Solvent-free and catalyst-free chemistry: A benign pathway to sustainability

EPA Science Inventory

In the past decade, alternative benign organic methodologies have become an imperative part of organic syntheses and novel chemical reactions. The various new and innovative sustainable organic reactions and methodologies using no solvents or catalysts and employing alternative ...

Covalent Immobilization of (-)-Riboflavin on Polymer Functionalized Silica Particles: Application in the Photocatalytic E→Z Isomerization of Polarized Alkenes.

PubMed

Metternich, Jan B; Sagebiel, Sven; Lückener, Anne; Lamping, Sebastian; Ravoo, Bart Jan; Gilmour, Ryan

2018-03-20

The covalent immobilization of the biomimetic, photo-organocatalyst (-)-riboflavin on silica micro- and nanoparticles via atom transfer radical polymerization (ATRP) is disclosed. Given the effectiveness of (-)-riboflavin as a versatile, environmentally benign photocatalyst, an immobilization strategy based on acrylate-linker modification of the catalyst core and controlled polymerization on initiator pre-functionalized silica particles has been developed. Validation of this approach is demonstrated in the E→Z isomerization of a benchmark cinnamonitrile (Z/E up to 88:12) with 0.97 mol % catalyst loading. Characterization of the immobilized photocatalyst supports covalent embedding of the catalyst in the polymeric brushes on the silica particle surface. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sustainable utilization of waste palm oil and sulfonated carbon catalyst derived from coconut meal residue for biodiesel production.

PubMed

Thushari, Indika; Babel, Sandhya

2018-01-01

In this study, an inexpensive, environmental benign acid catalyst is prepared using coconut meal residue (CMR) and employed for biodiesel production from waste palm oil (WPO). The total acid density of the catalyst is found to be 3.8mmolg -1 . The catalyst shows a unique amorphous structure with 1.33m 2 g -1 of surface area and 0.31cm 3 g -1 of mean pore volume. Successful activation is confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The highest biodiesel yield of 92.7% was obtained from WPO in an open reflux system using the catalyst. Results show that biodiesel yield increases with increasing methanol:oil (molar ratio) and reaction time up to an optimum value. It is found that the catalyst can be reused for at least four cycles for >80% biodiesel yield. Fuel properties of the produced biodiesel meet international biodiesel standards. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Nata, Iryanti Fatyasari, E-mail: yanti_tkunlam@yahoo.com; Irawan, Chairul; Mardina, Primata

Highly sulfonated carbonaceous spheres with diameter of 100–500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO{sub 3}H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO{sub 3}H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRSmore » concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst. - Highlights: • Carbon solid acid was successfully prepared by one-step hydrothermal carbonization. • The acrylic acid as monomer was effectively reduce the diameter size of particle. • The solid acid catalyst show good catalytic performance of starch hydrolysis. • The solid acid catalyst is not significantly deteriorated after repeated use.« less

Hybrid Amine-Functionalized Graphene Oxide as a Robust Bifunctional Catalyst for Atmospheric Pressure Fixation of Carbon Dioxide using Cyclic Carbonates.

PubMed

Saptal, Vitthal B; Sasaki, Takehiko; Harada, Kei; Nishio-Hamane, Daisuke; Bhanage, Bhalchandra M

2016-03-21

An environmentally-benign carbocatalyst based on amine-functionalized graphene oxide (AP-GO) was synthesized and characterized. This catalyst shows superior activity for the chemical fixation of CO2 into cyclic carbonates at the atmospheric pressure. The developed carbocatalyst exhibits superior activity owing to its large surface area with abundant hydrogen bonding donor (HBD) capability and the presence of well-defined amine functional groups. The presence of various HBD and amine functional groups on the graphene oxide (GO) surface yields a synergistic effect for the activation of starting materials. Additionally, this catalyst shows high catalytic activity to synthesize carbonates at 70 °C and at 1 MPa CO2 pressure. The developed AP-GO could be easily recovered and used repetitively in up to seven recycle runs with unchanged catalyst activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biosupported Bimetallic Pd Au Nanocatalysts for Dechlorination of Environmental Contaminants

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

De Corte, S.; Fitts, J.; Hennebel, T.

2011-08-30

Biologically produced monometallic palladium nanoparticles (bio-Pd) have been shown to catalyze the dehalogenation of environmental contaminants, but fail to efficiently catalyze the degradation of other important recalcitrant halogenated compounds. This study represents the first report of biologically produced bimetallic Pd/Au nanoparticle catalysts. The obtained catalysts were tested for the dechlorination of diclofenac and trichloroethylene. When aqueous bivalent Pd(II) and trivalent Au(III) ions were both added to concentrations of 50 mg L{sup -1} and reduced simultaneously by Shewanella oneidensis in the presence of H{sub 2}, the resulting cell-associated bimetallic nanoparticles (bio-Pd/Au) were able to dehalogenate 78% of the initially added diclofenacmore » after 24 h; in comparison, no dehalogenation was observed using monometallic bio-Pd or bio-Au. Other catalyst-synthesis strategies did not show improved dehalogenation of TCE and diclofenac compared with bio-Pd. Synchrotron-based X-ray diffraction, (scanning) transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the simultaneous reduction of Pd and Au supported on cells of S. oneidensis resulted in the formation of a unique bimetallic crystalline structure. This study demonstrates that the catalytic activity and functionality of possibly environmentally more benign biosupported Pd-catalysts can be improved by coprecipitation with Au.« less

Controllable cyanation of carbon-hydrogen bonds by zeolite crystals over manganese oxide catalyst

PubMed Central

Wang, Liang; Wang, Guoxiong; Zhang, Jian; Bian, Chaoqun; Meng, Xiangju; Xiao, Feng-Shou

2017-01-01

The synthesis of organic nitriles without using toxic cyanides is in great demand but challenging to make. Here we report an environmentally benign and cost-efficient synthesis of nitriles from the direct oxidative cyanation of primary carbon-hydrogen bonds with easily available molecular oxygen and urea. The key to this success is to design and synthesize manganese oxide catalysts fixed inside zeolite crystals, forming a manganese oxide catalyst with zeolite sheath (MnOx@S-1), which exhibits high selectivity for producing nitriles by efficiently facilitating the oxidative cyanation reaction and hindering the side hydration reaction. The work delineates a sustainable strategy for synthesizing nitriles while avoiding conventional toxic cyanide, which might open a new avenue for selective transformation of carbon-hydrogen bonds. PMID:28504259

Advanced Materials by Atom Transfer Radical Polymerization.

PubMed

Matyjaszewski, Krzysztof

2018-06-01

Atom transfer radical polymerization (ATRP) has been successfully employed for the preparation of various advanced materials with controlled architecture. New catalysts with strongly enhanced activity permit more environmentally benign ATRP procedures using ppm levels of catalyst. Precise control over polymer composition, topology, and incorporation of site specific functionality enables synthesis of well-defined gradient, block, comb copolymers, polymers with (hyper)branched structures including stars, densely grafted molecular brushes or networks, as well as inorganic-organic hybrid materials and bioconjugates. Examples of specific applications of functional materials include thermoplastic elastomers, nanostructured carbons, surfactants, dispersants, functionalized surfaces, and biorelated materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave-promoted catalyst- and solvent-free aza-Diels-Alder reaction of aldimines with 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil.

PubMed

Sarma, Rupam; Sarmah, Manas M; Prajapati, Dipak

2012-02-17

A microwave-promoted aza-Diels-Alder reaction between 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil and aldimines has been developed for the construction of dihydropyrido[4,3-d]pyrimidines. Urea is effectively employed as an environmentally benign source of ammonia in the absence of any catalyst or solvent. The key step in the reaction is in situ generation and trapping of the reactive aldimine formed from urea and aldehyde by the diene system of the uracil. The reaction is clean, and excellent yields are obtained in a matter of a few minutes.

Cobalt-catalyzed hydrogenation of esters to alcohols: unexpected reactivity trend indicates ester enolate intermediacy.

PubMed

Srimani, Dipankar; Mukherjee, Arup; Goldberg, Alexander F G; Leitus, Gregory; Diskin-Posner, Yael; Shimon, Linda J W; Ben David, Yehoshoa; Milstein, David

2015-10-12

The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts, with few exceptions. Presented here is the first cobalt-catalyzed hydrogenation of esters to the corresponding alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterogeneous catalysis: Enigmas, illusions, challenges, realities, and emergent strategies of design

NASA Astrophysics Data System (ADS)

Thomas, John Meurig

2008-05-01

Predominantly this article deals with the question of how to design new solid catalysts for a variety of industrial and laboratory-orientated purposes. A generally applicable strategy, illustrated by numerous examples, is made possible based on the use of nanoporous materials on to the (high-area) inner surfaces of which well-defined (experimentally and computationally) active centers are placed in a spatially separated fashion. Such single-site catalysts, which have much in common with metal-centered homogenous catalysts and enzymes, enable a wide range of new catalysts to be designed for a variety of selective oxidations, hydrogenations, hydrations and hydrodewaxing, and other reactions that the "greening" of industrial processes demand. Examples are given of new shape-selective, regio-selective, and enantioselective catalysts, many of which operate under mild, environmentally benign conditions. Also considered are some of the reasons why detailed studies of adsorption and stoichiometric reactions at single-crystal surfaces have, disappointingly, not hitherto paved the way to the design and production of many new heterogenous catalysts. Recent work of a theoretical and high-throughout nature, allied to some experimental studies of well-chosen model systems, holds promise for the identification of new catalysts for simple, but industrially important reactions.

Synthesis and Characterization of AlCl3 Impregnated Molybdenum Oxide as Heterogeneous Nano-Catalyst for the Friedel-Crafts Acylation Reaction in Ambient Condition.

PubMed

Jadhav, Arvind H; Chinnappan, Amutha; Hiremath, Vishwanath; Seo, Jeong Gil

2015-10-01

Aluminum trichloride (AlCl3) impregnated molybdenum oxide heterogeneous nano-catalyst was prepared by using simple impregnation method. The prepared heterogeneous catalyst was characterized by powder X-ray diffraction, FT-IR spectroscopy, solid-state NMR spectroscopy, SEM imaging, and EDX mapping. The catalytic activity of this protocol was evaluated as heterogeneous catalyst for the Friedel-Crafts acylation reaction at room temperature. The impregnated MoO4(AlCl2)2 catalyst showed tremendous catalytic activity in Friedel-Crafts acylation reaction under solvent-free and mild reaction condition. As a result, 84.0% yield of acyl product with 100% consumption of reactants in 18 h reaction time at room temperature was achieved. The effects of different solvents system with MoO4(AlCl2)2 catalyst in acylation reaction was also investigated. By using optimized reaction condition various acylated derivatives were prepared. In addition, the catalyst was separated by simple filtration process after the reaction and reused several times. Therefore, heterogeneous MoO4(AlCl2)2 catalyst was found environmentally benign catalyst, very convenient, high yielding, and clean method for the Friedel-Crafts acylation reaction under solvent-free and ambient reaction condition.

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

Gewirth, Andrew A.; Kenis, Paul J.; Nuzzo, Ralph G.

In this research, we prosecuted a comprehensive plan of research directed at developing new catalysts and new understandings relevant to the operation of low temperature hydrogen-oxygen fuel cells. The focal point of this work was one centered on the Oxygen Reduction Reaction (ORR), the electrochemical process that most fundamentally limits the technological utility of these environmentally benign energy conversion devices. Over the period of grant support, we developed new ORR catalysts, based on Cu dimers and multimers. In this area, we developed substantial new insight into design rules required to establish better ORR materials, inspired by the three-Cu active sitemore » in laccase which has the highest ORR onset potential of any material known. We also developed new methods of characterization for the ORR on conventional (metal-based) catalysts. Finally, we developed a new platform to study the rate of proton transfer relevant to proton coupled electron transfer (PCET) reactions, of which the ORR is an exemplar. Other aspects of work involved theory and prototype catalyst testing.« less

In situ Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines.

PubMed

Cheng, Hua; Xiong, Mao-Qian; Cheng, Chuan-Xiang; Wang, Hua-Jing; Lu, Qiang; Liu, Hong-Fu; Yao, Fu-Bin; Chen, Cheng; Verpoort, Francis

2018-02-16

The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, in situ generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=-7.8 ppm in the 1 H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalyst-free activation of methylene chloride and alkynes by amines in a three-component coupling reaction to synthesize propargylamines.

PubMed

Rawat, Vikas S; Bathini, Thulasiram; Govardan, S; Sreedhar, Bojja

2014-09-14

Propargylamines are synthesized via metal-free activation of the C-halogen bond of dihalomethanes and the C-H bond of terminal alkynes in a three-component coupling without catalyst or additional base and under mild reaction conditions. The dihalomethanes are used both as solvents as well as precursors for the methylene fragment (C1) in the final product. The scope of the reaction and the influence of various reaction variables has been investigated. A plausible reaction mechanism is proposed and the involvement of various intermediates that can be generated in situ in the process is discussed. The metal-free conditions also make this protocol environmentally benign and atom economical.

Metal-Organic Framework-Stabilized CO2/Water Interfacial Route for Photocatalytic CO2 Conversion.

PubMed

Luo, Tian; Zhang, Jianling; Li, Wei; He, Zhenhong; Sun, Xiaofu; Shi, Jinbiao; Shao, Dan; Zhang, Bingxing; Tan, Xiuniang; Han, Buxing

2017-11-29

Here, we propose a CO 2 /water interfacial route for photocatalytic CO 2 conversion by utilizing a metal-organic framework (MOF) as both an emulsifier and a catalyst. The CO 2 reduction occurring at the CO 2 /water interface produces formate with remarkably enhanced efficiency as compared with that in conventional solvent. The route is efficient, facile, adjustable, and environmentally benign, which is applicable for the CO 2 transformation photocatalyzed by different kinds of MOFs.

Nano-catalysts with Magnetic Core: Sustainable Options for Greener Synthesis

EPA Science Inventory

Author’s perspective on nano-catalysts with magnetic core is summarized with recent work from his laboratory. Magnetically recyclable nano-catalysts and their use in benign media is an ideal blend for the development of sustainable methodologies in organic synthesis. Water or pol...

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...

Biodiesel synthesis by TiO2-ZnO mixed oxide nanocatalyst catalyzed palm oil transesterification process.

PubMed

Madhuvilakku, Rajesh; Piraman, Shakkthivel

2013-12-01

Biodiesel is a promising alternating environmentally benign fuel to mineral diesel. For the development of easier transesterification process, stable and active heterogeneous mixed metal oxide of TiO2-ZnO and ZnO nanocatalysts were synthesized and exploited for the palm oil transesterification process. The synthesized catalysts were characterized by XRD, FT-IR, and FE-SEM studies for their structural and morphological characteristics. It was found that TiO2-ZnO nanocatalyst exhibits good catalytic activity and the catalytic performance was greatly depends on (i) catalyst concentration (ii) methanol to oil molar ratio (iii) reaction temperature and (iv) reaction time. A highest 98% of conversion was obtained at the optimum reaction parameters with 200 mg of catalyst loading and the biodiesel was analyzed by TLC and (1)H NMR techniques. The TiO2-ZnO nanocatalyst shows good catalytic performance over the ZnO catalyst, which could be a potential candidate for the large-scale biodiesel production from palm oil at the reduced temperature and time. Copyright © 2013. Published by Elsevier Ltd.

A simple and facile Heck-type arylation of alkenes with diaryliodonium salts using magnetically recoverable Pd-catalyst

EPA Science Inventory

The Heck-type arylation of alkenes was achieved in aqueous polyethylene glycol using a magnetically recoverable heterogenized palladium catalyst employing diaryliodonium salts under ambient conditions. The benign reaction medium and the stability of the catalyst are the salient f...

A highly active and magnetically retrievable nanoferrite-DOPA-copper catalyst for the coupling of thiophenols with aryl halides

EPA Science Inventory

Diaryl sulfides were synthesized using magnetically recoverable heterogeneous Cu catalyst via one-pot multi component reaction using MW irradiation; the use of isopropanol as a benign reaction medium, easy recovery of the catalyst using an external magnet, efficient recycling...

Ferrocene-modified chitosan as an efficient and green heterogeneous catalyst for sulfate-radical-based advanced oxidation process.

PubMed

Lin, Kun-Yi Andrew; Lin, Jyun-Ting; Yang, Hongta

2017-10-01

While ferrocene (Fc) is a promising heterogeneous catalyst for activating persulfate (PS) to degrade organic contaminants, chemical reagent-grade Fc is nanoscale and direct usage of Fc leads to operational and recovery issues. In this study, chitosan (CS) is selected as a support to immobilize Fc as CS is abundant, and environmental benign fishery waste. The amine group of CS also allows the formation of covalent bond between Fc-based reagent (i.e., Fc-CHO) and CS to form Fc-modified CS (Fc-CS). This Fc-CS can be more advantageous than Fc because of its easier recovery by precipitation and filtration. To evaluate Fc-CS for PS activation, degradation of Amaranth (AMR) dye by PS is selected as a model test. The resulting Fc-CS exhibits a higher catalytic activity than pristine Fc possibly because Fc can be evenly dispersed on CS and CS can also exhibit affinity toward AMR. AMR can be also fully decomposed by Fc-CS activated PS. Through the Electron paramagnetic resonance (EPR) spectroscopic analysis, the AMR degradation can be attributed to both sulfate and hydroxyl radicals. Fc-CS had been also proven to activate PS for AMR degradation over multiple times without loss of catalytic activity. These features indicate that Fc-CS can be a promising catalyst and CS appears to be a naturally available and environmentally friendly waste-derived support for immobilizing Fc. The results and findings in this study are essential for CS-supported metal catalysts in environmental applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pd-Catalyzed Heterocycle Synthesis in Ionic Liquids

NASA Astrophysics Data System (ADS)

Li, Jianxiao; Jiang, Huanfeng

Heterocyclic and fused heterocyclic compounds are ubiquitously found in natural products and biologically interesting molecules, and many currently marketed drugs hold heterocycles as their core structure. In this chapter, recent advances on Pd-catalyzed synthesis of heterocycles in ionic liquids (ILs) are reviewed. In palladium catalysis, ILs with different cations and anions are investigated as an alternative recyclable and environmentally benign reaction medium, and a variety of heterocyclic compounds including cyclic ketals, quinolones, quinolinones, isoindolinones, and lactones are conveniently constructed. Compared to the traditional methods, these new approaches have many advantages, such as environmentally friendly synthetic procedure, easy product and catalyst separation, recyclable medium, which make them have the potential applications in industry.

Recent advances in transition metal-catalyzed N -atom transfer reactions of azides

PubMed Central

Driver, Tom G.

2011-01-01

Transition metal-catalyzed N-atom transfer reactions of azides provide efficient ways to construct new carbon–nitrogen and sulfur–nitrogen bonds. These reactions are inherently green: no additive besides catalyst is needed to form the nitrenoid reactive intermediate, and the by-product of the reaction is environmentally benign N2 gas. As such, azides can be useful precursors for transition metal-catalyzed N-atom transfer to sulfides, olefins and C–H bonds. These methods offer competitive selectivities and comparable substrate scope as alternative processes to generate metal nitrenoids. PMID:20617243

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.

Pre-converted nitric oxide gas in catalytic reduction system

DOEpatents

Hsiao, Mark C.; Merritt, Bernard T.; Penetrante, Bernardino M.; Vogtlin, George E.

1999-01-01

A two-stage catalyst comprises an oxidative first stage and a reductive second stage. The first stage is intended to convert NO to NO.sub.2 in the presence of O.sub.2. The second stage serves to convert NO.sub.2 to environmentally benign gases that include N2, CO2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber. An oxidizing first catalyst converts NO to NO.sub.2 in the presence of O.sub.2 and includes platinum/alumina, e.g., Pt/Al.sub.2 O.sub.3 catalyst. A flow of hydrocarbons (C.sub.x H.sub.y) is input from a pipe into a second chamber. For example, propene can be used as a source of hydrocarbons. The NO.sub.2 from the first catalyst mixes with the hydrocarbons in the second chamber. The mixture proceeds to a second reduction catalyst that converts NO.sub.2 to N2, CO2, and H.sub.2 O, and includes a gamma-alumina .gamma.-Al.sub.2 O.sub.3. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the second catalyst.

Pre-converted nitric oxide gas in catalytic reduction system

DOEpatents

Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.

1999-04-06

A two-stage catalyst comprises an oxidative first stage and a reductive second stage. The first stage is intended to convert NO to NO{sub 2} in the presence of O{sub 2}. The second stage serves to convert NO{sub 2} to environmentally benign gases that include N{sub 2}, CO{sub 2}, and H{sub 2}O. By preconverting NO to NO{sub 2} in the first stage, the efficiency of the second stage for NO{sub x} reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber. An oxidizing first catalyst converts NO to NO{sub 2} in the presence of O{sub 2} and includes platinum/alumina, e.g., Pt/Al{sub 2}O{sub 3} catalyst. A flow of hydrocarbons (C{sub x}H{sub y}) is input from a pipe into a second chamber. For example, propene can be used as a source of hydrocarbons. The NO{sub 2} from the first catalyst mixes with the hydrocarbons in the second chamber. The mixture proceeds to a second reduction catalyst that converts NO{sub 2} to N{sub 2}, CO{sub 2}, and H{sub 2}O, and includes a {gamma}-Al{sub 2}O{sub 3}. The hydrocarbons and NO{sub x} are simultaneously reduced while passing through the second catalyst. 9 figs.

BBD Optimization of K-ZnO Catalyst Modification Process for Heterogeneous Transesterification of Rice Bran Oil to Biodiesel

NASA Astrophysics Data System (ADS)

Kabo, K. S.; Yacob, A. R.; Bakar, W. A. W. A.; Buang, N. A.; Bello, A. M.; Ruskam, A.

2016-07-01

Environmentally benign zinc oxide (ZnO) was modified with 0-15% (wt.) potassium through wet impregnation and used in transesterification of rice bran oil (RBO) to form biodiesel. The catalyst was characterized by X-Ray powder Diffraction (XRD), its basic sites determined by back titration and Response Surface Methodology (RSM) Box-Behnken Design (BBD) was used to optimize the modification process variables on the basic sites of the catalyst. The transesterification product, biodiesel was analyzed by Nuclear Magnetic Resonance (NMR) spectroscopy. The result reveals K-modified ZnO with highly increased basic sites. Quadratic model with high regression R2 = 0.9995 was obtained from the ANOVA of modification process, optimization at maximum basic sites criterion gave optimum modification conditions of K-loading = 8.5% (wt.), calcination temperature = 480 oC and time = 4 hours with response and basic sites = 8.14 mmol/g which is in close agreement with the experimental value of 7.64 mmol/g. The catalyst was used and a value of 95.53% biodiesel conversion was obtained and effect of potassium leaching was not significant in the process

Organic synthesis via magnetic attraction: benign and sustainable protocols using magnetic nanoferrites

EPA Science Inventory

Magnetic nano-catalysts have been prepared using simple modification of iron ferrites wherein their quasi-homogeneous state, because of nm size range, facilitates the catalysis process as increased surface is available for reaction; the easy separation of the catalysts by externa...

Efficient catalytic system for the direct transformation of lignocellulosic biomass to furfural and 5-hydroxymethylfurfural.

PubMed

Zhang, Luxin; Xi, Guoyun; Zhang, Jiaxin; Yu, Hongbing; Wang, Xiaochang

2017-01-01

A feasible approach was developed for the co-production of 5-hydroxymethylfurfural (5-HMF) and furfural from corncob via a new porous polytriphenylamine-SO 3 H (SPTPA) solid acid catalyst in lactone solvents. XRD, SEM, XPS, N 2 adsorption-desorption, elemental analysis, TG-DTA, acid-base titration and FTIR spectroscopy techniques were used to characterize the catalyst. This study demonstrates and optimizes the catalytic performance of SPTPA and solvent selection. SPTPA was found to exhibit superior catalytic ability in γ-valerolactone (GVL). Under the optimum reaction conditions, simultaneously encouraging yields of furfural (73.9%) and 5-HMF (32.3%) were achieved at 448K. The main advantages of this process include reasonable yields of both 5-HMF and furfural in the same reaction system, practical simplicity for the raw biomass utilization, and the use of a safe and environmentally benign solvent. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Zhang, T.; Hu, M.; Guo, Q.

Here we report a study of printing of electronics using an office use laser printer. The proposed method eliminates those critical disadvantages of solvent-based printing techniques by taking the advantages of electroless deposition and laser printing. The synthesized toner acts as a catalyst for the electroless copper deposition as well as an adhesion-promoting buffer layer between the substrate and deposited copper. The easy metallization of printed patterns and strong metal-substrate adhesion make it an especially effective method for massive production of flexible printed circuits. The proposed process is a high throughput, low cost, efficient, and environmentally benign method for flexiblemore » electronics manufacturing.« less

Benign by design: catalyst-free in-water, on-water green chemical methodologies in organic synthesis

EPA Science Inventory

The development of organic synthesis under sustainable conditions is a primary goal of practicing green chemists who want to prevent pollution and design safer pathways. Although, it is challenging to avoid the use of catalysts, or solvents in all the organic reactions but progre...

Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.

PubMed

Zavahir, Sifani; Zhu, Huaiyong

2015-01-26

Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds.

Silica nanosphere-supported palladium(II) furfural complex as a highly efficient and recyclable catalyst for oxidative amination of aldehydes.

PubMed

Sharma, R K; Sharma, Shivani

2014-01-21

The present work reports the fabrication of a novel and highly efficient silica nanospheres-based palladium catalyst (SiO2@APTES@Pd-FFR) via immobilization of a palladium complex onto silica nanospheres functionalized with 3-aminopropyltriethoxysilane (APTES), and its catalytic application for the oxidative amination of aldehydes to yield commercially important amides. The structure of the nano-catalyst was confirmed by Solid-state (13)C CPMAS and (29)Si CPMAS NMR spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy (FT-IR), Energy dispersive X-ray fluorescence spectroscopy (ED-XRF), Atomic absorption spectroscopy (AAS), Transmission electron microscopy (TEM) and elemental analysis. The nano-catalyst was found to be highly effective for the oxidative amination of aldehydes using hydrogen peroxide as an environmentally benign oxidant to give amides. The effect of various reaction parameters such as temperature, amount of catalyst, reaction time, type of solvent, oxidant used, substrate to oxidant ratio etc. have been demonstrated to achieve high catalytic efficacy. Moreover, this nanostructured catalyst could be recovered with simplicity and reused for several cycles without any significant loss in its catalytic activity. In addition, the stability of the reused nano-catalyst was proved by FT-IR and HRTEM techniques. It is worth noting that the features of mild reaction conditions, simple work-up procedure, high product yield, no use of toxic organic solvents, high turn-over frequency (TOF), and easy recovery and reusability of the present quasi-homogeneous nano-catalyst make this protocol an attractive alternative to the existing catalytic methods for the oxidative amination of aldehydes to furnish industrially important amides.

Greener Route for Synthesis of aryl and alkyl-14H-dibenzo [a.j] xanthenes using Graphene Oxide-Copper Ferrite Nanocomposite as a Recyclable Heterogeneous Catalyst

NASA Astrophysics Data System (ADS)

Kumar, Aniket; Rout, Lipeeka; Achary, Lakkoji Satish Kumar; Dhaka, Rajendra. S.; Dash, Priyabrat

2017-02-01

A facile, efficient and environmentally-friendly protocol for the synthesis of xanthenes by graphene oxide based nanocomposite (GO-CuFe2O4) has been developed by one-pot condensation route. The nanocomposite was designed by decorating copper ferrite nanoparticles on graphene oxide (GO) surface via a solution combustion route without the use of template. The as-synthesized GO-CuFe2O4 composite was comprehensively characterized by XRD, FTIR, Raman, SEM, EDX, HRTEM with EDS mapping, XPS, N2 adsorption-desorption and ICP-OES techniques. This nanocomposite was then used in an operationally simple, cost effective, efficient and environmentally benign synthesis of 14H-dibenzo xanthene under solvent free condition. The present approach offers several advantages such as short reaction times, high yields, easy purification, a cleaner reaction, ease of recovery and reusability of the catalyst by a magnetic field. Based upon various controlled reaction results, a possible mechanism for xanthene synthesis over GO-CuFe2O4 catalyst was proposed. The superior catalytic activity of the GO-CuFe2O4 nanocomposite can be attributed to the synergistic interaction between GO and CuFe2O4 nanoparticles, high surface area and presence of small sized CuFe2O4 NPs. This versatile GO-CuFe2O4 nanocomposite synthesized via combustion method holds great promise for applications in wide range of industrially important catalytic reactions.

Novel Acid Catalysts from Waste-Tire-Derived Carbon: Application in Waste-to-Biofuel Conversion

DOE PAGES

Hood, Zachary D.; Adhikari, Shiba P.; Li, Yunchao; ...

2017-06-21

Many inexpensive biofuel feedstocks, including those containing free fatty acids (FFAs) in high concentrations, are typically disposed of as waste due to our inability to efficiently convert them into usable biofuels. Here we demonstrate that carbon derived from waste tires could be functionalized with sulfonic acid (-SO 3H) to effectively catalyze the esterification of oleic acid or a mixture of fatty acids to usable biofuels. Waste tires were converted to hard carbon, then functionalized with catalytically active -SO 3H groups on the surface through an environmentally benign process that involved the sequential treatment with L-cysteine, dithiothreitol, and H 2O 2.more » In conclusion, when benchmarked against the same waste-tire derived carbon material treated with concentrated sulfuric acid at 150 °C, similar catalytic activity was observed. Both catalysts could also effectively convert oleic acid or a mixture of fatty acids and soybean oil to usable biofuels at 65 °C and 1 atm without leaching of the catalytic sites.« less

OMS-2-Supported Cu Hydroxide-Catalyzed Benzoxazoles Synthesis from Catechols and Amines via Domino Oxidation Process at Room Temperature.

PubMed

Meng, Xu; Wang, Yanmin; Wang, Yuanguang; Chen, Baohua; Jing, Zhenqiang; Chen, Gexin; Zhao, Peiqing

2017-07-07

In the presence of manganese oxide octahedral molecular sieve (OMS-2) supported copper hydroxide Cu(OH) x /OMS-2, aerobic synthesis of benzoxazoles from catechols and amines via domino oxidation/cyclization at room temperature is achieved. This heterogeneous benzoxazoles synthesis initiated by the efficient oxidation of catechols over Cu(OH) x /OMS-2 tolerates a variety of substrates, especially amines containing sensitive groups (hydroxyl, cyano, amino, vinyl, ethynyl, ester, and even acetyl groups) and heterocycles, which affords functionalized benzoxazoles in good to excellent yields by employing low catalyst loading (2 mol % Cu). The characterization and plausible catalytic mechanism of Cu(OH) x /OMS-2 are described. The notable features of our catalytic protocol such as the use of air as the benign oxidant and EtOH as the solvent, mild conditions, ease of product separation, being scalable up to the gram level, and superior reusability of catalyst (up to 10 cycles) make it more practical and environmentally friendly for organic synthesis.

Locus-specific microemulsion catalysts for sulfur mustard (HD) chemical warfare agent decontamination.

PubMed

Fallis, Ian A; Griffiths, Peter C; Cosgrove, Terence; Dreiss, Cecile A; Govan, Norman; Heenan, Richard K; Holden, Ian; Jenkins, Robert L; Mitchell, Stephen J; Notman, Stuart; Platts, Jamie A; Riches, James; Tatchell, Thomas

2009-07-22

The rates of catalytic oxidative decontamination of the chemical warfare agent (CWA) sulfur mustard (HD, bis(2-chlororethyl) sulfide) and a range (chloroethyl) sulfide simulants of variable lipophilicity have been examined using a hydrogen peroxide-based microemulsion system. SANS (small-angle neutron scattering), SAXS (small-angle X-ray scattering), PGSE-NMR (pulsed-gradient spin-echo NMR), fluorescence quenching, and electrospray mass spectroscopy (ESI-MS) were implemented to examine the distribution of HD, its simulants, and their oxidation/hydrolysis products in a model oil-in-water microemulsion. These measurements not only present a means of interpreting decontamination rates but also a rationale for the design of oxidation catalysts for these toxic materials. Here we show that by localizing manganese-Schiff base catalysts at the oil droplet-water interface or within the droplet core, a range of (chloroethyl) sulfides, including HD, spanning some 7 orders of octanol-water partition coefficient (K(ow)), may be oxidized with equal efficacy using dilute (5 wt. % of aqueous phase) hydrogen peroxide as a noncorrosive, environmentally benign oxidant (e.g., t(1/2) (HD) approximately 18 s, (2-chloroethyl phenyl sulfide, C(6)H(5)SCH(2)CH(2)Cl) approximately 15 s, (thiodiglycol, S(CH(2)CH(2)OH)(2)) approximately 19 s {20 degrees C}). Our observations demonstrate that by programming catalyst lipophilicity to colocalize catalyst and substrate, the inherent compartmentalization of the microemulsion can be exploited to achieve enhanced rates of reaction or to exert control over product selectivity. A combination of SANS, ESI-MS and fluorescence quenching measurements indicate that the enhanced catalytic activity is due to the locus of the catalyst and not a result of partial hydrolysis of the substrate.

Iron-carbon composites for the remediation of chlorinated hydrocarbons

NASA Astrophysics Data System (ADS)

Sunkara, Bhanu Kiran

This research is focused on engineering submicron spherical carbon particles as effective carriers/supports for nanoscale zerovalent iron (NZVI) particles to address the in situ remediation of soil and groundwater chlorinated contaminants. Chlorinated hydrocarbons such as trichloroethylene (TCE) and tetrachloroethylene (PCE) form a class of dense non-aqueous phase liquid (DNAPL) toxic contaminants in soil and groundwater. The in situ injection of NZVI particles to reduce DNAPLs is a potentially simple, cost-effective, and environmentally benign technology that has become a preferred method in the remediation of these compounds. However, unsupported NZVI particles exhibit ferromagnetism leading to particle aggregation and loss in mobility through the subsurface. This work demonstrates two approaches to prepare carbon supported NZVI (iron-carbon composites) particles. The objective is to establish these iron-carbon composites as extremely useful materials for the environmental remediation of chlorinated hydrocarbons and suitable materials for the in situ injection technology. This research also demonstrates that it is possible to vary the placement of iron nanoparticles either on the external surface or within the interior of carbon microspheres using a one-step aerosol-based process. The simple process of modifying iron placement has significant potential applications in heterogeneous catalysis as both the iron and carbon are widely used catalysts and catalyst supports. Furthermore, the aerosol-based process is applied to prepare new class of supported catalytic materials such as carbon-supported palladium nanoparticles for ex situ remediation of contaminated water. The iron-carbon composites developed in this research have multiple functionalities (a) they are reactive and function effectively in reductive dehalogenation (b) they are highly adsorptive thereby bringing the chlorinated compound to the proximity of the reactive sites and also serving as adsorption materials for decontamination (c) they are of the optimal size for transport through sediments (d) they have amphiphilic chemical functionalities that help stabilize them when they reach the DNAPL target zones. Finally, the iron-carbon composite microspheres prepared through aerosol-based process can used for in situ injection technology as the process is conductive to scale-up and the materials are environmentally benign.

Isoelectronic Manganese and Iron Hydrogenation/Dehydrogenation Catalysts: Similarities and Divergences.

PubMed

Gorgas, Nikolaus; Kirchner, Karl

2018-06-19

Sustainable processes that utilize nontoxic, readily available, and inexpensive starting materials for organic synthesis constitute a major objective in modern chemical research. In this context, it is highly important to perform reactions under catalytic conditions and to replace precious metal catalysts by earth-abundant nonprecious metal catalysts. In particular, iron and manganese are promising candidates, as these are among the most abundant metals in the earth's crust, are inexpensive, and exhibit a low environmental impact. As far as chemical processes are concerned, hydrogenations and acceptorless alcohol dehydrogenation (AAD), sometimes in conjunction with hydrogen autotransfer reactions, are becoming important areas of research. While the first is a very important synthetic process representing a highly atom-efficient and clean methodology, AAD is an oxidant-free, environmentally benign reaction where carbonyl compounds together with dihydrogen as a valuable product and/or reactant (autotransfer) and water are formed. Carbonyl compounds, typically generated in situ, can be converted into other useful organic materials such as amines, imines, or heterocycles. In 2016 several groups, including ours, discovered for the first time the potential of hydride biscarbonyl Mn(I) complexes bearing strongly bound PNP pincer ligands or related tridentate ligands as highly effective and versatile catalysts for hydrogenation, transfer hydrogenation, and dehydrogenation reactions. These complexes are isoelectronic analogues of the respective hydride monocarbonyl Fe(II) PNP compounds and display similar reactivities but also quite divergent behavior depending on the coligands. Moreover, manganese compounds show improved long-term stability and high robustness toward harsh reaction conditions. In light of these recent achievements, this Account contrasts Mn(I) and Fe(II) PNP pincer catalysts, highlighting specific features that are connected to particular structural and electronic properties. It also addresses opportunities and restrictions in their catalytic applications. Apart from classical hydrogenations, it also covers the most recent developments of these catalysts for AAD resulting in the synthesis of complex organic molecules such as heterocycles via multicomponent reactions. The ambivalent hydrogen-based redox chemistry provides access to a variety of synthetically valuable reductive and oxidative coupling reactions. Hence, these catalysts cover a broad scope of catalytic applications and exhibit activities and productivities that are becoming competitive with those of well-established precious metal catalysts. The knowledge about the nature and characteristics of active Mn(I)- and Fe(II)-based systems paves the way for conceptually and mechanistically well-founded research, which might lead to further developments and the discovery of novel catalysts extending the current scope and limitations of reactivity. It underlines that base metal catalysts are beginning to challenge precious metal catalysts and contributes to the further advancement of waste-free sustainable base metal catalysis.

Metal-polypyridyl catalysts for electro- and photochemical reduction of water to hydrogen.

PubMed

Zee, David Z; Chantarojsiri, Teera; Long, Jeffrey R; Chang, Christopher J

2015-07-21

Climate change, rising global energy demand, and energy security concerns motivate research into alternative, sustainable energy sources. In principle, solar energy can meet the world's energy needs, but the intermittent nature of solar illumination means that it is temporally and spatially separated from its consumption. Developing systems that promote solar-to-fuel conversion, such as via reduction of protons to hydrogen, could bridge this production-consumption gap, but this effort requires invention of catalysts that are cheap, robust, and efficient and that use earth-abundant elements. In this context, catalysts that utilize water as both an earth-abundant, environmentally benign substrate and a solvent for proton reduction are highly desirable. This Account summarizes our studies of molecular metal-polypyridyl catalysts for electrochemical and photochemical reduction of protons to hydrogen. Inspired by concept transfer from biological and materials catalysts, these scaffolds are remarkably resistant to decomposition in water, with fast and selective electrocatalytic and photocatalytic conversions that are sustainable for several days. Their modular nature offers a broad range of opportunities for tuning reactivity by molecular design, including altering ancillary ligand electronics, denticity, and/or incorporating redox-active elements. Our first-generation complex, [(PY4)Co(CH3CN)2](2+), catalyzes the reduction of protons from a strong organic acid to hydrogen in 50% water. Subsequent investigations with the pentapyridyl ligand PY5Me2 furnished molybdenum and cobalt complexes capable of catalyzing the reduction of water in fully aqueous electrolyte with 100% Faradaic efficiency. Of particular note, the complex [(PY5Me2)MoO](2+) possesses extremely high activity and durability in neutral water, with turnover frequencies at least 8500 mol of H2 per mole of catalyst per hour and turnover numbers over 600 000 mol of H2 per mole of catalyst over 3 days at an overpotential of 1.0 V, without apparent loss in activity. Replacing the oxo moiety with a disulfide affords [(PY5Me2)MoS2](2+), which bears a molecular MoS2 triangle that structurally and functionally mimics bulk molybdenum disulfide, improving the catalytic activity for water reduction. In water buffered to pH 3, catalysis by [(PY5Me2)MoS2](2+) onsets at 400 mV of overpotential, whereas [(PY5Me2)MoO](2+) requires an additional 300 mV of driving force to operate at the same current density. Metalation of the PY5Me2 ligand with an appropriate Co(ii) source also furnishes electrocatalysts that are active in water. Importantly, the onset of catalysis by the [(PY5Me2)Co(H2O)](2+) series is anodically shifted by introducing electron-withdrawing functional groups on the ligand. With the [(bpy2PYMe)Co(CF3SO3)](1+) system, we showed that introducing a redox-active moiety can facilitate the electro- and photochemical reduction of protons from weak acids such as acetic acid or water. Using a high-throughput photochemical reactor, we examined the structure-reactivity relationship of a series of cobalt(ii) complexes. Taken together, these findings set the stage for the broader application of polypyridyl systems to catalysis under environmentally benign aqueous conditions.

Highly-basic large-pore zeolite catalysts for NOx reduction at low temperatures

DOEpatents

Penetrante, Bernardino M.; Brusasco, Raymond M.; Merritt, Bernard T.; Vogtlin, George E.

2004-02-03

A high-surface-area (greater than 600 m2/g), large-pore (pore size diameter greater than 6.5 angstroms), basic zeolite having a structure such as an alkali metal cation-exchanged Y-zeolite is employed to convert NO.sub.x contained in an oxygen-rich engine exhaust to N.sub.2 and O.sub.2. Preferably, the invention relates to a two-stage method and apparatus for NO.sub.x reduction in an oxygen-rich engine exhaust such as diesel engine exhaust that includes a plasma oxidative stage and a selective reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and added hydrocarbons. The second stage employs a lean-NO.sub.x catalyst including the basic zeolite at relatively low temperatures to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O.

Sustainable Approach to Nanomaterials and Nano-Catalysts

EPA Science Inventory

Our recent activity on sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions is summarized. The synthesis of heterocyclic compounds, coupling reactions, and a...

Greener Syntheses and Chemical Transformations Using SustainableAlternative Methods and Nano-Catalysts

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, namely greener reaction medium in aqueous or solventfree conditions and using alternative activation via microwave or photocatalytic activation. Eco-friendly synthesis of nanoma...

Mechanochemical Nitration of Aromatic Compounds

NASA Astrophysics Data System (ADS)

Lagoviyer, Oleg S.; Krishtopa, Larisa; Schoenitz, Mirko; Trivedi, Nirupam J.; Dreizin, Edward L.

2018-04-01

Nitration of organic compounds is necessary to produce many energetic materials, such as TNT and nitrocellulose. The conventional nitration process uses a mixture of concentrated sulfuric and nitric acids as nitrating agents and multiple solvents. The chemicals are corrosive and require special handling and disposal procedures. In this study, aromatic nitration has been achieved using solvent-free mechanochemical processing of environmentally benign precursors. Mononitrotoluene was synthesized by milling toluene with sodium nitrate and molybdenum trioxide as a Lewis acid catalyst. Several parameters affecting the desired product yield were identified and varied. A number of byproducts, i.e., dimers of toluene were also produced, but the selectivity was observed to increase with increasing mononitrotoluene yield. Both absolute mononitrotoluene yields and selectivity of its production increased with the increase in the energy transferred to the material from the milling tools.

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

PubMed Central

2010-01-01

Summary The development of efficient Friedel–Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel–Crafts conditions as benzyl-, propargyl- and allyl alcohols, or styrenes, can be used instead of toxic benzyl halides. Additionally, only low catalyst loadings are needed to provide a wide range of products. Following a short introduction about the origin and classical definition of the Friedel–Crafts reaction, the review will describe the different environmentally benign substrates which can be applied today as an approach towards greener processes. Additionally, the first diastereoselective and enantioselective Friedel–Crafts-type alkylations will be highlighted. PMID:20485588

Laccase-catalyzed α-arylation of benzoylacetonitrile with substituted hydroquinones

DOE PAGES

Cannatelli, Mark D.; Ragauskas, Arthur J.

2014-09-03

This article investigates a green method for α-arylation of a primary nitrile. Compounds possessing a benzylic nitrile have shown to exhibit biological activity. Laccases (benzenediol:oxygen oxidoreductase EC 1.10.3.2) were used as the catalysts to perform the cross-coupling reaction between benzoylacetonitrile and substituted hydroquinones. The corresponding 2-substituted 3-oxo-3-phenylpropanenitriles where synthesized in moderate to excellent yields in pH 7.0 buffered water under mild conditions. The substituent on the hydroquinone had a significant impact on product yields and regioselectivity of reaction. The use of laccases, which require O 2 as their only co-substrate and produce H 2O as their only by-product, to performmore » this transformation is an environmentally benign method for α-arylation of primary nitriles.« less

NAP enzyme recruitment in simultaneous bioremediation and nanoparticles synthesis.

PubMed

Eltarahony, Marwa; Zaki, Sahar; Kheiralla, Zeinab; Abd-El-Haleem, Desouky

2018-06-01

The periplasmic nitrate reductase enzyme (NAP) has become attractive catalyst, whose exploitation has emerged as one of the indispensable strategies toward environmentally benign applications. To achieve them efficiently and overcome the sensitivity of NAP in harsh environmental circumstances, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was studied. NAP catalyzed NO 3 - reduction at V max of 0.811 μM/min and K m of 14.02 mM. Concurrently, the immobilized MMT cells completely removed NO 3 - upon 192 h with AgNPs synthesis ranging from 23.26 to 58.14 nm as indicated by SEM. Wherase, immobilized NAP exhibited lower efficiency with 28.6% of NO 3 - elimination within 288 h and large aggregated AgNPs ranging from 94.44 nm to 172.22 nm. To the best of author knowledge, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was not studied before.

Sustainable 'Greener' Methods for Chemical Transformations and Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 Synthesis of heterocyclic compounds, coupling reactions, and name reac...

Synthesis Under 'Greener' Conditions: Role of Sustainable Nano-Catalysts

EPA Science Inventory

The presentation summarizes our recent activity in chemical synthesis involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a varie...

Greener Synthesis and Chemical transformations Using Sustainable Alternative Methods and Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, namely greener reaction medium in aqueous or solventfree conditions and using alternative activation via microwave or photocatalytic activation. Eco-friendly synthesis of nanoma...

C3N4-H5PMo10V2O40: a dual-catalysis system for reductant-free aerobic oxidation of benzene to phenol

NASA Astrophysics Data System (ADS)

Long, Zhouyang; Zhou, Yu; Chen, Guojian; Ge, Weilin; Wang, Jun

2014-01-01

Hydroxylation of benzene is a widely studied atom economical and environmental benign reaction for producing phenol, aiming to replace the existing three-step cumene process. Aerobic oxidation of benzene with O2 is an ideal and dream process, but benzene and O2 are so inert that current systems either require expensive noble metal catalysts or wasteful sacrificial reducing agents; otherwise, phenol yields are extremely low. Here we report a dual-catalysis non-noble metal system by simultaneously using graphitic carbon nitride (C3N4) and Keggin-type polyoxometalate H5PMo10V2O40 (PMoV2) as catalysts, showing an exceptional activity for reductant-free aerobic oxidation of benzene to phenol. The dual-catalysis mechanism results in an unusual route to create phenol, in which benzene is activated on the melem unit of C3N4 and O2 by the V-O-V structure of PMoV2. This system is simple, highly efficient and thus may lead the one-step production of phenol from benzene to a more practical pathway.

C3N4-H5PMo10V2O40: a dual-catalysis system for reductant-free aerobic oxidation of benzene to phenol

PubMed Central

Long, Zhouyang; Zhou, Yu; Chen, Guojian; Ge, Weilin; Wang, Jun

2014-01-01

Hydroxylation of benzene is a widely studied atom economical and environmental benign reaction for producing phenol, aiming to replace the existing three-step cumene process. Aerobic oxidation of benzene with O2 is an ideal and dream process, but benzene and O2 are so inert that current systems either require expensive noble metal catalysts or wasteful sacrificial reducing agents; otherwise, phenol yields are extremely low. Here we report a dual-catalysis non-noble metal system by simultaneously using graphitic carbon nitride (C3N4) and Keggin-type polyoxometalate H5PMo10V2O40 (PMoV2) as catalysts, showing an exceptional activity for reductant-free aerobic oxidation of benzene to phenol. The dual-catalysis mechanism results in an unusual route to create phenol, in which benzene is activated on the melem unit of C3N4 and O2 by the V-O-V structure of PMoV2. This system is simple, highly efficient and thus may lead the one-step production of phenol from benzene to a more practical pathway. PMID:24413448

Single-Walled Carbon Nanohorns for Energy Applications

PubMed Central

Zhang, Zhichao; Han, Shuang; Wang, Chao; Li, Jianping; Xu, Guobao

2015-01-01

With the growth of the global economy and population, the demand for energy is increasing sharply. The development of environmentally a benign and reliable energy supply is very important and urgent. Single-walled carbon nanohorns (SWCNHs), which have a horn-shaped tip at the top of single-walled nanotube, have emerged as exceptionally promising nanomaterials due to their unique physical and chemical properties since 1999. The high purity and thermal stability, combined with microporosity and mesoporosity, high surface area, internal pore accessibility, and multiform functionalization make SWCNHs promising candidates in many applications, such as environment restoration, gas storage, catalyst support or catalyst, electrochemical biosensors, drug carrier systems, magnetic resonance analysis and so on. The aim of this review is to provide a comprehensive overview of SWCNHs in energy applications, including energy conversion and storage. The commonly adopted method to access SWCNHs, their structural modifications, and their basic properties are included, and the emphasis is on their application in different devices such as fuel cells, dye-sensitized solar cells, supercapacitors, Li-ion batteries, Li-S batteries, hydrogen storage, biofuel cells and so forth. Finally, a perspective on SWCNHs’ application in energy is presented. PMID:28347092

Efficient Access to Imidazo[1,2- a]pyridines/pyrazines/pyrimidines via Catalyst-Free Annulation Reaction under Microwave Irradiation in Green Solvent.

