented here, the catalytic properties of CuO/ZrSiO4 with various copper oxide compositions ranging from 2.70% (catalyst I), 4.12% (catalyst II), and 7.12%-mass (catalyst III), synthesized by an incipient wetness impregnation technique, were investigated to methanol conversion, selectivity towards CO formation, and effect of ZnO addition (7.83%CuO/8.01%ZnO/ZrSiO4 = catalyst V). The catalytic activity was obtained using a fixed bed reactor and the zircon supported catalyst activity was compared to those of CuO/ZnO/Al2O3 catalyst (catalyst IV) and commercial Kujang LTSC catalyst. An X-ray powder diffraction (XRD) analysis was done to identify the abundant phases of the catalysts. The catalysts topography and particle diameter were measured with scanning electron microscopy (SEM) and composition of the catalysts was measured by SEM-EDX, scanning electron microscope-energy dispersive using X-ray analysis. The results of this research provide information on the possibility of using zircon (ZrSiO4) as solid support for SRM catalysts.

Oxidation catalysts on alkaline earth supports

DOEpatents

Mohajeri, Nahid

2017-03-21

An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports

PubMed Central

Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H.

2013-01-01

Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/AlS.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/AlS.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/AlS.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size. PMID:28809270

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

PubMed

Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

2013-05-30

Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/Al S.G. ) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/Al S.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/Al S.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalysts supported on cationic surfactant-templated mesoporous aluminas

NASA Astrophysics Data System (ADS)

Seo, Jeong Gil; Youn, Min Hye; Park, Sunyoung; Jung, Ji Chul; Kim, Pil; Chung, Jin Suk; Song, In Kyu

Two types of mesoporous γ-aluminas (denoted as A-A and A-S) are prepared by a hydrothermal method under different basic conditions using cationic surfactant (cetyltrimethylammonium bromide, CTAB) as a templating agent. A-A and A-S are synthesized in a medium of ammonia solution and sodium hydroxide solution, respectively. Ni/γ-Al 2O 3 catalysts (Ni/A-A and Ni/A-S) are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of a mesoporous γ-Al 2O 3 support on the catalytic performance of Ni/γ-Al 2O 3 is investigated. The identity of basic solution strongly affects the physical properties of the A-A and A-S supports. The high surface-area of the mesoporous γ-aluminas and the strong metal-support interaction of supported catalysts greatly enhance the dispersion of nickel species on the catalyst surface. The well-developed mesopores of the Ni/A-A and Ni/A-S catalysts prohibit the polymerization of carbon species on the catalyst surface during the reaction. In the steam reforming of LNG, both Ni/A-A and Ni/A-S catalysts give better catalytic performance than the nickel catalyst supported on commercial γ-Al 2O 3 (Ni/A-C). In addition, the Ni/A-A catalyst is superior to the Ni/A-S catalyst. The relatively strong metal-support interaction of Ni/A-A catalyst effectively suppresses the sintering of metallic nickel and the carbon deposition in the steam reforming of LNG. The large pores of the Ni/A-A catalyst also play an important role in enhancing internal mass transfer during the reaction.

Synthesis and characterization of catalysts for the selective transformation of biomass-derived materials

NASA Astrophysics Data System (ADS)

Ghampson, Isaac Tyrone

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silica-supported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, analyzed as a three-phase system containing Cofcc, Cohcp and CoO particles. Catalyst properties were determined at three stages in catalyst history: (1) after the initial calcination step to thermally decompose the catalyst precursor into Co3O4, (2) after the hydrogen reduction step to activate the catalyst to Co and (3) after the FT reaction. From the study, it was observed that larger pore diameters supported higher turnover frequency; smaller pore diameters yielded larger mole fraction of CoO; XRD on post-reduction and post-FTS catalyst samples indicated significant changes in dispersivity after reduction. In the next section, the catalytic behaviors of unsupported, activated carbon-, alumina-, and SBA-15 mesoporous silica-supported molybdenum nitride catalysts were evaluated for the hydrodeoxygenation of guaiacol (2-methoxy phenol) at 300°C and 5 MPa. The nitride catalysts were prepared by thermal decomposition of bulk and supported ammonium heptamolybdate to form MoO 3 followed by nitridation in either flowing ammonia or a nitrogen/hydrogen mixture. The catalytic properties were strongly affected by the nitriding and purging treatment as well as the physical and chemical properties of support. The overall reaction was influenced by the crystalline phase present in the catalyst, dispersion of molybdenum nitride/oxynitride, and the porosity of the support. The hydrodeoxygenation of guaiacol followed two proposed reaction pathways: demethylation (DME) of guaiacol to form catechol, followed by dehydroxylation to form phenol; or a direct demethoxylation (DMO) to form phenol. The selectivity of the reaction was expressed in terms of the phenol/catechol ratio. Phenol was the predominant product for all the catalysts studied, except for the alumina-supported catalysts (an effect of the alumina support). The results from this thesis are encouraging for the application of Mo nitride based catalysts for hydrodeoxygenation of whole pyrolysis oil.

Different routes to methanol: Inelastic neutron scattering spectroscopy of adsorbates on supported copper catalysts

DOE PAGES

Kandemir, Timur; Friedrich, Matthias; Parker, Stewart F.; ...

2016-04-14

We have investigated methanol synthesis with model supported copper catalysts, Cu/ZnO and Cu/MgO, using CO/H 2 and CO 2/H 2 as feedstocks. Under CO/H 2 both catalysts show chemisorbed methoxy as a stable intermediate, the Cu/MgO catalyst also shows hydroxyls on the support. Under CO 2/H 2 the catalysts behave differently, in that formate is also seen on the catalyst. For the Cu/ZnO catalyst hydroxyls are present on the metal whereas for the Cu/MgO hydroxyls are found on the support. Furthermore, these results are consistent with a recently published model for methanol synthesis and highlight the key role of ZnOmore » in the process.« less

Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

DOEpatents

Zelenay, Piotr; Wu, Gang

2014-04-29

A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

Managing aluminum phosphide poisonings

PubMed Central

Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

2011-01-01

Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO4, coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management. PMID:21887030

Catalyst support structure, catalyst including the structure, reactor including a catalyst, and methods of forming same

DOEpatents

Van Norman, Staci A.; Aston, Victoria J.; Weimer, Alan W.

2017-05-09

Structures, catalysts, and reactors suitable for use for a variety of applications, including gas-to-liquid and coal-to-liquid processes and methods of forming the structures, catalysts, and reactors are disclosed. The catalyst material can be deposited onto an inner wall of a microtubular reactor and/or onto porous tungsten support structures using atomic layer deposition techniques.

Supported catalyst systems and method of making biodiesel products using such catalysts

DOEpatents

Kim, Manhoe; Yan, Shuli; Salley, Steven O.; Ng, K. Y. Simon

2015-10-20

A heterogeneous catalyst system, a method of preparing the catalyst system and a method of forming a biodiesel product via transesterification reactions using the catalyst system is disclosed. The catalyst system according to one aspect of the present disclosure represents a class of supported mixed metal oxides that include at least calcium oxide and another metal oxide deposited on a lanthanum oxide or cerium oxide support. Preferably, the catalysts include CaO--CeO.sub.2ZLa.sub.2O.sub.3 or CaO--La.sub.2O.sub.3/CeO.sub.2. Optionally, the catalyst may further include additional metal oxides, such as CaO--La.sub.2O.sub.3--GdOxZLa.sub.2O.sub.3.

Hierarchical nanostructured hollow spherical carbon with mesoporous shell as a unique cathode catalyst support in proton exchange membrane fuel cell.

PubMed

Fang, Baizeng; Kim, Jung Ho; Kim, Minsik; Kim, Minwoo; Yu, Jong-Sung

2009-03-07

Hierarchical nanostructured spherical carbon with hollow macroporous core in combination with mesoporous shell has been explored to support Pt cathode catalyst with high metal loading in proton exchange membrane fuel cell (PEMFC). The hollow core-mesoporous shell carbon (HCMSC) has unique structural characteristics such as large specific surface area and mesoporous volume, ensuring uniform dispersion of the supported high loading (60 wt%) Pt nanoparticles with small particle size, and well-developed three-dimensionally interconnected hierarchical porosity network, facilitating fast mass transport. The HCMSC-supported Pt(60 wt%) cathode catalyst has demonstrated markedly enhanced catalytic activity toward oxygen reduction and greatly improved PEMFC polarization performance compared with carbon black Vulcan XC-72 (VC)-supported ones. Furthermore, the HCMSC-supported Pt(40 wt%) or Pt(60 wt%) outperforms the HCMSC-supported Pt(20 wt%) even at a low catalyst loading of 0.2 mg Pt cm(-2) in the cathode, which is completely different from the VC-supported Pt catalysts. The capability of supporting high loading Pt is supposed to accelerate the commercialization of PEMFC due to the anticipated significant reduction in the amount of catalyst support required, diffusion layer thickness and fabricating cost of the supported Pt catalyst electrode.

Long life hydrocarbon conversion catalyst and method of making

DOEpatents

Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

2002-11-12

The present invention includes a catalyst that has at least four layers, (1) porous support, (2) buffer layer, (3) interfacial layer, and optionally (4) catalyst layer. The buffer layer provides a transition of thermal expansion coefficient from the porous support to the interfacial layer thereby reducing thermal expansion stress as the catalyst is heated to high operating temperatures. The method of the present invention for making the at least three layer catalyst has the steps of (1) selecting a porous support, (2) solution depositing an interfacial layer thereon, and optionally (3) depositing a catalyst material onto the interfacial layer; wherein the improvement comprises (4) depositing a buffer layer between the porous support and the interfacial layer.

Chalcogen catalysts for polymer electrolyte fuel cell

DOEpatents

Alonso-Vante, Nicolas [Buxerolles, FR; Zelenay, Piotr [Los Alamos, NM; Choi, Jong-Ho [Los Alamos, NM; Wieckowski, Andrzej [Champaign, IL; Cao, Dianxue [Urbana, IL

2009-09-15

A methanol-tolerant cathode catalyst and a membrane electrode assembly for fuel cells that includes such a cathode catalyst. The cathode catalyst includes a support having at least one transition metal in elemental form and a chalcogen disposed on the support. Methods of making the cathode catalyst and membrane electrode assembly are also described.

Chalcogen catalysts for polymer electrolyte fuel cell

DOEpatents

Zelenay, Piotr; Choi, Jong-Ho; Alonso-Vante, Nicolas; Wieckowski, Andrzej; Cao, Dianxue

2010-08-24

A methanol-tolerant cathode catalyst and a membrane electrode assembly for fuel cells that includes such a cathode catalyst. The cathode catalyst includes a support having at least one transition metal in elemental form and a chalcogen disposed on the support. Methods of making the cathode catalyst and membrane electrode assembly are also described.

Supported molten-metal catalysts

DOEpatents

Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

2001-01-01

An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

Catalyst and process for converting synthesis gas to liquid motor fuels

DOEpatents

Coughlin, Peter K.

1987-01-01

The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

Catalyst for converting synthesis gas to liquid motor fuels

DOEpatents

Coughlin, Peter K.

1986-01-01

The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

Wavelength-scale Microlasers based on VCSEL-Photonic Crystal Architecture

DTIC Science & Technology

2015-01-20

molecular beam epitaxy , MBE). We will also assume the triangular lattice of air...Abbreviations, and Acronyms InP: indium phosphide InGaAsP: indium gallium arsenide phosphide MBE: molecular beam epiitaxy VCSEL : vertical cavity...substrates and were grown by MBE. Electron beam lithography and reactive ion etching was used to deep‐etch the holes of the PhC‐ VCSELS ,

Orientation of Zn3P2 films via phosphidation of Zn precursors

NASA Astrophysics Data System (ADS)

Katsube, Ryoji; Nose, Yoshitaro

2017-02-01

Orientation of solar absorber is an important factor to achieve high efficiency of thin film solar cells. In the case of Zn3P2 which is a promising absorber of low-cost and high-efficiency solar cells, (110)/(001) orientation was only reported in previous studies. We have successfully prepared (101)-oriented Zn3P2 films by phosphidation of (0001)-oriented Zn films at 350 °C. The phosphidation mechanism of Zn is discussed through STEM observations on the partially-reacted sample and the consideration of the relationship between the crystal structures of Zn and Zn3P2 . We revealed that (0001)-oriented Zn led to nucleation of (101)-oriented Zn3P2 due to the similarity in atomic arrangement between Zn and Zn3P2 . The electrical resistivity of the (101)-oriented Zn3P2 film was lower than those of (110)/(001)-oriented films, which is an advantage of the phosphidation technique to the growth processes in previous works. The results in this study demonstrated that well-conductive Zn3P2 films could be obtained by controlling orientations of crystal grains, and provide a guiding principle for microstructure control in absorber materials.

Reducible oxide based catalysts

DOEpatents

Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

2010-04-06

A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

Graphitic Carbon Nitride Supported Catalysts for Polymer Electrolyte Fuel Cells

PubMed Central

2014-01-01

Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li+Cl–), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion testing, all graphitic carbon nitride materials are found to be more electrochemically stable compared to conventional carbon black (Vulcan XC-72R) with B-gCNM support showing the best stability. For the supported catalysts, Pt/PTI-Li+Cl– catalyst exhibits better durability with only 19% electrochemical surface area (ECSA) loss versus 36% for Pt/Vulcan after 2000 scans. Superior methanol oxidation activity is observed for all graphitic carbon nitride supported Pt catalysts on the basis of the catalyst ECSA. PMID:24748912

Two Catalysts for Selective Oxidation of Contaminant Gases

NASA Technical Reports Server (NTRS)

Wright, John D.

2011-01-01

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia. The first catalyst is of the supported-precious-metal type. This catalyst is highly active for the oxidation of halocarbons, hydrocarbons, and oxygenates at low concentrations in air. This catalyst is more active for the oxidation of hydrocarbons and halocarbons than are competing catalysts developed in recent years. This catalyst completely converts these airborne contaminant gases to carbon dioxide, water, and mineral acids that can be easily removed from the air, and does not make any chlorine gas in the process. The catalyst is thermally stable and is not poisoned by chlorine or fluorine atoms produced on its surface during the destruction of a halocarbon. In addition, the catalyst can selectively oxidize ammonia to nitrogen at a temperature between 200 and 260 C, without making nitrogen oxides, which are toxic. The temperature of 260 C is higher than the operational temperature of any other precious-metal catalyst that can selectively oxidize ammonia. The purpose of the platinum in this catalyst is to oxidize hydrocarbons and to ensure that the oxidation of halocarbons goes to completion. However, the platinum exhibits little or no activity for initiating the destruction of halocarbons. Instead, the attack on the halocarbons is initiated by the support. The support also provides a high surface area for exposure of the platinum. Moreover, the support resists deactivation or destruction by halogens released during the destruction of halocarbons. The second catalyst is of the supported- metal-oxide type. This catalyst can selectively oxidize ammonia to nitrogen at temperatures up to 400 C, without producing nitrogen oxides. This catalyst converts ammonia completely to nitrogen, even when the concentration of ammonia is very low. No other catalyst is known to oxidize ammonia selectively at such a high temperature and low concentration. Both the metal oxide and the support contribute to the activity and selectivity of this catalyst.

Isoelectronic Traps in Gallium Phosphide

NASA Astrophysics Data System (ADS)

Christian, Theresa; Alberi, Kirstin; Beaton, Daniel; Fluegel, Brian; Mascarenhas, Angelo

2015-03-01

Isoelectronic substitutional dopants can result in strongly localized exciton traps within a host bandstructure such as gallium arsenide (GaAs) or gallium phosphide (GaP). These traps have received great attention for their role in the anomalous bandgap bowing of nitrogen or bismuth-doped GaAs, creating the dramatic bandgap tunability of these unusual dilute alloys. In the wider, indirect-bandgap host material GaP, these same isoelectronic dopants create bound states within the gap that can have very high radiative efficiency and a wealth of discrete spectral transitions illuminating the symmetry of the localized excitonic trap state. We will present a comparative study of nitrogen and bismuth isoelectronic traps in GaP. Research was supported by the U. S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC36-08GO28308 and by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under contract no. DE-AC05-06OR23100.

Synthesis and characterization of supported polysugar-stabilized palladium nanoparticle catalysts for enhanced hydrodechlorination of trichloroethylene

NASA Astrophysics Data System (ADS)

Bacik, Deborah B.; Zhang, Man; Zhao, Dongye; Roberts, Christopher B.; Seehra, Mohinar S.; Singh, Vivek; Shah, Naresh

2012-07-01

Palladium (Pd) nanoparticle catalysts were successfully synthesized within an aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping ligand which offers a green alternative to conventional nanoparticle synthesis techniques. The CMC-stabilized Pd nanoparticles were subsequently dispersed within support materials using the incipient wetness impregnation technique for utilization in heterogeneous catalyst systems. The unsupported and supported (both calcined and uncalcined) Pd nanoparticle catalysts were characterized using transmission electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction, and Brunauer-Emmett-Teller surface area measurement and their catalytic activity toward the hydrodechlorination of trichloroethylene (TCE) in aqueous media was examined using homogeneous and heterogeneous catalyst systems, respectively. The unsupported Pd nanoparticles showed considerable activity toward the degradation of TCE, as demonstrated by the reaction kinetics. Although the supported Pd nanoparticle catalysts had a lower catalytic activity than the unsupported particles that were homogeneously dispersed in the aqueous solutions, the supported catalysts retained sufficient activity toward the degradation of TCE. In addition, the use of the hydrophilic Al2O3 support material induced a mass transfer resistance to TCE that affected the initial hydrodechlorination rate. This paper demonstrates that supported Pd catalysts can be applied to the heterogeneous catalytic hydrodechlorination of TCE.

Gallium-rich Pd-Ga phases as supported liquid metal catalysts

NASA Astrophysics Data System (ADS)

Taccardi, N.; Grabau, M.; Debuschewitz, J.; Distaso, M.; Brandl, M.; Hock, R.; Maier, F.; Papp, C.; Erhard, J.; Neiss, C.; Peukert, W.; Görling, A.; Steinrück, H.-P.; Wasserscheid, P.

2017-09-01

A strategy to develop improved catalysts is to create systems that merge the advantages of heterogeneous and molecular catalysis. One such system involves supported liquid-phase catalysts, which feature a molecularly defined, catalytically active liquid film/droplet layer adsorbed on a porous solid support. In the past decade, this concept has also been extended to supported ionic liquid-phase catalysts. Here we develop this idea further and describe supported catalytically active liquid metal solutions (SCALMS). We report a liquid mixture of gallium and palladium deposited on porous glass that forms an active catalyst for alkane dehydrogenation that is resistant to coke formation and is thus highly stable. X-ray diffraction and X-ray photoelectron spectroscopy, supported by theoretical calculations, confirm the liquid state of the catalytic phase under the reaction conditions. Unlike traditional heterogeneous catalysts, the supported liquid metal reported here is highly dynamic and catalysis does not proceed at the surface of the metal nanoparticles, but presumably at homogeneously distributed metal atoms at the surface of a liquid metallic phase.

An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh 2P

DOE PAGES

Griffin, Michael B.; Baddour, Frederick G.; Habas, Susan E.; ...

2017-06-06

Here, the production of hydrocarbon fuels from biomass pyrolysis requires the development of effective deoxygenation catalysts, and insight into how the properties of the support influence performance is critical for catalyst design. In this report, nanoparticles of Ni and Rh 2P were synthesized using solution-phase techniques and dispersed on high surface area supports. The supports included a relatively inert material (C), an acidic reducible metal-oxide (TiO 2), an acidic irreducible metal-oxide (Al 2O 3), and a basic irreducible metal-oxide (MgO). The eight active phase/support combinations were investigated for the deoxygenation of guaiacol, a pyrolysis vapor model compound, under ex situmore » catalytic fast pyrolysis conditions (350 °C, 0.44 MPa H 2). Compared to the baseline performance of the C-supported catalysts, Ni/TiO 2 and Rh 2P/TiO 2 exhibited higher guaiacol conversion and lower O : C ratios for C 5+ products, highlighting the enhanced activity and greater selectivity to deoxygenated products derived from the use of an acidic reducible metal-oxide support. The Al 2O 3-supported catalysts also exhibited higher conversion than the C-supported catalysts and promoted alkylation reactions, which improve carbon efficiency and increase the carbon number of the C 5+ products. However, Ni/Al 2O 3 and Rh 2P/Al 2O 3 were less selective towards deoxygenated products than the C-supported catalysts. The MgO-supported catalyst exhibited lower conversion and decreased yield of deoxygenated products compared to the C-supported catalysts. The results reported here suggest that basic metal-oxide supports may inhibit deoxygenation of phenolics under CFP conditions. Contrastingly, support acidity and reducibility were demonstrated to promote conversion and selectivity to deoxygenated products, respectively.« less

The role of support morphology on the performance of Cu/ZnO-catalyst for hydrogenation of CO{sub 2} to methanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasfy, Sara Faiz Hanna, E-mail: miss25208@gmail.com; Zabidi, Noor Asmawati Mohd, E-mail: noorasmawati-mzabidi@petronas.com.my; Shaharun, Maizatul Shima, E-mail: maizats@petronas.com.my

The effects of SBA-15 support morphology on the activity of Cu/ZnO catalyst in the hydrogenation of CO{sub 2} to methanol was investigated. In the hydrogenation of CO{sub 2} to methanol at 210°C, 2.25 MPa, H{sub 2}/CO{sub 2} ratio of three remarkable difference was obtained using Cu/ZnO catalyst supported on SBA-15 with different morphology. The catalysts were characterized using N{sub 2}-adsorption, field emission scanning microscopy (FESEM/EDX), transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR). Characterization of the catalyst showed that support morphology, surface area, metals dispersion, and reducibility influenced the catalytic performance. On the fiber-shaped SBA-15, copper dispersion was 29 % whereasmore » on the spherical-shaped SBA-15, the dispersion was 20 %. The experimental results showed that the catalyst supported over fiber-shaped SBA-15 exhibit higher CO{sub 2} conversion (13.96 %) and methanol selectivity (91.32 %) compare to catalyst supported over spherical-shaped SBA-15.« less

Novel nano-semiconductor film layer supported nano-Pd Complex Nanostructured Catalyst Pd/Ⓕ-MeOx/AC for High Efficient Selective Hydrogenation of Phenol to Cyclohexanone.

PubMed

Si, Jiaqi; Ouyang, Wenbing; Zhang, Yanji; Xu, Wentao; Zhou, Jicheng

2017-04-28

Supported metal as a type of heterogeneous catalysts are the most widely used in industrial processes. High dispersion of the metal particles of supported catalyst is a key factor in determining the performance of such catalysts. Here we report a novel catalyst Pd/Ⓕ-MeO x /AC with complex nanostructured, Pd nanoparticles supported on the platelike nano-semiconductor film/activated carbon, prepared by the photocatalytic reduction method, which exhibited high efficient catalytic performance for selective hydrogenation of phenol to cyclohexanone. Conversion of phenol achieved up to more than 99% with a lower mole ratio (0.5%) of active components Pd and phenol within 2 h at 70 °C. The synergistic effect of metal nanoparticles and nano-semiconductors support layer and the greatly increasing of contact interface of nano-metal-semiconductors may be responsible for the high efficiency. This work provides a clear demonstration that complex nanostructured catalysts with nano-metal and nano-semiconductor film layer supported on high specific surface AC can yield enhanced catalytic activity and can afford promising approach for developing new supported catalyst.

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst.

PubMed

Altava, Belén; Burguete, M Isabel; García-Verdugo, Eduardo; Luis, Santiago V

2018-04-23

Positive effects of the polymeric support on the performance of supported chiral catalysts, in terms of activity, stability and selectivity-enantioselectivity, have been reported when the support is properly selected and optimized opening the way to the design of more efficient catalytic systems.

Methane Conversion to Ethylene and Aromatics on PtSn Catalysts

DOE PAGES

Gerceker, Duygu; Motagamwala, Ali Hussain; Rivera-Dones, Keishla R.; ...

2017-02-03

Pt and PtSn catalysts supported on SiO 2 and H-ZSM-5 were studied for methane conversion under nonoxidative conditions. Addition of Sn to Pt/SiO 2 increased the turnover frequency for production of ethylene by a factor of 3, and pretreatment of the catalyst at 1123 K reduced the extent of coke formation. Pt and PtSn catalysts supported on H-ZSM-5 zeolite were prepared to improve the activity and selectivity to non-coke products. Ethylene formation rates were 20 times faster over a PtSn(1:3)/H-ZSM-5 catalyst with SiO 2:Al 2O 3 = 280 in comparison to those over PtSn(3:1)/SiO 2. H-ZSM-5-supported catalysts were also activemore » for the formation of aromatics, and the rates of benzene and naphthalene formation were increased by using more acidic H-ZSM-5 supports. These catalysts operate through a bifunctional mechanism, in which ethylene is first produced on highly dispersed PtSn nanoparticles and then is subsequently converted to benzene and naphthalene on Brønsted acid sites within the zeolite support. The most active and stable PtSn catalyst forms carbon products at a rate, 2.5 mmol of C/((mol of Pt) s), which is comparable to that of state-of-the-art Mo/H-ZSM-5 catalysts with same metal loading operated under similar conditions (1.8 mmol of C/((mol of Mo) s)). Scanning transmission electron microscopy measurements suggest the presence of smaller Pt nanoparticles on H-ZSM-5-supported catalysts, in comparison to SiO 2-supported catalysts, as a possible source of their high activity. As a result, a microkinetic model of methane conversion on Pt and PtSn surfaces, built using results from density functional theory calculations, predicts higher coupling rates on bimetallic and stepped surfaces, supporting the experimental observations that relate the high catalytic activity to small PtSn particles.« less

Polymer-Supported Raney Nickel Catalysts for Sustainable Reduction Reactions.

PubMed

Jiang, Haibin; Lu, Shuliang; Zhang, Xiaohong; Dai, Wei; Qiao, Jinliang

2016-06-25

Green is the future of chemistry. Catalysts with high selectivity are the key to green chemistry. Polymer-supported Raney catalysts have been found to have outstanding performance in the clean preparation of some chemicals. For example, a polyamide 6-supported Raney nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry, and eliminated the two main byproducts (isopropyl ether and methyl-iso-butylcarbinol) in the hydrogenation of acetone to isopropanol. Meanwhile, a model for how the polymer support brought about the elimination of byproducts is proposed and confirmed. In this account the preparation and applications of polymer-supported Raney catalysts along with the corresponding models will be reviewed.

The History of Current State of the Art of Propylene Polymerization Catalysts.

ERIC Educational Resources Information Center

Goodall, Brian L.

1986-01-01

Outlines the development of the modern catalysts for propylene polymerization, considering the historical background; structure of titanium chloride catalysts; first-generation catalysts; cocatalysts; second-generation catalysts; catalysts morphology; and third-generation (supported catalysts). (JN)

The Mechanism of Anaerobic (Microbial) Corrosion.

DTIC Science & Technology

1982-12-01

hydrogen sulfide reacts with hypophosphite (as well as phosphate and phosphite ) .to form, in the presence of mild steel, iron phosphide, simulating the...of phosphate and phosphite , but not hypophosphite, were observed to have become yellow in 24 hours. The yellow color disap- peared upon exposure to... product is an amorphous type of iron phosphide which can be !- detected b the formation of phos hine upon its acidification. Phosphine( in M IFO, 1473

Colloidal Nanochemistry Applied to the Discovery and Characterization of Earth-Abundant Nanoparticles as Catalysts for the Hydrogen Evolution Reaction and CO2 Photoreduction

NASA Astrophysics Data System (ADS)

McEnaney, Joshua M.

Colloidal nanosynthesis has become a powerful fundamental and practical science with increasing methodologies available for the formation of highly controllable, high surface area nanoparticles. By expanding these methodologies to targeted nanomaterials, we have been able to synthesize and characterize new catalytic nanoparticle systems, primarily for the catalysis of the hydrogen evolution reaction (HER) but also for CO2 photoreduction to carbonaceous fuels. Both of these reactions offer exciting potential routes toward a clean energy future if they can be produced and perform with enough cost efficiency. We begin with a discussion of the capabilities of colloidal nanosynthesis, followed by the intricacies of the HER and CO2 photoreduction. For the HER, replacing highly active noble metals with Earth-abundant, active, and stable materials is a major goal. The majority of this dissertation will focus on the discovery, characterization, and evaluation of new materials to satisfy this goal. For this, we will start by reporting on the synthesis and evaluation of new amorphous molybdenum phosphide and amorphous tungsten phosphide nanoparticles as HER catalysts. Each of the full HER evaluations will include linear scan voltammetry for testing the activity of each material, comparison versus a platinum standard electrode and a bare Ti foil substrate as controls, then sustained cyclic voltammetry as well as a galvanostatic hold for stability testing. We will then discuss the discovery of hollow nanospheres of FeP as an exceptionally active HER catalyst. This will be followed by the establishment of a synthetic route to colloidal transition metal silicide nanoparticles. Ni2Si, Pd2Si, and Cu3Si nanoparticles were all synthesized preliminarily tested for their ability to catalyze the HER. Next, we discuss phase control of cobalt sulfide nanomaterials and establish parameters in a non-polar synthesis to make each of three crystalline phases, and begin to compare them for the HER. After this, we will show specific colloidally controlled manipulations of TiO2truncated bipyramidal nanoparticles, including size control of Ag domains grown on TiO2and multilayered assemblies of TiO2 nanoparticles. Finally, we delve into the challenges and opportunities of CO2 photoreduction before concluding. Briefly, for CO2 reduction, activity has typically been low compared to the HER, product selectivity remains a major hurdle, and there is a lack of standardization in testing methods, though the infrastructures of first world countries are already built for carbon based fuels, and CO2 itself provides an excellent feedstock from a growing pollutant. We highlight colloidally synthesized SnO nanosheets with primarily exposed (001) facets as selective for ethanol production from CO2 and water, then directly compare CuPt alloy nanospheres against Pt nanospheres on a TiO2substrate for CO2 photoreduction to methane. Each of the chapters included will illustrate the powerful capabilities of colloidal nanosynthesis, as they can be applied to learn about and discover solutions to real world problems such as the development clean energy technologies.

Durability testing at 5 atmospheres of advanced catalysts and catalyst supports for gas turbine engine combustors

NASA Technical Reports Server (NTRS)

Olson, B. A.; Lee, H. C.; Osgerby, I. T.; Heck, R. M.; Hess, H.

1980-01-01

The durability of CATCOM catalysts and catalyst supports was experimentally demonstrated in a combustion environment under simulated gas turbine engine combustor operating conditions. A test of 1000 hours duration was completed with one catalyst using no. 2 diesel fuel and operating at catalytically-supported thermal combustion conditions. The performance of the catalyst was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. Tests were performed periodically to determine changes in catalytic activity of the catalyst core. Detailed parametric studies were also run at the beginning and end of the durability test, using no. 2 fuel oil. Initial and final emissions for the 1000 hours test respectively were: unburned hydrocarbons (C3 vppm):0, 146, carbon monoxide (vppm):30, 2420; nitrogen oxides (vppm):5.7, 5.6.

Liquid phase catalytic hydrodebromination of tetrabromobisphenol A on supported Pd catalysts

NASA Astrophysics Data System (ADS)

Wu, Ke; Zheng, Mengjia; Han, Yuxiang; Xu, Zhaoyi; Zheng, Shourong

2016-07-01

Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant and reductive debromination is an effective method for the abatement of TBBPA pollution. In this study, Pd catalysts supported on TiO2, CeO2, Al2O3 and SiO2 were prepared by the impregnation (the resulting catalyst denoted as im-Pd/support), deposition-precipitation (the resulting catalyst denoted as dp-Pd/support), and photo-deposition (the resulting catalyst denoted as pd-Pd/support) methods. The catalysts were characterized by N2 adsorption-desorption isotherm, X-ray diffraction, transmission electron microscopy, measurement of zeta potential, CO chemisorption, and X-ray photoelectron spectroscopy. The results showed that at an identical Pd loading amount (2.0 wt.%) Pd particle size in dp-Pd/TiO2 was much smaller than those in im-Pd/TiO2 and pd-Pd/TiO2. Pd particle size of the dp-Pd/TiO2 catalyst increased with Pd loading amount. Additionally, Pd particles in the dp-Pd/TiO2 catalysts were positively charged due to the strong metal-support interaction, whereas the cationization effect was gradually attenuated with the increase of Pd loading amount. For the liquid phase catalytic hydrodebromination (HDB) of TBBPA, tri-bromobisphenol A (tri-BBPA), di-bromobisphenol A (di-BBPA), and mono-bromobisphenol A (mono-BBPA) were identified as the intermediate products, indicative of a stepwise debromination process. The catalytic HDB of TBBPA followed the Langmuir-Hinshelwood model, reflecting an adsorption enhanced catalysis mechanism. At an identical Pd loading amount, the Pd catalyst supported on TiO2 exhibited a much higher catalytic activity than those on other supports. Furthermore, dp-Pd/TiO2 was found to be more active than im-Pd/TiO2 and pd-Pd/TiO2.

A comparative study of CeO2-Al2O3 support prepared with different methods and its application on MoO3/CeO2-Al2O3 catalyst for sulfur-resistant methanation

NASA Astrophysics Data System (ADS)

Jiang, Minhong; Wang, Baowei; Yao, Yuqin; Li, Zhenhua; Ma, Xinbin; Qin, Shaodong; Sun, Qi

2013-11-01

The CeO2-Al2O3 supports prepared with impregnation (IM), deposition precipitation (DP), and solution combustion (SC) methods for MoO3/CeO2-Al2O3 catalyst were investigated in the sulfur-resistant methanation. The supports and catalysts were characterized by N2-physisorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and temperature-programmed reduction (TPR). The N2-physisorption results indicated that the DP method was favorable for obtaining better textural properties. The TEM and RS results suggested that there is a CeO2 layer on the surface of the support prepared with DP method. This CeO2 layer not only prevented the interaction between MoO3 and γ-Al2O3 to form Al2(MoO4)3 species, but also improved the dispersion of MoO3 in the catalyst. Accordingly, the catalysts whose supports were prepared with DP method exhibited the best catalytic activity. The catalysts whose supports were prepared with SC method had the worst catalytic activity. This was caused by the formation of Al2(MoO4)3 and crystalline MoO3. Additionally, the CeO2 layer resulted in the instability of catalysts in reaction process. The increasing of calcination temperature of supports reduced the catalytic activity of all catalysts. The decrease extent of the catalysts whose supports were prepared with DP method was the lowest as the CeO2 layer prevented the interaction between MoO3 and γ-Al2O3.

Supported Dendrimer-Encapsulated Metal Clusters: Toward Heterogenizing Homogeneous Catalysts

DOE PAGES

Ye, Rong; Zhukhovitskiy, Aleksandr V.; Deraedt, Christophe V.; ...

2017-07-13

Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles—some without homogeneous analogues—for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimizemore » and expand the scope of their reactivity and selectivity. Ongoing efforts in our laboratories are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence, and structural uniformity, dendrimers have proven to be versatile scaffolds for the synthesis and stabilization of small nanoclusters. Then these dendrimer-encapsulated metal clusters (DEMCs) are adsorbed onto mesoporous silica. Through this method, we have achieved selective transformations that had been challenging to accomplish in a heterogeneous setting, e.g., π-bond activation and aldol reactions. Extensive investigation into the catalytic systems under reaction conditions allowed us to correlate the structural features (e.g., oxidation states) of the catalysts and their activity. Moreover, we have demonstrated that supported DEMCs are also excellent catalysts for typical heterogeneous reactions, including hydrogenation and alkane isomerization. Critically, these investigations also confirmed that the supported DEMCs are heterogeneous and stable against leaching. Catalysts optimization is achieved through the modulation of various parameters. The clusters are oxidized (e.g., with PhICl 2) or reduced (e.g., with H 2) in situ. Changing the dendrimer properties (e.g., generation, terminal functional groups) is analogous to ligand modification in homogeneous catalysts, which affect both catalytic activity and selectivity. Similarly, pore size of the support is another factor in determining product distribution. In a flow reactor, the flow rate is adjusted to control the residence time of the starting material and intermediates, and thus the final product selectivity. Our approach to heterogeneous catalysis affords various advantages: (1) the catalyst system can tap into the reactivity typical to homogeneous catalysts, which conventional heterogeneous catalysts could not achieve; (2) unlike most homogeneous catalysts with comparable performance, the heterogenized homogeneous catalysts can be recycled; (3) improved activity or selectivity compared to conventional homogeneous catalysts is possible because of uniquely heterogeneous parameters for optimization. Here in this Account, we will briefly introduce metal clusters and describe the synthesis and characterizations of supported DEMCs. We will present the catalysis studies of supported DEMCs in both the batch and flow modes. Lastly, we will summarize the current state of heterogenizing homogeneous catalysis and provide future directions for this area of research.« less

Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adeyiga, Adeyinka

2010-02-05

Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditionsmore » as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).« less

Molecular metal catalysts on supports: organometallic chemistry meets surface science.

PubMed

Serna, Pedro; Gates, Bruce C

2014-08-19

Recent advances in the synthesis and characterization of small, essentially molecular metal complexes and metal clusters on support surfaces have brought new insights to catalysis and point the way to systematic catalyst design. We summarize recent work unraveling effects of key design variables of site-isolated catalysts: the metal, metal nuclearity, support, and other ligands on the metals, also considering catalysts with separate, complementary functions on supports. The catalysts were synthesized with the goal of structural simplicity and uniformity to facilitate incisive characterization. Thus, they are essentially molecular species bonded to porous supports chosen for their high degree of uniformity; the supports are crystalline aluminosilicates (zeolites) and MgO. The catalytic species are synthesized in reactions of organometallic precursors with the support surfaces; the precursors include M(L)2(acetylacetonate)1-2, with M = Ru, Rh, Ir, or Au and the ligands L = C2H4, CO, or CH3. Os3(CO)12 and Ir4(CO)12 are used as precursors of supported metal clusters, and some such catalysts are made by ship-in-a-bottle syntheses to trap the clusters in zeolite cages. The simplicity and uniformity of the supported catalysts facilitate precise structure determinations, even in reactive atmospheres and during catalysis. The methods of characterizing catalysts in reactive atmospheres include infrared (IR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and nuclear magnetic resonance (NMR) spectroscopies, and complementary methods include density functional theory and atomic-resolution aberration-corrected scanning transmission electron microscopy for imaging of individual metal atoms. IR, NMR, XANES, and microscopy data demonstrate the high degrees of uniformity of well-prepared supported species. The characterizations determine the compositions of surface metal complexes and clusters, including the ligands and the metal-support bonding and structure, which identify the supports as ligands with electron-donor properties that influence reactivity and catalysis. Each of the catalyst design variables has been varied independently, illustrated by mononuclear and tetranuclear iridium on zeolite HY and on MgO and by isostructural rhodium and iridium (diethylene or dicarbonyl) complexes on these supports. The data provide examples resolving the roles of the catalyst design variables and place the catalysis science on a firm foundation of organometallic chemistry linked with surface science. Supported molecular catalysts offer the advantages of characterization in the absence of solvents and with surface-science methods that do not require ultrahigh vacuum. Families of supported metal complexes have been made by replacement of ligands with others from the gas phase. Spectroscopically identified catalytic reaction intermediates help to elucidate catalyst performance and guide design. The methods are illustrated for supported complexes and clusters of rhodium, iridium, osmium, and gold used to catalyze reactions of small molecules that facilitate identification of the ligands present during catalysis: alkene dimerization and hydrogenation, H-D exchange in the reaction of H2 with D2, and CO oxidation. The approach is illustrated with the discovery of a highly active and selective MgO-supported rhodium carbonyl dimer catalyst for hydrogenation of 1,3-butadiene to give butenes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerceker, Duygu; Motagamwala, Ali Hussain; Rivera-Dones, Keishla R.

Pt and PtSn catalysts supported on SiO 2 and H-ZSM-5 were studied for methane conversion under nonoxidative conditions. Addition of Sn to Pt/SiO 2 increased the turnover frequency for production of ethylene by a factor of 3, and pretreatment of the catalyst at 1123 K reduced the extent of coke formation. Pt and PtSn catalysts supported on H-ZSM-5 zeolite were prepared to improve the activity and selectivity to non-coke products. Ethylene formation rates were 20 times faster over a PtSn(1:3)/H-ZSM-5 catalyst with SiO 2:Al 2O 3 = 280 in comparison to those over PtSn(3:1)/SiO 2. H-ZSM-5-supported catalysts were also activemore » for the formation of aromatics, and the rates of benzene and naphthalene formation were increased by using more acidic H-ZSM-5 supports. These catalysts operate through a bifunctional mechanism, in which ethylene is first produced on highly dispersed PtSn nanoparticles and then is subsequently converted to benzene and naphthalene on Brønsted acid sites within the zeolite support. The most active and stable PtSn catalyst forms carbon products at a rate, 2.5 mmol of C/((mol of Pt) s), which is comparable to that of state-of-the-art Mo/H-ZSM-5 catalysts with same metal loading operated under similar conditions (1.8 mmol of C/((mol of Mo) s)). Scanning transmission electron microscopy measurements suggest the presence of smaller Pt nanoparticles on H-ZSM-5-supported catalysts, in comparison to SiO 2-supported catalysts, as a possible source of their high activity. As a result, a microkinetic model of methane conversion on Pt and PtSn surfaces, built using results from density functional theory calculations, predicts higher coupling rates on bimetallic and stepped surfaces, supporting the experimental observations that relate the high catalytic activity to small PtSn particles.« less

Fly ash zeolite catalyst support for Fischer-Tropsch synthesis

NASA Astrophysics Data System (ADS)

Campen, Adam

This dissertation research aimed at evaluating a fly ash zeolite (FAZ) catalyst support for use in heterogeneous catalytic processes. Gas phase Fischer-Tropsch Synthesis (FTS) over a fixed-bed of the prepared catalyst/FAZ support was identified as an appropriate process for evaluation, by comparison with commercial catalyst supports (silica, alumina, and 13X). Fly ash, obtained from the Wabash River Generating Station, was first characterized using XRD, SEM/EDS, particle size, and nitrogen sorption techniques. Then, a parametric study of a two-step alkali fusion/hydrothermal treatment process for converting fly ash to zeolite frameworks was performed by varying the alkali fusion agent, agent:flyash ratio, fusion temperature, fused ash/water solution, aging time, and crystallization time. The optimal conditions for each were determined to be NaOH, 1.4 g NaOH: 1 g fly ash, 550 °C, 200 g/L, 12 hours, and 48 hours. This robust process was applied to the fly ash to obtain a faujasitic zeolite structure with increased crystallinity (40 %) and surface area (434 m2/g). Following the modification of fly ash to FAZ, ion exchange of H+ for Na+ and cobalt incipient wetness impregnation were used to prepare a FTS catalyst. FTS was performed on the catalysts at 250--300 °C, 300 psi, and with a syngas ratio H2:CO = 2. The HFAZ catalyst support loaded with 11 wt% cobalt resulted in a 75 % carbon selectivity for C5 -- C18 hydrocarbons, while methane and carbon dioxide were limited to 13 and 1 %, respectively. Catalyst characterization was performed by XRD, N2 sorption, TPR, and oxygen pulse titration to provide insight to the behavior of each catalyst. Overall, the HFAZ compared well with silica and 13X supports, and far exceeded the performance of the alumina support under the tested conditions. The successful completion of this research could add value to an underutilized waste product of coal combustion, in the form of catalyst supports in heterogeneous catalytic processes.