PubMed

Rao, R Nishanth; Mm, Balamurali; Maiti, Barnali; Thakuria, Ranjit; Chanda, Kaushik

2018-03-12

An expeditious catalyst-free heteroannulation reaction for imidazo[1,2- a]pyridines/pyrimidines/pyrazines was developed in green solvent under microwave irradiation. Using H 2 O-IPA as the reaction medium, various substituted 2-aminopyridines/pyrazines/pyrimidines underwent annulation reaction with α-bromoketones under microwave irradiation to provide the corresponding imidazo[1,2- a]pyridines/pyrimidines/pyrazines in excellent yields. The synthetic methodology appears to be very simple and superior to the already reported procedures with the high abundance of commercial reagents and great ability in expanding the molecular diversity. The present synthetic sequence is visualized as an environmentally benign process which allows the introduction of three points of structural diversity to expand chemical space with excellent purity and yields. The anti-inflammatory and antimicrobial activities of the derivatives were evaluated. Screening results uncovered three derivatives with strong inhibition of albumin denaturation and two derivatives were active on Proteus and Klebsiella bacteria. These positive bioassay results implied that the library of potential anti-inflammatory agents could be rapidly prepared in an ecofriendly manner, and provided new insights into drug discovery for medicinal chemists.

Greener Approach to Organics and Nanomaterials and Sustainable Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our green chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a variety ...

Greener Synthesis of Organics and Nanomaterials: Sustainable Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our recent activity in chemical synthesis involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a varie...

Recent progress in asymmetric bifunctional catalysis using multimetallic systems.

PubMed

Shibasaki, Masakatsu; Kanai, Motomu; Matsunaga, Shigeki; Kumagai, Naoya

2009-08-18

The concept of bifunctional catalysis, wherein both partners of a bimolecular reaction are simultaneously activated, is very powerful for designing efficient asymmetric catalysts. Catalytic asymmetric processes are indispensable for producing enantiomerically enriched compounds in modern organic synthesis, providing more economical and environmentally benign results than methods requiring stoichiometric amounts of chiral reagents. Extensive efforts in this field have produced many asymmetric catalysts, and now a number of reactions can be rendered asymmetric. We have focused on the development of asymmetric catalysts that exhibit high activity, selectivity, and broad substrate generality under mild reaction conditions. Asymmetric catalysts based on the concept of bifunctional catalysis have emerged as a particularly effective class, enabling simultaneous activation of multiple reaction components. Compared with conventional catalysts, bifunctional catalysts generally exhibit enhanced catalytic activity and higher levels of stereodifferentiation under milder reaction conditions, attracting much attention as next-generation catalysts for prospective practical applications. In this Account, we describe recent advances in enantioselective catalysis with bifunctional catalysts. Since our identification of heterobimetallic rare earth-alkali metal-BINOL (REMB) complexes, we have developed various types of bifunctional multimetallic catalysts. The REMB catalytic system is effective for catalytic asymmetric Corey-Chaykovsky epoxidation and cyclopropanation. A dinucleating Schiff base has emerged as a suitable multidentate ligand for bimetallic catalysts, promoting catalytic syn-selective nitro-Mannich, anti-selective nitroaldol, and Mannich-type reactions. The sugar-based ligand GluCAPO provides a suitable platform for polymetallic catalysts; structural elucidation revealed that their higher order polymetallic structures are a determining factor for their function in the catalytic asymmetric Strecker reaction. Rational design identified a related ligand, FujiCAPO, which exhibits superior performance in catalytic asymmetric conjugate addition of cyanide to enones and a catalytic asymmetric Diels-Alder-type reaction. The combination of an amide-based ligand with a rare earth metal constitutes a unique catalytic system: the ligand-metal association is in equilibrium because of structural flexibility. These catalytic systems are effective for asymmetric amination of highly coordinative substrate as well as for Mannich-type reaction of alpha-cyanoketones, in which hydrogen bonding cooperatively contributes to substrate activation and stereodifferentiation. Most of the reactions described here generate stereogenic tetrasubstituted carbons or quaternary carbons, noteworthy accomplishments even with modern synthetic methods. Several reactions have been incorporated into the asymmetric synthesis of therapeutics (or their candidate molecules) such as Tamiflu, AS-3201 (ranirestat), GRL-06579A, and ritodrine, illustrating the usefulness of bifunctional asymmetric catalysis.

Greener Syntheses and Chemical Transformations: Sustainable Alternative Methods and Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a var...

Green Approach to Nanomaterials: Sustainable Utility of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our synthetic activity for the preparation of nanoparticles involving benign alternatives which reduces or eliminates the use and generation of hazardous substances. Vitamins B1, B2, C, and tea and wine polyphenols which function both as reducing and c...

Green Synthesis of Organics and Nanomaterials and Sustainable Applications of Nano-Catalysts- HESTEC

EPA Science Inventory

The presentation summarizes our green chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a variety o...

Green Synthesis of Organics and Nanomaterials and Sustainable Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our green chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a variety o...

Greener Syntheses and Chemical Transformations: Sustainable Alternative Methods and Applications of Nano-Catalysts. (Florence, Italy)

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions. The synthesis of heterocyclic compounds, coupling reactions, and a vari...

Eco-friendly Synthesis of Organics and Nanomaterials: Sustainable Applications of Nano-Catalysts

EPA Science Inventory

The presentation summarizes our recent activity in chemical synthesis involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a varie...

Green synthesis of Pd nanoparticles at Apricot kernel shell substrate using Salvia hydrangea extract: Catalytic activity for reduction of organic dyes.

PubMed

Khodadadi, Bahar; Bordbar, Maryam; Nasrollahzadeh, Mahmoud

2017-03-15

For the first time the extract of the plant of Salvia hydrangea was used to green synthesis of Pd nanoparticles (NPs) supported on Apricot kernel shell as an environmentally benign support. The Pd NPs/Apricot kernel shell as an effective catalyst was prepared through reduction of Pd 2+ ions using Salvia hydrangea extract as the reducing and capping agent and Pd NPs immobilization on Apricot kernel shell surface in the absence of any stabilizer or surfactant. According to FT-IR analysis, the hydroxyl groups of phenolics in Salvia hydrangea extract as bioreductant agents are directly responsible for the reduction of Pd 2+ ions and formation of Pd NPs. The as-prepared catalyst was characterized by Fourier transform infrared (FT-IR) and UV-Vis spectroscopy, field emission scanning electron microscopy (FESEM) equipped with an energy dispersive X-ray spectroscopy (EDS), Elemental mapping, X-ray diffraction analysis (XRD) and transmittance electron microscopy (TEM). The synthesized catalyst was used in the reduction of 4-nitrophenol (4-NP), Methyl Orange (MO), Methylene Blue (MB), Rhodamine B (RhB), and Congo Red (CR) at room temperature. The Pd NPs/Apricot kernel shell showed excellent catalytic activity in the reduction of these organic dyes. In addition, it was found that Pd NPs/Apricot kernel shell can be recovered and reused several times without significant loss of catalytic activity. Copyright © 2016 Elsevier Inc. All rights reserved.

Sustainable Applications of Nano-Catalysts and Alternative Methods in the Greener Synthesis and Transformations of Chemical

EPA Science Inventory

The presentation summarizes our sustainable chemical synthesis activity involving benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions.1 The synthesis of heterocyclic compounds, coupling reactions, and a var...

ENVIRONMENTAL TECHNOLOGY VERIFICATION, TEST REPORT OF MOBILE SOURCE EMISSIONS CONTROL DEVICES/CLEAN DIESEL TECHNOLOGIES FUEL BORNE CATALYST WITH CLEANAIR SYSTEM'S DIESEL OXIDATION CATALYST

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the Fuel-Borne Catalyst with CleanAir System's Diesel Oxidation Catalyst manufactured by Clean Diesel Technologies, Inc. The technology is a fuel-borne catalyst used in ultra low sulfur d...

Hierarchical porous silver metal using Pluronic F-127 and graphene oxide as reinforcing agents for the reduction of o-nitroaniline to 1, 2-benzenediamine

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

Bano, Mustri; Ahirwar, Devendra; Thomas, Molly

An elegant method is used to prepare silver monoliths with Pluronic F-127(F-127) as sacrificial template by modified sol-gel method. Si nanoparticles (SiNPs) and graphene oxide (GO) are added in situ to Ag/F-127 hydrogel for the reduction of ο-nitroaniline (ο-NA) to 1, 2-benzenediamine. Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), Raman Spectroscopy, Powder X-Ray Diffraction (PXRD) analysis and Brunauer-Emmett-Teller (BET) Nitrogen adsorption techniques were used for characterization of monoliths. An epoch-making catalytic activity of Ag/F-127/GO monoliths is observed in the reduction of ο-NA to 1, 2-benzenediamine in presence of NaBH{sub 4} inmore » aqueous media. The catalyst Ag/F-127/GO took only 2 min which is the minimum time reported so far with significant rate constant claimed itself a leading catalyst for the reduction of ο-NA to 1,2-benzenediamine. Pseudo first order rate constant (k) and Turn over frequency (TOF) values are 0.231 min{sup −1} and 30.053×10{sup 19} molecules min{sup −1} respectively suggest that the catalyst has industrial importance. Recyclability and stability of Ag/F-127/GO catalyst are studied successfully up to 10 cycles. Energy of activation (E{sub a}), and thermodynamic parameters viz. activation enthalpy (ΔH{sup ≠}), activation Gibbs free energy (ΔG{sup ≠}), and entropy of activation (ΔS{sup ≠}) were also ascertained. Catalytic activities of Ag/F-127, Ag/F-127/Dextran, Ag/F-127/Trimethylbenzene (TMB), Ag/F-127/SiNPs, and Ag/F-127/Si/GO monoliths were also studied. - Graphical abstract: Significant catalytic activities of silver monoliths against the reduction of ο-NA to 1,2 benzenediamine. - Highlights: • A new catalyst synthesized Ag/F-127/GO for the reduction of ο- NA to 1, 2- benzenediamine took only 2 min. • Turn over frequency of as synthesized catalyst was 30.053×10{sup 19} molecules min{sup −1} claimed itself a leading catalyst. • Recyclability of the catalyst was up to 10 cycles. • The synthesis is non toxic, economically viable and environmentally benign.« less

Photocatalytic acceptorless alkane dehydrogenation: scope, mechanism, and conquering deactivation with carbon dioxide.

PubMed

Chowdhury, Abhishek Dutta; Julis, Jennifer; Grabow, Kathleen; Hannebauer, Bernd; Bentrup, Ursula; Adam, Martin; Franke, Robert; Jackstell, Ralf; Beller, Matthias

2015-01-01

Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetically recyclable magnetite-ceria (Nanocat-Fe-Ce) nanocatalysts - applications in multicomponent reactions under benign conditions

EPA Science Inventory

A novel magnetite nanoparticle-supported ceria catalyst (Nanocat-Fe-Ce) has been successfully prepared by simple impregnation method and was well characterized by XRD, SIMS, FEG-SEM-EDS, and TEM. The exact nature of Nanocat-Fe-Ce was confirmed by X-ray photoelectron spectroscopy ...

Gold(III)-Catalyzed Hydration of Phenylacetylene

ERIC Educational Resources Information Center

Leslie, J. Michelle; Tzeel, Benjamin A.

2016-01-01

A guided inquiry-based experiment exploring the regioselectivity of the hydration of phenylacetylene is described. The experiment uses an acidic gold(III) catalyst in a benign methanol/water solvent system to introduce students to alkyne chemistry and key principles of green chemistry. The experiment can be easily completed in approximately 2 h,…

NOVEL RHODIUM (I) CATALYSTS FOR ECOLOGICALLY BENIGN HOMOGENEOUS CATALYSIS IN SUPERCRITICAL CARBON DIOXIDE. (R826694C640)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Copper-catalyzed Green and Expeditious N-Arylation of Sulfoximines using Diaryliodonium Salts

EPA Science Inventory

An ultrasound-accelerated green route for an expeditious N-arylation of NH-sulfoximines is described that involves the use of benign diaryliodonium salts in aqueous polyethylene glycol-400 and copper(I) bromide as catalyst at room temperature. The high yields of the products and...

Aerosol processing: a wind of innovation in the field of advanced heterogeneous catalysts.

PubMed

Debecker, Damien P; Le Bras, Solène; Boissière, Cédric; Chaumonnot, Alexandra; Sanchez, Clément

2018-06-05

Aerosol processing is long known and implemented industrially to obtain various types of divided materials and nanomaterials. The atomisation of a liquid solution or suspension produces a mist of aerosol droplets which can then be transformed via a diversity of processes including spray-drying, spray pyrolysis, flame spray pyrolysis, thermal decomposition, micronisation, gas atomisation, etc. The attractive technical features of these aerosol processes make them highly interesting for the continuous, large scale, and tailored production of heterogeneous catalysts. Indeed, during aerosol processing, each liquid droplet undergoes well-controlled physical and chemical transformations, allowing for example to dry and aggregate pre-existing solid particles or to synthesise new micro- or nanoparticles from mixtures of molecular or colloidal precursors. In the last two decades, more advanced reactive aerosol processes have emerged as innovative means to synthesise tailored-made nanomaterials with tunable surface properties, textures, compositions, etc. In particular, the "aerosol-assisted sol-gel" process (AASG) has demonstrated tremendous potential for the preparation of high-performance heterogeneous catalysts. The method is mainly based on the low-cost, scalable, and environmentally benign sol-gel chemistry process, often coupled with the evaporation-induced self-assembly (EISA) concept. It allows producing micronic or submicronic, inorganic or hybrid organic-inorganic particles bearing tuneable and calibrated porous structures at different scales. In addition, pre-formed nanoparticles can be easily incorporated or formed in a "one-pot" bottom-up approach within the porous inorganic or hybrid spheres produced by such spray drying method. Thus, multifunctional catalysts with tailored catalytic activities can be prepared in a relatively simple way. This account is an overview of aerosol processed heterogeneous catalysts which demonstrated interesting performance in various relevant chemical reactions like isomerisation, hydrogenation, olefin metathesis, pollutant total oxidation, selective oxidation, CO2 methanation, etc. A short survey of patents and industrial applications is also presented. Our objective is to demonstrate the tremendous possibilities offered by the coupling between bottom up synthesis routes and these aerosol processing technologies which will most probably represent a major route of innovation in the mushrooming field of catalyst preparation research.

Oxidation of primary amines to oximes with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO3/Al2O3 as catalysts.

PubMed

Suzuki, Ken; Watanabe, Tomonari; Murahashi, Shun-Ichi

2013-03-15

The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O2/N2 = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO3/Al2O3 gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6.

Large-scale additive manufacturing with bioinspired cellulosic materials.

PubMed

Sanandiya, Naresh D; Vijay, Yadunund; Dimopoulou, Marina; Dritsas, Stylianos; Fernandez, Javier G

2018-06-05

Cellulose is the most abundant and broadly distributed organic compound and industrial by-product on Earth. However, despite decades of extensive research, the bottom-up use of cellulose to fabricate 3D objects is still plagued with problems that restrict its practical applications: derivatives with vast polluting effects, use in combination with plastics, lack of scalability and high production cost. Here we demonstrate the general use of cellulose to manufacture large 3D objects. Our approach diverges from the common association of cellulose with green plants and it is inspired by the wall of the fungus-like oomycetes, which is reproduced introducing small amounts of chitin between cellulose fibers. The resulting fungal-like adhesive material(s) (FLAM) are strong, lightweight and inexpensive, and can be molded or processed using woodworking techniques. We believe this first large-scale additive manufacture with ubiquitous biological polymers will be the catalyst for the transition to environmentally benign and circular manufacturing models.

Green synthesis, characterization and catalytic activity of the Pd/TiO2 nanoparticles for the ligand-free Suzuki-Miyaura coupling reaction.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad

2016-03-01

A green synthesis process was developed for production of the Pd/TiO2 nanoparticles (NPs) without using toxic, hazardous and dangerous materials. Myrtus communis L. leaf extract serves as a mild, renewable and non-toxic reducing agent. The advantages of this biosynthesis method include use of cheap, clean, nontoxic and environmentally benign precursors and simple procedures without time-consuming polymerization and problems with treatment of a highly viscous polymeric resin. More importantly, the synthesized Pd/TiO2 NPs presented excellent catalytic activity for ligand-free Suzuki-Miyaura coupling which could be easily separated from the reaction mixture and reused many times with no loss of activity. Therefore, these properties indicate demonstrative benefits of the catalyst. The Pd/TiO2 NPs was characterized by FESEM, TEM, FT-IR, UV-vis spectroscopy and EDS. Copyright © 2015 Elsevier Inc. All rights reserved.

Manganese complex-catalyzed oxidation and oxidative kinetic resolution of secondary alcohols by hydrogen peroxide.

PubMed

Miao, Chengxia; Li, Xiao-Xi; Lee, Yong-Min; Xia, Chungu; Wang, Yong; Nam, Wonwoo; Sun, Wei

2017-11-01

The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn-oxo species. Density functional theory calculations revealed the difference in reaction energy barriers for H-atom abstraction from the α-CH bonds of R - and S -enantiomers by a chiral high-valent manganese-oxo complex, supporting the experimental result from the OKR of secondary alcohols.

The Role of Ultrasound on Advanced Oxidation Processes.

PubMed

Babu, Sundaram Ganesh; Ashokkumar, Muthupandian; Neppolian, Bernaurdshaw

2016-10-01

This chapter describes the use of ultrasound in remediation of wastewater contaminated with organic pollutants in the absence and presence of other advanced oxidation processes (AOPs) such as sonolysis, sono-ozone process, sonophotocatalysis, sonoFenton systems and sonophoto-Fenton methods in detail. All these methods are explained with the suitable literature illustrations. In most of the cases, hybrid AOPs (combination of ultrasound with one or more AOPs) resulted in superior efficacy to that of individual AOP. The advantageous effects such as additive and synergistic effects obtained by operating the hybrid AOPs are highlighted with appropriate examples. It is worth to mention here that the utilization of ultrasound is not only restricted in preparation of modern active catalysts but also extensively used for the wastewater treatment. Interestingly, ultrasound coupled AOPs are operationally simple, efficient, and environmentally benign, and can be readily applied for large scale industrial processes which make them economically viable.

ENVIRONMENTALLY-BENIGN MULTIPHASE CATALYSIS. (R826034)

EPA Science Inventory

Environmental concerns stemming from the use of conventional solvents and from hazardous waste generation have propelled research efforts aimed at developing benign chemical processing techniques that either eliminate or significantly mitigate pollution at the source. This pap...

Synthesis and Characterization of Environmentally Benign Nanoparticles

EPA Science Inventory

There has been a growing interest in replacing current non-biodegradable and toxic nanosystems with environmentally benign biopolymer based ones to minimize post-utilization hazards due to uncontrolled accumulation of nanoparticles in the environment. Lignin based nanoparticles (...

Can laboratory and pilot recycling trials predict adhesive removal in commercial recycling systems? : results from the USPS environmentally benign stamp project

Treesearch

Carl Houtman; Daniel Seiter; Nancy Ross Sutherland; Donald Donermeyer

2002-01-01

The ultimate goal of the US Postal Service (USPS) Environmentally Benign Stamp Program is to develop stamp laminates, i.e., face paper, adhesive and siliconized liner, that do not cause difficulties in recycling mills. The criterion for success, and the USPS definition of benignity, is the avoidance of process and product quality hardships when such PSA laminates are...

A heuristic approach using multiple criteria for environmentally benign 3PLs selection

NASA Astrophysics Data System (ADS)

Kongar, Elif

2005-11-01

Maintaining competitiveness in an environment where price and quality differences between competing products are disappearing depends on the company's ability to reduce costs and supply time. Timely responses to rapidly changing market conditions require an efficient Supply Chain Management (SCM). Outsourcing logistics to third-party logistics service providers (3PLs) is one commonly used way of increasing the efficiency of logistics operations, while creating a more "core competency focused" business environment. However, this alone may not be sufficient. Due to recent environmental regulations and growing public awareness regarding environmental issues, 3PLs need to be not only efficient but also environmentally benign to maintain companies' competitiveness. Even though an efficient and environmentally benign combination of 3PLs can theoretically be obtained using exhaustive search algorithms, heuristics approaches to the selection process may be superior in terms of the computational complexity. In this paper, a hybrid approach that combines a multiple criteria Genetic Algorithm (GA) with Linear Physical Weighting Algorithm (LPPW) to be used in efficient and environmentally benign 3PLs is proposed. A numerical example is also provided to illustrate the method and the analyses.

THE DESIGN OF TECHNOLOGICALLY EFFECTIVE AND ENVIRONMENTALLY BENIGN SOLVENT SUBSTITUTES

EPA Science Inventory

There is presently considerable interest in finding environmentally benign replacement solvents that can perform in many different applications as solvents normally do. This requires solvents with desirable properties, e.g., ability to dissolve certain compounds, and without oth...

A Membrane-Free Neutral pH Formate Fuel Cell Enabled by a Selective Nickel Sulfide Oxygen Reduction Catalyst.

PubMed

Yan, Bing; Concannon, Nolan M; Milshtein, Jarrod D; Brushett, Fikile R; Surendranath, Yogesh

2017-06-19

Polymer electrolyte membranes employed in contemporary fuel cells severely limit device design and restrict catalyst choice, but are essential for preventing short-circuiting reactions at unselective anode and cathode catalysts. Herein, we report that nickel sulfide Ni 3 S 2 is a highly selective catalyst for the oxygen reduction reaction in the presence of 1.0 m formate. We combine this selective cathode with a carbon-supported palladium (Pd/C) anode to establish a membrane-free, room-temperature formate fuel cell that operates under benign neutral pH conditions. Proof-of-concept cells display open circuit voltages of approximately 0.7 V and peak power values greater than 1 mW cm -2 , significantly outperforming the identical device employing an unselective platinum (Pt) cathode. The work establishes the power of selective catalysis to enable versatile membrane-free fuel cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iron Oxide-Supported Copper Oxide Nanoparticles (Nanocat-Fe-CuO): Magnetically Recyclable Catalysts for the Synthesis of Pyrazole Derivatives, 4-Methoxyaniline, and Ullmann-type Condensation Reactions

EPA Science Inventory

An efficient and benign protocol is reported for the synthesis of 4-methoxyaniline, medicinally important pyrazole derivatives, and Ullmann-type condensation reaction using magnetically separable and reusable magnetite-supported copper (nanocat-Fe-CuO) nanoparticles under mild co...

Oxidative Dehydrogenation on Nanocarbon: Insights into the Reaction Mechanism and Kinetics via in Situ Experimental Methods.

PubMed

Qi, Wei; Yan, Pengqiang; Su, Dang Sheng

2018-03-20

Sustainable and environmentally benign catalytic processes are vital for the future to supply the world population with clean energy and industrial products. The replacement of conventional metal or metal oxide catalysts with earth abundant and renewable nonmetallic materials has attracted considerable research interests in the field of catalysis and material science. The stable and efficient catalytic performance of nanocarbon materials was discovered at the end of last century, and these materials are considered as potential alternatives for conventional metal-based catalysts. With its rapid development in the past 20 years, the research field of carbon catalysis has been experiencing a smooth transition from the discovery of novel nanocarbon materials or related new reaction systems to the atomistic-level mechanistic understanding on the catalytic process and the subsequent rational design of the practical catalytic reaction systems. In this Account, we summarize the recent progress in the kinetic and mechanistic studies on nanocarbon catalyzed alkane oxidative dehydrogenation (ODH) reactions. The paper attempts to extract general concepts and basic regularities for carbon catalytic process directing us on the way for rational design of novel efficient metal-free catalysts. The nature of the active sites for ODH reactions has been revealed through microcalorimetric analysis, ambient pressure X-ray photoelectron spectroscopy (XPS) measurement, and in situ chemical titration strategies. The detailed kinetic analysis and in situ catalyst structure characterization suggests that carbon catalyzed ODH reactions involve the redox cycles of the ketonic carbonyl-hydroxyl pairs, and the key physicochemical parameters (activation energy, reaction order, and rate/equilibrium constants, etc.) of the carbon catalytic systems are proposed and compared with conventional transition metal oxide catalysts. The proposal of the intrinsic catalytic activity (TOF) provides the possibility for the fair comparisons of different nanocarbon catalysts and the consequent structure-function relation regularity. Surface modification and heteroatom doping are proved as the most effective strategies to adjust the catalytic property (activity and product selectivity etc.) of the nanocarbon catalysts. Nanocarbon is actually a proper candidate platform helping us to understand the classical catalytic reaction mechanism better, since there is no lattice oxygen and all the catalytic process happens on nanocarbon surface. This Account also exhibits the importance of the in situ structural characterizations for heterogeneous nanocarbon catalysis. The research strategy and methods proposed for carbon catalysts may also shed light on other complicated catalytic systems or fields concerning the applications of nonmetallic materials, such as energy storage and environment protection etc.

Performance and life cycle environmental benefits of recycling spent ion exchange brines by catalytic treatment of nitrate.

PubMed

Choe, Jong Kwon; Bergquist, Allison M; Jeong, Sangjo; Guest, Jeremy S; Werth, Charles J; Strathmann, Timothy J

2015-09-01

Salt used to make brines for regeneration of ion exchange (IX) resins is the dominant economic and environmental liability of IX treatment systems for nitrate-contaminated drinking water sources. To reduce salt usage, the applicability and environmental benefits of using a catalytic reduction technology to treat nitrate in spent IX brines and enable their reuse for IX resin regeneration were evaluated. Hybrid IX/catalyst systems were designed and life cycle assessment of process consumables are used to set performance targets for the catalyst reactor. Nitrate reduction was measured in a typical spent brine (i.e., 5000 mg/L NO3(-) and 70,000 mg/L NaCl) using bimetallic Pd-In hydrogenation catalysts with variable Pd (0.2-2.5 wt%) and In (0.0125-0.25 wt%) loadings on pelletized activated carbon support (Pd-In/C). The highest activity of 50 mgNO3(-)/(min - g(Pd)) was obtained with a 0.5 wt%Pd-0.1 wt%In/C catalyst. Catalyst longevity was demonstrated by observing no decrease in catalyst activity over more than 60 days in a packed-bed reactor. Based on catalyst activity measured in batch and packed-bed reactors, environmental impacts of hybrid IX/catalyst systems were evaluated for both sequencing-batch and continuous-flow packed-bed reactor designs and environmental impacts of the sequencing-batch hybrid system were found to be 38-81% of those of conventional IX. Major environmental impact contributors other than salt consumption include Pd metal, hydrogen (electron donor), and carbon dioxide (pH buffer). Sensitivity of environmental impacts of the sequencing-batch hybrid reactor system to sulfate and bicarbonate anions indicate the hybrid system is more sustainable than conventional IX when influent water contains <80 mg/L sulfate (at any bicarbonate level up to 100 mg/L) or <20 mg/L bicarbonate (at any sulfate level up to 100 mg/L) assuming 15 brine reuse cycles. The study showed that hybrid IX/catalyst reactor systems have potential to reduce resource consumption and improve environmental impacts associated with treating nitrate-contaminated water sources. Copyright © 2015 Elsevier Ltd. All rights reserved.

ENVIRONMENTAL TECHNOLOGY VERIFICATION, TEST REPORT OF MOBILE SOURCE EMISSIONS CONTROL DEVICES: CLEAN DIESEL TECHNOLOGIES FUEL-BORNE CATALYST WITH MITSUI/PUREARTH CATALYZED WIRE MESH FILTER

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the Fuel-Borne Catalyst with Mitsui/PUREarth Catalyzed Wire Mesh Filter manufactured by Clean Diesel Technologies, Inc. The technology is a platinum/cerium fuel-borne catalyst in commerci...

Interconversion of CO2 and formic acid by bio-inspired Ir complexes with pendent bases.

PubMed

Fujita, Etsuko; Muckerman, James T; Himeda, Yuichiro

2013-01-01

Recent investigations of the interconversion of CO2 and formic acid using Ru, Ir and Fe complexes are summarized in this review. During the past several years, both the reaction rates and catalyst stabilities have been significantly improved. Remarkably, the interconversion (i.e., reversibility) has also been achieved under mild conditions in environmentally benign water solvent by slightly changing the pH of the aqueous solution. Only a few catalysts seem to reflect a bio-inspired design such as the use of proton responsive ligands, ligands with pendent bases or acids for a second-coordination-sphere interaction, electroresponsive ligands, and/or ligands having a hydrogen bonding function with a solvent molecule or an added reagent. The most successful of these is an iridium dinuclear complex catalyst that at least has the first three of these characteristics associated with its bridging ligand. By utilizing an acid/base equilibrium for proton removal, the ligand becomes a strong electron donor, resulting in Ir(I) character with a vacant coordination site at each metal center in slightly basic solution. Complemented by DFT calculations, kinetic studies of the rates of formate production using a related family of Ir complexes with and without such functions on the ligand reveal that the rate-determining step for the CO2 hydrogenation is likely to be H2 addition through heterolytic cleavage involving a "proton relay" through the pendent base. The dehydrogenation of formic acid, owing to the proton responsive ligands changing character under slightly acidic pH conditions, is likely to occur by a mechanism with a different rate-determining step. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. Copyright © 2012 Elsevier B.V. All rights reserved.

Situ treatment of contaminated groundwater

DOEpatents

McNab, Jr., Walt W.; Ruiz, Roberto; Pico, Tristan M.

2001-01-01

A system for treating dissolved halogenated organic compounds in groundwater that relies upon electrolytically-generated hydrogen to chemically reduce the halogenated compounds in the presence of a suitable catalyst. A direct current is placed across at least a pair, or an array, of electrodes which are housed within groundwater wells so that hydrogen is generated at the cathode and oxygen at the anode. A pump is located within the well housing in which the cathode(s) is(are) located and draws in groundwater where it is hydrogenated via electrolysis, passes through a well-bore treatment unit, and then transported to the anode well(s) for reinjection into the ground. The well-bore treatment involves a permeable cylinder located in the well bore and containing a packed bed of catalyst material that facilitates the reductive dehalogenation of the halogenated organic compounds by hydrogen into environmentally benign species such as ethane and methane. Also, electro-osmatic transport of contaminants toward the cathode also contributes to contaminant mass removal. The only above ground equipment required are the transfer pipes and a direct circuit power supply for the electrodes. The electrode wells in an array may be used in pairs or one anode well may be used with a plurality of cathode wells. The DC current flow between electrode wells may be periodically reversed which controls the formation of mineral deposits in the alkaline cathode well-bore water, as well as to help rejuvenate the catalysis.

On the Synthesis of Carbon Nanotubes from Waste Solid Hydrocarbons

NASA Astrophysics Data System (ADS)

Zhuo, Chuanwei

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. They consist of coaxial tubular graphene sheets, with diameters in the order of nanometers (1 x 10-9 m) and lengths in the order of micrometers (1 x 10-6 m). The latter can now be extended into the order of meters. Carbon nanotubes (CNTs) have been studied for more than 20 years. CNTs possess superior electrical, mechanical, thermal, chemical, and structural properties, which make their potential applications nowadays overwhelmingly widespread. Now entering into the growth phase of product life cycle, increasing usage of CNTs in commercial products is part of the beginning of the nano-technological revolution. Expanding markets for CNTs' large volume applications place ever-increasing demands on lowering their production costs to the level acceptable by the end-user applications. It is estimated that the mass application of CNTs will be facilitated only when the price of CNTs approaches that of conductive carbon black. The synthesis of CNTs involves three elements: the carbonaceous feedstocks (raw materials), the catalysts, and the necessary process power consumption. Therefore, they jointly contribute to the major operation expenditures in CNT synthesis/production. Current technologies for large-scale production of CNTs (either chemical vapor deposition, CVD, or combustion synthesis) require intensive consumption of premium feedstocks and catalysts, and the CVD process requires high energy consumption. Therefore, there is a pressing need for resource-benign and energy-benign, cost-effective nano-manufacturing processes. In the search for sustainable alternatives, it would be prudent to explore renewable and/or replenishable low-cost feedstocks, such as those found in municipal, industrial, and agricultural recycling streams. In the search for low cost catalysts, stainless steels have been proposed as cost-effective dual purpose substrates and catalysts, as they contain transition metals (iron, nickel, etc.) which are well-documented to be effective catalysts for CNT growth. In this doctoral dissertation, the feasibility of utilizing municipal / industrial / agriculture wastes as carbon sources for CNTs has been examined and proven. It was also found that the effluents of the CNT synthesis process can also serve as gaseous fuels for "clean" power production, which can then be used for energy self-sustaining CNT synthesis. Besides, a facile catalyst pre-treatment has been developed to activate stainless steel based substrate/catalyst for efficient CNT growth. Finally, the efforts of CO2 on the pyrolyzate gases and on the CNT co-generation were also investigated.

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

Hood, Zachary D.; Adhikari, Shiba P.; Li, Yunchao

Many inexpensive biofuel feedstocks, including those containing free fatty acids (FFAs) in high concentrations, are typically disposed of as waste due to our inability to efficiently convert them into usable biofuels. Here we demonstrate that carbon derived from waste tires could be functionalized with sulfonic acid (-SO 3H) to effectively catalyze the esterification of oleic acid or a mixture of fatty acids to usable biofuels. Waste tires were converted to hard carbon, then functionalized with catalytically active -SO 3H groups on the surface through an environmentally benign process that involved the sequential treatment with L-cysteine, dithiothreitol, and H 2O 2.more » In conclusion, when benchmarked against the same waste-tire derived carbon material treated with concentrated sulfuric acid at 150 °C, similar catalytic activity was observed. Both catalysts could also effectively convert oleic acid or a mixture of fatty acids and soybean oil to usable biofuels at 65 °C and 1 atm without leaching of the catalytic sites.« less

Vitamin B1-catalyzed acetoin formation from acetaldehyde: a key step for upgrading bioethanol to bulk C₄ chemicals.

PubMed

Lu, Ting; Li, Xiukai; Gu, Liuqun; Zhang, Yugen

2014-09-01

The production of bulk chemicals and fuels from renewable biobased feedstocks is of significant importance for the sustainability of human society. The production of ethanol from biomass has dramatically increased and bioethanol also holds considerable potential as a versatile building block for the chemical industry. Herein, we report a highly selective process for the conversion of ethanol to C4 bulk chemicals, such as 2,3-butanediol and butene, via a vitamin B1 (thiamine)-derived N-heterocyclic carbene (NHC)-catalyzed acetoin condensation as the key step to assemble two C2 acetaldehydes into a C4 product. The environmentally benign and cheap natural catalyst vitamin B1 demonstrates high selectivity (99%), high efficiency (97% yield), and high tolerance toward ethanol and water impurities in the acetoin reaction. The results enable a novel and efficient process for ethanol upgrading. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Achillea millefolium L. extract mediated green synthesis of waste peach kernel shell supported silver nanoparticles: Application of the nanoparticles for catalytic reduction of a variety of dyes in water.

PubMed

Khodadadi, Bahar; Bordbar, Maryam; Nasrollahzadeh, Mahmoud

2017-05-01

In this paper, silver nanoparticles (Ag NPs) are synthesized using Achillea millefolium L. extract as reducing and stabilizing agents and peach kernel shell as an environmentally benign support. FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Thermo gravimetric-differential thermal analysis (TG-DTA) and Transmission Electron Microscopy (TEM) were used to characterize peach kernel shell, Ag NPs, and Ag NPs/peach kernel shell. The catalytic activity of the Ag NPs/peach kernel shell was investigated for the reduction of 4-nitrophenol (4-NP), Methyl Orange (MO), and Methylene Blue (MB) at room temperature. Ag NPs/peach kernel shell was found to be a highly active catalyst. In addition, Ag NPs/peach kernel shell can be recovered and reused several times with no significant loss of its catalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Constructing the magnetic bifunctional graphene/titania nanosheet-based composite photocatalysts for enhanced visible-light photodegradation of MB and electrochemical ORR from polluted water.

PubMed

Zhang, Qian; Zhang, Yihe; Meng, Zilin; Tong, Wangshu; Yu, Xuelian; An, Qi

2017-09-25

Photocatalysis is a promising strategy to address the global environmental and energy challenges. However, the studies on the application of the photocatalytically degraded dye-polluted water and the multi-purpose use of one type of catalyst have remained sparse. In this report, we try to demonstrate a concept of multiple and cyclic application of materials and resources in environmentally relevant catalyst reactions. A magnetic composite catalyst prepared from exfoliated titania nanosheets, graphene, the magnetic iron oxide nanoparticles, and a polyelectrolyte enabled such a cyclic application. The composite catalyst decomposed a methylene blue-polluted water under visible light, and then the catalyst was collected and removed from the treated water using a magnet. The photocatalytically treated water was then used to prepare the electrolyte in electrochemical reductive reactions and presented superior electrochemical performance compared with the dye-polluted water. The composite catalyst was once again used as the cathode catalyst in the electrochemical reaction. Each component in the composite catalyst was indispensable in its catalytic activity, but each component played different roles in the photochemical, magnetic recycling, and electrochemical processes. We expect the report inspire the study on the multi-functional catalyst and cyclic use of the catalytically cleaned water, which should contribute for the environmental and energy remedy from a novel perspective.

Development of a general non-noble metal catalyst for the benign amination of alcohols with amines and ammonia.

PubMed

Cui, Xinjiang; Dai, Xingchao; Deng, Youquan; Shi, Feng

2013-03-11

The N-alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N-alkyl amines. However, as a potentially clean and economic choice for N-alkyl amine synthesis, non-noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCuFeOx catalyst was designed and prepared for the N-alkylation of ammonia or amines with alcohol or primary amines. N-alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N-heterocyclic compounds, and secondary amines could be N-alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one-pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uranium oxide catalysts: environmental applications for treatment of chlorinated organic waste from nuclear industry.

PubMed

Lazareva, Svetlana; Ismagilov, Zinfer; Kuznetsov, Vadim; Shikina, Nadezhda; Kerzhentsev, Mikhail

2018-02-05

Huge amounts of nuclear waste, including depleted uranium, significantly contribute to the adverse environmental situation throughout the world. An approach to the effective use of uranium oxides in catalysts for the deep oxidation of chlorine-containing hydrocarbons is suggested. Investigation of the catalytic activity of the synthesized supported uranium oxide catalysts doped with Cr, Mn and Co transition metals in the chlorobenzene oxidation showed that these catalysts are comparable with conventional commercial ones. Physicochemical properties of the catalysts were studied by X-ray diffraction, temperature-programmed reduction with hydrogen (H 2 -TPR), and Fourier transform infrared spectroscopy. The higher activity of Mn- and Co-containing uranium oxide catalysts in the H 2 -TPR and oxidation of chlorobenzene in comparison with non-uranium catalysts may be related to the formation of a new disperse phase represented by uranates. The study of chlorobenzene adsorption revealed that the surface oxygen is involved in the catalytic process.

Chemical agents for conversion of chrysotile asbestos into non-hazardous materials

DOEpatents

Sugama, Toshifumi; Petrakis, Leon

1998-06-09

A composition and methods for converting a chrysotile asbestos-containing material to a non-regulated environmentally benign solid which comprises a fluoro acid decomposing agent capable of dissociating the chrysotile asbestos to non-regulated components, wherein non-regulated components are non-reactive with the environment, and a binding agent which binds the non-regulated components to form an environmentally benign solid.

Porous Ionic Polymers as a Robust and Efficient Platform for Capture and Chemical Fixation of Atmospheric CO2.

PubMed

Sun, Qi; Jin, Yingyin; Aguila, Briana; Meng, Xiangju; Ma, Shengqian; Xiao, Feng-Shou

2017-03-22

Direct use of atmospheric CO 2 as a C 1 source to synthesize high-value chemicals through environmentally benign processes is of great interest, yet challenging. Porous heterogeneous catalysts that are capable of simultaneously capturing and converting CO 2 are promising candidates for such applications. Herein, a family of organic ionic polymers with nanoporous structure, large surface area, strong affinity for CO 2 , and very high density of catalytic active sites (halide ions) was synthesized through the free-radical polymerization of vinylfunctionalized quaternary phosphonium salts. The resultant porous ionic polymers (PIPs) exhibit excellent activities in the cycloaddition of epoxides with atmospheric CO 2 , outperforming the corresponding soluble phosphonium salt analogues and ranking among the highest of known metal-free catalytic systems. The high CO 2 uptake capacity of the PIPs facilitates the enrichment of CO 2 molecules around the catalytic centers, thereby benefiting its conversion. We have demonstrated for the first time that atmospheric CO 2 can be directly converted to cyclic carbonates at room temperature using a heterogeneous catalytic system under metal-solvent free conditions. Moreover, the catalysts proved to be robust and fully recyclable, demonstrating promising potential for practical utilization for the chemical fixation of CO 2 . Our work thereby paves a way to the advance of PIPs as a new type of platform for capture and conversion of CO 2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrolytic cleavage of both CS2 carbon-sulfur bonds by multinuclear Pd(II) complexes at room temperature

NASA Astrophysics Data System (ADS)

Jiang, Xuan-Feng; Huang, Hui; Chai, Yun-Feng; Lohr, Tracy Lynn; Yu, Shu-Yan; Lai, Wenzhen; Pan, Yuan-Jiang; Delferro, Massimiliano; Marks, Tobin J.

2017-02-01

Developing homogeneous catalysts that convert CS2 and COS pollutants into environmentally benign products is important for both fundamental catalytic research and applied environmental science. Here we report a series of air-stable dimeric Pd complexes that mediate the facile hydrolytic cleavage of both CS2 carbon-sulfur bonds at 25 °C to produce CO2 and trimeric Pd complexes. Oxidation of the trimeric complexes with HNO3 regenerates the dimeric starting complexes with the release of SO2 and NO2. Isotopic labelling confirms that the carbon and oxygen atoms of CO2 originate from CS2 and H2O, respectively, and reaction intermediates were observed by gas-phase and electrospray ionization mass spectrometry, as well as by Fourier transform infrared spectroscopy. We also propose a plausible mechanistic scenario based on the experimentally observed intermediates. The mechanism involves intramolecular attack by a nucleophilic Pd-OH moiety on the carbon atom of coordinated µ-OCS2, which on deprotonation cleaves one C-S bond and simultaneously forms a C-O bond. Coupled C-S cleavage and CO2 release to yield [(bpy)3Pd3(µ3-S)2](NO3)2 (bpy, 2,2‧-bipyridine) provides the thermodynamic driving force for the reaction.

Chemical agents for conversion of chrysotile asbestos into non-hazardous materials

DOEpatents

Sugama, Toshifumi; Petrakis, L.

1998-06-09

A composition and methods are disclosed for converting a chrysotile asbestos-containing material to a non-regulated environmentally benign solid which comprises a fluoro acid decomposing agent capable of dissociating the chrysotile asbestos to non-regulated components, wherein non-regulated components are non-reactive with the environment, and a binding agent which binds the non-regulated components to form an environmentally benign solid. 2 figs.

Hydrogenation and dehydrogenation iron pincer catalysts capable of metal-ligand cooperation by aromatization/dearomatization.

PubMed

Zell, Thomas; Milstein, David

2015-07-21

The substitution of expensive and potentially toxic noble-metal catalysts by cheap, abundant, environmentally benign, and less toxic metals is highly desirable and in line with green chemistry guidelines. We have recently discovered a new type of metal-ligand cooperation, which is based on the reversible dearomatization/aromatization of different heteroaromatic ligand cores caused by deprotonation/protonation of the ligand. More specifically, we have studied complexes of various transition metals (Ru, Fe, Co, Rh, Ir, Ni, Pd, Pt, and Re) bearing pyridine- and bipyridine-based PNP and PNN pincer ligands, which have slightly acidic methylene protons. In addition, we have discovered long-range metal-ligand cooperation in acridine-based pincer ligands, where the cooperation takes place at the electrophilic C-9 position of the acridine moiety leading to dearomatization of its middle ring. This type of metal-ligand cooperation was used for the activation of chemical bonds, including H-H, C-H (sp(2) and sp(3)), O-H, N-H, and B-H bonds. This unusual reactivity likely takes place in various catalytic hydrogenation, dehydrogenation, and related reactions. In this Account, we summarize our studies on novel bifunctional iron PNP and PNN pincer complexes, which were designed on the basis of their ruthenium congeners. Iron PNP pincer complexes serve as efficient (pre)catalysts for hydrogenation and dehydrogenation reactions under remarkably mild conditions. Their catalytic applications include atom-efficient and industrially important hydrogenation reactions of ketones, aldehydes, and esters to the corresponding alcohols. Moreover, they catalyze the hydrogenation of carbon dioxide to sodium formate in the presence of sodium hydroxide, the selective decomposition of formic acid to carbon dioxide and hydrogen, and the E-selective semihydrogenation of alkynes to give E-alkenes. These catalysts feature, compared to other iron-based catalysts, very high catalytic activities which in some cases can even exceed those of state-of-the-art noble-metal catalysts. For the iron PNP systems, we describe the synthesis of the pyridine- and acridine-based PNP iron complexes and their performances and limitations in catalytic reactions, and we present studies on their reactivity with relevance to their catalytic mechanisms. In the case of the bipyridine-based PNN system, we summarize the synthesis of new complexes and describe studies on the noninnocence of the methylene position, which can be reversibly deprotonated, as well as on the noninnocence of the bipyridine unit. Overall, this Account underlines that the combination of cheap and abundant iron with ligands that are capable of metal-ligand cooperation can result in the development of novel, versatile, and efficient catalysts for atom-efficient catalytic reactions.

Options and processes for spent catalyst handling and utilization.

PubMed

Marafi, M; Stanislaus, A

2003-07-18

The quantity of spent hydroprocessing catalysts discarded as solid wastes in the petroleum refining industries has increased remarkably in recent years due to a rapid growth in the hydroprocessing capacity to meet the rising demand for low-sulfur fuels. Due to their toxic nature, spent hydroprocessing catalysts have been branded as hazardous wastes, and the refiners are experiencing pressure from environmental authorities to handle them safely. Several alternative methods such as reclamation of metals, rejuvenation and reuse, disposal in landfills and preparation of useful materials using spent catalysts as raw materials are available to deal with the spent catalyst problem. The technical feasibility as well as the environmental and economic aspects of these options are reviewed. In addition, details of two bench-scale processes, one for rejuvenation of spent hydroprocessing catalysts, and the other for producing non-leachable synthetic aggregate materials that were developed in this laboratory, are presented in this paper.

The Origin and Significance of Mammary Intraductal Foam Cells

DTIC Science & Technology

2005-09-01

hematopoeitic origin developed in mammary tissue with both benign and malignant differentiation, depending on environmental cues. Progression of the cells...contribution of hematopoeitic precursors to the heterogeneity of cell types in benign and malignant mammary tissue.

Applications of polymeric smart materials to environmental problems.

PubMed Central

Gray, H N; Bergbreiter, D E

1997-01-01

New methods for the reduction and remediation of hazardous wastes like carcinogenic organic solvents, toxic materials, and nuclear contamination are vital to environmental health. Procedures for effective waste reduction, detection, and removal are important components of any such methods. Toward this end, polymeric smart materials are finding useful applications. Polymer-bound smart catalysts are useful in waste minimization, catalyst recovery, and catalyst reuse. Polymeric smart coatings have been developed that are capable of both detecting and removing hazardous nuclear contaminants. Such applications of smart materials involving catalysis chemistry, sensor chemistry, and chemistry relevant to decontamination methodology are especially applicable to environmental problems. PMID:9114277

The capacity of modified nickel catalysts derived from discharged catalyst of fertilizer plants for NOx treatment

NASA Astrophysics Data System (ADS)

Ha, T. M. P.; Luong, N. T.; Le, P. N.

2016-11-01

In Vietnam for recent years, a large amount of hazardous waste containing nickel (Ni) derived from discharged catalyst of fertilizer plants has caused environmental problems in landfill overloading and the risk of soil or surface water sources pollution. Taking advantage of discharged catalyst, recycling Ni components and then synthesizing new catalysts apply for mono-nitrogen oxides (NOx) treatments is an approach to bring about both economic and environmental benefits. This study was carried out with the main objective: Evaluate the performance of modified catalysts (using recovered Ni from the discharged RKS-2-7H catalyst of Phu My Fertilizer Plant) on NOx treatment. The catalysts was synthesized and modified with active phases consist of recovered Ni and commercial Barium oxide (BaO), Manganese dioxide (MnO2) / Cerium (IV) oxide (CeO2) on the support Aluminium oxide (γ-Al2O3). The results show that the modified catalysts with Ni, Ba, Ce was not more beneficial for NOx removal than which with Ni, Ba, Mn. 98% NOx removal at 350°C with the start temperature at 115°C and the T60 value at 307°C can be obtained with 10Ni10Ba10Mn/Al catalyst.

Design and preparation of plant oil-based polymers and their applications

NASA Astrophysics Data System (ADS)

Ahn, Byung-Jun Kollbe

Renewable materials are desirable for many applications due to the finite fossil resources and environmental issues. Plant oil is one of the most promising renewable feedstocks. Plant oils and functionalized oleo-chemicals including functionalized soybean oils have become attractive sustainable chemicals for industrial applications. Especially, epoxidized oleo-chemicals such as epoxidized soybean oil (ESO) are one of the most well-known readily available inexpensive functionalized plant oils. In this study, novel polymers and nanocomposites for sustainable materials applications were designed and prepared via ring-opening of epoxide in plant oils, and their chemical and physical properties were characterized. The novel transparent elastomers derived from functionalized plant oils have a great potential as flexible electronic and biological applications with their inherent low toxicity. Especially, their rheological properties showed a potential for pressure sensitive adhesives (PSAs). The dominant thermal stability and transparency were obtained via green processing: one pot, single step, fast reactions in moderate conditions, or solvent-free UV curing conditions. These oleo-based elastomers presented excellent end-use properties for PSAs application comparable to commercial PSA tapes. Based on the principal chemical studies, the roles of the each component have been identified: polymer derived from the ring-opening of epoxides as an elastomer, and dihydroxylated triglycerides as a tackifier. Their interaction was also elucidated with an element label analysis. The mechanical and rheological properties of the oleo-polymer as PSAs were able to be improved with a rosin ester tackifier. In addition, biogreases and bio-thermoplastics were developed via the environmentally benign process, which will contribute to further application on the production of new bio-based materials. Further, this study essays a novel acid functionalized iron/iron oxide nanoparticles catalyst with excellent product yields for epoxide ring opening of oleochemicals for a greener synthetic method of biopolyols, and excellent environmental benefits with life cycle assessment of syntheses. Those functionalized iron/iron oxide core shell nanoparticles catalysts has great potential for biomedical engineering process with the highest magnetization of Fe(0) core among all metals.

MICROWAVE-ASSISTED GREENER SYNTHESIS OF PHARMACEUTICALLY ACTIVE HETEROCYCLES UNDER BENIGN CONDITIONS

EPA Science Inventory

Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies. Environmentally benign protocols have been developed for the synthesis of various pharmaceutically active heterocycles namely ...

Magnetic cobaltic nanoparticle-anchored carbon nanocomposite derived from cobalt-dipicolinic acid coordination polymer: An enhanced catalyst for environmental oxidative and reductive reactions.

PubMed

Wu, Chang-Hsun; Lin, Jyun-Ting; Lin, Kun-Yi Andrew

2018-05-01

Direct carbonization of cobalt complexes represents as a convenient approach to prepare magnetic carbon/cobalt nanocomposites (MCCNs) as heterogeneous environmental catalysts. However, most of MCCNs derived from consist of sheet-like carbon matrices with very sparse cobaltic nanoparticles (NPs), making them exhibit relatively low catalytic activities, porosity and magnetism. In this study, dipicolinic acid (DPA) is selected to prepare a 3-dimensional cobalt coordination polymer (CoDPA). MCCN derived from CoDPA can consist of a porous carbon matrix embedded with highly-dense Co 0 and Co 3 O 4 NPs. This magnetic Co 0 /Co 3 O 4 NP-anchored carbon composite (MCNC) appears as a promising heterogeneous catalyst for oxidative and reductive environmental catalytic reactions. As peroxymonosulfate (PMS) activation is selected as a model catalytic oxidative reaction, MCNC exhibits a much higher catalytic activity than Co 3 O 4 , a benchmark catalyst for PMS activation. The reductive catalytic activity of MCNC is demonstrated through 4-nitrophenol (4-NP) reduction in the presence of NaBH 4 . MCNC could rapidly react with NaBH 4 to generate H 2 for hydrogenation of 4-NP to 4-aminophenol (4-AP). In comparison with other precious metallic catalysts, MCNC also shows a relatively high catalytic activity. These results indicate that MCNC is a conveniently prepared and highly effective and stable carbon-supported cobaltic heterogeneous catalyst for versatile environmental catalytic applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Recycling of woven carbon-fibre-reinforced polymer composites using supercritical water.

PubMed

Knight, Chase C; Zeng, Changchun; Zhang, Chuck; Wang, Ben

2012-01-01

Over the past few years, there has been great deal of interest in recycling carbon-fibre-reinforced polymer composites. One method that has shown promising results involves the use of supercritical fluids to achieve separation between matrix and fibres by effectively degrading the resin into lower molecular weight compounds. In addition, the solvents used are environmentally benign and can also be recovered and reused. In this study, supercritical water with 0.05 M KOH as the catalyst was used for the recycling of an aerospace-grade high-performance epoxy carbon fibre composite (Hexcel 8552/IM7). The morphology of the reclaimed fibres was observed by scanning electron microscopy, and the tensile properties of the fibres were measured by single filament testing. The effects of processing time on the resin elimination efficiency and fibre property retention were investigated. With the process developed in this research, as much as 99.2 wt% resin elimination was achieved, resulting in the recovery of clean, undamaged fibres. The reclaimed fibres retained the original tensile strength. The feasibility of recycling multiple layer composites was also explored.

Template-free fabrication of hierarchically flower-like tungsten trioxide assemblies with enhanced visible-light-driven photocatalytic activity.

PubMed

Yu, Jiaguo; Qi, Lifang

2009-09-30

Hierarchically flower-like tungsten trioxide assemblies were fabricated on a large scale by a simple hydrothermal treatment of sodium tungstate in aqueous solution of nitric acid. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and N(2) adsorption-desorption measurements. The photocatalytic activity was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that the three-dimensional tungsten trioxide assemblies were constructed from two-dimensional layers, which were further composed of a large number of interconnected lathy nanoplates with different sizes. Such flower-like assemblies exhibited hierarchically porous structure and higher visible-light photocatalytic activity than the samples without such hierarchical structures due to their specific hierarchical pores that served as the transport paths for light and reactants. After five recycles for the photodegradation of RhB, the catalyst did not exhibit any great loss in activity, confirming hierarchically flower-like tungsten trioxide was stability and not photocorroded. This study may provide new insight into environmentally benign preparation and design of novel photocatalytic materials and enhancement of photocatalytic activity.

Plasma-assisted catalytic storage reduction system

DOEpatents

Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

2000-01-01

A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

Plasma-assisted catalytic storage reduction system

DOEpatents

Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

2002-01-01

A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

SELECTIVE OXIDATION OF ALCOHOLS OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE

EPA Science Inventory

Oxidation of various alcohols is studied in liquid phase under nitrogen atmosphere over vanadium phosphorus oxide catalyst in an environmentally friendly protocol using hydrogen peroxide. The catalyst and the method are found to be suitable for the selective oxidation of a variet...

CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts

NASA Technical Reports Server (NTRS)

Herz, Richard K.

1990-01-01

Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

PubMed Central

Xie, Zaiku; Liu, Zhicheng; Wang, Yangdong; Yang, Qihua; Xu, Longya; Ding, Weiping

2010-01-01

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts. PMID:20559508

Fe3O4@MOF core-shell magnetic microspheres as excellent catalysts for the Claisen-Schmidt condensation reaction

NASA Astrophysics Data System (ADS)

Ke, Fei; Qiu, Ling-Guang; Zhu, Junfa

2014-01-01

Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this work, we present a facile fabrication and characterization of a novel type of MOF-based porous catalyst, namely, Fe3O4@MIL-100(Fe) core-shell magnetic microspheres. It has been shown that these catalysts not only exhibit high catalytic activities for the Claisen-Schmidt condensation reactions under environmentally friendly conditions, but remarkably, they can be easily separated and recycled without significant loss of catalytic efficiency after being used for many times. Therefore, compared to other reported catalysts used in the Claisen-Schmidt condensation reactions, these catalysts are green, cheap and more suitable for large scale industrial applications.Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this work, we present a facile fabrication and characterization of a novel type of MOF-based porous catalyst, namely, Fe3O4@MIL-100(Fe) core-shell magnetic microspheres. It has been shown that these catalysts not only exhibit high catalytic activities for the Claisen-Schmidt condensation reactions under environmentally friendly conditions, but remarkably, they can be easily separated and recycled without significant loss of catalytic efficiency after being used for many times. Therefore, compared to other reported catalysts used in the Claisen-Schmidt condensation reactions, these catalysts are green, cheap and more suitable for large scale industrial applications. Electronic supplementary information (ESI) available: SEM and TEM images, and GC-MS spectra for chalcones. See DOI: 10.1039/c3nr05051c

Catalysts for cleaner combustion of coal, wood and briquettes sulfur dioxide reduction options for low emission sources

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

Smith, P.V.

1995-12-31

Coal fired, low emission sources are a major factor in the air quality problems facing eastern European cities. These sources include: stoker-fired boilers which feed district heating systems and also meet local industrial steam demand, hand-fired boilers which provide heat for one building or a small group of buildings, and masonary tile stoves which heat individual rooms. Global Environmental Systems is marketing through Global Environmental Systems of Polane, Inc. catalysts to improve the combustion of coal, wood or fuel oils in these combustion systems. PCCL-II Combustion Catalysts promotes more complete combustion, reduces or eliminates slag formations, soot, corrosion and somemore » air pollution emissions and is especially effective on high sulfur-high vanadium residual oils. Glo-Klen is a semi-dry powder continuous acting catalyst that is injected directly into the furnace of boilers by operating personnel. It is a multi-purpose catalyst that is a furnace combustion catalyst that saves fuel by increasing combustion efficiency, a cleaner of heat transfer surfaces that saves additional fuel by increasing the absorption of heat, a corrosion-inhibiting catalyst that reduces costly corrosion damage and an air pollution reducing catalyst that reduces air pollution type stack emissions. The reduction of sulfur dioxides from coal or oil-fired boilers of the hand fired stoker design and larger, can be controlled by the induction of the Glo-Klen combustion catalyst and either hydrated lime or pulverized limestone.« less

Metal-Free Cataluminescence Gas Sensor for Hydrogen Sulfide Based on Its Catalytic Oxidation on Silicon Carbide Nanocages.

PubMed

Wu, Liqian; Zhang, Lichun; Sun, Mingxia; Liu, Rui; Yu, Lingzhu; Lv, Yi

2017-12-19

Cataluminescence- (CTL-) based sensors are among the most attractive and effective tools for gas sensing, owing to their efficient selectivity, high sensitivity, and rapidity. As the sensing materials of CTL-based sensors, metal-based catalysts easily bring about high costs and environmental pollution of heavy metals. More importantly, the long-term stability of metal-based catalysts is usually rather poor. Metal-free catalysts have unique advantages such as environmental friendliness, low costs, and long-term stability, making them promising materials for CTL-based sensors. Herein, we report the fabrication of a CTL sensor based on a metal-free catalyst. F-doped cage-like SiC was synthesized by wet chemical etching. The as-prepared products showed a rapid, stable, highly selective, and sensitive cataluminescent response to H 2 S. The stability of the sensor was demonstrated to be fairly good for at least 15 days. After CTL tests, F-doped cage-like SiC retained its original morphology, structure, and chemical composition. In addition, to the best of our knowledge, this is the first report of a metal-free CTL sensor. Metal-free catalysts are environmentally friendly and low in cost and exhibit long-term stability, which could open a new avenue of CTL sensing.

Isomerization of glucose into fructose by environmentally friendly Fe/β zeolite catalysts.

PubMed

Xu, Siquan; Zhang, Lei; Xiao, Kehao; Xia, Haian

2017-06-29

Herein, the environmentally friendly Fe/β zeolite for glucose isomerization to fructose in aqueous media was reported for the first time. The effects of various reaction conditions including reaction temperature, reaction time, catalyst dosage, etc. on the isomerization reaction over Fe/β zeolite were studied in detail. Under the optimized conditions, yield of fructose higher than 20% were obtained. Moreover, the Fe/β zeolite catalysts were stable and remained constant catalytic activity after five consecutive runs. The possible active Fe species for isomerization of glucose in Fe/β zeolite is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

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

Kristine L. Lowe; Bill W. Bogan; Wendy R. Sullivan

2004-07-30

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing indicated that the growth, and the metal corrosion caused by pure cultures of sulfate reducing bacteria were inhibited by hexane extracts of some pepper plants. This quarter tests were performed with mixed bacterialmore » cultures obtained from natural gas pipelines. Treatment with the pepper extracts affected the growth and metabolic activity of the microbial consortia. Specifically, the growth and metabolism of sulfate reducing bacteria was inhibited. The demonstration that pepper extracts can inhibit the growth and metabolism of sulfate reducing bacteria in mixed cultures is a significant observation validating a key hypothesis of the project. Future tests to determine the effects of pepper extracts on mature/established biofilms will be performed next.« less

POLLUTION PREVENTION IN INDUSTRIAL CONDENSATION REACTIONS

EPA Science Inventory

The objective of this project is to develop heterogeneous acid-base catalysts to increase the economic and environmental performance of the current homogeneous catalysts used to make industrially important condensation products. Such products include methyl isobutyl ketone ...

Presidential Green Chemistry Challenge: 2016 Greener Synthetic Pathways Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2016 award winners, Albemarle and CB&I, developed a safer technology to produce alkylate, a clean gasoline component by replacing liquid acid catalysts with a lower environmental impact catalyst

Manganese complex-catalyzed oxidation and oxidative kinetic resolution of secondary alcohols by hydrogen peroxide† †Electronic supplementary information (ESI) available: Tables S1–S4 and additional data: NMR spectra of the products, GC and HPLC chromatograms in the OKR of secondary alcohols, key geometric information for DFT, etc. See DOI: 10.1039/c7sc00891k Click here for additional data file.

PubMed Central

Miao, Chengxia; Li, Xiao-Xi; Lee, Yong-Min; Xia, Chungu; Wang, Yong

2017-01-01

The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn–oxo species. Density functional theory calculations revealed the difference in reaction energy barriers for H-atom abstraction from the α-CH bonds of R- and S-enantiomers by a chiral high-valent manganese–oxo complex, supporting the experimental result from the OKR of secondary alcohols. PMID:29163900

Contact Us

Science.gov Websites

SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing (ERC ) ** Bringing Sustainability to Semiconductor Manufacturing ** A multi-university research center leading the way to environmentally friendly semiconductor manufacturing, sponsored by the Semiconductor Research

Use of reagents to convert chrysotile and amosite asbestos used as insulation or protection for metal surfaces

DOEpatents

Sugama, Toshifumi; Petrakis, Leon

2000-12-12

A composition for converting asbestos-containing material, covering metal pipes or other metal surfaces, to non-regulated, environmentally benign-materials, and inhibiting the corrosion of the metal pipes or other metal surfaces. The composition comprises a combination of at least two multiple-functional group reagents, in which each reagent includes a Fluro acid component and a corrosion inhibiting compoment. A method for converting asbestos-containing material, covering metal pipes or other metal surfaces, to non-regulated, environmentally benign-materials, and inhibiting the corrosion of the metal pipes or other metal surfaces is also provided.

Bio‐palladium: from metal recovery to catalytic applications

PubMed Central

De Corte, Simon; Hennebel, Tom; De Gusseme, Bart; Verstraete, Willy; Boon, Nico

2012-01-01

Summary While precious metals are available to a very limited extent, there is an increasing demand to use them as catalyst. This is also true for palladium (Pd) catalysts and their sustainable recycling and production are required. Since Pd catalysts exist nowadays mostly under the form of nanoparticles, these particles need to be produced in an environment‐friendly way. Biological synthesis of Pd nanoparticles (‘bio‐Pd’) is an innovative method for both metal recovery and nanocatalyst synthesis. This review will discuss the different bio‐Pd precipitating microorganisms, the applications of the catalyst (both for environmental purposes and in organic chemistry) and the state of the art of the reactors based on the bio‐Pd concept. In addition, some main challenges are discussed, which need to be overcome in order to create a sustainable nanocatalyst. Finally, some outlooks for bio‐Pd in environmental technology are presented. PMID:21554561

Waste cockle shell as natural catalyst for biodiesel production from jatropha oil

NASA Astrophysics Data System (ADS)

Hadi, Norulakmal Nor; Idrus, Nur Afini; Ghafar, Faridah; Salleh, Marmy Roshaidah Mohd

2017-12-01

Due to the increasing of industrialization and modernization of the world, the demand of petroleum has risen rapidly. The increasing demand for energy and environmental awareness has prompted many researches to embark on alternative fuel platforms that are environmentally acceptable. In this study, jatropha oil was used to produce biodiesel by a new transesterification routine in which cockle shell was used as source of heterogeneous catalyst. The investigation showed the catalyst that was calcined at temperature of 800 °C has the optimum capability to produce high yield. The highest yield of biodiesel production of 93.20 % were obtained by using 1.5 wt% of catalyst. The reaction was conducted at a temperature of 65 °C with the optimum methanol to oil ratio of 6:1. It was found that the physical properties of the biodiesel produced were significant to ASTM standard of fatty acid methyl ester (FAME).

Green heterogeneous Pd(II) catalyst produced from chitosan-cellulose micro beads for green synthesis of biaryls.

PubMed

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

2016-11-05

In green catalyst systems, both the catalyst and the technique should be environmentally safe. In this study we designed a green palladium(II) catalyst for microwave-assisted Suzuki CC coupling reactions. The catalyst support was produced from biopolymers; chitosan and cellulose. The catalytic activity of the catalyst was tested on 16 substrates in solvent-free media and compared with those of commercial palladium salts. Reusability tests were done. The catalyst was also used in conventional reflux-heating system to demonstrate the efficiency of microwave heating method. We recorded high activity, selectivity and excellent TONs (6600) and TOFs (82500) just using a small catalyst loading (1.5×10(-3)mol%) in short reaction time (5min). The catalyst exhibited a long lifetime (9 runs). The findings indicated that both green chitosan/cellulose-Pd(II) catalyst and the microwave heating are suitable for synthesis of biaryl compounds by using Suzuki CC coupling reactions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Efficient reduction of CO2 to CO with high current density using in situ or ex situ prepared Bi-based materials.

PubMed

Medina-Ramos, Jonnathan; DiMeglio, John L; Rosenthal, Joel

2014-06-11

The development of inexpensive electrocatalysts that can promote the reduction of CO2 to CO with high selectivity, efficiency, and large current densities is an important step on the path to renewable production of liquid carbon-based fuels. While precious metals such as gold and silver have historically been the most active cathode materials for CO2 reduction, the price of these materials precludes their use on the scale required for fuel production. Bismuth, by comparison, is an affordable and environmentally benign metal that shows promise for CO2 conversion applications. In this work, we show that a bismuth-carbon monoxide evolving catalyst (Bi-CMEC) can be formed under either aqueous or nonaqueous conditions using versatile electrodeposition methods. In situ formation of this thin-film catalyst on an inexpensive carbon electrode using an organic soluble Bi(3+) precursor streamlines preparation of this material and generates a robust catalyst for CO2 reduction. In the presence of appropriate imidazolium based ionic liquid promoters, the Bi-CMEC platform can selectively catalyze conversion of CO2 to CO without the need for a costly supporting electrolyte. This inexpensive system can catalyze evolution of CO with current densities as high as jCO = 25-30 mA/cm(2) and attendant energy efficiencies of ΦCO ≈ 80% for the cathodic half reaction. These metrics highlight the efficiency of Bi-CMEC, since only noble metals have been previously shown to promote this fuel forming half reaction with such high energy efficiency. Moreover, the rate of CO production by Bi-CMEC ranges from approximately 0.1-0.5 mmol·cm(-2)·h(-1) at an applied overpotential of η ≈ 250 mV for a cathode with surface area equal to 1.0 cm(2). This CO evolution activity is much higher than that afforded by other non-noble metal cathode materials and distinguishes Bi-CMEC as a superior and inexpensive platform for electrochemical conversion of CO2 to fuel.

Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

PubMed

Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

2016-05-24

Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems.

ERC Membership/Boards

Science.gov Websites

SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing (ERC ) ** Bringing Sustainability to Semiconductor Manufacturing ** A multi-university research center leading the way to environmentally friendly semiconductor manufacturing, sponsored by the Semiconductor Research

Multifunctional Au-Fe3O4@MOF core-shell nanocomposite catalysts with controllable reactivity and magnetic recyclability

NASA Astrophysics Data System (ADS)

Ke, Fei; Wang, Luhuan; Zhu, Junfa

2014-12-01

The recovery and reuse of expensive catalysts are important in both heterogeneous and homogeneous catalysis due to economic and environmental reasons. This work reports a novel multifunctional magnetic core-shell gold catalyst which can be easily prepared and shows remarkable catalytic properties in the reduction of 4-nitrophenol. The novel Au-Fe3O4@metal-organic framework (MOF) catalyst consists of a superparamagnetic Au-Fe3O4 core and a porous MOF shell with controllable thickness. Small Au nanoparticles (NPs) of 3-5 nm are mainly sandwiched between the Fe3O4 core and the porous MOF shell. Catalytic studies show that the core-shell structured Au-Fe3O4@MOF catalyst has a much higher catalytic activity than other reported Au-based catalysts toward the reduction of 4-nitrophenol. Moreover, this catalyst can be easily recycled due to the presence of the superparamagnetic core. Therefore, compared to conventional catalysts used in the reduction of 4-nitrophenol, this porous MOF-based magnetic catalyst is green, cheap and promising for industrial applications.The recovery and reuse of expensive catalysts are important in both heterogeneous and homogeneous catalysis due to economic and environmental reasons. This work reports a novel multifunctional magnetic core-shell gold catalyst which can be easily prepared and shows remarkable catalytic properties in the reduction of 4-nitrophenol. The novel Au-Fe3O4@metal-organic framework (MOF) catalyst consists of a superparamagnetic Au-Fe3O4 core and a porous MOF shell with controllable thickness. Small Au nanoparticles (NPs) of 3-5 nm are mainly sandwiched between the Fe3O4 core and the porous MOF shell. Catalytic studies show that the core-shell structured Au-Fe3O4@MOF catalyst has a much higher catalytic activity than other reported Au-based catalysts toward the reduction of 4-nitrophenol. Moreover, this catalyst can be easily recycled due to the presence of the superparamagnetic core. Therefore, compared to conventional catalysts used in the reduction of 4-nitrophenol, this porous MOF-based magnetic catalyst is green, cheap and promising for industrial applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05421k

Sustainable Catalysis_Energy efficient reactions and Applications

EPA Science Inventory

This book chapter discusses various catalysts for environmental remediation. Detailed information on catalysis using ferrate and ferrite oxidation, TiO2 photocatalysis, and new catalysts (i.e., graphene, perovskites and graphitic carbon nitride) is provided for the degradation of...

Application, Deactivation, and Regeneration of Heterogeneous Catalysts in Bio-Oil Upgrading

DOE PAGES

Cheng, Shouyun; Wei, Lin; Zhao, Xianhui; ...

2016-12-07

The massive consumption of fossil fuels and associated environmental issues are leading to an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two of the most promising bio-oil upgrading processes for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although advances have been achieved, the deactivation and regeneration of catalysts still remains a challenge. This review focuses on the current progress and challenges of heterogeneous catalyst application, deactivation, and regeneration. The technologies of catalysts deactivation, reduction,more » and regeneration for improving catalyst activity and stability are discussed. Some suggestions for future research including catalyst mechanism, catalyst development, process integration, and biomass modification for the production of hydrocarbon biofuels are provided.« less

Application, Deactivation, and Regeneration of Heterogeneous Catalysts in Bio-Oil Upgrading

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

Cheng, Shouyun; Wei, Lin; Zhao, Xianhui

The massive consumption of fossil fuels and associated environmental issues are leading to an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two of the most promising bio-oil upgrading processes for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although advances have been achieved, the deactivation and regeneration of catalysts still remains a challenge. This review focuses on the current progress and challenges of heterogeneous catalyst application, deactivation, and regeneration. The technologies of catalysts deactivation, reduction,more » and regeneration for improving catalyst activity and stability are discussed. Some suggestions for future research including catalyst mechanism, catalyst development, process integration, and biomass modification for the production of hydrocarbon biofuels are provided.« less

On-demand Hydrogen Production from Organosilanes at Ambient Temperature Using Heterogeneous Gold Catalysts

NASA Astrophysics Data System (ADS)

Mitsudome, Takato; Urayama, Teppei; Kiyohiro, Taizo; Maeno, Zen; Mizugaki, Tomoo; Jitsukawa, Koichiro; Kaneda, Kiyotomi

2016-11-01

An environmentally friendly (“green”), H2-generation system was developed that involved hydrolytic oxidation of inexpensive organosilanes as hydrogen storage materials with newly developed heterogeneous gold nanoparticle catalysts. The gold catalyst functioned well at ambient temperature under aerobic conditions, providing efficient production of pure H2. The newly developed size-selective gold nanoparticle catalysts could be separated easily from the reaction mixture containing organosilanes, allowing an on/off-switchable H2-production by the introduction and removal of the catalyst. This is the first report of an on/off-switchable H2-production system employing hydrolytic oxidation of inexpensive organosilanes without requiring additional energy.

A Phosphine-mediated Synthesis of 2,3,4,5-tetra-substituted N-hydroxypyrroles from α-oximino Ketones and Dialkyl Acetylenedicarboxylates Under Ionic Liquid Green-media.

PubMed

Shahvelayati, Ashraf S; Ghazvini, Maryam; Yadollahzadeh, Khadijeh; Delbari, Akram S

2018-01-01

The development of multicomponent reactions (MCRs) in the presence of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also as catalysts, is a new approach that meet with the requirements of sustainable chemistry. In recent years, the use of ionic liquids as a green media for organic synthesis has become a chief study area. This is due to their unique properties such as non-volatility, non-flammability, chemical and thermal stability, immiscibility with both organic compounds and water and recyclability. Ionic liquids are used as environmentally friendly solvents instead of hazardous organic solvents. We report the condensation reaction between α-oximinoketone and dialkyl acetylene dicarboxylate in the presence of triphenylphosphine to afford substituted pyrroles under ionic liquid conditions in good yields. Densely functionalized pyrroles was easily prepared from reaction of α-oximinoketones, dialkyl acetylene dicarboxylate in the presence of triphenylphosphine in a quantitative yield under ionic liquid conditions at room temperature. In conclusion, ionic liquids are indicated as a useful and novel reaction medium for the selective synthesis of functionalized pyrroles. This reaction medium can replace the use of hazardous organic solvents. Easy work-up, synthesis of polyfunctional compounds, decreased reaction time, having easily available-recyclable ionic liquids, and good to high yields are advantages of present method. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

DE-FG02-96ER20226 FinalTechnicalReport

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

Lidstrom, M E

In the future, environmental concerns will mandate that manufacturing processes shift towards the use of renewable resources and the minimization of wastes, especially hazardous wastes. One-carbon compounds are of interest as feedstocks for synthesis of chemicals and materials, because they represent a relatively inexpensive, abundant and renewable resource. In addition, the environmentally-benign characteristics of microbial processes make them of interest as part of a long-term waste-minimization strategy for industry. The concept that methylotrophic bacteria could serve as non-polluting multistage catalysts to generate chemicals and materials using C1 compounds as feedstocks is a highly attractive one. In order to develop productionmore » strains of methylotrophs, it is necessary to understand and manipulate central methylotrophic pathways. One of the most important of these is the methanol oxidation, or Mox system. In this project, we are studying the promoters and transcriptional regulation of this 25-gene system in Methylobacterium extorquens AM1, a facultative methanol-utilizer. We have addressed the significance of a hexanucleotide sequence upstream of all mox promoters and have shown that it is required for activity of these promoters using both deletion and mutational analyses. In addition, we have identified a putative hairpin structure in the RNA leader region of the mxa promoter that is also essential for transcriptional, and have assessed the mechanism of action of this regulatory region. This work is providing the foundation for development of methylotrophic strains to convert methanol into higher value added products.« less

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

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

Bill W. Bogan; Brigid M. Lamb; Gemma Husmillo

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Various chemicals that inhibit the growth and/or the metabolism of corrosion-associated microbes such as sulfate reducing bacteria, denitrifying bacteria, and methanogenic bacteria were evaluated to determine their ability to inhibit corrosion in experiments utilizing puremore » and mixed bacterial cultures, and planktonic cultures as well as mature biofilms. Planktonic cultures are easier to inhibit than mature biofilms but several compounds were shown to be effective in decreasing the amount of metal corrosion. Of the compounds tested hexane extracts of Capsicum pepper plants and molybdate were the most effective inhibitors of sulfate reducing bacteria, bismuth nitrate was the most effective inhibitor of nitrate reducing bacteria, and 4-((pyridine-2-yl)methylamino)benzoic acid (PMBA) was the most effective inhibitor of methanogenic bacteria. All of these compounds were demonstrated to minimize corrosion due to MIC, at least in some circumstances. The results obtained in this project are consistent with the hypothesis that any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion. This approach of controlling MIC by controlling the metabolism of biofilms is more environmentally benign than the current approach involving the use of potent biocides, and warrants further investigation.« less

Prevalence and heritability of psoriasis and benign migratory glossitis in one Brazilian population.

PubMed

Jorge, Maria Augusta; Gonzaga, Heron Fernando de Sousa; Tomimori, Jane; Picciani, Bruna Lavinas Sayed; Barbosa, Calógeras Antônio

2017-01-01

An oral condition associated to psoriasis is benign migratory glossitis. The review of the literature does not show any publication about heritability in both soriasis and benign migratory glossitis and prevalence of psoriasis in the Brazilian population. This research was carried out in order to determine the prevalence of psoriasis and benign migratory glossitis in the Brazilian population from a Brazilian sample, as well as the heritability in these conditions. Six thousand patients were studied from the records of the outpatient dermatology department. The sample had 129 patients with cutaneous psoriasis, 399 with benign migratory glossitis without psoriasis and a control group with 5,472 patients. After data collection, the statistical analysis was made using Woolf, Chi-square and Falconer tests. The prevalence of psoriasis was 2.15% and the benign migratory glossitis was 7.0%. The prevalence of benign migratory glossitis in the psoriasis group was high (16.3%), and that was statistically significant. Family history in the psoriasis group was 38% for the condition itself and 2,75% for benign migratory glossitis and in the benign migratory glossitis group was 17.54% for the condition itself and 1.5% for psoriasis. The study of heritability was 38.8% for psoriasis and 36.6% for benign migratory glossitis, both with medium heritability. This study was only in the state of São Paulo. This is the first publication that quantifies how much of these conditions have a genetic background and how important the environmental factors are in triggering them.

DESIGNING ENVIRONMENTALLY BENIGN SOLVENT SUBSTITUTES

EPA Science Inventory

Since the signing of 1987 Montreal Protocol, reducing and eliminating the use of harmful solvents has become an internationally imminent environmental protection mission. Solvent substitution is an effective way to achieve this goal. The Program for Assisting the Replacement of...

GREENING OF OXIDATION CATALYSIS THROUGH IMPROVED CATALYST AND PROCESS DESIGN

EPA Science Inventory

Greening of Oxidation Catalysis Through Improved Catalysts and Process Design
Michael A. Gonzalez*, Thomas Becker, and Raymond Smith

United State Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W...

Use Of Superacids To Digest Chrysotile And Amosite Asbestos In Simple Mixtures Or Matrices Found In Building Materials Compositions

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

Sugama, Toshifumi; Petrakis, Leon; Webster, Ronald P.

A composition for converting asbestos-containing material to environmentally benign components is provided. The composition comprises a flouro acid decomposing agent which can be applied to either amosite-containing thermal insulation or chrysotile-containing fire-proof material or to any asbestos-containing material which includes of chrysotile and amosite asbestos. The fluoro acid decomposing agent includes FP(O)(OH).sub.2, hexafluorophosphoric acid, a mixture of hydrofluoric and phosphoric acid and a mixture of hexafluorophosphoric acid and phosphoric acid. A method for converting asbestos-containing material to environmentally benign components is also provided

Use of super acids to digest chrysotile and amosite asbestos in simple mixtures or matrices found in building materials compositions

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

Sugama, T.; Petrakis, L.; Webster, R.P.

A composition for converting asbestos-containing material to environmentally benign components is provided. The composition comprises a fluoro acid decomposing agent which can be applied to either amosite-containing thermal insulation or chrysotile-containing fire-proof material or to any asbestos-containing material which includes of chrysotile and amosite asbestos. The fluoro acid decomposing agent includes FP{sub 0}(OH){sub 2}, hexafluorophosphoric acid, a mixture of hydrofluoric and phosphoric acid and a mixture of hexafluorophosphoric acid and phosphoric acid. A method for converting asbestos-containing material to environmentally benign components is also provided.

Toward environmentally-benign utilization of nonmetallic fraction of waste printed circuit boards as modifier and precursor.

PubMed

Hadi, Pejman; Ning, Chao; Ouyang, Weiyi; Xu, Meng; Lin, Carol S K; McKay, Gordon

2015-01-01

Electronic waste, including printed circuit boards, is growing at an alarming rate due to the accelerated technological progress and the shorter lifespan of the electronic equipment. In the past decades, due to the lack of proper economic and environmentally-benign recycling technologies, a major fraction of e-waste generated was either destined to landfills or incinerated with the sole intention of its disposal disregarding the toxic nature of this waste. Recently, with the increasing public awareness over their environment and health issues and with the enaction of more stringent regulations, environmentally-benign recycling has been driven to be an alternative option partially replacing the traditional eco-unfriendly disposal methods. One of the most favorable green technologies has been the mechanical separation of the metallic and nonmetallic fraction of the waste printed circuit boards. Although metallic fraction, as the most profitable component, is used to generate the revenue of the separation process, the nonmetallic fraction (NMF) has been left isolated. Herein, the recent developments in the application of NMF have been comprehensively reviewed and an eco-friendly emerging usage of NMF as a value-added material for sustainable remediation has been introduced. Copyright © 2014 Elsevier Ltd. All rights reserved.

HOMOGENEOUS AIR OXIDATION OF HYDROCARBONS UTILIZING MN AND CO CATALYSTS

EPA Science Inventory

Homogeneous Air Oxidation of Hydrocarbons Utilizing Mn and Co Catalysts

Thomas M. Becker and Michael A. Gonzalez*, Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26 West Martin Luther King Drive, Mail Sto...

Nucleation, growth, and repair of a cobalt-based oxygen evolving catalyst.

PubMed

Surendranath, Yogesh; Lutterman, Daniel A; Liu, Yi; Nocera, Daniel G

2012-04-11

The mechanism of nucleation, steady-state growth, and repair is investigated for an oxygen evolving catalyst prepared by electrodeposition from Co(2+) solutions in weakly basic electrolytes (Co-OEC). Potential step chronoamperometry and atomic force microscopy reveal that nucleation of Co-OEC is progressive and reaches a saturation surface coverage of ca. 70% on highly oriented pyrolytic graphite substrates. Steady-state electrodeposition of Co-OEC exhibits a Tafel slope approximately equal to 2.3 × RT/F. The electrochemical rate law exhibits a first order dependence on Co(2+) and inverse orders on proton (third order) and proton acceptor, methylphosphonate (first order for 1.8 mM ≤ [MeP(i)] ≤ 18 mM and second order dependence for 32 mM ≤ [MeP(i)] ≤ 180 mM). These electrokinetic studies, combined with recent XAS studies of catalyst structure, suggest a mechanism for steady state growth at intermediate MeP(i) concentration (1.8-18 mM) involving a rapid solution equilibrium between aquo Co(II) and Co(III) hydroxo species accompanied with a rapid surface equilibrium involving electrolyte dissociation and deprotonation of surface bound water. These equilibria are followed by a chemical rate-limiting step for incorporation of Co(III) into the growing cobaltate clusters comprising Co-OEC. At higher concentrations of MeP(i) ([MeP(i)] ≥ 32 mM), MePO(3)(2-) equilibrium binding to Co(II) in solution is suggested by the kinetic data. Consistent with the disparate pH profiles for oxygen evolution electrocatalysis and catalyst formation, NMR-based quantification of catalyst dissolution as a function of pH demonstrates functional stability and repair at pH values >6 whereas catalyst corrosion prevails at lower pH values. These kinetic insights provide a basis for developing and operating functional water oxidation (photo)anodes under benign pH conditions. © 2012 American Chemical Society

SYSTEMATIC PROCEDURE FOR DESIGNING PROCESSES WITH MULTIPLE ENVIRONMENTAL OBJECTIVES

EPA Science Inventory

Evaluation of multiple objectives is very important in designing environmentally benign processes. It requires a systematic procedure for solving multiobjective decision-making problems, due to the complex nature of the problems, the need for complex assessments, and complicated ...

Pyrolysis of marine biomass to produce bio-oil and its upgrading using a novel multi-metal catalyst prepared from the spent car catalytic converter.

PubMed

Sabegh, Mahzad Yaghmaei; Norouzi, Omid; Jafarian, Sajedeh; Khosh, Akram Ghanbari; Tavasoli, Ahmad

2018-02-01

In order to reduce the economic and environmental consequences caused by spent car catalyst, we herein report for the first time a novel promising multi-metal catalyst prepared from spent car catalytic converters to upgrade the pyrolysis bio-oils. The physico-chemical properties of prepared catalyst were characterized by XRD, EDS, FESEM, and FT-IR analyses. The thermal stability of the multi-metal catalyst was studied with TGA. To investigate the activity of the catalyst, Conversion of Cladophora glomerata (C. glomerata) into bio-products was carried out via a fixed bed reactor with and without catalyst at the temperature of 500°C. Although the catalyst didn't catalyze the gasification reaction, bio-oil was upgraded over the catalyst. The main effect of the catalyst on the bio-oil components is deoxygenating of nitrogen compounds and promotion the ketonization reaction, which converts acid to ketone and declines the corrosive nature of bio-oil. Copyright © 2017. Published by Elsevier Ltd.

Stability of High-Performance Pt-Based Catalysts for Oxygen Reduction Reactions.

PubMed

Lin, Rui; Cai, Xin; Zeng, Hao; Yu, Zhuoping

2018-04-01

Due to their environmental sustainability and high efficiency, proton-exchange-membrane fuel cells (PEMFCs) are expected to be an essential type of energy source for electric vehicles, energy generation, and the space industry in the coming decades. Here, the recent developments regarding shape-controlled nanostructure catalysts are reviewed, with a focus on the stability of high-performance Pt-based catalysts and related mechanisms. The catalysts, which possess great activity, are still far from meeting the requirements of their applications, due to stability issues, especially in membrane electrode assemblies (MEAs). Thus, solutions toward the comprehensive performance of Pt-based catalysts are discussed here. The research trends and related theories that can promote the application of Pt-based catalysts are also provided. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Submicron sized water-stable metal organic framework (bio-MOF-11) for catalytic degradation of pharmaceuticals and personal care products.

PubMed

Azhar, Muhammad Rizwan; Vijay, Periasamy; Tadé, Moses O; Sun, Hongqi; Wang, Shaobin

2018-04-01

Water-stable and active metal organic frameworks (MOFs) are important materials for mitigation of water contaminants via adsorption and catalytic reactions. In this study, a highly water-stable Co-based MOF, namely bio-MOF-11-Co, was synthesized by a simplified benign method. Moreover, it was used as a catalyst in successful activation of peroxymonsulfate for catalytic degradation of sulfachloropyradazine (SCP) and para-hydroxybenzoic acid (p-HBA) as representatives of pharmaceuticals and personal care products, respectively. The bio-MOF-11-Co showed rapid degradation of both p-HBA and SCP and could be reused multiple times without losing the activity by simply water washing. The effects of catalyst and PMS loadings as well as temperature were further studied, showing that high catalyst and PMS loadings as well as temperature produced faster kinetic degradation of p-HBA and SCP. The generation of highly reactive and HO radicals during the degradation was investigated by quenching tests and electron paramagnetic resonance. A plausible degradation mechanism was proposed based on the functionalities in the bio-MOF-11-Co. The availability of electron rich nucleobase adenine reinforced the reaction kinetics by electron donation along with cobalt atoms in the bio-MOF-11-Co structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

PubMed

Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

2018-06-01

In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

Catalyst. Volume 11, Number 2, Spring 2010

ERIC Educational Resources Information Center

Ryan, Barbara E., Ed.

2010-01-01

"Catalyst" is a publication of the U.S. Department of Education's Higher Education Center for Alcohol and Other Drug Abuse and Violence Prevention. This issue contains the following articles: (1) Redefining Resources For Prevention; (2) Message From Kevin Jennings, OSDFS Assistant Deputy Secretary; (3) Environmental Management…

Green Synthesis of Nanomaterials: Environmental Aspects

EPA Science Inventory

There is always a search for reliable and environmentally friendly processes to manufacture metal and metal oxide nanoparticles minimizing or even eliminating the use of hazardous chemicals. The only way to develop these “green” processes is to adapt benign synthesis approaches t...

ON DEVELOPING TOOLS AND METHODS FOR ENVIRONMENTALLY BENIGN PROCESSES

EPA Science Inventory

Two types of tools are generally needed for designing processes and products that are cleaner from environmental impact perspectives. The first kind is called process tools. Process tools are based on information obtained from experimental investigations in chemistry., material s...

Pyrometallurgical Recovery of Platinum Group Metals from Spent Catalysts

NASA Astrophysics Data System (ADS)

Peng, Zhiwei; Li, Zhizhong; Lin, Xiaolong; Tang, Huimin; Ye, Lei; Ma, Yutian; Rao, Mingjun; Zhang, Yuanbo; Li, Guanghui; Jiang, Tao

2017-09-01

As an important secondary resource with abundant platinum group metals (PGMs), spent catalysts demand recycling for both economic and environmental benefits. This article reviews the main pyrometallurgical processes for PGM recovery from spent catalysts. Existing processes, including smelting, vaporization, and sintering processes, are discussed based in part on a review of the physiochemical characteristics of PGMs in spent catalysts. The smelting technology, which produces a PGM-containing alloy, is significantly influenced by the addition of various collectors, such as lead, copper, iron, matte, or printed circuit board (PCB), considering their chemical affinities for PGMs. The vaporization process can recover PGMs in vapor form at low temperatures (250-700°C), but it suffers high corrosion and potential environmental and health risks as a result of involvement of the hazardous gases, mainly Cl2 and CO. The sintering process serves as a reforming means for recycling of the spent catalysts by in situ reduction of their oxidized PGMs components. Among these processes, the smelting process seems more promising although its overall performance can be further improved by seeking a suitable target-oriented collector and flux, together with proper pretreatment and process intensification using an external field.

Prevalence and heritability of psoriasis and benign migratory glossitis in one Brazilian population*

PubMed Central

Jorge, Maria Augusta; Gonzaga, Heron Fernando de Sousa; Tomimori, Jane; Picciani, Bruna Lavinas Sayed; Barbosa, Calógeras Antônio

2017-01-01

Background An oral condition associated to psoriasis is benign migratory glossitis. The review of the literature does not show any publication about heritability in both soriasis and benign migratory glossitis and prevalence of psoriasis in the Brazilian population. Objective This research was carried out in order to determine the prevalence of psoriasis and benign migratory glossitis in the Brazilian population from a Brazilian sample, as well as the heritability in these conditions. Methods Six thousand patients were studied from the records of the outpatient dermatology department. The sample had 129 patients with cutaneous psoriasis, 399 with benign migratory glossitis without psoriasis and a control group with 5,472 patients. After data collection, the statistical analysis was made using Woolf, Chi-square and Falconer tests. Results The prevalence of psoriasis was 2.15% and the benign migratory glossitis was 7.0%. The prevalence of benign migratory glossitis in the psoriasis group was high (16.3%), and that was statistically significant. Family history in the psoriasis group was 38% for the condition itself and 2,75% for benign migratory glossitis and in the benign migratory glossitis group was 17.54% for the condition itself and 1.5% for psoriasis. The study of heritability was 38.8% for psoriasis and 36.6% for benign migratory glossitis, both with medium heritability. Study limitations This study was only in the state of São Paulo. Conclusion This is the first publication that quantifies how much of these conditions have a genetic background and how important the environmental factors are in triggering them. PMID:29364438

Microwave-Assisted Rapid Access to Bio-active Heterocycles: Synthesis of 1,3,4-Oxadiazoles, 1,3,4-Thiadiazoles, 1,3-Dioxanes, Pyrazoles, Hydrazones and 3,4-Dihydropyrimidin-2(1H)-ones under Benign Conditions

EPA Science Inventory

Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies.1 It emphasis the use of highly efficient and environmental benign synthetic protocols to deliver bio-active heterocycles, acc...

Geomaterials: their application to environmental remediation

PubMed Central

Yamada, Hirohisa; Tamura, Kenji; Watanabe, Yujiro; Iyi, Nobuo; Morimoto, Kazuya

2011-01-01

Geomaterials are materials inspired by geological systems originating from the billion years long history of the Earth. This article reviews three important classes of geomaterials. The first one is smectites—layered silicates with a cation-exchange capacity. Smectites are useful for removing pollutants and as intercalation compounds, catalysts and polymer nanocomposites. The second class is layered double hydroxides (LDHs). They have an anion-exchange capacity and are used as catalysts, catalyst precursors, sorbents and scavengers for halogens. The third class of geomaterials is zeolites—microporous materials with a cation-exchange capacity which are used for removing harmful cations. Zeolite composites with LDHs can absorb ammonium and phosphate ions in rivers and lakes, whereas zeolite/apatite composites can immobilize the radioactive iodine. These geomaterials are essential for environmental remediation. PMID:27877455

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

A SYSTEMATIC PROCEDURE FOR DESIGNING PROCESSES WITH MULTIPLE ENVIRONMENTAL OBJECTIVES

EPA Science Inventory

Evaluation and analysis of multiple objectives are very important in designing environmentally benign processes. They require a systematic procedure for solving multi-objective decision-making problems due to the complex nature of the problems and the need for complex assessment....

In-use catalyst surface area and its relation to HC conversion efficiency and FTP emissions

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

Donahue, K.S.; Sabourin, M.A.; Larson, R.E.

1986-01-01

Surface area data, steady-state hydrocarbon conversion efficiency data, and hydrocarbon emissions results have been determined for catalysts collected by the U.S. Environmental Protection Agency from properly maintained 1981 and 1982 model year vehicles. Catalysts covered in this study were limited to those with three-way-plus-oxidation monolith technologies. Catalyst surface areas were measured using the BET method, conversion efficiencies were measured on an exhaust gas generator, and emissions results were determined using the Urban Driving Schedule of the Federal Test Procedure. Results indicate that correlation of catalyst surface area data with hydrocarbon conversion efficiency data and hydrocarbon emissions results is significant formore » the sample studied.« less

OXIDATION OF ALCOHOLS OVER FE3+/MONTMORILLONITE-K10 USING HYDROGEN PEROXIDE

EPA Science Inventory

Oxidation of various primary and secondary alcohols is studied in liquid phase at atmospheric pressure over Fe3+/montmorillonite-K10 catalyst prepared by ion-exchange method at a pH of 4 in an environmentally friendly protocol using hydrogen peroxide. The catalyst and the method ...

EXPOXIDATION OF OLEFINS AND α,β-UNSATURATED KEYTONES OVER SONOCHEMICALLY PREPARED HYDROXYAPATITES USING HYDROGEN PEROXIDE

EPA Science Inventory

An effective and environmentally friendly protocol for the epoxidation of olefins and α,β-unsaturated ketones in the presence of hydroxyapatite as catalyst using hydrogen peroxide is described. The catalyst is active and reusable for the selective epoxidation of a variety...

EXTRACTION OF PENTACHLOROPHENOL (PCP) FROM SOILS USING ENVIRONMENTALLY BENIGN ACID SOLUTIONS

EPA Science Inventory

The presence of organic contaminants like PCP in soil is a major environmental concern. Various remediation methods have been used of which soil washing is a common procedure. Many different solvents like surfactants, ionic liquids and cyclodextrins have been studied. the pres...

Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications

NASA Astrophysics Data System (ADS)

Pham, Tung Ngoc; Samikannu, Ajaikumar; Kukkola, Jarmo; Rautio, Anne-Riikka; Pitkänen, Olli; Dombovari, Aron; Lorite, Gabriela Simone; Sipola, Teemu; Toth, Geza; Mohl, Melinda; Mikkola, Jyri-Pekka; Kordas, Krisztian

2014-11-01

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m2g-1 to ~345 m2g-1, while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 +/- 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications.

PubMed

Pham, Tung Ngoc; Samikannu, Ajaikumar; Kukkola, Jarmo; Rautio, Anne-Riikka; Pitkänen, Olli; Dombovari, Aron; Lorite, Gabriela Simone; Sipola, Teemu; Toth, Geza; Mohl, Melinda; Mikkola, Jyri-Pekka; Kordas, Krisztian

2014-11-06

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m(2)g(-1) to ~345 m(2)g(-1), while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 ± 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Engineering Cofactor Preference of Ketone Reducing Biocatalysts: A Mutagenesis Study on a γ-Diketone Reductase from the Yeast Saccharomyces cerevisiae Serving as an Example

PubMed Central

Katzberg, Michael; Skorupa-Parachin, Nàdia; Gorwa-Grauslund, Marie-Françoise; Bertau, Martin

2010-01-01

The synthesis of pharmaceuticals and catalysts more and more relies on enantiopure chiral building blocks. These can be produced in an environmentally benign and efficient way via bioreduction of prochiral ketones catalyzed by dehydrogenases. A productive source of these biocatalysts is the yeast Saccharomyces cerevisiae, whose genome also encodes a reductase catalyzing the sequential reduction of the γ-diketone 2,5-hexanedione furnishing the diol (2S,5S)-hexanediol and the γ-hydroxyketone (5S)-hydroxy-2-hexanone in high enantio- as well as diastereoselectivity (ee and de >99.5%). This enzyme prefers NADPH as the hydrogen donating cofactor. As NADH is more stable and cheaper than NADPH it would be more effective if NADH could be used in cell-free bioreduction systems. To achieve this, the cofactor binding site of the dehydrogenase was altered by site-directed mutagenesis. The results show that the rational approach based on a homology model of the enzyme allowed us to generate a mutant enzyme having a relaxed cofactor preference and thus is able to use both NADPH and NADH. Results obtained from other mutants are discussed and point towards the limits of rationally designed mutants. PMID:20480039

A Single-Chamber Microbial Fuel Cell without an Air Cathode

PubMed Central

Nimje, Vanita Roshan; Chen, Chien-Cheng; Chen, Hau-Ren; Chen, Chien-Yen; Tseng, Min-Jen; Cheng, Kai-Chien; Shih, Ruey-Chyuan; Chang, Young-Fo

2012-01-01

Microbial fuel cells (MFCs) represent a novel technology for wastewater treatment with electricity production. Electricity generation with simultaneous nitrate reduction in a single-chamber MFC without air cathode was studied, using glucose (1 mM) as the carbon source and nitrate (1 mM) as the final electron acceptor employed by Bacillus subtilis under anaerobic conditions. Increasing current as a function of decreased nitrate concentration and an increase in biomass were observed with a maximum current of 0.4 mA obtained at an external resistance (Rext) of 1 KΩ without a platinum catalyst of air cathode. A decreased current with complete nitrate reduction, with further recovery of the current immediately after nitrate addition, indicated the dependence of B. subtilis on nitrate as an electron acceptor to efficiently produce electricity. A power density of 0.0019 mW/cm2 was achieved at an Rext of 220 Ω. Cyclic voltammograms (CV) showed direct electron transfer with the involvement of mediators in the MFC. The low coulombic efficiency (CE) of 11% was mainly attributed to glucose fermentation. These results demonstrated that electricity generation is possible from wastewater containing nitrate, and this represents an alternative technology for the cost-effective and environmentally benign treatment of wastewater. PMID:22489190

Removal of sulphur-containing odorants from fuel gases for fuel cell-based combined heat and power applications

NASA Astrophysics Data System (ADS)

de Wild, P. J.; Nyqvist, R. G.; de Bruijn, F. A.; Stobbe, E. R.

Natural gas (NG) and liquefied petroleum gas (LPG) are important potential feedstocks for the production of hydrogen for fuel cell-based (e.g. proton exchange membrane fuel cells (PEMFC) or solid oxide fuel Cells (SOFC) combined heat and power (CHP) applications. To prevent detrimental effects on the (electro)catalysts in fuel cell-based combined heat and power installations (FC-CHP), sulphur removal from the feedstock is mandatory. An experimental bench-marking study of adsorbents has identified several candidates for the removal of sulphur containing odorants at low temperature. Among these adsorbents a new material has been discovered that offers an economically attractive means to remove TetraHydroThiophene (THT), the main European odorant, from natural gas at ambient temperature. The material is environmentally benign, easy to use and possesses good activity (residual sulphur levels below 20 ppbv) and capacity for the common odorant THT in natural gas. When compared to state-of-the-art metal-promoted active carbon the new material has a THT uptake capacity that is up to 10 times larger, depending on temperature and pressure. Promoted versions of the new material have shown potential for the removal of THT at higher temperatures and/or for the removal of other odorants such as mercaptans from natural gas or from LPG.