Enhanced catalyst for converting synthesis gas to liquid motor fuels

DOEpatents

Coughlin, Peter K.

1986-01-01

The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

Method of forming supported doped palladium containing oxidation catalysts

DOEpatents

Mohajeri, Nahid

2014-04-22

A method of forming a supported oxidation catalyst includes providing a support comprising a metal oxide or a metal salt, and depositing first palladium compound particles and second precious metal group (PMG) metal particles on the support while in a liquid phase including at least one solvent to form mixed metal comprising particles on the support. The PMG metal is not palladium. The mixed metal particles on the support are separated from the liquid phase to provide the supported oxidation catalyst.

Hydrothermal performance of catalyst supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elam, Jeffrey W.; Marshall, Christopher L.; Libera, Joseph A.

A high surface area catalyst with a mesoporous support structure and a thin conformal coating over the surface of the support structure. The high surface area catalyst support is adapted for carrying out a reaction in a reaction environment where the thin conformal coating protects the support structure within the reaction environment. In various embodiments, the support structure is a mesoporous silica catalytic support and the thin conformal coating comprises a layer of metal oxide resistant to the reaction environment which may be a hydrothermal environment.

Design and application of sporopollenin microcapsule supported palladium catalyst: Remarkably high turnover frequency and reusability in catalysis of biaryls.

PubMed

Baran, Talat; Sargin, Idris; Kaya, Murat; Menteş, Ayfer; Ceter, Talip

2017-01-15

Bio-based catalyst support materials with high thermal and structural stability are desired for catalysts systems requiring harsh conditions. In this study, a thermally stable palladium catalyst (up to 440°C) was designed from sporopollenin, which occurs naturally in the outer exine layer of pollens and is widely acknowledged as chemically very stable and inert biological material. Catalyst design procedure included (1) extraction of sporopollenin microcapsules from Betula pendula pollens (∼25μm), (2) amino-functionalisation of the microcapsules, (3) Schiff base modification and (4) preparation of Pd(II) catalyst. The catalytic activity of the sporopollenin microcapsule supported palladium catalyst was tested in catalysis of biaryls by following a fast, simple and green microwave-assisted method. We recorded outstanding turnover number (TON: 40,000) and frequency (TOF: 400,000) for the catalyst in Suzuki coupling reactions. The catalyst proved to be reusable at least in eight cycles. The catalyst can be suggested for different catalyst systems due to its thermal and structural durability, reusability, inertness to air and its eco-friendly nature. Copyright © 2016 Elsevier Inc. All rights reserved.

Efficient water reduction with gallium phosphide nanowires

PubMed Central

Standing, Anthony; Assali, Simone; Gao, Lu; Verheijen, Marcel A.; van Dam, Dick; Cui, Yingchao; Notten, Peter H. L.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

2015-01-01

Photoelectrochemical hydrogen production from solar energy and water offers a clean and sustainable fuel option for the future. Planar III/V material systems have shown the highest efficiencies, but are expensive. By moving to the nanowire regime the demand on material quantity is reduced, and new materials can be uncovered, such as wurtzite gallium phosphide, featuring a direct bandgap. This is one of the few materials combining large solar light absorption and (close to) ideal band-edge positions for full water splitting. Here we report the photoelectrochemical reduction of water, on a p-type wurtzite gallium phosphide nanowire photocathode. By modifying geometry to reduce electrical resistance and enhance optical absorption, and modifying the surface with a multistep platinum deposition, high current densities and open circuit potentials were achieved. Our results demonstrate the capabilities of this material, even when used in such low quantities, as in nanowires. PMID:26183949

Autothermal and partial oxidation reformer-based fuel processor, method for improving catalyst function in autothermal and partial oxidation reformer-based processors

DOEpatents

Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon H. D.; Ahluwalia, Rajesh K.

2013-01-08

The invention provides a fuel processor comprising a linear flow structure having an upstream portion and a downstream portion; a first catalyst supported at the upstream portion; and a second catalyst supported at the downstream portion, wherein the first catalyst is in fluid communication with the second catalyst. Also provided is a method for reforming fuel, the method comprising contacting the fuel to an oxidation catalyst so as to partially oxidize the fuel and generate heat; warming incoming fuel with the heat while simultaneously warming a reforming catalyst with the heat; and reacting the partially oxidized fuel with steam using the reforming catalyst.

Stable metal–organic framework-supported niobium catalysts

DOE PAGES

Ahn, Sol; Thornburg, Nicholas E.; Li, Zhanyong; ...

2016-10-31

In this study by developing structurally well-defined, supported oxide catalysts remains a significant challenge. Here, we report the grafting of Nb(V) oxide sites onto the nodes of the Zr-based metal organic framework (MOF) NU-1000 as a stable, well-defined catalyst support. Nb(V) oxide was deposited with loadings up to 1.6 mmol/g via two post-synthetic methods: atomic layer deposition in a MOF (AIM), and solution-phase grafting in a MOF (SIM). Difference envelope density (DED) measurements indicated that the two synthetic methods resulted in different local structures of the Nb(V) ions within NU-1000. Despite their high Nb(V) loadings, which were equivalent to >60%more » surface coverage, nearly all Nb(V) sites of the MOF-supported catalysts were active sites for alkene epoxidation, as confirmed by phenylphosphonic acid titration. The MOF-supported catalysts were more selective than the control Nb-ZrO 2 catalyst for cyclohexene epoxidation with aqueous H 2O 2, and were far more active on a gravimetric basis.« less

CO 2 hydrogenation over oxide-supported PtCo catalysts: The role of the oxide support in determining the product selectivity

DOE PAGES

Kattel, Shyam; Yu, Weiting; Yang, Xiaofang; ...

2016-05-09

By simply changing the oxide support, the selectivity of a metal–oxide catalysts can be tuned. For the CO 2 hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO 2, ZrO 2, and TiO 2), replacing a TiO 2 support by CeO 2 or ZrO 2 selectively strengthens the binding of C,O-bound and O-bound species at the PtCo–oxide interface, leading to a different product selectivity. Lastly, these results reveal mechanistic insights into how the catalytic performance of metal–oxide catalysts can be fine-tuned.

Nanostructured catalyst supports

DOEpatents

Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

2012-10-02

The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

DOT National Transportation Integrated Search

1997-04-01

An experimental study of sulfur tolerant zeolite platinum catalysts for aormatics hydrogenation. Platinum catalysts supported on Y-zeolite have been prepared and characterized in various ways, including the hydrogenation of toluene in a high pressure...

Facile approach to prepare Pt decorated SWNT/graphene hybrid catalytic ink

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayavan, Sundar, E-mail: sundarmayavan@cecri.res.in; Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701; Mandalam, Aditya

Highlights: • Pt NPs were in situ synthesized onto CNT–graphene support in aqueous solution. • The as-prepared material was used directly as a catalyst ink without further treatment. • Catalyst ink is active toward methanol oxidation. • This approach realizes both scalable and greener production of hybrid catalysts. - Abstract: Platinum nanoparticles were in situ synthesized onto hybrid support involving graphene and single walled carbon nanotube in aqueous solution. We investigate the reduction of graphene oxide, and platinum nanoparticle functionalization on hybrid support by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The as-preparedmore » platinum on hybrid support was used directly as a catalyst ink without further treatment and is active toward methanol oxidation. This work realizes both scalable and greener production of highly efficient hybrid catalysts, and would be valuable for practical applications of graphene based fuel cell catalysts.« less

Crystalline titanate catalyst supports

DOEpatents

Anthony, R.G.; Dosch, R.G.

1993-01-05

A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

Crystalline titanate catalyst supports

DOEpatents

Anthony, Rayford G.; Dosch, Robert G.

1993-01-01

A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

Enhanced catalyst and process for converting synthesis gas to liquid motor fuels

DOEpatents

Coughlin, Peter K.

1986-01-01

The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Dongyan, E-mail: xdy0156@sina.com; Ma, Hong; Cheng, Fei

2014-05-01

Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidicmore » property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity.« less

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

PubMed Central

Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

2016-01-01

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF–supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected. PMID:28335275

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells.

PubMed

Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

2016-08-15

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF-supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

Predicting catalyst-support interactions between metal nanoparticles and amorphous silica supports

NASA Astrophysics Data System (ADS)

Ewing, Christopher S.; Veser, Götz; McCarthy, Joseph J.; Lambrecht, Daniel S.; Johnson, J. Karl

2016-10-01

Metal-support interactions significantly affect the stability and activity of supported catalytic nanoparticles (NPs), yet there is no simple and reliable method for estimating NP-support interactions, especially for amorphous supports. We present an approach for rapid prediction of catalyst-support interactions between Pt NPs and amorphous silica supports for NPs of various sizes and shapes. We use density functional theory calculations of 13 atom Pt clusters on model amorphous silica supports to determine linear correlations relating catalyst properties to NP-support interactions. We show that these correlations can be combined with fast discrete element method simulations to predict adhesion energy and NP net charge for NPs of larger sizes and different shapes. Furthermore, we demonstrate that this approach can be successfully transferred to Pd, Au, Ni, and Fe NPs. This approach can be used to quickly screen stability and net charge transfer and leads to a better fundamental understanding of catalyst-support interactions.

A durable PtRu/C catalyst with a thin protective layer for direct methanol fuel cells.

PubMed

Shimazaki, Yuzuru; Hayasaka, Sho; Koyama, Tsubasa; Nagao, Daisuke; Kobayashi, Yoshio; Konno, Mikio

2010-11-15

A methanol oxidation catalyst with improved durability in acidic environments is reported. The catalyst consists of PtRu alloy nanoparticles on a carbon support that were stabilized with a silane-coupling agent. The catalyst was prepared by reducing ions of Pt and Ru in the presence of a carbon support and the silane-coupling agent. The careful choice of preparatory conditions such as the concentration of the silane-coupling agent and solution pH resulted in the preparation of catalyst in which the PtRu nanoparticles were dispersively adsorbed onto the carbon support. The catalytic activity was similar to that of a commercial catalyst and was unchanged after immersion in sulfuric acid solution for 1000 h, suggesting the high durability of the PtRu catalyst for the anode of direct methanol fuel cells. Copyright © 2010 Elsevier Inc. All rights reserved.

Status of indium phosphide solar cell development at Spire

NASA Technical Reports Server (NTRS)

Spitzer, M. B.; Keavney, C. J.; Vernon, S. M.

1987-01-01

On-going development of indium phosphide solar cells for space applications is presented. The development is being carried out with a view towards both high conversion efficiency and simplicity of manufacture. The cell designs comprise the ion-implanted cell, the indium tin oxide top contact cell, and the epitaxial cell grown by metal organic chemical vapor deposition. Modelling data on the limit to the efficiency are presented and comparison is made to measured performance data.

Gallium phosphide energy converters

NASA Technical Reports Server (NTRS)

Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

1996-01-01

Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

Catalytic destruction of PCDD/Fs over vanadium oxide-based catalysts.

PubMed

Yu, Ming-Feng; Lin, Xiao-Qing; Li, Xiao-Dong; Yan, Mi; Prabowo, Bayu; Li, Wen-Wei; Chen, Tong; Yan, Jian-Hua

2016-08-01

Vanadium oxide-based catalysts were developed for the destruction of vapour phase PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans). A vapour phase PCDD/Fs generating system was designed to supply stable PCDD/Fs steam with initial concentration of 3.2 ng I-TEQ Nm(-3). Two kinds of titania (nano-TiO2 and conventional TiO2) and alumina were used as catalyst supports. For vanadium-based catalysts supported on nano-TiO2, catalyst activity is enhanced with operating temperature increasing from 160 to 300 °C and then reduces with temperature rising further to 350 °C. It is mainly due to the fact that high volatility of organic compounds at 350 °C suppresses adsorption of PCDD/Fs on catalysts surface and then further inhibits the reaction between catalyst and PCDD/Fs. The optimum loading of vanadium on nano-TiO2 support is 5 wt.% where vanadium oxide presents highly dispersed amorphous state according to the Raman spectra and XRD patterns. Excessive vanadium will block the pore space and form microcrystalline V2O5 on the support surface. At the vanadium loading of 5 wt.%, nano-TiO2-supported catalyst performs best on PCDD/Fs destruction compared to Al2O3 and conventional TiO2. Chemical states of vanadium in the fresh, used and reoxidized VOx(5 %)/TiO2 catalysts at different operating temperature are also analysed by XPS.

Support effects in single atom iron catalysts on adsorption characteristics of toxic gases (NO2, NH3, SO3 and H2S)

NASA Astrophysics Data System (ADS)

Gao, Zhengyang; Yang, Weijie; Ding, Xunlei; Lv, Gang; Yan, Weiping

2018-04-01

The effects of support on gas adsorption is crucial for single atom catalysts design and optimization. To gain insight into support effects on gas adsorption characteristics, a comprehensive theoretical study was performed to investigate the adsorption characteristics of toxic gases (NO2, NH3, SO3 and H2S) by utilizing single atom iron catalysts with three graphene-based supports. The adsorption geometry, adsorption energy, electronic and magnetic properties of the adsorption system have been explored. Additionally, the support effects have been analyzed through d-band center and Fermi softness, and thermodynamic analysis has been performed to consider the effect of temperature on gas adsorption. The support effects have a remarkable influence on the adsorption characteristics of four types of toxic gases which is determined by the electronic structure of graphene-based support, and the electronic structure can be characterized by Fermi softness of catalysts. Fermi softness and uplift height of Fe atom could be good descriptors for the adsorption activity of single atom iron catalysts with graphene-based supports. The findings can lay a foundation for the further study of graphene-based support effects in single atom catalysts and provide a guideline for development and design of new graphene-based support materials utilizing the idea of Fermi softness.

Supported organometallic catalysts for hydrogenation and Olefin Polymerization

DOEpatents

Marks, Tobin J.; Ahn, Hongsang

2001-01-01

Novel heterogeneous catalysts for the which hydrogenation of olefins and arenes with high conversion rates under ambient conditions and the polymerization of olefins have been developed. The catalysts are synthesized from Ziegler-type precatalysts by supporting them on sulfate-modified zirconia.

Textured catalysts and methods of making textured catalysts

DOEpatents

Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

2007-03-06

A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Multi-stage catalyst systems and uses thereof

DOEpatents

Ozkan, Umit S [Worthington, OH; Holmgreen, Erik M [Columbus, OH; Yung, Matthew M [Columbus, OH

2009-02-10

Catalyst systems and methods provide benefits in reducing the content of nitrogen oxides in a gaseous stream containing nitric oxide (NO), hydrocarbons, carbon monoxide (CO), and oxygen (O.sub.2). The catalyst system comprises an oxidation catalyst comprising a first metal supported on a first inorganic oxide for catalyzing the oxidation of NO to nitrogen dioxide (NO.sub.2), and a reduction catalyst comprising a second metal supported on a second inorganic oxide for catalyzing the reduction of NO.sub.2 to nitrogen (N.sub.2).

Selective Oxidation of n-Hexane by Cu (II) Nanoclusters Supported on Nanocrystalline Zirconia Catalyst.

PubMed

Acharyya, Shankha Shubhra; Ghosh, Shilpi; Adak, Shubhadeep; Singh, Raghuvir; Saran, Sandeep; Bal, Rajaram

2015-08-01

Cu (II) nanoclusters supported on nanocrystalline zirconia catalyst (with size ~15 nm), was prepared by using cationic surfactant cetyltrimethylammonium in a hydrothermal synthesis method. The catalyst was characterized by XRD, XPS, TGA, SEM, TEM, FTIR and ICP-AES. The catalyst was found to be efficient in selective oxidation of n-hexane to 2-hexanol. An n-hexane conversion of 55%, with a 2-hexanol selectivity of 70% was achieved over this catalyst in liquid phase, without the use of any solvent. The catalyst can be reused several times without any significant activity loss.

A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

NASA Astrophysics Data System (ADS)

Rodríguez, Julia L.; Valenzuela, Miguel A.; Tiznado, Hugo; Poznyak, Tatiana; Chairez, Isaac; Magallanes, Diana

2017-02-01

The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH)2, NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

Pt based PEMFC catalysts prepared from colloidal particle suspensions--a toolbox for model studies.

PubMed

Speder, Jozsef; Altmann, Lena; Roefzaad, Melanie; Bäumer, Marcus; Kirkensgaard, Jacob J K; Mortensen, Kell; Arenz, Matthias

2013-03-14

A colloidal synthesis approach is presented that allows systematic studies of the properties of supported proton exchange membrane fuel cell (PEMFC) catalysts. The applied synthesis route is based on the preparation of monodisperse nanoparticles in the absence of strong binding organic stabilizing agents. No temperature post-treatment of the catalyst is required rendering the synthesis route ideally suitable for comparative studies. We report work concerning a series of catalysts based on the same colloidal Pt nanoparticle (NP) suspension, but with different high surface area (HSA) carbon supports. It is shown that for the prepared catalysts the carbon support has no catalytic co-function, but carbon pre-treatment leads to enhanced sticking of the Pt NPs on the support. An unwanted side effect, however, is NP agglomeration during synthesis. By contrast, enhanced NP sticking without agglomeration can be accomplished by the addition of an ionomer to the NP suspension. The catalytic activity of the prepared catalysts for the oxygen reduction reaction is comparable to industrial catalysts and no influence of the particle size is found in the range of 2-5 nm.

Development of Ultra-Low Platinum Alloy Cathode Catalysts for PEM Fuel Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popov, Branko N.; Weidner, John

2016-01-07

The goal of this project is to synthesize a low cost PEM fuel cell cathode catalyst and support with optimized average mass activity, stability of mass activity, initial high current density performance under H 2/air (power density), and catalyst and support stability able to meet 2017 DOE targets for electrocatalysts for transportation applications. Pt*/ACCS-2 catalyst was synthesized according to a novel methodology developed at USC through: (i) surface modification, (ii) metal catalyzed pyrolysis and (iii) chemical leaching to remove excess meal used to dope the support. Pt* stands for suppressed platinum catalyst synthesized with Co doped platinum. The procedure resultsmore » in increasing carbon graphitization, inclusion of cobalt in the bulk and formation of non-metallic active sites on the carbon surface. Catalytic activity of the support shows an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass transfer regions and 2.5% H 2O 2 production. Pt*/ACCS-2 catalyst durability under 0.6-1.0 V potential cycling and support stability under 1.0-1.5 V potential cycling was evaluated. The results indicated excellent catalyst and support performance under simulated start-up/shut down operating conditions (1.0 – 1.5 V, 5000 cycles) which satisfy DOE 2017 catalyst and support durability and activity. The 30% Pt*/ACCS-2 catalyst showed high initial mass activity of 0.34 A/mg PGM at 0.9 ViR-free and loss of mass activity of 45% after 30,000 cycles (0.6-1.0 V). The catalyst performance under H 2-air fuel cell operating conditions showed only 24 mV (iR-free) loss at 0.8 A/cm 2 with an ECSA loss of 42% after 30,000 cycles (0.6-1.0 V). The support stability under 1.0-1.5 V potential cycling showed mass activity loss of 50% and potential loss of 8 mV (iR-free) at 1.5 A/cm 2. The ECSA loss was 22% after 5,000 cycles. Furthermore, the Pt*/ACCS-2 catalyst showed an initial power density (rated) of 0.174 g PGM/kW. Excellent activity and stability of the catalyst are due to synergistic effect of the catalytic activity and stability of ACCS-2, its enhanced hydrophobicity as well as activity of compressive Pt* lattice catalysts. For the first time, we report a carbon based support which is stable under simulated start-up/shut down operating conditions. Five 25cm 2 MEA’s were fabricated at USC using Pt*/ACCS-2 cathode catalyst for independent evaluation at National Renewable Energy. In the Final NREL report they summarize their results as follow: (1) Initial ORR activity and performance of the USC MEA’s Pt*/ACCS-2 under oxygen air, evaluated at NREL were comparable to that measured and reported by USC in their report: (2) Cyclic durability studies indicate that Pt*/ACCS-2 catalysts has minimal losses in activity and performant under 1-1.5 V potential cycling indicating a robust corrosion resistant support.« less

Fischer-Tropsch activity for non-promoted cobalt-on-alumina catalysts

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2001-01-01

Cobalt catalysts, and processes employing these inventive catalysts, for hydrocarbon synthesis. The inventive catalyst comprises cobalt on an alumina support and is not promoted with any noble or near noble metals. In one aspect of the invention, the alumina support preferably includes a dopant in an amount effective for increasing the activity of the inventive catalyst. The dopant is preferably a titanium dopant. In another aspect of the invention, the cobalt catalyst is preferably reduced in the presence of hydrogen at a water vapor partial pressure effective to increase the activity of the cobalt catalyst for hydrocarbon synthesis. The water vapor partial pressure is preferably in the range of from 0 to about 0.1 atmospheres.

Dual Tuning of Ni-Co-A (A = P, Se, O) Nanosheets by Anion Substitution and Holey Engineering for Efficient Hydrogen Evolution.

PubMed

Fang, Zhiwei; Peng, Lele; Qian, Yumin; Zhang, Xiao; Xie, Yujun; Cha, Judy J; Yu, Guihua

2018-04-18

Seeking earth-abundant electrocatalysts with high efficiency and durability has become the frontier of energy conversion research. Mixed-transition-metal (MTM)-based electrocatalysts, owing to the desirable electrical conductivity, synergistic effect of bimetal atoms, and structural stability, have recently emerged as new-generation hydrogen evolution reaction (HER) electrocatalysts. However, the correlation between anion species and their intrinsic electrocatalytic properties in MTM-based electrocatalysts is still not well understood. Here we present a novel approach to tuning the anion-dependent electrocatalytic characteristics in MTM-based catalyst for HER, using holey Ni/Co-based phosphides/selenides/oxides (Ni-Co-A, A = P, Se, O) as the model materials. The electrochemical results, combined with the electrical conductivity measurement and DFT calculation, reveal that P substitution could modulate the electron configuration, lower the hydrogen adsorption energy, and facilitate the desorption of hydrogen on the active sites in Ni-Co-A holey nanostructures, resulting in superior HER catalytic activity. Accordingly we fabricate the NCP holey nanosheet electrocatalyst for HER with an ultralow onset overpotential of nearly zero, an overpotential of 58 mV, and long-term durability, along with an applied potential of 1.56 V to boost overall water splitting at 10 mA cm -2 , among the best electrocatalysts reported for non-noble-metal catalysts to date. This work not only presents a deeper understanding of the intrinsic HER electrocatalytic properties for MTM-based electrocatalyst with various anion species but also offers new insights to better design efficient and durable water-splitting electrocatalysts.

Supported versus colloidal zinc oxide for advanced oxidation processes

NASA Astrophysics Data System (ADS)

Laxman, Karthik; Al Rashdi, Manal; Al Sabahi, Jamal; Al Abri, Mohammed; Dutta, Joydeep

2017-07-01

Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.

Studies on KIT-6 Supported Cobalt Catalyst for Fischer–Tropsch Synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gnanamani, M.; Jacobs, G; Graham, U

2010-01-01

KIT-6 molecular sieve was used as a support to prepare cobalt catalyst for Fischer-Tropsch synthesis (FTS) using an incipient wetness impregnation method to produce cobalt loadings of 15 and 25 wt%. The catalysts were characterized by BET surface area, X-ray diffraction, scanning transmission election microscopy (STEM), extended X-ray absorption fine spectroscopy and X-ray absorption near edge spectroscopy. The catalytic properties for FTS were evaluated using a 1L CSTR reactor. XRD, pore size distribution, and STEM analysis indicate that the KIT-6 mesostructure remains stable during and after cobalt impregnation and tends to form smaller cobalt particles, probably located inside the mesopores.more » The mesoporous KIT-6 exhibited a slightly higher cobalt dispersion compared to amorphous SiO{sub 2} supported catalyst. With the higher Co loading (25 wt%) on KIT-6, partial structural collapse was observed after the FTS reaction. Compared to an amorphous SiO{sub 2} supported cobalt catalyst, KIT-6 supported cobalt catalyst displayed higher methane selectivity at a similar Co loading, likely due to diffusion effects.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Rong; Zhukhovitskiy, Aleksandr V.; Deraedt, Christophe V.

Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles—some without homogeneous analogues—for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimizemore » and expand the scope of their reactivity and selectivity. Ongoing efforts in our laboratories are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence, and structural uniformity, dendrimers have proven to be versatile scaffolds for the synthesis and stabilization of small nanoclusters. Then these dendrimer-encapsulated metal clusters (DEMCs) are adsorbed onto mesoporous silica. Through this method, we have achieved selective transformations that had been challenging to accomplish in a heterogeneous setting, e.g., π-bond activation and aldol reactions. Extensive investigation into the catalytic systems under reaction conditions allowed us to correlate the structural features (e.g., oxidation states) of the catalysts and their activity. Moreover, we have demonstrated that supported DEMCs are also excellent catalysts for typical heterogeneous reactions, including hydrogenation and alkane isomerization. Critically, these investigations also confirmed that the supported DEMCs are heterogeneous and stable against leaching. Catalysts optimization is achieved through the modulation of various parameters. The clusters are oxidized (e.g., with PhICl 2) or reduced (e.g., with H 2) in situ. Changing the dendrimer properties (e.g., generation, terminal functional groups) is analogous to ligand modification in homogeneous catalysts, which affect both catalytic activity and selectivity. Similarly, pore size of the support is another factor in determining product distribution. In a flow reactor, the flow rate is adjusted to control the residence time of the starting material and intermediates, and thus the final product selectivity. Our approach to heterogeneous catalysis affords various advantages: (1) the catalyst system can tap into the reactivity typical to homogeneous catalysts, which conventional heterogeneous catalysts could not achieve; (2) unlike most homogeneous catalysts with comparable performance, the heterogenized homogeneous catalysts can be recycled; (3) improved activity or selectivity compared to conventional homogeneous catalysts is possible because of uniquely heterogeneous parameters for optimization. Here in this Account, we will briefly introduce metal clusters and describe the synthesis and characterizations of supported DEMCs. We will present the catalysis studies of supported DEMCs in both the batch and flow modes. Lastly, we will summarize the current state of heterogenizing homogeneous catalysis and provide future directions for this area of research.« less

Surface-reconstructed graphite nanofibers as a support for cathode catalysts of fuel cells.

PubMed

Gan, Lin; Du, Hongda; Li, Baohua; Kang, Feiyu

2011-04-07

Graphite nanofibers (GNFs), on which surface graphite edges were reconstructed into nano-loops, were explored as a cathode catalyst support for fuel cells. The high degree of graphitization, as well as the surface-reconstructed nano-loops that possess topological defects for uniform metal deposition, resulted in an improved performance of the GNF-supported Pt catalyst.

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

PubMed

Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

2017-08-09

Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

Methods of making textured catalysts

DOEpatents

Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

2010-08-17

A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Dispersion enhanced metal/zeolite catalysts

DOEpatents

Sachtler, W.M.H.; Tzou, M.S.; Jiang, H.J.

1987-03-31

Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

Dispersion enhanced metal/zeolite catalysts

DOEpatents

Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

1987-01-01

Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

Magnetic Carbon Supported Palladium Nanoparticles: An Efficient and Sustainable Catalyst for Hydrogenation Reactions

EPA Science Inventory

Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; the catalyst can be used for the hydrogenation of alkenes and reduction of aryl nitro compounds.

Second harmonic generation in gallium phosphide photonic crystal nanocavities with ultralow continuous wave pump power.

PubMed

Rivoire, Kelley; Lin, Ziliang; Hatami, Fariba; Masselink, W Ted; Vucković, Jelena

2009-12-07

We demonstrate second harmonic generation in photonic crystal nanocavities fabricated in the semiconductor gallium phosphide. We observe second harmonic radiation at 750 nm with input powers of only nanowatts coupled to the cavity and conversion effciency P(out)/P(2)(in,coupled)=430%/W. The large electronic band gap of GaP minimizes absorption loss, allowing effcient conversion. Our results are promising for integrated, low-power light sources and on-chip reduction of input power in other nonlinear processes.

Magnetic nanoparticles conjugated to chiral imidazolidinone as recoverable catalyst

NASA Astrophysics Data System (ADS)

Mondini, Sara; Puglisi, Alessandra; Benaglia, Maurizio; Ramella, Daniela; Drago, Carmelo; Ferretti, Anna M.; Ponti, Alessandro

2013-11-01

The immobilization of an ad hoc designed chiral imidazolidin-4-one onto iron oxide magnetic nanoparticles (MNPs) is described, to afford MNP-supported MacMillan's catalyst. Morphological and structural analysis of the materials, during preparation, use, and recycle, has been carried out by transmission electron microscopy. The supported catalyst was tested in the Diels-Alder reaction of cyclopentadiene with cinnamic aldehyde, affording the products in good yields and enantiomeric excesses up to 93 %, comparable to those observed with the non-supported catalyst. Recovery of the chiral catalyst has been successfully performed by simply applying an external magnet to achieve a perfect separation of the MNPs from the reaction product. The recycle of the catalytic system has been also investigated. Noteworthy, this immobilized MacMillan's catalyst proved to be able to efficiently promote the reaction in pure water.

Investigating Catalyst–Support Interactions To Improve the Hydrogen Evolution Reaction Activity of Thiomolybdate [Mo 3 S 13 ] 2– Nanoclusters

DOE PAGES

Hellstern, Thomas R.; Kibsgaard, Jakob; Tsai, Charlie; ...

2017-09-22

Molybdenum sulfides have been identified as promising materials for catalyzing the hydrogen evolution reaction (HER) in acid, with active edge sites that exhibit some of the highest turnover frequencies among nonpreciousmetal catalysts. The thiomolybdate [Mo 3S 13] 2- nanocluster catalyst contains a structural motif that resembles the active site of MoS 2 and has been reported to be among the most active forms of molybdenum sulfide. Herein, we improve the activity of the [Mo 3S 13] 2- catalysts through catalyst-support interactions. We synthesize [Mo 3S 13] 2- on gold, silver, glassy carbon, and copper supports to demonstrate the ability tomore » tune the hydrogen binding energy of [Mo 3S 13] 2- using catalyst-support electronic interactions and optimize HER activity.« less

Investigating Catalyst–Support Interactions To Improve the Hydrogen Evolution Reaction Activity of Thiomolybdate [Mo 3 S 13 ] 2– Nanoclusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hellstern, Thomas R.; Kibsgaard, Jakob; Tsai, Charlie

Molybdenum sulfides have been identified as promising materials for catalyzing the hydrogen evolution reaction (HER) in acid, with active edge sites that exhibit some of the highest turnover frequencies among nonpreciousmetal catalysts. The thiomolybdate [Mo 3S 13] 2- nanocluster catalyst contains a structural motif that resembles the active site of MoS 2 and has been reported to be among the most active forms of molybdenum sulfide. Herein, we improve the activity of the [Mo 3S 13] 2- catalysts through catalyst-support interactions. We synthesize [Mo 3S 13] 2- on gold, silver, glassy carbon, and copper supports to demonstrate the ability tomore » tune the hydrogen binding energy of [Mo 3S 13] 2- using catalyst-support electronic interactions and optimize HER activity.« less

Water-gas shift reaction on alumina-supported Pt-CeO x catalysts prepared by supercritical fluid deposition

DOE PAGES

Deal, Jacob W.; Le, Phong; Corey, C. Blake; ...

2016-08-25

Alumina-supported platinum catalysts, both with and without ceria, were prepared by supercritical fluid deposition and evaluated for activity for water-gas shift reaction. The organometallic precursor, platinum(II) acetylacetonate, was deposited from solution in supercritical carbon dioxide. Analysis of the catalysts by high resolution scanning transmission electron microscopy indicated that platinum was present in the form of highly dispersed metal nanoparticles. Pretreatment of the alumina-supported ceria in hydrogen prior to the deposition of the platinum precursor resulted in more platinum nucleated on ceria than non-pretreated alumina-supported ceria but varied in both particle size and structure. The ceria-containing catalyst that was not pretreatedmore » exhibited a more uniform particle size, and the Pt particles were encapsulated in crystalline ceria. Reaction rate measurements showed that the catalyst was more active for water-gas shift, with reaction rates per mass of platinum that exceeded most literature values for water-gas shift reaction on Pt-CeO x catalysts. The high activity was attributed to the significant fraction of platinum/ceria interfacial contact. We found that these results show the promise of supercritical fluid deposition as a scalable means of synthesizing highly active supported metal catalysts that offer efficient utilization of precious metals.« less

A homogeneous, recyclable polymer support for Rh(I)-catalyzed C-C bond formation.

PubMed

Jana, Ranjan; Tunge, Jon A

2011-10-21

A robust and practical polymer-supported, homogeneous, recyclable biphephos rhodium(I) catalyst has been developed for C-C bond formation reactions. Control of polymer molecular weight allowed tuning of the polymer solubility such that the polymer-supported catalyst is soluble in nonpolar solvents and insoluble in polar solvents. Using the supported rhodium catalysts, addition of aryl and vinylboronic acids to the electrophiles such as enones, aldehydes, N-sulfonyl aldimines, and alkynes occurs smoothly to provide products in high yields. Additions of terminal alkynes to enones and industrially relevant hydroformylation reactions have also been successfully carried out. Studies show that the leaching of Rh from the polymer support is low and catalyst recycle can be achieved by simple precipitation and filtration.

A Homogeneous, Recyclable Polymer Support for Rh(I)-Catalyzed C-C Bond Formation

PubMed Central

Jana, Ranjan; Tunge, Jon A.

2011-01-01

A robust and practical polymer-supported, homogeneous, recyclable biphephos rhodium(I) catalyst has been developed for C-C bond formation reactions. Control of polymer molecular weight allowed tuning of the polymer solubility such that the polymer-supported catalyst is soluble in nonpolar solvents and insoluble in polar solvents. Using the supported rhodium catalysts, addition of aryl and vinylboronic acids to the electrophiles such as enones, aldehydes, N-sulfonyl aldimines, and alkynes occurs smoothly to provide products in high yields. Additions of terminal alkynes to enones and industrially relevant hydroformylation reactions have also been successfully carried out. Studies show that the leaching of Rh from the polymer support is low and catalyst recycle can be achieved by simple precipitation and filtration. PMID:21895010

Nanoparticle-supported and magnetically recoverable ruthenium hydroxide catalyst: efficient hydration of nitriles to amides in aqueous medium.

PubMed

Polshettiwar, Vivek; Varma, Rajender S

2009-01-01

Magnetic attraction not filtration: A magnetic nanoparticle-supported ruthenium hydroxide catalyst (see figure) was readily prepared from inexpensive starting materials and shown to catalyze the hydration of nitriles with excellent yield in a benign aqueous medium. Catalyst recovery using an external magnetic field, superior activity, and the inherent stability of the catalyst system are additional sustainable attributes of this protocol.

Ruthenium on rutile catalyst, catalytic system, and method for aqueous phase hydrogenations

DOEpatents

Elliot, Douglas C.; Werpy, Todd A.; Wang, Yong; Frye, Jr., John G.

2001-01-01

An essentially nickel- and rhenium-free catalyst is described comprising ruthenium on a titania support where the titania is greater than 75% rutile. A catalytic system containing a nickel-free catalyst comprising ruthenium on a titania support where the titania is greater than 75% rutile, and a method using this catalyst in the hydrogenation of an organic compound in the aqueous phase is also described.

Electrocatalytic properties of graphite nanofibers-supported platinum catalysts for direct methanol fuel cells.

PubMed

Park, Soo-Jin; Park, Jeong-Min; Seo, Min-Kang

2009-09-01

Graphite nanofibers (GNFs) treated at various temperatures were used as carbon supports to improve the efficiency of PtRu catalysts. The electrochemical properties of the PtRu/GNFs catalysts were then investigated to evaluate their potential for application in DMFCs. The results indicated that the particle size and dispersibility of PtRu in the catalysts were changed by heat treatment, and the electrochemical activity of the catalysts was improved. Consequently, it was found that heat treatments could have an influence on the surface and structural properties of GNFs, resulting in enhancing an electrocatalytic activity of the catalysts for DMFCs.

Partial Oxidation of Hydrocarbons in a Segmented Bed Using Oxide-based Catalysts and Oxygen-conducting Supports

NASA Astrophysics Data System (ADS)

Smith, Mark W.

Two objectives for the catalytic reforming of hydrocarbons to produce synthesis gas are investigated herein: (1) the effect of oxygen-conducting supports with partially substituted mixed-metal oxide catalysts, and (2) a segmented bed approach using different catalyst configurations. Excess carbon deposition was the primary cause of catalyst deactivation, and was the focus of the experiments for both objectives. The formation and characterization of deposited carbon was examined after reaction for one of the selected catalysts to determine the quantity and location of the carbon on the catalyst surface leading to deactivation. A nickel-substituted barium hexaaluminate (BNHA), with the formula BaAl 11.6Ni0.4O18.8, and a Rh-substituted lanthanum zirconate pyrochlore (LCZR) with the formula La1.89Ca0.11 Zr1.89Rh0.11, were combined with two different doped ceria supports. These supports were gadolinium-doped ceria (GDC) and zirconium-doped ceria (ZDC). The active catalyst phases were combined with the supports in different ratios using different synthesis techniques. The catalysts were characterized using several different techniques and were tested under partial oxidation (POX) of n-tetradecane (TD), a diesel fuel surrogate. It was found that the presence of GDC and ZDC reduced the formation of carbon for both catalysts; the optimal ratio of catalyst to support was different for the hexaaluminate and the pyrochlore; a loading of 20 wt% of the pyrochlore with ZDC produced the most stable performance in the presence of common fuel contaminants (>50 h); and, the incipient wetness impregnation synthesis method of applying the active catalyst to the support produced more stable product yields than the catalyst prepared by a solid-state mixing technique. Different hexaaluminate and pyrochlore catalysts were used in different configurations in a segmented bed approach. The first strategy was to promote the indirect reforming mechanism by placing a combustion catalyst in the reactor inlet, followed by a reforming catalyst. This approach demonstrated that BNHA can be used in the reactor inlet to promote combustion with 1 wt% Rh-substituted pyrochlore in the reactor outlet, but the combustion catalyst should fill less than 50% of the reactor. The second approach placed specific catalysts in regions of the reactor that have conditions in which they are less likely to deactivate. This showed the most benefit in the use of a sulfur-tolerant noble metal catalyst in the reactor outlet. The carbon formation study was conducted on a 2 wt% Rh-substituted pyrochlore. POX of TD for various run times, followed by temperature programmed oxidation, revealed two different types of carbon deposits in the catalyst bed: carbon that burned off at relatively low temperature (LTC), and carbon that burned off at higher temperatures (HTC). The LTC reached a steady state level within two hours of reaction, and was determined not to lead to catalyst deactivation. The HTC continued to accumulate with time on stream. A mathematical expression was developed to predict the rate of formation of the HTC for a given set of reaction conditions (O/C = 1.25). This expression was modified from data from a test under different reaction conditions (O/C = 1.1) for one length of time, and was found to predict the carbon formation for a different run time within 3%.

An Investigation of Methyl Viologen Functionalized Reduced Graphene Oxide: Chitosan as a Support for Pt Nanoparticles Towards Ethanol Electrooxidation

NASA Astrophysics Data System (ADS)

Ekrami-Kakhki, Mehri-Saddat; Farzaneh, Nahid; Abbasi, Sedigheh; Beitollahi, Hadi; Ekrami-Kakhki, Seyed Ali

2018-05-01

In this research, graphene oxide was prepared by a modified Hummers' method, and then functionalized with 1, 1'-dimethyl-4, 4'-bipyridinium dichloride (MV), and chitosan (CH) to get a MV-RGO-CH support. Pt nanoparticles were prepared on this support to get Pt/MV-RGO-CH catalyst. The morphology and microstructure of Pt/MV-RGO-CH catalyst were characterized with transmission electron microscopy image and X-ray diffraction analysis. The electrocatalytic activity of the prepared catalyst towards ethanol oxidation was investigated by carbon monoxide stripping voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. The effects of some experimental parameters such as scan rate, ethanol concentration, and temperature were investigated for ethanol electrooxidation at Pt/MV-RGO-CH catalyst. Durability of the catalyst was also investigated. The electrocatalytic performance of Pt/MV-RGO-CH catalyst for ethanol oxidation was compared with those of Pt/CH and Pt/MV-RGO catalysts. The higher electrocatalytic performance of Pt/MV-RGO-CH than Pt/CH and Pt/MV-RGO catalysts towards ethanol electrooxidation indicated that Pt/MV-RGO-CH could be a promising catalyst for application in direct ethanol fuel cells.