ENVIRONMENTALLY BENIGN MITIGATION OF MICROBIOLOGICALLY INFLUENCED CORROSION (MIC)

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

J. Robert Paterek; Gemma Husmillo

The overall program objective is to develop and evaluate environmental benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is one or more environmental benign, a.k.a. ''green'' products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Capsicum sp. extracts and pure compounds were screened for their antimicrobial activity against MIC causing bacteria. Studies on the ability of these compounds to dissociate biofilm from the substratum were conducted using microtiter plate assays. Tests usingmore » laboratory scale pipeline simulators continued. Preliminary results showed that the natural extracts possess strong antimicrobial activity being comparable to or even better than the pure compounds tested against strains of sulfate reducers. Their minimum inhibitory concentrations had been determined. It was also found that they possess bactericidal properties at minimal concentrations. Biofilm dissociation activity as assessed by microtiter plate assays demonstrated varying degrees of differences between the treated and untreated group with the superior performance of the extracts over pure compounds. Such is an indication of the possible benefits that could be obtained from these natural products. Confirmatory experiments are underway.« less

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

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

J. Robert Paterek; Gemma Husmillo

The overall program objective is to develop and evaluate environmental benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is one or more environmental benign, a.k.a. ''green'' products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Capsicum sp. extracts and pure compounds were screened for their antimicrobial activity against MIC causing bacteria. Studies on the ability of these compounds to dissociate biofilm from the substratum were conducted using microtiter plate assays. Tests usingmore » laboratory scale pipeline simulators continued. Preliminary results showed that the natural extracts possess strong antimicrobial activity being comparable to or even better than the pure compounds tested against strains of sulfate reducers. Their minimum inhibitory concentrations had been determined. It was also found that they possess bactericidal properties at minimal concentrations. Biofilm dissociation activity as assessed by microtiter plate assays demonstrated varying degrees of differences between the treated and untreated group with the superior performance of the extracts over pure compounds. Such is an indication of the possible benefits that could be obtained from these natural products. Confirmatory experiments are underway.« less

EVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

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

Bill W. Bogan; Wendy R. Sullivan; Kristine M. H. Cruz

2004-04-30

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing of pepper extracts resulted in preliminary data indicating that some pepper extracts inhibit the growth of some corrosion-associated microorganisms. This quarter additional tests were performed to more specifically investigate the ability of threemore » pepper extracts to inhibit the growth, and to influence the metal corrosion caused by two microbial species: Desulfovibrio vulgaris, and Comomonas denitrificans. All three pepper extracts rapidly killed Desulfovibrio vulgaris, but did not appear to inhibit Comomonas denitrificans. While corrosion rates were at control levels in experiments with Desulfovibrio vulgaris that received pepper extract, corrosion rates were increased in the presence of Comomonas denitrificans plus pepper extract. Further testing with a wider range of pure bacterial cultures, and more importantly, with mixed bacterial cultures should be performed to determine the potential effectiveness of pepper extracts to inhibit MIC.« less

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

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

Bill W. Bogan; Brigid M. Lamb; John J. Kilbane II

2004-10-30

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing indicated that the growth, and the metal corrosion caused by pure cultures of sulfate reducing bacteria were inhibited by hexane extracts of some pepper plants. This quarter tests were performed to determine ifmore » chemical compounds other than pepper extracts could inhibit the growth of corrosion-associated microbes and to determine if pepper extracts and other compounds can inhibit corrosion when mature biofilms are present. Several chemical compounds were shown to be capable of inhibiting the growth of corrosion-associated microorganisms, and all of these compounds limited the amount of corrosion caused by mature biofilms to a similar extent. It is difficult to control corrosion caused by mature biofilms, but any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion.« less

Environmental transmission electron microscopy for catalyst materials using a spherical aberration corrector.

PubMed

Takeda, Seiji; Kuwauchi, Yasufumi; Yoshida, Hideto

2015-04-01

Atomic resolution has been obtained using environmental transmission electron microscopy (ETEM) by installing a spherical aberration corrector (Cs-corrector) on the objective lens. Simultaneously, the technology for controlling the environment around a specimen in ETEM has advanced significantly in the past decade. Quantification methodology has recently been established for deriving relevant experimental data in catalyst materials from substantial and systematic ETEM observation at the atomic scale. With this background, this paper summarizes aspects of the evolutional microscopy technique: necessary conditions for atomic resolution in ETEM; reduction of the scattering of electrons by the medium surrounding a specimen; and an environmental cell for structural imaging of a crystalline specimen. The high spatial resolution of a Cs-corrected ETEM is demonstrated for different observation conditions. After statistical analysis combined with numerical image analysis of ETEM data is briefly described, the recent applications of the Cs-corrected ETEM to catalyst materials are reviewed. For gold nanoparticulate catalysts, the structural information on the reaction sites and adsorption sites are deduced. For Pt nanoparticulate catalysts, ETEM studies elucidate the correlation between the catalytic activity and the morphology of the nanoparticles. These studies also reveal oxidation and reduction on the topmost Pt surface layer at the atomic scale. Finally, current issues and the future perspectives of Cs-corrected ETEM are summarized, including the reproducibility of ETEM observation data, the control of environments, the critical evaluation of electron irradiation effects, the full implementation of transmission electron microscopy technology in ETEM, and the safety issues for an ETEM laboratory. Copyright © 2014 Elsevier B.V. All rights reserved.

Glymes as benign co-solvents for CaO-catalyzed transesterification of soybean oil to biodiesel.

PubMed

Tang, Shaokun; Zhao, Hua; Song, Zhiyan; Olubajo, Olarongbe

2013-07-01

The base (such as CaO)-catalyzed heterogeneous preparation of biodiesel encounters a number of obstacles including the need for CaO pretreatment and the reactions being incomplete (typically 90-95% yields). In this study, a number of glymes were investigated as benign solvents for the CaO-catalyzed transesterification of soybean oil into biodiesel with a high substrate loading (typically soybean oil >50% v/v). The triglyceride-dissolving capability of glymes led to a much faster reaction rate (>98% conversions in 4h) than in methanol alone (typically 24h) and minimized the saponification reaction when catalyzed by anhydrous CaO or commercial lime without pre-activation. The use of glyme (e.g. P2) as co-solvent also activates commercial lime to become an effective catalyst without calcination pretreatment. The SEM images suggest a dissolution-agglomeration process of CaO surface in the presence of P2, which could remove the CaCO3 and Ca(OH)2 layer coated on the surface of lime. Copyright © 2013 Elsevier Ltd. All rights reserved.

Eco-Spirituality and Religion: Catalysts for Transformation in Environmental Education

ERIC Educational Resources Information Center

Crowe, Jessica L.

2011-01-01

The focus of this research was to determine methodologies in environmental education that would promote transformation in each student leading to improved personal pro-environmental behaviors. Incorporating spirituality and religious themes in environmental education is a way to link learners to their meaning systems. Research has shown that…

Catalytic Synthesis of Oxygenates: Mechanisms, Catalysts and Controlling Characteristics

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

Klier, Kamil; Herman, Richard G

2005-11-30

This research focused on catalytic synthesis of unsymmetrical ethers as a part of a larger program involving oxygenated products in general, including alcohols, ethers, esters, carboxylic acids and their derivatives that link together environmentally compliant fuels, monomers, and high-value chemicals. The catalysts studied here were solid acids possessing strong Brnsted acid functionalities. The design of these catalysts involved anchoring the acid groups onto inorganic oxides, e.g. surface-grafted acid groups on zirconia, and a new class of mesoporous solid acids, i.e. propylsulfonic acid-derivatized SBA-15. The former catalysts consisted of a high surface concentration of sulfate groups on stable zirconia catalysts. Themore » latter catalyst consists of high surface area, large pore propylsulfonic acid-derivatized silicas, specifically SBA-15. In both cases, the catalyst design and synthesis yielded high concentrations of acid sites in close proximity to one another. These materials have been well-characterization in terms of physical and chemical properties, as well as in regard to surface and bulk characteristics. Both types of catalysts were shown to exhibit high catalytic performance with respect to both activity and selectivity for the bifunctional coupling of alcohols to form ethers, which proceeds via an efficient SN2 reaction mechanism on the proximal acid sites. This commonality of the dual-site SN2 reaction mechanism over acid catalysts provides for maximum reaction rates and control of selectivity by reaction conditions, i.e. pressure, temperature, and reactant concentrations. This research provides the scientific groundwork for synthesis of ethers for energy applications. The synthesized environmentally acceptable ethers, in part derived from natural gas via alcohol intermediates, exhibit high cetane properties, e.g. methylisobutylether with cetane No. of 53 and dimethylether with cetane No. of 55-60, or high octane properties, e.g. diisopropylether with blending octane No. of 105, and can replace aromatics in liquid fuels.« less

Direct synthesis of ethanol from dimethyl ether and syngas over combined H-Mordenite and Cu/ZnO catalysts.

PubMed

Li, Xingang; San, Xiaoguang; Zhang, Yi; Ichii, Takashi; Meng, Ming; Tan, Yisheng; Tsubaki, Noritatsu

2010-10-25

Ethanol was directly synthesized from dimethyl ether (DME) and syngas with the combined H-Mordenite and Cu/ZnO catalysts that were separately loaded in a dual-catalyst bed reactor. Methyl acetate (MA) was formed by DME carbonylation over the H-Mordenite catalyst. Thereafter, ethanol and methanol were produced by MA hydrogenation over the Cu/ZnO catalyst. With the reactant gas containing 1.0% DME, the optimized temperature for the reaction was at 493 K to reach 100% conversion. In the products, the yield of methanol and ethanol could reach 46.3% and 42.2%, respectively, with a small amount of MA, ethyl acetate, and CO(2). This process is environmentally friendly as the main byproduct methanol can be recycled to DME by a dehydration reaction. In contrast, for the physically mixed catalysts, the low conversion of DME and high selectivity of methanol were observed.

Silicene Catalyzed Reduction of Nitrobenzene to Aniline: a Computational Study

NASA Astrophysics Data System (ADS)

Morrissey, Christopher; He, Haiying

The reduction of nitrobenzene to aniline has a broad range of applications in the production of rubbers, dyes, agrochemicals, and pharmaceuticals. Currently, use of metal catalysts is the most popular method of performing this reaction on a large scale. These metal catalysts usually require high-temperature and/or high-pressure reaction conditions, and produce hazardous chemicals. This has led to a call for more environmentally friendly nonmetal catalysts. Recent studies suggest that silicene, the recently discovered silicon counterpart of graphene, could potentially work as a nonmetal catalyst due to its unique electronic property and strong interactions with molecules containing nitrogen and oxygen. In this computational study, we have investigated the plausibility of using silicene as a catalyst for the reduction of nitrobenzene. Possible reaction mechanisms will be discussed with a highlight of the difference between silicene and metal catalysts. . All calculations were performed in the framework of density functional theory.

Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

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

Cha, Jennifer N.; Wang, Joseph

2014-08-31

The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds,more » (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely controlled, the nanocrystals boast a defined shape, morphology, orientation and size and are synthesized at benign reaction conditions. Adapting the methods of biomineralization towards the synthesis of platinum nanocrystals will allow effective control at a molecular level of the synthesis of highly active metal electrocatalysts, with readily tailored properties, through tuning of the biochemical inputs. The proposed research will incorporate many facets of biomineralization by: (1) isolating peptides that selectively bind particular crystal faces of platinum (2) isolating peptides that promote the nucleation and growth of particular nanocrystal morphologies (3) using two-dimensional DNA scaffolds to control the spatial orientation and density of the platinum nucleating peptides, and (4) combining bio-templating and soluble peptides to control crystal nucleation, orientation, and morphology. The resulting platinum nanocrystals will be evaluated for their electrocatalytic behavior (on common carbon supports) to determine their optimal size, morphology and crystal structure. We expect that such rational biochemical design will lead to highly uniform and efficient platinum nanocrystal catalysts for fuel cell applications.« less

Metal-free carbon materials-catalyzed sulfate radical-based advanced oxidation processes: A review on heterogeneous catalysts and applications.

PubMed

Zhao, Qingxia; Mao, Qiming; Zhou, Yaoyu; Wei, Jianhong; Liu, Xiaocheng; Yang, Junying; Luo, Lin; Zhang, Jiachao; Chen, Hong; Chen, Hongbo; Tang, Lin

2017-12-01

In recent years, advanced oxidation processes (AOPs), especially sulfate radical based AOPs have been widely used in various fields of wastewater treatment due to their capability and adaptability in decontamination. Recently, metal-free carbon materials catalysts in sulfate radical production has been more and more concerned because these materials have been demonstrated to be promising alternatives to conventional metal-based catalysts, but the review of metal-free catalysts is rare. The present review outlines the current state of knowledge on the generation of sulfate radical using metal-free catalysts including carbon nanotubes, graphene, mesoporous carbon, activated carbon, activated carbon fiber, nanodiamond. The mechanism such as the radical pathway and non-radical pathway, and factors influencing of the activation of sulfate radical was also be revealed. Knowledge gaps and research needs have been identified, which include the perspectives on challenges related to metal-free catalyst, heterogeneous metal-free catalyst/persulfate systems and their potential in practical environmental remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Platinum Group Metal-free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells.

PubMed

Yuan, Heyang; He, Zhen

2017-07-01

Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS 2 , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Gold Nanoparticles Using Tea: A Green Chemistry Experiment

ERIC Educational Resources Information Center

Sharma, R. K.; Gulati, Shikha; Mehta, Shilpa

2012-01-01

Assimilating green chemistry principles in nanotechnology is a developing area of nanoscience research nowadays. Thus, there is a growing demand to develop environmentally friendly and sustainable methods for the synthesis of nanoparticles that utilize nontoxic chemicals, environmentally benign solvents, and renewable materials to avoid their…

CATALYTIC OXIDATION OF ALCOHOLS AND EPOXIDATION OF OLEFINS WITH HYDROGEN PEROXIDE AS OXIDANT

EPA Science Inventory

Hydrogen peroxide (H2O2) is an ideal oxidant of choice for these oxidations due to economic and environmental reasons by giving water as a by-product. Two catalysts used are vanadium phosphorus oxide (VPO) and Fe3+/montmorillonite-K10 catalyst prepared by ion-exchange method at a...

Dead Wolves, Dead Birds, and Dead Trees: Catalysts for Transformative Learning in the Making of Scientist-Environmentalists

ERIC Educational Resources Information Center

Walter, Pierre

2013-01-01

This historical study identifies catalysts for transformative learning in the lives of three scientist-environmentalists important to the 20th-century environmental movement: Aldo Leopold, Rachel Carson, and David Suzuki. Following a brief review of theoretical perspectives on transformative learning, the article argues that transformative…

Environmental implications of iron fuel borne catalysts and their effects on diesel particulate formation and composition

EPA Science Inventory

Metal fuel borne catalysts can be used with diesel fuels to effectively reduce engine out particle mass emissions. Mixed with the fuel, the metals become incorporated as nanometer-scale occlusions with soot during its formation and are available to promote in-cylinder soot oxida...

Refinery catalysts: Coping with performance anxiety

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

Shelley, S.

1994-04-01

Petroleum refiners worldwide are struggling to comply with environmental mandates that tightly dictate the composition of gasoline and diesel fuel. At the same time, many are trying to capitalize on cost advantages offered by heavy, dirty feedstocks. This is stimulating development in catalysts for resid cracking, isomerization, alkylation and hydrotreating. The paper briefly describes development efforts.

Family History of Cancer in Benign Brain Tumor Subtypes Versus Gliomas

PubMed Central

Ostrom, Quinn T.; McCulloh, Christopher; Chen, Yanwen; Devine, Karen; Wolinsky, Yingli; Davitkov, Perica; Robbins, Sarah; Cherukuri, Rajesh; Patel, Ashokkumar; Gupta, Rajnish; Cohen, Mark; Barrios, Jaime Vengoechea; Brewer, Cathy; Schilero, Cathy; Smolenski, Kathy; McGraw, Mary; Denk, Barbara; Naska, Theresa; Laube, Frances; Steele, Ruth; Greene, Dale; Kastl, Alison; Bell, Susan; Aziz, Dina; Chiocca, E. A.; McPherson, Christopher; Warnick, Ronald; Barnett, Gene H.; Sloan, Andrew E.; Barnholtz-Sloan, Jill S.

2012-01-01

Purpose: Family history is associated with gliomas, but this association has not been established for benign brain tumors. Using information from newly diagnosed primary brain tumor patients, we describe patterns of family cancer histories in patients with benign brain tumors and compare those to patients with gliomas. Methods: Newly diagnosed primary brain tumor patients were identified as part of the Ohio Brain Tumor Study. Each patient was asked to participate in a telephone interview about personal medical history, family history of cancer, and other exposures. Information was available from 33 acoustic neuroma (65%), 78 meningioma (65%), 49 pituitary adenoma (73.1%), and 152 glioma patients (58.2%). The association between family history of cancer and each subtype was compared with gliomas using unconditional logistic regression models generating odds ratios (ORs) and 95% confidence intervals. Results: There was no significant difference in family history of cancer between patients with glioma and benign subtypes. Conclusion: The results suggest that benign brain tumor may have an association with family history of cancer. More studies are warranted to disentangle the potential genetic and/or environmental causes for these diseases. PMID:22649779

Prospectus

PubMed Central

Parsons, Peter A.

2009-01-01

Free living organisms typically occur in harsh environments challenged by abiotic stresses of varying intensities. Taking ionizing radiation and caloric restriction as examples, environmental variation from benign to extreme gives a fitness-stress continuum where energetic efficiency, a measure of fitness, is inversely related to stress level. Hormesis occurs in benign regions for these examples. In contrast aging emphasizes survival towards the limits of survival under accumulating stress from Reactive Oxygen Species, ROS. An energetic evolutionary approach underlies an ecological aging theory based principally upon survival, which incorporates hormesis. Multiple environmental agents contributing to hormesis should be considered by those attempting to improve the quality of life by delaying the onset of senescence, so enhancing survival. Caloric restriction has wider acceptance in this process than ionizing radiation. PMID:20221282

GYPCHEK biological insecticide for the gypsy moth

Treesearch

John D. Podgwaite

1999-01-01

With administrative and financial support from its State and Private Forestry division, the USDA Forest Service has directed much effort toward developing viral pesticides that kill forest insect pests. Most environmentally benign viral pesticides are narrow host-range products (Groner 1986) that are most useful in situations where environmental concerns are paramount...

Environmentally benign semiconductor processing for dielectric etch

NASA Astrophysics Data System (ADS)

Liao, Marci Yi-Ting

Semiconductor processing requires intensive usage of chemicals, electricity, and water. Such intensive resource usage leaves a large impact on the environment. For instance, in Silicon Valley, the semiconductor industry is responsible for 80% of the hazardous waste sites contaminated enough to require government assistance. Research on environmentally benign semiconductor processing is needed to reduce the environmental impact of the semiconductor industry. The focus of this dissertation is on the environmental impact of one aspect of semiconductor processing: patterning of dielectric materials. Plasma etching of silicon dioxide emits perfluorocarbons (PFCs) gases, like C2F6 and CF4, into the atmosphere. These gases are super global warming/greenhouse gases because of their extremely long atmospheric lifetimes and excellent infrared absorption properties. We developed the first inductively coupled plasma (ICP) abatement device for destroying PFCs downstream of a plasma etcher. Destruction efficiencies of 99% and 94% can be obtained for the above mentioned PFCs, by using O 2 as an additive gas. Our results have lead to extensive modeling in academia as well as commercialization of the ICP abatement system. Dielectric patterning of hi-k materials for future device technology brings different environment challenges. The uncertainty of the hi-k material selection and the patterning method need to be addressed. We have evaluated the environmental impact of three different dielectric patterning methods (plasma etch, wet etch and chemical-mechanical polishing), as well as, the transistor device performances associated with the patterning methods. Plasma etching was found to be the most environmentally benign patterning method, which also gives the best device performance. However, the environmental concern for plasma etching is the possibility of cross-contamination from low volatility etch by-products. Therefore, mass transfer in a plasma etcher for a promising hi-k dielectric material, ZrO2, was studied. A novel cross-contamination sampling technique was developed, along with a mass transfer model.

Ultraviolet Light Surface Treatment as an Environmentally Benign Process for Production, Maintenance and Repair of Military Composite Structures

NASA Astrophysics Data System (ADS)

Drzal, Lawrence T.

2002-02-01

The principal objective of this work is to develop a low-cost, high-speed, environmentally benign, dry surface treatment method for production, and repair of military composite structures using ultraviolet (UV) light in ambient air. The potential advantage of this method is that it would eliminate volatile organic wastes (VOCs), reduce or eliminate the use of solutions and detergents, and provide a robust surface that would enhance or eliminate the use of solutions and detergents, and provide a robust surface that would enhance the wetting and spreading of paints, coatings and adhesives on polymeric and inorganic surfaces treated by this method. A manufacturing base for UV production equipment is in place although not for this application. There is a need for development of an environmentally friendly, cost effective as well as a robust surface treatment method that can clean a surface as well as create a beneficial chemistry for painting and produce optimum adhesive bonding of polymers, polymer composites and metal surfaces. With this in mind, three main technical objectives were sought in the work. The first objective was to determine the usefulness of UV and UV/O(3) to surface treatments to clean and chemically modify the surface of typical PMCs used in DOD systems. The second objective was to determine the effectiveness of this surface preparation for production and/or repair of adhesively bonded, painted and/or coated polymer matrix composite structures. Finally, a determination of the environmental and performance benefits of this method as a new environmentally benign processing method for the production and/or re air of adhesively SERDP, SERDP collection, robust surface, polymeric surface, inorganic surface, volatile organic compounds (VOC) emissions.

Dynamic urea bond for the design of reversible and self-healing polymers

NASA Astrophysics Data System (ADS)

Ying, Hanze; Zhang, Yanfeng; Cheng, Jianjun

2014-02-01

Polymers bearing dynamic covalent bonds may exhibit dynamic properties, such as self-healing, shape memory and environmental adaptation. However, most dynamic covalent chemistries developed so far require either catalyst or change of environmental conditions to facilitate bond reversion and dynamic property change in bulk materials. Here we report the rational design of hindered urea bonds (urea with bulky substituent attached to its nitrogen) and the use of them to make polyureas and poly(urethane-urea)s capable of catalyst-free dynamic property change and autonomous repairing at low temperature. Given the simplicity of the hindered urea bond chemistry (reaction of a bulky amine with an isocyanate), incorporation of the catalyst-free dynamic covalent urea bonds to conventional polyurea or urea-containing polymers that typically have stable bulk properties may further broaden the scope of applications of these widely used materials.

Dynamic urea bond for the design of reversible and self-healing polymers

PubMed Central

Ying, Hanze; Zhang, Yanfeng; Cheng, Jianjun

2014-01-01

Polymers bearing dynamic covalent bonds may exhibit dynamic properties, such as self-healing, shape memory and environmental adaptation. However, most dynamic covalent chemistries developed so far require either catalyst or change of environmental conditions to facilitate bond reversion and dynamic property change in bulk materials. Here we report the rational design of hindered urea bonds (urea with bulky substituent attached to its nitrogen) and the use of them to make polyureas and poly(urethane-ureas) capable of catalyst-free dynamic property change and autonomous repairing at low temperature. Given the simplicity of the hindered urea bond chemistry (reaction of a bulky amine with an isocyanate), incorporation of the catalyst-free dynamic covalent urea bonds to conventional polyurea or urea-containing polymers that typically have stable bulk properties may further broaden the scope of applications of these widely used materials. PMID:24492620

Continuous flow room temperature reductive aqueous homo-coupling of aryl halides using supported Pd catalysts

PubMed Central

Feiz, Afsaneh; Bazgir, Ayoob; Balu, Alina M.; Luque, Rafael

2016-01-01

A convenient and environmentally friendly protocol for the preparation of biaryls at room temperature under continuous flow conditions is reported. A simple reductive homo-coupling Ullmann-type reaction was performed in an H-Cube mini using commercially available supported Pd catalysts under mild reaction conditions, with quantitative conversion to target products. Commercial Pd catalysts were found to be highly stable under the investigated reaction conditions, with a minimum Pd leaching into solution after several reaction runs (ca. 20 h on stream). PMID:27600989

CATALYST-FREE REACTIONS UNDER SOLVENT-FEE CONDITIONS: MICROWAVE-ASSISTED SYNTHESIS OF HETEROCYCLIC HYDRAZONES BELOW THE MELTING POINT OF NEAT REACTANTS

EPA Science Inventory

The reaction of neat 5- or 8-oxobenzopyran-2(1H)-ones with a variety of aromatic and heteroaromatic hydrazines are remarkable accelerated upon irradiation in a household microwave oven in the absence of any catalyst, solid support or solvent thus providing an environmentally frie...

An environmentally friendly organosolv (ethanol-water) pulping of poplar wood.

PubMed

Akgul, Mehmet; Kirci, Huseyin

2009-09-01

In this study pulp production from the fast growing plant, poplar; was examined for organosolv pulping with or without catalysts. In order to find the optimum cooking conditions, 18 different cooking experiments were carried out. The effect of ethanol ratio, cooking time as well as catalyst was studied. It was observed that even at lower temperature (90 degrees C), cooking without catalyst was able to cause sufficient defiberization. It was seen that the increasing proportion of catalyst and cooking temperature resulted in an increased delignification. However in the case of using 0.02% acid catalyst pulp yield and viscosity were lowered to an unacceptable level. The most important cooking factors were found to be the proportion of acid catalyst. Furthermore, the delignification performance was found to be depending on the pH of the black liquor. In a result, the optimum pulp properties were obtained by cooking at 180 degrees C for 90 min with 50% ethanol mixture without catalyst. The pulp yield was noted as 44.49%, viscosity was 892 cm2 g(-1) and the kappa number was 67.

Recycling of waste spent catalyst in road construction and masonry blocks.

PubMed

Taha, Ramzi; Al-Kamyani, Zahran; Al-Jabri, Khalifa; Baawain, Mahad; Al-Shamsi, Khalid

2012-08-30

Waste spent catalyst is generated in Oman as a result of the cracking process of petroleum oil in the Mina Al-Fahl and Sohar Refineries. The disposal of spent catalyst is of a major concern to oil refineries. Stabilized spent catalyst was evaluated for use in road construction as a whole replacement for crushed aggregates in the sub-base and base layers and as a partial replacement for Portland cement in masonry blocks manufacturing. Stabilization is necessary as the waste spent catalyst exists in a powder form and binders are needed to attain the necessary strength required to qualify its use in road construction. Raw spent catalyst was also blended with other virgin aggregates, as a sand or filler replacement, for use in road construction. Compaction, unconfined compressive strength and leaching tests were performed on the stabilized mixtures. For its use in masonry construction, blocks were tested for unconfined compressive strength at various curing periods. Results indicate that the spent catalyst has a promising potential for use in road construction and masonry blocks without causing any negative environmental impacts. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation and characterization of bi-metallic nanoparticle catalyst having better anti-coking properties using reverse micelle technique

NASA Astrophysics Data System (ADS)

Zacharia, Thomas

Energy needs are rising on an exponential basis. The mammoth energy sources like coal, natural gas and petroleum are the cause of pollution. The large outcry for an alternate energy source which is environmentally friendly and energy efficient is heard during the past few years. This is where “Clean-Fuel” like hydrogen gained its ground. Hydrogen is mainly produced by steam methane reforming (SMR). An alternate sustainable process which can reduce the cost as well as eliminate the waste products is Tri-reforming. In both these reforming processes nickel is used as catalyst. However as the process goes on the catalyst gets deactivated due to coking on the catalytic surface. This goal of this thesis work was to develop a bi-metallic catalyst which has better anti-coking properties compared to the conventional nickel catalyst. Tin was used to dope nickel. It was found that Ni3Sn complex around a core of Ni is coking resistant compared to pure nickel catalyst. Reverse micelle synthesis of catalyst preparation was used to control the size and shape of catalytic particles. These studies will benefit researches on hydrogen production and catalyst manufactures who work on different bi-metallic combinations.

Environmental education as a catalyst for behavior change: a study of the effects of Coastwatch Magazine on subscriber environmental knowledge and behavior

Treesearch

David Graefe; Hans Vogelsong

2008-01-01

Environmental degradation resulting from human habits and behaviors has become an increasingly important issue in contemporary society. One organization working to encourage coastal environmental sustainability is North Carolina Sea Grant, which publishes the educational magazine Coastwatch. It is NC Sea Grant's desire that coast-related...

Pt-Pd bimetallic nanoparticles on MWCNTs: catalyst for hydrogen peroxide electrosynthesis

NASA Astrophysics Data System (ADS)

Félix-Navarro, R. M.; Beltrán-Gastélum, M.; Salazar-Gastélum, M. I.; Silva-Carrillo, C.; Reynoso-Soto, E. A.; Pérez-Sicairos, S.; Lin, S. W.; Paraguay-Delgado, F.; Alonso-Núñez, G.

2013-08-01

Bimetallic nanoparticles of Pt-Pd were deposited by the microemulsion method on a multiwall carbon nanotube (MWCNTs) to obtain a Pt-Pd/MWCNTs for electrocatalytic reduction of O2 to H2O2. The activity and selectivity of the catalyst was determined qualitatively by the rotating disk electrode method in acidic medium. The catalyst was spray-coated onto a reticulated vitreous carbon substrate and quantitatively was tested in bulk electrolysis for 20 min under potentiostatic conditions (0.5 V vs Ag/AgCl) in a 0.5 M H2SO4 electrolyte using dissolved O2. The bulk electrolysis experiments show that the Pt-Pd/MWCNTs catalyst is more efficient for H2O2 electrogeneration than a MWCNTs catalyst. Nitrobenzene degradation by electrogenerated H2O2 alone and Electro-Fenton process were also tested. Our results show that both processes decompose nitrobenzene, but the Electro-Fenton process does it more efficiently. The prepared nanoparticulated catalyst shows a great potential in environmental applications.

GREEN CATALYZED OXIDATION OF HYDROCARBONS IN ALTERNATIVE SOLVENT SYSTEMS GENERATED BY PARIS II DECHEMA; GREEN SOLVENTS FOR CATALYSIS - ENVIRONMENTALLY BENIGN REACTION MEDIA

EPA Science Inventory

Green catalyzed oxidation of hydrocarbons in alternative solvent systems generated by PARIS II
Thomas M. Becker, Michael A. Gonzalez, Paul F. Harten; Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26 West Mar...

Hydrothermal Aging Effects on Fe/SSZ-13 and Fe/Beta NH3–SCR Catalysts

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

Gao, Feng; Szanyi, János; Wang, Yilin

Cu/SSZ-13 has been successfully commercialized as a diesel engine exhaust aftertreatment SCR catalyst in the past few years. This catalyst, however, displays undesirable NH3-SCR selectivity at elevated reaction temperature (≥ 350 C) after hydrothermal aging. Fe/zeolites, despite the fact that most of them degrade beyond tolerance after hydrothermal aging at temperatures ≥ 650 C, typically maintain good SCR selectivities. In recent years, Fe/beta has been identified as one of the more robust Fe/zeolites for use in NH3-SCR, where activity maintains even after hydrothermal aging at 750 C. Very recently, we, for the first time, synthesized and tested NH3-SCR performance formore » fresh and hydrothermally aged Fe/SSZ-13 catalysts. This study demonstrated that Fe/SSZ-13 is also a promising robust SCR catalyst, especially for high-temperature applications. In the present study, we compare catalytic performance between Fe/SSZ-13 and Fe/beta with similar Fe loadings and Si/Al ratios. Special attention is paid to effects from hydrothermal aging, aiming to understanding similarities and differences between these two catalysts. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Program for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less

Transformation of Active Sites in Fe/SSZ-13 SCR Catalysts during Hydrothermal Aging: A Spectroscopic, Microscopic, and Kinetics Study

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

Kovarik, Libor; Washton, Nancy M.; Kukkadapu, Ravi

Fe/SSZ-13 catalysts (Si/Al = 12, Fe loadings 0.37% and 1.20%) were prepared via solution ion-exchange, and hydrothermally aged at 600, 700 and 800 C. The fresh and aged catalysts were characterized with surface area/pore volume analysis, Mössbauer, solid-state MAS NMR, NO titration FTIR spectroscopies, and TEM and APT imaging. Hydrothermal aging causes dealumination of the catalysts, and transformation of various Fe sites. The latter include conversion of free Fe2+ ions to dimeric Fe(III) species, the agglomeration of isolated Fe-ions to Fe-oxide clusters, and incorporation of Al into the Fe-oxide species. These changes result in complex influences on standard SCR andmore » NO/NH3 oxidation reactions. In brief, mild aging causes catalyst performance enhancement for SCR, while harsh aging at 800 C deteriorates SCR performance. In comparison to Fe/zeolites more prone to hydrothermal degradation, this study demonstrates that via the utilization of highly hydrothermally stable Fe/SSZ-13 catalysts, more accurate correlations between various Fe species and their roles in SCR related chemistries can be made. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less

Recent Developments of Electrochemical Promotion of Catalysis in the Techniques of DeNOx

PubMed Central

Tang, Xiaolong; Yi, Honghong; Chen, Chen; Wang, Chuan

2013-01-01

Electrochemical promotion of catalysis reactions (EPOC) is one of the most significant discoveries in the field of catalytic and environmental protection. The work presented in this paper focuses on the aspects of reaction mechanism, influencing factors, and recent positive results. It has been shown with more than 80 different catalytic systems that the catalytic activity and selectivity of conductive catalysts deposited on solid electrolytes can be altered in the last 30 years. The active ingredient of catalyst can be activated by applying constant voltage or constant current to the catalysts/electrolyte interface. The effect of EPOC can improve greatly the conversion rate of NOx. And it can also improve the lifetime of catalyst by inhibiting its poisoning. PMID:23970835

Current advances and trends in electro-Fenton process using heterogeneous catalysts - A review.

PubMed

Poza-Nogueiras, Verónica; Rosales, Emilio; Pazos, Marta; Sanromán, M Ángeles

2018-06-01

Over the last decades, advanced oxidation processes have often been used alone, or combined with other techniques, for remediation of ground and surface water pollutants. The application of heterogeneous catalysis to electrochemical advanced oxidation processes is especially useful due to its efficiency and environmental safety. Among those processes, electro-Fenton stands out as the one in which heterogeneous catalysis has been broadly applied. Thus, this review has introduced an up-to-date collation of the current knowledge of the heterogeneous electro-Fenton process, highlighting recent advances in the use of different catalysts such as iron minerals (pyrite, magnetite or goethite), prepared catalysts by the load of metals in inorganic and organic materials, nanoparticles, and the inclusion of catalysts on the cathode. The effects of physical-chemical parameters as well as the mechanisms involved are critically assessed. Finally, although the utilization of this process to remediation of wastewater overwhelmingly outnumber other utilities, several applications have been described in the context of regeneration of adsorbent or the remediation of soils as clear examples of the feasibility of the electro-Fenton process to solve different environmental problems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Multiple benefits of alloparental care in a fluctuating environment.

PubMed

Guindre-Parker, Sarah; Rubenstein, Dustin R

2018-02-01

Although cooperatively breeding vertebrates occur disproportionately in unpredictable environments, the underlying mechanism shaping this biogeographic pattern remains unclear. Cooperative breeding may buffer against harsh conditions (hard life hypothesis), or additionally allow for sustained breeding under benign conditions (temporal variability hypothesis). To distinguish between the hard life and temporal variability hypotheses, we investigated whether the number of alloparents at a nest increased reproductive success or load-lightening in superb starlings ( Lamprotornis superbus ), and whether these two types of benefits varied in harsh and benign years. We found that mothers experienced both types of benefits consistent with the temporal variability hypothesis, as larger contingents of alloparents increased the number of young fledged while simultaneously allowing mothers to reduce their provisioning rates under both harsh and benign rainfall conditions. By contrast, fathers experienced load-lightening only under benign rainfall conditions, suggesting that cooperative breeding may serve to take advantage of unpredictable benign breeding seasons when they do occur. Cooperative breeding in unpredictable environments may thus promote flexibility in offspring care behaviour, which could mitigate variability in the cost of raising young. Our results highlight the importance of considering how offspring care decisions vary among breeding roles and across fluctuating environmental conditions.

Multiple benefits of alloparental care in a fluctuating environment

PubMed Central

2018-01-01

Although cooperatively breeding vertebrates occur disproportionately in unpredictable environments, the underlying mechanism shaping this biogeographic pattern remains unclear. Cooperative breeding may buffer against harsh conditions (hard life hypothesis), or additionally allow for sustained breeding under benign conditions (temporal variability hypothesis). To distinguish between the hard life and temporal variability hypotheses, we investigated whether the number of alloparents at a nest increased reproductive success or load-lightening in superb starlings (Lamprotornis superbus), and whether these two types of benefits varied in harsh and benign years. We found that mothers experienced both types of benefits consistent with the temporal variability hypothesis, as larger contingents of alloparents increased the number of young fledged while simultaneously allowing mothers to reduce their provisioning rates under both harsh and benign rainfall conditions. By contrast, fathers experienced load-lightening only under benign rainfall conditions, suggesting that cooperative breeding may serve to take advantage of unpredictable benign breeding seasons when they do occur. Cooperative breeding in unpredictable environments may thus promote flexibility in offspring care behaviour, which could mitigate variability in the cost of raising young. Our results highlight the importance of considering how offspring care decisions vary among breeding roles and across fluctuating environmental conditions. PMID:29515910

EDITORIAL: Ensuring sustainability with green nanotechnology Ensuring sustainability with green nanotechnology

NASA Astrophysics Data System (ADS)

Wong, Stanislaus; Karn, Barbara

2012-07-01

Nanotechnology offers immense promise for developing new technologies that are more sustainable than current technologies. All major industrial sectors have felt nanotechnology's impact, mainly from the incorporation of nanomaterials into their products. For example, nanotechnology has improved the design and performance of products in areas as diverse as electronics, medicine and medical devices, food and agriculture, cosmetics, chemicals, materials, coatings, energy, as well as many others. Moreover, the revenues from nanotechnology-enabled products are not trivial. For instance, Lux Research maintains that commercial sales in both Europe and the USA will attain revenues of over 1 trillion from nano-enabled products by 2015. The manufacturing of the nanomaterials for these products uses many processes equivalent to chemical manufacturing processes. As a result, manufacturing nanomaterials can produce either harmful pollutants or adverse environmental impacts similar to those from chemical manufacturing. Unlike the chemical industry, however, those same processes are not ingrained in the manufacturing of nanomaterials, and the opportunity exists at the initial design stage to purposely account for and mitigate out potentially harmful environmental impacts. While prevention has not been a priority in current industries, it can become a main concern for the new and future industries that manufacture nanomaterials on a bulk commercial scale. This is where green nanotechnology comes in. Green nanotechnology involves deliberate efforts aimed at developing meaningful and reasonable protocols for generating products and their associated production processes in a benign fashion. The goal is a conscious minimization of risks associated with the products of nanoscience. The green products of nanotechnology are those that are used in either direct or indirect environmental applications. Direct environmental applications provide benefits such as monitoring using nano-enabled sensors, remediation of hazardous waste sites with nanomaterials, or treatment of wastewater and drinking water with nanomaterials. Indirect environmental applications include, for example, the saved energy associated with either lighter nanocomposite materials in transport vehicles or reduced waste from smaller products. The production and process aspects of green nanotechnology involve both making nanomaterials in a more environmentally benign fashion and using nanomaterials to make current chemical processes more environmentally acceptable. Examples of producing nanomaterials in a 'greener manner' could involve but are not limited to the use of supercritical CO2, water, or ionic liquids to replace a volatile organic solvent. Either self-assembly or templating might also be used to eliminate waste in manufacturing. Renewables could be utilized as replacements for either nonrenewable and/or toxic starting materials. Microwave techniques might potentially help to conserve energy, as could both facile thermal and hydrothermal processes. Catalytic and photocatalytic reactions could also increase efficiency and decrease the formation of harmful byproducts. In addition, engineered nanomaterials themselves can be used as catalysts in current chemical processes and as separation membranes to aid in the efficiency of these operations. Furthermore, in order to be truly green, these products and processes must be considered within a lifecycle framework. The papers in this special issue are but a small sampling of the myriad of possibilities that green nanotechnology holds. In the nascent nanotechnology industry, green nanotechnology offers the opportunity to get it right in the first place. It is not too late to take Ben Franklin's words to heart, 'an ounce of prevention is worth a pound of cure'.

A Theoretical Study of Microwave Beam Absorption by a Rectenna

NASA Technical Reports Server (NTRS)

Ott, J. H.; Rice, J. S.; Thorn, D. C.

1981-01-01

The theoretical operational parameters for the workable satellite power system were examined. The system requirements for efficient transmission and reception of an environmentally benign microwave beam were determined.

Cultural Codes as Catalysts for Collective Conscientisation in Environmental Adult Education: Mr. Floatie, Tree Squatting and Save-Our-Surfers

ERIC Educational Resources Information Center

Walter, Pierre

2012-01-01

This study examines how cultural codes in environmental adult education can be used to "frame" collective identity, develop counterhegemonic ideologies, and catalyse "educative-activism" within social movements. Three diverse examples are discussed, spanning environmental movements in urban Victoria, British Columbia, Canada,…

ENVIRONMENTALLY FRIENDLIER ORGANIC TRANSFORMATIONS ON MINERAL SUPPORTS UNDER NON-TRADITIONAL CONDITIONS

EPA Science Inventory

Synthetic organic reactions performed under non-traditional conditions are gaining popularity primarily to circumvent the growing environmental concerns. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) either in presence of a catalyst o...

ENVIRONMENTALLY FRIENDLIER ORGANIC TRANSFORMATIONS ON MINERAL SUPPORTS UNDER NONTRADITIONAL CONDITIONS

EPA Science Inventory

Synthetic organic reactions performed under non-traditional conditions are gaining popularity primarily to circumvent the growing environmental concerns. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) either in presence of a catalyst o...

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

PubMed Central

Ramachandran, K.; Raj kumar, T.; Babu, K. Justice; Gnana kumar, G.

2016-01-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM−1 cm−2, low detection limit of 1.2 μM, a wide linear range from 5 μM–10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability. PMID:27833123

Oxidation driven ZnS Core-ZnO shell photocatalysts under controlled oxygen atmosphere for improved photocatalytic solar water splitting

NASA Astrophysics Data System (ADS)

Bak, Daegil; Kim, Jung Hyeun

2018-06-01

Zinc type photocatalysts attract great attentions in solar hydrogen production due to their easy availability and benign environmental characteristics. Spherical ZnS particles are synthesized with a facile hydrothermal method, and they are further used as core materials to introduce ZnO shell layer surrounding the core part by partial oxidation under controlled oxygen contents. The resulting ZnS core-ZnO shell photocatalysts represent the heterostructural type II band alignment. The existence of oxide layer also influences on proton adsorption power with an aid of strong base cites derived from highly electronegative oxygen atoms in ZnO shell layer. Photocatalytic water splitting reaction is performed to evaluate catalyst efficiency under standard one sun condition, and the highest hydrogen evolution rate (1665 μmolg-1h-1) is achieved from the sample oxidized at 16.2 kPa oxygen pressure. This highest hydrogen production rate is achieved in cooperation with increased light absorption and promoted charge separations. Photoluminescence analysis reveals that the improved visible light response is obtained after thermal oxidation process due to the oxygen vacancy states in the ZnO shell layer. Therefore, overall photocatalytic efficiency in solar hydrogen production is enhanced by improved charge separations, crystallinity, and visible light responses from the ZnS core-ZnO shell structures induced by thermal oxidation.

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

None

At the opening of the Symposium, Dr. Sharrah, Senior Vice President of Continental Oil Company, addressed the attendees, and his remarks are included in this volume. The Symposium was concluded by workshops which addressed specific topics. The topical titles are as follows: alcohol uses; production; environment and safety; and socio-economic. The workshops reflected a growing confidence among the attendees that the alcohols from coal, remote natural gas and biomass do offer alternatives to petroleum fuels. Further, they may, in the long run, prove to be equal or superior to the petroleum fuels when the aspects of performance, environment, health andmore » safety are combined with the renewable aspect of the biomass derived alcohols. Although considerable activity in the production and use of alcohols is now appearing in many parts of the world, the absence of strong, broad scale assessment and support for these fuels by the United States Federal Government was a noted point of concern by the attendees. The environmental consequence of using alcohols continues to be more benign in general than the petroleum based fuels. The exception is the family of aldehydes. Although the aldehydes are easily suppressed by catalysts, it is important to understand their production in the combustion process. Progress is being made in this regard. Of course, the goal is to burn the alcohols so cleanly that catalytic equipment can be eliminated. Separate abstracts are prepared for the Energy Data Base for individual presentations.« less

Organoelement chemistry: promising growth areas and challenges

NASA Astrophysics Data System (ADS)

Abakumov, G. A.; Piskunov, A. V.; Cherkasov, V. K.; Fedushkin, I. L.; Ananikov, V. P.; Eremin, D. B.; Gordeev, E. G.; Beletskaya, I. P.; Averin, A. D.; Bochkarev, M. N.; Trifonov, A. A.; Dzhemilev, U. M.; D'yakonov, V. A.; Egorov, M. P.; Vereshchagin, A. N.; Syroeshkin, M. A.; Jouikov, V. V.; Muzafarov, A. M.; Anisimov, A. A.; Arzumanyan, A. V.; Kononevich, Yu N.; Temnikov, M. N.; Sinyashin, O. G.; Budnikova, Yu H.; Burilov, A. R.; Karasik, A. A.; Mironov, V. F.; Storozhenko, P. A.; Shcherbakova, G. I.; Trofimov, B. A.; Amosova, S. V.; Gusarova, N. K.; Potapov, V. A.; Shur, V. B.; Burlakov, V. V.; Bogdanov, V. S.; Andreev, M. V.

2018-05-01

The chemistry of organoelement compounds is now one of the most rapidly developing fields of research, regarding both fundamental science and solution of applied problems. This review covers a variety of classes of organoelement compounds, ranging from molecules with highly labile carbon–element bonds to compounds with stable bonds that form the basis of novel structural materials and demonstrates their role in scientific research and industrial production. The use of Grignard reagents in modern organic synthesis and application of catalytic cyclomagnesiation and cycloalumination reactions for the preparation of difficult-to-access metallacycles are considered. The electron transfer processes in redox-active derivatives of Group 14 elements and the role of radical ions in these processes are discussed. Considerable attention is paid to organometallic compounds, first of all, as catalysts; the dynamic nature of catalysis with these compounds is noted. Unusual strained metallacycles of high thermal stability, zirconacyclocumulenes, which also exhibit catalytic activity, are described. Complexes with redox-active ligands that substantially affect the reactivity of the metal centre and directly participate in reactions with various substrates as well as organometallic compounds of lanthanides are considered. Modern environmentally benign methods for the synthesis of organosilicon compounds and production of unique materials based on them are discussed. Particular Sections are devoted to organophosphorus compounds, including those exhibiting therapeutic properties and possessing unusual optical characteristics, and organic chalcogen compounds, which find use as ligands and biologically active molecules. The bibliography includes 1045 references.

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

NASA Astrophysics Data System (ADS)

Ramachandran, K.; Raj Kumar, T.; Babu, K. Justice; Gnana Kumar, G.

2016-11-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM-1 cm-2, low detection limit of 1.2 μM, a wide linear range from 5 μM-10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.

Hydrogen Peroxide as a Sustainable Energy Carrier: Electrocatalytic Production of Hydrogen Peroxide and the Fuel Cell.

PubMed

Fukuzumi, Shunichi; Yamada, Yusuke; Karlin, Kenneth D

2012-11-01

This review describes homogeneous and heterogeneous catalytic reduction of dioxygen with metal complexes focusing on the catalytic two-electron reduction of dioxygen to produce hydrogen peroxide. Whether two-electron reduction of dioxygen to produce hydrogen peroxide or four-electron O 2 -reduction to produce water occurs depends on the types of metals and ligands that are utilized. Those factors controlling the two processes are discussed in terms of metal-oxygen intermediates involved in the catalysis. Metal complexes acting as catalysts for selective two-electron reduction of oxygen can be utilized as metal complex-modified electrodes in the electrocatalytic reduction to produce hydrogen peroxide. Hydrogen peroxide thus produced can be used as a fuel in a hydrogen peroxide fuel cell. A hydrogen peroxide fuel cell can be operated with a one-compartment structure without a membrane, which is certainly more promising for the development of low-cost fuel cells as compared with two compartment hydrogen fuel cells that require membranes. Hydrogen peroxide is regarded as an environmentally benign energy carrier because it can be produced by the electrocatalytic two-electron reduction of O 2 , which is abundant in air, using solar cells; the hydrogen peroxide thus produced could then be readily stored and then used as needed to generate electricity through the use of hydrogen peroxide fuel cells.

Hydroprocessing of Jatropha Oil for Production of Green Diesel over Non-sulfided Ni-PTA/Al2O3 Catalyst

PubMed Central

Liu, Jing; Lei, Jiandu; He, Jing; Deng, Lihong; Wang, Luying; Fan, Kai; Rong, Long

2015-01-01

The non-sulfided Ni-PTA/Al2O3 catalyst was developed to produce green diesel from the hydroprocessing of Jatropha oil. The Ni-PTA/Al2O3 catalyst was prepared by one-pot synthesis of Ni/Al2O3 with the co-precipitation method and then impregnanting Ni/Al2O3 with PTA solution. The catalysts were characterized with BET, SEM-EDX, TEM, XRD, XPS, TGA and NH3-TPD. The Ni and W species of the Ni-PTA/Al2O3 catalyst were much more homogeneously distributed on the surface than that of commercial Al2O3. Catalytic performance in the hydroprocessing of Jatropha oil was evaluated by GC. The maximum conversion of Jatropha oil (98.5 wt%) and selectivity of the C15-C18 alkanes fraction (84.5 wt %) occurred at 360 °C, 3.0 MPa, 0.8 h−1. The non-sulfided Ni-PTA/Al2O3 catalyst is more environmentally friendly than the conventional sulfided hydroprocessing catalyst, and it exhibited the highest catalytic activity than the Ni-PTA catalyst supported with commercial Al2O3 grain and Al2O3 powder. PMID:26162092

Nature-driven photochemistry for catalytic solar hydrogen production: a Photosystem I-transition metal catalyst hybrid.