Nanoparticle-supported and magnetically recoverable palladium (Pd) catalyst: a selective and sustainable oxidation protocol with high turnover number

EPA Science Inventory

A magnetic nanoparticle-supported ruthenium hydroxide catalyst was readily prepared from inexpensive starting materials and shown to catalyze hydration of nitriles with excellent yield in benign aqueous medium. Catalyst recovery using an external magnetic field, superior activity...

Magnetic silica supported palladium catalyst: synthesis of allyl aryl ethers in water

EPA Science Inventory

A simple and benign procedure for the synthesis of aryl allyl ethers has been developed using phenols, allyl acetates and magnetically recyclable silica supported palladium catalyst in water; performance of reaction in air and easy separation of the catalyst using an external mag...

Hydrocarbon synthesis catalyst and method of preparation

DOEpatents

Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

1983-08-02

A catalyst for the synthesis of hydrocarbons from carbon monoxide and hydrogen composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants. The catalyst is preferably used in dilute slurry form, which is desirable from a heat transfer standpoint. 9 figs.

Hydrocarbon synthesis catalyst and method of preparation

DOEpatents

Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

1983-08-02

A catalyst for the synthesis of hydrocarbons from carbon monoxide and hydrogen composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants. The catalyst is preferably used in dilute slurry form, which is desirable from a heat transfer standpoint.

Textured catalysts, methods of making textured catalysts, and methods of catalyzing reactions conducted in hydrothermal conditions

DOEpatents

Werpy, Todd [West Richland, WA; Wang, Yong [Richland, WA

2003-12-30

A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Preparation of Ru-doped SnO2-supported Pt catalysts and their electrocatalytic properties for methanol oxidation.

PubMed

Pang, H L; Zhang, X H; Zhong, X X; Liu, B; Wei, X G; Kuang, Y F; Chen, J H

2008-03-01

Ru-doped SnO2 nanoparticles were prepared by chemical precipitation and calcinations at 823 K. Due to high stability in diluted acidic solution, Ru-doped SnO2 nanoparticles were selected as the catalyst support and second catalyst for methanol electrooxidation. The micrograph, elemental composition, and structure of the Ru-doped SnO2 nanoparticles were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, respectively. The electrocatalytic properties of the Ru-doped SnO2-supported Pt catalyst (Pt/Ru-doped SnO2) for methanol oxidation have been investigated by cyclic voltammetry. Under the same loading mass of Pt, the Pt/Ru-doped SnO2 catalyst shows better electrocatalytic performance than the Pt/SnO2 catalyst and the best atomic ratio of Ru to Sn in Ru-doped SnO2 is 1/75. Additionally, the Pt/Ru-doped SnO2 catalyst possesses good long-term cycle stability.

Hot charcoal vomitus in aluminum phosphide poisoning - A case report of internal thermal reaction in aluminum phosphide poisoning and review of literature

PubMed Central

Mirakbari, Seyed Mostafa

2015-01-01

Aluminium phosphide (ALP) poisoning is a commonly encountered poisoning in emergency departments in most developing countries. Many papers have revealed metabolic derangements in this poisoning and also examined contributing factors leading to death, but only few have reported physical damage. Some case reports have described a complication that has been frequently termed ‘ignition’. The exact mechanism of this phenomenon has not been fully elucidated. An exothermic reaction during therapeutic administration of chemicals may contribute to this problem, but the incidence has occurred in the absence of treatment or drug administration. Here, we report a 34-year-old woman with ALP poisoning who presented with hot charcoal vomitus, a sign of internal thermal event, leading to the thermal burning of the patient's face and internal damage resulting in death. We reviewed all reported cases with similar complication to demonstrate varied characteristics of patients and to propose the possible mechanisms leading to this event. PMID:26257417

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass.

PubMed

Emmer, Hal; Chen, Christopher T; Saive, Rebecca; Friedrich, Dennis; Horie, Yu; Arbabi, Amir; Faraon, Andrei; Atwater, Harry A

2017-07-05

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnesses below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17  cm -3 that exhibited mobilities as high as 16 cm 2 V -1 s -1 . Due to their unique optical properties, these films hold much promise for use in advanced optical devices.

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass

DOE PAGES

Emmer, Hal; Chen, Christopher T.; Saive, Rebecca; ...

2017-07-05

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnessesmore » below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17 cm -3 that exhibited mobilities as high as 16 cm 2V -1s -1. Therefore, due to their unique optical properties, these films hold much promise for use in advanced optical devices.« less

Cobalt phosphide based nanostructures as bifunctional electrocatalysts for low temperature alkaline water splitting

DOE PAGES

Lambert, Timothy N.; Vigil, Julian A.; Christensen, Ben

2016-08-22

Cobalt phosphide based thin films and nanoparticles were prepared by the thermal phosphidation of spinel Co 3O 4 precursor films and nanoparticles, respectively. CoP films were prepared with overall retention of the Co 3O 4 nanoplatelet morphology while the spherical/cubic Co 3O 4 and Ni 0.15Co 2.85O 4 nanoparticles were converted to nanorods or nanoparticles, respectively. The inclusion of nickel in the nanoparticles resulted in a 2.5 fold higher surface area leading to higher gravimetric performance. In each case high surface area structures were obtained with CoP as the primary phase. All materials were found to act as effective bifunctionalmore » electrocatalysts for both the HER and the OER and compared well to commercial precious metal benchmark materials in alkaline electrolyte. As a result, a symmetrical water electrolysis cell prepared from the CoP-based film operated at a low overpotential of 0.41-0.51 V.« less

Fabrication of Single Crystal Gallium Phosphide Thin Films on Glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emmer, Hal; Chen, Christopher T.; Saive, Rebecca

Due to its high refractive index and low absorption coefficient, gallium phosphide is an ideal material for photonic structures targeted at the visible wavelengths. However, these properties are only realized with high quality epitaxial growth, which limits substrate choice and thus possible photonic applications. In this work, we report the fabrication of single crystal gallium phosphide thin films on transparent glass substrates via transfer bonding. GaP thin films on Si (001) and (112) grown by MOCVD are bonded to glass, and then the growth substrate is removed with a XeF 2 vapor etch. The resulting GaP films have surface roughnessesmore » below 1 nm RMS and exhibit room temperature band edge photoluminescence. Magnesium doping yielded p-type films with a carrier density of 1.6 × 10 17 cm -3 that exhibited mobilities as high as 16 cm 2V -1s -1. Therefore, due to their unique optical properties, these films hold much promise for use in advanced optical devices.« less

Recent developments in indium phosphide space solar cell research

NASA Technical Reports Server (NTRS)

Brinker, David J.; Weinberg, Irving

1987-01-01

Recent developments and progress in indium phosphide solar cell research for space application are reviewed. Indium phosphide homojunction cells were fabricated in both the n+p and p+n configurations with total area efficiencies of 17.9 and 15.9% (air mass 0 and 25 C) respectively. Organometallic chemical vapor deposition, liquid phase epitaxy, ion implantation and diffusion techniques were employed in InP cell fabrication. A theoretical model of a radiation tolerant, high efficiency homojunction cell was developed. A realistically attainable AMO efficiency of 20.5% was calculated using this model with emitter and base doping of 6 x 10 to the 17th power and 5 x 10 the the 16th power/cu cm respectively. Cells of both configurations were irradiated with 1 MeV electrons and 37 MeV protons. For both proton and electron irradiation, the n+p cells are more radiation resistant at higher fluences than the p+n cells. The first flight module of four InP cells was assembled for the Living Plume Shield III satellite.

In-depth survey report of Early and Daniel Co. , Inc. , Louisville, Kentucky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaebst, D.D.

1986-09-01

An in-depth industrial hygiene survey was conducted to evaluate worker exposures to phosphine during fumigation of grain at the Early and Daniel Co. grain elevator in Louisville, Kentucky. Stored grain was fumigated using aluminum phosphide. Aluminum-phosphide pellets were also added directly to the grain by the blender as it was poured into the storage containers. Local exhaust ventilation was used at points in the grain-moving system where grain dust was generated. Air samples were taken during full-shift periods at the breathing zone of the weighmaster, two bin floormen, and the blender. Area monitoring samples were also taken. If the operatorsmore » spend considerable time in the vicinity of a bin which is being filled with grain, there is a likelihood of far greater exposure levels being noted. According to the author, further studies of the use of phosphide products at other elevators should be conducted to determine the effect of environmental and process parameters on phosphine exposures.« less

Steam Reforming of Acetic Acid over Co-Supported Catalysts: Coupling Ketonization for Greater Stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, Stephen D.; Spies, Kurt A.; Mei, Donghai

We report on the markedly improved stability of a novel 2-bed catalytic system, as compared to a conventional 1-bed steam reforming catalyst, for the production of H2 from acetic acid. The 2-bed catalytic system comprises of i) a basic oxide ketonization catalyst for the conversion of acetic acid to acetone, and a ii) Co-based steam reforming catalyst, both catalytic beds placed in sequence within the same unit operation. Steam reforming catalysts are particularly prone to catalytic deactivation when steam reforming acetic acid, used here as a model compound for the aqueous fraction of bio-oil. Catalysts comprising MgAl2O4, ZnO, CeO2, andmore » activated carbon (AC) both with and without Co-addition were evaluated for conversion of acetic acid and acetone, its ketonization product, in the presence of steam. It was found that over the bare oxide support only ketonization activity was observed and coke deposition was minimal. With addition of Co to the oxide support steam reforming activity was facilitated and coke deposition was significantly increased. Acetone steam reforming over the same Co-supported catalysts demonstrated more stable performance and with less coke deposition than with acetic acid feedstock. DFT analysis suggests that over Co surface CHxCOO species are more favorably formed from acetic acid versus acetone. These CHxCOO species are strongly bound to the Co catalyst surface and could explain the higher propensity for coke formation from acetic acid. Based on these findings, in order to enhance stability of the steam reforming catalyst a dual-bed (2-bed) catalyst system was implemented. Comparing the 2-bed and 1-bed (Co-supported catalyst only) systems under otherwise identical reaction conditions the 2-bed demonstrated significantly improved stability and coke deposition was decreased by a factor of 4.« less

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

PubMed Central

dos Santos, Antonio Rodolfo; Kunz, Ulrich; Turek, Thomas

2011-01-01

Summary In this contribution we present for the first time a continuous process for the production of highly active Pt catalysts supported by carbon nanotubes by use of an electrically heated tubular reactor. The synthesized catalysts show a high degree of dispersion and narrow distributions of cluster sizes. In comparison to catalysts synthesized by the conventional oil-bath method a significantly higher electrocatalytic activity was reached, which can be attributed to the higher metal loading and smaller and more uniformly distributed Pt particles on the carbon support. Our approach introduces a simple, time-saving and cost-efficient method for fuel cell catalyst preparation in a flow reactor which could be used at a large scale. PMID:22043252

Highly Efficient Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Gold Supported on Zinc Oxide Materials

DOE PAGES

Chen, Hangning; Cullen, David A.; Larese, J. Z.

2015-11-30

We used Au/ZnO catalysts for liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol and compared with Au/Fe 2O 3 catalysts. To investigate the influence of the support on the hydrogenation activity and selectivity, three different Au/ZnO catalysts were synthesized, including Au/rod-tetrapod ZnO, Au/porous ZnO, and Au/ZnO-CP prepared using a coprecipitation method. Moreover, the influence of calcination temperature was also systematically investigated in this study. The characterization of Au/ZnO catalysts was performed using ICP, N 2 adsorption/desorption isotherms, X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy. Among all the supported Au catalysts prepared in this study, Au/ZnO-CP exhibits bothmore » the highest hydrogenation activity and selectivity. Using a 1.5% Au/ZnO-CP catalyst, 100% selectivity could be achieved with 94.9% conversion. Finally, we find that the Au particle (size and shape), the ZnO support (size and surface texture) and the interaction between Au and ZnO are three important parameters for achieving a highly efficient Au/ZnO catalyst.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mei, Donghai; Lebarbier, Vanessa M.; Rousseau, Roger

In a combined experimental and first-principles density functional theory (DFT) study, benzene steam reforming (BSR) over MgAl 2O 4 supported Rh and Ir catalysts was investigated. Experimentally, it has been found that both highly dispersed Rh and Ir clusters (1-2 nm) on the MgAl 2O 4 spinel support are stable during the BSR in the temperature range of 700-850°C. Compared to the Ir/MgAl 2O 4 catalyst, the Rh/MgAl 2O 4 catalyst is more active with higher benzene turnover frequency and conversion. At typical steam conditions with the steam-to-carbon ratio > 12, the benzene conversion is only a weak function ofmore » the H 2O concentration in the feed. This suggests that the initial benzene decomposition step rather than the benzene adsorption is most likely the rate-determined step in BSR over supported Rh and Ir catalysts. In order to understand the differences between the two catalysts, we followed with a comparative DFT study of initial benzene decomposition pathways over two representative model systems for each supported metal (Rh and Ir) catalysts. A periodic terrace (111) surface and an amorphous 50-atom metal cluster with a diameter of 1.0 nm were used to represent the two supported model catalysts under low and high dispersion conditions. Our DFT results show that the decreasing catalyst particle size enhances the benzene decomposition on supported Rh catalysts by lowering both C-C and C-H bond scission. The activation barriers of the C-C and the C-H bond scission decrease from 1.60 and 1.61 eV on the Rh(111) surface to 1.34 and 1.26 eV on the Rh50 cluster. For supported Ir catalysts, the decreasing particle size only affects the C-C scission. The activation barrier of the C-C scission of benzene decreases from 1.60 eV on the Ir(111) surface to 1.35 eV on the Ir50 cluster while the barriers of the C-H scission are practically the same. The experimentally measured higher BSR activity on the supported highly dispersed Rh catalyst can be rationalized by the thermodynamic limitation for the very first C-C bond scission of benzene on the small Ir50 catalyst. The C-C bond scission of benzene on the small Ir50 catalyst is highly endothermic although the barrier is competitive with the barriers of both the C-C and the C-H bond-breakings on the small Rh50 catalyst. The calculations also imply that, for the supported Rh catalysts the C-C and C-H bond scissions are competitive, independently of the Rh cluster sizes. After the initial dissociation step via either the C-C or the C-H bond scission, the C-H bond breaking seems to be more favorable rather than the C-C bond breaking on the larger Rh terrace surface. This work was financially supported by the United States Department of Energy’s Office of Biomass Program’s. Computing time was granted by a user project at the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.« less

Autothermal reforming catalyst having perovskite structure

DOEpatents

Krumpel, Michael [Naperville, IL; Liu, Di-Jia [Naperville, IL

2009-03-24

The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

Metal catalysts for steam reforming of tar derived from the gasification of lignocellulosic biomass.

PubMed

Li, Dalin; Tamura, Masazumi; Nakagawa, Yoshinao; Tomishige, Keiichi

2015-02-01

Biomass gasification is one of the most important technologies for the conversion of biomass to electricity, fuels, and chemicals. The main obstacle preventing the commercial application of this technology is the presence of tar in the product gas. Catalytic reforming of tar appears a promising approach to remove tar and supported metal catalysts are among the most effective catalysts. Nevertheless, improvement of catalytic performances including activity, stability, resistance to coke deposition and aggregation of metal particles, as well as catalyst regenerability is greatly needed. This review focuses on the design and catalysis of supported metal catalysts for the removal of tar in the gasification of biomass. The recent development of metal catalysts including Rh, Ni, Co, and their alloys for steam reforming of biomass tar and tar model compounds is introduced. The role of metal species, support materials, promoters, and their interfaces is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

Graphene supported heterogeneous catalysts for Li-O2 batteries

NASA Astrophysics Data System (ADS)

Alaf, M.; Tocoglu, U.; Kartal, M.; Akbulut, H.

2016-09-01

In this study production and characterization of free-standing and flexible (i) graphene, (ii) α-MnO2/graphene, (iii) Pt/graphene (iv) α-MnO2/Pt/graphene composite cathodes for Li-air batteries were reported. Graphene supported heterogeneous catalysts were produced by a facile method. In order to prevent aggregation of graphene sheets and increase not only interlayer distance but also surface area, a trace amount multi-wall carbon nano tube (MWCNT) was introduced to the composite structure. The obtained composite catalysts were characterized by SEM, X-ray diffraction, N2 adsorption-desorption analyze and Raman spectroscopy. The electrochemical characterization tests including galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurement of catalyst were carried out by using an ECC-Air test cell. These highly active graphene supported heterogeneous composite catalysts provide competitive properties relative to other catalyst materials for Li-air batteries.

Novel elastic, lattice dynamics and thermodynamic properties of metallic single-layer transition metal phosphides: 2H-M 2P (Mo2P, W2P, Nb2P and Ta2P)

NASA Astrophysics Data System (ADS)

Yin, Jiuren; Wu, Bozhao; Wang, Yanggang; Li, Zhimi; Yao, Yuanpeng; Jiang, Yong; Ding, Yanhuai; Xu, Fu; Zhang, Ping

2018-04-01

Recently, there has been a surge of interest in the research of two-dimensional (2D) phosphides due to their unique physical properties and wide applications. Transition metal phosphides 2H-M 2Ps (Mo2P, W2P, Nb2P and Ta2P) show considerable catalytic activity and energy storage potential. However, the electronic structure and mechanical properties of 2D 2H-M 2Ps are still unrevealed. Here, first-principles calculations are employed to investigate the lattice dynamics, elasticity and thermodynamic properties of 2H-M 2Ps. Results show that M 2Ps with lower stiffness exhibit remarkable lateral deformation under unidirectional loads. Due to the largest average Grüneisen parameter, single-layer Nb2P has the strongest anharmonic vibrations, resulting in the highest thermal expansion coefficient. The lattice thermal conductivities of Ta2P, W2P and Nb2P contradict classical theory, which would predict a smaller thermal conductivity due to the much heavier atom mass. Moreover, the calculations also demonstrate that the thermal conductivity of Ta2P is the highest as well as the lowest thermal expansion, owing to its weak anharmonic phonon scattering and the lowest average Grüneisen parameter. The insight provided by this study may be useful for future experimental and theoretical studies concerning 2D transition metal phosphide materials.

Electrocatalytic activity of cobalt phosphide-modified graphite felt toward VO2+/VO2+ redox reaction

NASA Astrophysics Data System (ADS)

Ge, Zhijun; Wang, Ling; He, Zhangxing; Li, Yuehua; Jiang, Yingqiao; Meng, Wei; Dai, Lei

2018-04-01

A novel strategy for improving the electro-catalytic properties of graphite felt (GF) electrode in vanadium redox flow battery (VRFB) is designed by depositing cobalt phosphide (CoP) onto GF surface. The CoP powder is synthesized by direct carbonization of Co-based zeolitic imidazolate framework (ZIF-67) followed by phosphidation. Cyclic voltammetry results confirm that the CoP-modified graphite felt (GF-CoP) electrode has excellent reversibility and electro-catalytic activity to the VO2+/VO2+ cathodic reaction compared with the pristine GF electrode. The cell using GF-CoP electrode shows apparently higher discharge capacity over that based on GF electrode. The cell using GF-CoP electrode has the capacity of 67.2 mA h at 100 mA cm-2, 32.7 mA h larger than that using GF electrode. Compared with cell using GF electrode, the voltage efficiency of the cell based on GF-CoP electrode increases by 5.9% and energy efficiency by 5.4% at a current density of 100 mA cm-2. The cell using GF-CoP electrode can reach 94.31% capacity retention after 50 cycles at a current density of 30 mA cm-2. The results show that the CoP can effectively promote the VO2+/VO2+ redox reaction, implying that metal phosphides are a new kind of potential catalytic materials for VRFB.

Catalyst containing oxygen transport membrane

DOEpatents

Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

2012-12-04

A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

The effect of activated carbon support surface modification on characteristics of carbon nanospheres prepared by deposition precipitation of Fe-catalyst

NASA Astrophysics Data System (ADS)

Kristianto, H.; Arie, A. A.; Susanti, R. F.; Halim, M.; Lee, J. K.

2016-11-01

In this study the effect of activated carbon support modification to synthesis of CNSs was observed. Modification of activated carbon was done by using nitric acid. The effect of modification was analyzed from its FTIR spectra. The Fe catalysts were deposited on to the support by using urea deposition precipitation method at various initial catalysts concentration. CNSs was synthesized by utilizing cooking palm oil as renewable carbon source, and pyrolized at 700°C for 1 hour under nitrogen atmosphere. The products obtained then analyzed using SEM-EDS, TEM, XRD, and Raman spectroscopy. The modification of activated carbon support had increased the oxygen functional group. This increase resulted on increase of metal catalysts deposited on activated carbon surface. Peak of C (100) was observed, while ID/IG of samples were obtained around 0.9, which is commonly obtained for CNSs. High catalysts loading on modified activated carbon support caused decomposition of CNSs and formation carbon onion.

Preparation of Supported Palladium Catalysts using Deep Eutectic Solvents.

PubMed

Iwanow, Melanie; Finkelmeyer, Jasmin; Söldner, Anika; Kaiser, Manuela; Gärtner, Tobias; Sieber, Volker; König, Burkhard

2017-09-12

Deep eutectic solvents (DESs) dissolve metal salts or oxides and are used as solvent and carbon source for the preparation of supported palladium catalysts. After dissolving of the palladium salt in the DES, the pyrolysis of the mixture under nitrogen atmosphere yields catalytically active palladium on supporting material composed of carbon, nitrogen and oxygen (CNO) by a simple single step preparation method without further activation. The catalysts were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and CHNS/O elementary analysis. The amount of functional groups on the surface of the supporting material was determined by Boehm titrations. Moreover, the activity of the prepared catalysts was evaluated in the hydrogenation of linear alkenes and compared with a commercial Pd/C catalyst. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon nanocages: a new support material for Pt catalyst with remarkably high durability.

PubMed

Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

2014-03-24

Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for "real world" application.

Methods for making a supported iron-copper catalyst

DOEpatents

Dyer, Paul N.; Pierantozzi, Ronald

1986-01-01

A catalyst is described for the synthesis of hydrocarbons from CO+H.sub.2 utilizing a porous Al.sub.2 O.sub.3 support impregnated with iron and copper and optionally promoted with an alkali metal. The use of an Al.sub.2 O.sub.3 support results in the suppression of heavy waxes (C.sub.26 + hydrocarbons), particularly in slurry phase operation, when compared to unsupported or co-precipitated catalysts.

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

NASA Astrophysics Data System (ADS)

Islam, A. E.; Nikolaev, P.; Amama, P. B.; Zakharov, D.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Stach, E. A.; Maruyama, B.

2015-09-01

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. With the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

Carbon nanotubes grown on bulk materials and methods for fabrication

DOEpatents

Menchhofer, Paul A [Clinton, TN; Montgomery, Frederick C [Oak Ridge, TN; Baker, Frederick S [Oak Ridge, TN

2011-11-08

Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

PubMed

Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

2015-03-06

Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. Copyright © 2014 Elsevier Ltd. All rights reserved.

Understanding of catalyst deactivation caused by sulfur poisoning and carbon deposition in steam reforming of liquid hydrocarbon fuels

NASA Astrophysics Data System (ADS)

Xie, Chao

2011-12-01

The present work was conducted to develop a better understanding on the catalyst deactivation in steam reforming of sulfur-containing liquid hydrocarbon fuels for hydrogen production. Steam reforming of Norpar13 (a liquid hydrocarbon fuel from Exxon Mobile) without and with sulfur was performed on various metal catalysts (Rh, Ru, Pt, Pd, and Ni) supported on different materials (Al2O3, CeO2, SiO2, MgO, and CeO2- Al2O3). A number of characterization techniques were applied to study the physicochemical properties of these catalysts before and after the reactions. Especially, X-ray absorption near edge structure (XANES) spectroscopy was intensively used to investigate the nature of sulfur and carbon species in the used catalysts to reveal the catalyst deactivation mechanism. Among the tested noble metal catalysts (Rh, Ru, Pt, and Pd), Rh catalyst is the most sulfur tolerant. Al2O3 and CeO2 are much better than SiO2 and MgO as the supports for the Rh catalyst to reform sulfur-containing hydrocarbons. The good sulfur tolerance of Rh/Al2O3 can be attributed to the acidic nature of the Al2O3 support and its small Rh crystallites (1-3 nm) as these characteristics facilitate the formation of electron-deficient Rh particles with high sulfur tolerance. The good catalytic performance of Rh/CeO2 in the presence of sulfur can be ascribed to the promotion effect of CeO2 on carbon gasification, which significantly reduced the carbon deposition on the Rh/CeO2catalyst. Steam reforming of Norpar13 in the absence and presence of sulfur was further carried out over CeO2-Al2O3 supported monometallic Ni and Rh and bimetallic Rh-Ni catalysts at 550 and 800 °C. Both monometallic catalysts rapidly deactivated at 550 °C, iv and showed poor sulfur tolerance. Although ineffective for the Ni catalyst, increasing the temperature to 800 °C dramatically improved the sulfur tolerance of the Rh catalyst. Sulfur K-edge XANES revealed that metal sulfide and organic sulfide are the dominant sulfur species on the used Ni catalyst, while sulfonate and sulfate predominate on the used Rh catalyst. The superior sulfur tolerance of the Rh/CeO2-Al2O3 catalyst at 800 °C may be associated with its capability in sulfur oxidation. It is very likely that the oxygenshielded sulfur structure of sulfonate and sulfate can suppress the poisoning impact of sulfur on Rh through inhibiting direct rhodium-sulfur interaction. Although the Rh-Ni catalyst exhibited better sulfur tolerance than the monometallic ones at 550 °C, its catalytic performance was inferior compared with the Rh catalyst in the sulfur-containing reaction at 800 °C probably due to the severe carbon deposition on the bimetallic catalyst. The last part of this work focuses on the influence of sulfur on the carbon deposition in steam reforming of liquid hydrocarbon fuels over CeO2-Al2O3 supported monometallic Ni and Rh catalysts at 800 ºC. Though abundant carbon deposits can accumulate on the pure CeO2-Al2O3 support due to fuel thermal cracking, the metal addition substantially mitigated the carbon deposition in the sulfur-free reaction. The presence of sulfur increased the carbon deposition on both catalysts, which has a much more significant impact for the Ni catalyst. Our results indicate that (I) the presence of sulfur can suppress carbon gasification and promote the formation of graphitic carbon on reforming catalysts, and (II) the Rh catalyst possesses stronger capability to maintain carbon gasification activity than the Ni catalyst in the presence of sulfur.

Microwave assisted synthesis of biarlys by Csbnd C coupling reactions with a new chitosan supported Pd(II) catalyst

NASA Astrophysics Data System (ADS)

Baran, Talat; Menteş, Ayfer

2016-10-01

In this study a new type chitosan-based support has been produced for Pd(II) catalyst and its catalytic performance in Suzuki Csbnd C reactions has been studied under microwave irradiation without using any solvent. The chemical identification of the catalyst was performed using TG/DTG, FTIR, UV-Vis ICP-OES, SEM/EDAX, 13C NMR, molar conductivity, XRD and magnetic moment techniques. The performance of this new Pd(II) catalyst was studied in Suzuki Csbnd C reactions. The Pd(II) catalyst exhibited a good catalytic performance in very short time (4 min) by giving high TONs and TOFs with low amount of the catalyst (0.015 mol%). The catalyst also had reusability and did not lose its activity until six runs.

Effect of Graphitic Content on Carbon Supported Catalyst Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen

2011-07-01

The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150oC and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metalic content, however they also showed depressed catalyticmore » activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Chao; Chen, Yongsheng; Engelhard, Mark H.

This work was conducted to clarify the influence of the type of metal and support on the sulfur tolerance and carbon resistance of supported noble metal catalysts in steam reforming of liquid hydrocarbons. Al2O3-supported noble metal catalysts (Rh, Ru, Pt, and Pd), Rh catalysts on different supports (Al2O3, CeO2, SiO2, and MgO), and Pt catalyst supported on CeO2 and Al2O3, were examined for steam reforming of a liquid hydrocarbon fuel (Norpar13 from Exxon Mobil) at 800 C for 55 h. The results indicate that (1) Rh/Al2O3 shows higher sulfur tolerance than the Ru, Pt, and Pd catalysts on the samemore » support; (2) both Al2O3 and CeO2 are promising supports for Rh catalyst to process sulfur-containing hydrocarbons; and (3) Pt/CeO2 exhibits better catalytic performance than Pt/Al2O3 in the reaction with sulfur. TEM results demonstrate that the metal particles in Rh/Al2O3 were better dispersed (mostly in 1-3 nm) compared with the other catalysts after reforming the sulfur-containing feed. As revealed by XPS, the binding energy of Rh 3d for Rh/Al2O3 is notably higher than that for Rh/CeO2, implying the formation of electron-deficient Rh particles in the former. The strong sulfur tolerance of Rh/Al2O3 may be related to the formation of well-dispersed electron-deficient Rh particles on the Al2O3 support. Sulfur K-edge XANES illustrates the preferential formation of sulfonate and sulfate on Rh/Al2O3, which is believed to be beneficial for improving its sulfur tolerance as their oxygen-shielded sulfur structure may hinder direct Rh-S interaction. Due to its strong sulfur tolerance, the carbon deposition on Rh/Al2O3 was significantly lower than that on the Al2O3-supported Ru, Pt, and Pd catalysts after the reaction with sulfur. The superior catalytic performance of CeO2-supported Rh and Pt catalysts in the presence of sulfur can be ascribed mainly to the promotion effect of CeO2 on carbon gasification, leading to much lower carbon deposition compared with the Rh/Al2O3, Rh/MgO, Rh/SiO2 and Pt/Al2O3 catalysts.« less

Dehydration of glycerol over niobia-supported silicotungstic acid catalysts.

PubMed

Lee, Young Yi; Ok, Hye Jeong; Moon, Dong Ju; Kim, Jong Ho; Park, Nam Cook; Kim, Young Chul

2013-01-01

Liquid-phase dehydration of glycerol to acrolein over nanosized niobia-supported silicotungstic acid catalysts was performed to investigate the effect of the silicotungstic acid loading on the catalytic performance of the catalysts. The catalysts were prepared by following an impregnation method with different HSiW loadings in the range of 10-50 wt%. The prepared catalysts were characterized by N2 physisorption, XRD, FT-IR, TPD of ammonia, and TGA. Dehydration of glycerol was conducted in an autoclave reactor under the conditions of controlled reaction temperatures under corresponding pressure. Increasing HSiW loading rapidly increased the acidity of HSiW/Nb205 catalyst and rate of glycerol conversion, but acrolein selectivity decreased due to enhanced deactivation of the catalyst by carbon deposit. Consequently, it was confirmed that catalytic activity for the dehydration of glycerol to acrolein was dependant on the acidity of catalyst and can be controlled by HSiW loading.

NiO-PTA supported on ZIF-8 as a highly effective catalyst for hydrocracking of Jatropha oil

PubMed Central

Liu, Jing; He, Jing; Wang, Luying; Li, Rong; Chen, Pan; Rao, Xin; Deng, Lihong; Rong, Long; Lei, Jiandu

2016-01-01

Nickel oxide (NiO) and phosphotungstic acid (PTA) supported on a ZIF-8 (NiO-PTA/ZIF-8) catalyst was first synthesized and it showed high activity and good selectivity for the hydrocracking of Jatropha oil. The catalyst was characterized by SEM, SEM-EDS, TEM, N2 adsorption, FT-IR, XRD and XPS. Compared with the NiO-PTA/Al2O3 catalyst, the selectivity of C15-C18 hydrocarbon increased over 36%, and catalytic efficiency increased 10 times over the NiO-PTA/ZIF-8 catalyst. The prepared NiO-PTA/ZIF-8 catalyst was stable for a reaction time of 104 h and the kinetic behavior was also analyzed. This catalyst was found to bypass the presulfurization process, showing promise as an alternative to sulfided catalysts for green diesel production. PMID:27020579

Nanoscale Catalysts for NMR Signal Enhancement by Reversible Exchange

PubMed Central

2015-01-01

Two types of nanoscale catalysts were created to explore NMR signal enhancement via reversible exchange (SABRE) at the interface between heterogeneous and homogeneous conditions. Nanoparticle and polymer comb variants were synthesized by covalently tethering Ir-based organometallic catalysts to support materials composed of TiO2/PMAA (poly(methacrylic acid)) and PVP (polyvinylpyridine), respectively, and characterized by AAS, NMR, and DLS. Following parahydrogen (pH2) gas delivery to mixtures containing one type of “nano-SABRE” catalyst particle, a target substrate, and ethanol, up to ∼(−)40-fold and ∼(−)7-fold 1H NMR signal enhancements were observed for pyridine substrates using the nanoparticle and polymer comb catalysts, respectively, following transfer to high field (9.4 T). These enhancements appear to result from intact particles and not from any catalyst molecules leaching from their supports; unlike the case with homogeneous SABRE catalysts, high-field (in situ) SABRE effects were generally not observed with the nanoscale catalysts. The potential for separation and reuse of such catalyst particles is also demonstrated. Taken together, these results support the potential utility of rational design at molecular, mesoscopic, and macroscopic/engineering levels for improving SABRE and HET-SABRE (heterogeneous-SABRE) for applications varying from fundamental studies of catalysis to biomedical imaging. PMID:26185545

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

NASA Astrophysics Data System (ADS)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell.

PubMed

Abdullah, M; Kamarudin, S K; Shyuan, L K

2016-12-01

In this study, TiO 2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm 2 (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

High-performance bimetallic alloy catalyst using Ni and N co-doped composite carbon for the oxygen electro-reduction.

PubMed

Jung, Won Suk

2018-03-15

In this study, a novel synthesis method for the bimetallic alloy catalyst is reported, which is subsequently used as an oxygen reduction catalyst in polymer electrolyte membrane fuel cells (PEMFCs). The support prepared from the Ni-chelate complex shows a mesoporous structure with a specific surface area of ca. 400 m 2  g -1 indicating the suitable support for PEMFC applications. Ethylenediamine is converted to the nitrogen and carbon layers to protect the Ni particles which will diffuse into the Pt lattice at 800 °C. The PtNi/NCC catalyst with PtNi cores and Pt-rich shells is successfully formed when acid-treated as evidenced by line scan profiles. The catalyst particles thus synthesized are well-dispersed on the N-doped carbon support, while the average particle size is ca. 3 nm. In the PEMFC test, the maximum power density of the PtNi/NCC catalyst shows approximately 25% higher than that of the commercial Pt/C catalyst. The mass activity of the PtNi/NCC catalyst showed approximately 3-fold higher than that of the commercial Pt/C catalyst. The mass activity strongly depends on the ratio of Pt to Ni since the strain effect can be strong for catalysts due to the mismatch of lattice parameters of the Ni and Pt. Copyright © 2017 Elsevier Inc. All rights reserved.

Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

NASA Astrophysics Data System (ADS)

Mikolajczuk-Zychora, A.; Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B.; Mazurkiewicz-Pawlicka, M.; Stobinski, L.; Ciecierska, E.; Zimoch, A.; Opałło, M.

2016-12-01

One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

Synthesis, characterization and evaluation of CO-oxidation catalysts for high repetition rate CO2 TEA lasers

NASA Technical Reports Server (NTRS)

Moser, Thomas P.

1990-01-01

An extremely active class of noble metal catalysts supported on titania was developed and fabricated at Hughes for the recombination of oxygen (O2) and carbon monoxide (CO) in closed-cycle CO2 TEA lasers. The incipient wetness technique was used to impregnate titania and alumina pellets with precious metals including platinum and palladium. In particular, the addition of cerium (used as an oxygen storage promoter) produced an extremely active Pt/Ce/TiO2 catalyst. By comparison, the complementary Pt/Ce/ gamma-Al2O3 catalyst was considerably less active. In general, chloride-free catalyst precursors proved critical in obtaining an active catalyst while also providing uniform metal distributions throughout the support structure. Detailed characterization of the Pt/Ce/TiO2 catalyst demonstrated uniform dendritic crystal growth of the metals throughout the support. Electron spectroscopy for Chemical Analysis (ESCA) analysis was used to characterize the oxidation states of Pt, Ce and Ti. The performance of the catalysts was evaluated with an integral flow reactor system incorporating real time analysis of O2 and CO. With this system, the transient and steady-state behavior of the catalysts were evaluated. The kinetic evaluation was complemented by tests in a compact, closed-cycle Hughes CO2 TEA laser operating at a pulse repetition rate of 100 Hz with a catalyst temperature of 75 to 95 C. The Pt/Ce/TiO2 catalyst was compatible with a C(13)O(16)2 gas fill.

Understanding the performance and mechanism of Mg-containing oxides as support catalysts in the thermal dry reforming of methane.

PubMed

Khairudin, Nor Fazila; Sukri, Mohd Farid Fahmi; Khavarian, Mehrnoush; Mohamed, Abdul Rahman

2018-01-01

Dry reforming of methane (DRM) is one of the more promising methods for syngas (synthetic gas) production and co-utilization of methane and carbon dioxide, which are the main greenhouse gases. Magnesium is commonly applied in a Ni-based catalyst in DRM to improve catalyst performance and inhibit carbon deposition. The aim of this review is to gain better insight into recent developments on the use of Mg as a support or promoter for DRM catalysts. Its high basicity and high thermal stability make Mg suitable for introduction into the highly endothermic reaction of DRM. The introduction of Mg as a support or promoter for Ni-based catalysts allows for good metal dispersion on the catalyst surface, which consequently facilitates high catalytic activity and low catalyst deactivation. The mechanism of DRM and carbon formation and reduction are reviewed. This work further explores how different constraints, such as the synthesis method, metal loading, pretreatment, and operating conditions, influence the dry reforming reactions and product yields. In this review, different strategies for enhancing catalytic activity and the effect of metal dispersion on Mg-containing oxide catalysts are highlighted.

Catalyst recycling via specific non-covalent adsorption on modified silicas.

PubMed

Kluwer, Alexander M; Simons, Chretien; Knijnenburg, Quinten; van der Vlugt, Jarl Ivar; de Bruin, Bas; Reek, Joost N H

2013-03-14

This article describes a new strategy for the recycling of a homogeneous hydroformylation catalyst, by selective adsorption of the catalyst to tailor-made supports after a batchwise reaction. The separation of the catalyst from the product mixture is based on selective non-covalent supramolecular interactions between a ligand and the support. Changing the solvent releases the active catalyst back into the reactor and allows a subsequent batch reaction with the recycled active catalyst. For this purpose, the bidentate NixantPhos ligand has been equipped with a pyridine group. The corresponding rhodium pre-catalyst [Rh(Nix-py)(acac)] (acac = acetylacetonate) forms a very selective, active and highly stable catalyst, and able to reach a turnover number (TON) of 170 000 in a single run (reaction performed in nearly neat 1-octene, S/C ratio of 200 000, at 140 °C, 20 bars syngas pressure). Various commercially available supports have been explored in binding studies and recycling experiments. The end-capped silica-alumina performs the best so far with respect to ligand-adsorbing properties for the current purpose. Although this system has not been fully optimized, four recycling runs could be performed successfully.

Understanding the performance and mechanism of Mg-containing oxides as support catalysts in the thermal dry reforming of methane

PubMed Central

Khairudin, Nor Fazila; Sukri, Mohd Farid Fahmi; Khavarian, Mehrnoush

2018-01-01

Dry reforming of methane (DRM) is one of the more promising methods for syngas (synthetic gas) production and co-utilization of methane and carbon dioxide, which are the main greenhouse gases. Magnesium is commonly applied in a Ni-based catalyst in DRM to improve catalyst performance and inhibit carbon deposition. The aim of this review is to gain better insight into recent developments on the use of Mg as a support or promoter for DRM catalysts. Its high basicity and high thermal stability make Mg suitable for introduction into the highly endothermic reaction of DRM. The introduction of Mg as a support or promoter for Ni-based catalysts allows for good metal dispersion on the catalyst surface, which consequently facilitates high catalytic activity and low catalyst deactivation. The mechanism of DRM and carbon formation and reduction are reviewed. This work further explores how different constraints, such as the synthesis method, metal loading, pretreatment, and operating conditions, influence the dry reforming reactions and product yields. In this review, different strategies for enhancing catalytic activity and the effect of metal dispersion on Mg-containing oxide catalysts are highlighted. PMID:29719767

Protonation of a lanthanum phosphide-alkyl occurs at the P-La not the C-La bond: isolation of a cationic lanthanum alkyl complex.

PubMed

Izod, Keith; Liddle, Stephen T; Clegg, William

2004-08-07

Protonation of the heteroleptic, cyclometalated lanthanum phosphide complex [((Me3Si)2CH)(C6H4-2-CH2NMe2)P]La(THF)[P(C6H4-2-CH2NMe2)(CH(SiMe3)(SiMe2CH2))] with [Et3NH][BPh4] yields the cationic alkyllanthanum complex [(THF)4La[P(C6H4-2-CH2NMe2)(CH(SiMe3)(SiMe2CH2))

Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

1987-01-01

Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

Thin film photovoltaic device

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1982-01-01

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Catalyst containing oxygen transport membrane

DOEpatents

Lane, Jonathan A.; Wilson, Jamie R.; Christie, Gervase Maxwell; Petigny, Nathalie; Sarantopoulos, Christos

2017-02-07

A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a microstructure exhibiting substantially uniform pore size distribution as a result of using PMMA pore forming materials or a bi-modal particle size distribution of the porous support layer materials. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

Corrosion-resistant catalyst supports for phosphoric acid fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kosek, J.A.; Cropley, C.C.; LaConti, A.B.

High-surface-area carbon blacks such as Vulcan XC-72 (Cabot Corp.) and graphitized carbon blacks such as 2700{degree}C heat-treated Black Pearls 2000 (HTBP) (Cabot Corp.) have found widespread applications as catalyst supports in phosphoric acid fuel cells (PAFCs). However, due to the operating temperatures and pressures being utilized in PAFCs currently under development, the carbon-based cathode catalyst supports suffer from corrosion, which decreases the performance and life span of a PAFC stack. The feasibility of using alternative, low-cost, corrosion-resistant catalyst support (CRCS) materials as replacements for the cathode carbon support materials was investigated. The objectives of the program were to prepare high-surface-areamore » alternative supports and to evaluate the physical characteristics and the electrochemical stability of these materials. The O{sub 2} reduction activity of the platinized CRCS materials was also evaluated. 2 refs., 3 figs.« less

Nitrogen-doped three-dimensional graphene-supported platinum catalysts for polymer electrolyte membrane fuel cells application

NASA Astrophysics Data System (ADS)

Chu, Fuqiang; Li, Xingxing; Yuan, Wensen; Zhu, Huanhuan; Qin, Yong; Zhang, Shuai; Yuan, Ningyi; Lin, Bencai; Ding, Jianning

Catalysts are a key component of polymer electrolyte membrane fuel cells (PEMFCs). In this work, nitrogen-doped three-dimensional graphene-supported platinum (Pt-3DNG) catalysts are successfully prepared and characterized. SEM and TEM images show the Pt nanoparticles are uniformly dispersed in the sheets of nitrogen-doped 3DNG. Compared with that of the commercial Pt/C catalysts, Pt-3DNG show much better oxygen reduction reaction (ORR) activity and cycling stability, and the reduction in limit current density after 1000 cycles is only about 1.6% for the Pt-3DNG catalysts, whereas 7.2% for the commercial Pt/C catalysts. The single cell using Pt-3DNG catalysts in both the anode and the cathode show a higher peak power density (21.47mW cm-2) than that using commercial Pt/C catalysts (20.17mW cm-2) under the same conditions. These properties make this type of catalyst suitable for the application in PEMFCs.

Static and dynamic structural characterization of nanomaterial catalysts

NASA Astrophysics Data System (ADS)

Masiel, Daniel Joseph

Heterogeneous catalysts systems are pervasive in industry, technology and academia. These systems often involve nanostructured transition metal particles that have crucial interfaces with either their supports or solid products. Understanding the nature of these interfaces as well as the structure of the catalysts and support materials themselves is crucial for the advancement of catalysis in general. Recent developments in the field of transmission electron microscopy (TEM) including dynamic transmission electron microscopy (DTEM), electron tomography, and in situ techniques stand poised to provide fresh insight into nanostructured catalyst systems. Several electron microscopy techniques are applied in this study to elucidate the mechanism of silica nanocoil growth and to discern the role of the support material and catalyst size in carbon dioxide and steam reforming of methane. The growth of silica nanocoils by faceted cobalt nanoparticles is a process that was initially believed to take place via a vapor-liquid-solid growth mechanism similar to other nanowire growth techniques. The extensive TEM work described here suggests that the process may instead occur via transport of silicate and silica species over the nanoparticle surface. Electron tomography studies of the interface between the catalyst particles and the wire indicate that they grow from edges between facets. Studies on reduction of the Co 3O4 nanoparticle precursors to the faceted pure cobalt catalysts were carried out using DTEM and in situ heating. Supported catalyst systems for methane reforming were studied using dark field scanning TEM to better understand sintering effects and the increased activity of Ni/Co catalysts supported by carbon nanotubes. Several novel electron microscopy techniques are described including annular dark field DTEM and a metaheuristic algorithm for solving the phase problem of coherent diffractive imaging. By inserting an annular dark field aperture into the back focal plane of the objective lens in a DTEM, time-resolved dark field images can be produced that have vastly improved contrast for supported catalyst materials compared to bright field DTEM imaging. A new algorithm called swarm optimized phase retrieval is described that uses a population-based approach to solve for the missing phases of diffraction data from discrete particles.

Pd nanoparticles Supported on Cellulose as a catalyst for vanillin conversion in aqueous media.

PubMed

Li, Dan-Dan; Zhang, Jia-Wei; Cai, Chun

2018-05-17

Palladium nanoparticles were firstly anchored on modified biopolymer as an efficient catalyst for biofuel upgradation. Fluorinated compounds was grafted onto cellulose to obtain amphiphilic supports for on water reactions. Pd catalyst was prepared by straightforward deposition of metal nanoparticles on modified cellulose. The catalyst exhibited excellent catalytic activity and selectivity in hydrodeoxygenation of vanillin (a typical model compound of lignin) to 2-methoxy-4-methylphenol under atmospheric hydrogen pressure in neat water without any other additives under mild conditions.

Synthesis and Characterization of Polyethylene/Starch Nanocomposites: A Spherical Starch-Supported Catalyst and In Situ Ethylene Polymerization.

PubMed

Zhanga, Hao; Xi, Shixia; Wang, Shuwei; Liu, Jingsheng; Yoon, Keun-Byoung; Lee, Dong-Ho; Zhang, Hexin; Zhang, Xuequan

2017-01-01

In the present article, a novel spherical starch-supported vanadium (V)-based Ziegler-Natta catalyst was synthesized. The active centers of the obtained catalyst well dispersed in the starch through the SEM-EDX analysis. The effects of reaction conditions on ethylene polymerization were studied. The synthesized catalyst exhibited high activity toward ethylene polymerization in the presence of ethylaluminium sesquichloride (EASC) cocatalyst. Interestingly, the fiber shape PE was obtained directly during the polymerization process.

Catalyst, method of making, and reactions using the catalyst

DOEpatents

Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

2009-03-03

The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

Catalyst, method of making, and reactions using the catalyst

DOEpatents

Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

2002-08-27

The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

Catalyst, Method Of Making, And Reactions Using The Catalyst

DOEpatents

Tonkovich, Anna Lee Y.; Wang, Yong; Gao, Yufei

2004-07-13

The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

Doped palladium containing oxidation catalysts

DOEpatents

Mohajeri, Nahid

2014-02-18

A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

Hydrogenation of succinic acid to 1,4-butanediol over rhenium catalyst supported on copper-containing mesoporous carbon.

PubMed

Hong, Ung Gi; Park, Hai Woong; Lee, Joongwon; Hwang, Sunhwan; Kwak, Jimin; Yi, Jongheop; Song, In Kyu

2013-11-01

Copper-containing mesoporous carbon (Cu-MC) was prepared by a single-step surfactant-templating method. For comparison, copper-impregnated mesoporous carbon (Cu/MC) was also prepared by a surfactant-templating method and a subsequent impregnation method. Rhenium catalysts supported on copper-containing mesoporous carbon and copper-impregnated mesoporous carbon (Re/Cu-MC and Re/Cu/MC, respectively) were then prepared by an incipient wetness method, and they were applied to the liquid-phase hydrogenation of succinic acid to 1,4-butanediol (BDO). It was observed that copper in the Re/Cu-MC catalyst was well incorporated into carbon framework, resulting in higher surface area and larger pore volume than those of Re/Cu/MC catalyst. Therefore, Re/Cu-MC catalyst showed higher copper dispersion than Re/Cu/MC catalyst, although both catalysts retained the same amounts of copper and rhenium. In the liquid-phase hydrogenation of succinic acid to BDO, Re/Cu-MC catalyst showed a better catalytic activity than Re/Cu/MC catalyst. Fine dispersion of copper in the Re/Cu-MC catalyst was responsible for its enhanced catalytic activity.

Influence of various carbon nano-forms as supports for Pt catalyst on proton exchange membrane fuel cell performance

NASA Astrophysics Data System (ADS)

Bharti, Abha; Cheruvally, Gouri

2017-08-01

In this study, we discuss the influence of various carbon supports for Pt on proton exchange membrane (PEM) fuel cell performance. Here, Pt supported on various carbon nano-forms [Pt/carbon black (Pt/CB), Pt/single-walled carbon nanotubes (Pt/SWCNT), Pt/multi-walled carbon nanotubes (Pt/MWCNT) and Pt/graphene (Pt/G)] are synthesized by a facile, single step, microwave-assisted, modified chemical reduction route. Their physical, chemical and electrochemical characteristics pertaining to oxygen reduction reaction (ORR) catalytic activity and stability in PEM fuel cell are studied in detail by various techniques and compared. The study shows that the different carbon supports does not significantly affect the Pt particle size during synthesis, but leads to different amount of defective sites in the carbon framework which influence both the availability of active metal nano-catalysts and metal-support interaction. In-situ electrochemical investigations reveal that the different carbon supports influence both ORR catalytic activity and stability of the catalyst. This is further corroborated by the demonstration of varying polarization characteristics on PEM fuel cell performance by different carbon supported Pt catalysts. This study reveals MWCNT as the most suitable carbon support for Pt catalyst, exhibiting high activity and stability for ORR in PEM fuel cell.

Atomic level study of water-gas shift catalysts via transmission electron microscopy and x-ray spectroscopy

NASA Astrophysics Data System (ADS)

Akatay, Mehmed Cem

Water-gas shift (WGS), CO + H2O ⇆ CO2 + H2 (DeltaH° = -41 kJ mol -1), is an industrially important reaction for the production of high purity hydrogen. Commercial Cu/ZnO/Al2O3 catalysts are employed to accelerate this reaction, yet these catalysts suffer from certain drawbacks, including costly regeneration processes and sulfur poisoning. Extensive research is focused on developing new catalysts to replace the current technology. Supported noble metals stand out as promising candidates, yet comprise intricate nanostructures complicating the understanding of their working mechanism. In this study, the structure of the supported Pt catalysts is explored by transmission electron microscopy and X-ray spectroscopy. The effect of the supporting phase and the use of secondary metals on the reaction kinetics is investigated. Structural heterogeneities are quantified and correlated with the kinetic descriptors of the catalysts to develop a fundamental understanding of the catalytic mechanism. The effect of the reaction environment on catalyst structure is examined by in-situ techniques. This study benefitted greatly from the use of model catalysts that provide a convenient medium for the atomic level characterization of nanostructures. Based on these studies, Pt supported on iron oxide nano islands deposited on inert spherical alumina exhibited 48 times higher WGS turnover rate (normalized by the total Pt surface area) than Pt supported on bulk iron oxide. The rate of aqueous phase glycerol reforming reaction of Pt supported on multiwall carbon nanotubes (MWCNT) is promoted by co-impregnating with cobalt. The synthesis resulted in a variety of nanostructures among which Pt-Co bimetallic nanoparticles are found to be responsible for the observed promotion. The unprecedented WGS rate of Pt supported on Mo2C is explored by forming Mo 2C patches on top of MWCNTs and the rate promotion is found to be caused by the Pt-Mo bimetallic entities.

Oxidative coupling of methane over SrO deposited on different commercial supports precoated with La{sub 2}O{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, V.R.; Mulla, S.A.R.; Uphade, B.S.

1998-06-01

The influence of catalyst carrier or support (with different chemical compositions and surface properties), catalyst deposition method (viz., impregnation and coating), precursor for strontium oxide (SrO; Sr-nitrate, acetate, hydroxide, and carbonate), and loading of SrO and lanthanum oxide (La{sub 2}O{sub 3}; 0--25 wt%) on the surface properties and performance of catalyst in oxidative coupling of methane (OCM; at 850 C, gas hourly space velocity = 1.02 {times} 10{sup 5} cm{sup 3}/g{center_dot}h and CH{sub 4}/O{sub 2} = 4 or 16) was thoroughly investigated. The basicity, acidity, and O{sub 2} chemisorption of the catalysts were studied by the temperature programmed desorption (TPD)more » of CO{sub 2}, NH{sub 3}, and O{sub 2}, respectively, from 50 to 950 C. The total and strong basic sites, acidity, and OCM activity of the supported catalyst were strongly influenced by the support used and also by the La{sub 2}O{sub 3} loading on the support. The catalyst with a sintered low surface area porous silica-Alumina support and high (20 wt%) La{sub 2}O{sub 3} and SrO loadings showed the best performance in the OCM process. The OCM activity was influenced by SrO loading, but to a smaller extent, and also by the method of SrO deposition. The OCM activity of the supported catalysts could be related to their strong basic sites (measured in terms of the CO{sub 2} desorbed between 500 and 950 C).« less

Synthesis, characterization, and activity of Co/Fe alumina/silica supported Ft catalysts and the study of promoter effect of ruthenium

NASA Astrophysics Data System (ADS)

Esumike, Sunday Azubike

The alumina and hybrid alumina-silica FT catalyst were prepared by one-step solgel/oil-drop methods using metal-nitrate-solutions (method-I), and nanoparticle-metaloxides (method-2). The nanoparticle-metal-oxides did not participate in solubility equilibria in contrast to metal nitrate in method-1 causing no metal ion seepage; therefore, method-2 yields higher XRF metal loading efficiency than method-1. The thermal analysis confirmed that the metal loading by method-1 and method-2 involved two different pathways. Method-1 involves solubility equilibria in the conversion of metal-nitrate to metal- hydroxide and finally to metal-oxide, while in method-2 nanoparticle-metal-oxide remained intact during sol-gel-oil-drop and calcination steps. The alumina supported catalysts were dominated by gamma-alumina PXRD peaks in alumina catalysts while amorphous alumino-silicate phase was the bulk of hybrid alumina-silica catalysts. The presence of cobalt oxides (CoO, Co3O4) and iron oxides (FeO, Fe2O3) phases are confirmed in the catalysts prepared by method-1 and method-2. The PXRD analysis indicated weak peak intensities in catalysts with 5 wt. % total metal loading. PXRD pattern confirmed alloy formation in the bimetallic catalysts (CoFe2O4) on alumina support phase gamma-A12 O3. The surface area and pore diameter of hybrid alumina-silica granules (301 - 372 m2/g and 7.3 nm) showed better values than the alumina granules (251 - 256 m2/g and 6.5 nm). The support pore diameter of both types of granules is within the mesoporous range (1 - 50 nm). The morphology of all the catalysts is preserved upon metal loading and heat treatments. The surface characteristics of the sol-gel-oil-drop method prepared catalysts indicate there was no significant pore blockage of the support below 10 wt % total metal loading. The CO conversion of the FT catalysts was measured to screen catalytic active metals and determine the optimum temperatures of the FT reaction for the alumina catalysts. The alumina FT catalysts showed an optimum reaction temperature of 250 °C. Hydrocarbon production and CO conversion of alumina and hybrid alumina-silica FT catalysts were investigated. Among monometallic alumina catalysts, Co(5%) showed a higher CO conversion. The incorporation of Fe to Co increased CO conversion and hydrocarbon production. Increased Fe content in the bimetallic catalysts prepared by combined method-1&2, decreased CO conversion and hydrocarbon production, and increased CO 2 production. The bimetallic nano-Co(2.5%)nano-Fe(2.5%) prepared by method-2 alone showed higher CO conversion comparable to the Co(4%)nano-Fe(l %). Hybrid alumina-silica FT catalysts showed a higher CO conversion than the alumina FT catalysts due to better surface characteristics. The monometallic catalysts showed higher selectivity to C1-C4 hydrocarbon than bimetallic. The bimetallic alumina FT catalysts prepared by method-2 showed slightly higher C5+ selectivity compared to the higher Co catalysts prepared by combined method- I &2. The Ru promotion showed a significant effect on the CO conversion and 11 product distribution of the monometallic catalysts. There was no significant effect on the CO conversion on the (Co-Fe) bimetallic catalysts, but hydrocarbon production slightly increased when promoted by 0.5 wt.% Ru.

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

DOE PAGES

Islam, A. E.; Zakharov, D.; Stach, E. A.; ...

2015-09-16

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only inmore » the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.« less

Comparative study of different carbon-supported Fe2O3-Pt catalysts for oxygen reduction reaction.

PubMed

Tellez-Cruz, M M; Padilla-Islas, M A; Pérez-González, M; Solorza-Feria, O

2017-11-01

One of the challenges in electrocatalysis is the adequate dispersion of the catalyst on an appropriate porous support matrix, being up to now the most commonly used the carbon-based supports. To overcome this challenge, carbon supports must first be functionalized to guide the catalyst's nucleation, thereby, improving the dispersion and allowing the use of smaller amount of the catalyst material to achieve a higher electrochemically active surface area. This study present the effect of functionalized Vulcan carbon XC72 (FVC) and functionalized Black Pearl carbon (FBPC) as supports on the catalytic activity of decorated Fe 2 O 3 with Pt. Both carbons were functionalized with HNO 3 and subsequently treated with ethanolamine. Fe 2 O 3 nanoparticles were synthesized by chemical reduction and decorated with platinum by epitaxial growth. Pt and Fe 2 O 3 structural phases were identified by XRD and XPS; the Pt content was measured by XPS, and results showed to a high Pt content in Fe 2 O 3 -Pt/FBPC. TEM micrographs reveal nanoparticles with an average size of 2 nm in both supported catalysts. The Fe 2 O 3 -Pt/FVC catalyst presents the highest specific activity and mass activity, 0.21 mA cm -2 Pt and 140 mA mg Pt -1 , respectively, associated to the appropriate distribution of platinum on the Fe 2 O 3 nanoparticles.

Carbon nanotube synthesis with different support materials and catalysts

NASA Astrophysics Data System (ADS)

Gümüş, Fatih; Yuca, Neslihan; Karatepe, Nilgün

2013-09-01

Having remarkable characteristics, carbon nanotubes (CNTs) have attracted a lot of interest. Their mechanical, electrical, thermal and chemical properties make CNTs suitable for several applications such as electronic devices, hydrogen storage, textile, drug delivery etc. CNTs have been synthesized by various methods, such as arc discharge, laser ablation and catalytic chemical vapor deposition (CCVD). In comparison with the other techniques, CCVD is widely used as it offers a promising route for mass production. High capability of decomposing hydrocarbon formation is desired for the selected catalysts. Therefore, transition metals which are in the nanometer scale are the most effective catalysts. The common transition metals that are being used are Fe, Co, Ni and their binary alloys. The impregnation of the catalysts over the support material has a crucial importance for the CNT production. In this study, the influence of the support materials on the catalytic activity of metals was investigated. CNTs have been synthesized over alumina (Al2O3), silica (SiO2) and magnesium oxide (MgO) supported Fe, Co, Fe-Co catalysts. Catalyst - support material combinations have been investigated and optimum values for each were compared. Single walled carbon nanotubes (SWCNTs) were produced at 800°C. The duration of synthesis was 30 minutes for all support materials. The synthesized materials were characterized by thermal gravimetric analysis (TGA), Raman spectroscopy and transmission electron microscopy.

Ferric hydroxide supported gold subnano clusters or quantum dots: enhanced catalytic performance in chemoselective hydrogenation.

PubMed

Liu, Lequan; Qiao, Botao; Ma, Yubo; Zhang, Juan; Deng, Youquan

2008-05-21

An attempt to prepare ferric hydroxide supported Au subnano clusters via modified co-precipitation without any calcination was made. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been employed to study the structure and chemical states of these catalysts. No Au species could be observed in the HRTEM image nor from the XRD pattern, suggesting that the sizes of the Au species in and on the ferric hydroxide support were less than or around 1 nm. Chemoselective hydrogenation of aromatic nitro compounds and alpha,beta-unsaturated aldehydes was selected as a probe reaction to examine the catalytic properties of this catalyst. Under the same reaction conditions, such as 100 degrees C and 1 MPa H2 in the hydrogenation of aromatic nitro compounds, a 96-99% conversion (except for 4-nitrobenzonitrile) with 99% selectivity was obtained over the ferric hydroxide supported Au catalyst, and the TOF values were 2-6 times higher than that of the corresponding ferric oxide supported catalyst with 3-5 nm size Au particles. For further evaluation of this Au catalyst in the hydrogenation of citral and cinnamaldehyde, selectivity towards unsaturated alcohols was 2-20 times higher than that of the corresponding ferric oxide Au catalyst.

Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers

PubMed Central

Calderón, Juan Carlos; Rios Ráfales, Miguel; Nieto-Monge, María Jesús; Pardo, Juan Ignacio; Moliner, Rafael; Lázaro, María Jesús

2016-01-01

In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding—as a rate determining step—the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies. PMID:28335315

Subnanometer and nanometer catalysts, method for preparing size-selected catalysts

DOEpatents

Vajda, Stefan , Pellin, Michael J.; Elam, Jeffrey W [Elmhurst, IL; Marshall, Christopher L [Naperville, IL; Winans, Randall A [Downers Grove, IL; Meiwes-Broer, Karl-Heinz [Roggentin, GR

2012-04-03

Highly uniform cluster based nanocatalysts supported on technologically relevant supports were synthesized for reactions of top industrial relevance. The Pt-cluster based catalysts outperformed the very best reported ODHP catalyst in both activity (by up to two orders of magnitude higher turn-over frequencies) and in selectivity. The results clearly demonstrate that highly dispersed ultra-small Pt clusters precisely localized on high-surface area supports can lead to affordable new catalysts for highly efficient and economic propene production, including considerably simplified separation of the final product. The combined GISAXS-mass spectrometry provides an excellent tool to monitor the evolution of size and shape of nanocatalyst at action under realistic conditions. Also provided are sub-nanometer gold and sub-nanometer to few nm size-selected silver catalysts which possess size dependent tunable catalytic properties in the epoxidation of alkenes. Invented size-selected cluster deposition provides a unique tool to tune material properties by atom-by-atom fashion, which can be stabilized by protective overcoats.

Subnanometer and nanometer catalysts, method for preparing size-selected catalysts

DOEpatents

Vajda, Stefan [Lisle, IL; Pellin, Michael J [Naperville, IL; Elam, Jeffrey W [Elmhurst, IL; Marshall, Christopher L [Naperville, IL; Winans, Randall A [Downers Grove, IL; Meiwes-Broer, Karl-Heinz [Roggentin, GR

2012-03-27

Highly uniform cluster based nanocatalysts supported on technologically relevant supports were synthesized for reactions of top industrial relevance. The Pt-cluster based catalysts outperformed the very best reported ODHP catalyst in both activity (by up to two orders of magnitude higher turn-over frequencies) and in selectivity. The results clearly demonstrate that highly dispersed ultra-small Pt clusters precisely localized on high-surface area supports can lead to affordable new catalysts for highly efficient and economic propene production, including considerably simplified separation of the final product. The combined GISAXS-mass spectrometry provides an excellent tool to monitor the evolution of size and shape of nanocatalyst at action under realistic conditions. Also provided are sub-nanometer gold and sub-nanometer to few nm size-selected silver catalysts which possess size dependent tunable catalytic properties in the epoxidation of alkenes. Invented size-selected cluster deposition provides a unique tool to tune material properties by atom-by-atom fashion, which can be stabilized by protective overcoats.

A new chitosan Schiff base supported Pd(II) complex for microwave-assisted synthesis of biaryls compounds

NASA Astrophysics Data System (ADS)

Baran, Talat

2017-08-01

In this study, a new heterogeneous palladium (II) catalyst that contains O-carboxymethyl chitosan Schiff base has been designed for Suzuki coupling reactions. The chemical structures of the synthesized catalyst were characterized with the FTIR, TG/DTG, ICP-OES, SEM/EDAX, 1H NMR, 13C NMR, GC/MS, XRD, and magnetic moment techniques. The reusability and catalytic behavior of heterogeneous catalyst was tested towards Suzuki reactions. As a result of the tests, excellent selectivity was obtained, and by-products of homo coupling were not seen in the spectra. The biaryls products were identified on a GC/MS. In addition, it was determined in the reusability tests that the catalysts could be used several times (seven runs). More importantly, with very low catalyst loading (6 × 10-3 mol %) in very short reaction time (5 min), chitosan Schiff base supported Pd(II) complex gave high TON and TOF values. These findings showed that Schiff base supported Pd(II) catalyst is suitable for Suzuki cross coupling reactions.

Highly porous non-precious bimetallic electrocatalysts for efficient hydrogen evolution

DOE PAGES

Lu, Qi; Hutchings, Gregory S.; Yu, Weiting; ...

2015-03-16

One of the key components of carbon dioxide-free hydrogen production is a robust and efficient non-precious metal catalyst for the hydrogen evolution reaction. We report that a hierarchical nanoporous copper-titanium bimetallic electrocatalyst is able to produce hydrogen from water under a mild overpotential at more than twice the rate of state-of-the- art carbon-supported platinum catalyst. Although both copper and titanium are known to be poor hydrogen evolution catalysts, the combination of these two elements creates unique copper-copper-titanium hollow sites, which have a hydrogen-binding energy very similar to that of platinum, resulting in an exceptional hydrogen evolution activity. Moreover, the hierarchicalmore » porosity of the nanoporous-copper titanium catalyst also contributes to its high hydrogen evolution activity, because it provides a large-surface area for electrocatalytic hydrogen evolution, and improves the mass transport properties. Moreover, the catalyst is self-supported, eliminating the overpotential associated with the catalyst/support interface.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Sol; Thornburg, Nicholas E.; Li, Zhanyong

In this study by developing structurally well-defined, supported oxide catalysts remains a significant challenge. Here, we report the grafting of Nb(V) oxide sites onto the nodes of the Zr-based metal organic framework (MOF) NU-1000 as a stable, well-defined catalyst support. Nb(V) oxide was deposited with loadings up to 1.6 mmol/g via two post-synthetic methods: atomic layer deposition in a MOF (AIM), and solution-phase grafting in a MOF (SIM). Difference envelope density (DED) measurements indicated that the two synthetic methods resulted in different local structures of the Nb(V) ions within NU-1000. Despite their high Nb(V) loadings, which were equivalent to >60%more » surface coverage, nearly all Nb(V) sites of the MOF-supported catalysts were active sites for alkene epoxidation, as confirmed by phenylphosphonic acid titration. The MOF-supported catalysts were more selective than the control Nb-ZrO 2 catalyst for cyclohexene epoxidation with aqueous H 2O 2, and were far more active on a gravimetric basis.« less

Carbon nanocages: A new support material for Pt catalyst with remarkably high durability

PubMed Central

Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

2014-01-01

Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for “real world” application. PMID:24658614

Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

DOE PAGES

Zhuang, Zhongbin; Giles, Stephen A.; Zheng, Jie; ...

2016-01-14

The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizesmore » the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Here, owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.« less

Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte

PubMed Central

Zhuang, Zhongbin; Giles, Stephen A.; Zheng, Jie; Jenness, Glen R.; Caratzoulas, Stavros; Vlachos, Dionisios G.; Yan, Yushan

2016-01-01

The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells. PMID:26762466

RuO2 supported NaY zeolite catalysts: Effect of preparation methods on catalytic performance during aerobic oxidation of benzyl alcohol

NASA Astrophysics Data System (ADS)

Jung, Dasom; Lee, Sunwoo; Na, Kyungsu

2017-10-01

The effects of preparation method for RuO2 supported zeolite catalysts on the catalytic consequences during the aerobic oxidation of benzyl alcohol to benzaldehyde were investigated. Three preparation methods, i.e., (i) simultaneous crystallization of the zeolite framework in the presence of RuCl3 (Ru(SC)/NaY), (ii) post ion-exchange with RuCl3 on the zeolite framework (Ru(IE)/NaY), and (iii) post support of preformed Ru metal nanoparticles on the zeolite surface (Ru(PS)/NaY), were used to construct three different RuO2 supported NaY zeolite catalysts. The catalyst performance was investigated as functions of the reaction time and temperature, in correlation with the structural changes of the catalysts, as analyzed by X-ray diffraction (XRD). The results revealed that the catalytic consequences were dramatically affected by the preparation methods. Although similar conversion was achieved with all three catalysts, the turnover frequency (TOF) differed. The Ru(PS)/NaY catalyst exhibited the highest TOF (33-48 h-1), whereas the other catalysts produced much lower TOFs (9-12 h-1). The Ru(PS)/NaY catalyst also had the highest activation energy (Ea) of 48.39 kJ mol-1, whereas the Ru(SC)/NaY and Ru(IE)/NaY catalysts had Ea values of 18.58 and 24.11 kJ mol-1, respectively. Notably, the Ru(PS)/NaY catalyst yielded a significantly higher pre-exponential factor of 5.22 × 105 h-1, which is about 5 orders of magnitude larger than that of the Ru(SC)/NaY catalyst (7.15 × 100 h-1). This suggests that collision between benzyl alcohol and molecular oxygen was very intensive on the Ru(PS)/NaY catalyst, which explains the higher TOF of the Ru(PS)/NaY catalyst relative to the others in spite of the higher Ea value of the former. In terms of recyclability, the pristine crystallinity of the zeolite framework was maintained in the Ru(SC)/NaY catalyst and the RuO2 phase exhibited an insignificant loss of the initial activity up to three catalytic cycles, whereas Ru(PS)/NaY showed slight loss of activity and Ru(IE)/NaY showed a significant loss of activity due to the disappearance of the RuO2 phase.

Impact of support calcination and competitive adsorbate in Fe/Mo-Al2O3 catalyst for synthesis of carbon nanotubes by V-flame

NASA Astrophysics Data System (ADS)

Sun, Ya-Ping; Sun, Bao-Min; Zhai, Gang; Guo, Yong-Hong; Jia, Xiao-Wei; Kang, Zhi-Zhong

2018-05-01

Carbon nanotubes (CNTs) were synthesized via carbon monoxide decomposition with aid of various Fe/Mo-Al2O3 catalysts by V-type flame method. The influences of support calcination and competitive adsorbates on the morphology and properties of CNTs were studied. SEM, HRTEM, TPO and Raman spectroscopy were applied to investigate the morphology and microstructure of CNT products. XRD, H2-TPR were employed to characterize catalysts. The obtained results indicate that calcinated support can increase production and promote the formation of CNTs with small diameter. Utilizing citric acid as a competitive adsorbate is successful in improving the quality of CNTs. Besides, the addition of citric acid and calcinated support in catalyst enhances the catalytic growth activity. The obtained CNTs have a diameter around 4–6 nm within a narrow diameter distribution range. Raman spectrum analysis also illustrates that highly graphitized CNTs are produced on the catalyst with calcinated support and citric acid. These results suggest that support calcination and competitive adsorbate have pronounced effect on the average diameter, diameter distribution, and graphitization of CNTs, which provides a simple and effective way to tune the properties of CNTs.

3D polymer hydrogel for high-performance atomic iron-rich catalysts for oxygen reduction in acidic media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Zhi; Zhang, Hanguang; Karakalos, Stavros

Current platinum group metal (PGM)-free carbon nanocomposite catalysts for the oxygen reduction reaction (ORR) in acidic electrolyte often suffer from rapid degradation associated with carbon corrosion due to the use of large amount of amorphoous carbon black supports. Here, we developed a new concept of using freestanding 3D hydrogel to design support-free Fe-N-C catalysts. A 3D polyaniline (PANI)-based hydrogel was used for preparing a new type of single atomic iron site-rich catalyst, which has exhibited exceptionally enhanced activity and stability compared to conventional Fe-N-C catalysts supported on amorphous carbon blacks. The achieved performance metric on the hydrogel PANI-Fe catalysts ismore » one of the best ever reported PGM-free catalysts, reaching a half-wave potential up to 0.83 V vs. RHE and only leaving 30 mV gap with Pt/C catalysts (60 μgPt/cm2) in challenging acidic media. Remarkable ORR stability was accomplished as well on the same catalyst evidenced by using harsh potential cycling tests. The well dispersion of atomic iron into partially graphitized carbon, featured with dominance of micropores and porous network structures, is capable of accommodating increased number of active sites, strengthening local bonding among iron, nitrogen and carbon, and facilitating mass transfer. The 3D polymer hydrogel approach would be a new pathway to advance PGM-free catalysts.« less

3D polymer hydrogel for high-performance atomic iron-rich catalysts for oxygen reduction in acidic media

DOE PAGES

Qiao, Zhi; Zhang, Hanguang; Karakalos, Stavros; ...

2017-08-03

Current platinum group metal (PGM)-free carbon nanocomposite catalysts for the oxygen reduction reaction (ORR) in acidic electrolyte often suffer from rapid degradation associated with carbon corrosion due to the use of large amount of amorphoous carbon black supports. Here, we developed a new concept of using freestanding 3D hydrogel to design support-free Fe-N-C catalysts. A 3D polyaniline (PANI)-based hydrogel was used for preparing a new type of single atomic iron site-rich catalyst, which has exhibited exceptionally enhanced activity and stability compared to conventional Fe-N-C catalysts supported on amorphous carbon blacks. The achieved performance metric on the hydrogel PANI-Fe catalysts ismore » one of the best ever reported PGM-free catalysts, reaching a half-wave potential up to 0.83 V vs. RHE and only leaving 30 mV gap with Pt/C catalysts (60 μgPt/cm2) in challenging acidic media. Remarkable ORR stability was accomplished as well on the same catalyst evidenced by using harsh potential cycling tests. The well dispersion of atomic iron into partially graphitized carbon, featured with dominance of micropores and porous network structures, is capable of accommodating increased number of active sites, strengthening local bonding among iron, nitrogen and carbon, and facilitating mass transfer. The 3D polymer hydrogel approach would be a new pathway to advance PGM-free catalysts.« less

Method of Heating a Foam-Based Catalyst Bed

NASA Technical Reports Server (NTRS)

Fortini, Arthur J.; Williams, Brian E.; McNeal, Shawn R.

2009-01-01

A method of heating a foam-based catalyst bed has been developed using silicon carbide as the catalyst support due to its readily accessible, high surface area that is oxidation-resistant and is electrically conductive. The foam support may be resistively heated by passing an electric current through it. This allows the catalyst bed to be heated directly, requiring less power to reach the desired temperature more quickly. Designed for heterogeneous catalysis, the method can be used by the petrochemical, chemical processing, and power-generating industries, as well as automotive catalytic converters. Catalyst beds must be heated to a light-off temperature before they catalyze the desired reactions. This typically is done by heating the assembly that contains the catalyst bed, which results in much of the power being wasted and/or lost to the surrounding environment. The catalyst bed is heated indirectly, thus requiring excessive power. With the electrically heated catalyst bed, virtually all of the power is used to heat the support, and only a small fraction is lost to the surroundings. Although the light-off temperature of most catalysts is only a few hundred degrees Celsius, the electrically heated foam is able to achieve temperatures of 1,200 C. Lower temperatures are achievable by supplying less electrical power to the foam. Furthermore, because of the foam s open-cell structure, the catalyst can be applied either directly to the foam ligaments or in the form of a catalyst- containing washcoat. This innovation would be very useful for heterogeneous catalysis where elevated temperatures are needed to drive the reaction.

Special Issue in Honor of Professor S. Ted Oyama: 2014 ACS Distinguished Researcher Award in Petroleum Chemistry and Storch Award in Fuel Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bravo-Suárez, Juan J.; Wang, Xianqin; Li, Wei

This special issue of Topics in Catalysis honors Professor S. Ted Oyama for his Awards in Petroleum Chemistry and Fuel Science Research. These awards were celebrated at two American Chemical Society (ACS) symposia in 2014. First, the ACS’s Distinguished Research Award in Petroleum Chemistry Symposium, took place at the 247th ACS National Meeting in Dallas, TX, during March 17-19, 2014 and the second one, the ACS’s Storch Award in Fuel Science Symposium, took place at the 248th ACS National Meeting in San Francisco, CA, during August 10-12, 2014. Professor Oyama received the 2014 ACS Distinguished Research Award in Petroleum Chemistrymore » ‘‘for his substantial contributions to the field of heterogeneous catalysis’’ including the discovery of highly active transition metal phosphide catalysts for hydrotreatment of petroleum and coal-derived feedstocks and biomass refining, the development of new compositions, and the understanding of their reaction mechanisms by in situ spectroscopic techniques at high temperatures and pressures of reaction. In light of this recognition, Professor Oyama was also awarded the 2014 ACS Storch Award in Fuel Science ‘‘for his broad contributions to the field of fuel science’’ including the production of hydrogen by catalytic reforming, selective oxidation of hydrocarbons, biomass conversion, their reaction kinetics and mechanisms, and spectrokinetic methods to study catalysts in situ at reaction conditions and theory and application of inorganic membranes for separation of hydrogen and fuel-relevant gases. Finally, this special issue consists of contributions by catalysis researchers who participated in the two ACS symposia honoring Professor Oyama’s Awards.« less

Steam reforming of fuel to hydrogen in fuel cells

DOEpatents

Fraioli, Anthony V.; Young, John E.

1984-01-01

A fuel cell capable of utilizing a hydrocarbon such as methane as fuel and having an internal dual catalyst system within the anode zone, the dual catalyst system including an anode catalyst supporting and in heat conducting relationship with a reforming catalyst with heat for the reforming reaction being supplied by the reaction at the anode catalyst.

Towards the Rational Design of Nanoparticle Catalysts

NASA Astrophysics Data System (ADS)

Dash, Priyabrat

This research is focused on development of routes towards the rational design of nanoparticle catalysts. Primarily, it is focused on two main projects; (1) the use of imidazolium-based ionic liquids (ILs) as greener media for the design of quasi-homogeneous nanoparticle catalysts and (2) the rational design of heterogeneous-supported nanoparticle catalysts from structured nanoparticle precursors. Each project has different studies associated with the main objective of the design of nanoparticle catalysts. In the first project, imidazolium-based ionic liquids have been used for the synthesis of nanoparticle catalysts. In particular, studies on recyclability, reuse, mode-of-stability, and long-term stability of these ionic-liquid supported nanoparticle catalysts have been done; all of which are important factors in determining the overall "greenness" of such synthetic routes. Three papers have been published/submitted for this project. In the first publication, highly stable polymer-stabilized Au, Pd and bimetallic Au-Pd nanoparticle catalysts have been synthesized in imidazolium-based 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid (Journal of Molecular Catalysis A: Chemical, 2008, 286, 114). The resulting nanoparticles were found to be effective and selective quasi-homogeneous catalysts towards a wide-range of hydrogenation reactions and the catalyst solution was reused for further catalytic reactions with minimal loss in activity. The synthesis of very pure and clean ILs has allowed a platform to study the effects of impurities in the imidazolium ILs on nanoparticle stability. In a later study, a new mode of stabilization was postulated where the presence of low amounts of 1-methylimidazole has substantial effects on the resulting stability of Au and Pd-Au nanoparticles in these ILs (Chemical Communications, 2009, 812). In further continuation of this study, a comparative study involving four stabilization protocols for nanoparticle stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted). The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O 3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

Moringa oleifera extract (Lam) attenuates Aluminium phosphide-induced acute cardiac toxicity in rats.

PubMed

Gouda, Ahmed S; El-Nabarawy, Nagla A; Ibrahim, Samah F

2018-01-01

Moringa oleifera extract (Lam) has many antioxidant and protective properties. Objective: to investigate the antioxidant activities of Lam in counteracting the high oxidative stress caused by acute sub-lethal aluminium phosphide (AlP) intoxication in rat heart. These activities will be detected by histopathological examination and some oxidative stress biomarkers. a single sub-lethal dose of Alp (2 mg/kg body weight) was administered orally, and Lam was given orally at a dose (100 mg/kg body weight) one hour after receiving AlP to rats. aluminium phosphide caused significant cardiac histopathological changes with a significant increase in malondialdehyde (MDA); lipid peroxidation marker; and a significant depletion of antioxidant enzymes (catalase and glutathione reductase). However, treatment with Lam protected efficiently the cardiac tissue of intoxicated rats by increasing antioxidants levels with slight decreasing in MDA production compared to untreated group. This study suggested that Moringa oleifera extract could possibly restore the altered cardiac histopathology and some antioxidant power in AlP intoxicated rats, and it could even be used as adjuvant therapy against AlP-induced cardiotoxicity.

Characterization of Gallium Indium Phosphide and Progress of Aluminum Gallium Indium Phosphide System Quantum-Well Laser Diode.

PubMed

Hamada, Hiroki

2017-07-28

Highly ordered gallium indium phosphide layers with the low bandgap have been successfully grown on the (100) GaAs substrates, the misorientation toward [01-1] direction, using the low-pressure metal organic chemical vapor deposition method. It is found that the optical properties of the layers are same as those of the disordered ones, essentially different from the ordered ones having two orientations towards [1-11] and [11-1] directions grown on (100) gallium arsenide substrates, which were previously reported. The bandgap at 300 K is 1.791 eV. The value is the smallest ever reported, to our knowledge. The high performance transverse stabilized AlGaInP laser diodes with strain compensated quantum well structure, which is developed in 1992, have been successfully obtained by controlling the misorientation angle and directions of GaAs substrates. The structure is applied to quantum dots laser diodes. This paper also describes the development history of the quantum well and the quantum dots laser diodes, and their future prospects.

Characterization of Gallium Indium Phosphide and Progress of Aluminum Gallium Indium Phosphide System Quantum-Well Laser Diode

PubMed Central

Hamada, Hiroki

2017-01-01

Highly ordered gallium indium phosphide layers with the low bandgap have been successfully grown on the (100) GaAs substrates, the misorientation toward [01−1] direction, using the low-pressure metal organic chemical vapor deposition method. It is found that the optical properties of the layers are same as those of the disordered ones, essentially different from the ordered ones having two orientations towards [1−11] and [11−1] directions grown on (100) gallium arsenide substrates, which were previously reported. The bandgap at 300 K is 1.791 eV. The value is the smallest ever reported, to our knowledge. The high performance transverse stabilized AlGaInP laser diodes with strain compensated quantum well structure, which is developed in 1992, have been successfully obtained by controlling the misorientation angle and directions of GaAs substrates. The structure is applied to quantum dots laser diodes. This paper also describes the development history of the quantum well and the quantum dots laser diodes, and their future prospects. PMID:28773227

Chelating agent-assisted heat treatment of a carbon-supported iron oxide nanoparticle catalyst for PEMFC.

PubMed

Liu, Shyh-Jiun; Huang, Chia-Hung; Huang, Chun-Kai; Hwang, Weng-Sing

2009-08-28

Iron complexes were supported on commercial carbon black and heat treated to create FeO(x)/C catalysts that showed a larger normalized current density and normalized power density than commercial Pt/C catalysts; the coordination number of the iron complexes used affected the formation of the active site for oxygen reduction in PEMFC.