PubMed

Utschig, Lisa M; Silver, Sunshine C; Mulfort, Karen L; Tiede, David M

2011-10-19

Solar energy conversion of water into the environmentally clean fuel hydrogen offers one of the best long-term solutions for meeting future energy demands. Nature provides highly evolved, finely tuned molecular machinery for solar energy conversion that exquisitely manages photon capture and conversion processes to drive oxygenic water-splitting and carbon fixation. Herein, we use one of Nature's specialized energy-converters, the Photosystem I (PSI) protein, to drive hydrogen production from a synthetic molecular catalyst comprised of inexpensive, earth-abundant materials. PSI and a cobaloxime catalyst self-assemble, and the resultant complex rapidly produces hydrogen in aqueous solution upon exposure to visible light. This work establishes a strategy for enhancing photosynthetic efficiency for solar fuel production by augmenting natural photosynthetic systems with synthetically tunable abiotic catalysts.

ENVIRONMENTAL BENIGN MITIGATION OF MICROBIOLOGICALLY INFLUENCED CORROSION (MIC)

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

J.R. Paterek; G. Husmillo; V. Trbovic

The overall program objective is to develop and evaluate environmental benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is one or more environmental benign, a.k.a. ''green'' products that can be applied to maintain the structure and dependability of the natural gas infrastructure. The technical approach for this quarter were isolation and cultivation of MIC-causing microorganisms from corroded pipeline samples, optimizing parameters in the laboratory-scale corrosion test loop system and testing the effective concentrations of Capsicum sp. extracts to verifymore » the extent of corrosion on metal coupons by batch culture method. A total of 22 strains from the group of heterotrophic, acid producing, denitrifying and sulfate reducing bacteria were isolated from the gas pipeline samples obtained from Northern Indiana Public Service Company in Trenton, Indiana. They were purified and will be sent out for identification. Bacterial strains of interest were used in antimicrobial screenings and test loop experiments. Parameters for the laboratory-scale test loop system such as gas and culture medium flow rate; temperature; inoculation period; and length of incubation were established. Batch culture corrosion study against Desulfovibrio vulgaris showed that one (S{sub 1}M) out of the four Capsicum sp. extracts tested was effective in controlling the corrosion rate in metal coupons by 33.33% when compared to the untreated group.« less

Strategies for improving the performance and stability of Ni-based catalysts for reforming reactions.

PubMed

Li, Shuirong; Gong, Jinlong

2014-11-07

Owing to the considerable publicity that has been given to petroleum related economic, environmental, and political problems, renewed attention has been focused on the development of highly efficient and stable catalytic materials for the production of chemical/fuel from renewable resources. Supported nickel nanoclusters are widely used for catalytic reforming reactions, which are key processes for generating synthetic gas and/or hydrogen. New challenges were brought out by the extension of feedstock from hydrocarbons to oxygenates derivable from biomass, which could minimize the environmental impact of carbonaceous fuels and allow a smooth transition from fossil fuels to a sustainable energy economy. This tutorial review describes the recent efforts made toward the development of nickel-based catalysts for the production of hydrogen from oxygenated hydrocarbons via steam reforming reactions. In general, three challenges facing the design of Ni catalysts should be addressed. Nickel nanoclusters are apt to sinter under catalytic reforming conditions of high temperatures and in the presence of steam. Severe carbon deposition could also be observed on the catalyst if the surface carbon species adsorbed on metal surface are not removed in time. Additionally, the production of hydrogen rich gas with a low concentration of CO is a challenge using nickel catalysts, which are not so active in the water gas shift reaction. Accordingly, three strategies were presented to address these challenges. First, the methodologies for the preparation of highly dispersed nickel catalysts with strong metal-support interaction were discussed. A second approach-the promotion in the mobility of the surface oxygen-is favored for the yield of desired products while promoting the removal of surface carbon deposition. Finally, the process intensification via the in situ absorption of CO2 could produce a hydrogen rich gas with low CO concentration. These approaches could also guide the design of other types of heterogeneous base-metal catalysts for high temperature processes including methanation, dry reforming, and hydrocarbon combustion.

Surface profile control of FeNiPt/Pt core/shell nanowires for oxygen reduction reaction

DOE PAGES

Zhu, Huiyuan; Zhang, Sen; Su, Dong; ...

2015-03-18

The ever-increasing energy demand requires renewable energy schemes with low environmental impacts. Electrochemical energy conversion devices, such as fuel cells, combine fuel oxidization and oxygen reduction reactions and have been studied extensively for renewable energy applications. However, their energy conversion efficiency is often limited by kinetically sluggish chemical conversion reactions, especially oxygen reduction reaction (ORR). [1-5] To date, extensive efforts have been put into developing efficient ORR catalysts with controls on catalyst sizes, compositions, shapes and structures. [6-12] Recently, Pt-based catalysts with core/shell and one-dimensional nanowire (NW) morphologies were found to be promising to further enhance ORR catalysis.more » With the core/shell structure, the ORR catalysis of a nanoparticle (NP) catalyst can be tuned by both electronic and geometric effects at the core/shell interface. [10,13,14] With the NW structure, the catalyst interaction with the conductive support can be enhanced to facilitate electron transfer between the support and the NW catalyst and to promote ORR. [11,15,16]« less

Catalytic Efficiency of Titanium Dioxide (TiO2) and Zeolite ZSM-5 Catalysts in the in-situ Epoxidation of Palm Olein

NASA Astrophysics Data System (ADS)

Yunus, M. Z. Mohd; Jamaludin, S. K.; Abd. Karim, S. F.; Gani, A. Abd; Sauki, A.

2018-05-01

Titanium dioxide and zeolite ZSM-5 are the commonly used heterogeneous catalysts in many chemical reactions. They have several advantages such as low cost and environmental friendly. In this study, titanium dioxide and zeolite ZSM-5 act as catalyst in the in-situ epoxidation of palm olein. Epoxidation of palm olein was carried out by using in-situ generated performic acid to produce epoxidized palm olein in a semi-batch reactor at different temperatures (45°C and 60°C) and agitation speed of 400 rpm. The effects of both catalysts are studied to compare their efficiency in catalyzing the in-situ epoxidation. Epoxidized palm olein was analyzed by using percent of relative conversion to oxirane (RCO%) and fourier transform infrared spectroscopy (FTIR). Surface area of the catalysts used were then characterized by using BET. The results indicated that titanium dioxide is a better catalyst in the in-situ epoxidation of palm olein since it provides higher RCO% compared to Zeolite ZSM-5 at 45°C.

pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

NASA Astrophysics Data System (ADS)

Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

2014-05-01

The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (< 0.5 mg.kg-1, < 0.1 mg.kg-1, respectively). To evaluate leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

Evaluation of malt spent rootlets biochar as catalyst for biodiesel production.

NASA Astrophysics Data System (ADS)

Pantiora, Dimitra

2014-05-01

Evaluation of malt spent rootlets biochar as catalyst for biodiesel production. Dimitra Pantiora1, Hrissi K. Karapanagioti1, Ioannis D. Manariotis2, Alexis Lycourghiotis1, Christos Kordulis1,3 (1) University of Patras, Department of Chemistry, GR 26500, Patras, Greece, (2) University of Patras, Department of Civil Engineering, Patras, Greece, (3) Institute of Chemical Engineering Science (FORTH/ ICE-HT), Stadiou Str., Platani, GR 26500, Patras, Greece Biodiesel is an attractive renewable fuel, environmentally friendly, and can readily be synthesized from the triglycerides found in animal fats and vegetable oils. It can be used in existing engines. Biodiesel consists of fatty acid alkyl esters. Conversion of triglycerides to biodiesel fuel is commonly achieved through a series of transesterification reactions involving the reaction of an alkoxy group of an ester (i.e., mono-, di-, or triglyceride) with that of a small alcohol (usually methanol). This reaction is traditionally catalyzed by homogeneous catalysts, such as bases or mineral acids. Basic catalysts have been proved to be much more active than acidic ones. However, due to environmental (waste water) and economic concerns (catalyst separation and product and by-product cleaning), heterogeneous catalysts are much more desirable. In the present study we have evaluated the use of biochar, produced from malt spent rootlets, as a potential basic catalyst, for transesterification of triglycerides using triacetin as a probe molecule. The biochar used in this study was prepared by heating malt spent rootlets in an oxygen-limited environment. It is a carbon rich material, containing 66% C, 22% O, 0.45% Mg, 0.86% Si, 5.7% K, 1.5% Cl, 0.61% Ca, and 2.4% P. Aqueous suspension of this material equilibrates at pH= 10. This is probably due to high K content. Furthermore, it exhibits high specific surface area (SSA= 183 m2g-1). The above described characteristics make this material very promising catalyst for transesterification reactions. Indeed, the corresponding catalytic tests showed that 100% transesterification of triacetin can be achieved into 0.5 hour. This activity was maintained at least for 4 successive catalytic runs.

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

MacDonald, R.; Kelley, D.E.

In 1998, when Sunlaw Energy Corporation needed to retrofit their two natural gas fired power plants to meet new emissions requirements that were soon to come into place, they looked at existing technologies and found them either economically or environmentally undesirable. With the help of General Electric they developed a program of water injection that was capable of reducing the NO{sub x} emissions to 25 ppm. This, however, was not low enough to meet coming regulations. Sunlaw concluded that the best option for pollution control was to invert their own system. A partnership was formed between Sunlaw and Advanced Catalystmore » Systems, a catalyst development and manufacturing firm. The result of their efforts was Goal Line Environmental Technologies and the SCONOx catalytic absorption system. The newest SCONOx system, commissioned at Sunlaw's Federal cogeneration plant in December 1996, treats the exhaust of a GELM2500 gas turbine. Combined with water injection, it has reduced NO{sub x} emission from 160 ppm down to 1--2 ppm. Carbon monoxide emissions are virtually eliminated, with stack readings less than ambient levels. The SCONOx system uses single catalyst for both CO and NO{sub x} control. It oxidizes CO to CO{sub 2} and NO to NO{sub 2}, and the NO{sub 2} is then absorbed onto the surface of the catalyst. Just as a sponge absorbs water and must be periodically regenerated, the catalyst must be regenerated. This is accomplished by passing a dilute hydrogen gas across the surface of the catalyst in the absence of oxygen. Nitrogen oxygen are broken down into nitrogen and water, and this is exhausted up the stack instead of NO{sub x}. The SCONOx system is a breakthrough in CO and NO{sub x} control technology that makes it possible to have clean air without the use of ammonia or other hazardous materials. It is truly an environmentally friendly NO{sub x} system.« less

Systematic procedure for designing processes with multiple environmental objectives.

PubMed

Kim, Ki-Joo; Smith, Raymond L

2005-04-01

Evaluation of multiple objectives is very important in designing environmentally benign processes. It requires a systematic procedure for solving multiobjective decision-making problems due to the complex nature of the problems, the need for complex assessments, and the complicated analysis of multidimensional results. In this paper, a novel systematic procedure is presented for designing processes with multiple environmental objectives. This procedure has four steps: initialization, screening, evaluation, and visualization. The first two steps are used for systematic problem formulation based on mass and energy estimation and order of magnitude analysis. In the third step, an efficient parallel multiobjective steady-state genetic algorithm is applied to design environmentally benign and economically viable processes and to provide more accurate and uniform Pareto optimal solutions. In the last step a new visualization technique for illustrating multiple objectives and their design parameters on the same diagram is developed. Through these integrated steps the decision-maker can easily determine design alternatives with respect to his or her preferences. Most importantly, this technique is independent of the number of objectives and design parameters. As a case study, acetic acid recovery from aqueous waste mixtures is investigated by minimizing eight potential environmental impacts and maximizing total profit. After applying the systematic procedure, the most preferred design alternatives and their design parameters are easily identified.

Comparison of performance of wood extractives as preservatives in field tests against termites and decay in the USA and Pakistan

Treesearch

Babar Hassan; Sohail Ahmed; Mark Mankowski; Grant Kirker

2017-01-01

Increasing environmental regulations have limited the use of certain broad spectrum synthetic pesticides as wood preservatives creating a need for more environmentally benign wood preservative systems. Biocidal compounds from natural products have been proposed as alternatives to commercial wood preservatives, but field data from long term performance testing is...

Decomposition of environmentally persistent perfluorooctanoic acid in water by photochemical approaches.

PubMed

Hori, Hisao; Hayakawa, Etsuko; Einaga, Hisahiro; Kutsuna, Shuzo; Koike, Kazuhide; Ibusuki, Takashi; Kiatagawa, Hiroshi; Arakawa, Ryuichi

2004-11-15

The decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water by UV-visible light irradiation, by H202 with UV-visible light irradiation, and by a tungstic heteropolyacid photocatalyst was examined to develop a technique to counteract stationary sources of PFOA. Direct photolysis proceeded slowly to produce CO2, F-, and short-chain perfluorocarboxylic acids. Compared to the direct photolysis, H2O2 was less effective in PFOA decomposition. On the other hand, the heteropolyacid photocatalyst led to efficient PFOA decomposition and the production of F- ions and CO2. The photocatalyst also suppressed the accumulation of short-chain perfluorocarboxylic acids in the reaction solution. PFOA in the concentrations of 0.34-3.35 mM, typical of those in wastewaters after an emulsifying process in fluoropolymer manufacture, was completely decomposed by the catalyst within 24 h of irradiation from a 200-W xenon-mercury lamp, with no accompanying catalyst degradation, permitting the catalyst to be reused in consecutive runs. Gas chromatography/mass spectrometry (GC/MS) measurements showed no trace of environmentally undesirable species such as CF4, which has a very high global-warming potential. When the (initial PFOA)/(initial catalyst) molar ratio was 10: 1, the turnover number for PFOA decomposition reached 4.33 over 24 h of irradiation.

Revealing the Dynamics of Platinum Nanoparticle Catalysts on Carbon in Oxygen and Water Using Environmental TEM

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

Luo, Langli; Engelhard, Mark H.; Shao, Yuyan

Deactivation of supported metal nanoparticle catalysts, especially in relevant gas condition, is a critical challenge for many technological applications, including heterogeneous catalysis, electrocatalysis, fuel cells, biomedical imaging and drug delivery. It has been far more commonly realized that deactivation of catalysts stems from surface area loss due to particle coarsening, however, for which the mechanism remains largely unclear. Herein, we use aberration corrected environmental transmission electron microscopy, at atomic level, to in-situ observe the dynamics of Pt catalyst in fuel cell relevant gas conditions. Particles migration and coalescence is observed to be the dominant coarsening process. As compared with themore » case of H2O, O2 promotes Pt nanoparticle migration on carbon surface. Surprisingly, coating Pt/carbon with a nanofilm of electrolyte (Nafion ionomer) leads to a faster migration of Pt in H2O than in O2, a consequence of Nafion-carbon interface water “lubrication” effect. Atomically, the particles coalescence is featured by re-orientation of particles towards lattice matching, a process driven by orientation dependent van der Waals force. These results provide direct observations of dynamics of metal nanoparticles at critical surface/interface under relevant conditions and yield significant insights into the multi-phase interaction in related technological processes.« less

Radiation absorption and optimization of solar photocatalytic reactors for environmental applications.

PubMed

Colina-Márquez, Jose; Machuca-Martínez, Fiderman; Li Puma, Gianluca

2010-07-01

This study provides a systematic and quantitative approach to the analysis and optimization of solar photocatalytic reactors utilized in environmental applications such as pollutant remediation and conversion of biomass (waste) to hydrogen. Ray tracing technique was coupled with the six-flux absorption scattering model (SFM) to analyze the complex radiation field in solar compound parabolic collectors (CPC) and tubular photoreactors. The absorption of solar radiation represented by the spatial distribution of the local volumetric rate of photon absorption (LVRPA) depends strongly on catalyst loading and geometry. The total radiation absorbed in the reactors, the volumetric rate of absorption (VRPA), was analyzed as a function of the optical properties (scattering albedo) of the photocatalyst. The VRPA reached maxima at specific catalyst concentrations in close agreement with literature experimental studies. The CPC has on average 70% higher photon absorption efficiency than a tubular reactor and requires 39% less catalyst to operate under optimum conditions. The "apparent optical thickness" is proposed as a new dimensionless parameter for optimization of CPC and tubular reactors. It removes the dependence of the optimum catalyst concentration on tube diameter and photocatalyst scattering albedo. For titanium dioxide (TiO(2)) Degussa P25, maximum photon absorption occurs at apparent optical thicknesses of 7.78 for CPC and 12.97 for tubular reactors.

Life cycle assessment of gas atomised sponge nickel for use in alkaline hydrogen fuel cell applications

NASA Astrophysics Data System (ADS)

Wilson, Benjamin P.; Lavery, Nicholas P.; Jarvis, David J.; Anttila, Tomi; Rantanen, Jyri; Brown, Stephen G. R.; Adkins, Nicholas J.

2013-12-01

This paper presents a cradle-to-grave comparative Life Cycle Assessment (LCA) of new gas atomised (GA) sponge nickel catalysts and evaluates their performance against the both cast and crush (CC) sponge nickel and platinum standards currently used in commercial alkaline fuel cells (AFC). The LCA takes into account the energy used and emissions throughout the entire life cycle of sponge nickel catalysts - ranging from the upstream production of materials (mainly aluminium and nickel), to the manufacturing, to the operation and finally to the recycling and disposal. Through this assessment it was found that the energy and emissions during the operational phase associated with a given catalyst considerably outweigh the primary production, manufacturing and recycling. Primary production of the nickel (and to a lesser extent dopant materials) also has a significant environmental impact but this is offset by operational energy savings over the electrode's estimated lifetime and end of life recyclability. From the results it can be concluded that higher activity spongy nickel catalysts produced by gas atomisation could have a significantly lower environmental impact than either CC nickel or platinum. Doped GA sponge nickel in particular showed comparable performance to that of the standard platinum electrode used in AFCs.

In situ study of single-walled carbon nanotube growth in an environmental scanning electron microscope.

PubMed

Mehedi, H-A; Ravaux, J; Tahir, S; Podor, R; Jourdain, V

2016-12-16

Monitoring individual single-walled carbon nanotubes (SWCNTs) during their growth is a highly sought-after goal in view of understanding the processes involved in the nucleation, elongation and termination which ultimately control the diameter and chiral selectivity. Here, we report on the first truly in situ observations of SWCNT growth in an environmental scanning electron microscope (ESEM). The CNT growth from lithographically patterned catalysts was investigated as a function of the catalyst type (Fe, Co or Ni), temperature, type of precursor (ethanol or acetylene), gas phase composition and pressure, and pretreatment conditions, and we report on the most appropriate conditions for SWCNT growth in ESEM conditions. We show that this approach allows the observation at the submicron scale of the different steps of the nanotube synthesis including the catalyst reduction, the growth and percolation of the nanotube network, and the deposition of individual nanotubes grown in the gas phase on the substrate. Despite these obvious advantages, we identified a few limitations which will need to be tackled for fully taking advantage of the approach, for instance for monitoring the growth of individual SWCNTs by ESEM, including the short lifetime of the catalyst nanoparticles, the preference for kite growth (by opposition to surface growth) and the influence of the electron beam on the nanotube growth.

Chemical Strips Anodic Film From Aluminum

NASA Technical Reports Server (NTRS)

Eichinger, Eric C.

1993-01-01

Phosphoric acid solution offers advantages over other stripping solutions. More effective than other strippers and safer to use. Relatively environmentally benign, phosphoric acid stripper ceases its chemical attack so less process control is needed in its use.

Optimization of esterification of dicarboxylic acids and 2-ethyl-1-hexanol

NASA Astrophysics Data System (ADS)

Jafri, Nur Hafifah Nahdirah; Othman, Nor Hamidah Abu; Salimon, Jumat

2018-04-01

Dicarboxylate ester has the potential alternative as plasticizer which environmentally friendly in polymeric formulation especially for poly (vinyl chloride) (PVC). Dicarboxylate ester compounds were synthesized via esterification between dicarboxylic acid and 2-ethyl-1-hexanol by using sulfuric acid as catalyst. The effects of reaction parameters were studied by optimizing temperature, mole ratio of reactants, amount of catalyst and reaction to obtain highest ester conversion. The optimum results showed dicarboxylic acid successfully converted to the dicarboxylate ester at parameters; 4 hours; 120 °C; catalyst amount: 2% w/w of diacid; and mole ratio: 1:2.5. Functional group analysis was conducted by using ATR-FTIR spectroscopy.

Differential evolution of asexual and sexual females in a benign culture environment

PubMed Central

Snell, Terry W.

2013-01-01

Here we report one of the first investigations of evolvability of lifespan and reproduction in metazoans, examining both extrinsic and intrinsic factors. We tested effects on senescence of an environmental variable (simulated lake hydroperiod, the length of time an aquatic habitat is inundated), female reproductive physiology (asexual females that reproduce by ameiosis, versus sexual females reproducing by meiosis), and time in a benign culture environment (minimal, if any, external mortality factors). To do this we established chemostat cultures of the rotifer Brachionus plicatilis s.s., and maintained the cultures for 385 d. Hydroperiod alone or in interaction with the effects of time in the benign environment (season) or reproductive physiology had no significant effect on the net reproductive rate, generation time, or rate of aging. Yet combining animals from both ephemeral and permanent hydroperiods revealed a 26% increase in asexual female lifespan across seasons (23% decrease in the rate of aging) and a 56% increase in asexual fecundity, suggesting that maintenance in benign laboratory conditions leads to slower aging. The relative stasis of traits for sexual females implies an impact of reproductive physiology on evolvability. In addition we found a positive correlation between fecundity and lifespan, suggesting an absence of trade-offs in life history traits in the benign laboratory environment. PMID:24795527

Process intensification of biodiesel production by using microwave and ionic liquids as catalyst

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

Handayani, Prima Astuti; Chemical Engineering Program, Faculty of Engineering, Semarang State University; Abdullah

The energy crisis pushes the development and intensification of biodiesel production process. Biodiesel is produced by transesterification of vegetable oils or animal fats and conventionally produced by using acid/base catalyst. However, the conventional method requires longer processing time and obtains lower yield of biodiesel. The microwave has been intensively used to accelerate production process and ionic liquids has been introduced as source of catalyst. This paper discusses the overview of the development of biodiesel production through innovation using microwave irradiation and ionic liquids catalyst to increase the yield of biodiesel. The potential microwave to reduce the processing time will bemore » discussed and compared with other energy power, while the ionic liquids as a new generation of catalysts in the chemical industry will be also discussed for its use. The ionic liquids has potential to enhance the economic and environmental aspects because it has a low corrosion effect, can be recycled, and low waste form.« less

Deoxygenation of glycolaldehyde and furfural on Mo2C/Mo(100)

NASA Astrophysics Data System (ADS)

McManus, Jesse R.; Vohs, John M.

2014-12-01

The desire to produce fuels and chemicals in an energy conscious, environmentally sympathetic approach has motivated considerable research on the use of cellulosic biomass feedstocks. One of the major challenges facing the utilization of biomass is finding effective catalysts for the efficient and selective removal of oxygen from the highly-oxygenated, biomass-derived platform molecules. Herein, a study of the reaction pathways for the biomass-derived platform molecule furfural and biomass-derived sugar model compound glycolaldehyde provides insight into the mechanisms of hydrodeoxygenation (HDO) on a model molybdenum carbide catalyst, Mo2C/Mo(100). Using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS), it was found that the Mo2C/Mo(100) catalyst was active for selective deoxygenation of the aldehyde carbonyl by facilitating adsorption of the aldehyde in an η2(C,O) bonding configuration. Furthermore, the catalyst showed no appreciable activity for furanic ring hydrogenation, highlighting the promise of relatively inexpensive Mo2C catalysts for selective HDO chemistry.

A facile self-assembly approach to prepare palladium/carbon nanotubes catalyst for the electro-oxidation of ethanol

NASA Astrophysics Data System (ADS)

Wen, Cuilian; Zhang, Xinyuan; Wei, Ying; Zhang, Teng; Chen, Changxin

2018-02-01

A facile self-assembly approach is reported to prepare palladium/carbon nanotubes (Pd/CNTs) catalyst for the electro-oxidation of ethanol. In this method, the Pd-oleate/CNTs was decomposed into the Pd/CNTs at an optimal temperature of 195 °C in air, in which no inert gas is needed for the thermal decomposition process due to the low temperature used and the decomposed products are also environmental friendly. The prepared Pd/CNTs catalyst has a high metallic Pd0 content and the Pd particles in the catalyst are disperse, uniform-sized with an average size of ˜2.1 nm, and evenly distributed on the CNTs. By employing our strategy, the problems including the exfoliation of the metal particles from the CNTs and the aggregation of the metal particles can be solved. Comparing with the commercial Pd/C one, the prepared Pd/CNTs catalyst exhibits a much higher electrochemical activity and stability for the electro-oxidation of ethanol in the direct ethanol fuel cells.

Process intensification of biodiesel production by using microwave and ionic liquids as catalyst

NASA Astrophysics Data System (ADS)

Handayani, Prima Astuti; Abdullah, dan Hadiyanto

2015-12-01

The energy crisis pushes the development and intensification of biodiesel production process. Biodiesel is produced by transesterification of vegetable oils or animal fats and conventionally produced by using acid/base catalyst. However, the conventional method requires longer processing time and obtains lower yield of biodiesel. The microwave has been intensively used to accelerate production process and ionic liquids has been introduced as source of catalyst. This paper discusses the overview of the development of biodiesel production through innovation using microwave irradiation and ionic liquids catalyst to increase the yield of biodiesel. The potential microwave to reduce the processing time will be discussed and compared with other energy power, while the ionic liquids as a new generation of catalysts in the chemical industry will be also discussed for its use. The ionic liquids has potential to enhance the economic and environmental aspects because it has a low corrosion effect, can be recycled, and low waste form.

Green synthesis of the Cu/Fe3O4 nanoparticles using Morinda morindoides leaf aqueous extract: A highly efficient magnetically separable catalyst for the reduction of organic dyes in aqueous medium at room temperature

NASA Astrophysics Data System (ADS)

Nasrollahzadeh, Mahmoud; Atarod, Monireh; Sajadi, S. Mohammad

2016-02-01

This paper reports the green and in-situ preparation of the Cu/Fe3O4 magnetic nanocatalyst synthesized using Morinda morindoides leaf extract without stabilizers or surfactants. The catalyst was characterized by XRD, SEM, EDS, UV-visible, TEM, VSM and TGA-DTA. The catalytic performance of the resulting nanocatalyst was examined for the reduction of 4-nitrophenol (4-NP), Congo red (CR) and Rhodamine B (RhB) in an environmental friendly medium at room temperature. The catalyst was recovered using an external magnet and reused several times without appreciable loss of its catalytic activity. In addition, the stability of the recycled catalyst has been proved by SEM and EDS techniques.

Direct evidence of atomic-scale structural fluctuations in catalyst nanoparticles.

PubMed

Lin, Pin Ann; Gomez-Ballesteros, Jose L; Burgos, Juan C; Balbuena, Perla B; Natarajan, Bharath; Sharma, Renu

2017-05-01

Rational catalyst design requires an atomic scale mechanistic understanding of the chemical pathways involved in the catalytic process. A heterogeneous catalyst typically works by adsorbing reactants onto its surface, where the energies for specific bonds to dissociate and/or combine with other species (to form desired intermediate or final products) are lower. Here, using the catalytic growth of single-walled carbon nanotubes (SWCNTs) as a prototype reaction, we show that the chemical pathway may in-fact involve the entire catalyst particle, and can proceed via the fluctuations in the formation and decomposition of metastable phases in the particle interior. We record in situ and at atomic resolution, the dynamic phase transformations occurring in a Cobalt catalyst nanoparticle during SWCNT growth, using a state-of-the-art environmental transmission electron microscope (ETEM). The fluctuations in catalyst carbon content are quantified by the automated, atomic-scale structural analysis of the time-resolved ETEM images and correlated with the SWCNT growth rate. We find the fluctuations in the carbon concentration in the catalyst nanoparticle and the fluctuations in nanotube growth rates to be of complementary character. These findings are successfully explained by reactive molecular dynamics (RMD) simulations that track the spatial and temporal evolution of the distribution of carbon atoms within and on the surface of the catalyst particle. We anticipate that our approach combining real-time, atomic-resolution image analysis and molecular dynamics simulations will facilitate catalyst design, improving reaction efficiencies and selectivity towards the growth of desired structure.

Investigating catalyst coated membrane equilibration time for polymer electrolyte membrane fuel cell manufacturing

NASA Astrophysics Data System (ADS)

Cote, Philippe

Mercedes-Benz Canada Inc., Fuel Cell Division, manufactures polymer electrolyte membrane fuel cell stacks for use in vehicles. The manufacturing line is being optimized for efficiency and quality control, in order to uphold the high standards of Mercedes-Benz Inc. vehicles. In an operating polymer electrolyte membrane fuel cell, the catalyst coated membrane facilitates the electrochemical reaction that generates electricity. This research examines the equilibration of catalyst coated membrane rolls to controlled temperature and humidity conditions, before they are used in the manufacturing of polymer electrolyte membrane fuel cells. Equilibration involves allowing the water content in the catalyst coated membrane to stabilize at the controlled conditions, in order to reduce mechanical stress in the material for better manufacturability. Initial equilibration measurements were conducted on discrete catalyst coated membrane samples using novel electronic conductivity measurements of the catalyst layer, and compared to ionic conductivity measurements of the membrane. Electronic conductivity measurements are easier to implement in the manufacturing environment than the more complex ionic conductivity measurements. When testing discrete catalyst coated membrane samples in an environmental chamber, the equilibration trends for the measured ionic and electronic conductivity signals were similar enough to permit us to adapt the electronic conductivity measurements for catalyst coated membrane in roll form. Equilibration measurements of catalyst coated membrane rolls were optimized to achieve a robust and repeatable procedure which could be used in the manufacturing environment at Mercedes-Benz Canada Inc., Fuel Cell Division.

Hydrogen production by ethanol steam reforming on Ni/oxide catalysts

NASA Astrophysics Data System (ADS)

Lazar, Mihaela D.; Dan, Monica; Mihet, Maria; Borodi, George; Almasan, Valer

2012-02-01

Hydrogen production from bio-fuels such as bio-ethanol provides significant environmental benefits since the resulted CO2 is consumed again for biomass growth, offering a carbon dioxide neutral energy source. In the actual conditions of increasing energy demand and atmosphere pollution, clean produced hydrogen can be an alternative option for a clean energy vector. In this paper we present the results obtained in hydrogen production by steam reforming of ethanol using oxide supported nickel catalysts. Although Ni is not the most active catalyst for this process, economically is the most attractive one, due to the high price and low availability of noble metals. Ni was dispersed on several oxides: ZrO2, Al2O3, Cr2O3, SiO2 with a target metal concentration of 8 wt%. using impregnation method. The catalysts were characterized using several techniques: N2 adsorption desorption isotherms to determine total surface area and porosity, XRD to determine oxide crystallinity and Ni crystallite size. Each catalyst was tested in steam reforming of ethanol at temperatures ranging from 150 to 350°C, at atmospheric pressure and a ethanol: steam ratio of 1:9. The best ethanol conversion and catalyst stability was obtained for Ni/Al2O3. The catalyst selectivity for H2 production depends on the support nature. The best H2 selectivity was obtained for Ni/ZrO2 catalyst.

Co-Liquefaction of Elbistan Lignite with Manure Biomass; Part 1. Effect of Catalyst Concentration

NASA Astrophysics Data System (ADS)

Koyunoglu, Cemil; Karaca, Hüseyin

2017-12-01

The hydrogenation of coal by molecular hydrogen has not been appreciable unless a catalyst has been used, especially at temperatures below 500 °C. Conversion under these conditions is essentially the result of the pyrolysis of coal, although hydrogen increases the yield of conversion due to the stabilization of radicals and other reactive species. Curtis and his co-workers has shown that highly effective and accessible catalyst are required to achieve high levels of oil production from the coprocessing of coal and heavy residua. In their work, powdered hydrotreating catalyst at high loadings an oil-soluble metal salts of organic acids as catalyst precursors achieved the highest levels of activity for coal conversion and oil production. Red mud which is iron-based catalysed has been used in several co-processing studies. It was used as an inexpensive sulphur sink for the H2S evolved to convert Fe into pyrrohotite during coal liquefaction. In this study, Elbistan Lignite (EL) processed with manure using red mud as a catalyst with the range of concentration from 3% to 12%. The main point of using red mud catalyst is to enhance oil products yield of coal liquefaction, which deals with its catalytic activity. On the other hand, red mud acts on EL liquefaction with manure as a catalyst and represents an environmental option to produce lower sulphur content oil products as well.

What Is More Important for Fourth-Grade Primary School Students for Transforming Their Potential into Achievement: The Individual or the Environmental Box in Multidimensional Conceptions of Giftedness?

ERIC Educational Resources Information Center

Stoeger, Heidrun; Steinbach, Julia; Obergriesser, Stefanie; Matthes, Benjamin

2014-01-01

Multidimensional models of giftedness specify individual and environmental moderators or catalysts that help transform potential into achievement. However, these models do not state whether the importance of the "individual boxes" and the "environmental boxes" changes during this process. The present study examines whether,…

Heterogeneous Organo-Catalysis: Sustainable Pathways to ...

EPA Pesticide Factsheets

Glucose and fructose are among the most abundant plant-derived materials1 and have been converted into useful building units often used in the drug discovery and polymer architecture.2 Unfortunately, most of these conversions require mineral acids and complex heterogeneous catalysis systems which suffer from the diminished activity and recyclability issues.3 Herein, we report a highly reactive and inexpensive heterogeneous sulfonated graphitic carbon nitride (Sg-CN), endowed with strong acidity that readily transforms carbohydrates to furanics. The ready availability and benign nature of the material and its stability over the several reaction cycles renders this catalyst very useful in organic synthesis, polymer industry and in the preparation of drug precursors. Poster presentation at the 253rd American Chemical Society (ACS) National meeting in San Francisco, CA

Anti-site defected MoS2 sheet for catalytic application

NASA Astrophysics Data System (ADS)

Sharma, Archana; Husain, Mushahid; Khan, Mohd. Shahid

2018-04-01

To prevent harmful and poisonous CO gas molecules, catalysts are needed for converting them into benign substances. Density functional theory (DFT) calculations have been used to investigate CO oxidation on the surface of MoS2 monolayer with Mo atom embedded at S-vacancy site (anti-site defect). The stronger interaction between Mo metal with O2 molecule as compared with CO molecule suggests high catalytic activity. The complete oxidation of CO is studied in a two-step procedure using Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms with a low overall energy barrier of 0.35 eV. Creation of anti-site defect makes the surface of MoS2 nanosheet catalytically active for the CO oxidation to take place.

Environmental quality alters female costs and benefits of evolving under enforced monogamy.

PubMed

Grazer, Vera M; Demont, Marco; Michalczyk, Łukasz; Gage, Matthew J G; Martin, Oliver Y

2014-02-05

Currently many habitats suffer from quality loss due to environmental change. As a consequence, evolutionary trajectories might shift due to environmental effects and potentially increase extinction risk of resident populations. Nevertheless, environmental variation has rarely been incorporated in studies of sexual selection and sexual conflict, although local environments and individuals' condition undoubtedly influence costs and benefits. Here, we utilise polyandrous and monogamous selection lines of flour beetles, which evolved in presence or absence of sexual selection for 39 generations. We specifically investigated effects of low vs. standard food quality (i.e. stressful vs. benign environments) on reproductive success of cross pairs between beetles from the contrasting female and male selection histories to assess gender effects driving fitness. We found a clear interaction of food quality, male selection history and female selection history. Monogamous females generally performed more poorly than polyandrous counterparts, but reproductive success was shaped by selection history of their mates and environmental quality. When monogamous females were paired with polyandrous males in the standard benign environment, females seemed to incur costs, possibly due to sexual conflict. In contrast, in the novel stressful environment, monogamous females profited from mating with polyandrous males, indicating benefits of sexual selection outweigh costs. Our findings suggest that costs and benefits of sexually selected adaptations in both sexes can be profoundly altered by environmental quality. With regard to understanding possible impacts of environmental change, our results further show that the ecology of mating systems and associated selection pressures should be considered in greater detail.

Visualising reacting single atoms under controlled conditions: Advances in atomic resolution in situ Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM)

NASA Astrophysics Data System (ADS)

Boyes, Edward D.; Gai, Pratibha L.

2014-02-01

Advances in atomic resolution Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM) for probing gas-solid catalyst reactions in situ at the atomic level under controlled reaction conditions of gas environment and temperature are described. The recent development of the ESTEM extends the capability of the ETEM by providing the direct visualisation of single atoms and the atomic structure of selected solid state heterogeneous catalysts in their working states in real-time. Atomic resolution E(S)TEM provides a deeper understanding of the dynamic atomic processes at the surface of solids and their mechanisms of operation. The benefits of atomic resolution-E(S)TEM to science and technology include new knowledge leading to improved technological processes with substantial economic benefits, improved healthcare, reductions in energy needs and the management of environmental waste generation. xml:lang="fr"

Selective isolation of gold facilitated by second-sphere coordination with α-cyclodextrin.

PubMed

Liu, Zhichang; Frasconi, Marco; Lei, Juying; Brown, Zachary J; Zhu, Zhixue; Cao, Dennis; Iehl, Julien; Liu, Guoliang; Fahrenbach, Albert C; Botros, Youssry Y; Farha, Omar K; Hupp, Joseph T; Mirkin, Chad A; Fraser Stoddart, J

2013-01-01

Gold recovery using environmentally benign chemistry is imperative from an environmental perspective. Here we report the spontaneous assembly of a one-dimensional supramolecular complex with an extended {[K(OH₂)₆][AuBr₄](α-cyclodextrin)₂}n chain superstructure formed during the rapid co-precipitation of α-cyclodextrin and KAuBr₄ in water. This phase change is selective for this gold salt, even in the presence of other square-planar palladium and platinum complexes. From single-crystal X-ray analyses of six inclusion complexes between α-, β- and γ-cyclodextrins with KAuBr₄ and KAuCl₄, we hypothesize that a perfect match in molecular recognition between α-cyclodextrin and [AuBr₄](-) leads to a near-axial orientation of the ion with respect to the α-cyclodextrin channel, which facilitates a highly specific second-sphere coordination involving [AuBr₄](-) and [K(OH₂)₆](+) and drives the co-precipitation of the 1:2 adduct. This discovery heralds a green host-guest procedure for gold recovery from gold-bearing raw materials making use of α-cyclodextrin-an inexpensive and environmentally benign carbohydrate.

Rhodamine B in dissolved and nano-bound forms: Indicators for light-based advanced oxidation processes.

PubMed

Shabat-Hadas, Efrat; Mamane, Hadas; Gitis, Vitaly

2017-10-01

Rhodamine B (RhB) is a water-soluble fluorescent dye that is often used to determine flux and flow direction in biotechnological and environmental applications. In the current research, RhB in soluble (termed free) and virus-bound (termed nano-bound) forms was used as an efficiency indicator for three environmental processes. The degradation of free and nano-bound RhB by (i) direct UV photolysis and (ii) UV/H 2 O 2 advanced oxidation process (AOP) was studied in a collimated beam apparatus equipped with medium-pressure mercury vapor lamp. The degradation by (iii) solar light-induced photocatalysis was studied in a solar simulator with titanium dioxide and bismuth photocatalysts. Results showed negligible RhB degradation by direct UV and solar light, and its nearly linear degradation by UV/H 2 O 2 and photocatalysis/photosensitization in the presence of a solid catalyst. Considerable adsorption of free RhB on bismuth-based catalyst vs. no adsorption of nano-bound RhB on this catalyst or of any form of the dye on titanium dioxide produced two important conclusions. First, the better degradation of free RhB by the bismuth catalyst suggests that close proximity of a catalyst hole and the decomposing molecule significantly influences degradation. Second, the soluble form of the dye might not be the best option for its use as an indicator. Nano-bound RhB showed high potential as an AOP indicator, featuring possible separation from water after the analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmentally Responsible Microbiological Production of Energetic Ingredients

DTIC Science & Technology

2007-11-01

effort was to develop an environmentally benign and economical microbial process for nitro-energetics production . The specific targets of this method...microbial production of nitro-based EM. As the processes and compounds of choice, RDX/HMX (nitramine) generation was selected. Microorganisms capable of...Current synthetic methods for the production of RDX and HMX utilize hexamine as the precursor. Hexamine is an industrial chemical available on a large

Environmentally Benign Stab Detonators

DTIC Science & Technology

2006-07-11

composition. In addition we will work with our DoD partner TACOM-ARDEC in identifying and testing more environmentally suitable replacement transfer...components identified is shown in Figure 1 below. Figure 1. Photo of M55 stab detonator Al cup with initiation train and components. Common...primer mixes, such as NOL-130, are made up of lead styphnate (basic) 40%, lead azide ( dextrinated ) 20%, barium nitrate 20%, antimony sulfide 15%, and

Demonstration of an Environmentally Benign and Reduced Corrosion Runway Deicing Fluid

DTIC Science & Technology

2011-01-01

ADDRESS(ES) Enviromental Security Technology Certification Program: 901 North Stuart Street, Suite 303, Arlington, Virginia 22203 10. SPONSOR...IMPLEMENTATION ISSUES Users may express concern because the Battelle-RDF is new and they may have reservations because of its potential damage to...several drivers for implementing a new , more environmentally friendly RDF. 1.3.1 Water Pollution Reduction The Clean Water Act (CWA) and its

Demonstration of an Environmentally Benign and Reduced Corrosion Runway Deicing Fluid

DTIC Science & Technology

2011-01-01

43201 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) Enviromental Security Technology...laboratory to the airfields and airports across the country. Users may express concern because the Battelle-RDFs are new and they may have...airfield anti-icing and deicing at WPAFB. 1.3 REGULATORY DRIVERS There are several drivers for implementing a new , more environmentally friendly

ENVIRONMENTALLY BENIGN MITIGATION OF MICROBIOLOGICALLY INFLUENCED CORROSION (MIC)

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

J. Robert Paterek; Gemma Husmillo; Amrutha Daram

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. The technical approach for this quarter includes the application of new methods of Capsicum sp. (pepper) extraction by soxhlet method and analysis of a new set of extracts by thin layer chromatography (TLC) and highmore » performance liquid chromatography (HPLC); isolation and cultivation of MIC-causing microorganisms from corroded pipeline samples; and evaluation of antimicrobial activities of the old set of pepper extracts in comparison with major components of known biocides and corrosion inhibitors. Twelve new extracts from three varieties of Capsicum sp. (Serrano, Habanero, and Chile de Arbol) were obtained by soxhlet extraction using 4 different solvents. Results of TLC done on these extracts showed the presence of capsaicin and some phenolic compounds, while that of HPLC detected capsaicin and dihydrocapsaicin peaks. More tests will be done to determine specific components. Additional isolates from the group of heterotrophic, acid-producing, denitrifying and sulfate-reducing bacteria were obtained from the pipeline samples submitted by gas companies. Isolates of interest will be used in subsequent antimicrobial testing and test-loop simulation system experiments. Results of antimicrobial screening of Capsicum sp. extracts and components of known commercial biocides showed comparable activities when tested against two strains of sulfate-reducing bacteria.« less

ENVIRONMENTALLY BENIGN MITIGATION OF MICROBIOLOGICALLY INFLUENCED CORROSION (MIC)

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

John J. Kilbane II; William Bogan

2004-01-31

The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. The technical approach for this quarter included the fractionation of extracts prepared from several varieties of pepper plants, and using several solvents, by high performance liquid chromatography (HPLC). A preliminary determination of antimicrobial activities ofmore » the new extracts and fractions using a growth inhibition assay, and evaluation of the extracts ability to inhibit biofilm formation was also performed. The analysis of multiple extracts of pepper plants and fractions of extracts of pepper plants obtained by HPLC illustrated that these extracts and fractions are extremely complex mixtures of chemicals. Gas chromatography-mass spectrometry was used to identify the chemical constituents of these extracts and fractions to the greatest degree possible. Analysis of the chemical composition of various extracts of pepper plants has illustrated the complexity of the chemical mixtures present, and while additional work will be performed to further characterize the extracts to identify bioactive compounds the focus of efforts should now shift to an evaluation of the ability of extracts to inhibit corrosion in mixed culture biofilms, and in pure cultures of bacterial types which are known or believed to be important in corrosion.« less

Resource Recovery and Reuse: Recycled Magnetically Separable Iron-based Catalysts for Phosphate Recovery and Arsenic Removal

EPA Science Inventory

Environmentally friendly processes that aid human and environmental health include recovering, recycling, and reusing limited natural resources and waste materials. In this study, we re-used Iron-rich solid waste materials from water treatment plants to synthesize magnetic iron-o...

Degradation of Environmental Contaminants with Water-Soluble Cobalt Catalysts: An Integrative Inorganic Chemistry Investigation

ERIC Educational Resources Information Center

Evans, Alexandra L.; Messersmith, Reid E.; Green, David B.; Fritsch, Joseph M.

2011-01-01

We present an integrative laboratory investigation incorporating skills from inorganic chemistry, analytical instrumentation, and physical chemistry applied to a laboratory-scale model of the environmental problem of chlorinated ethylenes in groundwater. Perchloroethylene (C[subscript 2]Cl[subscript 4], PCE) a common dry cleaning solvent,…

The Comparative Photodegradation Activities of Pentachlorophenol (PCP) and Polychlorinated Biphenyls (PCBs) Using UV Alone and TiO2-Derived Photocatalysts in Methanol Soil Washing Solution

PubMed Central

Zhou, Zeyu; Zhang, Yaxin; Wang, Hongtao; Chen, Tan; Lu, Wenjing

2014-01-01

Photochemical treatment is increasingly being applied to remedy environmental problems. TiO2-derived catalysts are efficiently and widely used in photodegradation applications. The efficiency of various photochemical treatments, namely, the use of UV irradiation without catalyst or with TiO2/graphene-TiO2 photodegradation methods was determined by comparing the photodegadation of two main types of hydrophobic chlorinated aromatic pollutants, namely, pentachlorophenol (PCP) and polychlorinated biphenyls (PCBs). Results show that photodegradation in methanol solution under pure UV irradiation was more efficient than that with either one of the catalysts tested, contrary to previous results in which photodegradation rates were enhanced using TiO2-derived catalysts. The effects of various factors, such as UV light illumination, addition of methanol to the solution, catalyst dosage, and the pH of the reaction mixture, were examined. The degradation pathway was deduced. The photochemical treatment in methanol soil washing solution did not benefit from the use of the catalysts tested. Pure UV irradiation was sufficient for the dechlorination and degradation of the PCP and PCBs. PMID:25254664

EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT

EPA Science Inventory

To meet the great need of replacing many harmful solvents commonly used by industry and the public with environmentally benign substitute solvents, the PARIS II solvent design software has been developed. Although the difficulty of successfully finding replacements increases with...

THE POTENTIAL ROLE OF REMOTE SENSING IN TRANSGENIC CROP MONITORING PROGRAMS

EPA Science Inventory

Sustainable agriculture combines efficient production with wise stewardship of the earth's resources. Development of environmentally benign production techniques is one focus of sustainable agriculture. The new transgenic crops producing toxic proteins that target specific crop p...

Super high-rate fabrication of high-purity carbon nanotube aerogels from floating catalyst method for oil spill cleaning

NASA Astrophysics Data System (ADS)

Khoshnevis, Hamed; Mint, Sandar Myo; Yedinak, Emily; Tran, Thang Q.; Zadhoush, Ali; Youssefi, Mostafa; Pasquali, Matteo; Duong, Hai M.

2018-02-01

In this study, we apply an advanced floating catalyst method to fabricate carbon nanotube (CNT) aerogels at super high deposition rate for oil spill cleaning. The aerogels consist of 3D porous network of stacking double-walled CNT bundles with low catalyst impurity (9%) and high thermal stability (650 °C). With high porosity, surface areas, and water contact angles, the CNT aerogels exhibit a high oil adsorption of up to 107 g/g and good reusability of up to four adsorption-burning cycles. This work suggests that the lightweight, porous, and super hydrophobic CNT aerogels can be promising sorbent materials for environmental applications.

Industrial Catalysis: A Practical Guide

NASA Astrophysics Data System (ADS)

Farrauto, Robert J.

Every student of chemistry, material science, and chemical engineering should be schooled in catalysis and catalytic reactions. The reason is quite simple; most products produced in the chemical and petroleum industry utilize catalysts to enhance the rate of reaction and selectivity to desired products. Catalysts are also extensively used to minimize harmful byproduct pollutants in environmental applications. Enhanced reaction rates translate to higher production volumes at lower temperatures with smaller and less exotic materials of construction necessary. When a highly selective catalyst is used, large volumes of desired products are produced with virtually no undesirable byproducts. Gasoline, diesel, home heating oil, and aviation fuels owe their performance quality to catalytic processing used to upgrade crude oil.

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.

Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

NASA Astrophysics Data System (ADS)

Dang, Trung-Dung; Banerjee, Arghya Narayan; Tran, Quang-Tung; Roy, Sudipta

2016-11-01

By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO2 and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO2 coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation.

Construction of High Activity Titanium Dioxide Crystal Surface Heterostructures and Characterization of Its Basic Properties

NASA Astrophysics Data System (ADS)

Wang, Chunxiao; Li, DanQi; Shen, Tingting; Lu, Cheng; Sun, Jing; Wang, Xikui

2018-01-01

Heterogeneous photocatalytic materials, which combine the advantages of photocatalytic materials and heterojunction, have been developed rapidly in the field of environmental pollution control. In this paper, TiO2 surface heterojunction catalysts with different catalytic activity were prepared by controlling the amount of HF, and their XRD characterization was also carried out. In addition, the optimum amount of HF was determined by photocatalytic degradation of simulated dye wastewater by methylene blue solution. And the optimal amount of catalyst and the optimal pH reaction conditions for degradation experiments were used to screen the highly reactive titania surface heterojunction system and its optimum application conditions. It provides the possibility of application in the degradation of industrial wastewater and environmental treatment.

Presidential Green Chemistry Challenge: 2009 Academic Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2009 award winner, Professor Krzysztof Matyjaszewski, developed Atom Transfer Radical Polymerization to make polymers with copper catalysts and environmentally friendly reducing agents.

New catalysts for coal liquefaction and new nanocrystalline catalysts synthesis methods

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

Linehan, J.C.; Matson, D.W.; Darab, J.G.

1994-09-01

The use of coal as a source of transportation fuel is currently economically unfavorable due to an abundant world petroleum supply and the relatively high cost of coal liquefaction. Consequently, a reduction in the cost of coal liquefaction, for example by using less and/or less costly catalysts or lower liquefaction temperatures, must be accomplished if coal is to play an significant role as a source of liquid feedstock for the petrochemical industry. The authors and others have investigated the applicability of using inexpensive iron-based catalysts in place of more costly and environmentally hazardous metal catalysts for direct coal liquefaction. Iron-basedmore » catalysts can be effective in liquefying coal and in promoting carbon-carbon bond cleavage in model compounds. The authors have been involved in an ongoing effort to develop and optimize iron-based powders for use in coal liquefaction and related petrochemical applications. Research efforts in this area have been directed at three general areas. The authors have explored ways to optimize the effectiveness of catalyst precursor species through use of nanocrystalline materials and/or finely divided powders. In this effort, the authors have developed two new nanophase material production techniques, Modified Reverse Micelle (MRM) and the Rapid Thermal Decomposition of precursors in Solution (RTDS). A second effort has been aimed at optimizing the effectiveness of catalysts by variations in other factors. To this, the authors have investigated the effect that the crystalline phase has on the capacity of iron-based oxide and oxyhydroxide powders to be effectively converted to an active catalyst phase under liquefaction conditions. And finally, the authors have developed methods to produce active catalyst precursor powders in quantities sufficient for pilot-scale testing. Major results in these three areas are summarized.« less

Nanostructured Co3O4 grown on nickel foam: An efficient and readily recyclable 3D catalyst for heterogeneous peroxymonosulfate activation.

PubMed

Yuan, Ruixia; Hu, Lin; Yu, Peng; Wang, Huaiyuan; Wang, Zhaohui; Fang, Jingyun

2018-05-01

Cobalt-based heterogeneous catalyst has been recognized as one of most efficient activators for peroxymonosulfate (PMS) decomposition, but usually suffers from the poor stability and difficulty to recover and reuse. Here easily recyclable cobalt oxide (Co 3 O 4 ) nanowires and nanoflowers grown on nickel foam (NF) are fabricated by a hydrothermal and calcination method. The prepared 3D Co 3 O 4 /NF catalyst is characterized and applied as a heterogeneous catalyst for PMS activation to generate sulfate radicals for decomposition of Acid Orange 7 (AO7). The results show that the AO7 degradation rate increases with cobalt loading and PMS dosage, but decreases with the increase of solution pH. The Co 3 O 4 /NF catalyst using 2 mM Co(NO 3 ) 2 ·6H 2 O as cobalt source exhibits highest activity, and almost complete decolorization could be achieved within 30 min. The diverse effects of coexisting anions (SO 4 2- , HCO 3 - , NO 3 - and Cl - ) on AO7 degradation are observed and explained. After 10 consecutive runs, excellent catalytic reactivity of the catalyst remains while the level of leached cobalt during the catalyst usage is much lower than the maximum allowable concentration in drinking and natural water. More importantly, the macroscopic Co 3 O 4 /NF catalyst shows advantage of easy recycling after application compared to traditional catalysts. It is believed that the as-prepared Co 3 O 4 /NF is promising to be an effective and green heterogeneous catalyst for PMS activation to degrade organic pollutants for environmental application. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst.

PubMed

Tripathi, Pranav K; Durbach, Shane; Coville, Neil J

2017-09-22

The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman I D / I G ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst.

Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst

PubMed Central

Durbach, Shane

2017-01-01

The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman ID/IG ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst. PMID:28937596

Active Hydrogenation Catalyst with a Structured, Peptide-Based Outer-Coordination Sphere

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

Jain, Avijita; Buchko, Garry W.; Reback, Matthew L.

2012-10-05

The synthesis, catalytic activity, and structural features of a rhodium-based hydrogenation catalyst containing a phosphine ligand coupled to a 14-residue peptide are reported. Both CD and NMR spectroscopy show that the peptide adopts a helical structure in 1:1:1 TFE/MeCN/H2O that is maintained when the peptide is attached to the ligand and when the ligand is attached to the metal complex. The metal complex hydrogenates aqueous solutions of 3-butenol to 1-butanol at 360 ± 50 turnovers/Rh/h at 294 K. This peptide- based catalyst represents a starting point for developing and characterizing a peptide-based outer-coordination sphere that can be used to introducemore » enzyme-like features into molecular catalysts. This work was funded by the US DOE Basic Energy Sciences, Chemical Sciences, Geoscience and Biosciences Division (AJ, JCL and WJS), the Office of Science Early Career Research Program through the Office of Basic Energy Sciences (GWB, MLR and WJS). Part of the research was conducted at the W.R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. Department of Energy’s Office of Biolog-ical and Environmental Research (BER) program located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. Department of Energy.« less

Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy and In Situ X-Ray Ptychography.

PubMed

Baier, Sina; Damsgaard, Christian D; Klumpp, Michael; Reinhardt, Juliane; Sheppard, Thomas; Balogh, Zoltan; Kasama, Takeshi; Benzi, Federico; Wagner, Jakob B; Schwieger, Wilhelm; Schroer, Christian G; Grunwaldt, Jan-Dierk

2017-06-01

When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell. Both reductive activation and reoxidation were applied. The core-shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM and in situ X-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C, in situ X-ray ptychography indicated the occurrence of structural changes also on the µm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core-shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlative in situ microscopy techniques for hierarchically designed catalysts.

Chemical and phase evolution of amorphous molybdenum sulfide catalysts for electrochemical hydrogen production [Chemical and phase evolution of amorphous molybdenum sulfide catalysts for electrochemical hydrogen production directly observed using environmental transmission electron microscopy

DOE PAGES

Lee, Sang Chul; Benck, Jesse D.; Tsai, Charlie; ...

2015-12-01

Amorphous MoS x is a highly active, earth-abundant catalyst for the electrochemical hydrogen evolution reaction. Previous studies have revealed that this material initially has a composition of MoS 3, but after electrochemical activation, the surface is reduced to form an active phase resembling MoS 2 in composition and chemical state. However, structural changes in the Mo Sx catalyst and the mechanism of the activation process remain poorly understood. In this study, we employ transmission electron microscopy (TEM) to image amorphous MoS x catalysts activated under two hydrogen-rich conditions: ex situ in an electrochemical cell and in situ in an environmentalmore » TEM. For the first time, we directly observe the formation of crystalline domains in the MoS x catalyst after both activation procedures as well as spatially localized changes in the chemical state detected via electron energy loss spectroscopy. Using density functional theory calculations, we investigate the mechanisms for this phase transformation and find that the presence of hydrogen is critical for enabling the restructuring process. Our results suggest that the surface of the amorphous MoS x catalyst is dynamic: while the initial catalyst activation forms the primary active surface of amorphous MoS 2, continued transformation to the crystalline phase during electrochemical operation could contribute to catalyst deactivation. Finally, these results have important implications for the application of this highly active electrocatalyst for sustainable H 2 generation.« less

Esterification free fatty acid in sludge palm oil using ZrO2/SO42- - rice husk ash catalyst

NASA Astrophysics Data System (ADS)

Hidayat, Arif; Sutrisno, Bachrun

2017-05-01

Indonesia, as one of the biggest palm oil producers and exporters in the world, is producing large amounts of low-grade oil such as sludge palm oil (SPO) from palm oil industries. The use of SPO can lower the cost of biodiesel production significantly, which makes SPO a highly potential alternative feedstock for biodiesel production. In this paper, the esterification of free fatty acid on sludge palm oil was studied using rice husk ash as heterogeneous solid catalysts. Heterogeneous solid catalysts offer significant advantages of eliminating separation, corrosion, toxicity and environmental problems. In this paper the esterification of SPO, a by-product from palm oil industry, in the presence of modified rice husk ash catalysts was studied. The rice husk ash catalysts were synthesized by impregnating of Zirconia (Zr) on rice husk ash followed by sulfonation. The rice husk ash catalysts were characterized by using different techniques, such as FT-IR, XRD, and porous analysis. The effects of the mass ratio of catalyst to oil (1 - 10%), the molar ratio of methanol to oil (4:1 - 10:1), and the reaction temperature (40 - 60°C) were studied for the conversion of free fatty acids (FFAs) to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to oil molar ratio of 10:1, the amount of catalyst of 10%w, and reaction temperature of 60°C.

PHOTOCROSSLINKED IMMOBILIZATION OF POLYELECTROLYTES FOR TEMPLATE ASSISTED ENZYMATIC POLYMERIZATION OF CONJUGATED POLYMERS

EPA Science Inventory

Growing demand in consumer electronics raises need for efficient, affordable, environmentally benign and biodegradable substitutes for current technologies. Printed circuit boards contain heavy metals such as antimony, silver, chromium, zinc, lead, tin and copper. According t...

Green Chemistry and Education.

ERIC Educational Resources Information Center

Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

2000-01-01

Many students today are profoundly interested in the sustainability of their world. Introduces Green Chemistry and its principles with teaching materials. Green Chemistry is the use of chemistry for pollution prevention and the design of chemical products and processes that are environmentally benign. (ASK)

Development and In Vitro Bioactivity Profiling of Alternative Sustainable Nanomaterials

EPA Science Inventory

Sustainable, environmentally benign nanomaterials (NMs) are being designed as alternatives based on functionality to conventional metal-based nanomaterials (NMs) in order to minimize potential risk to human health and the environment. Development of rapid methods to evaluate the ...

BIOREMEDIATION OF PETROLEUM HYDROCARBON CONTAMINANTS IN MARINE HABITATS

EPA Science Inventory

Bioremediation is being increasingly seen as an effective environmentally benign treatment for shorelines contaminated as a result of marine oil spills. Despite a relatively long history of research on oil-spill bioremediation, it remains an essentially empirical technology and m...

DIRECT SYNTHESIS OF TERTIARY AMINES IN WATER USING MICROWAVES

EPA Science Inventory

A direct synthesis of tertiary amines is presented that proceeds expeditiously via N-alkylation of amines using alkyl halides in alkaline aqueous medium. This environmentally benign reaction is accelerated upon exposure to microwave irradiation resulting in shortened reaction tim...

ENVIRONMENTALLY-BENIGN POLYTETRAFLUOROETHYLENE (PTFE) COATINGS FOR MOLD RELEASE - PHASE II

EPA Science Inventory

GVD proposes to develop high performance, volatile organic compound (VOC)-free and perfluorooctanoic acid (PFOA)-free, non-stick mold release coatings based on its novel polytetrafluoroethylene (PTFE) fluoropolymer technology. Most commercial mold release agents make use of...

Sustainable business makes dollars and sense.

PubMed Central

Fields, Scott

2002-01-01

The last decade has marked a radical change in the business of sustainability, say environmental activists and industrialists alike. On the wane are "greenwashing" campaigns in which corporations promote dubious environmental accomplishments to draw attention away from environmentally damaging practices. On the rise are corporate investments in sustainability programs, new types of environmental markets, and public demand for green products and investments. Once an afterthought, an annoyance, or a nonentity, sustainability is now often a focal point for businesses. No longer thought of as a business cost, environmentally benign practices are now viewed as a competitive advantage as companies seek to win both stockholders and customers. PMID:11882490

Sustainable business makes dollars and sense.

PubMed

Fields, Scott

2002-03-01

The last decade has marked a radical change in the business of sustainability, say environmental activists and industrialists alike. On the wane are "greenwashing" campaigns in which corporations promote dubious environmental accomplishments to draw attention away from environmentally damaging practices. On the rise are corporate investments in sustainability programs, new types of environmental markets, and public demand for green products and investments. Once an afterthought, an annoyance, or a nonentity, sustainability is now often a focal point for businesses. No longer thought of as a business cost, environmentally benign practices are now viewed as a competitive advantage as companies seek to win both stockholders and customers.

3D CNT macrostructure synthesis catalyzed by MgFe2O4 nanoparticles-A study of surface area and spinel inversion influence

NASA Astrophysics Data System (ADS)

Zampiva, Rúbia Young Sun; Kaufmann Junior, Claudir Gabriel; Pinto, Juliano Schorne; Panta, Priscila Chaves; Alves, Annelise Kopp; Bergmann, Carlos Pérez

2017-11-01

The MgFe2O4 spinel exhibits remarkable magnetic properties that open up numerous applications in biomedicine, the environment and catalysis. MgFe2O4 nanoparticles are excellent catalyst for carbon nanotube (CNT) production. In this work, we proposed to use MgFe2O4 nanopowder as a catalyst in the production of 3D macroscopic structures based on CNTs. The creation of these nanoengineered 3D architectures remains one of the most important challenges in nanotechnology. These systems have high potential as supercapacitors, catalytic electrodes, artificial muscles and in environmental applications. 3D macrostructures are formed due to an elevated density of CNTs. The quantity and quality of the CNTs are directly related to the catalyst properties. A heat treatment study was performed to produce the most effective catalyst. Factors such as superficial area, spinel inversion, crystallite size, degree of agglomeration and its correlation with van der Waals forces were examined. As result, the ideal catalyst properties for CNT production were determined and high-density 3D CNT macrostructures were produced successfully.

High performance of a cobalt–nitrogen complex for the reduction and reductive coupling of nitro compounds into amines and their derivatives

PubMed Central

Zhou, Peng; Jiang, Liang; Wang, Fan; Deng, Kejian; Lv, Kangle; Zhang, Zehui

2017-01-01

Replacement of precious noble metal catalysts with low-cost, non-noble heterogeneous catalysts for chemoselective reduction and reductive coupling of nitro compounds holds tremendous promise for the clean synthesis of nitrogen-containing chemicals. We report a robust cobalt–nitrogen/carbon (Co–Nx/C-800-AT) catalyst for the reduction and reductive coupling of nitro compounds into amines and their derivates. The Co–Nx/C-800-AT catalyst was prepared by the pyrolysis of cobalt phthalocyanine–silica colloid composites and the subsequent removal of silica template and cobalt nanoparticles. The Co–Nx/C-800-AT catalyst showed extremely high activity, chemoselectivity, and stability toward the reduction of nitro compounds with H2, affording full conversion and >97% selectivity in water after 1.5 hours at 110°C and under a H2 pressure of 3.5 bar for all cases. The hydrogenation of nitrobenzene over the Co–Nx/C-800-AT catalyst can even be smoothly performed under very mild conditions (40°C and a H2 pressure of 1 bar) with an aniline yield of 98.7%. Moreover, the Co–Nx/C-800-AT catalyst has high activity toward the transfer hydrogenation of nitrobenzene into aniline and the reductive coupling of nitrobenzene into other derivates with high yields. These processes were carried out in an environmentally friendly manner without base and ligands. PMID:28232954

Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap

PubMed Central

Karunagaran, Ramesh; Coghlan, Campbell; Gulati, Karan; Tung, Tran Thanh; Doonan, Christian

2018-01-01

Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism. PMID:29382103

Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap.

PubMed

Karunagaran, Ramesh; Coghlan, Campbell; Shearer, Cameron; Tran, Diana; Gulati, Karan; Tung, Tran Thanh; Doonan, Christian; Losic, Dusan

2018-01-28

Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism.

Potential Toxicity and Underlying Mechanisms Associated with Pulmonary Exposure to Iron Oxide Nanoparticles: Conflicting Literature and Unclear Risk

PubMed Central

Kornberg, Tiffany G.; Antonini, James M.; Rojanasakul, Yon; Castranova, Vincent; Rojanasakul, Liying W.

2017-01-01

Fine/micron-sized iron oxide particulates are incidentally released from a number of industrial processes, including iron ore mining, steel processing, welding, and pyrite production. Some research suggests that occupational exposure to these particulates is linked to an increased risk of adverse respiratory outcomes, whereas other studies suggest that iron oxide is biologically benign. Iron oxide nanoparticles (IONPs), which are less than 100 nm in diameter, have recently surged in use as components of novel drug delivery systems, unique imaging protocols, as environmental catalysts, and for incorporation into thermoplastics. However, the adverse outcomes associated with occupational exposure to IONPs remain relatively unknown. Relevant in vivo studies suggest that pulmonary exposure to IONPs may induce inflammation, pulmonary fibrosis, genotoxicity, and extra-pulmonary effects. This correlates well with in vitro studies that utilize relevant dose, cell type(s), and meaningful end points. A majority of these adverse outcomes are attributed to increased oxidative stress, most likely caused by particle internalization, dissolution, release of free iron ions, and disruption of iron homeostasis. However, because the overall toxicity profile of IONPs is not well understood, it is difficult to set safe exposure limit recommendations that would be adequate for the protection of at-risk workers. This review article will focus on known risks following IONPs exposure supported by human, animal, and cell culture-based studies, the potential challenges intrinsic to IONPs toxicity assessment, and how these may contribute to the poorly characterized IONPs toxicity profile. PMID:28984829

Preparation and controlled drug delivery applications of mesoporous silica polymer nanocomposites through the visible light induced surface-initiated ATRP

NASA Astrophysics Data System (ADS)

Huang, Long; Liu, Meiying; Mao, Liucheng; Xu, Dazhuang; Wan, Qing; Zeng, Guangjian; Shi, Yingge; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2017-08-01

The mesoporous materials with large pore size, high specific surface area and high thermal stability have been widely utilized in a variety of fields ranging from environmental remediation to separation and biomedicine. However, surface modification of these silica nanomaterials is required to endow novel properties and achieve better performance for most of these applications. In this work, a new method has been established for surface modification of mesoporous silica nanoparticles (MSNs) that relied on the visible light induced atom transfer radical polymerization (ATRP). In the procedure, the copolymers composited with itaconic acid (IA) and poly(ethylene glycol)methyl acrylate (PEGMA) were grafted from MSNs using IA and PEGMA as the monomers and 10-Phenylphenothiazine(PTH) as the organic catalyst. The successful preparation of final polymer nanocomposites (named as MSNs-NH2-poly(IA-co-PEGMA)) were evidenced by a series of characterization techniques. More importantly, the anticancer agent cisplatin can be effectively loaded on MSNs-NH2-poly(IA-co-PEGMA) and controlled release it from the drug-loading composites with pH responsive behavior. As compared with conventional ATRP, the light induced surface-initiated ATRP could also be utilized for preparation of various silica polymer nanocomposites under rather benign conditions (e.g. absent of transition metal ions, low polymerization temperature and short polymerization time). Taken together, we have developed a rather promising strategy method for fabrication of multifunctional MSNs-NH2-poly(IA-co-PEGMA) with great potential for biomedical applications.

Electronic Modulation of Electrocatalytically Active Center of Cu7S4 Nanodisks by Cobalt-Doping for Highly Efficient Oxygen Evolution Reaction.

PubMed

Li, Qun; Wang, Xianfu; Tang, Kai; Wang, Mengfan; Wang, Chao; Yan, Chenglin

2017-12-26

Cu-based electrocatalysts have seldom been studied for water oxidation because of their inferior activity and poor stability regardless of their low cost and environmentally benign nature. Therefore, exploring an efficient way to improve the activity of Cu-based electrocatalysts is very important for their practical application. Modifying electronic structure of the electrocatalytically active center of electrocatalysts by metal doping to favor the electron transfer between catalyst active sites and electrode is an important approach to optimize hydrogen and oxygen species adsorption energy, thus leading to the enhanced intrinsic electrocatalytic activity. Herein, Co-doped Cu 7 S 4 nanodisks were synthesized and investigated as highly efficient electrocatalyst for oxygen evolution reaction (OER) due to the optimized electronic structure of the active center. Density-functional theory (DFT) calculations reveal that Co-engineered Cu 7 S 4 could accelerate electron transfer between Co and Cu sites, thus decrease the energy barriers of intermediates and products during OER, which are crucial for enhanced catalytic properties. As expected, Co-engineered Cu 7 S 4 nanodisks exhibit a low overpotential of 270 mV to achieve current density of 10 mA cm -2 as well as decreased Tafel slope and enhanced turnover frequencies as compared to bare Cu 7 S 4 . This discovery not only provides low-cost and efficient Cu-based electrocatalyst by Co doping, but also exhibits an in-depth insight into the mechanism of the enhanced OER properties.

Catalyst Substrates Remove Contaminants, Produce Fuel

NASA Technical Reports Server (NTRS)

2012-01-01

A spacecraft is the ultimate tight building. We don t want any leaks, and there is very little fresh air coming in, says Jay Perry, an aerospace engineer at Marshall Space Flight Center. As a result, there is a huge potential for a buildup of contaminants from a host of sources. Inside a spacecraft, contaminants can be introduced from the materials that make spacecraft components, electronics boxes, or activities by the crew such as food preparation or cleaning. Humans also generate contaminants by breathing and through the body s natural metabolic processes. As part of the sophisticated Environmental Control and Life Support System on the International Space Station (ISS), a trace contaminant control system removes carbon dioxide and other impurities from the cabin atmosphere. To maintain healthy levels, the system uses adsorbent media to filter chemical contaminant molecules and a high-temperature catalytic oxidizer to change the chemical structure of the contaminants to something more benign, usually carbon dioxide and water. In the 1990s, while researching air quality control technology for extended spaceflight travel, Perry and others at Marshall were looking for a regenerable process for the continuous removal of carbon dioxide and trace chemical contaminants on long-duration manned space flights. At the time, the existing technology used on U.S. spacecraft could only be used once, which meant that a spacecraft had to carry additional spare parts for use in case the first one was depleted, or the spacecraft would have to return to Earth to exchange the components.

Measurement of the Dewetting, Nucleation, and Deactivation Kinetics of Carbon Nanotube Population Growth by Environmental Transmission Electron Microscopy

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

Bedewy, Mostafa; Viswanath, B.; Meshot, Eric R.

In order to understand the collective growth of carbon nanotube (CNT) populations tailoring their properties for many applications is key. During the initial stages of CNT growth by chemical vapor deposition, catalyst nanoparticle formation by thin-film dewetting and the subsequent CNT nucleation processes dictate the CNT diameter distribution, areal density, and alignment. We use in situ environmental transmission electron microscopy (E-TEM) to observe the catalyst annealing, growth, and deactivation stages for a population of CNTs grown from a thin-film catalyst. Complementary in situ electron diffraction and TEM imaging show that, during the annealing step in hydrogen, reduction of the ironmore » oxide catalyst is concomitant with changes in the thin-film morphology; complete dewetting and the formation of a population of nanoparticles is only achieved upon the introduction of the carbon source, acetylene. The dewetting kinetics, i.e., the appearance of distinct nanoparticles, exhibits a sigmoidal (autocatalytic) curve with 95% of all nanoparticles appearing within 6 s. After nanoparticles form, they either nucleate CNTs or remain inactive, with incubation times measured to be as small as 3.5 s. Via E-TEM we also directly observe the crowding and self-alignment of CNTs after dewetting and nucleation. Additionally, in situ electron energy loss spectroscopy reveals that the collective rate of carbon accumulation decays exponentially. We conclude that the kinetics of catalyst formation and CNT nucleation must both be addressed in order to achieve uniform and high CNT density, and their transient behavior may be a primary cause of the well-known nonuniform density of CNT forests.« less

Measurement of the Dewetting, Nucleation, and Deactivation Kinetics of Carbon Nanotube Population Growth by Environmental Transmission Electron Microscopy

DOE PAGES

Bedewy, Mostafa; Viswanath, B.; Meshot, Eric R.; ...

2016-05-23

In order to understand the collective growth of carbon nanotube (CNT) populations tailoring their properties for many applications is key. During the initial stages of CNT growth by chemical vapor deposition, catalyst nanoparticle formation by thin-film dewetting and the subsequent CNT nucleation processes dictate the CNT diameter distribution, areal density, and alignment. We use in situ environmental transmission electron microscopy (E-TEM) to observe the catalyst annealing, growth, and deactivation stages for a population of CNTs grown from a thin-film catalyst. Complementary in situ electron diffraction and TEM imaging show that, during the annealing step in hydrogen, reduction of the ironmore » oxide catalyst is concomitant with changes in the thin-film morphology; complete dewetting and the formation of a population of nanoparticles is only achieved upon the introduction of the carbon source, acetylene. The dewetting kinetics, i.e., the appearance of distinct nanoparticles, exhibits a sigmoidal (autocatalytic) curve with 95% of all nanoparticles appearing within 6 s. After nanoparticles form, they either nucleate CNTs or remain inactive, with incubation times measured to be as small as 3.5 s. Via E-TEM we also directly observe the crowding and self-alignment of CNTs after dewetting and nucleation. Additionally, in situ electron energy loss spectroscopy reveals that the collective rate of carbon accumulation decays exponentially. We conclude that the kinetics of catalyst formation and CNT nucleation must both be addressed in order to achieve uniform and high CNT density, and their transient behavior may be a primary cause of the well-known nonuniform density of CNT forests.« less

High-Valent Organometallic Copper and Palladium in Catalysis

PubMed Central

Hickman, Amanda J.; Sanford, Melanie S.

2015-01-01

Preface Copper and palladium catalysts are critically important for numerous commercial chemical processes. Improvements in the activity, selectivity, and scope of these catalysts have the potential to dramatically reduce the environmental impact and increase the sustainability of chemical reactions. One rapidly emerging strategy to achieve these goals is to exploit “high-valent” copper and palladium intermediates in catalysis. This review describes exciting recent advances involving both the fundamental chemistry and the applications of these high-valent metal complexes in numerous synthetically useful catalytic transformations. PMID:22498623

Industrial applications of enzyme biocatalysis: Current status and future aspects.

PubMed

Choi, Jung-Min; Han, Sang-Soo; Kim, Hak-Sung

2015-11-15

Enzymes are the most proficient catalysts, offering much more competitive processes compared to chemical catalysts. The number of industrial applications for enzymes has exploded in recent years, mainly owing to advances in protein engineering technology and environmental and economic necessities. Herein, we review recent progress in enzyme biocatalysis, and discuss the trends and strategies that are leading to broader industrial enzyme applications. The challenges and opportunities in developing biocatalytic processes are also discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

Environmentally Benign Battlefield Effects Black Smoke Simulator

DTIC Science & Technology

2006-11-01

tested and results Fuel Oxidizer Color of Smoke Density of Smoke Sugar (Sucrose) KNO3 Grey Medium Dextrin KNO3 Grey Thin Microcrystalline...design. 3.5 Initial Prototype Scale Fiberboard Testing Several quality black smoke formulations were identified in the small pellet testing to

Leaving A Mark: A Comparison Arthropod Protein Marking Protocols

USDA-ARS?s Scientific Manuscript database

Knowledge of arthropod pest and natural enemy disperal patterns is needed for effective and environmentally benign pest control. The most common tactics used to monitor arthropod dispersal patterns include mark-release-recapture (MRR) and mark-capture methodologies. Both methods require the applica...

Innovative green technique for preparing of flame retardant cotton

USDA-ARS?s Scientific Manuscript database

Due to its environmentally benign character, microwave-assisted or supercritical carbon dioxide high pressure reactors are considered in green chemistry as a substitute for organic solvents in chemical reactions. In this paper, an innovative approach for preparation of flame retardant cotton fabric ...

ENVIRONMENTALLY BENIGN PROCESS RESEARCH: LINKING USEPA CHEMICAL PROCESS DESIGN AND SUSTAINABILITY

EPA Science Inventory

Interest in sustainability has increased dramatically over the last decade. Declarations have been made on what sustainable development is: meeting today's needs without compromising future needs (Brundtland, 1987). Others have focused on what sustainability means in terms of s...

DYNAMIC MODELING AND SIMULATION FOR ENVIRONMENTALLY BENIGN CLEANING AND RINSING. (R824732)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Greener and Sustainable Approaches to the Synthesis of Pharmaceutically Active Heterocycles

EPA Science Inventory

Green chemistry is a rapidly developing field providing a proactive avenue for the sustainable development of future science and technology. Green chemistry can be applied to the design of highly efficient, environmentally benign synthetic protocols to deliver life-saving medicin...

Silicene catalyzed reduction of nitrobenzene to aniline: A mechanistic study

NASA Astrophysics Data System (ADS)

Morrissey, Christopher; He, Haiying

2018-03-01

The reduction of nitrobenzene to aniline has broad applications in chemical and pharmaceutical industries. The high reaction temperatures and pressures and unavoidable hazardous chemicals of current metal catalysts call for more environmentally friendly non-metal catalysts. In this study, the plausibility of silicene as a potential catalyst for nitrobenzene reduction is investigated with a focus on the distinct reaction mechanism based on the density functional theory. The direct reaction pathway was shown to be distinctly different from the Haber mechanism following PhNO2∗ → PhNO∗ → PhNHO∗ → PhNH2O∗ → PhNH2∗. The hydroxyl groups remain bound to silicene after aniline is formed and acquire a high activation barrier to remove.

GREEN CHEMISTRY. Shape-selective zeolite catalysis for bioplastics production.

PubMed

Dusselier, Michiel; Van Wouwe, Pieter; Dewaele, Annelies; Jacobs, Pierre A; Sels, Bert F

2015-07-03

Biodegradable and renewable polymers, such as polylactic acid, are benign alternatives for petrochemical-based plastics. Current production of polylactic acid via its key building block lactide, the cyclic dimer of lactic acid, is inefficient in terms of energy, time, and feedstock use. We present a direct zeolite-based catalytic process, which converts lactic acid into lactide. The shape-selective properties of zeolites are essential to attain record lactide yields, outperforming those of the current multistep process by avoiding both racemization and side-product formation. The highly productive process is strengthened by facile recovery and practical reactivation of the catalyst, which remains structurally fit during at least six consecutive reactions, and by the ease of solvent and side-product recycling. Copyright © 2015, American Association for the Advancement of Science.

Environmentally friendly chemoselective oxidation of primary aliphatic amines by using a biomimetic electrocatalytic system.

PubMed

Largeron, Martine; Chiaroni, Angèle; Fleury, Maurice-Bernard

2008-01-01

Environmentally friendly oxidation of primary aliphatic amines to imines has been successfully achieved, under metal-free conditions, by the use of diverse electrogenerated o-azaquinone mediators. High catalytic performance, together with high chemoselectivity, were observed with electron-poor o-azaquinone catalysts generated from 2-aminoresorcinol derivatives. Similar to copper amine oxidase enzymes, these mediators exhibited lower reactivity toward alpha-branched primary amines and no reactivity toward secondary amines. In the case of 3,4-aminophenol derivatives lacking a 2-hydroxy group, the generated o-azaquinone species failed to catalyze the oxidation of the amine to the corresponding imine. Further mechanistic considerations allowed a rationalization of the crucial role of the 2-hydroxy group in converting a catalytically inert species into a highly effective biomimetic catalyst.

Novel utilization of waste marine sponge (Demospongiae) as a catalyst in ultrasound-assisted transesterification of waste cooking oil.

PubMed

Hindryawati, Noor; Maniam, Gaanty Pragas

2015-01-01

This study demonstrates the potential of Na-silica waste sponge as a source of low cost catalyst in the transesterification of waste cooking oil aided by ultrasound. In this work an environmentally friendly and efficient transesterification process using Na-loaded SiO2 from waste sponge skeletons as a solid catalyst is presented. The results showed that the methyl esters content of 98.4±0.4wt.% was obtainable in less than an hour (h) of reaction time at 55°C. Optimization of reaction parameters revealed that MeOH:oil, 9:1; catalyst, 3wt.% and reaction duration of 30min as optimum reaction conditions. The catalyst is able to tolerant free fatty acid and moisture content up to 6% and 8%, respectively. In addition, the catalyst can be reused for seven cycles while maintaining the methyl esters content at 86.3%. Ultrasound undoubtedly assisted in achieving this remarkable result in less than 1h reaction time. For the kinetics study at 50-60°C, a pseudo first order model was proposed, and the activation energy of the reaction is determined as 33.45kJ/mol using Arrhenius equation. Copyright © 2014 Elsevier B.V. All rights reserved.

A review of metal recovery from spent petroleum catalysts and ash.

PubMed

Akcil, Ata; Vegliò, Francesco; Ferella, Francesco; Okudan, Mediha Demet; Tuncuk, Aysenur

2015-11-01

With the increase in environmental awareness, the disposal of any form of hazardous waste has become a great concern for the industrial sector. Spent catalysts contribute to a significant amount of the solid waste generated by the petrochemical and petroleum refining industry. Hydro-cracking and hydrodesulfurization (HDS) catalysts are extensively used in the petroleum refining and petrochemical industries. The catalysts used in the refining processes lose their effectiveness over time. When the activity of catalysts decline below the acceptable level, they are usually regenerated and reused but regeneration is not possible every time. Recycling of some industrial waste containing base metals (such as V, Ni, Co, Mo) is estimated as an economical opportunity in the exploitation of these wastes. Alkali roasted catalysts can be leached in water to get the Mo and V in solution (in which temperature plays an important role during leaching). Several techniques are possible to separate the different metals, among those selective precipitation and solvent extraction are the most used. Pyrometallurgical treatment and bio-hydrometallurgical leaching were also proposed in the scientific literature but up to now they did not have any industrial application. An overview on patented and commercial processes was also presented. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biodiesel production from non-edible Silybum marianum oil using heterogeneous solid base catalyst under ultrasonication.

PubMed

Takase, Mohammed; Chen, Yao; Liu, Hongyang; Zhao, Ting; Yang, Liuqing; Wu, Xiangyang

2014-09-01

The aim of this study is to investigate modified TiO2 doped with C4H4O6HK as heterogeneous solid base catalyst for transesterification of non-edible, Silybum marianum oil to biodiesel using methanol under ultrasonication. Upon screening the catalytic performance of modified TiO2 doped with different K-compounds, 0.7 C4H4O6HK doped on TiO2 was selected. The preparation of the catalyst was done using incipient wetness impregnation method. Having doped modified TiO2 with C4H4O6HK, followed by impregnation, drying and calcination at 600 °C for 6 h, the catalyst was characterized by XRD, FTIR, SEM, BET, TGA, UV and the Hammett indicators. The yield of the biodiesel was proportional to the catalyst basicity. The catalyst had granular and porous structures with high basicity and superior performance. Combined conditions of 16:1 molar ratio of methanol to oil, 5 wt.% catalyst amount, 60 °C reaction temperature and 30 min reaction time was enough for maximum yield of 90.1%. The catalyst maintained sustained activity after five cycles of use. The oxidative stability which was the main problem of the biodiesel was improved from 2.0 h to 3.2h after 30 days using ascorbic acid as antioxidant. The other properties including the flash point, cetane number and the cold flow ones were however, comparable to international standards. The study indicated that Ti-0.7-600-6 is an efficient, economical and environmentally, friendly catalyst under ultrasonication for producing biodiesel from S. marianum oil with a substantial yield. Copyright © 2014 Elsevier B.V. All rights reserved.

Selective isolation of gold facilitated by second-sphere coordination with α-cyclodextrin

PubMed Central

Liu, Zhichang; Frasconi, Marco; Lei, Juying; Brown, Zachary J.; Zhu, Zhixue; Cao, Dennis; Iehl, Julien; Liu, Guoliang; Fahrenbach, Albert C.; Botros, Youssry Y.; Farha, Omar K.; Hupp, Joseph T.; Mirkin, Chad A.; Fraser Stoddart, J.

2013-01-01

Gold recovery using environmentally benign chemistry is imperative from an environmental perspective. Here we report the spontaneous assembly of a one-dimensional supramolecular complex with an extended {[K(OH2)6][AuBr4](α-cyclodextrin)2}n chain superstructure formed during the rapid co-precipitation of α-cyclodextrin and KAuBr4 in water. This phase change is selective for this gold salt, even in the presence of other square-planar palladium and platinum complexes. From single-crystal X-ray analyses of six inclusion complexes between α-, β- and γ-cyclodextrins with KAuBr4 and KAuCl4, we hypothesize that a perfect match in molecular recognition between α-cyclodextrin and [AuBr4]− leads to a near-axial orientation of the ion with respect to the α-cyclodextrin channel, which facilitates a highly specific second-sphere coordination involving [AuBr4]− and [K(OH2)6]+ and drives the co-precipitation of the 1:2 adduct. This discovery heralds a green host–guest procedure for gold recovery from gold-bearing raw materials making use of α-cyclodextrin—an inexpensive and environmentally benign carbohydrate. PMID:23673640

Esterification of oleic acid with alcohols over Cu-MMT K10 and Fe-MMT K10 as acid catalysts

NASA Astrophysics Data System (ADS)

Harun, Farah Wahida; Jihadi, Nurul â.€˜Izzati Mohd; Ramli, Shaima'; Hassan, Nurul Rabiatul Adawiyah; Zubir, â.€˜Nur'Atikah Mat

2018-06-01

The esterification of free fatty acids with alcohols using montmorillonite (MMT) clay as heterogeneous catalyst is one of the methods to produce fatty acid alkyl ester that can be used as alternative renewable biofuels. However, the unmodified MMT gives low conversion of free fatty due to the limitation of acid sites in the clay structure. This work focuses on preparation of an environmental friendly catalyst from montmorillonite K10 (MMT K10) clay catalyst for the esterification of oleic acid with various alcohols. Esterification of oleic acid with alcohols has been carried out in the presence of metal exchanged MMT K10 (M-MMT K10; M = Fe3+ and Cu2+). The concentrations of both Fe3+ and Cu2+ precursors were varied at 1 M and 4 M. The effect of different alcohols used, molar ratio of reactants and catalyst loading on the esterification reaction was investigated. Among the exchanged clay catalysts, 4 M Fe-MMT K10 was found to be more active for the esterification of oleic acid with methanol. The maximum oleic acid conversion (ca. 68.5%) was achieved after 3 hours of reaction at the reaction temperature of 60 oC with molar ratio of methanol to oleic acid of 10:1 and catalyst loading of 5 wt% relative to the mass of oleic acid. The catalytic activity was found to be directly related to the amount of cation used in the modification step and Brønsted acidity of metal exchanged MMT K10 clay catalyst.

Environmental Technology Verification: Test Report of Mobile Source Selective Catalytic Reduction--Nett Technologies, Inc., BlueMAX 100 version A urea-based selective catalytic reduction technology

EPA Science Inventory

Nett Technologies’ BlueMAX 100 version A Urea-Based SCR System utilizes a zeolite catalyst coating on a cordierite honeycomb substrate for heavy-duty diesel nonroad engines for use with commercial ultra-low–sulfur diesel fuel. This environmental technology verification (ETV) repo...

ENVIRONMENTAL TECHNOLOGY VERIFICATION--TEST REPORT OF MOBILE SOURCE EMISSION CONTROL DEVICES, CUMMINS EMISSION SOLUTIONS AND CUMMINS FILTRATION DIESEL OXIDATION CATALYST AND CLOSED CRANKCASE VENTILATION SYSTEM

EPA Science Inventory

The U.S. EPA has created the Environmental Technology Verification (ETV) Program. ETV seeks to provide high-quality, peer-reviewed data on technology performance. The Air Pollution Control Technology (APCT) Verification Center, a center under the ETV Program, is operated by Res...

MICROWAVE-ASSISTED SYNTHESIS OF NITROGEN AND OXYGEN CONTAINING HETEROCYCLES IN AQUEOUS MEDIUM

EPA Science Inventory

Pharmaceutical scientists are required to generate diverse arrays of complex targets in short periods of time. A primary driver of organic chemistry is, therefore, the development of efficient and environmentally benign synthetic protocols. This can be achieved via the selection ...

Bare Magnetic Nanoparticles: Sustainable Synthesis and Applications in Catalytic Organic Transformations

EPA Science Inventory

Magnetic nanoparticles have become increasingly prominent in the field of catalysis over the last decade as they combine interesting reactivity with an easy, economical and environmentally benign mode of recovery. Early strategies focused on the use of such nanoparticles only as ...

Greener Biomimetic Synthesis of Nanomaterials using Anti-oxidants from Plants and Microwaves

EPA Science Inventory

The generation of nanoparticles often requires aggressive reducing agents and the cost of production is relatively high both materially and environmentally. Greener synthetic strategies are advanced via several pathways using benign reagents in the matrix in which they are to be ...

Extraction of Pentachlorophenol from Soils using Environmentally Benign Lactic Acid Solutions

EPA Science Inventory

Soil contamination with pentachlorophenol (PCP) is widespread across the globe. Soil washing/extraction is a common technique to remove this compound. Several soil washing/extraction solutions have been used but a majority of them have the problem of persistence in the environmen...

Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

PubMed Central

Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

2015-01-01

Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices. PMID:25650133

Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage.

PubMed

Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

2015-02-04

Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices.

Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

2013-01-01

Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts. Preferably, the hydrogenation catalyst is a bimetallic particle formed from a zero-valent iron or zero-valent magnesium particle coated with palladium that is impregnated onto a high-surface-area graphite support. The zero-valent metal particles should be microscale or nanoscale zero-valent magnesium or zero-valent iron particles. Other zero-valent metal particles and combinations may be used. Additionally, the base material may be selected from a variety of minerals including, but not limited to, alumina and zeolites. The catalytic metal is preferably selected from the group consisting of noble metals and transition metals, preferably palladium. The mechanical milling process includes milling the base material with a catalytic metal impregnated into a high-surface-area support to form the hydrogenation catalyst. In a preferred mechanical milling process, a zero-valent metal particle is provided as the base material, preferably having a particle size of less than about 10 microns, preferably 0.1 to 10 microns or smaller, prior to milling. The catalytic metal is supported on a conductive carbon support structure prior to milling. For example, palladium may be impregnated on a graphite support. Other support structures such as semiconductive metal oxides may also be used.

A complex social-ecological disaster: Environmentally induced forced migration

PubMed Central

Rechkemmer, Andreas; O'Connor, Ashley; Rai, Abha; Decker Sparks, Jessica L.; Mudliar, Pranietha; Shultz, James M.

2016-01-01

ABSTRACT In the 21st century, global issues are increasingly characterized by inter-connectedness and complexity. Global environmental change, and climate change in particular, has become a powerful driver and catalyst of forced migration and internal displacement of people. Environmental migrants may far outnumber any other group of displaced people and refugees in the years to come. Deeper scientific integration, especially across the social sciences, is a prerequisite to tackle this issue.

A complex social-ecological disaster: Environmentally induced forced migration.

PubMed

Rechkemmer, Andreas; O'Connor, Ashley; Rai, Abha; Decker Sparks, Jessica L; Mudliar, Pranietha; Shultz, James M

2016-01-01

In the 21 st century, global issues are increasingly characterized by inter-connectedness and complexity. Global environmental change, and climate change in particular, has become a powerful driver and catalyst of forced migration and internal displacement of people. Environmental migrants may far outnumber any other group of displaced people and refugees in the years to come. Deeper scientific integration, especially across the social sciences, is a prerequisite to tackle this issue.

A new high temperature reactor for operando XAS: Application for the dry reforming of methane over Ni/ZrO2 catalyst.

PubMed

Aguilar-Tapia, Antonio; Ould-Chikh, Samy; Lahera, Eric; Prat, Alain; Delnet, William; Proux, Olivier; Kieffer, Isabelle; Basset, Jean-Marie; Takanabe, Kazuhiro; Hazemann, Jean-Louis

2018-03-01

The construction of a high-temperature reaction cell for operando X-ray absorption spectroscopy characterization is reported. A dedicated cell was designed to operate as a plug-flow reactor using powder samples requiring gas flow and thermal treatment at high temperatures. The cell was successfully used in the reaction of dry reforming of methane (DRM). We present X-ray absorption results in the fluorescence detection mode on a 0.4 wt. % Ni/ZrO 2 catalyst under realistic conditions at 750 °C, reproducing the conditions used for a conventional dynamic microreactor for the DRM reaction. The setup includes a gas distribution system that can be fully remotely operated. The reaction cell offers the possibility of transmission and fluorescence detection modes. The complete setup dedicated to the study of catalysts is permanently installed on the Collaborating Research Groups French Absorption spectroscopy beamline in Material and Environmental sciences (CRG-FAME) and French Absorption spectroscopy beamline in Material and Environmental sciences at Ultra-High Dilution (FAME-UHD) beamlines (BM30B and BM16) at the European Synchrotron Radiation Facility in Grenoble, France.

A new high temperature reactor for operando XAS: Application for the dry reforming of methane over Ni/ZrO2 catalyst

NASA Astrophysics Data System (ADS)

Aguilar-Tapia, Antonio; Ould-Chikh, Samy; Lahera, Eric; Prat, Alain; Delnet, William; Proux, Olivier; Kieffer, Isabelle; Basset, Jean-Marie; Takanabe, Kazuhiro; Hazemann, Jean-Louis

2018-03-01

The construction of a high-temperature reaction cell for operando X-ray absorption spectroscopy characterization is reported. A dedicated cell was designed to operate as a plug-flow reactor using powder samples requiring gas flow and thermal treatment at high temperatures. The cell was successfully used in the reaction of dry reforming of methane (DRM). We present X-ray absorption results in the fluorescence detection mode on a 0.4 wt. % Ni/ZrO2 catalyst under realistic conditions at 750 °C, reproducing the conditions used for a conventional dynamic microreactor for the DRM reaction. The setup includes a gas distribution system that can be fully remotely operated. The reaction cell offers the possibility of transmission and fluorescence detection modes. The complete setup dedicated to the study of catalysts is permanently installed on the Collaborating Research Groups French Absorption spectroscopy beamline in Material and Environmental sciences (CRG-FAME) and French Absorption spectroscopy beamline in Material and Environmental sciences at Ultra-High Dilution (FAME-UHD) beamlines (BM30B and BM16) at the European Synchrotron Radiation Facility in Grenoble, France.

Fenton-like degradation of Methylene Blue using paper mill sludge-derived magnetically separable heterogeneous catalyst: Characterization and mechanism.

PubMed

Zhou, Guoqiang; Chen, Ziwen; Fang, Fei; He, Yuefeng; Sun, Haili; Shi, Huixiang

2015-09-01

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst (PMS-Fe-380) was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmet-Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue (MB). The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover, leaching tests indicated that the leached iron is negligible (<0.5mg/L). This study provides an alternative environmentally friendly reuse method for paper mill sludge and a novel catalyst PMS-Fe-380 that can be considered as a promising heterogeneous Fenton-like catalyst. Copyright © 2015. Published by Elsevier B.V.

Production of hydrocarbon fuels from pyrolysis of soybean oils using a basic catalyst.

PubMed

Xu, Junming; Jiang, Jianchun; Sun, Yunjuan; Chen, Jie

2010-12-01

Triglycerides obtained from animals and plants have attracted great attention from researchers for developing an environmental friendly and high-quality fuel, free of nitrogen and sulfur. In the present work, the production of biofuel by catalytic cracking of soybean oil over a basic catalyst in a continuous pyrolysis reactor at atmospheric pressure has been studied. Experiments were designed to study the effect of different types of catalysts on the yield and acid value of the diesel and gasoline fractions from the pyrolytic oil. It was found that basic catalyst gave a product with relatively low acid number. These pyrolytic oils were also further reacted with alcohol in order to decrease their acid value. After esterification, the physico-chemical properties of these biofuels were characterized, and compared with Chinese specifications for conventional diesel fuels. The results showed that esterification of pyrolytic oil from triglycerides represents an alternative technique for producing biofuels from soybean oils with characteristics similar to those of petroleum fuels. Published by Elsevier Ltd.

Measurement of regulated and unregulated exhaust emissions from a lawn mower with and without an oxidizing catalyst: a comparison of two different fuels.

PubMed

Christensen, A; Westerholm, R; Almén, J

2001-06-01

Relatively few emission characterization studies have been made on small engines used in garden equipment. The present investigation focuses on exhaust characterization from a lawn mower engine fueled with two different fuels in combination with and without an oxidizing catalyst. The compounds measured in the exhaust are carbon monoxide, hydrocarbons, nitrogen oxides, particulates, polycyclic aromatic hydrocarbons, methane, ethane, ethene, ethanol, and nitrous oxide. A significant reduction can be achieved by the use of a catalyst. By selection of the fuel, a significant reduction of certain carcinogenic compounds ("probably carcinogenic to humans" according to the IARC; benzo[a]pyrene and benzo[a]anthracene) may be achieved. The highest reduction improvement is achieved through the combination of an environmentally improved fuel, i.e., alkylate fuel, and a catalyst system. The data presented show that emissions from lawn mower engines are still relatively large although there is the potential for further improvements.

Catalytic dehydrogenation of isobutane in the presence of hydrogen over Cs-modified Ni2P supported on active carbon

NASA Astrophysics Data System (ADS)

Xu, Yanli; Sang, Huanxin; Wang, Kang; Wang, Xitao

2014-10-01

In this article, an environmentally friendly non-noble-metal class of Cs-Ni2P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H2-temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni2P particles, which decreases the strength of Nisbnd C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni2P/AC catalysts display much higher catalytic performance as compared to Ni2P/AC catalyst. Cs-Ni2P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni2P particles, transfer electron from Cs to Ni, and decrease acid site number and strength.

Development of HAN-based Liquid Propellant Thruster

NASA Astrophysics Data System (ADS)

Hisatsune, K.; Izumi, J.; Tsutaya, H.; Furukawa, K.

2004-10-01

Many of propellants that are applied to the conventional spacecraft propulsion system are toxic propellants. Because of its toxicity, considering the environmental pollution or safety on handling, it will be necessary to apply the "green" propellant to the spacecraft propulsion system. The purpose of this study is to apply HAN based liquid propellant (LP1846) to mono propellant thruster. Compared to the hydrazine that is used in conventional mono propellant thruster, HAN based propellant is not only lower toxic but also can obtain higher specific impulse. Moreover, HAN based propellant can be decomposed by the catalyst. It means there are the possibility of applying to the mono propellant thruster that can leads to the high reliability of the propulsion system.[1],[2] However, there are two technical subjects, to apply HAN based propellant to the mono propellant thruster. One is the high combustion temperature. The catalyst will be damaged under high temperature condition. The other is the low catalytic activity. It is the serious problem on application of HAN based propellant to the mono propellant thruster that is used for attitude control of spacecraft. To improve the catalytic activity of HAN based propellant, it is necessary to screen the best catalyst for HAN based propellant. The adsorption analysis is conducted by Monte Carlo Simulation to screen the catalyst metal for HAN and TEAN. The result of analysis shows the Iridium is the best catalyst metal for HAN and TEAN. Iridium is the catalyst metal that is used at conventional mono propellant thruster catalyst Shell405. Then, to confirm the result of analysis, the reaction test about catalyst is conducted. The result of this test is the same as the result of adsorption analysis. That means the adsorption analysis is effective in screening the catalyst metal. At the evaluating test, the various types of carrier of catalyst are also compared to Shell 405 to improve catalytic activity. The test result shows the inorganic porous media is superior to Shell405 in catalytic activity. Next, the catalyst life with HAN based propellant (LP1846) is evaluated. The Shell405 and inorganic porous media catalyst are compared at the life test. The test result shows the inorganic porous media catalyst is superior to Shell405 in catalyst life. In this paper, the detail of the result of adsorption analysis and evaluating test are reported.