Preparation and Characterization of NiMo/Al2O3Catalyst for Hydrocracking Processing

NASA Astrophysics Data System (ADS)

Widiyadi, Aditya; Guspiani, Gema Adil; Riady, Jeffry; Andreanto, Rikky; Chaiunnisa, Safina Dea; Widayat

2018-02-01

Hydrocracking is a chemical process used in petroleum refineries for converting high boiling hydrocarbons in petroleum crude oils to more valuable lower boiling products such as gasoline, kerosene, and diesel oil that operate at high temperature and pressure. Catalyst was used in hydrocracking to reduce temperature and pressure. Hydrocracking catalyst are composed of active components and support. Alumina is widely used in hydrocracking process as catalyst support due to its high surface area, high thermal stability, and low prices. The objective of this research was preparated NiMo/Al2O3 catalyst that used as hydrocracking catalyst. Catalyst was synthesized by wetness impregnation method and simple heating method with various kind of Al2O3. The physicochemical properties of catalyst were investigated by X-ray diffraction (XRD) to determine type of crystal and scanning electron microscopy (SEM) to determine morphology of the catalyst. The NiMo/Al2O3 catalyst prepared by aluminium potassium sulfate dodecahydrate exhibited the highest crystallinity of 90.23% and it is clear that MoO3 and NiO crystallites are highly dispersed on the NiMo/Al2O3 catalyst which indicates as the best catalyst. The catalytic activity in hydrocracking process was successfully examined to convert fatty acid into hydrocarbon.

Synthesis and characterization of mesoporous hydrocracking catalysts

NASA Astrophysics Data System (ADS)

Munir, D.; Usman, M. R.

2016-08-01

Mesoporous catalysts have shown great prospective for catalytic reactions due to their high surface area that aids better distribution of impregnated metal. They have been found to contain more adsorption sites and controlled pore diameter. Hydrocracking, in the presence of mesoporous catalyst is considered more efficient and higher conversion of larger molecules is observed as compared to the cracking reactions in smaller microporous cavities of traditional zeolites. In the present study, a number of silica-alumina based mesoporous catalysts are synthesized in the laboratory. The concentration and type of surfactants and quantities of silica and alumina sources are the variables studied in the preparation of catalyst supports. The supports prepared are well characterized using SEM, EDX, and N2-BET techniques. Finally, the catalysts are tested in a high pressure autoclave reactor to study the activity and selectivity of the catalysts for the hydrocracking of a model mixture of plastics comprising of LDPE, HDPE, PP, and PS.

Hydrazine Catalyst Production: Sustaining S-405 Technology

NASA Technical Reports Server (NTRS)

Wucherer, E. J.; Cook, Timothy; Stiefel, Mark; Humphries, Randy, Jr.; Parker, Janet

2003-01-01

The development of the iridium-based Shell 405 catalyst for spontaneous decomposition of hydrazine was one of the key enabling technologies for today's spacecraft and launch vehicles. To ensure that this crucial technology was not lost when Shell elected to exit the business, Aerojet, supported by NASA, has developed a dedicated catalyst production facility that will supply catalyst for future spacecraft and launch vehicle requirements. We have undertaken a program to transfer catalyst production from Shell Chemical USA (Houston, TX) to Aerojet's Redmond, WA location. This technology transition was aided by Aerojet's 30 years of catalyst manufacturing experience and NASA diligence and support in sustaining essential technologies. The facility has produced and tested S-405 catalyst to existing Shell 405 specifications and standards. Our presentation will describe the technology transition effort including development of the manufacturing facility, capture of the manufacturing process, test equipment validation, initial batch build and final testing.

ECUT: Energy Conversion and Utilization Technologies program. Heterogeneous catalysis modeling program concept

NASA Technical Reports Server (NTRS)

Voecks, G. E.

1983-01-01

Insufficient theoretical definition of heterogeneous catalysts is the major difficulty confronting industrial suppliers who seek catalyst systems which are more active, selective, and stable than those currently available. In contrast, progress was made in tailoring homogeneous catalysts to specific reactions because more is known about the reaction intermediates promoted and/or stabilized by these catalysts during the course of reaction. However, modeling heterogeneous catalysts on a microscopic scale requires compiling and verifying complex information on reaction intermediates and pathways. This can be achieved by adapting homogeneous catalyzed reaction intermediate species, applying theoretical quantum chemistry and computer technology, and developing a better understanding of heterogeneous catalyst system environments. Research in microscopic reaction modeling is now at a stage where computer modeling, supported by physical experimental verification, could provide information about the dynamics of the reactions that will lead to designing supported catalysts with improved selectivity and stability.

Enhancement of Electrode Stability Using Platinum-Cobalt Nanocrystals on a Novel Composite SiCTiC Support.

PubMed

Millán, María; Zamora, Héctor; Rodrigo, Manuel A; Lobato, Justo

2017-02-22

PtCo alloy catalysts for high temperature PEMFCs (protonic exchange membrane fuel cells) were synthesized on a novel noncarbonaceous support (SiCTiC) using the impregnation method with NaBH 4 as the reducing agent at different synthesis temperatures to evaluate the effect of this variable on their physicochemical and electrochemical properties. The catalysts were characterized by inductively coupled plasma optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscope-energy dispersive X-ray,and temperature-programmed reduction. In addition, the electrochemical characterization (i.e., cyclic voltammetry, oxygen reduction reaction, and chronoamperometry) was carried out with a rotating disk electrode. For the cyclic voltammetry investigation, 400 cycles were performed in hot phosphoric acid and a half-cell to evaluate the stability of the synthesized catalysts. The catalyst synthesized on SiCTiC exhibited excellent durability compared to the catalyst synthesized on a Vulcan support. In addition, all synthesized catalysts exhibited better catalytic activity than that of the PtCo/C catalysts. The best results were observed for the catalyst synthesized at 80 °C due to its shorter Pt-Pt nearest-neighbor and higher alloy degree. Finally, a preliminary stability test was conducted in an HT-PEMFC, and promising results in terms of stability and performance were observed.

CuO based catalysts on modified acidic silica supports tested in the de-NOx reduction.

PubMed

Bennici, Simona; Gervasini, Antonella; Lazzarin, Marta; Ragaini, Vittorio

2005-03-01

A series of dispersed CuO catalysts supported on modified silica supports with Al2O3 (SA), TiO2 (ST), and ZrO2 (SZ) were prepared optimising the adsorption method of copper deposition assisted by ultrasound treatment, already reported in a previous paper (S. Bennici, A. Gervasini, V. Ragaini, Ultrason. Sonochem. 10 (2003) 61). The obtained catalysts were characterized in their bulk (atomic absorption, X-ray diffraction, temperature programmed reduction) and surface (N2 adsorption, X-ray photoelectron spectroscopy, scanning electron microscopy) properties. The morphology of the finished materials was not deeply modified compared with that of the relevant supports. The employed complemented techniques evidenced a well dispersed CuO phase with a copper-support interaction on the most acidic supports (SA and SZ). The catalyst performances were studied in the reaction of selective catalytic reduction of NOx with ethene in oxidizing atmosphere in a flow apparatus under variable times (0.360-0.072 s) and temperatures (200-450 degrees C). The catalysts prepared on the most acidic supports (SA and SZ) were the most active and selective towards N2 formation. They showed a particular interesting activity in the reaction of NO2 reduction besides that of NO reduction.

Highly efficient and durable TiN nanofiber electrocatalyst supports.

PubMed

Kim, Hyun; Cho, Min Kyung; Kwon, Jeong An; Jeong, Yeon Hun; Lee, Kyung Jin; Kim, Na Young; Kim, Min Jung; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Nam, Suk Woo; Lim, Dong-Hee; Cho, EunAe; Lee, Kwan-Young; Kim, Jin Young

2015-11-28

To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst. Pt catalyst nanoparticles (NPs) deposited on the TNFs (Pt/TNFs) were electrochemically characterized with respect to oxygen reduction reaction (ORR) activity and durability in an acidic medium. From the electrochemical tests, the TNF-supported Pt catalyst was better and more stable in terms of its catalytic performance compared to a commercially available carbon-supported Pt catalyst. For example, the initial oxygen reduction performance was comparable for both cases, while the Pt/TNF showed much higher durability from an accelerated degradation test (ADT) configuration. It is understood that the improved catalytic roles of TNFs on the supported Pt NPs for ORR are due to the high electrical conductivity arising from the extended connectivity, high inertness to the electrochemical environment and strong catalyst-support interactions.

Development of a specimen heating holder with an evaporator and gas injector and its application for catalyst.

PubMed

Takeo, Kamino; Toshie, Yaguchi; Mitsuru, Konno; Akira, Watabe; Yasuhira, Nagakubo

2006-10-01

A specimen heating holder equipped with a gas injector and an evaporator has been developed for use with conventional transmission electron microscopes (TEMs). The developed specimen holder allows both synthesis of metal oxide support and deposition of catalyst nano-particles in situ. Since the holder is designed to be used in small gapped high-resolution objective lens pole-piece, all the procedure from the synthesis of support material to the deposition of catalyst as well as the behavior of the catalyst nano-particles on the support can be observed at near atomic resolution. The developed specimen holder was applied to the study of AuPd catalyst. First, air was injected onto heated aluminum particles via a gas injector to synthesize Al(2)O(3) support. Then, nano-particles of AuPd were deposited on the Al(2)O(3) support. After the deposition, the synthesized Al(2)O(3) support was heated and air was injected again to observe behaviors of the deposited AuPd nano-particles at elevated temperatures in the aerial environment. Behaviors of the AuPd nano-particles such as coalescence, segmentation and diffusion to the Al(2)O(3) support were dynamically observed at atomic level high resolution.

New Pt/Alumina model catalysts for STM and in situ XPS studies

NASA Astrophysics Data System (ADS)

Nartova, Anna V.; Gharachorlou, Amir; Bukhtiyarov, Andrey V.; Kvon, Ren I.; Bukhtiyarov, Valerii I.

2017-04-01

The new Pt/alumina model catalysts for STM and in situ XPS studies based on thin alumina film formed over the conductive substrate are proposed. Procedure of platinum deposition developed for porous alumina was adapted for the model alumina support. The set of Pt/AlOx-film samples with the different mean platinum particle size was prepared. Capabilities of in situ XPS investigations of the proposed catalysts were demonstrated in study of NO decomposition on platinum nanoparticles. It is shown that proposed model catalysts behave similarly to Pt/γ-Al2O3 and provide the new opportunities for the instrumental studies of platinum catalysts due to resolving several issues (charging, heating, screening) that are typical for the investigation of the porous oxide supported catalysts.

Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

DOEpatents

Gangwal, S.; Jothimurugesan, K.

1999-07-27

A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption process, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gases from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or passivating the heavy metals on the spent FCC catalyst as an intermediate step.

Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

DOEpatents

Gangwal, Santosh; Jothimurugesan, Kandaswamy

1999-01-01

A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

Anchored nanostructure materials and method of fabrication

DOEpatents

Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

2012-11-27

Anchored nanostructure materials and methods for their fabrication are described. The anchored nanostructure materials may utilize nano-catalysts that include powder-based or solid-based support materials. The support material may comprise metal, such as NiAl, ceramic, a cermet, or silicon or other metalloid. Typically, nanoparticles are disposed adjacent a surface of the support material. Nanostructures may be formed as anchored to nanoparticles that are adjacent the surface of the support material by heating the nano-catalysts and then exposing the nano-catalysts to an organic vapor. The nanostructures are typically single wall or multi-wall carbon nanotubes.

Enhanced Hydrodeoxygenation of m -Cresol over Bimetallic Pt–Mo Catalysts through an Oxophilic Metal-Induced Tautomerization Pathway

DOE PAGES

Robinson, Allison; Ferguson, Glen Allen; Gallagher, James R.; ...

2016-05-26

Supported bimetallic catalysts consisting of a noble metal (e.g., Pt) and an oxophilic metal (e.g., Mo) have received considerable attention for the hydrodeoxygenation of oxygenated aromatic compounds produced from biomass fast pyrolysis. Here, we report that PtMo can catalyze m-cresol deoxygenation via a pathway involving an initial tautomerization step. In contrast, the dominant mechanism on monometallic Pt/Al 2O 3 was found to be sequential Pt-catalyzed ring hydrogenation followed by dehydration on the support. Bimetallic Pt 10Mo 1 and Pt 1Mo 1 catalysts were found to produce the completely hydrogenated and deoxygenated product, methylcyclohexane (MCH), with much higher yields than monometallicmore » Pt catalysts with comparable metal loadings and surface areas. Over an inert carbon support, MCH formation was found to be slow over monometallic Pt catalysts, while deoxygenation was significant for PtMo catalysts even in the absence of an acidic support material. Experimental studies of m-cresol deoxygenation together with density functional theory calculations indicated that Mo sites on the PtMo bimetallic surface dramatically lower the barrier for m-cresol tautomerization and subsequent deoxygenation. The accessibility of this pathway arises from the increased interaction between the oxygen of m-cresol and the Mo sites in the Pt surface. This interaction significantly alters the configuration of the precursor and transition states for tautomerization. Lastly, a suite of catalyst characterization techniques including X-ray absorption spectroscopy (XAS) and temperature-programmed reduction (TPR) indicate that Mo was present in a reduced state on the bimetallic surface under conditions relevant for reaction. Overall, these results suggest that the use of bifunctional metal catalysts can result in new reaction pathways that are unfavorable on monometallic noble metal catalysts.« less

Surface chemistry characterization of hydrodesulfurization and methanol synthesis model nanocatalysts

NASA Astrophysics Data System (ADS)

Komarneni, Mallikharjuna Rao

Surface science investigations of model catalysts have contributed significantly to heterogeneous catalysis over the past several decades. The unique properties of nanomaterials are being exploited in catalysis for the development of highly active and selective catalysts. Surface science investigations of model catalysts such as inorganic fullerene-like (IF) nanoparticles (NP), inorganic nanotubes (INT), and the oxide-supported nanoclusters are included in this dissertation. Thermal desorption spectroscopy and molecular beam scattering were respectively utilized to study the adsorption kinetics and dynamics of gas phase molecules on catalyst surfaces. In addition, ambient pressure kinetics experiments were performed to characterize the catalytic activity of hydrodesulfurization (HDS) nanocatalysts. The nanocatalysts were characterized with a variety of techniques, including Auger electron spectroscopy, x-ray photoelectron spectroscopy, electron microscopy, and x-ray diffraction. The adsorption kinetics studies of thiophene on novel HDS catalysts provided the first evidence for the presence of different adsorption sites on INT-WS2. Additionally, the adsorption sites on IF-MoS2 NP and silica-supported Mo clusters (Mo/silica) were characterized. Furthermore, the C-S bond activation energy of thiophene on Mo/silica was determined. These studies finally led to the fabrication of Ni/Co coated INT-WS2, which showed good catalytic activity towards HDS of thiophene. The studies of methanol synthesis catalysts include the adsorption kinetics and dynamics studies of CO and CO2 on Cu/silica and silica-supported EBL-fabricated Cu/CuOx nanoclusters. The adsorption dynamics of CO on Cu/silica are modeled within the frame work of the capture zone model (CZM), and the active sites of the silica-supported Au/Cu catalysts are successfully mapped. Studies on EBL model catalysts identify the rims of the CuOx nanoclusters as catalytically active sites. This observation has implications for new methanol catalyst design.

Carbon-supported, selenium-modified ruthenium-molybdenum catalysts for oxygen reduction in acidic media.

PubMed

Guinel, Maxime J-F; Bonakdarpour, Arman; Wang, Biao; Babu, Panakkattu K; Ernst, Frank; Ramaswamy, Nagappan; Mukerjee, Sanjeev; Wieckowski, Andrzej

2009-07-20

The stability and oxygen reduction activity of two carbon-supported catalyst materials are reported. The catalysts, Se/Ru and Se/(Ru-Mo), were prepared by using a chemical reduction method. The catalyst nanoparticles were evenly dispersed onto globular amorphous carbon supports, and their average size was ca. 2.4 nm. Thermal treatment at 500 °C for 2 h in an inert argon atmosphere resulted in coarsening of the nanoparticles, and also in some decrease of their activity. A gradual reduction of activity was also observed for Se/Ru during potential-cycle experiments. However, the incorporation of small amounts of Mo into the Se/Ru catalysts considerably improved the stability of the catalyst against dissolution. The Mo-containing samples showed excellent oxygen reduction activities even after cycling the potential 1000 times between 0.7 and 0.9 V. Furthermore, they showed excellent fuel-cell behavior. The performance of the Se/Ru catalysts is greatly improved by the addition of small amounts of elemental Mo. Possible mechanisms responsible for the improvement of the activity are discussed. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nafion induced surface confinement of oxygen in carbon-supported oxygen reduction catalysts

DOE PAGES

Chlistunoff, Jerzy; Sansinena, Jose -Maria

2016-11-17

We studied the surface confinement of oxygen inside layers of Nafion self-assembled on carbon-supported oxygen reduction reaction (ORR) catalysts. It is demonstrated that oxygen accumulates in the hydrophobic component of the polymer remaining in contact with the carbon surface. Furthermore, the amount of surface confined oxygen increases with the degree of carbon surface graphitization, which promotes the self-assembly of the polymer. Planar macrocyclic ORR catalysts possessing a delocalized system of π electrons such as Co and Fe porphyrins and phthalocyanines have virtually no effect on the surface confinement of oxygen, in accordance with their structural similarity to graphitic carbon surfacesmore » where they adsorb. Platinum particles in carbon-supported ORR catalysts with high metal contents (20%) disrupt the self-assembly of Nafion and virtually eliminate the oxygen confinement, but the phenomenon is still observed for low Pt loading (4.8%) catalysts.« less

Catalytic transformation of carbon dioxide and methane into syngas over ruthenium and platinum supported hydroxyapatites

NASA Astrophysics Data System (ADS)

Rêgo De Vasconcelos, Bruna; Zhao, Lulu; Sharrock, Patrick; Nzihou, Ange; Pham Minh, Doan

2016-12-01

This work focused on the catalytic transformation of methane (CH4) and carbon dioxide (CO2) into syngas (mixture of CO and H2). Ruthenium- and platinum-based catalysts were prepared using hydroxyapatite (HAP) as catalyst support. Different methods for metal deposition were used including incipient wetness impregnation (IWI), excess liquid phase impregnation (LIM), and cationic exchange (CEX). Metal particle size varied in large range from less than 1 nm to dozens nm. All catalysts were active at 400-700 °C but only Pt catalyst prepared by IWI method (Pt/HAP IWI) was found stable. The catalytic performance of Pt/HAP IWI could be comparable with the literature data on noble metal-based catalysts, prepared on metal oxide supports. For the first time, water was experimentally quantified as a by-product of the reaction. This helped to correctly buckle the mass balance of the process.

Nafion induced surface confinement of oxygen in carbon-supported oxygen reduction catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chlistunoff, Jerzy; Sansinena, Jose -Maria

We studied the surface confinement of oxygen inside layers of Nafion self-assembled on carbon-supported oxygen reduction reaction (ORR) catalysts. It is demonstrated that oxygen accumulates in the hydrophobic component of the polymer remaining in contact with the carbon surface. Furthermore, the amount of surface confined oxygen increases with the degree of carbon surface graphitization, which promotes the self-assembly of the polymer. Planar macrocyclic ORR catalysts possessing a delocalized system of π electrons such as Co and Fe porphyrins and phthalocyanines have virtually no effect on the surface confinement of oxygen, in accordance with their structural similarity to graphitic carbon surfacesmore » where they adsorb. Platinum particles in carbon-supported ORR catalysts with high metal contents (20%) disrupt the self-assembly of Nafion and virtually eliminate the oxygen confinement, but the phenomenon is still observed for low Pt loading (4.8%) catalysts.« less

Au and Pt nanoparticle supported catalysts tailored for H-2 production: From models to powder catalysts

DOE PAGES

T. D. Nguyen-Phan; Baber, A. E.; Rodriguez, J. A.; ...

2015-12-10

The use of metal nanoparticles (NPs), including Au and Pt, supported over oxides has been pivotal, and is ever increasing in enabling catalytic reactions which target the production of hydrogen. We review here the most recent works pertaining to the fundamental understanding of the structure, morphology, growth, characterization, and intrinsic phenomenological properties of Au– and Pt– based catalysts that influence the reactivity and selectivity to target hydrogen production. We draw on surface science and theoretical methods of model and powder catalysts using high resolution imaging, spectroscopy, scattering experiments, and theoretical studies. Based on these insights we identify key aspects ofmore » studies of supported metal nanoparticle (NP) catalysts for several reactions. The main focus of this review is on the intersection of catalytic chemistry related to the water-gas shift (WGS), oxygenate steam reforming (OSR), and solarassisted reactions (SAR).« less

Interaction potential for indium phosphide: a molecular dynamics and first-principles study of the elastic constants, generalized stacking fault and surface energies.

PubMed

Branicio, Paulo Sergio; Rino, José Pedro; Gan, Chee Kwan; Tsuzuki, Hélio

2009-03-04

Indium phosphide is investigated using molecular dynamics (MD) simulations and density-functional theory calculations. MD simulations use a proposed effective interaction potential for InP fitted to a selected experimental dataset of properties. The potential consists of two- and three-body terms that represent atomic-size effects, charge-charge, charge-dipole and dipole-dipole interactions as well as covalent bond bending and stretching. Predictions are made for the elastic constants as a function of density and temperature, the generalized stacking fault energy and the low-index surface energies.

Molecular fingerprint-region spectroscopy from 5 to 12  μm using an orientation-patterned gallium phosphide optical parametric oscillator.

PubMed

Maidment, Luke; Schunemann, Peter G; Reid, Derryck T

2016-09-15

We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation-patterned gallium phosphide (OP-GaP), which enables the production of high-repetition-rate femtosecond pulses spanning 5-12 μm with average powers in the few to tens of milliwatts range. This is the first example of a broadband OPO operating across the molecular fingerprint region, and we demonstrate its potential by conducting broadband Fourier-transform spectroscopy using water vapor and a polystyrene reference standard.

Electronic properties of hexagonal gallium phosphide: A DFT investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Vipin; Shah, Esha V.; Roy, Debesh R., E-mail: drr@ashd.svnit.ac.in

2016-05-23

A detail density functional investigation is performed to develop hexagonal 2D gallium phosphide material. The geometry, band structure and density of states (total and projected) of 2D hexagonal GaP are reported in detail. It is heartening to note that the developed material is identified as an indirect band gap semiconductor. The indirect gap for this material is predicted as 1.97 eV at K-Γ, and a direct gap of 2.28 eV at K point is achieved, which is very close to the reported direct band gap for zinc blende and buckled structures of GaP.

Thin film photovoltaic device

DOEpatents

Catalano, A.W.; Bhushan, M.

1982-08-03

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Barringerite Fe2P from Pyrometamorphic Rocks of the Hatrurim Formation, Israel

NASA Astrophysics Data System (ADS)

Britvin, S. N.; Murashko, M. N.; Vapnik, E.; Polekhovsky, Yu. S.; Krivovichev, S. V.

2017-12-01

The article provides a detailed mineralogical and crystallochemical description (including refinement of the crystal structure) of the first finding of the phosphide class mineral barringerite, Fe2P, from terrestrial pyrometamorphic rocks of the Hatrurim Formation in Israel. The mineral occurs in the association of the so-called paralavas—initially silicate—carbonate sedimentary rocks that remelted during pyrometamorphic processes at a temperature above 1000°C and at a low pressure. Questions on the genesis and crystal chemistry of barringerite are discussed in connection with another polymorphic iron phosphide, allabogdanite (Fe,Ni)2P.

Low resistance contacts for shallow junction semiconductors

NASA Technical Reports Server (NTRS)

Fatemi, Navid S. (Inventor); Weizer, Victor G. (Inventor)

1994-01-01

A method of enhancing the specific contact resistivity in InP semiconductor devices and improved devices produced thereby are disclosed. Low resistivity values are obtained by using gold ohmic contacts that contain small amounts of gallium or indium and by depositing a thin gold phosphide interlayer between the surface of the InP device and the ohmic contact. When both the thin interlayer and the gold-gallium or gold-indium contact metallizations are used, ultra low specific contact resistivities are achieved. Thermal stability with good contact resistivity is achieved by depositing a layer of refractory metal over the gold phosphide interlayer.

Development of highly active and stable hybrid cathode catalyst for PEMFCs

NASA Astrophysics Data System (ADS)

Jung, Won Suk

Polymer electrolyte membrane fuel cells (PEMFCs) are attractive power sources of the future for a variety of applications including portable electronics, stationary power, and automobile application. However, sluggish cathode kinetics, high Pt cost, and durability issues inhibit the commercialization of PEMFCs. To overcome these drawbacks, research has been focused on alloying Pt with transition metals since alloy catalysts show significantly improved catalytic properties like high activity, selectivity, and durability. However, Pt-alloy catalysts synthesized using the conventional impregnation method exhibit uneven particle size and poor particle distribution resulting in poor performance and/or durability in PEMFCs. In this dissertation, a novel catalyst synthesis methodology is developed and compared with catalysts prepared using impregnation method and commercial catalysts. Two approaches are investigated for the catalyst development. The catalyst durability was studied under U. S. DRIVE Fuel Cell Tech Team suggested protocols. In the first approach, the carbon composite catalyst (CCC) having active sites for oxygen reduction reaction (ORR) is employed as a support for the synthesis of Pt/CCC catalyst. The structural and electrochemical properties of Pt/CCC catalyst are investigated using high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, while RDE and fuel cell testing are carried out to study the electrochemical properties. The synergistic effect of CCC and Pt is confirmed by the observed high activity towards ORR for the Pt/CCC catalyst. The second approach is the synthesis of Co-doped hybrid cathode catalysts (Co-doped Pt/CCC) by diffusing the Co metal present within the CCC support into the Pt nanoparticles during heat-treatment. The optimized Co-doped Pt/CCC catalyst performed better than the commercial catalysts and the catalyst prepared using the impregnation method in PEMFCs and showed high stability under 30,000 potential cycles between 0.6 and 1.0 V. To further increase the stability of the catalyst at high potential cycles (1.0-1.5 V), high temperature treatment is used to obtain graphitized carbon having optimum BET surface area. The novel catalyst synthesis procedure developed in this study was successfully applied for the synthesis of Co-doped Pt catalysts supported on the graphitized carbon which showed high activity and enhanced stability at high potentials.

Defect-rich Ni-Ti layered double hydroxide as a highly efficient support for Au nanoparticles in base-free and solvent-free selective oxidation of benzyl alcohol.

PubMed

Liu, Mengran; Fan, Guoli; Yu, Jiaying; Yang, Lan; Li, Feng

2018-04-17

Tuning the surface properties of supported metal catalysts is of vital importance for governing their catalytic performances in nanocatalysis. Here, we report highly dispersed nanometric gold nanoparticles (NPs) supported on Ni-Ti layered double hydroxides (NiTi-LDHs), which were employed in solvent-free and base-free selective oxidation of benzyl alcohol. A series of characterization techniques demonstrated that defect-rich NiTi-LDHs could efficiently stabilize Au NPs and decrease surface electron density of Au NPs. The as-formed Au/NiTi-LDH catalyst with a Ni/Ti molar ratio of 3 : 1 and an Au loading of 0.71 wt% yielded the highest turnover frequency value of ∼4981 h-1 at 120 °C among tested Au/NiTi-LDH catalysts with different Ni/Ti molar ratios, along with a high benzaldehyde selectivity of 98%. High catalytic efficiency of the catalyst was mainly correlated with surface cooperation between unique defects (i.e. defective Ti3+ species and oxygen vacancies) and abundant hydroxyl groups on the brucite-like layers of the NiTi-LDH support, which could lead to the preferential adsorption and activation of an alcohol hydroxyl moiety in benzyl alcohol and oxygen molecule, as well as the formation of more electron-deficient Ni3+ and Au0 species on the catalyst surface. Furthermore, the present Au/NiTi-LDH catalyst tolerated the oxidation of a wide variety of substrate structures into the corresponding aldehydes, acids or ketones. Our primary results illustrate that defect-rich NiTi-LDHs are promising supports which can efficiently modify surface structure and electronic properties of supported metal catalysts and consequently improve their catalytic performances.

Steam Reforming of Ethylene Glycol over MgAl₂O₄ Supported Rh, Ni, and Co Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mei, Donghai; Lebarbier, Vanessa M.; Xing, Rong

Steam reforming of ethylene glycol (EG) over MgAl₂O₄ supported metal (15 wt.% Ni, 5 wt.% Rh, and 15 wt.% Co) catalysts were investigated using combined experimental and theoretical methods. Compared to highly active Rh and Ni catalysts with 100% conversion, the steam reforming activity of EG over the Co catalyst is comparatively lower with only 42% conversion under the same reaction conditions (500°C, 1 atm, 119,000 h⁻¹, S/C=3.3 mol). However, CH₄ selectivity over the Co catalyst is remarkably lower. For example, by varying the gas hour space velocity (GHSV) such that complete conversion is achieved for all the catalysts, CH₄more » selectivity for the Co catalyst is only 8%, which is much lower than the equilibrium CH₄ selectivity of ~ 24% obtained for both the Rh and Ni catalysts. Further studies show that varying H₂O concentration over the Co catalyst has a negligible effect on activity, thus indicating zero-order dependence on H₂O. These experimental results suggest that the supported Co catalyst is a promising EG steam reforming catalyst for high hydrogen production. To gain mechanistic insight for rationalizing the lower CH₃ selectivity observed for the Co catalyst, the initial decomposition reaction steps of ethylene glycol via C-O, O-H, C-H, and C-C bond scissions on the Rh(111), Ni(111) and Co(0001) surfaces were investigated using density functional theory (DFT) calculations. Despite the fact that the bond scission sequence in the EG decomposition on the three metal surfaces varies, which leads to different reaction intermediates, the lower CH₄ selectivity over the Co catalyst, as compared to the Rh and Ni catalysts, is primarily due to the higher barrier for CH₄ formation. The higher S/C ratio enhances the Co catalyst stability, which can be elucidated by the facile water dissociation and an alternative reaction path to remove the CH species as a coking precursor via the HCOH formation. This work was financially supported by the United States Department of Energy (DOE)’s Bioenergy Technologies Office (BETO) and performed at the Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for DOE by Battelle Memorial Institute. Computing time and advanced catalyst characterization use was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research and located at PNNL.« less

Steam reforming of fuel to hydrogen in fuel cell

DOEpatents

Young, J.E.; Fraioli, A.V.

1983-07-13

A fuel cell is described capable of utilizing a hydrocarbon such as methane as fuel and having an internal dual catalyst system within the anode zone, the dual catalyst system including an anode catalyst supporting and in heat conducting relationship with a reforming catalyst with heat for the reforming reaction being supplied by the reaction at the anode catalyst.

Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

PubMed

Andersen, Shuang Ma; Skou, Eivind

2014-10-08

Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase.

Magnetic nanoparticle supported phosphotungstic acid: An efficient catalyst for the synthesis of xanthene derivatives

NASA Astrophysics Data System (ADS)

Patel, Nipun; Katheriya, Deepak; Dadhania, Harsh; Dadhania, Abhishek

2018-05-01

Magnetic nanoparticle supported phosphotungstic acid (Fe3O4@SiO2-HPW) was applied as a highly efficient catalyst for the synthesis of 14H-dibenzoxanthene derivatives via condensation reaction of 2-naphthol and aryl aldehydes. The catalyst was found highly efficient for the synthesis of xanthene derivatives under solvent free condition. The catalyst showed high activity and stability during the reaction and provided excellent yield of the corresponding products in short reaction time. All the synthesized compounds were characterized through FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Furthermore, the catalyst is magnetically recoverable and can be reused several times without significant loss of its catalytic activity.

Supported cluster catalysts synthesized to be small, simple, selective, and stable

DOE PAGES

Guan, Erjia; Fang, Chia-Yu; Yang, Dong; ...

2018-01-01

Molecular metal complexes on supports have drawn wide attention as catalysts offering new properties and opportunities for precise synthesis to make uniform catalytic species that can be understood in depth.

Surface-complexation synthesis of silica-supported high-loading well-dispersed reducible nano-Co3O4 catalysts using CoIII ammine hydroxo complexes

NASA Astrophysics Data System (ADS)

Zhang, Weidong; Pan, Feng; Li, Jinjun; Wang, Zhen; Ding, Wei; Qin, Yi; Wu, Feng

2018-06-01

Silica-supported highly dispersed cobalt oxides prepared by adsorption are likely to be poorly reducible Co-phyllosilicates or CoO species. Here we report the synthesis of silica-supported monodispersed spinel nano-Co3O4 catalysts by inner-sphere complexation using CoIII ammine hydroxo complexes as precursors. The precursors were facilely prepared by stirring ammoniacal CoII solutions exposed to air. The cobalt loadings (up to 188 mg/g) and particle sizes (3-10 nm) were tailored by successive complexation-calcination cycles. Such catalysts showed significantly superior reducibility and catalytic activity in complete propane oxidation in comparison to supported Co-phyllosilicates and CoO. A further development of this synthesis process may provide a variety of cobalt-based catalysts for important catalytic applications.

An extraordinarily stable catalyst: Pt NPs supported on two-dimensional Ti3C2X2 (X = OH, F) nanosheets for oxygen reduction reaction.

PubMed

Xie, Xiaohong; Chen, Siguo; Ding, Wei; Nie, Yao; Wei, Zidong

2013-10-03

High dispersion Pt nanoparticles supported on 2D Ti3C2X2 (X = OH, F) nanosheets are presented and electro-chemical measurements confirm that the Pt/Ti3C2X2 catalyst shows enhanced durability and improved ORR activity compared with the commercial Pt/C catalyst.

Particle size and support effects in electrocatalysis.

PubMed

Hayden, Brian E

2013-08-20

Researchers increasingly recognize that, as with standard supported heterogeneous catalysts, the activity and selectivity of supported metal electrocatalysts are influenced by particle size, particle structure, and catalyst support. Studies using model supported heterogeneous catalysts have provided information about these effects. Similarly, model electrochemical studies on supported metal electrocatalysts can provide insight into the factors determining catalytic activity. High-throughput methods for catalyst synthesis and screening can determine systematic trends in activity as a function of support and particle size with excellent statistical certainty. In this Account, we describe several such studies investigating methods for dispersing precious metals on both carbon and oxide supports, with particular emphasis on the prospects for the development of low-temperature fuel-cell electrocatalysts. One key finding is a decrease in catalytic activity with decreasing particle size independent of the support for both oxygen reduction and CO oxidation on supported gold and platinum. For these reactions, there appears to be an intrinsic particle size effect that results in a loss of activity at particle sizes below 2-3 nm. A titania support, however, also increases activity of gold particles in the electrooxidation of CO and in the reduction of oxygen, with an optimum at 3 nm particle size. This optimum may represent the superposition of competing effects: a titania-induced enhanced activity versus deactivation at small particle sizes. The titania support shows catalytic activity at potentials where carbon-supported and bulk-gold surfaces are normally oxidized and CO electrooxidation is poisoned. On the other hand, platinum on amorphous titania shows a different effect: the oxidation reduction reaction is strongly poisoned in the same particle size range. We correlated the influence of the titania support with titania-induced changes in the surface redox behavior of the platinum particles. For both supported gold and platinum particles in electrocatalysis, we observe parallels to the effects of particle size and support in the equivalent heterogeneous catalysts. Studies of model supported-metal electrocatalysts, performs efficiently using high throughput synthetic and screening methodologies, will lead to a better understanding of the mechanisms responsible for support and particle size effects in electrocatalysis, and will drive the development of more effective and robust catalysts in the future.

International Conference on Indium Phosphide and Related Materials, Held in Cape Cod, Massachusetts, on 11 - 15 May 1997.

DTIC Science & Technology

1998-01-14

runaway cells are very uniform across the wafer. On-wafer active load- causing the so-called current collapse. Using a Au air- pull measurement was...Input Power [ dBm] support and encouragement. References Fig. 4: On-wafer load- pull measurement at 9 GHz. [1] P. M. Asbeck, M. C. F. Chang, J. A...Measured Load Pull Characteristics of the 0.15gm x 300gm GaInAs/InP HEMT at 7GHz. 160 exceeded 830 mS/mm for > 0.5V. The 140 small-signal output

Sulfidation of Co/Al[sub 2]O[sub 3] and CoMo/Al[sub 2]O[sub 3] catalysts studied by Moessbauer emission spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craje, M.W.J.; Kraan, A.M. van der; Beer, V.H.J. de

1993-10-01

The structure of hydrodesulfurization catalysts is relevant to many industries. The sulfidation of uncalcined and calcined alumina-supported cobalt and cobalt-molybdenum catalysts was systematically studied by means of in situ Moessbauer emission spectroscopy (MES) at room temperature. The spectra obtained during the stepwise sulfidation of the uncalcined catalysts clearly resemble those observed for carbon-supported ones. Hence, the interpretation of the spectra of the alumina-supported catalysts is based on the conclusions drawn from the MES studies of the carbon-supported catalysts, which are less complex because Co ions do not diffuse into the support. It is demonstrated that not only in sulfided CoMo/Al[submore » 2]O[sub 3], but also in sulfided Co/Al[sub 2]O[sub 3], catalysts Co-sulfide species with a [open quotes]Co-Mo-S[close quotes]-type quadrupole splitting can be formed. It is concluded that the Co-sulfide species formed in sulfided Co/Al[sub 2]O[sub 3] and CoMo/Al[sub 2]O[sub 3] catalysts are essentially the same, only the particle size and ordering of the Co-sulfide species may differ, as in the case of Co/C and CoMo/C catalysts. The function of the Mo, which is present as MoS[sub 2], is merely to stabilize very small Co-sulfide particles, which in the limit contain only one single Co atom. Furthermore, it turns out that the value of the electric quadrupole splitting (Q.S. value) of the Co-sulfide phase in the sulfided catalysts depends on the sulfiding temperature and Co content. This observation leads to the conclusion that large Q.S. values point to the presence of very small Co-sulfide entities or particles (the lower limit being [open quotes]particles[close quotes] containing only one Co atom, such as proposed in the [open quotes]Co-Mo-S[close quotes] model), whereas small Q.S. values point to the presence of large Co-sulfide particles (the upper limit being crystalline Co[sub 9]S[sub 8]). 28 refs., 7 figs., 6 tabs.« less

Catalysts for low-energy aldehyde processes

NASA Technical Reports Server (NTRS)

Gupta, A.; Rembaum, A.; Frazier, C.; Gray, H. B.

1977-01-01

Photochemical reaction of dicobalt octacarbonyl with polymeric support systems results in formation of polymer bonded metal catalyst. Catalyst is used in hydroformylation (addition of carbon dioxide and hydrogen) of olefins to yield aldehydes.

Catalytic wet air oxidation of coke-plant wastewater on ruthenium-based eggshell catalysts in a bubbling bed reactor.

PubMed

Yang, M; Sun, Y; Xu, A H; Lu, X Y; Du, H Z; Sun, C L; Li, C

2007-07-01

Catalytic wet air of coke-plant wastewater was studied in a bubbling bed reactor. Two types of supported Ru-based catalysts, eggshell and uniform catalysts, were employed. Compared with the results in the wet air oxidation of coke-plant wastewater, supported Ru uniform catalysts showed high activity for chemical oxygen demand (COD) and ammonia/ammonium compounds (NH3-N) removal at temperature of 250 degrees C and pressure of 4.8 MPa, and it has been demonstrated that the catalytic activity of uniform catalyst depended strongly on the distribution of active sites of Ru on catalyst. Compared to the corresponding uniform catalysts with the same Ru loading (0.25 wt.% and 0.1 wt.%, respectively), the eggshell catalysts showed higher activities for CODcr removal and much higher activities for NH3-N degradation. The high activity of eggshell catalyst for treatment of coke-plant wastewater can be attributed to the higher density of active Ru sites in the shell layer than that of the corresponding uniform catalyst with the same Ru loading. It has been also evidenced that the active Ru sites in the internal core of uniform catalyst have very little or no contribution to CODcr and NH3-N removal in the total oxidation of coke-plant wastewater.

PdRu/C catalysts for ethanol oxidation in anion-exchange membrane direct ethanol fuel cells

NASA Astrophysics Data System (ADS)

Ma, Liang; He, Hui; Hsu, Andrew; Chen, Rongrong

2013-11-01

Carbon supported PdRu catalysts with various Pd:Ru atomic ratios were synthesized by impregnation method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electrochemical half-cell tests, and the anion-exchange membrane direct ethanol fuel cell (AEM-DEFC) tests. XRD results suggest that the PdRu metal exists on carbon support in an alloy form. TEM study shows that the bimetallic PdRu/C catalysts have slightly smaller average particle size than the single metal Pd/C catalyst. Lower onset potential and peak potential and much higher steady state current for ethanol oxidation in alkaline media were observed on the bimetallic catalysts (PdxRuy/C) than on the Pd/C, while the activity for ethanol oxidation on the pure Ru/C was not noticeable. By using Pd/C anode catalysts and MnO2 cathode catalysts, AEM-DEFCs free from the expensive Pt catalyst were assembled. The AEM DEFC using the bimetallic Pd3Ru/C anode catalyst showed a peak power density as high as 176 mW cm-2 at 80 °C, about 1.8 times higher than that using the single metal Pd/C catalyst. The role of Ru for enhancing the EOR activity of Pd/C catalysts is discussed.

Synthesis and characterization of molybdenum catalysts supported on {gamma}-Al{sub 2}O{sub 3}-CeO{sub 2} composite oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farooq, Muhammad; Ramli, Anita; Subbarao, Duvvuri

2012-09-26

The physical and chemical properties of a catalyst play a vital role in various industrial applications. Molybdenum catalysts supported on {gamma}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3}-CeO{sub 2} mixed oxides with varying loading of CeO{sub 2} (5, 10, 15, 20 wt% with respect to {gamma}-Al{sub 2}O{sub 3}) were prepared by wet impregnation method. The physiochemical properties of these synthesized Mo catalysts were studied with various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive analysis (FESEM-EDX) and X-ray fluorescence spectrometer (XRF). The results showed that the addition of CeO{submore » 2} into the support affected the binding energies of the elements and reducibility of the metal oxides formed after calcination of catalyst samples due to the change in metal-support interaction. Further, the characterization techniques showed that the active metal was well dispersed on the surface of support material.« less

Acidic Mesoporous Zeolite ZSM-5 Supported Cu Catalyst with Good Catalytic Performance in the Hydroxysulfurization of Styrenes with Disulfides.