An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core

EPA Science Inventory

Silver nanoparticles have antibacterial properties but their use has been a cause for concern because they persist in the environment. Here we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green a...

Integrating walnut and other hardwoods into agroforestry practices

Treesearch

Shibu. Jose

2013-01-01

Agroforestry systems have been proposed as alternative, environmentally benign systems for agricultural production in temperate North America. Walnut and other hardwoods have been successfully integrated in most agroforestry practices include alley cropping, silvopastural, windbreaks, and riparian buffers. Because of walnuts relatively thin crowns and nut production,...

Electricity from Sunlight: The Future of Photovoltaics. Worldwatch Paper 52.

ERIC Educational Resources Information Center

Flavin, Christopher

Solar photovoltaic cells have been called the ultimate energy technology, environmentally benign and without moving parts, solar cells directly convert sunlight into electricity. Photovoltaic energy conversion is fundamentally different from all other forms of electricity generation. Without turbines, generators or other mechanical equipment, it…

Preparation and characterization of a novel micro- and nanocomposite hydrogels containing cellulosic fibrils

USDA-ARS?s Scientific Manuscript database

In recent years, the preparation of cellulosic composites and nanocomposites has become an important approach because of the wide abundance of cellulose, its biodegradability, renewability, and the ability to effectively reinforce a polymer matrix in an environmentally benign nature. The main object...

BRAIN MICROGLIA (BV2) RESPONSE TO NON-PHOTOACTIVATED TIO2 NANOPARTICLES: IMPLICATIONS FOR NANOPARTICLE NEUROTOXICITY.

EPA Science Inventory

Engineered nanoparticles are attractive for use in medical, industrial, and military sectors, but little is known of their interactions with biological systems. Recent studies indicate that some are not completely benign to biological and environmental targets. Here, the respon...

Biosynthesis of Pd-Au alloys on carbon fiber paper: Towards an eco-friendly solution for catalysts fabrication

NASA Astrophysics Data System (ADS)

Zhuang, Zechao; Wang, Feifeng; Naidu, Ravendra; Chen, Zuliang

2015-09-01

Bimetallic nanomaterials with enhanced activity and stability have been extensively studied as emerging catalysts for hydrogen evolution reaction (HER). Expensive and environmentally unfriendly chemical synthesis routes inhibit their large-scale applications. In this work, we developed a facile and green synthesis of Pd-Au alloy nanoparticles (NPs) dispersed on carbon fiber paper (CFP) by plant-mediated bioreduction coupled with self-assembly. Engineering the morphology and composition of bimetallic catalysts synthesized by plant extracts on complex substrate is achieved. The resulting NPs are uniform in shape and have a spherical morphology with an average diameter of ∼180 nm, in which the molar ratio of Au/Pd is near 75:25 and the catalysts loading is about 0.5 mg cm-2. The Pd-Au/CFP hybrid electrode exhibits an excellent HER performance with a Tafel slope of 47 mV dec-1 and an exchange current density of 0.256 mA cm-2. Electrochemical stability tests through long-term potential cycles and potentiostatic electrolysis further confirm the high durability of the electrode. This development offers an efficient and eco-friendly catalysts synthesis route for constructing water-splitting cells and other electrocatalytic devices.

Facile preparation of three-dimensional Co1-xS/sulfur and nitrogen-codoped graphene/carbon foam for highly efficient oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Liang, Hui; Li, Chenwei; Chen, Tao; Cui, Liang; Han, Jingrui; Peng, Zhi; Liu, Jingquan

2018-02-01

Because of the urgent need for renewable resources, oxygen reduction reaction (ORR) has been widely studied. Finding efficient and low cost non-precious metal catalyst is increasingly critical. In this study, melamine foam is used as template to obtain porous sulfur and nitrogen-codoped graphene/carbon foam with uniformly distributed cobalt sulfide nanoparticles (Co1-xS/SNG/CF) which is prepared by a simple infiltration-drying-sulfuration method. It is noteworthy that melamine foam not only works as a three-dimensional support skeleton, but also provides a nitrogen source without any environmental pollution. Such Co1-xS/SNG/CF catalyst shows excellent oxygen reduction catalytic performance with an onset potential of only 0.99 V, which is the same as that of Pt/C catalyst (Eonset = 0.99 V). Furthermore, the stability and methanol tolerance of Co1-xS/SNG/CF are more outstanding than those of Pt/C catalyst. Our work manifests a facile method to prepare S and N-codoped 3D graphene network decorated with Co1-xS nanoparticles, which may be utilized as potential alternative to the expensive Pt/C catalysts toward ORR.

Application of the ultrasound in the mild synthesis of substituted 2,3-dihydroquinazolin-4(1H)-ones catalyzed by heterogeneous metal-MWCNTs nanocomposites

NASA Astrophysics Data System (ADS)

Safari, Javad; Gandomi-Ravandi, Soheila

2014-08-01

A practical method were applied successfully to synthesize mono- and disubstituted dihydroquinazolinones through three-component condensation of isatoic anhydride, primary amines or ammonium acetate with aromatic aldehydes in the presence of some transition metals-multi-walled carbon nanotubes under sonication. Also, metals supported on MWCNTs showed excellent catalytic performance for above-mentioned condensation. This methodology provides general, easy and efficient approach to afford the corresponding aryl substituted quinazolinone derivatives using mentioned nanocomposites as catalyst under sonication in excellent yields. The advantages of present protocol are convenient reaction, simple work-up, greenness, energy efficiency and reusable catalyst as well as mild reaction conditions. The employed metal-MWCNTs catalysts are heterogeneous and recyclable, that make the process more environmentally friendly.

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

Wang, Xiang; Shi, Hui; Szanyi, János

Catalytic CO2 conversion to energy carriers and intermediates is of utmost importance to energy and environmental goals. However, the lack of fundamental understanding of the reaction mechanism renders designing a selective catalyst inefficient. We performed operando FTIR/SSITKA experiments to understand the correlation between the kinetics of product formation and that of surface species conversion during CO2 reduction over Pd/Al2O3 catalysts. We found that the rate-determining step for CO formation is the conversion of adsorbed formate, while that for CH4 formation is the hydrogenation of adsorbed carbonyl. The balance of the hydrogenation kinetics between adsorbed formates and carbonyls governs the selectivitiesmore » to CH4 and CO. We demonstrated how this knowledge can be used to design catalysts to achieve high selectivities to desired products.« less

Cumulative effect of transition metals on nitrogen and fluorine co-doped graphite nanofibers: an efficient and highly durable non-precious metal catalyst for the oxygen reduction reaction.

PubMed

Peera, S Gouse; Arunchander, A; Sahu, A K

2016-08-14

Nitrogen and fluorine co-doped graphite nanofibers (N/F-GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe-Co/NF-GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe-Co/NF-GNF catalyst compared to the simple N/F-GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe-Co/NF-GNF catalyst also exhibits complete tolerance to CH3OH and CO. The Fe-Co/NF-GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe-Co/NF-GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe-Co/NF-GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe-Co/NF-GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M-N-C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity and long term durability of the Fe-Co/NF-GNF catalyst make it a promising ORR electrocatalyst for the fuel cell cathode reaction.

Environmental Application, Fate, Effects, and Concerns of Ionic Liquids: A Review.

PubMed

Amde, Meseret; Liu, Jing-Fu; Pang, Long

2015-11-03

Ionic liquids (ILs) comprise mostly of organic salts with negligible vapor pressure and low flammability that are proposed as replacements for volatile solvents. ILs have been promoted as "green" solvents and widely investigated for their various applications. Although the utility of these chemicals is unquestionable, their toxic effects have attracted great attention. In order to manage their potential hazards and design environmentally benign ILs, understanding their environmental behavior, fate and effects is important. In this review, environmentally relevant issues of ILs, including their environmental application, environmental behavior and toxicity are addressed. In addition, also presented are the influence of ILs on the environmental fate and toxicity of other coexisting contaminants, important routes for designing nontoxic ILs and the techniques that might be adopted for the removal of ILs.

2,2,2-Trifluoroacetophenone as an organocatalyst for the oxidation of tertiary amines and azines to N-oxides.

PubMed

Limnios, Dimitris; Kokotos, Christoforos G

2014-01-07

A cheap, mild and environmentally friendly oxidation of tertiary amines and azines to the corresponding N-oxides is reported by using polyfluoroalkyl ketones as efficient organocatalysts. 2,2,2-Trifluoroacetophenone was identified as the optimum catalyst for the oxidation of aliphatic tertiary amines and azines. This oxidation is chemoselective and proceeds in high-to-quantitative yields utilizing 10 mol % of the catalyst and H2 O2 as the oxidant. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CO2 methanation on the catalyst of Ni/MCM-41 promoted with CeO2.

PubMed

Wang, Xiaoliu; Zhu, Lingjun; Liu, Yincong; Wang, Shurong

2018-06-01

CO 2 as a raw feed combined with renewable hydrogen for the production of useful chemicals and alternative energy products is one of the solutions to environmental and energy problems. In this study, a series of Ni-xCeO 2 /MCM-41 catalysts with a nickel content of 20wt% were prepared through deposition precipitation method for CO 2 methanation. Different characterization methods, including BET, XRD, TEM, SEM, H 2 -TPR and H 2 -TPD were applied to help explore the influence mechanism of CeO 2 on Ni/MCM-41 in CO 2 methanation. It was found that all CeO 2 -promoted catalysts exhibited enhanced catalytic activity when compared to Ni/MCM-41. The catalyst modified with 20wt% CeO 2 showed the best catalytic performance, with CO 2 conversion and CH 4 selectivity of 85.6% and 99.8%, respectively, at the temperature of 380°C under atmospheric pressure. The synergetic effects among Ni 0 active sites, the promoter and the support, including nickel dispersion improvement and increased CO 2 adsorption sites due to the addition of CeO 2 , were considered as important factors for high reactivity of the promoted catalysts. The stability test showed that the promoted catalyst maintained its high reactivity after 30h. Copyright © 2017 Elsevier B.V. All rights reserved.

Recycling evaluation of new-generation environmentally benign pressure sensitive adhesives

Treesearch

Said M. Abubakr; Carl Houtman; Dave Bormett; Nancy Ross Sutherland; Joe Peng

1999-01-01

As a result of a United States Postal Service (USPS) initiative, a work team was formed consisting of representatives from USPS, Forest Products Laboratory (FPL), Specialized Technology Resources, Inc. (STR), and industry. The industries represented included papermakers, paper recyclers, paper collectors, equipment manufacturers, paper users, adhesive manufacturers and...

Promising Properties and System Demonstration of an Environmentally Benign Yellow Smoke Formulation for Hand-Held Signals

DTIC Science & Technology

2014-04-18

differences between the current specification and this new baseline configuration: (1) The tube is now composed of cardboard instead of stainless steel ...version of this previously reported composition, one without fumed silica hereafter referred to as formulation A. This formulation consists of Solvent

Green application of flame retardant cotton fabric using supercritical carbon dioxide

USDA-ARS?s Scientific Manuscript database

Due to its environmentally benign character, supercritical carbon dioxide (scCO2) is considered in green chemistry as a substitute for organic solvents in chemical reactions. In this poster, an innovative approach for preparation of flame retardant woven and nonwoven fabrics were obtained by utiliz...

Supercritical carbon dioxide fractionation of whey protein isolate for new food-grade ingredients

USDA-ARS?s Scientific Manuscript database

A new, environmentally benign whey protein fractionation process was developed using supercritical CO2 (SCO2) as an acid aggregating agent to separate a-lactalbumin (a-LA) aggregates from soluble beta-lactoglobulin (beta-LG) protein in concentrated whey protein isolate (WPI) solutions. The process e...

Back to the future? Tourism, place, and sustainability

Treesearch

Daniel R. Williams; Susan Van Patten

1998-01-01

Tourism, especially rural tourism, epitomizes the problematic elements of sustainability. On the one hand, as a service industry trading on the uniqueness of a place and region, tourism is seen as more environmentally benign than industrial production, manufacturing, extractive industries, and even agriculture. When traditional resource dependent industries decline (...

Hydrogen Production and Delivery | Hydrogen and Fuel Cells | Hydrogen and

Science.gov Websites

degrees Celsius. Ultra-high temperatures are required for thermochemical reaction cycles to produce for the environmentally benign production of hydrogen. Very high reaction rates at these elevated temperatures give rise to very fast reaction rates, which significantly enhance production rates and more than

Promising flame retardant textile in supercritical carbon dioxide

USDA-ARS?s Scientific Manuscript database

Since carbon dioxide is non-toxic, non-flammable and cost-effective, supercritical carbon dioxide (scCO2) is widely used in textile dyeing applications. Due to its environmentally benign character, scCO2 is considered in green chemistry as a substitute for organic solvents in chemical reactions. O...

POM-assisted electrochemical delignification and bleaching of chemical pulp

Treesearch

Helene Laroche; Mohini Sain; Carl Houtman; Claude Daneault

2001-01-01

A polyoxometalate-catalyzed electrochemical process has shown good selectivity in delignifying pulp. This breakthrough in redox catalysis shows promise for the development of a new environmentally benign technology for pulp bleaching. The electrochemical process, applied with a mildly alkaline electrolyte solution containing trace amounts of a vanadium-based...

Financial and Economic Analysis of Reduced Impact Logging

Treesearch

Tom Holmes

2016-01-01

Concern regarding extensive damage to tropical forests resulting from logging increased dramatically after World War II when mechanized logging systems developed in industrialized countries were deployed in the tropics. As a consequence, tropical foresters began developing logging procedures that were more environmentally benign, and by the 1990s, these practices began...

Environmentally benign USPS stamps : baseline pilot recycling results

Treesearch

D. F. Seiter; M. A. Pikulin; R. G. Meese; Said M. Abubakr; David Bormett; Nancy Ross-Sutherland

1998-01-01

Stickies continue to represent the most challenging contaminant to remove from recycled secondary fiber. Current projections suggest that pressure sensitive adhesive (PSA) markets will continue to grow rapidly, increasing the concentration of these contaminants in common office-pack wastepaper. PSAas reformulated to exhibit higher removal efficiencies within standard...

Non-Leaching, Benign, Fouling Control, Multilayer Polymer Coatings for Marine Applications: PP-1274 Findings

DTIC Science & Technology

2003-09-01

transition temperature TBT tributyltin THF tetrahydrofuran TPE thermoplastic elastomer 4 EXECUTIVE SUMMARY The goal of this research is to...compounds that are environmentally persistant cause damage to the ecosystem, and enter the food chain. The ban on tributyltin ( TBT ) antifoulants by the

Synthesis of silver nanoparticles in textile finish aqueous system and their antimicrobial properties on cotton fibers

USDA-ARS?s Scientific Manuscript database

Silver nanoparticles (NPs) were synthesized by a simple and environmentally benign procedure using poly (ethylene glycol) (PEG) as reducing agent and stabilizer in the textile finish aqueous system, and their antimicrobial properties on greige (mechanically cleaned) and bleached cotton fibers were i...

A new V-doped Bi2(O,S)3 oxysulfide catalyst for highly efficient catalytic reduction of 2-nitroaniline and organic dyes.

PubMed

Abay, Angaw Kelemework; Kuo, Dong-Hau; Chen, Xiaoyun; Saragih, Albert Daniel

2017-12-01

A new type of convenient, and environmentally friendly, Vanadium (V)-doped Bi 2 (O,S) 3 oxysulfide catalyst with different V contents was successfully synthesized via a simple and facile method. The obtained V-doped Bi 2 (O,S) 3 solid solution catalysts were fully characterized by conventional methods. The catalytic performance of the samples was tested by using the reduction of 2-nitroaniline (2-NA) in aqueous solution. The reduction/decolorization of methylene blue (MB) and rhodamine B (RhB) was also chosen to evaluate the universality of catalysts. It was observed that the introduction of V can improve the catalytic performance, and 20%V-Bi 2 (O,S) 3 was found to be the optimal V doping concentration for the reduction of 2-NA, MB, and RhB dyes. For comparative purposes, a related V-free Bi 2 (O, S) 3 oxysulfide material was synthesized and tested as the catalyst. The superior activity of V-doped Bi 2 (O,S) 3 over pure Bi 2 (O,S) 3 was ascribed mainly to an increase in active sites of the material and also due to the presence of synergistic effects. The presence of V 5+ as found from XPS analysis may interact with Bi atoms and enhancing the catalytic activity of the sample. In the catalytic reduction of 2-NA, MB and RhB, the obtained V-doped Bi 2 (O,S) 3 oxysulfide catalyst exhibited excellent catalytic activity as compared with other reported catalysts. Furthermore this highly efficient, low-cost and easily reusable V-doped Bi 2 (O,S) 3 catalyst is anticipated to be of great potential in catalysis in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

NO oxidation on Zeolite Supported Cu Catalysts: Formation and Reactivity of Surface Nitrates

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

Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton

2016-04-18

The comparative activities of a small-pore Cu-CHA and a large-pore Cu-BEA catalyst for the selective catalytic reduction (SCR) of NOx with NH3, and for the oxidation of NO to NO2 and the subsequent formation of surface nitrates were investigated. Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity. Furthermore, Cu-CHA is even less active than Cu-BEA in catalyzing NO oxidation but is clearly more active for SCR reactions. Temperature-programed desorption (TPD) experiments following the adsorption of (NO2 + NO + O2) with different NO2:NO ratios reveal that the poor NO oxidation activity ofmore » the two catalysts is not due to the formation of stable surface nitrates. On the contrary, NO is found to reduce and decompose the surface nitrates on both catalysts. To monitor the reaction pathways, isotope exchange experiments were conducted by using 15NO to react with 14N-nitrate covered catalyst surfaces. The evolution of FTIR spectra during the isotope exchange process demonstrates that 14N-nitrates are simply displaced with no formation of 15N-nitrates on the Cu-CHA sample, which is clearly different from that observed on the Cu-BEA sample where formation of 15N-nitrates is apparent. The results suggest that the formal oxidation state of N during the NO oxidation on Cu-CHA mainly proceeds from its original +2 to a +3 oxidation state, whereas reaching a higher oxidation state for N, such as +4 or +5, is possible on Cu-BEA. The authors at PNNL gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less

Earth Observation from Space - The Issue of Environmental Sustainability

NASA Technical Reports Server (NTRS)

Durrieu, Sylvie; Nelson, Ross F.

2013-01-01

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following: 1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions. 2. Space launches are benign with respect to environmental impacts. 3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change. 4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space. 5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products. At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of thedata acquisition step,which is at the very beginning of the information streamleading to decision and action, will enhance coherence in the information streamand strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions inthe contextof sustainablemanagementof Earth's resources. Takingeachassumptioninturn,we find the following: (1) Space debris may limit access to Low Earth Orbit over the next decades. (2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products. (3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied. (4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest. (5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies e e.g. NASA, ESA, CNES e it seems prudent to combine resources.

Spatial and temporal age-related spectral alterations in benign human breast tissue

NASA Astrophysics Data System (ADS)

Theophilou, Georgios; Fogarty, Simon W.; Trevisan, Júlio; Strong, Rebecca J.; Heys, Kelly A.; Patel, Imran I.; Stringfellow, Helen F.; Martin-Hirsch, Pierre L.; Martin, Francis L.

2016-02-01

Epidemiological evidence suggests that cancers attributable to exogenous carcinogenic agents may appear decades after initiating exposures. Environmental factors including lifestyle and/or diet have been implicated in the aetiology of breast cancer. Breast tissue undergoes continuous molecular and morphological changes from the time of thelarche to menopause and thereafter. These alterations are both cyclical and longitudinal, and can be influenced by several environmental factors including exposure to oestrogens. Research into the latent period leading to breast carcinogenesis has been mostly limited to when hyperplastic lesions are present. Investigations to identify a biomarker of commitment to disease in normal breast tissue are hindered by the molecular and histological diversity of disease-free breast tissue. Benign tissue from reduction mammoplasties provides an opportunity to study biochemical differences between women of similar ages as well as alterations with advancing age. Herein, synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy was used to examine the terminal ductal lobular epithelium (TDLU) and, intra- and inter-lobular epithelium to identify spatial and temporal changes within these areas. Principal component analysis (PCA) followed by linear discriminant analysis of mid-infrared spectra revealed unambiguous inter-individual as well as age-related differences in each histological compartment interrogated. Moreover, exploratory PCA of luminal and myoepithelial cells within the TDLU indicated the presence of specific cells, potentially stem cells. Understanding alterations within benign tissue may assist in the identification of alterations in latent pre-clinical stages of breast cancer.

Critical design of heterogeneous catalysts for biomass valorization: current thrust and emerging prospects

DOE PAGES

De, Sudipta; Dutta, Saikat; Saha, Basudeb

2016-01-01

Catalysis in the heterogeneous phase plays a crucial role in the valorization of biorenewable substrates with controlled reactivity, efficient mechanical process separation, greater recyclability and minimization of environmental effects.

Anti-site defected MoS2 sheet-based single electron transistor as a gas sensor

NASA Astrophysics Data System (ADS)

Sharma, Archana; Husain, Mushahid; Srivastava, Anurag; Khan, Mohd. Shahid

2018-05-01

To prevent harmful and poisonous CO gas molecules, catalysts are needed for converting them into benign substances. Density functional theory (DFT) calculations have been used to study the adsorption of CO and CO2 gas molecules on the surface of MoS2 monolayer with Mo atom embedded at S-vacancy site (MoS). The strong interaction between Mo metal with pristine MoS2 sheet suggests its strong binding nature. Doping Mo into MoS2 sheet enhances CO and CO2 adsorption strength. The sensing response of MoS-doped MoS2 system to CO and CO2 gas molecules is obtained in the single electron transistor (SET) environment by varying bias voltage. Doping reduces charging energy of the device which results in fast switching of the device from OFF to ON state.

Polymer- and dendrimer-coated magnetic nanoparticles as versatile supports for catalysts, scavengers, and reagents.

PubMed

Kainz, Quirin M; Reiser, Oliver

2014-02-18

The work-up of chemical reactions by standard techniques is often time consuming and energy demanding, especially when chemists have to guarantee low levels of metal contamination in the products. Therefore, scientists need new ideas to rapidly purify reaction mixtures that are both economically and environmentally benign. One intriguing approach is to tether functionalities that are required to perform organic reactions to magnetic nanoparticles, for example, catalysts, reagents, scavengers, or chelators. This strategy allows researchers to quickly separate active agents from reaction mixtures by exploiting the magnetic properties of the support. In this Account, we discuss the main attributes of magnetic supports and describe how we can make the different nanomagnets accessible by surface functionalization. Arguably the most prominent magnetic nanoparticles are superparamagnetic iron oxide nanoparticles (SPIONs) due to their biologically well-accepted constituents, their established size-selective synthesis methods, and their diminished agglomeration (no residual magnetic attraction in the absence of an external magnetic field). However, nanoparticles made of pure metal have a considerably higher magnetization level that is useful in applications where high loadings are needed. A few layers of carbon can efficiently shield such highly reactive metal nanoparticles and, equally important, enable facile covalent functionalization via diazonium chemistry or non-covalent functionalization through π-π interactions. We highlight carbon-coated cobalt (Co/C) and iron (Fe/C) nanoparticles in this Account and compare them to SPIONs stabilized with surfactants or silica shells. The graphene-like coating of these nanoparticles offers only low loadings with functional groups via direct surface modification, and the resulting nanomagnets are prone to agglomeration without effective steric stabilization. To overcome these restrictions and to tune the dispersibility of the magnetic supports in different solvents, we can introduce dendrimers and polymers on Co/C and Fe/C platforms by various synthetic strategies. While dendrimers have the advantage of being able to array all functional groups on the surface, polymers need fewer synthetic steps and higher molecular weight analogues are easily accessible. We present the application of these promising hybrid materials for the extraction of analytes or contaminates from complex aqueous solutions (e.g. waste water treatments or blood analytics), for metal-, organo-, and biocatalysis, and in organic synthesis. In addition, we describe advanced concepts like magnetic protecting groups, a multistep synthesis solely applying magnetic reagents and scavengers, and thermoresponsive self-separating magnetic catalysts. We also discuss the first examples of the use of magnetic scaffolds manipulated by external magnetic fields in flow reactors on the laboratory scale. These hold promise for future applications of magnetic hybrid materials in continuous flow or highly parallelized syntheses with rapid magnetic separation of the applied resins.

Fe3O4@SiO2@KIT-6 as an Efficient and Reusable Catalyst for the Synthesis of Novel Derivatives of 3,3'-((Aryl-1-phenyl-1H-pyrazol-4- yl)methylene)bis (1H-indole).

PubMed

Nikpassand, Mohammad; Fekri, Leila Zare; Nabatzadeh, Mozhdeh

2017-01-01

Korea advanced institute of science and technology cubic ordered mesoporous silica (KIT-6 mesoporous) silica coated magnetite nanoparticles, is an effective, ecobenign and recyclable catalyst for the electrophilic substitution reactions of indoles with various synthetized aldehydes to afford the corresponding novel diindolylmethanes in high yields and short reaction times. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification. The present methodology offers several advantages such as aqueous media, excellent yields, simple procedure, mild conditions and reduced environmental consequences. All of synthesized compounds are new and were characterized by IR, NMR and elemental analyses. A mixture of synthetized pyrazolecarbaldehydes [24] (2.0mmol), indole (4.0mmol) and Fe3O4@SiO2@KIT-6 (0.04mmol) and H2O (10mL) were stirred at room temperature for the required reaction time according to Table 2. After completion of the reaction, the product was solved in CHCl3 (3×10 mL) and insoluble catalyst was removed by filtration in the presence of an efficient magnetic bar. The organic phase including the product and CHCl3 was evaporated under vacuum. The resulting crude material was purified by recrystallization from EtOH to afford pure products. As part of our on interest for the development of efficient and environmentally friendly procedures for the synthesis of heterocyclic and pharmaceutical compounds, an efficient, facile and aqueous media was introduced for the synthesis of novel derivatives of diindolylmethanes containing pyrazole moiety. A variety of synthetized aldehyde compounds reacted smoothly with indoles to produce diindolylmethanes under these reaction conditions. The electron deficiency and the nature of the substituents on the aromatic ring show some effects on this conversion. All the reactions were run with catalytic amounts of catalysts. The best results gained with 0.04mmol of Fe3O4@SiO2@KIT-6 as a strong Lewis acid at room temperature in aqueous media. In conclusion, we have investigated the synthesized KIT-6 mesoporous silica coated magnetite nanoparticles (MMNPs) as a mild and efficient catalyst for the synthesis of novel diindolylmethanes coupled with pyrazole moiety in aqua media. The simplicity, easy workup together with the use of inexpensive, environmentally friendly and reusable catalyst, is the notable features of this catalytic procedure. To the best of our knowledge, this is the first report for the synthesis of a new library of diindolylmethane compound bearing pyrazole moiety that enhance the biological and pharmacological activity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Nanomaterials and Global Sustainability.

PubMed

Hamers, Robert J

2017-03-21

Nanomaterials provide tremendous opportunities to advance human welfare in many areas including energy storage, catalysis, photovoltaic energy conversion, environmental remediation, and agriculture. As nanomaterials become incorporated into commercial processes and consumer products in increasing amounts, it will be essential to develop an understanding of how these materials interact with the environment. The broad spectrum and complexity of nanomaterials drive a need for molecular-level design rules. Ultimately a grand challenge is to use the power of chemistry to ensure that nanoenabled technologies can come to fruition in an environmentally benign manner.

Removal of halogenated emerging contaminants from water by nitrogen-doped graphene decorated with palladium nanoparticles: Experimental investigation and theoretical analysis.

PubMed

Li, Lei; Gong, Li; Wang, Yi-Xuan; Liu, Qi; Zhang, Jie; Mu, Yang; Yu, Han-Qing

2016-07-01

The removal performance and mechanisms of halogenated emerging contaminants from water by palladium decorated nitrogen-doped graphene (Pd/NG) were investigated in this study. For comparison, three catalysts of Pd/NG, palladium decorated graphene (Pd/G) and commercial Pd/C were initially explored to degrade tetrabromobisphenol A (TBBPA). After that, the influence of various environmental parameters on TBBPA removal by the Pd/NG catalyst was evaluated. Moreover, both Langmuir-Hinshelwood model and density functional theory (DFT) were adopted to theoretically elucidate the adsorption and the activation of TBBPA on the catalyst. The results show that the apparent rate constant of TBBPA dehalogenation was increased by 26.7% and 39.0% in the presence of the Pd/NG catalyst compared to the Pd/G and Pd/C ones. Higher temperature, catalyst dosage and alkaline conditions resulted in the enhancement of TBBPA dehalogenation by the Pd/NG catalyst, while humic acid in the solution had a negatively effect on the transformation of TBBPA. The corresponding rate constant value exhibited a 2.1- and 1.8-fold increase with the rise of temperature from 298 to 328 K and initial pH from 6.5 to 9.0, respectively. On the contrary, the rate constant was decreased by 78.9% in the presence of 15 mg L(-1) humic acid. Theoretical analysis revealed that both adsorption and activation processes of TBBPA on the Pd/NG catalyst were enhanced through the N doping into graphene framework. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous production of oil enriched in ω-3 polyunsaturated fatty acids and biodiesel from fish wastes.

PubMed

Enascuta, Cristina Emanuela; Stepan, Emil; Bolocan, Ion; Bombos, Dorin; Calin, Catalina; Oprescu, Elena-Emilia; Lavric, Vasile

2018-05-01

The waste resulted from fish processing industries are discarded into the environment around the world, causing environmental pollution. The main problem of fish oil extracted from waste is the high content in free fatty acids (FFA) which decrease the yield in fatty acids esters during transesterification reactions. Therefore, to correct the fish-oil properties, a new environmentally friendly heterogeneous superacid catalyst (SO 4 2- /SnO 2 -ZrO 2 ) was tested in the esterification reaction of FFA with ethanol. The catalyst was characterized by different techniques (XRD, FT-IR, FT-IR of adsorbed pyridine, BET, SEM-EDX, TGA and acidity measurements). The reaction was found to follow a Langmuir-Hinshelwood (L-H) dual-site mechanism with the novelty that both Brönsted and Lewis acid centers participate equally in the esterification reaction. The pre-treated oil was subjected to transesterification reaction with ethanol over a heterogeneous base catalyst and then, the saturated and unsaturated fractions of fatty acid ethyl esters (FAEE) were separated using a vacuum rectification unit with falling film. The saturated content can be used as biofuel, while the unsaturated FAEE are further transesterified with glycerol in order to obtain oil with high content in polyunsaturated fatty acids (PUFA). A detailed study of the intrinsic kinetic process at the surface of the superacid catalyst and a thorough mathematical model of the fixed bed reactor were written and validated by an experimental program, designed according to the D-optimal methodology. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mesoporous Phosphorus-Doped g-C3N4 Nanostructured Flowers with Superior Photocatalytic Hydrogen Evolution Performance.

PubMed

Zhu, Yun-Pei; Ren, Tie-Zhen; Yuan, Zhong-Yong

2015-08-05

Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

Role of modern chemistry in sustainable arable crop protection.

PubMed

Smith, Keith; Evans, David A; El-Hiti, Gamal A

2008-02-12

Organic chemistry has been, and for the foreseeable future will remain, vitally important for crop protection. Control of fungal pathogens, insect pests and weeds is crucial to enhanced food provision. As world population continues to grow, it is timely to assess the current situation, anticipate future challenges and consider how new chemistry may help meet those challenges. In future, agriculture will increasingly be expected to provide not only food and feed, but also crops for conversion into renewable fuels and chemical feedstocks. This will further increase the demand for higher crop yields per unit area, requiring chemicals used in crop production to be even more sophisticated. In order to contribute to programmes of integrated crop management, there is a requirement for chemicals to display high specificity, demonstrate benign environmental and toxicological profiles, and be biodegradable. It will also be necessary to improve production of those chemicals, because waste generated by the production process mitigates the overall benefit. Three aspects are considered in this review: advances in the discovery process for new molecules for sustainable crop protection, including tests for environmental and toxicological properties as well as biological activity; advances in synthetic chemistry that may offer efficient and environmentally benign manufacturing processes for modern crop protection chemicals; and issues related to energy use and production through agriculture.

Polysaccharide-thickened aqueous fluoride solutions for rapid destruction of the nerve agent VX. Introducing the opportunity for extensive decontamination scenarios.

PubMed

Elias, Shlomi; Saphier, Sigal; Columbus, Ishay; Zafrani, Yossi

2014-01-01

Among the chemical warfare agents, the extremely toxic nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is a target of high importance in the development of decontamination methods, due to its indefinite persistence on common environmental surfaces. Liquid decontaminants are mostly characterized by high corrosivity, usually offer poor coverage, and tend to flow and accumulate in low areas. Therefore, the development of a noncorrosive decontaminant, sufficiently viscous to resist dripping from the contaminated surface, is necessary. In the present paper we studied different polysaccharides-thickened fluoride aqueous solutions as noncorrosive decontaminants for rapid and efficient VX degradation to the nontoxic product EMPA (ethyl methylphosphonic acid). Polysaccharides are environmentally benign, natural, and inexpensive. Other known decontaminants cannot be thickened by polysaccharides, due to the sensitivity of the latter toward basic or oxidizing agents. We found that the efficiency of VX degradation in these viscous solutions in terms of kinetics and product identity is similar to that of KF aqueous solutions. Guar gum (1.5 wt %) with 4 wt % KF was chosen for further evaluation. The benign nature, rheological properties, adhering capabilities to different surfaces, and decontamination from a porous matrix were examined. This formulation showed promising properties for implementation as a spray decontaminant for common and sensitive environmental surfaces.

Impact of different catalysis supported by oyster shells on the pyrolysis of tyre wastes in a single and a double fixed bed reactor.

PubMed

Kordoghli, Sana; Khiari, Besma; Paraschiv, Maria; Zagrouba, Fethi; Tazerout, Mohand

2017-09-01

The treatment and disposal of tyres from vehicles has long been of considerable environmental importance. Studies have been undertaken to reduce their environmental impact. In this study, an alternative gas was produced from automobile tyre wastes by the means of a controlled pyrolysis. To do so, a novel catalytic system was designed with the aim of increasing the rate of conversion and improving the quality of the pyrolysis products. This work aimed also to reduce the severity of the overall reactions, by using powder catalysts (MgO, Al 2 O 3 , CaCO 3 , and zeolite ZSM-5) uniformly distributed on two layers of oyster shells (OS) particles. The catalyst/tyres mass ratio was kept for all the tests at 1/30. The pyrolysis reactor was maintained at 500°C and the influence of each catalyst and of the number of shell beds (0, 1 or 2), on the yield and composition of the derived products, was examined. The gas yields could contribute by 1.2% of total consumption in Tunisia. Furthermore, some combinations could upgrade the derived gas and made it possible to use it as such or with the minimum of post-treatment. It was found that, with the use of supported catalyst, the gas produced is 45% greater compared to classical thermal pyrolysis. The Heating value of the produced gas was also improved by the use of supported catalysts; it was found 16% greater with the use of Al 2 O 3 /OS compared to non-catalytic pyrolysis. When compared to the gas obtained from only one catalytic supported bed, the sulfur content was reduced by 80% with the use of CaCO 3 /OS on two catalytic beds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural analysis of nickel doped cerium oxide catalysts for fuel reforming in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Cavendish, Rio

As world energy demands increase, research into more efficient energy production methods has become imperative. Heterogeneous catalysis and nanoscience are used to promote chemical transformations important for energy production. These concepts are important in solid oxide fuel cells (SOFCs) which have attracted attention because of their potential to provide an efficient and environmentally favorable power generation system. The SOFC is also fuel-flexible with the ability to run directly on many fuels other than hydrogen. Internal fuel reforming directly in the anode of the SOFC would greatly reduce the cost and complexity of the device. Methane is the simplest hydrocarbon and a main component in natural gas, making it useful when testing catalysts on the laboratory scale. Nickel (Ni) and gadolinium (Gd) doped ceria (CeO 2) catalysts for potential use in the SOFC anode were synthesized with a spray drying method and tested for catalytic performance using partial oxidation of methane and steam reforming. The relationships between catalytic performance and structure were then investigated using X-ray diffraction, transmission electron microscopy, and environmental transmission electron microscopy. The possibility of solid solutions, segregated phases, and surface layers of Ni were explored. Results for a 10 at.% Ni in CeO2 catalyst reveal a poor catalytic behavior while a 20 at.% Ni in CeO2 catalyst is shown to have superior activity. The inclusion of both 10 at.% Gd and 10 at.% Ni in CeO2 enhances the catalytic performance. Analysis of the presence of Ni in all 3 samples reveals Ni heterogeneity and little evidence for extensive solid solution doping. Ni is found in small domains throughout CeO2 particles. In the 20 at.% Ni sample a segregated, catalytically active NiO phase is observed. Overall, it is found that significant interaction between Ni and CeO2 occurs that could affect the synthesis and functionality of the SOFC anode.

Synthesis, characterization, nucleic acid interactions and photoluminescent properties of methaniminium hydrazone Schiff base and its Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes

NASA Astrophysics Data System (ADS)

Sennappan, M.; Murali Krishna, P.; Hosamani, Amar A.; Hari Krishna, R.

2018-07-01

An environmental benign and efficient reaction was carried out via amine exchange and condensation reaction in water and methanol mixture (3:1) and absence of catalyst between 1-[3-(2-hydroxy benzylidene)amine)phenyl]ethanone and benzhydrazide yields methaniminium hydrazone Schiff base in high yield. The prepared ligand was structurally characterized by using single crystal XRD, elemental analysis and spectroscopy (UV-Vis, FT-IR, LC-MS and NMR) techniques. The crystal data indicates the ligand crystallizes in orthorhombic system with Pna21 space group. Further, the ligand was used in synthesis of mononuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes and were characterized by elemental analysis, magnetic moment and spectroscopy (UV-Vis, FT-IR and ESR) studies. The spectral data showed that ligand is coordinated to the metal ion through azomethine nitrogen and methaniminium nitrogen. The DNA binding absorption titrations reveals that, ligand, L and its metal complexes, 1-6 are avid binders to CT- DNA. The apparent binding constant values of compounds are in the order of 106 M-1. The nuclease activity of ligand, L and its metal complexes, 1-6 were investigated by gel electrophoresis method using pUC18 DNA. The photoluminescent properties of the methaniminium hydrazone ligand, L and its various metal complexes, 1-6 were investigated. The emission spectra of both ligand (L) and metal complexes (1-6) exhibits emission in the range of blue to red.

Effect of Oxygen Defects on the Catalytic Performance of VOx/CeO2 Catalysts for Oxidative Dehydrogenation of Methanol

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

Li, Yan; Wei, Zhehao; Gao, Feng

2015-05-01

In this work, CeO2 nanocubes with controlled particle size and dominating (100) facets are synthesized as supports for VOx catalysts. Combined TEM, SEM, XRD, and Raman study reveals that the oxygen vacancy density of CeO2 supports can be tuned by tailoring the particle sizes without altering the dominating facets, where smaller particle sizes result in larger oxygen vacancy densities. At the same vanadium coverage, the VOx catalysts supported on small-sized CeO2 supports with higher oxygen defect densities exhibit promoted redox property and lower activation energy for methoxyl group decomposition, as evidenced by H2-TPR and methanol TPD study. These results furthermore » confirm that the presence of oxygen vacancies plays an important role in promoting the activity of VOx species in methanol oxidation. We gratefully acknowledge financial support from the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Part of this work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for the DOE by Battelle.« less

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

Mays, Jeff

One-step hydrogen generation, using Sorption Enhanced Reforming (SER) technology, is an innovative means of providing critical energy and environmental improvements to US manufacturing processes. The Gas Technology Institute (GTI) is developing a Compact Hydrogen Generator (CHG) process, based on SER technology, which successfully integrates previously independent process steps, achieves superior energy efficiency by lowering reaction temperatures, and provides pathways to doubling energy productivity with less environmental pollution. GTI’s prior CHG process development efforts have culminated in an operational pilot plant. During the initial pilot testing, GTI identified two operating risks- 1) catalyst coating with calcium aluminate compounds, 2) limited solidsmore » handling of the sorbent. Under this contract GTI evaluated alternative materials (one catalyst and two sorbents) to mitigate both risks. The alternate catalyst met performance targets and did not experience coating with calcium aluminate compounds of any kind. The alternate sorbent materials demonstrated viable operation, with one material enabling a three-fold increase in sorbent flow. The testing also demonstrated operation at 90% of its rated capacity. Lastly, a carbon dioxide co-production study was performed to assess the advantage of the solid phase separation of carbon dioxide- inherent in the CHG process. Approximately 70% lower capital cost is achievable compared to SMR-based hydrogen production with CO2 capture, as well as improved operating costs.« less

Exploring green catalysts for production of biofuels and value added chemicals for renewable and sustainable energy future

NASA Astrophysics Data System (ADS)

Budhi, Sridhar

Porous silica have attracted significant attention in the past few decades due to their unique textural properties. They were extensively investigated for applications in catalysis, separation, environmental remediation and drug delivery. We have investigated the porous metal incorporated silica in the synthetic as well as catalytic perspectives. The synthesis of metal incorporated mesoporous silica via co-condensation such as SBA-15, KIT-5 are still challenging as it involves acidic synthetic route. Synthesis in high acidity conditions affects the incorporation of metal in silica due to high dissolution of metal precursors and breaking of metal oxygen and silica bond. The research presented here demonstrates an efficient way to incorporate metals by addition of diammonium hydrogen phosphate along with metal precursor during the synthesis. The incorporation efficiency has increased 2-3 times with this approach. Catalytic studies were performed to support our hypothesis. Such synthesized molybdenum incorporated mesoporous silica were investigated as catalyst for fast pyrolysis. When molydenum incorporated in silica was used as catalyst for fast pyrolysis of pine, it selectively produced furans (furan, methylfuran and dimethylfuran). Furans are considered value-added chemicals and can be used as a blendstock for diesel/jet grade fuel. The catalyst was very stable to harsh pyrolysis conditions and had a longer life before deactivation when compared with traditional zeolites. Further, this catalyst did not produce aromatic hydrocarbons in significant yields unlike zeolites. The origin of the furans was determined to be biopolymer cellulose and the selectivity for furans are attributed to low catalyst acidity. The effect of silica to alumina ratio (SAR) of beta-zeolite was investigated ranging to elucidate the relationship between the of number of acid sites on product speciation and catalyst deactivation on catalysts supplied by Johnson Matthey. The catalyst with low SAR (more acid sites) produced predominantly aromatic hydrocarbons and olefins with no detectable oxygen containing species. In contrary, the catalyst with high SAR (fewer acid sites) produced a suite of oxygenated products such as furans, phenols and cresols. The coke deposited on each catalyst and the yield of aromatic hydrocarbons were in direct proportion to the number of acid sites. When catalysts were active, the biomass selectivity towards hydrocarbons and amount of coke were constant regardless of SAR.

Using elastin protein to develop highly efficient air cathodes for lithium-O2 batteries

NASA Astrophysics Data System (ADS)

Guo, Guilue; Yao, Xin; Ang, Huixiang; Tan, Huiteng; Zhang, Yu; Guo, Yuanyuan; Fong, Eileen; Yan, Qingyu

2016-01-01

Transition metal-nitrogen/carbon (M-N/C, M = Fe, Co) catalysts are synthesized using environmentally friendly histidine-tag-rich elastin protein beads, metal sulfate and water soluble carbon nanotubes followed by post-annealing and acid leaching processes. The obtained catalysts are used as cathode materials in lithium-O2 batteries. It has been discovered that during discharge, Li2O2 nanoparticles first nucleate and grow around the bead-decorated CNT regions (M-N/C centres) and coat on the catalysts at a high degree of discharge. The Fe-N/C catalyst-based cathodes deliver a capacity of 12 441 mAh g-1 at a current density of 100 mA g-1. When they were cycled at a limited capacity of 800 mAh g-1 at current densities of 200 or 400 mA g-1, these cathodes showed stable charge voltages of ˜3.65 or 3.90 V, corresponding to energy efficiencies of ˜71.2 or 65.1%, respectively. These results are considerably superior to those of the cathodes based on bare annealed CNTs, which prove that the Fe-N/C catalysts developed here are promising for use in non-aqueous lithium-O2 battery cathodes.

Ionic Liquids in Selective Oxidation: Catalysts and Solvents.

PubMed

Dai, Chengna; Zhang, Jie; Huang, Chongpin; Lei, Zhigang

2017-05-24

Selective oxidation has an important role in environmental and green chemistry (e.g., oxidative desulfurization of fuels and oxidative removal of mercury) as well as chemicals and intermediates chemistry to obtain high-value-added special products (e.g., organic sulfoxides and sulfones, aldehydes, ketones, carboxylic acids, epoxides, esters, and lactones). Due to their unique physical properties such as the nonvolatility, thermal stability, nonexplosion, high polarity, and temperature-dependent miscibility with water, ionic liquids (ILs) have attracted considerable attention as reaction solvents and media for selective oxidations and are considered as green alternatives to volatile organic solvents. Moreover, for easy separation and recyclable utilization, IL catalysts have attracted unprecedented attention as "biphasic catalyst" or "immobilized catalyst" by immobilizing metal- or nonmetal-containing ILs onto mineral or polymer supports to combine the unique properties of ILs (chemical and thermal stability, capacity for extraction of polar substrates and reaction products) with the extended surface of the supports. This review highlights the most recent outcomes on ILs in several important typical oxidation reactions. The contents are arranged in the series of oxidation of sulfides, oxidation of alcohols, epoxidation of alkenes, Baeyer-Villiger oxidation reaction, oxidation of alkanes, and oxidation of other compounds step by step involving ILs as solvents, catalysts, reagents, or their combinations.

Reforming and oxidative dehydrogenation of ethane with CO 2 as a soft oxidant over bimetallic catalysts

DOE PAGES

Myint, MyatNoeZin; Yan, Binhang; Wan, Jie; ...

2016-02-26

An efficient mitigation of abundantly available CO 2 is critical for sustainable environmental impact as well as for novel industrial applications. Using ethane, CO 2 can be catalytically converted into a useful feedstock (synthesis gas) and a value-added monomer (ethylene) via the dry reforming pathway through the C–C bond scission and the oxidative dehydrogenation pathway through the C–H bond scission, respectively. Results from the current flow-reactor study show that the precious metal bimetallic CoPt/CeO 2 catalyst undergoes the reforming reaction to produce syngas with enhanced activity and stability compared to the parent monometallic catalysts. In this paper, in order tomore » replace Pt, the activities of non-precious CoMo/CeO 2 and NiMo/CeO 2 are investigated and the results indicate that NiMo/CeO 2 is nearly as active as CoPt/CeO 2 for the reforming pathway. Furthermore, FeNi/CeO 2 is identified as a promising catalyst for the oxidative dehydrogenation to produce ethylene. Finally, density functional theory (DFT) calculations are performed to further understand the different pathways of the CoPt/CeO 2 and FeNi/CeO 2 catalysts.« less

Reforming and oxidative dehydrogenation of ethane with CO 2 as a soft oxidant over bimetallic catalysts

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

Myint, MyatNoeZin; Yan, Binhang; Wan, Jie

An efficient mitigation of abundantly available CO 2 is critical for sustainable environmental impact as well as for novel industrial applications. Using ethane, CO 2 can be catalytically converted into a useful feedstock (synthesis gas) and a value-added monomer (ethylene) via the dry reforming pathway through the C–C bond scission and the oxidative dehydrogenation pathway through the C–H bond scission, respectively. Results from the current flow-reactor study show that the precious metal bimetallic CoPt/CeO 2 catalyst undergoes the reforming reaction to produce syngas with enhanced activity and stability compared to the parent monometallic catalysts. In this paper, in order tomore » replace Pt, the activities of non-precious CoMo/CeO 2 and NiMo/CeO 2 are investigated and the results indicate that NiMo/CeO 2 is nearly as active as CoPt/CeO 2 for the reforming pathway. Furthermore, FeNi/CeO 2 is identified as a promising catalyst for the oxidative dehydrogenation to produce ethylene. Finally, density functional theory (DFT) calculations are performed to further understand the different pathways of the CoPt/CeO 2 and FeNi/CeO 2 catalysts.« less

The pH-dependent release of platinum group elements (PGEs) from gasoline and diesel fuel catalysts: Implication for weathering in soils.

PubMed

Suchá, Veronika; Mihaljevič, Martin; Ettler, Vojtěch; Strnad, Ladislav

2016-04-15

Powdered samples of new and old gasoline catalysts (Pt, Pd, Rh) and new and old diesel (Pt) catalysts were subjected to a pH-static leaching procedure (pH 2-9) coupled with thermodynamic modeling using PHREEQC-3 to verify the release and mobility of PGEs (platinum group elements). PGEs were released under acidic conditions, mostly exhibiting L-shaped leaching patterns: diesel old: 5.47, 0.005, 0.02; diesel new: 68.5, 0.23, 0.11; gasoline old: 0.1, 11.8, 4.79; gasoline new 2.6, 25.2, 35.9 in mg kg(-1) for Pt, Pd and Rh, respectively. Only the new diesel catalyst had a strikingly different leaching pattern with elevated concentrations at pH 4, probably influenced by the dissolution of the catalyst carrier and washcoat. The pH-static experiment coupled with thermodynamic modeling was found to be an effective instrument for understanding the leaching behavior of PGEs under various environmental conditions, and indicated that charged Pt and Rh species may be adsorbed on the negatively charged surface of kaolinite or Mn oxides in the soil system, whereas uncharged Pd and Rh species may remain mobile in soil solutions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Crab-shell induced synthesis of ordered macroporous carbon nanofiber arrays coupled with MnCo2O4 nanoparticles as bifunctional oxygen catalysts for rechargeable Zn-air batteries.