PubMed

Hu, Jun; Zhu, Chaojie; Xia, Feifei; Fang, Zhongxue; Yang, Fengli; Weng, Jushi; Yao, Pengfei; Zheng, Chunzhi; Dong, Hai; Fu, Wenqian

2017-12-19

Development of highly active heterogeneous catalysts is an effective strategy for modern organic synthesis chemistry. In this work, acidic mesoporous zeolite ZSM-5 (HZSM-5-M), acidic-free mesoporous zeolite TS-1 (TS-1-M), and basic ETS-10 zeolite supported metal Cu catalysts were prepared to investigate their catalytic performances in the hydroxysulfurization of styrenes with diaryl disulfides. The effect of pore size and acidities of the supports, as well as the Cu species electronic properties of the catalysts on reaction activity were investigated. The results show that Cu⁺ and Cu 2+ binded on HZSM-5-M show the highest activity and product selectivity for the desired β -hydroxysulfides compounds.

Acidic Mesoporous Zeolite ZSM-5 Supported Cu Catalyst with Good Catalytic Performance in the Hydroxysulfurization of Styrenes with Disulfides

PubMed Central

Hu, Jun; Zhu, Chaojie; Xia, Feifei; Fang, Zhongxue; Yang, Fengli; Weng, Jushi; Yao, Pengfei; Zheng, Chunzhi; Dong, Hai; Fu, Wenqian

2017-01-01

Development of highly active heterogeneous catalysts is an effective strategy for modern organic synthesis chemistry. In this work, acidic mesoporous zeolite ZSM-5 (HZSM-5-M), acidic-free mesoporous zeolite TS-1 (TS-1-M), and basic ETS-10 zeolite supported metal Cu catalysts were prepared to investigate their catalytic performances in the hydroxysulfurization of styrenes with diaryl disulfides. The effect of pore size and acidities of the supports, as well as the Cu species electronic properties of the catalysts on reaction activity were investigated. The results show that Cu+ and Cu2+ binded on HZSM-5-M show the highest activity and product selectivity for the desired β-hydroxysulfides compounds. PMID:29257075

Catalytic combustion of methane over commercial catalysts in presence of ammonia and hydrogen sulphide.

PubMed

Hurtado, Paloma; Ordóñez, Salvador; Vega, Aurelio; Díez, Fernando V

2004-05-01

The performance of different commercially available catalysts (supported Pd, Pt, Rh, bimetallic Pd-Pt, and Cr-Cu-Ti oxide catalyst) for the oxidation of methane, alone and in presence of ammonia and hydrogen sulphide is studied in this work. Catalysts performance was evaluated both in terms of activity and resistance to poisoning. The main conclusions are that supported Pd and Rh, present the highest activities for methane oxidation, both alone and in presence of ammonia, whereas they are severely poisoned in presence of H2S. Pt and Cr-Cu-Ti are less active but more sulphur resistant, but their activity is lower than the residual activity of sulphur-deactivated Pd and Rh catalysts. The Pd-Pt catalyst exhibits low activity and it is quickly deactivated in presence of hydrogen sulphide.

Hydrogen production from biomass gasification using biochar as a catalyst/support.

PubMed

Yao, Dingding; Hu, Qiang; Wang, Daqian; Yang, Haiping; Wu, Chunfei; Wang, Xianhua; Chen, Hanping

2016-09-01

Biochar is a promising catalyst/support for biomass gasification. Hydrogen production from biomass steam gasification with biochar or Ni-based biochar has been investigated using a two stage fixed bed reactor. Commercial activated carbon was also studied as a comparison. Catalyst was prepared with an impregnation method and characterized by X-ray diffraction, specific surface and porosity analysis, X-ray fluorescence and scanning electron micrograph. The effects of gasification temperature, steam to biomass ratio, Ni loading and bio-char properties on catalyst activity in terms of hydrogen production were explored. The Ni/AC catalyst showed the best performance at gasification temperature of 800°C, S/B=4, Ni loading of 15wt.%. Texture and composition characterization of the catalysts suggested the interaction between volatiles and biochar promoted the reforming of pyrolysis volatiles. Cotton-char supported Ni exhibited the highest activity of H2 production (64.02vol.%, 92.08mgg(-1) biomass) from biomass gasification, while rice-char showed the lowest H2 production. Copyright © 2016 Elsevier Ltd. All rights reserved.

A palladium-doped ceria@carbon core-sheath nanowire network: a promising catalyst support for alcohol electrooxidation reactions.

PubMed

Tan, Qiang; Du, Chunyu; Sun, Yongrong; Du, Lei; Yin, Geping; Gao, Yunzhi

2015-08-28

A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique interconnected one-dimensional core-sheath structure is revealed to facilitate immobilization of the metal catalysts, leading to the improved durability. This core-sheath nanowire network opens up a new strategy for catalyst performance optimization for next-generation fuel cells.

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide

PubMed Central

Anthonysamy, Shahreen Binti Izwan; Afandi, Syahidah Binti; Khavarian, Mehrnoush

2018-01-01

Various types of carbon-based and non-carbon-based catalyst supports for nitric oxide (NO) removal through selective catalytic reduction (SCR) with ammonia are examined in this review. A number of carbon-based materials, such as carbon nanotubes (CNTs), activated carbon (AC), and graphene (GR) and non-carbon-based materials, such as Zeolite Socony Mobil–5 (ZSM-5), TiO2, and Al2O3 supported materials, were identified as the most up-to-date and recently used catalysts for the removal of NO gas. The main focus of this review is the study of catalyst preparation methods, as this is highly correlated to the behaviour of NO removal. The general mechanisms involved in the system, the Langmuir–Hinshelwood or Eley–Riedeal mechanism, are also discussed. Characterisation analysis affecting the surface and chemical structure of the catalyst is also detailed in this work. Finally, a few major conclusions are drawn and future directions for work on the advancement of the SCR-NH3 catalyst are suggested. PMID:29600136

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide.

PubMed

Anthonysamy, Shahreen Binti Izwan; Afandi, Syahidah Binti; Khavarian, Mehrnoush; Mohamed, Abdul Rahman Bin

2018-01-01

Various types of carbon-based and non-carbon-based catalyst supports for nitric oxide (NO) removal through selective catalytic reduction (SCR) with ammonia are examined in this review. A number of carbon-based materials, such as carbon nanotubes (CNTs), activated carbon (AC), and graphene (GR) and non-carbon-based materials, such as Zeolite Socony Mobil-5 (ZSM-5), TiO 2 , and Al 2 O 3 supported materials, were identified as the most up-to-date and recently used catalysts for the removal of NO gas. The main focus of this review is the study of catalyst preparation methods, as this is highly correlated to the behaviour of NO removal. The general mechanisms involved in the system, the Langmuir-Hinshelwood or Eley-Riedeal mechanism, are also discussed. Characterisation analysis affecting the surface and chemical structure of the catalyst is also detailed in this work. Finally, a few major conclusions are drawn and future directions for work on the advancement of the SCR-NH 3 catalyst are suggested.

Synthesis of honeycomb-like mesoporous nitrogen-doped carbon nanospheres as Pt catalyst supports for methanol oxidation in alkaline media

NASA Astrophysics Data System (ADS)

Zhang, Yunmao; Liu, Yong; Liu, Weihua; Li, Xiying; Mao, Liqun

2017-06-01

This paper reports the convenient synthesis of honeycomb-like mesoporous nitrogen-doped carbon spheres (MNCS) using a self-assembly strategy that employs dopamine (DA) as a carbon and nitrogen precursor and a polystyrene-b-poly(ethylene oxide) (PS173-b-PEO170) diblock copolymer as a soft template. The MNCS have large BET surface areas of up to 554 m2 g-1 and high nitrogen contents of up to 6.9 wt%. The obtained MNCS are used as a support for Pt catalysts, which promote methanol oxidation in alkaline media. The MNCS-supported Pt (Pt/MNCS) catalyst has a larger electrochemically active surface area (ESA) (89.2 m2 g-1) than does a commercially available Vulcan XC-72R supported Pt/C catalyst. Compared to the Pt/C catalyst, Pt/MNCS displays a higher peak current density (1007 mA mg-1) and is more stable during methanol oxidation. These improvements are attributed to the honeycomb-like porous structure of the MNCS and the introduction of nitrogen to the carbon support. The MNCS effectively stabilize Pt nanoparticles and assuage the agglomeration of the nanoparticles, suggesting that MNCS are potential and promising application as electrocatalyst supports in alkaline direct methanol fuel cells.

Origin of the Excellent Performance of Ru on Nitrogen-Doped Carbon Nanofibers for CO2 Hydrogenation to CH4.

PubMed

Roldán, Laura; Marco, Yanila; García-Bordejé, Enrique

2017-03-22

Carbon materials have rarely been used as support for CO 2 methanation, which is usually carried out using catalysts supported on metal oxides. Here, it is shown that Ru nanoparticles supported on nitrogen-doped carbon nanofibers (NCNF) provide competitive CH 4 production rate and stability compared to Al 2 O 3 -supported catalysts. Contrary to the general belief about the inert nature of carbon supports, it is demonstrated that NCNF is a non-innocent spectator in CO 2 methanation due to its ability to store a high amount of CO ad reaction intermediates. This explains the excellent catalytic behaviour afforded by this unconventional catalyst support. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective catalysts and their preparation for catalytic hydrocarbon synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iglesia, E.; Vroman, H.; Soled, S.

1991-07-30

This patent describes a method for preparing a supported cobalt catalyst particle. It comprises contacting a support particle with a molten cobalt salt, for a period sufficient to impregnate substantially all of the molten cobalt salt on the support to a depth of less than about 200 {mu}m; drying the supported cobalt salt obtained; reducing the cobalt of the supported cobalt salt to metallic cobalt by heating the salt in the presence of H{sub 2}, wherein the heating is conducted at a rate of less than about 1{degrees} C./min. up to a maximum temperature ranging from about 100{degrees} C. tomore » about 500{degrees} C., to produce a supported cobalt catalyst particle.« less

Enhanced catalyst for conversion of syngas to liquid motor fuels

DOEpatents

Coughlin, Peter K.; Rabo, Jule A.

1985-01-01

Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

Enhanced catalyst for conversion of syngas to liquid motor fuels

DOEpatents

Coughlin, P.K.; Rabo, J.A.

1985-12-03

Synthesis gas comprising carbon monoxide and hydrogen is converted to C[sub 5][sup +] hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising a SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

XPS and Raman studies of Pt catalysts supported on activated carbon

NASA Astrophysics Data System (ADS)

Tyagi, Deepak; Varma, Salil; Bharadwaj, S. R.

2018-04-01

Activated carbon is a widely used support for dispersing noble metals in addition to its many applications. We have prepared platinum catalyst supported on activated carbon for HI decomposition reaction of I-S thermochemical process of hydrogen generation. These catalysts were characterized by XPS and Raman before and after using for the reaction. It was observed that platinum is present in zero oxidation state, while carbon is present is both sp2 and sp3 hybridized forms along with some amount of it bonded to oxygen.

Synthesis and Stabilization of Supported Metal Catalysts by Atomic Layer Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Junling; Elam, Jeffrey W.; Stair, Peter C.

2013-03-12

Supported metal nanoparticles are among the most important cata-lysts for many practical reactions, including petroleum refining, automobile exhaust treatment, and Fischer–Tropsch synthesis. The catalytic performance strongly depends on the size, composition, and structure of the metal nanoparticles, as well as the underlying support. Scientists have used conventional synthesis methods including impregnation, ion exchange, and deposition–precipitation to control and tune these factors, to establish structure–performance relationships, and to develop better catalysts. Meanwhile, chemists have improved the stability of metal nanoparticles against sintering by the application of protective layers, such as polymers and oxides that encapsulate the metal particle. This often leadsmore » to decreased catalytic activity due to a lack of precise control over the thickness of the protective layer. A promising method of catalyst synthesis is atomic layer deposition (ALD). ALD is a variation on chemical vapor deposition in which metals, oxides, and other materials are deposited on surfaces by a sequence of self-limiting reactions. The self-limiting character of these reactions makes it possible to achieve uniform deposits on high-surface-area porous solids. Therefore, design and synthesis of advanced catalysts on the nanoscale becomes possible through precise control over the structure and composition of the underlying support, the catalytic active sites, and the protective layer. In this Account, we describe our advances in the synthesis and stabilization of supported metal catalysts by ALD. After a short introduction to the technique of ALD, we show several strategies for metal catalyst synthesis by ALD that take advantage of its self-limiting feature. Monometallic and bimetallic catalysts with precise control over the metal particle size, composition, and structure were achieved by combining ALD sequences, surface treatments, and deposition temperature control. Next, we describe ALD oxide overcoats applied with atomically precise thickness control that stabilize metal catalysts while preserving their catalytic function. We also discuss strategies for generation and control over the porosity of the overcoats that allow the embedded metal particles to remain accessible by reactants, and the details for ALD alumina overcoats on metal catalysts. Moreover, using methanol decomposition and oxidative dehydrogenation of ethane as probe reactions, we demonstrate that selectively blocking low coordination metal sites by oxide overcoats can provide another strategy to enhance both the durability and selectivity of metal catalysts.« less

A palladium-doped ceria@carbon core-sheath nanowire network: a promising catalyst support for alcohol electrooxidation reactions

NASA Astrophysics Data System (ADS)

Tan, Qiang; Du, Chunyu; Sun, Yongrong; Du, Lei; Yin, Geping; Gao, Yunzhi

2015-08-01

A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique interconnected one-dimensional core-sheath structure is revealed to facilitate immobilization of the metal catalysts, leading to the improved durability. This core-sheath nanowire network opens up a new strategy for catalyst performance optimization for next-generation fuel cells.A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique interconnected one-dimensional core-sheath structure is revealed to facilitate immobilization of the metal catalysts, leading to the improved durability. This core-sheath nanowire network opens up a new strategy for catalyst performance optimization for next-generation fuel cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03023d

A new generation of zirconia supported metal oxide catalysts for converting low grade renewable feedstocks to biodiesel.

PubMed

Kim, Manhoe; DiMaggio, Craig; Salley, Steven O; Simon Ng, K Y

2012-08-01

A new class of zirconia supported mixed metal oxides (ZnO-TiO(2)-Nd(2)O(3)/ZrO(2) and ZnO-SiO(2)-Yb(2)O(3)/ZrO(2)) has demonstrated the ability to convert low quality, high free fatty acid (FFA) bio-oils into biodiesel. Pelletized catalysts of ZrO(2) supported metal oxides were prepared via a sol-gel process and tested in continuous flow packed bed reactors for up to 6 months. In a single pass, while operating at mild to moderate reaction conditions, 195 °C and 300 psi, these catalysts can perform simultaneous esterification and transesterification reactions on feedstock of 33% FFA and 67% soybean oil to achieve FAME yields higher than 90%. Catalytic activity of the ZrO(2) supported metal oxide catalysts was highly dependent on the metal oxide composition. These heterogeneous catalysts will enable biodiesel manufacturers to avoid problems inherent in homogeneous processes, such as separation and washing, corrosive conditions, and excessive methanol usage. Copyright © 2012 Elsevier Ltd. All rights reserved.

Gold-supported cerium-doped NiO x catalysts for water oxidation

DOE PAGES

Ng, Jia Wei Desmond; García-Melchor, Max; Bajdich, Michal; ...

2016-04-29

Here, the development of high-performance catalysts for the oxygen-evolution reaction (OER) is paramount for cost-effective conversion of renewable electricity to fuels and chemicals. Here we report the significant enhancement of the OER activity of electrodeposited NiO x films resulting from the combined effects of using cerium as a dopant and gold as a metal support. This NiCeO x–Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts yet reported. On the basis of experimental observations and theoretical modelling, we ascribe the activity to a combination of electronic, geometric and support effects, where highlymore » active under-coordinated sites at the oxide support interface are modified by the local chemical binding environment and by doping the host Ni oxide with Ce. The NiCeO x–Au catalyst is further demonstrated in a device context by pairing it with a nickel–molybdenum hydrogen evolution catalyst in a water electrolyser, which delivers 50 mA consistently at 1.5 V over 24 h of continuous operation.« less

Novel application of thermally expanded graphite as the support of catalysts for direct synthesis of DMC from CH3OH and CO2.

PubMed

Bian, J; Xiao, M; Wang, S J; Lu, Y X; Meng, Y Z

2009-06-01

Novel Cu-Ni bimetallic catalysts supported on thermally expanded graphite (TEG) were prepared as an example to show the particular characteristics of TEG as a carbon support material. The structures of TEG and the synthesized Cu-Ni/TEG catalysts were characterized using BET, FTIR, TG, SEM, TEM, XRD and TPR techniques. The catalytic activities of the prepared catalysts were investigated by performing micro-reaction in the direct synthesis of dimethyl carbonate (DMC) from CH3OH and CO2. The experimental results indicated that the prepared Cu-Ni/TEG catalysts exhibited highly catalytic activity. Under the optimal catalytic conditions at 100 degrees C and under 1.2 MPa, the highest conversion of CH3OH of 4.97% and high selectivity of DMC of 89.3% can be achieved. The highly catalytic activity of Cu-Ni/TEG in DMC synthesis can be attributed to the synergetic effects of metal Cu, Ni and Cu-Ni alloy in the activation of CH3OH and CO2 and the particular characteristics of TEG as a carbon support material.

Impact Chemistry and the Origin of Life

NASA Astrophysics Data System (ADS)

Melosh, H. J.; Pasek, M.

2012-12-01

Most discussions of global environmental effects of large impacts focus on changes deleterious to extant life. However, impacts may also produce changes that enhance or even create conditions beneficial to the origin of life. Many other authors have discussed impact delivery of organic molecules, and some have shown the shock synthesis of prebiotic molecules such as amino acids during impact. Our past work on the chemistry of impacts demonstrated that strong chemical reduction occurs in impact melt ejecta (spherules and melt droplets; tektites). Here we focus on the element phosphorus (P), whose role is crucial in biology as the backbone of DNA and RNA, and in metabolic biochemical energy transfer. Pasek previously showed that reduced P readily enters into interesting biological compounds with organic molecules in aqueous solution, and that these reduced P compounds may generate structures similar to sugar phosphates, which are critical to life as we know it. In this talk we argue that impact reduction of P transforms terrestrial and meteoritic phosphates bearing an oxidation state of +5 to the lower redox states of +3 (phosphites) and 0 as an alloy with metal (phosphides). We base this argument on studies of fulgurites—glasses formed by cloud-to-ground lightning—that bear phosphides and phosphites as major carriers of P. Fulgurite chemistry frequently parallels that of impact glasses. Additionally, thermodynamic calculations show that separation of an O-rich vapor from a melt readily results in the transformation of phosphate to phosphites and metal phosphides. These results are confirmed by the presence of metal phosphides within tektites. The impact reduction of phosphates followed by global dispersal of reduced P in the form of glassy droplets likely played a major role in the origin of life on Earth and perhaps on other young planets.

Aqueous aerobic oxidation of alkyl arenes and alcohols catalyzed by copper(II) phthalocyanine supported on three-dimensional nitrogen-doped graphene at room temperature.

PubMed

Mahyari, Mojtaba; Laeini, Mohammad Sadegh; Shaabani, Ahmad

2014-07-25

Copper(ii) tetrasulfophthalocyanine supported on three-dimensional nitrogen-doped graphene-based frameworks was synthesized and introduced as a bifunctional catalyst for selective aerobic oxidation of alkyl arenes and alcohols to the corresponding carbonyl compounds. The ease of catalyst separation, high turnover, low catalyst loading and recyclability could potentially render it applicable in industrial setting.

Catalysts for the Oxidation of Carbon Monoxide at Low Temperatures.

DTIC Science & Technology

1979-11-21

Four catalysts ( hopcalite , Whetlerite, a supported palladium, and a supported platinum) were tested for efficiency in promoting the oxidation of...carbon monoxide (CO). At room temperature and 50% RH, hopcalite has no catalytic capability and platinum has practically none. At room temperature and 15...RH, hopcalite is superior to platinum in catalyzing the oxidation of CO. Hopcalite is more efficient than either of the other three catalysts in the

Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing.

PubMed

Xie, Jian-De; Gu, Siyong; Zhang, Houan

2017-09-21

This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period (i.e., 10 min) to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1-12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor.

Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing

PubMed Central

Xie, Jian-De; Zhang, Houan

2017-01-01

This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period (i.e., 10 min) to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1–12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor. PMID:28934104

Method of depositing a catalyst on a fuel cell electrode

DOEpatents

Dearnaley, Geoffrey; Arps, James H.

2000-01-01

Fuel cell electrodes comprising a minimal load of catalyst having maximum catalytic activity and a method of forming such fuel cell electrodes. The method comprises vaporizing a catalyst, preferably platinum, in a vacuum to form a catalyst vapor. A catalytically effective amount of the catalyst vapor is deposited onto a carbon catalyst support on the fuel cell electrode. The electrode preferably is carbon cloth. The method reduces the amount of catalyst needed for a high performance fuel cell electrode to about 0.3 mg/cm.sup.2 or less.

Reaction pathways involved in CH4 conversion on Pd/Al2O3 catalysts : TAP as a powerful tool for the elucidation of the effective role of the metal/support interface

NASA Astrophysics Data System (ADS)

Granger, Pascal

2016-02-01

Temporal Analysis of Products (TAP) reactor offers an alternative to draw direct structure/activity relationships checked on Natural Gas-fuelled Vehicle (NGV) catalysts Determination of accurate kinetic constants for methane adsorption from single pulse experiments and subsequent investigation of sequential surface reactions from alternative CH4/O2 pulse experiments provides a straightforward visualization of the involvement of the metal/support interface on freshly-prepared catalysts and the loss of this effect on aged single palladium based catalysts.

Natrolite zeolite supported copper nanoparticles as an efficient heterogeneous catalyst for the 1,3-diploar cycloaddition and cyanation of aryl iodides under ligand-free conditions.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Khalaj, Mehdi

2015-09-01

In this paper, we report the preparation of Natrolite zeolite supported copper nanoparticles as a heterogeneous catalyst for 1,3-diploar cycloaddition and synthesis aryl nitriles from aryl iodides under ligand-free conditions. The catalyst was characterized using XRD, SEM, TEM, EDS and TG-DTA. The experimental procedure is simple, the products are formed in high yields and the catalyst can be recycled and reused several times without any significant loss of catalytic activity. Copyright © 2015 Elsevier Inc. All rights reserved.

Silica supported palladium nanoparticles for the decarboxylation of high-acid feedstocks: Design, deactivation and regeneration

NASA Astrophysics Data System (ADS)

Ping, Eric Wayne

2011-12-01

The major goals of this thesis were to (1) design and synthesize a supported catalyst with well-defined monodisperse palladium nanoparticles evenly distributed throughout an inorganic oxide substrate with tunable porosity characteristics, (2) demonstrate the catalytic activity of this material in the decarboxylation of long chain fatty acids and their derivatives to make diesel-length hydrocarbons, (3) elucidate the deactivation mechanism of supported palladium catalysts under decarboxylation conditions via post mortem catalyst characterization and develop a regeneration methodology thereupon, and (4) apply this catalytic system to a real low-value biofeedstock. Initial catalyst designs were based on the SBA-15 silica support, but in an effort to maximize loading and minimize mass transfer limitations, silica MCF was synthesized as catalyst support. Functionalization with various silane ligands yielded a surface that facilitated even distribution of palladium precursor salts throughout the catalyst particle, and, after reduction, monodisperse palladium nanoparticles approximately 2 nm in diameter. Complete characterization was performed on this Pd-MCF catalyst. The Pd-MCF catalyst showed high one-time activity in the decarboxylation of fatty acids to hydrocarbons in dodecane at 300°C. Hydrogen was found to be an unnecessary reactant in the absence of unsaturations, but was required in their presence---full hydrogenation of the double bonds occurs before any decarboxylation can take place. The Pd-MCF also exhibited good activity for alkyl esters and glycerol, providing a nice hypothetical description of a stepwise reaction pathway for catalytic decarboxylation of acids and their derivatives. As expected, the Pd-MCF catalyst experienced severe deactivation after only one use. Substantial effort was put into elucidating the nature of this deactivation via post mortem catalyst characterization. H2 chemisorption confirmed a loss of active surface area, but TEM and EXAFS ruled out morphological alterations in the supported nanoparticles. Significant decreases in pore volume and surface area via N2 physisorption put deposition under suspicion and TGA confirmed the presence of organic species in the material. Initial attempts to remove the deposits via calcination were successful, but at the expense of severe nanoparticle growth. GC-MS, NMR and FT-IR helped speciate the deposition, mainly confirming the presence of residual reactant acid. A regeneration scheme was developed to remove these compounds, and subsequent catalyst reuses exhibited high decarboxylation activity. Finally, the Pd-MCF catalyst was applied to a real feedstock: a wastewater-derived brown grease from a poultry rendering facility. Attempts at decarboxylating the raw material failed, so efforts to polish the material via dewaxing and degumming were undertaken. The treatments were able to optimize a three-phase separation, and the resultant polished brown grease was successfully decarboxylated to diesel-length hydrocarbons with high conversions and selectivities.

Steam reforming of n-hexane on pellet and monolithic catalyst beds. A comparative study on improvements due to heat transfer

NASA Technical Reports Server (NTRS)

1981-01-01

Monolithic catalysts with higher available active surface areas and better thermal conductivity than conventional pellets beds, making possible the steam reforming of fuels heavier than naphtha, were examined. Performance comparisons were made between conventional pellet beds and honeycomb monolith catalysts using n-hexane as the fuel. Metal-supported monoliths were examined. These offer higher structural stability and higher thermal conductivity than ceramic supports. Data from two metal monoliths of different nickel catalyst loadings were compared to pellets under the same operating conditions. Improved heat transfer and better conversion efficiencies were obtained with the monolith having higher catalyst loading. Surface-gas interaction was observed throughout the length of the monoliths.

High performance, high durability non-precious metal fuel cell catalysts

DOEpatents

Wood, Thomas E.; Atanasoski, Radoslav; Schmoeckel, Alison K.

2016-03-15

This invention relates to non-precious metal fuel cell cathode catalysts, fuel cells that contain these catalysts, and methods of making the same. The fuel cell cathode catalysts are highly nitrogenated carbon materials that can contain a transition metal. The highly nitrogenated carbon materials can be supported on a nanoparticle substrate.

Non-conventional Pt-Cu alloy/carbon paper electrochemical catalyst formed by electrodeposition using hydrogen bubble as template

NASA Astrophysics Data System (ADS)

Kim, Youngkwang; Lee, Hyunjoon; Lim, Taeho; Kim, Hyun-Jong; Kwon, Oh Joong

2017-10-01

With emerging stability issues in fuel cell technology, a non-conventional catalyst not supported on carbon materials has been highlighted because it can avoid negative influences of carbon support materials on the stability, such as carbon corrosion. The nanostructured thin film catalyst is representative of non-conventional catalysts, which shows improved stability, enhanced mass specific activity, and fast mass transfer at high current densities. However, the nanostructured thin film catalyst usually requires multi-step processes for fabrication, making its mass production complex and irreproducible. We introduce a Pt-Cu alloy nanostructured thin film catalyst, which can be simply prepared by electrodeposition. By using hydrogen bubbles as a template, a three-dimensional free-standing foam of Cu was electrodeposited directly on the micro-porous layer/carbon paper and it was then displaced with Pt by simple immersion. The structure characterization revealed that a porous thin Pt-Cu alloy catalyst layer was successfully formed on the micro-porous layer/carbon paper. The synthesized Pt-Cu alloy catalyst exhibited superior durability compared to a conventional Pt/C in single cell test.

Hydrogen generation from catalytic hydrolysis of alkaline sodium borohydride solution using attapulgite clay-supported Co-B catalyst

NASA Astrophysics Data System (ADS)

Tian, Hongjing; Guo, Qingjie; Xu, Dongyan

An attapulgite clay-supported cobalt-boride (Co-B) catalyst used in portable fuel cell fields is prepared in this paper by impregnation-chemical reduction method. The cost of attapulgite clay is much lower compared with some other inert carriers, such as activated carbon and carbon nanotube. Its microstructure and catalytic activity are analyzed in this paper. The effects of NaOH concentration, NaBH 4 concentration, reacting temperature, catalyst loadings and recycle times on the performance of the catalysts in hydrogen production from alkaline NaBH 4 solutions are investigated. Furthermore, characteristics of these catalysts are carried out in SEM, XRD and TEM analysis. The high catalytic activity of the catalyst indicates that it is a promising and practical catalyst. Activation energy of hydrogen generation using such catalysts is estimated to be 56.32 kJ mol -1. In the cycle test, from the 1st cycle to the 9th cycle, the average hydrogen generation rate decreases gradually from 1.27 l min -1 g -1 Co-B to 0.87 l min -1 g -1 Co-B.

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15.

PubMed

Zhang, Lei; Abbenhuis, Hendrikus C L; Gerritsen, Gijsbert; Bhriain, Nollaig Ní; Magusin, Pieter C M M; Mezari, Brahim; Han, Wei; van Santen, Rutger A; Yang, Qihua; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380 m2 g-1) and pore volume (>or==0.46 cm3 g-1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert-butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites.

Highly Active and Stable Pt–Pd Alloy Catalysts Synthesized by Room‐Temperature Electron Reduction for Oxygen Reduction Reaction

PubMed Central

Wang, Wei; Wang, Zongyuan; Wang, Jiajun; Zhong, Chuan‐Jian

2017-01-01

Carbon‐supported platinum (Pt) and palladium (Pd) alloy catalyst has become a promising alternative electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this work, the synthesis of highly active and stable carbon‐supported Pt–Pd alloy catalysts is reported with a room‐temperature electron reduction method. The alloy nanoparticles thus prepared show a particle size around 2.6 nm and a core–shell structure with Pt as the shell. With this structure, the breaking of O–O bands and desorption of OH are both promoted in electrocatalysis of ORR. In comparison with the commercial Pt/C catalyst prepared by conventional method, the mass activity of the Pt–Pd/C catalyst for ORR is shown to increase by a factor of ≈4. After 10 000‐cycle durability test, the Pt–Pd/C catalyst is shown to retain 96.5% of the mass activity, which is much more stable than that of the commercial Pt/C catalyst. PMID:28435780

Effect of plasma treatments to graphite nanofibers supports on electrochemical behaviors of metal catalyst electrodes.

PubMed

Lee, Hochun; Jung, Yongju; Kim, Seok

2012-02-01

In the present work, we had studied the graphite nanofibers as catalyst supports after a plasma treatment for studying the effect of surface modification. By controlling the plasma intensity, a surface functional group concentration was changed. The nanoparticle size, loading efficiency, and catalytic activity were studied, after Pt-Ru deposition by a chemical reduction. Pt-Ru catalysts deposited on the plasma-treated GNFs showed the smaller size, 3.58 nm than the pristine GNFs. The catalyst loading contents were enhanced with plasma power and duration time increase, meaning an enhanced catalyst deposition efficiency. Accordingly, cyclic voltammetry result showed that the specific current density was increased proportionally till 200 W and then the value was decreased. Enhanced activity of 40 (mA mg(-1)-catalyst) was accomplished at 200 W and 180 sec duration time. Consequently, it was found that the improved electroactivity was originated from the change of size or morphology of catalysts by controlling the plasma intensity.

Activity Tests of Macro-Meso Porous Catalysts over Metal Foam Plate for Steam Reforming of Bio-Ethanol.

PubMed

Park, No-Kuk; Jeong, Yong Han; Kang, Misook; Lee, Tae Jin

2018-09-01

The catalytic activity of a macro-mesoporous catalyst coated on a metal foam plate in the reforming of bio-ethanol to synthesis gas was investigated. The catalysts were prepared by coating a support with a noble metal and transition metal. The catalytic activity for the production of synthetic gas by the reforming of bio-ethanol was compared according to the support material, reaction temperature, and steam/carbon ratio. The catalysts coated on the metal foams were prepared using a template method, in which macro-pores and meso-pores were formed by mixing polymer beads. In particular, the thermodynamic equilibrium composition of bio-ethanol reforming with the reaction temperature and steam/carbon ratio to produce synthetic gas was examined using the HSC (Enthalpy-Entropy-Heat capacity) chemistry program in this study. The composition of hydrogen and carbon monoxide in the reformate gas produced by steam reforming over the Rh/Ni-Ce-Zr/Al2O3-based pellet type catalysts and metal foam catalysts that had been coated with the Rh/Al-Ce-Zr-based catalysts was investigated by experimental activity tests. The activity of the metal foam catalyst was higher than that of the pellet type catalyst.

The application of aberration-corrected electron microscopy to the characterization of gold-based catalysts

NASA Astrophysics Data System (ADS)

Herzing, Andrew A.

Electron microscopy has long been used to study the morphology of heterogeneous catalysts. Recent advances in electron optics now allow for the correction of the inherent spherical aberration (Cs) produced by the objective lens in the scanning transmission electron microscope (STEM, resulting in a significantly improved spatial resolution as well as the ability to use a much larger probe-current than was previously possible. In this thesis, the combination of high-angle annular dark-field (HAADF) imaging and microanalysis by x-ray energy dispersive spectroscopy (XEDS) in an aberration-corrected STEM has been applied for the first time to the characterization of gold-based heterogeneous catalysts. Multi-variate statistical analysis (MSA) has been employed in order to further improve the STEM-XEDS spectrum image data acquired with this technique. In addition, supplemental analysis using electron-energy loss spectroscopy (EELS) and energy-filtered transmission electron microscopy (EFTEM) in an aberration-corrected instrument has also been attempted. These techniques have proven extremely valuable in providing complimentary information to more traditional catalyst characterization techniques such as x-ray photoelectron spectroscopy and x-ray diffraction in four specific problems relating to catalysis. Firstly, the atomic-scale resolution of Cs-corrected HAADF imaging has been utilized to study Au/FeOx catalysts in order to determine the size and structure of the Au clusters present on the support surface. It was discovered that, while both inactive and active catalysts for low-temperature CO oxidation contained large Au particles (> 5 nm) and individual Au atoms, the active catalyst also contained sub-nm clusters comprised of only a few Au atoms. Secondly, novel CeO2 support materials for Au and Au-Pd catalysts were synthesized by precipitation with supercritical CO2. These supports were found to produce significantly more active catalysts than those based on CeO2 prepared using more traditional methods. The combination of STEM-HAADF imaging and XEDS mapping has been used to characterize these catalysts and a strong correlation between the catalytic activity and the enhanced degree of metal dispersion over the support is demonstrated. Thirdly, a systematic series of Au-Pd/Al2O3 catalysts has been studied in order to characterize the effects of various heat treatments on the development of core-shell morphologies within the bi-metallic particles and its subsequent effect on their catalytic performance for H2O 2 synthesis. STEM-XEDS spectrum imaging was employed in order to determine the degree of alloying and segregation behavior within the individual Au-Pd particles as a function of calcination/reduction temperature. It was found that the as prepared catalyst contained homogeneous Au-Pd alloy particles and that a Pd-rich shell/Au-rich core morphology gradually developed upon calcination. Subsequent reduction of the catalyst caused a large fraction of the particles to invert and form Pd-rich core/Au-rich shell structures. These changes are related to both the activity and stability of the catalyst. Finally, the washing of activated carbon support materials in acid was found to be extremely beneficial for producing Au-Pd catalysts for the direct synthesis of H2O2. STEM-HAADF imaging revealed that the acid-washing treatment increased the dispersion of the metal on the carbon supports. Aberration-corrected STEM-XEDS spectrum imaging demonstrated a strong size dependence of the Au-Pd particle composition. Crucially, the acid-washing pre-treatment enhanced the alloying of Au and Pd by suppressing the formation of large (> 25 nm) Au-rich particles. In summary, the application of aberration-corrected HAADF imaging and STEM-XEDS spectrum imaging to the characterization of Au-based catalysts has enhanced the understanding of the structural and chemical features that determine their catalytic behavior. Specifically, they have allowed us to achieve the following: (a) image individual metal atoms and clusters of just a few atoms dispersed in a real, high surface area catalyst, (b) detect and follow the development of core-shell structures in Au-Pd bi-metallic catalysts, (c) determine composition/size correlations in Au-Pd catalysts, (d) detect minor alloying elements in bi-metallic catalysts, (e) and chemically map atomic or near atomic dispersions of metals on oxide supports.

Molybdenum sulfide/carbide catalysts

DOEpatents

Alonso, Gabriel [Chihuahua, MX; Chianelli, Russell R [El Paso, TX; Fuentes, Sergio [Ensenada, MX; Torres, Brenda [El Paso, TX

2007-05-29

The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

Evaluation of mechanical properties in metal wire mesh supported selective catalytic reduction (SCR) catalyst structures

NASA Astrophysics Data System (ADS)

Rajath, S.; Siddaraju, C.; Nandakishora, Y.; Roy, Sukumar

2018-04-01

The objective of this research is to evaluate certain specific mechanical properties of certain stainless steel wire mesh supported Selective catalytic reduction catalysts structures wherein the physical properties of the metal wire mesh and also its surface treatments played vital role thereby influencing the mechanical properties. As the adhesion between the stainless steel wire mesh and the catalyst material determines the bond strength and the erosion resistance of catalyst structures, surface modifications of the metal- wire mesh structure in order to facilitate the interface bonding is therefore very important to realize enhanced level of mechanical properties. One way to enhance such adhesion properties, the stainless steel wire mesh is treated with the various acids, i.e., chromic acid, phosphoric acid including certain mineral acids and combination of all those in various molar ratios that could generate surface active groups on metal surface that promotes good interface structure between the metal- wire mesh and metal oxide-based catalyst material and then the stainless steel wire mesh is dipped in the glass powder slurry containing some amount of organic binder. As a result of which the said catalyst material adheres to the metal-wire mesh surface more effectively that improves the erosion profile of supported catalysts structure including bond strength.

Nanosized CuO and ZnO catalyst supported on titanium chip for conversion of carbon dioxide to methyl alcohol.

PubMed

Seo, Hyeong-Seok; Park, Chul-Min; Kim, Ki-Joong; Jeong, Woon-Jo; Chung, Min-Chul; Jung, Sang-Chul; Kim, Sang-Chai; Ahn, Ho-Geun

2013-08-01

In order to reutilize spent metallic titanium chips (TC) as catalyst support or photocatalytic materials, the surface of the TC was modified by thermal treatment under air atmosphere. TC-supported nanosized CuO and ZnO catalysts were prepared by impregnation (IMP) and co-precipitation (CP) method, respectively. The catalytic activity for CO2 hydrogenation to CH3OH was investigated using a flow-typed reactor under various reaction pressures. The crystals of CuO and ZnO was well formed on TC. CO2 conversion, CH3OH selectivity, and CH3OH yield were obtained as a function of time on stream over CuO-ZnO/TC catalysts. Conversion of CO2 to CH3OH over CuO-ZnO/TC catalyst by CP method and CuO/ZnO/TC catalyst by IMP method were ca. 16% and ca. 12%, respectively. Conversion of CO2 over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in the range of 15-30 atm. Maximum selectivity and yield to CH3OH over CuO-ZnO/TC at 250 degrees C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively.

Towards the preparation of realistic model Ziegler-Natta catalysts: XPS study of the MgCl 2/TiCl 4 interaction with flat SiO 2/Si(1 0 0)

NASA Astrophysics Data System (ADS)

Siokou, Angeliki; Ntais, Spyridon

2003-08-01

Despite of the wide use of supported Ti based Ziegler-Natta catalysts in the olefin polymerization industry, questions concerning the role of each one of the catalyst components in the polymerization process, have not found a satisfactory answer yet. This is mainly because of the high sensitivity of these systems to oxygen and atmospheric moisture that makes their study in an atomic level rather complicated. Realistic surface science models of the pre-activated SiO 2 supported MgCl 2/TiCl 4 and TiCl 4 Ziegler-Natta catalysts were prepared by spin coating on flat conductive SiO 2/Si(1 0 0) supports under inert atmosphere. This preparation technique resembles the wet chemical impregnation which is the industrial method of the catalyst preparation. XPS analysis showed that the catalyst precursor anchors on the silica surface through bonding of the Ti atoms with surface silanes or siloxanes, while Mg is attached to the Ti through chlorine bridges. Thermal treatment of the catalysts at 723 K leads to total Cl desorption when MgCl 2 is not present while a significant amount of the Ti atoms is reduced to the Ti 3+ state.

Effect of carbon supports on RhRe bifunctional catalysts for selective hydrogenolysis of tetrahydropyran-2-methanol

DOE PAGES

Karanjkar, Pranav U.; Burt, Samuel P.; Chen, Xiaoli; ...

2016-09-12

Tetrahydropyran-2-methanol undergoes selective C–O–C hydrogenolysis to produce 1,6-hexanediol using a bifunctional RhRe (reducible metal with an oxophilic promoter) catalyst supported on Vulcan XC-72 carbon (VXC) with >90% selectivity. This RhRe/VXC catalyst is stable over 40 h of reaction in a continuous flow fixed bed reactor. The hydrogenolysis activity of RhRe/VXC is two orders-of-magnitude higher than that of RhRe supported on Norit Darco 12X40 activated carbon (NDC). STEM–EDS analysis reveals that, compared to the RhRe/VXC catalyst, the Re and Rh component metals are segregated on the surface of the low activity RhRe/NDC catalyst, suggesting that Rh and Re in close proximitymore » (“bimetallic” particles) are required for an active hydrogenolysis catalyst. Differences in metal distribution on the carbon surfaces are, in turn, linked to the properties of the carbons: NDC has both a higher surface area and surface oxygen content. Thus, the low areal density of Rh and Re precursors on the high area NDC and/or interactions of the precursors with its O functional groups may interfere with the formation of the bimetallic species required for an active catalyst.« less

Synthesis and Characterization of Mixed-Conducting Corrosion Resistant Oxide Supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramani, Vijay K.

An extensive search and evaluation of electrochemically stable catalyst supports (including metal oxides like RuO2-SiO2, RuO2-TiO2, and ITO was perfomed during the 4 years of the project. The suports were also catalyzed by deposition of Pt and tested for its performance and electrochemical stability in RDE and fuel cell experiments. For testing the electrochemical stability and fuel cell performance of the catalysts and supports, we have employed the protocols in use at the Department of Energy and Nissan Technological Center North America (NTCNA). The use of such procedures allows a precise and reproducible estimation of the performance and stability ofmore » the materials and permits comparisons among laboratories and DOE funded projects. RuO2-SiO2 catalyst supports showed no loss in surface area during start-stop stability tests that were performed by cycling the electrode potential between 0 V to 1.8 V for 1000 cycles. Catalyzed support (40% Pt/RuO2-SiO2; 1:1 mole ratio) were tested in a PEFC, resulting in a current density of 750 mA/cm2 at 0.6 Volts, and a maximum power density of 570 mW/cm2. Measurements were conducted at 80 ºC with 75% relative humidity of the inlet gases (H2/O2); Pt loadings were 0.4 mg/cm2 at the cathode and 0.2 mg/cm2 at the anode. Start-stop stability tests for support and catalyzed support performed in RDE and PEFC set-ups have confirmed RuO2-TiO2 support stability. The beginning of life performance was exactly equal to end of life performance (in an MEA that has been subjected to severe start-stop cycling for 10,000 start/stop cycles between 1 V to 1.5 V). This result was in sharp contrast to baseline Pt/C catalyst that showed significant performance deterioration after accelerated stability tests. The Pt/TRO showed minimal loss in performance upon exposure to start-stop cycles. The loss in cell voltage at 1 A/cm2 at 100% RH was almost 700 mV for Pt/C whereas it was only ca. 15 mV for Pt/TRO. 40% RH data (of inlet gases) revealed a similar trend in terms of stability – exceptional stability for Pt/TRO as opposed to very poor stability for Pt/HSAC. These observations were attributed to the much higher stability of the TRO support compared to Carbon. The carbon dioxide concentration in the cathode exit stream during the accelerated degradation test with Pt/TRO (start-stop protocol) was extremely low (between 3 to 10 ppm of CO2). In contrast, the CO2 emission levels from a conventional Pt/C catalyst were found to be approx. 200 ppm. This observation was a clear indicator that the main source of carbon being oxidized to carbon dioxide in an MEA was the carbon catalyst support, and not the gas diffusion layer or the graphite flow fields. Indium tin oxide (ITO) was also evaluated as a catalyst support for PEFCs. Pt/ITO was very stable under start-up/shutdown accelerated degradation protocol (RDE tests in perchloric acid). The ECSA change was less than 4% over 10,000 cycles. The load cycling accelerated protocol (from 0.6 to 0.95 V vs. RHE) resulted in a loss of approximately 34% of the initial ECSA after 10,000 cycles. However, fuel cell testing resulted in a very low performing catalyst. XPS spectroscopy was employed to investigate the changes in the catalysts occuring during fuel cell operation. It was observed a shift of In 3d5/2 and In 3d3/2 peaks towards higher binding energies. This can be explained by the formation of hydroxides or oxy-hydroxides in the surface of the catalyst. O1s spectrum for Pt/ITO catalyst after being operated in the fuel cell, also confirmed the formation of significant amounts of surface hydroxides (12 to 16%). The presence of surface hydroxides in the catalyst increased the electrode resistivity affecting fuel cell performance. NTCNA performed a detailed analysis of transport phenomena (reactants and products to/from the Pt active sites) in both commercial catalyst and Pt/RTO (in order to have a better understanding at the basic level). The proton resistance (Rionomer) in Pt/C and Pt/RTO cathode catalyst layers were 150 and 12 mΩ-cm2, respectively. Pt/RTO catalyst layer has about an order or magnitude lower proton transfer resistance than Pt/C catalyst layer. Since the ionomer/support ratio that was used in formulating the ink for both catalysts was the same (0.9), it is expected that the volumetric coverage of ionomer of both catalysts will be significantly different due to the disparity in the surface areas (Pt/C had ~ 800 m2/g, while Pt/RTO had ~ 50 m2/g). The differences in the ionomer volumetric coverage and the ionomer film thickness may explain the significantly higher proton conductivity in the Pt/RTO catalyst layer when compared to Pt/HSAC. It is therefore very important to optimize the ionomer loadings when synthesizing new catalyst supports (and never rely on values for carbon-based commercial catalysts). Finally, NTCNA has elaborated a cost model for non-carbon support materials considering their durability benefits. Material costs for production of Pt/ RuO2-TiO2 electrodes were compared to Pt/C. RuO2-TiO2 support was more expensive than carbon but the total material cost was still dominated by platinum cost. Though ruthenium is considered a precious metal, its cost is far less than platinum. It should also be noted that ruthenium only makes up 38% of the mass of the support, while the rest is inexpensive TiO2. After considering the durability advantages of Pt/RTO, cost model showed that even with almost double the Pt loading (0.35 vs 0.18 mgPt/cm2), Pt/RTO ($22.7/kWnet) is only slightly more expensive than Pt/C ($21.9/kWnet).« less

MicroChannel Reactors for ISRU Applications Using Nanofabricated Catalysts

NASA Astrophysics Data System (ADS)

Carranza, Susana; Makel, Darby B.; Vander Wal, Randall L.; Berger, Gordon M.; Pushkarev, Vladimir V.

2006-01-01

With the new direction of NASA to emphasize the exploration of the Moon, Mars and beyond, quick development and demonstration of efficient systems for In-Situ Resources Utilization (ISRU) is more critical and timely than ever before. Affordable planning and execution of prolonged manned space missions depend upon the utilization of local resources and the waste products which are formed in manned spacecraft and surface bases. This paper presents current development of miniaturized chemical processing systems that combine microchannel reactor design with nanofabricated catalysts. Carbon nanotubes (CNT) are used to produce a nanostructure within microchannel reactors, as support for catalysts. By virtue of their nanoscale dimensions, nanotubes geometrically restrict the catalyst particle size that can be supported upon the tube walls. By confining catalyst particles to sizes smaller than the CNT diameter, a more uniform catalyst particle size distribution may be maintained. The high dispersion permitted by the vast surface area of the nanoscale material serves to retain the integrity of the catalyst by reducing sintering or coalescence. Additionally, catalytic efficiency increases with decreasing catalyst particle size (reflecting higher surface area per unit mass) while chemical reactivity frequently is enhanced at the nanoscale. Particularly significant is the catalyst exposure. Rather than being confined within a porous material or deposited upon a 2-d surface, the catalyst is fully exposed to the reactant gases by virtue of the nanofabricated support structure. The combination of microchannel technology with nanofabricated catalysts provides a synergistic effect, enhancing both technologies with the potential to produce much more efficient systems than either technology alone. The development of highly efficient microchannel reactors will be applicable to multiple ISRU programs. By selection of proper nanofabricated catalysts, the microchannel reactors can be designed for the processes that generate the most benefit for each mission, from early demonstration missions to long term settlements.

3D Polymer Hydrogel for High-Performance Atomic Fe and Mn Catalysts for Oxygen Reduction in Challenging Acids

NASA Astrophysics Data System (ADS)

Qiao, Zhi

Current platinum group metal (PGM)-free carbon nanocomposite catalysts for the oxygen reduction reaction (ORR) in acidic electrolyte often suffer from rapid degradation associated with carbon corrosion due to the use of large amount of the amorphoous carbon black supports. Here, we developed a new concept of using freestanding 3D hydrogel to design support-free Fe-N-C catalysts. A 3D polyaniline (PANI)-based hydrogel approach was used for preparing a new type of single atomic iron site-rich catalyst, which has exhibited exceptionally enhanced activity and stability compared to conventional Fe-N-C catalysts supported on amorphous carbon blacks. The achieved performance metric on the hydrogel PANI-Fe catalysts is one of the best ever reported PGM-free catalysts, reaching a half-wave potential up to 0.83 V vs. RHE and only leaving 30 mV gap with Pt/C catalysts (60mugPt/cm 2) in challenging acidic media. Remarkable ORR stability was accomplished as well on the same catalyst evidenced by using harsh potential cycling tests. The well dispersion of atomic iron into partially graphitized carbon, featured with dominance of micropores and porous network structures, is capable of accommodating increased number of active sites, strengthening local bonding among iron, nitrogen and carbon, and facilitating mass transfer. On the other hand, in order to decrease the produced Fenton reagent, which will oxidize the proton exchange membrane and ionomer in membrane electrode assembly (MEA), we produce Mn-based catalysts by this novel hydrogel method. This is the first time that Mn-based catalysts can show such outstanding performance in acid media, whose half-wave potential is up to 0.80 V vs. RHE. The work related to the performance improvement is still in processing. We believe the 3D polymer hydrogel approach would be a new pathway to advance PGM-free catalysts.

Nano-catalysts: Bridging the gap between homogeneous and heterogeneous catalysis

EPA Science Inventory

Functionalized nanoparticles have emerged as sustainable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. We envisioned a catalyst system, which can bridge the homogenous and heterogeneous system. Postsynthetic surface modifica...

Characteristics of polyaniline cobalt supported catalysts for epoxidation reactions.

PubMed

Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

2014-01-01

A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established.

Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

PubMed Central

Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

2014-01-01

A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established. PMID:24701183

Selective alkane activation with single-site atoms on amorphous support

DOEpatents

Hock, Adam S.; Schweitzer, Neil M.; Miller, Jeffrey T.; Hu, Bo

2015-11-24

The present invention relates generally to catalysts and methods for use in olefin production. More particularly, the present invention relates to novel amorphously supported single-center, Lewis acid metal ions and use of the same as catalysts.

Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

DOEpatents

Pierantozzi, R.

1985-04-02

A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

DOEpatents

Pierantozzi, Ronald

1985-01-01

A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

Catalysis on Mo(CO)/sub 6/-derived supported molybdenum catalysts: CO oxidation with N/sub 2/O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazusaka, A.; Howe, R.F.

1988-05-01

The catalytic nature of Mo(CO)/sub 6/ supported on ..gamma..-Al/sub 2/O/sub 3/, KOH-doped ..gamma..-Al/sub 2/O/sub 3/, and HY-zeolite was investigated in CO oxidation with N/sub 2/O in comparison with that of a conventional partially reduced MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ catalyst. Kinetic parameters of this reaction were obtained in the range 0 to 100/sup 0/C; the rate law r = kP/sub N/sub 2/O//sup 1/P/sub CO//sup 0/ was found on all catalysts, and the activation energy was estimated to be 9.1 kcal/mol on the Mo(CO)/sub 6/-derived catalysts and 7.1 kcal/mol on the partially reduced MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ catalyst. Maximum catalytic activities weremore » obtained by activating the Mo(CO)/sub 6/-derived catalysts at 400/sup 0/C. To obtain similar activity on the MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ catalyst, it was necessary to reduce at 600/sup 0/C. The former catalysts were deactivated on repeating the reaction. On the basis of these results and those of ESR studies through the activation or deactivation process, an active site on the Mo(CO)/sub 6/-derived catalysts has been proposed. Also, clear IR absorption bands due to chemisorbed CO and N/sub 2/O species were observed on the HY-zeolite-supported catalysts. A reaction mechanism is proposed from the kinetic and IR spectroscopic results.« less

Direct synthesis of few-layer graphene supported platinum nanocatalyst for methanol oxidation

NASA Astrophysics Data System (ADS)

Tan, Hong; Ma, Xiaohui; Sheng, Leimei; An, Kang; Yu, Liming; Zhao, Hongbin; Xu, Jiaqiang; Ren, Wei; Zhao, Xinluo

2014-11-01

High-crystalline few-layer graphene supported Pt nanoparticles have been synthesized by arc discharge evaporation of carbon electrodes containing Pt element. A high-temperature treatment under hydrogen atmosphere has been carried out to obtain a new type of Pt/graphene catalyst for methanol oxidation in direct methanol fuel cell. The morphology and structure characterizations of as-grown few-layer graphene supported Pt nanoparticles and Pt/graphene catalysts have been studied by Raman spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy. Cyclic voltammograms and chronoamperometric curves show that our present Pt/graphene catalysts have larger current density for methanol oxidation, higher tolerance to carbon monoxide poisoning, and better stability during the operating procedure, compared to commercial Pt/C catalysts.

CO oxidation studies over supported noble metal catalysts and single crystals: A review

NASA Technical Reports Server (NTRS)

Boecker, Dirk; Gonzalez, Richard D.

1987-01-01

The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

Advanced cathode materials for polymer electrolyte fuel cells based on pt/ metal oxides: from model electrodes to catalyst systems.

PubMed

Fabbri, Emiliana; Pătru, Alexandra; Rabis, Annett; Kötz, Rüdiger; Schmidt, Thomas J

2014-01-01

The development of stable catalyst systems for application at the cathode side of polymer electrolyte fuel cells (PEFCs) requires the substitution of the state-of-the-art carbon supports with materials showing high corrosion resistance in a strongly oxidizing environment. Metal oxides in their highest oxidation state can represent viable support materials for the next generation PEFC cathodes. In the present work a multilevel approach has been adopted to investigate the kinetics and the activity of Pt nanoparticles supported on SnO2-based metal oxides. Particularly, model electrodes made of SnO2 thin films supporting Pt nanoparticles, and porous catalyst systems made of Pt nanoparticles supported on Sb-doped SnO2 high surface area powders have been investigated. The present results indicate that SnO2-based supports do not modify the oxygen reduction reaction mechanism on the Pt nanoparticle surface, but rather lead to catalysts with enhanced specific activity compared to Pt/carbon systems. Different reasons for the enhancement in the specific activity are considered and discussed.

Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

NASA Technical Reports Server (NTRS)

Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

1993-01-01

Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

A gallium phosphide high-temperature bipolar junction transistor

NASA Technical Reports Server (NTRS)

Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

1981-01-01

Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

Laser ablation synthesis of arsenic-phosphide Asm Pn clusters from As-P mixtures. Laser desorption ionisation with quadrupole ion trap time-of-flight mass spectrometry: The mass spectrometer as a synthesizer.

PubMed

Kubáček, Pavel; Prokeš, Lubomír; Pamreddy, Annapurna; Peña-Méndez, Eladia María; Conde, José Elias; Alberti, Milan; Havel, Josef

2018-05-30

Only a few arsenic phosphides are known. A high potential for the generation of new compounds is offered by Laser Ablation Synthesis (LAS) and when Laser Desorption Ionization (LDI) is coupled with simultaneous Time-Of-Flight Mass Spectrometry (TOFMS), immediate identification of the clusters can be achieved. LAS was used for the generation of arsenic phosphides via laser ablation of phosphorus-arsenic mixtures while quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to acquire the mass spectra. Many new As m P n ± clusters (479 binary and 369 mono-elemental) not yet described in the literature were generated in the gas phase and their stoichiometry determined. The likely structures for some of the observed clusters arbitrary selected (20) were computed by density functional theory (DFT) optimization. LAS is an advantageous approach for the generation of new As m P n clusters, while mass spectrometry was found to be an efficient technique for the determination of cluster stoichiometry. The results achieved might inspire the synthesis of new materials. Copyright © 2018 John Wiley & Sons, Ltd.

Uranium distribution in pseudowollastonite slag from a phosphorus furnace

USGS Publications Warehouse

Young, Edward; Altschuler, Zalman S.

1956-01-01

Silicate slag from the Victor Chemical Company phosphorus furnace at Tarpon Springs, Fla., has been found to consist essentially of pseudowollastonite, α-CaSiO3. The first-formed crystals are euhedral laths which form a mesh making up most of the slag. As the slag continues to solidify, its composition changes slightly and more equant, subhedral crystals of pseudowollastonite are deposited within the framework of the earlier material. Finally, anherdral masses of fibrous, poorly crystallized material are deposited in the remaining pore spaces which are not always completely filled. Spherules of iron phosphide, Fe2P, occur very sparsely in the slag as inclusions from the immiscible iron phosphide melt. Uranium content increases in the later crystal products of the slag, and by heavy-liquid fractionation it has been possible to segregate partially the phases and to obtain a fourfold concentration of uranium in 5 percent of the material and a twofold concentration in 30 percent of the material. Nuclear-emulsion studies indicate that the last phases of the silicate slag are actually eight times as radioactive as the early phases. In addition, the iron phosphide spherules are comparably enriches in uranium.

General One-Pot Synthesis of Transition-Metal Phosphide/Nitrogen-Doped Carbon Hybrid Nanosheets as Ultrastable Anodes for Sodium-Ion Batteries.

PubMed

Li, Jingjing; Shi, Liang; Gao, Jingyu; Zhang, Genqiang

2018-01-26

Sodium-ion batteries (SIBs) have been considered as promising energy storage devices in grid-level applications, owing to their largely reduced cost compared with that of lithium-ion batteries. However, the practical application of SIBs has been seriously hindered because of the lack of appropriate anode materials, limited by the thermodynamics perspective, which is one of the central task at current stage. Herein, we have developed a general one-pot strategy for the synthesis of transition-metal phosphide (TMP) based hybrid nanosheets composed of carbon-coated TMP nanoparticles anchored to the surface of nitrogen-doped carbon nanosheets. This facile and cost-effective method is quite universal and holds potential to be further extended to other metal phosphide materials. Significantly, the hybrid nanosheet electrode possesses excellent sodium storage properties as anodes for SIBs, including high specific capacity, an ultra-long cycle life and a remarkable rate performance. This work makes a significant contribution to not only the synthetic methodology of TMP-carbon two-dimensional hybrid nanostructures, but also the application of TMP-based anodes for high-energy SIBs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support

NASA Technical Reports Server (NTRS)

Klettlinger, Jennifer Lindsey Suder

2012-01-01

The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the active site density; on the other hand, by increasing the size of the cobalt clusters, there is less likelihood of forming oxidized cobalt complexes (cobalt aluminate) during Fischer-Tropsch synthesis. Thus, from the standpoint of stability, improving the extent of reduction while increasing the particle size slightly may be beneficial for maintaining the sites, even if there is a slight decrease in overall initial active site density.

Supported fischer-tropsch catalyst and method of making the catalyst

DOEpatents

Dyer, Paul N.; Pierantozzi, Ronald; Withers, Howard P.

1987-01-01

A Fischer-Tropsch catalyst and a method of making the catalyst for a Fischer-Tropsch process utilizing the catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas, is selectively converted to higher hydrocarbons of relatively narrow carbon number range is disclosed. In general, the selective and notably stable catalyst, consist of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of a Fischer-Tropsch metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

Catalytic conversion of hydrocarbons to hydrogen and high-value carbon

DOEpatents

Shah, Naresh; Panjala, Devadas; Huffman, Gerald P.

2005-04-05

The present invention provides novel catalysts for accomplishing catalytic decomposition of undiluted light hydrocarbons to a hydrogen product, and methods for preparing such catalysts. In one aspect, a method is provided for preparing a catalyst by admixing an aqueous solution of an iron salt, at least one additional catalyst metal salt, and a suitable oxide substrate support, and precipitating metal oxyhydroxides onto the substrate support. An incipient wetness method, comprising addition of aqueous solutions of metal salts to a dry oxide substrate support, extruding the resulting paste to pellet form, and calcining the pellets in air is also discloses. In yet another aspect, a process is provided for producing hydrogen from an undiluted light hydrocarbon reactant, comprising contacting the hydrocarbon reactant with a catalyst as described above in a reactor, and recovering a substantially carbon monoxide-free hydrogen product stream. In still yet another aspect, a process is provided for catalytic decomposition of an undiluted light hydrocarbon reactant to obtain hydrogen and a valuable multi-walled carbon nanotube coproduct.

Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol over Nitrogen-Doped Carbon-Supported Iron Catalysts.

PubMed

Li, Jiang; Liu, Jun-Ling; Zhou, Hong-Jun; Fu, Yao

2016-06-08

Iron-based heterogeneous catalysts, which were generally prepared by pyrolysis of iron complexes on supports at elevated temperature, were found to be capable of catalyzing the transfer hydrogenation of furfural (FF) to furfuryl alcohol (FFA). The effects of metal precursor, nitrogen precursor, pyrolysis temperature, and support on catalytic performance were examined thoroughly, and a comprehensive study of the reaction parameters was also performed. The highest selectivity of FFA reached 83.0 % with a FF conversion of 91.6 % under the optimal reaction condition. Catalyst characterization suggested that iron cations coordinated by pyridinic nitrogen functionalities were responsible for the enhanced catalytic activity. The iron catalyst could be recycled without significant loss of catalytic activity for five runs, and the destruction of the nitrogen-iron species, the presence of crystallized Fe2 O3 phase, and the pore structure change were the main reasons for catalyst deactivation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Perspective on the Selective Catalytic Reduction (SCR) of NO with NH 3 by Supported V 2O 5 –WO 3/TiO 2 Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Jun-Kun; Wachs, Israel E.

We report the selective catalytic reduction (SCR) of NO x with NH 3 to harmless N 2 and H 2O plays a crucial role in reducing highly undesirable NO x acid gas emissions from large utility boilers, industrial boilers, municipal waste plants, and incinerators. The supported V 2O 5 –WO 3/TiO 2 catalysts have become the most widely used industrial catalysts for these SCR applications since introduction of this technology in the early 1970s. Lastly, this Perspective examines the current fundamental understanding and recent advances of the supported V 2O 5 –WO 3/TiO 2 catalyst system: (i) catalyst synthesis, (ii)more » molecular structures of titaniasupported vanadium and tungsten oxide species, (iii) surface acidity, (iv) catalytic active sites, (v) surface reaction intermediates, (vi) reaction mechanism, (vii) ratedetermining- step, and (viii) reaction kinetics.« less

Palladium nanoparticles dispersed on the hollow aluminosilicate microsphere@hierarchical γ-AlOOH as an excellent catalyst for the hydrogenation of nitroarenes under ambient conditions

NASA Astrophysics Data System (ADS)

Tian, Meng; Cui, Xueliang; Dong, Chunxu; Dong, Zhengping

2016-12-01

In this study, a novel catalyst has been prepared through supporting Pd nanoparticles (NPs) on the surface of boehmite (γ-AlOOH) based hollow aluminosilicate microspheres (HAM@γ-AlOOH). The prepared Pd/HAM@γ-AlOOH catalyst has high catalytic activity for the hydrogenation of nitroarenes to their corresponding amino derivatives with high yields at ambient conditions. The high catalytic efficiency is attributed to the large pore size of the flower-like hierarchical flakes structure of HAM@γ-AlOOH, that gives Pd NPs on the support surface easy accessibility. Moreover, the Pd/HAM@γ-AlOOH catalyst can also be easily recycled at least five times without obvious decrease of catalytic activity. This work may provide a useful method for the fabrication of supported noble metal NP-based catalysts on the surface of mesoporous hierarchical structure materials with easy accessibility and superior activity.

A Perspective on the Selective Catalytic Reduction (SCR) of NO with NH 3 by Supported V 2O 5 –WO 3/TiO 2 Catalysts

DOE PAGES

Lai, Jun-Kun; Wachs, Israel E.

2018-06-04

We report the selective catalytic reduction (SCR) of NO x with NH 3 to harmless N 2 and H 2O plays a crucial role in reducing highly undesirable NO x acid gas emissions from large utility boilers, industrial boilers, municipal waste plants, and incinerators. The supported V 2O 5 –WO 3/TiO 2 catalysts have become the most widely used industrial catalysts for these SCR applications since introduction of this technology in the early 1970s. Lastly, this Perspective examines the current fundamental understanding and recent advances of the supported V 2O 5 –WO 3/TiO 2 catalyst system: (i) catalyst synthesis, (ii)more » molecular structures of titaniasupported vanadium and tungsten oxide species, (iii) surface acidity, (iv) catalytic active sites, (v) surface reaction intermediates, (vi) reaction mechanism, (vii) ratedetermining- step, and (viii) reaction kinetics.« less

Observation of three-component fermions in the topological semimetal molybdenum phosphide.

PubMed

Lv, B Q; Feng, Z-L; Xu, Q-N; Gao, X; Ma, J-Z; Kong, L-Y; Richard, P; Huang, Y-B; Strocov, V N; Fang, C; Weng, H-M; Shi, Y-G; Qian, T; Ding, H

2017-06-29

In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Observation of three-component fermions in the topological semimetal molybdenum phosphide

NASA Astrophysics Data System (ADS)

Lv, B. Q.; Feng, Z.-L.; Xu, Q.-N.; Gao, X.; Ma, J.-Z.; Kong, L.-Y.; Richard, P.; Huang, Y.-B.; Strocov, V. N.; Fang, C.; Weng, H.-M.; Shi, Y.-G.; Qian, T.; Ding, H.

2017-06-01

In quantum field theory, Lorentz invariance leads to three types of fermion—Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Heterogeneous Electrocatalyst of Palladium-Cobalt-Phosphorus on Carbon Support for Oxygen Reduction Reaction in High Temperature Proton Exchange Membrane Fuel Cells.

PubMed

You, Dae Jong; Pak, Chanho; Jin, Seon-Ah; Lee, Kang Hee; Kwon, Kyungjung; Choi, Kyoung Hwan; Heo, Pil Won; Jang, Hongchul; Kim, Jun Young; Kim, Ji Man

2016-05-01

Palladium-cobalt-phosphorus (PdCoP) catalysts supported on carbon (Ketjen Black) were investigated as a cathode catalyst for oxygen reduction reaction (ORR) in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The PdCoP catalyst was synthesized via a modified polyol process in teflon-sealed reactor by microwave-heating. From X-ray diffraction and transmission electron microscopic analysis, the PdCoP catalyst exhibits a face-centered cubic structure, similar to palladium (Pd), which is attributed to form a good solid solution of Co atoms and P atoms in the Pd lattice. The PdCoP nanoparticles with average diameter of 2.3 nm were uniformly distributed on the carbon support. The electrochemical surface area (ECSA) and ORR activity of PdP, PdCo and PdCoP catalysts were measured using a rotating disk electrode technique with cyclic voltammetry and the linear sweep method. The PdCoP catalysts showed the highest performances for ECSA and ORR, which might be attributed both to formation of small nanoparticle by phosphorus atom and to change in lattice constant of Pd by cobalt atom. Furthermore, The HT-PEMFCs single cell performance employing PdCoP catalyst exhibited an enhanced cell performance compared to a single cell using the PdP and PdCo catalysts. This result indicates the importance of electric and geometric control of Pd alloy nanoparticles that can improve the catalytic activity. This synergistic combination of Co and P with Pd could provide the direction of development of non-Pt catalyst for fuel cell system.

Massachusetts Lowell low speed wind tunnel (LSWT) test section

NASA Astrophysics Data System (ADS)

Anderson, Erik William

The alumina and hybrid alumina-silica FT catalyst were prepared by one-step solgel/oil-drop methods using metal-nitrate-solutions (method-I), and nanoparticle-metaloxides (method-2). The nanoparticle-metal-oxides did not participate in solubility equilibria in contrast to metal nitrate in method-1 causing no metal ion seepage; therefore, method-2 yields higher XRF metal loading efficiency than method-1. The thermal analysis confirmed that the metal loading by method-1 and method-2 involved two different pathways. Method-1 involves solubility equilibria in the conversion of metal-nitrate to metal- hydroxide and finally to metal-oxide, while in method-2 nanoparticle-metal-oxide remained intact during sol-gel-oil-drop and calcination steps. The alumina supported catalysts were dominated by gamma-alumina PXRD peaks in alumina catalysts while amorphous alumino-silicate phase was the bulk of hybrid alumina-silica catalysts. The presence of cobalt oxides (CoO, Co3O4) and iron oxides (FeO, Fe2O3) phases are confirmed in the catalysts prepared by method-1 and method-2. The PXRD analysis indicated weak peak intensities in catalysts with 5 wt. % total metal loading. PXRD pattern confirmed alloy formation in the bimetallic catalysts (CoFe2O4) on alumina support phase gamma-A12 O3. The surface area and pore diameter of hybrid alumina-silica granules (301 - 372 m2/g and 7.3 nm) showed better values than the alumina granules (251 - 256 m2/g and 6.5 nm). The support pore diameter of both types of granules is within the mesoporous range (1 - 50 nm). The morphology of all the catalysts is preserved upon metal loading and heat treatments. The surface characteristics of the sol-gel-oil-drop method prepared catalysts indicate there was no significant pore blockage of the support below 10 wt % total metal loading. The CO conversion of the FT catalysts was measured to screen catalytic active metals and determine the optimum temperatures of the FT reaction for the alumina catalysts. The alumina FT catalysts showed an optimum reaction temperature of 250 °C. Hydrocarbon production and CO conversion of alumina and hybrid alumina-silica FT catalysts were investigated. Among monometallic alumina catalysts, Co(5%) showed a higher CO conversion. The incorporation of Fe to Co increased CO conversion and hydrocarbon production. Increased Fe content in the bimetallic catalysts prepared by combined method-1&2, decreased CO conversion and hydrocarbon production, and increased CO 2 production. The bimetallic nano-Co(2.5%)nano-Fe(2.5%) prepared by method-2 alone showed higher CO conversion comparable to the Co(4%)nano-Fe(l %). Hybrid alumina-silica FT catalysts showed a higher CO conversion than the alumina FT catalysts due to better surface characteristics. The monometallic catalysts showed higher selectivity to C1-C4 hydrocarbon than bimetallic. The bimetallic alumina FT catalysts prepared by method-2 showed slightly higher C5+ selectivity compared to the higher Co catalysts prepared by combined method- I &2. The Ru promotion showed a significant effect on the CO conversion and 11 product distribution of the monometallic catalysts. There was no significant effect on the CO conversion on the (Co-Fe) bimetallic catalysts, but hydrocarbon production slightly increased when promoted by 0.5 wt.% Ru.

Olefin polymerization from single site catalysts confined within porous media

NASA Astrophysics Data System (ADS)

Kasi, Rajeswari M.

Single Site Catalysts (SSCs) have been utilized for olefin polymerization. Altering the metal-ligand architecture in the SSCs, polyolefin properties can be enhanced in a rational manner. This influence of the ligands in the SSC on the property of polyolefins prepared can be referred to as the primary ligand influence. Extending this understanding and subsequent control of the metal-ligand framework to the interaction of SSCs within organic and inorganic supports is vital for the synthesis of polyolefins with tailored properties. The motivation behind this thesis was to explore the support influence on the reactivity of the SSC tethered to a support matrix during ethylene homo and copolymerization. In order to address this question of the support influence on the final polyolefin properties, synthetic routes to covalently bind SSCs on different matrices have been explored. Two distinct supported SSCs have been used to prepare branched polyethylenes. Branched polyethylenes can be prepared by either copolymerization (ethylene and alpha-olefin) or oligomerization/copolymerization processes (ethylene and in situ generated alpha-olefin). Synthetic routes to prepare precursor catalysts to Constrained Geometry Catalysts (CGCs) by silyl elimination chemistry have been developed (Chapter 2). Efficient synthetic protocols to assemble CGCs on aminomethylpolysytrene matrices (Chapter 3) and amine-functionalized mesoporous silica (Chapter 4) are also reported. These supported catalysts, with appropriate cocatalysts have been used to prepare ethylene homo and copolymers, the polymer thermal properties and microstructures were analyzed by various analytical techniques. Branched polyethylenes (LLDPE) can be prepared by copolymerization chemistry. It has been observed is that the influence of the support is seen in the production of lower crystalline forms of high density polyethylene (HDPE, 20--50% crystalline), while homogeneous polymerization of analogous soluble CGCs afford HDPE of higher percent crystallinity (greater than 60% crystalline). High-density polyethylene with crystallinity of 40--60% can be prepared by using cocatalysts tethered to AMPS or silica in conjunction with analogous soluble, homogeneous CGCs (Chapter 6). Preparative methods to assemble piano stool complexes on hydroxy polystyrenes have been designed. These supported catalysts in conjunction with cocatalysts act as both oligomerization and copolymerization catalysts and allow the preparation of branched polyethylenes from ethylene only feed (Chapter 7).

Calcium oxide supported gold nanoparticles as catalysts for the selective epoxidation of styrene by t-butyl hydroperoxide.

PubMed

Dumbre, Deepa K; Choudhary, Vasant R; Patil, Nilesh S; Uphade, Balu S; Bhargava, Suresh K

2014-02-01

Gold nanoparticles are deposited on basic CaO supports as catalysts for the selective conversion of styrene into styrene oxide. Synthetic methods, gold loading and calcination temperatures are varied to permit an understanding of their influence on gold nanoparticle size, the presence of cationic gold species and the nature of interaction between the gold nanoparticles and the CaO support. Based on these studies, optimal conditions are designed to make the Au/CaO catalyst efficient for the selective epoxidation of styrene. Copyright © 2013 Elsevier Inc. All rights reserved.

Preparation, characterization, and activity of α-Ti(HPO4)2 supported metallocene catalysts

NASA Astrophysics Data System (ADS)

Shi, Yasai; Yuan, Yuan; Xu, Qinghong; Yi, Jianjun

2016-10-01

A series of heterogeneous catalysts by loading metallocenes on surface of α-Ti(HPO4)2, a kind of solid acid, has been synthesized. Polymerization of alkenes, including ethylene and propylene, based on participation of the heterogeneous catalysts were studied and the results were compared to metallocenes supported on silica gel, α-Zr(HPO4)2 and clay. Higher catalytic activity, larger polymer molecular weight and narrow distribution of polymer molecular weight were obtained. Acidic strength of the support and its influence to metallocenes were studied to discover intrinsic factors in the polymerizations.

Enhanced conversion of syngas to liquid motor fuels

DOEpatents

Coughlin, Peter K.; Rabo, Jule A.

1986-01-01

Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

Nitrogen-based catalysts for the electrochemical reduction of CO2 to CO.

PubMed

Tornow, Claire E; Thorson, Michael R; Ma, Sichao; Gewirth, Andrew A; Kenis, Paul J A

2012-12-05

The synthesis and application of carbon-supported, nitrogen-based organometallic silver catalysts for the reduction of CO(2) is studied using an electrochemical flow reactor. Their performance toward the selective formation of CO is similar to the performance achieved when using Ag as the catalyst, but comparatively at much lower silver loading. Faradaic efficiencies of the organometallic catalyst are higher than 90%, which are comparable to those of Ag. Furthermore, with the addition of an amine ligand to Ag/C, the partial current density for CO increases significantly, suggesting a possible co-catalyst mechanism. Additional improvements in activity and selectivity may be achieved as greater insight is obtained on the mechanism of CO(2) reduction and on how these complexes assemble on the carbon support.

V-doped TiO2 supported Pt as a promising oxygen reduction reaction catalyst: Synthesis, characterization and in-situ evaluation in proton exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Bharti, Abha; Cheruvally, Gouri

2017-09-01

This study deals with the synthesis and characterization of V-doped, TiO2 supported Pt catalyst (Pt/V-TiO2) for oxygen reduction reaction (ORR) and its in-situ performance investigation in proton exchange membrane (PEM) fuel cell. Pt/V-TiO2 nanocomposite catalyst is prepared via a facile sol-gel and microwave assisted, modified chemical reduction route and its performance is compared with the undoped TiO2 supported catalyst, Pt/TiO2 prepared in an identical way. The prepared Pt/V-TiO2 and Pt/TiO2 catalysts are employed as cathode catalyst in PEM fuel cell and compared with standard Pt/C catalyst. Their comparative studies are conducted with physical and electrochemical techniques. In-situ electrochemical characterization studies show improved ORR catalytic activity of Pt/V-TiO2 compared to Pt/TiO2. Furthermore, both Pt/TiO2 and Pt/V-TiO2 are more stable than Pt/C when subjected to 6000 voltammetric cycles in the range of 0.2-1.2 V vs. standard hydrogen electrode in operating fuel cell conditions, losing only <20% of its electrochemical surface area as compared to 50% loss exhibited by Pt/C. This study thus demonstrates Pt/V-TiO2 nanocomposite material as a potential cathode catalyst for PEM fuel cell with immense scope for further investigation.

Enhancing low-temperature activity and durability of Pd-based diesel oxidation catalysts using ZrO 2 supports

DOE PAGES

Kim, Mi -Young; Kyriakidou, Eleni A.; Choi, Jae -Soon; ...

2016-01-18

In this study, we investigated the impact of ZrO 2 on the performance of palladium-based oxidation catalysts with respect to low-temperature activity, hydrothermal stability, and sulfur tolerance. Pd supported on ZrO 2 and SiO 2 were synthesized for a comparative study. Additionally, in an attempt to maximize the ZrO 2 surface area and improve sulfur tolerance, a Pd support with ZrO 2-dispersed onto SiO 2 was studied. The physicochemical properties of the catalysts were examined using ICP, N 2 sorption, XRD, SEM, TEM, and NH 3-, CO 2-, and NO x-TPD. The activity of the Pd catalysts were measured frommore » 60 to 600 °C in a flow of 4000 ppm CO, 500 ppm NO, 1000 ppm C 3H 6, 4% O 2, 5% H 2O, and Ar balance. The Pd catalysts were evaluated in fresh, sulfated, and hydrothermally aged states. Overall, the ZrO 2-containing catalysts showed considerably higher CO and C 3H 6 oxidation activity than Pd/SiO 2 under the reaction conditions studied.« less

High aspect ratio catalytic reactor and catalyst inserts therefor

DOEpatents

Lin, Jiefeng; Kelly, Sean M.

2018-04-10

The present invention relates to high efficient tubular catalytic steam reforming reactor configured from about 0.2 inch to about 2 inch inside diameter high temperature metal alloy tube or pipe and loaded with a plurality of rolled catalyst inserts comprising metallic monoliths. The catalyst insert substrate is formed from a single metal foil without a central supporting structure in the form of a spiral monolith. The single metal foil is treated to have 3-dimensional surface features that provide mechanical support and establish open gas channels between each of the rolled layers. This unique geometry accelerates gas mixing and heat transfer and provides a high catalytic active surface area. The small diameter, high aspect ratio tubular catalytic steam reforming reactors loaded with rolled catalyst inserts can be arranged in a multi-pass non-vertical parallel configuration thermally coupled with a heat source to carry out steam reforming of hydrocarbon-containing feeds. The rolled catalyst inserts are self-supported on the reactor wall and enable efficient heat transfer from the reactor wall to the reactor interior, and lower pressure drop than known particulate catalysts. The heat source can be oxygen transport membrane reactors.

Sintering-resistant Single-Site Nickel Catalyst Supported by Metal-Organic Framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhanyong; Schweitzer, Neil; League, Aaron

2016-02-17

Developing supported single-site catalysts is an important goal in heterogeneous catalysis, since the well-defined active sites afford opportunities for detailed mechanistic studies, thereby facilitating the design of improved catalysts. We present herein a method for installing Ni ions uniformly and precisely on the node of a Zr-based MOF, NU-1000, in high density and large quantity (denoted as Ni-AIM) using atomic layer deposition (ALD) in a metal–organic framework (MOF) (AIM). Ni-AIM is demonstrated to be an efficient gas-phase hydrogenation catalyst upon activation. The structure of the active sites in Ni-AIM is proposed, revealing its single-site nature. More importantly, due to themore » organic linker used to construct the MOF support, the Ni ions stay isolated throughout the hydrogenation catalysis, in accord with its long-term stability. A quantum chemical characterization of the catalyst and the catalytic process complements the experimental results. With validation of computational modeling protocols, we further targeted ethylene oligomerization catalysis by Ni-AIM guided by theoretical prediction. Given the generality of the AIM methodology, this emerging class of materials should prove ripe for the discovery of new catalysts for the transformation of volatile substrates.« less

Oxidative coupling of methane over a Sr-promoted La{sub 2}O{sub 3} catalyst supported on a low surface area porous catalyst carrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, V.R.; Uphade, B.S.; Mulla, S.A.R.

1997-09-01

Oxidative coupling of methane (OCM) to higher hydrocarbons over Sr-promoted La{sub 2}O{sub 3} supported on commercial low surface area porous catalyst carriers at 800 and 850 C and a space velocity of 102,000 cm{sup 3}/g{center_dot}h has been thoroughly investigated. Effects of support, catalyst particle size, linear gas velocity, Sr/La ratio, CH{sub 4}/O{sub 2} ratio in the feed, and catalyst dilution by inert solid particles on the conversion, yield, or selectivity and product ratios (C{sub 2}H{sub 4}/C{sub 2}H{sub 6} and CO/CO{sub 2}) in the OCM process have been studied. The catalysts have been characterized for their basicity, acidity, and oxygen chemisorptionmore » by the TPD of CO{sub 2}, ammonia, and oxygen, respectively, from 50 to 950 C and also characterized for their surface area. The supported catalysts showed better performance than the unsupported one. The best OCM results (obtained over Sr-La{sub 2}O{sub 3}/SA-5205 with a Sr/La ratio of 0.3 at a space velocity of 102,000 cm{sup 3}/g{center_dot}h) are 30.1% CH{sub 4} conversion with 65.6% selectivity for C{sub 2+} (or 19.7% C{sub 2+}-yield) at 850 C (CH{sub 4}/O{sub 2} = 16.0). The basicity is strongly influenced by the Sr/La ratio; the supported catalysts showed the best performance for their Sr/La ratio of about 0.3. The methane/O{sub 2} ratio also showed a strong influence for their Sr/La ratio of about 0.3. The methane/O{sub 2} ratio also showed a strong influence on the OCM process. However, the influence of linear gas velocity and particle size is found to be small; it results mainly from the temperature gradient in the catalyst. The catalyst dilution has beneficial effects for achieving a higher C{sub 2}H{sub 4}/C{sub 2}H{sub 6} ratio and also for reducing the hazardous nature of the OCM process because of the coupling of the exothermic oxidative conversion reactions and the endothermic thermal cracking reactions and also due to the increased heat transfer area.« less

Effect of SiO 2-ZrO 2 supports prepared by a grafting method on hydrogen production by steam reforming of liquefied natural gas over Ni/SiO 2-ZrO 2 catalysts

NASA Astrophysics Data System (ADS)

Seo, Jeong Gil; Youn, Min Hye; Song, In Kyu

SiO 2-ZrO 2 supports with various zirconium contents are prepared by grafting a zirconium precursor onto the surface of commercial Carbosil silica. Ni(20 wt.%)/SiO 2-ZrO 2 catalysts are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of SiO 2-ZrO 2 supports on the performance of the Ni(20 wt.%)/SiO 2-ZrO 2 catalysts is investigated. SiO 2-ZrO 2 prepared by a grafting method serves as an efficient support for the nickel catalyst in the steam reforming of LNG. Zirconia enhances the resistance of silica to steam significantly and increases the interaction between nickel and the support, and furthermore, prevents the growth of nickel oxide species during the calcination process through the formation of a ZrO 2-SiO 2 composite structure. The crystalline structures and catalytic activities of the Ni(20 wt.%)/SiO 2-ZrO 2 catalysts are strongly influenced by the amount of zirconium grafted. The conversion of LNG and the yield of hydrogen show volcano-shaped curves with respect to zirconium content. Among the catalysts tested, the Ni(20 wt.%)/SiO 2-ZrO 2 (Zr/Si = 0.54) sample shows the best catalytic performance in terms of both LNG conversion and hydrogen yield. The well-developed and pure tetragonal phase of ZrO 2-SiO 2 (Zr/Si = 0.54) appears to play an important role in the adsorption of steam and subsequent spillover of steam from the support to the active nickel. The small particle size of the metallic nickel in the Ni(20 wt.%)/SiO 2-ZrO 2 (Zr/Si = 0.54) catalyst is also responsible for its high performance.

Catalytic method for synthesizing hydrocarbons

DOEpatents

Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

Catalytic method for synthesizing hydrocarbons

DOEpatents

Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

1984-01-01

A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

Subnanometer to nanometer transition metal CO oxidation catalysts

DOEpatents

Vajda, Stefan; Fortunelli, Alessandro; Yasumatsu, Hisato

2017-12-26

The present invention provides a catalyst defined in part by a conductive substrate; a film overlaying a surface of the substrate; and a plurality of metal clusters supported by the layer, wherein each cluster comprises between 8 and 11 atoms. Further provided is a catalyst defined in part by a conductive substrate; a layer overlaying a surface of the substrate; and a plurality of metal clusters supported by the layer, wherein each cluster comprises at least two metals.

Identifying the role of N-heteroatom location in the activity of metal catalysts for alcohol oxidation

DOE PAGES

Chan-Thaw, Carine E.; Veith, Gabriel M.; Villa, Alberto; ...

2015-04-02

Here, this work focuses on understanding how the bonding of nitrogen heteroatoms contained on/in a activated carbon support influence the stability and reactivity of a supported Pd catalyst for the oxidation of alcohols in solution. The results show that simply adding N groups via solution chemistry is insufficient to improve catalytic properties. Instead a strongly bound N moiety is required to activate the catalyst and stabilize the metal particles.

Development of Molecular Catalysts to Bridge the Gap between Heterogeneous and Homogeneous Catalysts

NASA Astrophysics Data System (ADS)

Ye, Rong

Catalysts, heterogeneous, homogeneous, and enzymatic, are comprised of nanometer-sized inorganic and/or organic components. They share molecular factors including charge, coordination, interatomic distance, bonding, and orientation of catalytically active atoms. By controlling the governing catalytic components and molecular factors, catalytic processes of a multichannel and multiproduct nature could be run in all three catalytic platforms to create unique end-products. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis. Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles - some without homogeneous analogues - for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimize and expand the scope of their reactivity and selectivity. Ongoing efforts are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence and structural uniformity, dendrimers have proven to be versatile scaffolds for the synthesis and stabilization of small nanoclusters. Then these dendrimer-encapsulated metal clusters (DEMCs) are adsorbed onto mesoporous silica. Through this method, we have achieved selective transformations that had been challenging to accomplish in a heterogeneous setting, e.g. pi-bond activation and aldol reactions. Extensive investigation into the catalytic systems under reaction conditions allowed us to correlate the structural features (e.g. oxidation states) of the catalysts and their activity. Moreover, we have demonstrated that supported DEMCs are also excellent catalysts for typical heterogeneous reactions, including hydrogenation and alkane isomerization. Critically, these investigations also confirmed that the supported DEMCs are heterogeneous and stable against leaching. Catalysts optimization is achieved through the modulation of various parameters. The clusters are oxidized (e.g., with PhICl2) or reduced (e.g., with H2) in situ. Changing the dendrimer properties (e.g., generation, terminal functional groups) is analogous to ligand modification in homogeneous catalysts, which affect both catalytic activity and selectivity. Similarly, pore size of the support is another factor in determining product distribution. In a flow reactor, the flow rate is adjusted to control the residence time of the starting material and intermediates, and thus the final product selectivity. Our approach to heterogeneous catalysis affords various advantages: (1) the catalyst system can tap into the reactivity typical to homogeneous catalysts, which conventional heterogeneous catalysts could not achieve; (2) unlike most homogeneous catalysts with comparable performance, the heterogenized homogeneous catalysts can be recycled; (3) improved activity or selectivity compared to conventional homogeneous catalysts is possible because of uniquely heterogeneous parameters for optimization. While localized surface plasmon resonance (LSPR) provides a powerful platform for nanoparticle catalysis, our studies suggest that in some cases interband transitions should be considered as an alternative mechanism of light-driven nanoparticle catalysis. The benefits already demonstrated by plasmonic nanostructures as catalysts provided the impetus for examining complementary activation modes based on the metal nanoparticle itself. Leveraging these transitions has the potential to provide a means to highly active catalysis modes that would otherwise be challenging to access. For example, for the preparation of highly active metal catalysts on a subnanosized scale is challenging, thus limiting their exploitation and study in catalysis. Our work suggests a novel and facile strategy for the formation of highly active gold nanocluster catalysts by light illumination of the interband transitions in the presence of the appropriate substrate.

Crumpled rGO-supported Pt-Ir bifunctional catalyst prepared by spray pyrolysis for unitized regenerative fuel cells

NASA Astrophysics Data System (ADS)

Kim, In Gyeom; Nah, In Wook; Oh, In-Hwan; Park, Sehkyu

2017-10-01

Three-dimensional (3D) crumpled reduced graphene oxide supported Pt-Ir alloys that served as bifunctional oxygen catalysts for use in untized regenerative fuel cells were synthesized by a facile spray pyrolysis method. Pt-Ir catalysts supported on rGO (Pt-Ir/rGOs) were physically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) to observe change in composition by heat treatment, alloying, and morphological transition of the catalysts. Their catalytic activities and stabilities for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) conditions were electrochemically investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), potential cycling and hold tests on the rotating disk electrode (RDE). Pt-Ir/rGO with no post heat-treatment (Pt-Ir/rGO_NP) showed a lower activity for ORR and OER although metal nanoparticles decorated on the support are relatively small. However, Pt-Ir/rGO showed remarkably enhanced activity following heat treatment, depending on temperature. Pt-Ir/rGO heat-treated at 600 °C after spray pyrolysis (Pt-Ir/rGO_P600) exhibited a higher activity and stability than a commercially available Pt/C catalyst kept under the ORR condition, and it also revealed a comparable OER activity and durability versus the commercial unsupported Ir catalyst.

Reverse Micelle Synthesis and Characterization of Supported Pt/Ni Bimetallic Catalysts on gamma-Al2O3

DOE Office of Scientific and Technical Information (OSTI.GOV)

B Cheney; J Lauterbach; J Chen

2011-12-31

Reverse micelle synthesis was used to improve the nanoparticle size uniformity of bimetallic Pt/Ni nanoparticles supported on {gamma}-Al{sub 2}O{sub 3}. Two impregnation methods were investigated to optimize the use of the micelle method: (1) step-impregnation, where Ni nanoparticles were chemically reduced in microemulsion and then supported, followed by Pt deposition using incipient wetness impregnation, and (2) co-impregnation, where Ni and Pt were chemically reduced simultaneously in microemulsion and then supported. Transmission electron microscopy (TEM) was used to characterize the particle size distribution. Atomic absorption spectroscopy (AAS) was used to perform elemental analysis of bimetallic catalysts. Extended X-ray absorption fine structuremore » (EXAFS) measurements were utilized to confirm the formation of the Pt-Ni bimetallic bond in the step-impregnated catalyst. CO pulse chemisorption and Fourier transform infrared spectroscopy (FTIR) studies of 1,3-butadiene hydrogenation in a batch reactor were performed to determine the catalytic activity. Step-impregnated Pt/Ni catalyst demonstrated enhanced hydrogenation activity over the parent monometallic Pt and Ni catalysts due to bimetallic bond formation. The catalyst synthesized using co-impregnation showed no enhanced activity, behaving similarly to monometallic Ni. Overall, our results indicate that reverse micelle synthesis combined with incipient wetness impregnation produced small, uniform nanoparticles with bimetallic bonds that enhanced hydrogenation activity.« less

Non-carbon titanium cobalt nitride nanotubes supported platinum catalyst with high activity and durability for methanol oxidation reaction

NASA Astrophysics Data System (ADS)

Chen, Xiaoxiang; Li, Wuyi; Pan, Zhanchang; Xu, Yanbin; Liu, Gen; Hu, Guanghui; Wu, Shoukun; Li, Jinghong; Chen, Chun; Lin, Yingsheng

2018-05-01

Titanium cobalt nitride nanotubes (Ti0.95Co0.05N NTs) hybrid support, a novel robust non-carbon support material prepared by solvothermal and post-nitriding processes, is further decorated with Pt nanoparticles for the electrooxidation of methanol. The catalyst is characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The morphology, structure and composition of the synthesized Ti0.95Co0.05N NTs suggest that the nanotube wall is porous and consists of homogeneous cohesively attached nitrides nanocube particles. Notable, Ti0.95Co0.05N NTs supported Pt catalyst exhibits significantly improved catalytic activity and durability for methanol electrooxidation compared with the conventional JM Pt/C catalyst. The experimental data indicate that enhanced catalytic activity and stability of Pt/Ti0.95Co0.05N NTs towards methanol electrooxidation might be mainly attributed to the tubular nanostructures and synergistic effect introduced by the Co doping. Both of them are playing an important role in improving the activity and durability of the Ti0.95Co0.05N NTs catalyst.

Interfaces in Heterogeneous Catalysts: Advancing Mechanistic Understanding through Atomic-Scale Measurements.

PubMed

Gao, Wenpei; Hood, Zachary D; Chi, Miaofang

2017-04-18

Developing novel catalysts with high efficiency and selectivity is critical for enabling future clean energy conversion technologies. Interfaces in catalyst systems have long been considered the most critical factor in controlling catalytic reaction mechanisms. Interfaces include not only the catalyst surface but also interfaces within catalyst particles and those formed by constructing heterogeneous catalysts. The atomic and electronic structures of catalytic surfaces govern the kinetics of binding and release of reactant molecules from surface atoms. Interfaces within catalysts are introduced to enhance the intrinsic activity and stability of the catalyst by tuning the surface atomic and chemical structures. Examples include interfaces between the core and shell, twin or domain boundaries, or phase boundaries within single catalyst particles. In supported catalyst nanoparticles (NPs), the interface between the metallic NP and support serves as a critical tuning factor for enhancing catalytic activity. Surface electronic structure can be indirectly tuned and catalytically active sites can be increased through the use of supporting oxides. Tuning interfaces in catalyst systems has been identified as an important strategy in the design of novel catalysts. However, the governing principle of how interfaces contribute to catalyst behavior, especially in terms of interactions with intermediates and their stability during electrochemical operation, are largely unknown. This is mainly due to the evolving nature of such interfaces. Small changes in the structural and chemical configuration of these interfaces may result in altering the catalytic performance. These interfacial arrangements evolve continuously during synthesis, processing, use, and even static operation. A technique that can probe the local atomic and electronic interfacial structures with high precision while monitoring the dynamic interfacial behavior in situ is essential for elucidating the role of interfaces and providing deeper insight for fine-tuning and optimizing catalyst properties. Scanning transmission electron microscopy (STEM) has long been a primary characterization technique used for studying nanomaterials because of its exceptional imaging resolution and simultaneous chemical analysis. Over the past decade, advances in STEM, that is, the commercialization of both aberration correctors and monochromators, have significantly improved the spatial and energy resolution. Imaging atomic structures with subangstrom resolution and identifying chemical species with single-atom sensitivity are now routine for STEM. These advancements have greatly benefitted catalytic research. For example, the roles of lattice strain and surface elemental distribution and their effect on catalytic stability and reactivity have been well documented in bimetallic catalysts. In addition, three-dimensional atomic structures revealed by STEM tomography have been integrated in theoretical modeling for predictive catalyst NP design. Recent developments in stable electronic and mechanical devices have opened opportunities to monitor the evolution of catalysts in operando under synthesis and reaction conditions; high-speed direct electron detectors have achieved sub-millisecond time resolutions and allow for rapid structural and chemical changes to be captured. Investigations of catalysts using these latest microscopy techniques have provided new insights into atomic-level catalytic mechanisms. Further integration of new microscopy methods is expected to provide multidimensional descriptions of interfaces under relevant synthesis and reaction conditions. In this Account, we discuss recent insights on understanding catalyst activity, selectivity, and stability using advanced STEM techniques, with an emphasis on how critical interfaces dictate the performance of precious metal-based heterogeneous catalysts. The role of extended interfacial structures, including those between core and shell, between separate phases and twinned grains, between the catalyst surface and gas, and between metal and support are discussed. We also provide an outlook on how emerging electron microscopy techniques, such as vibrational spectroscopy and electron ptychography, will impact future catalysis research.

Catalysts for conversion of syngas to liquid motor fuels

DOEpatents

Rabo, Jule A.; Coughlin, Peter K.

1987-01-01

Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst composition capable of ensuring the production of only relatively minor amounts of heavy products boiling beyond the diesel oil range. The catalyst composition, having desirable stability during continuous production operation, employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component. The latter component is a steam-stabilized zeolite Y catalyst of hydrophobic character, desirably in acid-extracted form.

COMPARISON OF HOPCALITE AND A SUPPORTED HOPCALITE FOR APPLICABILITY TO SUBMARINE USE.

DTIC Science & Technology

have been investigated with regard to suitable physical properties and catalytic activity. In this report the presently used Hopcalite catalyst is...compared with a supported Hopcalite catalyst with an alumina base. It was found that the present Hopcalite was clearly superior in almost all aspects of catalytic activity to the supported Hopcalite . (Author)

Effect of nanostructured carbon support on copper electrocatalytic activity toward CO 2 electroreduction to hydrocarbon fuels

DOE PAGES

Baturina, Olga; Lu, Qin; Xu, Feng; ...

2016-11-10

The effect of support on electrocatalytic activity of Cu nanoparticles (NPs) towards CO 2 electroreduction to hydrocarbon fuels (CH 4 and C 2H 4) is investigated for three types of nanostructured carbons: single wall carbon nanotubes (SWNT), graphene (GP) and onion-like carbon (OLC). Cu/SWNT, Cu/GP and Cu/OLC composite catalysts are synthesized and characterized by X-Ray diffraction analysis, transmission electron microscopy and electrochemical surface area measurements. Electrocatalytic activities of the synthesized materials, as measured in an electrochemical cell connected to a gas chromatograph, are compared to that of Cu NPs supported on Vulcan carbon. All four catalysts demonstrate higher activity towardsmore » C 2H 4 generation vs CH 4, with production of the latter mostly suppressed on Cu NPs supported on nanostructured substrates. Onset potentials for C 2H 4 vs CH 4 generation are shifted positively by 200 mV for Cu/SWNT, Cu/GP, and Cu/OLC catalysts. The Cu/OLC catalyst is found to be superior to the other two nanostructured catalysts in terms of stability, activity and selectivity towards C 2H 4 generation. Its faradaic efficiency reached 60% at -1.8 V vs Ag/AgCl. The enhanced activity and stability of Cu/OLC catalyst can be attributed to the unique catalyst design, wherein a shell of OLC surrounds the Cu NPs such that the outer layer acts as a filter that protects the Cu surface from adsorption of undesirable species, enhances its electrocatalytic performance, and improves its viability in CO 2 electroreduction reaction.« less

Effect of nanostructured carbon support on copper electrocatalytic activity toward CO 2 electroreduction to hydrocarbon fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baturina, Olga; Lu, Qin; Xu, Feng

The effect of support on electrocatalytic activity of Cu nanoparticles (NPs) towards CO 2 electroreduction to hydrocarbon fuels (CH 4 and C 2H 4) is investigated for three types of nanostructured carbons: single wall carbon nanotubes (SWNT), graphene (GP) and onion-like carbon (OLC). Cu/SWNT, Cu/GP and Cu/OLC composite catalysts are synthesized and characterized by X-Ray diffraction analysis, transmission electron microscopy and electrochemical surface area measurements. Electrocatalytic activities of the synthesized materials, as measured in an electrochemical cell connected to a gas chromatograph, are compared to that of Cu NPs supported on Vulcan carbon. All four catalysts demonstrate higher activity towardsmore » C 2H 4 generation vs CH 4, with production of the latter mostly suppressed on Cu NPs supported on nanostructured substrates. Onset potentials for C 2H 4 vs CH 4 generation are shifted positively by 200 mV for Cu/SWNT, Cu/GP, and Cu/OLC catalysts. The Cu/OLC catalyst is found to be superior to the other two nanostructured catalysts in terms of stability, activity and selectivity towards C 2H 4 generation. Its faradaic efficiency reached 60% at -1.8 V vs Ag/AgCl. The enhanced activity and stability of Cu/OLC catalyst can be attributed to the unique catalyst design, wherein a shell of OLC surrounds the Cu NPs such that the outer layer acts as a filter that protects the Cu surface from adsorption of undesirable species, enhances its electrocatalytic performance, and improves its viability in CO 2 electroreduction reaction.« less

Hydrodeoxygenation and coupling of aqueous phenolics over bifunctional zeolite-supported metal catalysts.

PubMed

Hong, Do-Young; Miller, Stephen J; Agrawal, Pradeep K; Jones, Christopher W

2010-02-21

Pt supported on HY zeolite is successfully used as a bifunctional catalyst for phenol hydrodeoxygenation in a fixed-bed configuration at elevated hydrogen pressures, leading to hydrogenation-hydrogenolysis ring-coupling reactions producing hydrocarbons, some with enhanced molecular weight.

Catalysts and process for hydrogenolysis of sugar alcohols to polyols

DOEpatents

Chopade, Shubham P [East Lansing, MI; Miller, Dennis J [Okemos, MI; Jackson, James E [Haslett, MI; Werpy, Todd A [West Richland, WA; Frye, Jr., John G [Richland, WA; Zacher, Alan H [Richland, WA

2001-09-18

The present invention provides a process for preparation of low molecular weight polyols from high molecular weight polyols in a hydrogenolysis reaction under elevated temperature and hydrogen pressure. The process comprises providing in a reaction mixture the polyols, a base, and a metal catalyst prepared by depositing a transition metal salt on an inert support, reducing the metal salt to the metal with hydrogen, and passivating the metal with oxygen, and wherein the catalyst is reduced with hydrogen prior to the reaction. In particular, the process provides for the preparation of glycerol, propylene glycol, and ethylene glycol from sugar alcohols such as sorbitol or xylitol. In a preferred process, the metal catalyst comprises ruthenium which is deposited on an alumina, titania, or carbon support, and the dispersion of the ruthenium on the support increases during the hydrogenolysis reaction.

Investigation of NO(x) Removal from Small Engine Exhaust

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, Jale F.

1999-01-01

Contribution of emissions from small engines to the air pollution is significant. Due to differences in operating conditions and economics, the pollution control systems designed for automobiles will be neither suitable nor economically feasible for use on small engines. The objective of this project was to find a catalyst for the removal of NOx from the exhaust of small engines which use a rich air to fuel ratio. The desired catalyst should be inexpensive so that the cost of the pollution control unit will be only a small fraction of the total equipment cost. The high cost of noble metals makes them too expensive for use as NOx catalyst for small engines. Catalytic reduction of NO can also be accomplished by base-metal oxide catalysts. The main disadvantage of base-metal catalysts is their deactivation by poisons and high temperatures. Requirements for the length of the life of the small engine exhaust catalysts are much less than those for automobile exhaust catalysts. Since there is no oxygen in the exhaust gases, reduction selectivity is not a problem. Also, the reducing exhaust gases might help prevent the harmful interactions of the catalyst with the support. For these reasons only the supported metal oxide catalysts were investigated in this project.

Investigation of NOx Removal from Small Engine Exhaust

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, Jale F.

1999-01-01

Contribution of emissions from small engines to the air pollution is significant. Due to differences in operating conditions and economics, the pollution control systems designed for automobiles will be neither suitable nor economically feasible for use on small engines. The objective of this project was to find a catalyst for the removal of NOx from the exhaust of small engines which use a rich air to fuel ratio. The desired catalyst should be inexpensive so that the cost of the pollution control unit will be only a small fraction of the total equipment cost. The high cost of noble metals makes them too expensive for use as NOx catalyst for small engines. Catalytic reduction of Nitrogen Oxide (NO) can also be accomplished by base-metal oxide catalysts. The main disadvantage of base-metal catalysts is their deactivation by poisons and high temperatures. Requirements for the length of the life of the small engine exhaust catalysts are much less than those for automobile exhaust catalysts. Since there is no oxygen in the exhaust gases, reduction selectivity is not a problem. Also, the reducing exhaust gases might help prevent the harmful interactions of the catalyst with the support. For these reasons only the supported metal oxide catalysts were investigated in this project.

Supported metal catalysts for alcohol/sugar alcohol steam reforming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, Stephen; Zhang, He; Sun, Junming

Despite extensive studies on hydrogen production via steam reforming of alcohols and sugar alcohols, catalysts typically suffer a variety of issues from poor hydrogen selectivity to rapid deactivation. Here, we summarize recent advances in fundamental understanding of functionality and structure of catalysts for alcohol/sugar alcohol steam reforming, and provide perspectives on further development required to design highly efficient steam reforming catalysts.

Poisoning of a Silica-Supported Cobalt Catalyst due to Presence of Sulfur Impurities in Syngas during Fischer–Tropsch Synthesis: Effects of Chelating Agent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bambal, Ashish S.; Guggilla, Vidya S.; Kugler, Edwin L.

2014-04-09

The effects of sulfur impurities on the performance of cobalt-based Fischer–Tropsch catalysts are evaluated under industrially relevant operating conditions of temperature, pressure, and impurity levels. Chelating agents (CAs) were used to modify the SiO 2 support, and the performances of the CA-modified catalysts are compared with conventional Co/SiO 2 catalysts. For both the Co/SiO 2 and CA-modified catalysts, the presence of sulfur in the inlet syngas results in a notable drop in the CO conversion, an undesired shift in the hydrocarbon selectivity toward short-chain hydrocarbons, more olefins in the products, and lower product yields. In the post-poisoning stage, i.e., aftermore » termination of sulfur introduction in the inlet syngas, the CA-modified catalysts recover activity and selectivity (to some extent at least), whereas such trends are not observed for the base-case, i.e., unmodified Co/SiO 2 catalyst. Finally, the improved performance of the CA-modified catalysts in the presence of sulfur is attributed to higher densities of active sites.« less

Life Support Catalyst Regeneration Using Ionic Liquids and In Situ Resources

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Karr, Laurel J.; Paley, Mark S.; Donovan, David N.; Kramer, Teersa J.

2016-01-01

Oxygen recovery from metabolic carbon dioxide is an enabling capability for long-duration manned space flight. Complete recovery of oxygen (100%) involves the production of solid carbon. Catalytic approaches for this purpose, such as Bosch technology, have been limited in trade analyses due in part to the mass penalty for high catalyst resupply caused by carbon fouling of the iron or nickel catalyst. In an effort to mitigate this challenge, several technology approaches have been proposed. These approaches have included methods to prolong the life of the catalysts by increasing the total carbon mass loading per mass catalyst, methods for simplified catalyst introduction and removal to limit the resupply container mass, methods of using in situ resources, and methods to regenerate catalyst material. Research and development into these methods is ongoing, but only use of in situ resources and/or complete regeneration of catalyst material has the potential to entirely eliminate the need for resupply. The use of ionic liquids provides an opportunity to combine these methods in a technology approach designed to eliminate the need for resupply of oxygen recovery catalyst. Here we describe the results of an initial feasibility study using ionic liquids and in situ resources for life support catalyst regeneration, we discuss the key challenges with the approach, and we propose future efforts to advance the technology.

Molecular and Silica-Supported Molybdenum Alkyne Metathesis Catalysts: Influence of Electronics and Dynamics on Activity Revealed by Kinetics, Solid-State NMR, and Chemical Shift Analysis.

PubMed

Estes, Deven P; Gordon, Christopher P; Fedorov, Alexey; Liao, Wei-Chih; Ehrhorn, Henrike; Bittner, Celine; Zier, Manuel Luca; Bockfeld, Dirk; Chan, Ka Wing; Eisenstein, Odile; Raynaud, Christophe; Tamm, Matthias; Copéret, Christophe

2017-12-06

Molybdenum-based molecular alkylidyne complexes of the type [MesC≡Mo{OC(CH 3 ) 3-x (CF 3 ) x } 3 ] (MoF 0 , x = 0; MoF 3 , x = 1; MoF 6 , x = 2; MoF 9 , x = 3; Mes = 2,4,6-trimethylphenyl) and their silica-supported analogues are prepared and characterized at the molecular level, in particular by solid-state NMR, and their alkyne metathesis catalytic activity is evaluated. The 13 C NMR chemical shift of the alkylidyne carbon increases with increasing number of fluorine atoms on the alkoxide ligands for both molecular and supported catalysts but with more shielded values for the supported complexes. The activity of these catalysts increases in the order MoF 0 < MoF 3 < MoF 6 before sharply decreasing for MoF 9 , with a similar effect for the supported systems (MoF 0 ≈ MoF 9 < MoF 6 < MoF 3 ). This is consistent with the different kinetic behavior (zeroth order in alkyne for MoF 9 derivatives instead of first order for the others) and the isolation of stable metallacyclobutadiene intermediates of MoF 9 for both molecular and supported species. Detailed solid-state NMR analysis of molecular and silica-supported metal alkylidyne catalysts coupled with DFT/ZORA calculations rationalize the NMR spectroscopic signatures and discernible activity trends at the frontier orbital level: (1) increasing the number of fluorine atoms lowers the energy of the π*(M≡C) orbital, explaining the more deshielded chemical shift values; it also leads to an increased electrophilicity and higher reactivity for catalysts up to MoF 6 , prior to a sharp decrease in reactivity for MoF 9 due to the formation of stable metallacyclobutadiene intermediates; (2) the silica-supported catalysts are less active than their molecular analogues because they are less electrophilic and dynamic, as revealed by their 13 C NMR chemical shift tensors.

Advanced Coal Liquefaction Research and Development Facility, Wilsonville, Alabama. Run 262 with Black Thunder subbituminous coal: Technical progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This report presents the results of Run 262 performed at the Advanced Coal Liquefaction R&D Facility in Wilsonville, Alabama. The run started on July 10, 1991 and continued until September 30, 1991, operating in the Close-Coupled Integrated Two-Stage Liquefaction mode processing Black Thunder Mine subbituminous coal (Wyodak-Anderson seam from Wyoming Powder River Basin). A dispersed molybdenum catalyst was evaluated for its performance. The effect of the dispersed catalyst on eliminating solids buildup was also evaluated. Half volume reactors were used with supported Criterion 324 1/16`` catalyst in the second stage at a catalyst replacement rate of 3 lb/ton of MFmore » coal. The hybrid dispersed plus supported catalyst system was tested for the effect of space velocity, second stage temperature, and molybdenum concentration. The supported catalyst was removed from the second stage for one test period to see the performance of slurry reactors. Iron oxide was used as slurry catalyst at a rate of 2 wt % MF coal throughout the run (dimethyl disulfide (DMDS) was used as the sulfiding agent). The close-coupled reactor unit was on-stream for 1271.2 hours for an on-stream factor of 89.8% and the ROSE-SR unit was on-feed for 1101.6 hours for an on-stream factor of 90.3% for the entire run.« less

Thin film hydrous metal oxide catalysts

DOEpatents

Dosch, Robert G.; Stephens, Howard P.

1995-01-01

Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

Adsorbate-mediated strong metal–support interactions in oxide-supported Rh catalysts

DOE PAGES

Matsubu, John C.; Zhang, Shuyi; DeRita, Leo; ...

2016-09-19

The optimization of supported metal catalysts predominantly focuses on engineering the metal site, for which physical insights based on extensive theoretical and experimental contributions have enabled the rational design of active sites. Although it is well known that supports can influence the catalytic properties of metals, insights into how metal–support interactions can be exploited to optimize metal active-site properties are lacking. Here in this paper, we utilize in situ spectroscopy and microscopy to identify and characterize a support effect in oxide-supported heterogeneous Rh catalysts. This effect is characterized by strongly bound adsorbates (HCO x) on reducible oxide supports (TiO 2more » and Nb 2O 5) that induce oxygen-vacancy formation in the support and cause HCO x-functionalized encapsulation of Rh nanoparticles by the support. The encapsulation layer is permeable to reactants, stable under the reaction conditions and strongly influences the catalytic properties of Rh, which enables rational and dynamic tuning of CO 2-reduction selectivity.« less

Attrition resistant gamma-alumina catalyst support

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2006-03-14

A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

Potential of Ni supported on KH zeolite catalysts for carbon dioxide reforming of methane

NASA Astrophysics Data System (ADS)

Kaengsilalai, Athiya; Luengnaruemitchai, Apanee; Jitkarnka, Sirirat; Wongkasemjit, Sujitra

The catalytic activity of Ni on a series of catalysts supported on the synthesized KH zeolite for the CO 2 reforming of methane has been investigated. The KH zeolite supports were previously synthesized via silatrane and alumatrane precursors using the sol-gel process and hydrothermal microwave treatment. Eight percent Ni was impregnated onto the synthesized KH zeolites, which have different morphologies: called dog-bone, flower, and disordered shapes. The prepared Ni/KH zeolites were tested for their catalytic activity at 700 °C, at atmospheric pressure, and at a CH 4/CO 2 ratio of 1. The results showed that Ni supported on dog-bone and flower-shaped KH zeolites provided better activity than that of disordered KH zeolite due to higher CH 4 and CO 2 conversions, a higher H 2 production, and a smaller amount of coke formation on the catalyst surface. Furthermore, the stability of the Ni/KH zeolite was greatly superior to that of Ni supported on alumina and clinoptiolite catalysts after 65 h on stream.

Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

NASA Technical Reports Server (NTRS)

Pisharody, Suresh A.; Fisher, John W.; Wignarajah, K.

2002-01-01

The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake of gaseous species based on their controlled pore size, high surface area, ordered chemical structure that allows functionalization and their effectiveness also as catalyst support materials for toxic gas conversion. We present results and findings from a preliminary study on the effectiveness of metal impregnated single walled nanotubes as catalyst/catalyst support materials for toxic gas contaminate control. The study included the purification of single walled nanotubes, the catalyst impregnation of the purified nanotubes, the experimental characterization of the surface properties of purified single walled nanotubes and the characterization of physisorption and chemisorption of uptake molecules.

Remarkable support effect on the reactivity of Pt/In2O3/MOx catalysts for methanol steam reforming

NASA Astrophysics Data System (ADS)

Liu, Xin; Men, Yong; Wang, Jinguo; He, Rong; Wang, Yuanqiang

2017-10-01

Effects of supports over Pt/In2O3/MOx catalysts with extremely low loading of Pt (1 wt%) and In2O3 loadings (3 wt%) are investigated for the hydrogen production of methanol steam reforming (MSR) in the temperature range of 250-400 °C. Under practical conditions without the pre-reduction, the 1Pt/3In2O3/CeO2 catalyst shows the highly efficient catalytic performance, achieving almost complete methanol conversion (98.7%) and very low CO selectivity of 2.6% at 325 °C. The supported Pt/In2O3 catalysts are characterized by means of Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), high-resolution transmission microscopy (HRTEM), temperature programmed reduction with hydrogen (H2-TPR), CO pulse chemisorption, temperature programmed desorption of methanol and water (CH3OH-TPD and H2O-TPD). These demonstrate that the nature of catalyst support of Pt/In2O3/MOx plays crucial roles in the Pt dispersion associated by the strong interaction among Pt, In2O3 and supporting materials and the surface redox properties at low temperature, and thus affects their capability to activate the reactants and determines the catalytic activity of methanol steam reforming. The superior 1Pt/3In2O3/CeO2 catalyst, exhibiting a remarkable reactivity and stability for 32 h on stream, demonstrates its potential for efficient hydrogen production of methanol steam reforming in mobile and de-centralized H2-fueled PEMFC systems.

Optimization of metal atomic ratio of PdxRuyNiz on carbon support for ethanol oxidation

NASA Astrophysics Data System (ADS)

Charoen, Kanin; Warakulwit, Chompunuch; Prapainainar, Chaiwat; Seubsai, Anusorn; Chareonpanich, Metta; Prapainainar, Paweena

2017-11-01

The catalytic activity of palladium (Pd) on an alloy catalyst on carbon supports with regards to ethanol oxidation was enhanced by systematically varying the atomic ratio of Pd, ruthenium (Ru), and nickel (Ni) alloy catalyst. Each atomic ratio catalyst was investigated so as to find the highest current density per mass of palladium. Functionalized carbon black (C) and reduced graphene oxide (rGO) were used as carbon supports. The PdxRuyNiz/carbon catalysts were prepared by impregnation and reduction method with sodium borohydride (NaBH4) being used as the reducing agent. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were used to characterize the functionalized carbon supports, and the synthesized PdxRuyNiz/carbon catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and inductively coupled plasma (ICP). The electrical properties of catalyst were performed by cyclic voltammetry (CV), chronoamperometry (CA), and CO-stripping to investigate the catalytic activity compared to 20%wt synthesized Pd/C. The results showed that Pd:Ru:Ni = 60:0:40 on rGO (Pd60Ni40/rGO) had the best metal atomic ratio and support for the electro-oxidation of ethanol. The maximum current density and the electrochemical surface area were 11,074 mA cm-2 mg-1Pd and 55.6 m2 g-1Pd, which were 1.7 and 2.67 times the corresponding values of synthesized Pd/C, respectively.

Supported transition metal catalysts for para- to ortho-hydrogen conversion

NASA Technical Reports Server (NTRS)

Brooks, Christopher J.; Wang, Wei; Eyman, Darrell P.

1994-01-01

The main goal of this study was to develop and improve on existing catalysts for the conversion of ortho- to para-hydrogen. Starting with a commercially available Air Products nickel silicate, which had a beta value of 20, we were trying to synthesize catalysts that would be an improvement to AP. This was accomplished by preparing silicates with various metals as well as different preparation methods. We also prepared supported ruthenium catalysts by various techniques using several metal precursors to improve present technology. What was also found was that the activation conditions prior to catalytic testing was highly important for both the silicates and the supported ruthenium catalysts. While not the initial focus of the research, we made some interesting observations into the adsorption of H2 on ruthenium. This helped us to get a better understanding of how ortho- to para-H2 conversion takes place, and what features in a catalyst are important to optimize activity. Reactor design was the final area in which some interesting conclusions were drawn. As discussed earlier, the reactor catalyst bed must be constructed using straight 1/8 feet OD stainless steel tubing. It was determined that the use of 1/4 feet OD tubing caused two problems. First, the radius from the center of the bed to the wall was too great for thermal equilibrium. Since the reaction of ortho- to para-H2 is exothermic, the catalyst bed center was warmer than the edges. Second, the catalyst bed was too shallow using a 1/4 feet tube. This caused reactant blow-by which was thought to decrease the measured activity when the flow rate was increased. The 1/8 feet tube corrected both of these concerns.

Process for the generation of .alpha., .beta.-unsaturated carboxylic acids and esters using niobium catalyst

DOEpatents

Gogate, Makarand Ratnakav; Spivey, James Jerome; Zoeller, Joseph Robert

1999-01-01

A process using a niobium catalyst includes the step of reacting an ester or carboxylic acid with oxygen and an alcohol in the presence a niobium catalyst to respectively produce an .alpha.,.beta.-unsaturated ester or carboxylic acid. Methanol may be used as the alcohol, and the ester or carboxylic acid may be passed over the niobium catalyst in a vapor stream containing oxygen and methanol. Alternatively, the process using a niobium catalyst may involve the step of reacting an ester and oxygen in the presence the niobium catalyst to produce an .alpha.,.beta.-unsaturated carboxylic acid. In this case the ester may be a methyl ester. In either case, niobium oxide may be used as the niobium catalyst with the niobium oxide being present on a support. The support may be an oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide and mixtures thereof. The catalyst may be formed by reacting niobium fluoride with the oxide serving as the support. The niobium catalyst may contain elemental niobium within the range of 1 wt % to 70 wt %, and more preferably within the range of 10 wt % to 30 wt %. The process may be operated at a temperature from 150 to 450.degree. C. and preferably from 250 to 350.degree. C. The process may be operated at a pressure from 0.1 to 15 atm. absolute and preferably from 0.5-5 atm. absolute. The flow rate of reactants may be from 10 to 10,000 L/kg.sub.(cat) /h, and preferably from 100 to 1,000 L/kg.sub.(cat) /h.

Catalyst and electrode research for phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Antoine, A. C.; King, R. B.

1987-01-01

An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst supports. Efforts to improve cell performance and reduce catalyst costs have led to the investigation of a class of organometallic cathode catalysts represented by the tetraazaannulenes, and a mixed catalyst which is a mixture of carbons catalyzed with an organometallic and a noble metal.

Nickel/ruthenium catalyst and method for aqueous phase reactions

DOEpatents

Elliott, D.C.; Sealock, J.L.

1998-09-29

A method of hydrogenation is described using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions. 2 figs.

Electrocatalyst for alcohol oxidation in fuel cells

DOEpatents

Adzic, Radoslav R.; Marinkovic, Nebojsa S.

2001-01-01

Binary and ternary electrocatalysts are provided for oxidizing alcohol in a fuel cell. The binary electrocatalyst includes 1) a substrate selected from the group consisting of NiWO.sub.4 or CoWO.sub.4 or a combination thereof, and 2) Group VIII noble metal catalyst supported on the substrate. The ternary electrocatalyst includes 1) a substrate as described above, and 2) a catalyst comprising Group VIII noble metal, and ruthenium oxide or molybdenum oxide or a combination thereof, said catalyst being supported on said substrate.

Nickel/ruthenium catalyst and method for aqueous phase reactions

DOEpatents

Elliott, Douglas C.; Sealock, John L.

1998-01-01

A method of hydrogenation using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions.

Catalyst and method for aqueous phase reactions

DOEpatents

Elliott, Douglas C.; Hart, Todd R.

1999-01-01

The present invention is a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional metal deposited onto the support in a second dispersed phase. The additional metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase without substantially affecting the catalytic activity, thereby increasing the life time of the catalyst.

Supported catalysts using nanoparticles as the support material

DOEpatents

Wong, Michael S.; Wachs, Israel E.; Knowles, William V.

2010-11-02

A process for making a porous catalyst, comprises a) providing an aqueous solution containing a nanoparticle precursor, b) forming a composition containing nanoparticles, c) adding a first catalytic component or precursor thereof and a pore-forming agent to the composition containing nanoparticles and allowing the first catalytic component, the pore-forming agent, and the nanoparticles form an organic-inorganic structure, d) removing water from the organic-inorganic structure; and e) removing the pore-forming agent from the organic-inorganic structure so as to yield a porous catalyst.

Sulfur poisoning of CeO[subscript 2]-Al[subscript 2]O[subscript 3]-supported mono- and bi-metallic Ni and Rh catalysts in steam reforming of liquid hydrocarbons at low and high temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Chao; Chen, Yongsheng; Li, Yan

2010-12-01

In order to develop a better understanding on sulfur poisoning of reforming catalysts in fuel processing for hydrogen production, steam reforming of liquid hydrocarbons was performed over CeO{sub 2}-Al{sub 2}O{sub 3} supported monometallic Ni and Rh and bimetallic Rh-Ni catalysts at 550 and 800 C. XANES was used to identify the sulfur species in the used catalysts and to study their impacts on the metal surface properties probed by XPS. It was found that both monometallic catalysts rapidly deactivated at 550 C, and showed poor sulfur tolerance. Although ineffective for the Ni catalyst, increasing the temperature to 800 C dramaticallymore » improved the sulfur tolerance of the Rh catalyst. XANES revealed that metal sulfide and organic sulfide are the dominant sulfur species on the used Ni catalyst, while sulfonate and sulfate predominate on the used Rh catalyst. The presence of sulfur induced severe carbon deposition on the Ni catalyst at 800 C. The superior sulfur tolerance of the Rh catalyst at 800 C may be associated with its capability in sulfur oxidation. It is likely that the formation of the oxygen-shielded sulfur structure of sulfonate and sulfate can suppress the poisoning impact of sulfur on Rh by inhibiting direct rhodium-sulfur interaction. Moreover, XPS indicated that the metal surface properties of the Rh catalysts after the reaction without and with sulfur at 800 C are similar, suggesting that sulfur poisoning on Rh was mitigated under the high-temperature condition. Although the Rh-Ni catalyst exhibited better sulfur tolerance than the monometallic catalysts at 550 C, its catalytic performance was inferior compared with the Rh catalyst in the sulfur-containing reaction at 800 C probably due to the severe carbon deposition on the bimetallic catalyst.« less

Cobalt Fischer-Tropsch catalysts having improved selectivity

DOEpatents

Miller, James G.; Rabo, Jule A.

1989-01-01

A cobalt Fischer-Tropsch catalyst having an improved steam treated, acid extracted LZ-210 support is taught. The new catalyst system demonstrates improved product selectivity at Fischer-Tropsch reaction conditions evidenced by lower methane production, higher C.sub.5.sup.+ yield and increased olefin production.