PubMed

Bin, Duan; Guo, Ziyang; Tamirat, Andebet Gedamu; Ma, Yuanyuan; Wang, Yonggang; Xia, Yongyao

2017-08-10

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out using noble metals (such as Pt) and metal oxides (such as RuO 2 and IrO 2 ) as catalysts, respectively. Nevertheless, several key issues such as high cost, poor stability, and detrimental environmental effects limit the catalytic activity of these noble metal- and metal oxide-based catalysts. Herein, we have designed and synthesized macroporous carbon nanofiber arrays by using a natural crab shell template. Subsequently, spinel MnCo 2 O 4 nanoparticles were embedded into the nitrogen-doped macroporous carbon nanofiber arrays (NMCNAs) by a hydrothermal method. Accompanied by the good conductivity, large surface area and doping of nitrogen, the as-prepared MnCo 2 O 4 /NMCNA exhibited remarkable catalytic performance and outstanding stability for both ORR and OER in alkaline media. The macroporous superstructures play vital role in reducing the ion transport resistance and facilitating the diffusion of gaseous products (O 2 ). Finally, rechargeable Zn-air batteries using the MnCo 2 O 4 /NMCNA catalyst displayed appreciably lower overpotentials, higher power density and better stability than commercial Pt/C, thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal-air batteries.

The concept, reality and utility of single-site heterogeneous catalysts (SSHCs).

PubMed

Thomas, John Meurig

2014-05-07

Very substantial advances have recently been made in the design and construction of solid catalysts and in elucidating both their mode of operation and the factors that determine their selectivity and longevity. This Perspective explains how and why such progress has been made. One important factor, the deployment of single-site heterogeneous and enzymatic catalysts, used either alone or in conjunction with other strategies, including metabolic engineering, enables a multitude of new products (for example, environmentally clean jet fuel) to be readily manufactured. In a practical sense SSHCs enable the advantages of homogeneous and to a lesser degree enzymatic catalysts to be united with those of heterogeneous ones. With the aid of the vastly increasing families of nanoporous solids, desired catalytically active sites may be engineered in atomic detail on their inner, accessible surfaces, thereby opening up new possibilities in synthetic organic chemistry - as in the smooth formation of C-C and C[double bond, length as m-dash]N bonds in a number of intermolecular reactions - as well as in photocatalysts and in fluidized catalytic cracking of hydrocarbons.

Methods for recovering precious metals from industrial waste

NASA Astrophysics Data System (ADS)

Canda, L.; Heput, T.; Ardelean, E.

2016-02-01

The accelerated rate of industrialization increases the demand for precious metals, while high quality natural resources are diminished quantitatively, with significant operating costs. Precious metals recovery can be successfully made from waste, considered to be secondary sources of raw material. In recent years, concerns and interest of researchers for more increasing efficient methods to recover these metals, taking into account the more severe environmental protection legislation. Precious metals are used in a wide range of applications, both in electronic and communications equipment, spacecraft and jet aircraft engines and for mobile phones or catalytic converters. The most commonly recovered precious metals are: gold from jewellery and electronics, silver from X- ray films and photographic emulsions, industrial applications (catalysts, batteries, glass/mirrors), jewellery; platinum group metals from catalytic converters, catalysts for the refining of crude oil, industrial catalysts, nitric acid manufacturing plant, the carbon-based catalyst, e-waste. An important aspect is the economic viability of recycling processes related to complex waste flows. Hydrometallurgical and pyrometallurgical routes are the most important ways of processing electrical and electronic equipment waste. The necessity of recovering precious metals has opened new opportunities for future research.

Reflections on the value of electron microscopy in the study of heterogeneous catalysts

PubMed Central

2017-01-01

Electron microscopy (EM) is arguably the single most powerful method of characterizing heterogeneous catalysts. Irrespective of whether they are bulk and multiphasic, or monophasic and monocrystalline, or nanocluster and even single-atom and on a support, their structures in atomic detail can be visualized in two or three dimensions, thanks to high-resolution instruments, with sub-Ångstrom spatial resolutions. Their topography, tomography, phase-purity, composition, as well as the bonding, and valence-states of their constituent atoms and ions and, in favourable circumstances, the short-range and long-range atomic order and dynamics of the catalytically active sites, can all be retrieved by the panoply of variants of modern EM. The latter embrace electron crystallography, rotation and precession electron diffraction, X-ray emission and high-resolution electron energy-loss spectra (EELS). Aberration-corrected (AC) transmission (TEM) and scanning transmission electron microscopy (STEM) have led to a revolution in structure determination. Environmental EM is already playing an increasing role in catalyst characterization, and new advances, involving special cells for the study of solid catalysts in contact with liquid reactants, have recently been deployed. PMID:28265196

Insights into the effect of the catalytic functions on selective production of ethylene glycol from lignocellulosic biomass over carbon supported ruthenium and tungsten catalysts.

PubMed

Ribeiro, Lucília Sousa; Órfão, José J Melo; Pereira, Manuel Fernando Ribeiro

2018-05-09

The one-pot conversion of cellulose to ethylene glycol (EG) was investigated using a combination of a ruthenium catalyst supported on carbon nanotubes modified with nitric acid (Ru/CNT 1 ) and a tungsten catalyst supported on commercial non-treated carbon nanotubes (W/CNT 0 ). This physical mixture allowed to obtain an EG yield of 41% in just 5 h at 205 °C and 50 bar of H 2 , which overcame the result obtained using a Ru-W bimetallic catalyst supported on commercial carbon nanotubes (35%) under the same conditions. Tissue paper, a potential waste cellulosic material, and eucalyptus were also tested under the same conditions and EG yields of 34 and 36%, respectively, were attained over the aforementioned catalytic physical mixture. To the best of our knowledge, this work presents for the first time the catalytic conversion of lignocellulosic materials, namely tissue paper and eucalyptus, directly into EG by an environmentally friendly process. Copyright © 2018 Elsevier Ltd. All rights reserved.

Decolorization of Methylene Blue by Persulfate Activated with FeO Magnetic Particles.

PubMed

Hung, Chang-Mao; Chen, Chiu-Wen; Liu, Yi-Yuan; Dong, Cheng-Di

2016-08-01

In this study, the degradation of methylene blue (MB) was conducted to evaluate the feasibility of using persulfate oxidation activated with iron oxide (FeO) magnetic particles. The results demonstrated that the decolorization rate of MB increased with increasing FeO concentration, exhibiting maximum efficiency at pH0 3.0. The kinetics of MB was studied in the binary FeO catalyst and persulfate oxidation system. The surface properties of FeO before and after reaction was analyzed using cyclic voltammogram (CV), three-dimensional excitation-emission fluorescence matrix (EEFM) spectroscopy, zeta potential, particle size distribution measurements, X-ray diffraction (XRD) and environmental scanning electron microscopy-energy dispersive X-ray spectrometry (ESEM-EDS). The CV data indicated that a reversible redox reaction holds the key to explaining the significant activity of the catalyst. EEFM was used to evaluate the catalyst yield of FeO by fluorescence intensity plots with excitation/emission at 220/300 nm and 260/300 nm. The XRD and ESEM-EDS results confirmed the presence of FeO in the catalyst.

Green, Enzymatic Syntheses of Divanillin and Diapocynin for the Organic, Biochemistry, or Advanced General Chemistry Laboratory

ERIC Educational Resources Information Center

Nishimura, Rachel T.; Giammanco, Chiara H.; Vosburg, David A.

2010-01-01

Environmentally benign chemistry is an increasingly important topic both in the classroom and the laboratory. In this experiment, students synthesize divanillin from vanillin or diapocynin from apocynin, using horseradish peroxidase and hydrogen peroxide in water. The dimerized products form rapidly at ambient temperature and are isolated by…

Impacts of crop sequence and tillage management on soil carbon stocks in south-central North Dakota, USA

USDA-ARS?s Scientific Manuscript database

Increased emphasis has been placed on developing agroecosystems that are robust, highly productive, economically competitive, and environmentally benign. After 18 years of a study to evaluate effects of crop sequence and tillage, we measured soil properties at various depths to 3 feet (91.4 cm) and ...

Landscape scale estimation of denitrification rate and nitrous oxide to dinitrogen ratio at Georgia and Pennsylvania sites

USDA-ARS?s Scientific Manuscript database

Denitrification results in a significant loss of plant-available nitrogen from agricultural systems and contributes to climate change, due to the emissions of both the potent greenhouse gas nitrous oxide and environmentally benign dinitrogen. However total quantities of the gases emitted and the ra...

Functional genomics analysis of horseweed (Conyza canadensis) with special reference to the evolution of non-target-site glyphosate resistance

USDA-ARS?s Scientific Manuscript database

The evolution of glyphosate resistance in weedy species places an environmentally benign herbicide in peril. The first report of a dicot plant with evolved glyphosate resistance was horseweed, which occurred in 2001. Since then, several species have evolved glyphosate resistance and genomic informat...

Green chemistry for chemical synthesis

PubMed Central

Li, Chao-Jun; Trost, Barry M.

2008-01-01

Green chemistry for chemical synthesis addresses our future challenges in working with chemical processes and products by inventing novel reactions that can maximize the desired products and minimize by-products, designing new synthetic schemes and apparati that can simplify operations in chemical productions, and seeking greener solvents that are inherently environmentally and ecologically benign. PMID:18768813

Stickie removal using neutral enzymatic repulping pressure screening

Treesearch

Marguerite Sykes; John Klungness; Roland Gleisner; Said Abubakr

1998-01-01

Removal of stickie contaminants is currently a major focus of paper recycling research. Medium consistency alkaline repulping followed by pressure screening has proven to be effective for stickie removal. There is, however, an alternate method that is equally effective and more environmentally benign. This study compares the effectiveness of this alternative method,...

Micro-managing arthropod invasions: eradication and control of invasive arthropods with microbes

Treesearch

Ann E. Hajek; Patrick C. Tobin

2010-01-01

Non-indigenous arthropods are increasingly being introduced into new areas worldwide and occasionally they cause considerable ecological and economic harm. Many invasive arthropods particularly pose problems to areas of human habitation and native ecosystems. In these cases, the use of environmentally benign materials, such as host-specific entomopathogens, can be more...

Chemoselective formation of unsymmetrically substituted ethers from catalytic reductive coupling of aldehydes and ketones with alcohols in aqueous solution.

PubMed

Kalutharage, Nishantha; Yi, Chae S

2015-04-03

A well-defined cationic Ru-H complex catalyzes reductive etherification of aldehydes and ketones with alcohols. The catalytic method employs environmentally benign water as the solvent and cheaply available molecular hydrogen as the reducing agent to afford unsymmetrical ethers in a highly chemoselective manner.

Environmentally benign process for the preparation of antimicrobial α-methylene-β-hydroxy-γ-butyrolactone (tulipalin B) from tulip biomass.

PubMed

Nomura, Taiji; Hayashi, Emiko; Kawakami, Shohei; Ogita, Shinjiro; Kato, Yasuo

2015-01-01

Tulipalin B (α-methylene-β-hydroxy-γ-butyrolactone, PaB) is an antimicrobial natural product occurring in tulip (Tulipa gesneriana). PaB is directly formed from the precursor glucose ester 6-tuliposide B (PosB) by endogenous Pos-converting enzyme (TCE). Despite the potential usefulness of antibacterial PaB in various industrial applications, lack of facile synthetic schemes hampers its practical use. Herein, we describe an environmentally benign and facile process for the preparation of PaB using tulip biomass materials based on one-step enzyme reaction catalyzed by TCE without the use of petroleum-derived solvents. By screening 115 tulip cultivars, we found three elite cultivars, which accumulated PosB almost exclusively in flower tissues. The flower extracts with aqueous ethanol were partially purified with activated charcoal and subjected to the enzyme reaction with reusable immobilized TCE prepared from bulb crude extracts. The reaction was completed in a few hours at room temperature, and PaB was purified with activated charcoal and ethanol in a batch-wise manner.

High quality Y-type hexaferrite thick films for microwave applications by an economical and environmentally benign crystal growth technique

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

Hu, Bolin; Chen, Yajie, E-mail: y.chen@neu.edu; Gillette, Scott

2014-02-17

Thick barium hexaferrite Ba{sub 2}Zn{sub 2}Fe{sub 12}O{sub 22} (i.e., Zn{sub 2}Y) films having thicknesses of ∼100 μm were epitaxially grown on MgO (111) substrates using an environmentally benign ferrite-salt mixture by vaporizing the salt. X-ray diffraction pole figure analyses showed (00l) crystallographic alignment with little in plane dispersion confirming epitaxial growth. Saturation magnetization, 4πM{sub s}, was measured for as-grown films to be 2.51 ± 0.1 kG with an out of plane magnetic anisotropy field H{sub A} of 8.9 ± 0.1 kOe. Ferromagnetic resonance linewidth, as the peak-to-peak power absorption derivative at 9.6 GHz, was measured to be 62 Oe. These properties demonstrate a rapid, convenient, cost-effective, and nontoxic methodmore » of growing high quality thick crystalline ferrite films which could be used widely for microwave device applications.« less

NON-TRADITIONAL APPROACHES FOR PHARMACEUTICALLY RELEVANT SYNTHETIC TRANSFORMATIONS

EPA Science Inventory

A rapid and environmentally friendlier approach for organic synthesis, and transformations is described which involves microwave (MW) exposure of neat reactants (undiluted) often in presence of inorganic oxides as recyclable catalysts such as alumina, silica, clay, or 'doped' sur...

Environmentally Sound Processing Technology: JANNAF Safety and Environmental Protection Subcommittee and Propellant Development and Characterization Subcommittee Joint Workshop

NASA Technical Reports Server (NTRS)

Pickett, Lorri A. (Editor)

1995-01-01

Topics covered include: Risk assessment of hazardous materials, Automated systems for pollution prevention and hazardous materials elimination, Study design for the toxicity evaluation of ammonium perchlorate, Plasma sprayed bondable stainless surface coatings, Development of CFC-free cleaning processes, New fluorinated solvent alternatives to ozone depleting solvents, Cleaning with highly fluorinated liquids, Biotreatment of propyleneglycol nitrate by anoxic denitrification, Treatment of hazardous waste with white rot fungus, Hydrothermal oxidation as an environmentally benign treatment technology, Treatment of solid propellant manufacturing wastes by base hydrolysis, Design considerations for cleaning using supercritical fluid technology, and Centrifugal shear carbon dioxide cleaning.

The influence of catalysts on biofuel life cycle analysis (LCA)

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

Benavides, Pahola Thathiana; Cronauer, Donald C.; Adom, Felix K.

Catalysts play an important role in biofuel production but are rarely included in biofuel life cycle analysis (LCA). In this work, we estimate the cradle-to-gate energy consumption and greenhouse gas (GHG) emissions of Pt/γ-Al 2O 3, CoMo/γ-Al 2O 3, and ZSM-5, catalysts that could be used in processes to convert biomass to biofuels. We also consider the potential impacts of catalyst recovery and recycling. Integrating the energy and environmental impacts of CoMo/γ-Al 2O 3 and ZSM-5 into an LCA of renewable gasoline produced via in-situ and ex-situ fast pyrolysis of a blended woody feedstock revealed that the ZSM-5, with cradle-to-gatemore » GHG emissions of 7.7 kg CO 2e/kg, could influence net life-cycle GHG emissions of the renewable gasoline (1.7 gCO 2e/MJ for the in-situ process, 1.2 gCO 2e/MJ for the ex-situ process) by up to 14% depending on the loading rate. CoMo/γ-Al 2O 3 had a greater GHG intensity (9.6 kg CO 2e/kg) than ZSM-5, however, it contributed approximately only 1% to the life-cycle GHG emissions of the renewable gasoline because of the small amount of this catalyst needed per kg of biofuel produced. As a result, given that catalysts can contribute significantly to biofuel life-cycle GHG emissions depending on the GHG intensity of their production and their consumption rates, biofuel LCAs should consider the potential influence of catalysts on LCA results.« less

Water-medium and solvent-free organic reactions over a bifunctional catalyst with Au nanoparticles covalently bonded to HS/SO3H functionalized periodic mesoporous organosilica.

PubMed

Zhu, Feng-Xia; Wang, Wei; Li, He-Xing

2011-08-03

An operationally simple approach for the preparation of a new class of bifunctional Au nanoparticle-acid catalysts has been developed. In situ reduction of Au(3+) with HS-functionalized periodic mesoporous organosilicas (PMOs) creates robust, fine Au nanoparticles and concomitantly produces a sulfonic acid moiety strongly bonded to PMOs. Characterizations of the nanostructures reveal that Au nanoparticles are formed with uniformed, narrow size distribution around 1-2 nm, which is very critical for essential catalytic activities. Moreover, the Au nanoparticles are mainly attached onto the pore surface rather than onto the outer surface with ordered mesoporous channels, allowing for maximal exposure to reaction substrates while minimizing Au nanoparticle leaching. Their higher S(BET), V(P), and D(P) than either the Au-HS-PMO(Et) or the Au/SO(3)H-PMO(Et) render the catalyst with comparably even higher catalytic efficiency than its homogeneous counterparts. Furthermore, the unique amphiphilic compartment of the Au-HS/SO(3)H-PMO(Et) nanostructures enables organic reactions to proceed efficiently in a pure aqueous solution without using any organic solvents or even without water. As demonstrated experimentally, remarkably, the unique bifunctional Au-HS/SO(3)H-PMO(Et) catalyst displays higher efficiencies in promoting water-medium alkyne hydration, intramolecular hydroamination, styrene oxidation, and three-component coupling reactions and even the solvent-free alkyne hydration process than its homogeneous catalysts. The robust catalyst can be easily recycled and used repetitively at least 10 times without loss of catalytic efficiency. These features render the catalyst particularly attractive in the practice of organic synthesis in an environmentally friendly manner.

Facile one-pot synthesis of cellulose nanocrystal-supported hollow CuFe2O4 nanoparticles as efficient catalyst for 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Zhang, Sufeng; Zhao, Dongyan; Hou, Chen; Liang, Chen; Li, Hao

2018-06-01

A facile and efficient one-pot method for the synthesis of well-dispersed hollow CuFe2O4 nanoparticles (H-CuFe2O4 NPs) in the presence of cellulose nanocrystals (CNC) as the support was described. Based on the one-pot solvothermal condition control, magnetic H-CuFe2O4 NPs were in-situ grown on the CNC surface uniformly. TEM images indicated good dispersity of H-CuFe2O4 NPs with uniform size of 300 nm. The catalytic activity of H-CuFe2O4/CNC was tested in the catalytic reduction of 4-nitrophenol (4-NP) in aqueous solution. Compared with most CNC-based ferrite catalysts, H-CuFe2O4/CNC catalyst exhibited an excellent catalytic activity toward the reduction of 4-NP. The catalytic performance of H-CuFe2O4/CNC catalyst was remarkably enhanced with the rate constant of 3.24 s-1 g-1, which was higher than H-CuFe2O4 NPs (0.50 s-1 g-1). The high catalytic activity was attributed to the introduction of CNC and the special hollow mesostructure of H-CuFe2O4 NPs. In addition, the H-CuFe2O4/CNC catalyst promised good conversion efficiency without significant decrease even after 10 cycles, confirming relatively high stability. Because of its environmental sustainability and magnetic separability, H-CuFe2O4/CNC catalyst was shown to indicate that the ferrite nanoparticles supported on CNC were acted as a promising catalyst and exhibited potential applications in numerous ferrite based catalytic reactions.

The influence of catalysts on biofuel life cycle analysis (LCA)

DOE PAGES

Benavides, Pahola Thathiana; Cronauer, Donald C.; Adom, Felix K.; ...

2017-01-21

Catalysts play an important role in biofuel production but are rarely included in biofuel life cycle analysis (LCA). In this work, we estimate the cradle-to-gate energy consumption and greenhouse gas (GHG) emissions of Pt/γ-Al 2O 3, CoMo/γ-Al 2O 3, and ZSM-5, catalysts that could be used in processes to convert biomass to biofuels. We also consider the potential impacts of catalyst recovery and recycling. Integrating the energy and environmental impacts of CoMo/γ-Al 2O 3 and ZSM-5 into an LCA of renewable gasoline produced via in-situ and ex-situ fast pyrolysis of a blended woody feedstock revealed that the ZSM-5, with cradle-to-gatemore » GHG emissions of 7.7 kg CO 2e/kg, could influence net life-cycle GHG emissions of the renewable gasoline (1.7 gCO 2e/MJ for the in-situ process, 1.2 gCO 2e/MJ for the ex-situ process) by up to 14% depending on the loading rate. CoMo/γ-Al 2O 3 had a greater GHG intensity (9.6 kg CO 2e/kg) than ZSM-5, however, it contributed approximately only 1% to the life-cycle GHG emissions of the renewable gasoline because of the small amount of this catalyst needed per kg of biofuel produced. As a result, given that catalysts can contribute significantly to biofuel life-cycle GHG emissions depending on the GHG intensity of their production and their consumption rates, biofuel LCAs should consider the potential influence of catalysts on LCA results.« less

Polymer nanocomposite membranes with hierarchically structured catalysts for high throughput dehalogenation

NASA Astrophysics Data System (ADS)

Crock, Christopher A.

Halogenated organics are categorized as primary pollutants by the Environmental Protection Agency. Trichloroethylene (TCE), which had broad industrial use in the past, shows persistence in the environment because of its chemical stability. The large scale use and poor control of TCE resulted in its prolonged release into the environment before the carcinogenic risk associated with TCE was fully understood. TCE pollution stemmed from industrial effluents and improper disposal of solvent waste. Membrane reactors are promising technology for treating TCE polluted groundwater because of the high throughput, relatively low cost of membrane fabrication and facile retrofitting of existing membrane based water treatment facilities with catalytic membrane reactors. Compared to catalytic fluidized or fixed bed reactors, catalytic membrane reactors feature minimal diffusional limitation. Additionally, embedding catalyst within the membrane avoids the need for catalyst recovery and can prevent aggregation of catalytic nanoparticles. In this work, Pd/xGnP, Pd-Au/xGnP, and commercial Pd/Al2O3 nanoparticles were employed in batch and flow-through membrane reactors to catalyze the dehalogenation of TCE in the presence of dissolved H2. Bimetallic Pd-Au/xGnP catalysts were shown to be more active than monometallic Pd/xGnP or commercial Pd/Al 2O3 catalysts. In addition to synthesizing nanocomposite membranes for high-throughput TCE dehalogenation, the membrane based dehalogenation process was designed to minimize the detrimental impact of common catalyst poisons (S2-, HS-, and H2S -) by concurrent oxidation of sulfide species to gypsum in the presence of Ca2+ and removal of gypsum through membrane filtration. The engineered membrane dehalogenation process demonstrated that bimetallic Pd-Au/xGnP catalysts resisted deactivation by residual sulfide species after oxidation, and showed complete removal of gypsum during membrane filtration.

Propagation of a plasma streamer in catalyst pores

NASA Astrophysics Data System (ADS)

Zhang, Quan-Zhi; Bogaerts, Annemie

2018-03-01

Although plasma catalysis is gaining increasing interest for various environmental applications, the underlying mechanisms are still far from understood. For instance, it is not yet clear whether and how plasma streamers can propagate in catalyst pores, and what is the minimum pore size to make this happen. As this is crucial information to ensure good plasma-catalyst interaction, we study here the mechanism of plasma streamer propagation in a catalyst pore, by means of a two-dimensional particle-in-cell/Monte Carlo collision model, for various pore diameters in the nm-range to μm-range. The so-called Debye length is an important criterion for plasma penetration into catalyst pores, i.e. a plasma streamer can penetrate into pores when their diameter is larger than the Debye length. The Debye length is typically in the order of a few 100 nm up to 1 μm at the conditions under study, depending on electron density and temperature in the plasma streamer. For pores in the range of ∼50 nm, plasma can thus only penetrate to some extent and at very short times, i.e. at the beginning of a micro-discharge, before the actual plasma streamer reaches the catalyst surface and a sheath is formed in front of the surface. We can make plasma streamers penetrate into smaller pores (down to ca. 500 nm at the conditions under study) by increasing the applied voltage, which yields a higher plasma density, and thus reduces the Debye length. Our simulations also reveal that the plasma streamers induce surface charging of the catalyst pore sidewalls, causing discharge enhancement inside the pore, depending on pore diameter and depth.

Alkali promoted molybdenum (IV) sulfide based catalysts, development and characterization for alcohol synthesis from carbon monoxide and hydrogen

NASA Astrophysics Data System (ADS)

Molina, Belinda Delilah

For more than a century transition metal sulfides (TMS) have been the anchor of hydro-processing fuels and upgrading bitumen and coal in refineries worldwide. As oil supplies dwindle and environmental laws become more stringent, there is a greater need for cleaner alternative fuels and/or synthetic fuels. The depletion of oil reserves and a rapidly increasing energy demand worldwide, together with the interest to reduce dependence on foreign oil makes alcohol production for fuels and chemicals via the Fischer Tropsch synthesis (FTS) very attractive. The original Fischer-Tropsch (FT) reaction is the heart of all gas-to-liquid technologies; it creates higher alcohols and hydrocarbons from CO/H2 using a metal catalyst. This research focuses on the development of alkali promoted MoS2-based catalysts to investigate an optimal synthesis for their assistance in the production of long chain alcohols (via FTS) for their use as synthetic transportation liquid fuels. Properties of catalytic material are strongly affected by every step of the preparation together with the quality of the raw materials. The choice of a laboratory method for preparing a given catalyst depends on the physical and chemical characteristics desired in the final composition. Characterization methods of K0.3/Cs0.3-MoS2 and K0.3 /Cs0.3-Co0.5MoS2 catalysts have been carried out through Scanning Electron Microscopy (SEM), BET porosity and surface analysis, Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). Various characterization methods have been deployed to correlate FTS products versus crystal and morphological properties of these heterogeneous catalysts. A lab scale gas to liquid system has been developed to evaluate its efficiency in testing FT catalysts for their production of alcohols.

Bulk scale production of carbon nanofibers in an economical way

NASA Astrophysics Data System (ADS)

Rajarao, Ravindra; Bhat, Badekai Ramachandra

2012-12-01

An economical route for the scalable production of carbon nanofibers (CNFs) on a sodium chloride support has been developed. CNFs have been synthesized by chemical vapor deposition (CVD) method by using metal formate as catalyst precursors at 680°C. Products were characterized by SEM, TEM, Raman spectroscopy and XRD method. By thermal analysis, the purity of the as grown products and purified products were determined. This method avoids calcination and reduction process which was employed in commercial catalysts such as metal oxide or nitrate. The problems such as detrimental effect, environmental and even cost have been overcome by using sodium chloride as support. The yield of CNFs up to 7800 wt.% relative to the nickel catalyst has been achieved in the growth time of 15 min. The advantage of this synthesis technique is the simplicity and use of easily available low cost precursors.

Observing Graphene Grow: Catalyst–Graphene Interactions during Scalable Graphene Growth on Polycrystalline Copper

PubMed Central

2013-01-01

Complementary in situ X-ray photoelectron spectroscopy (XPS), X-ray diffractometry, and environmental scanning electron microscopy are used to fingerprint the entire graphene chemical vapor deposition process on technologically important polycrystalline Cu catalysts to address the current lack of understanding of the underlying fundamental growth mechanisms and catalyst interactions. Graphene forms directly on metallic Cu during the high-temperature hydrocarbon exposure, whereby an upshift in the binding energies of the corresponding C1s XPS core level signatures is indicative of coupling between the Cu catalyst and the growing graphene. Minor carbon uptake into Cu can under certain conditions manifest itself as carbon precipitation upon cooling. Postgrowth, ambient air exposure even at room temperature decouples the graphene from Cu by (reversible) oxygen intercalation. The importance of these dynamic interactions is discussed for graphene growth, processing, and device integration. PMID:24041311

NON-TRADITIONAL 'GREENER' ALTERNATIVES TO SYNTHETIC ORGANIC TRANSFORMATIONS USING MICROWAVES

EPA Science Inventory

A rapid and environmentally friendlier approach for organic synthesis and transformations is described which involves microwave (MW) exposure of neat reactants (undiluted) often in presence of inorganic oxides as recyclable catalysts such as alumina, silica, clay, or 'doped' surf...

Toward Rational Design of Cu/SSZ-13 Selective Catalytic Reduction Catalysts: Implications from Atomic-Level Understanding of Hydrothermal Stability

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

Song, James; Wang, Yilin; Walter, Eric D.

The hydrothermal stability of Cu/SSZ-13 SCR catalysts has been extensively studied, yet atomic level understanding of changes to the zeolite support and the Cu active sites during hydrothermal aging are still lacking. In this work, via the utilization of spectroscopic methods including solid-state 27Al and 29Si NMR, EPR, DRIFTS, and XPS, together with imaging and elemental mapping using STEM, detailed kinetic analyses, and theoretical calculations with DFT, various Cu species, including two types of isolated active sites and CuOx clusters, were precisely quantified for samples hydrothermally aged under varying conditions. This quantification convincingly confirms the exceptional hydrothermal stability of isolatedmore » Cu2+-2Z sites, and the gradual conversion of [Cu(OH)]+-Z to CuOx clusters with increasing aging severity. This stability difference is rationalized from the hydrolysis activation barrier difference between the two isolated sites via DFT. Discussions are provided on the nature of the CuOx clusters, and their possible detrimental roles on catalyst stability. Finally, a few rational design principles for Cu/SSZ-13 are derived rigorously from the atomic-level understanding of this catalyst obtained here. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. Computing time was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC). The experimental studies described in this paper were performed in the EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less

Evaluation of a hybrid ion exchange-catalyst treatment technology for nitrate removal from drinking water.

PubMed

Bergquist, Allison M; Choe, Jong Kwon; Strathmann, Timothy J; Werth, Charles J

2016-06-01

Ion exchange (IX) is the most common approach to treating nitrate-contaminated drinking water sources, but the cost of salt to make regeneration brine, as well as the cost and environmental burden of waste brine disposal, are major disadvantages. A hybrid ion exchange-catalyst treatment system, in which waste brine is catalytically treated for reuse, shows promise for reducing costs and environmental burdens of the conventional IX system. An IX model with separate treatment and regeneration cycles was developed, and ion selectivity coefficients for each cycle were separately calibrated by fitting experimental data. Of note, selectivity coefficients for the regeneration cycle required fitting the second treatment cycle after incomplete resin regeneration. The calibrated and validated model was used to simulate many cycles of treatment and regeneration using the hybrid system. Simulated waste brines and a real brine obtained from a California utility were also evaluated for catalytic nitrate treatment in a packed-bed, flow-through column with 0.5 wt%Pd-0.05 wt%In/activated carbon support (PdIn/AC). Consistent nitrate removal and no apparent catalyst deactivation were observed over 23 d (synthetic brine) and 45 d (real waste brine) of continuous-flow treatment. Ion exchange and catalyst results were used to evaluate treatment of 1 billion gallons of nitrate-contaminated source water at a 0.5 MGD water treatment plant. Switching from a conventional IX system with a two bed volume regeneration to a hybrid system with the same regeneration length and sequencing batch catalytic reactor treatment would save 76% in salt cost. The results suggest the hybrid system has the potential to address the disadvantages of a conventional IX treatment systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

PubMed

Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

2015-11-01

Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. Copyright © 2015 Elsevier Inc. All rights reserved.

Part I. improve flame retardant textile. Part II. novel approach layer-by-layer processing for flame retardant textile.

USDA-ARS?s Scientific Manuscript database

In this presentation, new approaches for flame retardant textile by using supercritical carbon dioxide (scCO2) and layer-by-layer processing will be discussed. Due to its environmentally benign character, the scCO2 is considered in green chemistry as a substitute for organic solvents in chemical rea...

Validation of laboratory-scale recycling test method of paper PSA label products

Treesearch

Carl Houtman; Karen Scallon; Richard Oldack

2008-01-01

Starting with test methods and a specification developed by the U.S. Postal Service (USPS) Environmentally Benign Pressure Sensitive Adhesive Postage Stamp Program, a laboratory-scale test method and a specification were developed and validated for pressure-sensitive adhesive labels, By comparing results from this new test method and pilot-scale tests, which have been...

Multi-component biocide protects wood from fungi and insects in UC2 applications

Treesearch

Carol A. Clausen; Vina W. Yang

2007-01-01

Development of synergistic biocides to protect wood in interior applications has been of particular interest since the recent increase of indoor mold infestations. Many products have been developed to address the recent influx of indoor mold infestations. Researchers must emphasize the use of environmentally benign chemicals due to the need for safety of human...

Development of USPS Laboratory and pilot-scale testing protocols

Treesearch

Carl Houtman; Nancy Ross Sutherland; David Bormett; Donald Donermeyer

2000-01-01

The ultimate goal of the US Postal Service (USPS) Environmentally Benign Stamp Program is to develop stamp adhesives that can be removed by unit operations found in recycling mills. The maintenance of final product quality specifications for a recycling mill while loading the feedstock with a significant quantity of adhesive is the criterion for success of this program...

Copper-Catalyzed C(sp2)-S Coupling Reactions for the Synthesis of Aryl Dithiocarbamates with Thiuram Disulfide Reagents.

PubMed

Dong, Zhi-Bing; Liu, Xing; Bolm, Carsten

2017-11-03

An efficient protocol for the copper-catalyzed preparation of aryl dithiocarbamates from aryl iodides and inexpensive, environmentally benign tetraalkylthiuram disulfides was developed. The features of mild reaction conditions, high yields, and broad substrate scope render this new approach synthetically attractive for the preparation of potentially biologically active compounds.

Assessment of biodeterioration for the screening of new wood preservatives : calculation of stiffness loss in rapid decay testing

Treesearch

Simon R. Przewloka; Douglas M. Crawford; Douglas R. Rammer; Donald L. Buckner; Bessie M. Woodward; Gan Li; Darrel D. Nicholas

2008-01-01

Demand for the development of environmentally benign wood preservatives has increased significantly. To reduce the evaluation time of prospective candidates, reliable accelerated decay methodologies are necessary for laboratory screening of potential preservatives. Ongoing research at Mississippi State University has focused upon utilizing custom built equipment to...

A Game Approach to Teach Environmentally Benign Manufacturing in the Supply Chain

ERIC Educational Resources Information Center

Qualters, Donna M.; Isaacs, Jacqueline A.; Cullinane, Thomas P.; Laird, Jay; McDonald, Ann

2008-01-01

Multidisciplinary models of education are needed to prepare students for their role in a global work environment. Combined with this need is the reality of the new Millennial Generation entering the educational system with a different approach to learning. This paper introduces an interactive, educational engineering game designed to appeal to the…

Impacts of crop sequence and minimum and no-till cropping systems on soil carbon stocks in south-central North Dakota, USA

USDA-ARS?s Scientific Manuscript database

Increased emphasis has been placed on developing agroecosystems that are inherently resistant and resilient to external stressors, yet are highly productive, economically competitive, and environmentally benign. As part of a long-term study to evaluate effects of crop sequence and tillage on crop yi...

Innovative approach to solving "stickies" problem and developing environmentally benign pressure sensitive adhesives through partnerships

Treesearch

Said M. Abubakr; Joe Peng

1999-01-01

As a result of a United States Postal Service (USPS) initiative, a work team consisting of the USPS, the Forest Products Laboratory (FPL),Springborn Testing and Research (STR), and industry representatives wasformed. The industry representatives include papermakers, paper recyclers,paper collectors, equipment manufacturers, paper users, and adhesive and chemical...

A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway.

PubMed

Liu, Jinyong; Han, Mengwei; Wu, Dimao; Chen, Xi; Choe, Jong Kwon; Werth, Charles J; Strathmann, Timothy J

2016-06-07

Rapid reduction of aqueous ClO4(-) to Cl(-) by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx(-) intermediates formed during reactions with concentrated ClO4(-) promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4(-) reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2(-) intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4(-) reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx(-) scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx(-) intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4(-) reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4(-). This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications.

Applications of Neutron Scattering in the Chemical Industry: Proton Dynamics of Highly Dispersed Materials, Characterization of Fuel Cell Catalysts, and Catalysts from Large-Scale Chemical Processes

NASA Astrophysics Data System (ADS)

Albers, Peter W.; Parker, Stewart F.

The attractiveness of neutron scattering techniques for the detailed characterization of materials of high degrees of dispersity and structural complexity as encountered in the chemical industry is discussed. Neutron scattering picks up where other analytical methods leave off because of the physico-chemical properties of finely divided products and materials whose absorption behavior toward electromagnetic radiation and electrical conductivity causes serious problems. This is demonstrated by presenting typical applications from large-scale production technology and industrial catalysis. These include the determination of the proton-related surface chemistry of advanced materials that are used as reinforcing fillers in the manufacture of tires, where interrelations between surface chemistry, rheological properties, improved safety, and significant reduction of fuel consumption are the focus of recent developments. Neutron scattering allows surface science studies of the dissociative adsorption of hydrogen on nanodispersed, supported precious metal particles of fuel cell catalysts under in situ loading at realistic gas pressures of about 1 bar. Insight into the occupation of catalytically relevant surface sites provides valuable information about the catalyst in the working state and supplies essential scientific input for tailoring better catalysts by technologists. The impact of deactivation phenomena on industrial catalysts by coke deposition, chemical transformation of carbonaceous deposits, and other processes in catalytic hydrogenation processes that result in significant shortening of the time of useful operation in large-scale plants can often be traced back in detail to surface or bulk properties of catalysts or materials of catalytic relevance. A better understanding of avoidable or unavoidable aspects of catalyst deactivation phenomena under certain in-process conditions and the development of effective means for reducing deactivation leads to more energy-efficient and, therefore, environmentally friendly processes and helps to save valuable resources. Even small or gradual improvements in all these fields are of considerable economic impact.

HOMOGENEOUS CATALYSTS FOR THE PARTIAL-OXYGENATION OF SATURATED HYDROCARBONS WITH HYDROGEN PERIOXIDE

EPA Science Inventory

A Methodology for the Evaluation of Process Sustainability
Michael Gonzalez*, Raymond Smith and Thomas Becker

United States Environmental Protection Agency; Office of Research and Development; Sustainable Technologies Division; 26 West Martin Luther King Drive; Cincinna...

SELECTIVE OXIDATION OF STYRENE TO ACETOPHENONE IN PRESENCE OF IONIC LIQUIDS

EPA Science Inventory

Palladium-catalyzed oxidation of styrene (Wacker reaction) in the presence of 1,3-dialkylimidazolium cation based ionic liquids is described. The effect of temperature, use of co-catalyst, and recyclability aspects for the generation of carbonyl compounds using environmentally de...

Development of a Global Marine Environmental Library

DTIC Science & Technology

2010-06-01

Gulf. Marine Geology , 129, 237- 269. [4] Lerner, S., & Maffei, A. (2001). 4DGeoBrowser: A Web-based data browser and server for accessing and...Digital Library as a Catalyst for Collaboration: Voyages across Disciplinary and Institutional Boundaries with SIO Explorer; Digital Scholarship

An environmental benign process for cobalt and lithium recovery from spent lithium-ion batteries by mechanochemical approach.

PubMed

Wang, Meng-Meng; Zhang, Cong-Cong; Zhang, Fu-Shen

2016-05-01

In the current study, an environmental benign process namely mechanochemical approach was developed for cobalt and lithium recovery from spent lithium-ion batteries (LIBs). The main merit of the process was that neither corrosive acid nor strong oxidant was applied. In the proposed process, lithium cobalt oxide (obtained from spent LIBs) was firstly co-grinded with various additives in a hermetic ball milling system, then Co and Li could be easily recovered by a water leaching procedure. It was found that EDTA was the most suitable co-grinding reagent, and 98% of Co and 99% of Li were respectively recovered under optimum conditions: LiCoO2 to EDTA mass ratio 1:4, milling time 4h, rotary speed 600r/min and ball-to-powder mass ratio 80:1, respectively. Mechanisms study implied that lone pair electrons provided by two nitrogen atoms and four hydroxyl oxygen atoms of EDTA could enter the empty orbit of Co and Li by solid-solid reaction, thus forming stable and water-soluble metal chelates Li-EDTA and Co-EDTA. Moreover, the separation of Co and Li could be achieved through a chemical precipitation approach. This study provides a high efficiency and environmentally friendly process for Co and Li recovery from spent LIBs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Current advances in precious metal core-shell catalyst design.

PubMed

Wang, Xiaohong; He, Beibei; Hu, Zhiyu; Zeng, Zhigang; Han, Sheng

2014-08-01

Precious metal nanoparticles are commonly used as the main active components of various catalysts. Given their high cost, limited quantity, and easy loss of catalytic activity under severe conditions, precious metals should be used in catalysts at low volumes and be protected from damaging environments. Accordingly, reducing the amount of precious metals without compromising their catalytic performance is difficult, particularly under challenging conditions. As multifunctional materials, core-shell nanoparticles are highly important owing to their wide range of applications in chemistry, physics, biology, and environmental areas. Compared with their single-component counterparts and other composites, core-shell nanoparticles offer a new active interface and a potential synergistic effect between the core and shell, making these materials highly attractive in catalytic application. On one hand, when a precious metal is used as the shell material, the catalytic activity can be greatly improved because of the increased surface area and the closed interfacial interaction between the core and the shell. On the other hand, when a precious metal is applied as the core material, the catalytic stability can be remarkably improved because of the protection conferred by the shell material. Therefore, a reasonable design of the core-shell catalyst for target applications must be developed. We summarize the latest advances in the fabrications, properties, and applications of core-shell nanoparticles in this paper. The current research trends of these core-shell catalysts are also highlighted.

Evolution of Active Sites in Pt-Based Nanoalloy Catalysts for the Oxidation of Carbonaceous Species by Combined in Situ Infrared Spectroscopy and Total X-ray Scattering.

PubMed

Petkov, Valeri; Maswadeh, Yazan; Lu, Aolin; Shan, Shiyao; Kareem, Haval; Zhao, Yinguang; Luo, Jin; Zhong, Chuan-Jian; Beyer, Kevin; Chapman, Karena

2018-04-04

We present results from combined in situ infrared spectroscopy and total X-ray scattering studies on the evolution of catalytically active sites in exemplary binary and ternary Pt-based nanoalloys during a sequence of CO oxidation-reactivation-CO oxidation reactions. We find that when within a particular compositional range, the fresh nanoalloys may exhibit high catalytic activity for low-temperature CO oxidation. Using surface-specific atomic pair distribution functions (PDFs) extracted from the in situ total X-ray scattering data, we find that, regardless of their chemical composition and initial catalytic activity, the fresh nanoalloys suffer a significant surface structural disorder during CO oxidation. Upon reactivation in oxygen atmosphere, the surface of used nanoalloy catalysts both partially oxidizes and orders. Remarkably, it largely retains its structural state when the nanoalloys are reused as CO oxidation catalysts. The seemingly inverse structural changes of studied nanoalloy catalysts occurring under CO oxidation and reactivation conditions affect the active sites on their surface significantly. In particular, through different mechanisms, both appear to reduce the CO binding strength to the nanoalloy's surface and thus increase the catalytic stability of the nanoalloys. The findings provide clues for further optimization of nanoalloy catalysts for the oxidation of carbonaceous species through optimizing their composition, activation, and reactivation. Besides, the findings demonstrate the usefulness of combined in situ infrared spectroscopy and total X-ray scattering coupled to surface-specific atomic PDF analysis to the ongoing effort to produce advanced catalysts for environmentally and technologically important applications.

Cat cracking technology with reduced discharge of harmful substances to the atmosphere

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

Elshin, A.I.; Aliev, R.R.; Solyar, B.Z.

1995-11-01

The operation of cat crackers creates a number of ecological problems involving pollution of the atmosphere. In the regeneration of coked catalyst, up to 10 tonnes/day of sulfur oxides are discharged to the atmosphere, along with catalyst dust in amounts up to 2 tonnes/day and carbon monoxide up to 120 tonnes/day. With increasingly severe requirements for environmental protection, the problem of reducing harmful discharges to the atmosphere has become more acute, necessitating either preliminary hydrotreating of the feed or scrubber cleanup of the stack gas to remove sulfur oxides. The high cost of these processes has provided the impetus formore » proposing various types of bifunctional cracking catalysts and effective catalyst additives to bind sulfur oxides directly in the regenerator. Basic oxides (of aluminum, magnesium, calcium, etc.) react with sulfur oxides to form stable sulfates that are then reduced to hydrogen sulfide in the reactor, while re-forming the basic oxide. Binding sulfur oxides in the regenerator is favored by the presence of an oxidizing agent or by the introduction of a promoter for afterburning carbon monoxide to dioxide. Compositions consisting mainly of aluminum oxide ({>=}90% by weight) have been patented as catalyst additives for binding sulfur oxides; other compositions that have been patented consist of Group II metal oxides and other oxides that have oxidizing properties. The additives are introduced into the catalyst charge in amounts of 5-10% by weight. On the basis of research, an aluminium oxide additive, PS-17, has been developed for binding sulfur oxides in the course of cracking.« less

Innovative PCDD/F-containing gas stream generating system applied in catalytic decomposition of gaseous dioxins over V2O5-WO3/TiO2-based catalysts.

PubMed

Yang, Chia Cheng; Chang, Shu Hao; Hong, Bao Zhen; Chi, Kai Hsien; Chang, Moo Been

2008-10-01

Development of effective PCDD/F (polychlorinated dibenzo-p-dioxin and dibenzofuran) control technologies is essential for environmental engineers and researchers. In this study, a PCDD/F-containing gas stream generating system was developed to investigate the efficiency and effectiveness of innovative PCDD/F control technologies. The system designed and constructed can stably generate the gas stream with the PCDD/F concentration ranging from 1.0 to 100ng TEQ Nm(-3) while reproducibility test indicates that the PCDD/F recovery efficiencies are between 93% and 112%. This new PCDD/F-containing gas stream generating device is first applied in the investigation of the catalytic PCDD/F control technology. The catalytic decomposition of PCDD/Fs was evaluated with two types of commercial V(2)O(5)-WO(3)/TiO(2)-based catalysts (catalyst A and catalyst B) at controlled temperature, water vapor content, and space velocity. 84% and 91% PCDD/F destruction efficiencies are achieved with catalysts A and B, respectively, at 280 degrees C with the space velocity of 5000h(-1). The results also indicate that the presence of water vapor inhibits PCDD/F decomposition due to its competition with PCDD/F molecules for adsorption on the active vanadia sites for both catalysts. In addition, this study combined integral reaction and Mars-Van Krevelen model to calculate the activation energies of OCDD and OCDF decomposition. The activation energies of OCDD and OCDF decomposition via catalysis are calculated as 24.8kJmol(-1) and 25.2kJmol(-1), respectively.

Metallic bionanocatalysts: potential applications as green catalysts and energy materials.

PubMed

Macaskie, Lynne E; Mikheenko, Iryna P; Omajai, Jacob B; Stephen, Alan J; Wood, Joseph

2017-09-01

Microbially generated or supported nanocatalysts have potential applications in green chemistry and environmental application. However, precious (and base) metals biorefined from wastes may be useful for making cheap, low-grade catalysts for clean energy production. The concept of bionanomaterials for energy applications is reviewed with respect to potential fuel cell applications, bio-catalytic upgrading of oils and manufacturing 'drop-in fuel' precursors. Cheap, effective biomaterials would facilitate progress towards dual development goals of sustainable consumption and production patterns and help to ensure access to affordable, reliable, sustainable and modern energy. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

A Cu/Pt Near-Surface Alloy for Water-Gas Shift Catalysis.

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

Knudsen, Jan; Nilekar, Anand U.; Vang, Ronnie T.

2007-05-01

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, 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. The primary route to hydrogen production from fossil fuels involves the water-gas shift (WGS) reaction, and an improvement in the efficiency of WGS catalysts could therefore lead to a major leap forward in the realization of hydrogen economy. On the basis of a combination of high-resolution scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations, we suggestmore » the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA). Temperature-programmed desorption and DFT reveal that this Cu/Pt NSA binds CO significantly more weakly than does Pt alone, thereby implying a considerable reduction in the potential for CO poisoning of the Cu/Pt NSA surface as compared to that of pure Pt. In addition, DFT calculations show that this Cu/Pt NSA is able to activate H2O easily, which is the rate-determining step for the WGS on several metal surfaces, and, at the same time, to bind the products of that reaction and formate intermediates rather weakly, thus avoiding possible poisoning of the catalyst surface. The Cu/Pt NSA is thus a promising candidate for an improved WGS catalyst.« less

Minimizing the formation of coke and methane on Co nanoparticles in steam reforming of biomass-derived oxygenates

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

Sun, Junming; Mei, Donghai; Karim, Ayman M.

2013-06-01

Fundamental understanding and control of chemical transformations are essential to the development of technically feasible and economically viable catalytic processes for efficient conversion of biomass to fuels and chemicals. Using an integrated experimental and theoretical approach, we report high hydrogen selectivity and catalyst durability of acetone steam reforming (ASR) on inert carbon supported Co nanoparticles. The observed catalytic performance is further elucidated on the basis of comprehensive first-principles calculations. Instead of being considered as an undesired intermediate prone for catalyst deactivation during bioethanol steam reforming (ESR), acetone is suggested as a key and desired intermediate in proposed two-stage ESR processmore » that leads to high hydrogen selectivity and low methane formation on Co-based catalysts. The significance of the present work also sheds a light on controlling the chemical transformations of key intermediates in biomass conversion such as ketones. We gratefully acknowledge the financial support from U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and the Laboratory directed research and development (LDRD) project of Pacific Northwest National Laboratory (PNNL). Computing time was granted by the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). The EMSL is a U.S. DOE national scientific user facility located at PNNL, and sponsored by the U.S. DOE’s Office of Biological and Environmental Research.« less

Selective recovery of molybdenum from spent HDS catalyst using oxidative soda ash leach/carbon adsorption method.

PubMed

Park, Kyung Ho; Mohapatra, D; Reddy, B Ramachandra

2006-11-16

The petroleum refining industry makes extensive use of hydroprocessing catalysts. These catalysts contain environmentally critical and economically valuable metals such as Mo, V, Ni and Co. In the present study, a simple hydrometallurgical processing of spent hydrodesulphurization (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixture was investigated. Recovery of molybdenum was largely dependent on the concentrations of Na2CO3 and H2O2 in the reaction medium, which in turn controls the pH of leach liquor and the presence of Al and Ni as impurities. Under the optimum leaching conditions (40 g L(-1) Na2CO3, 6 vol.% H2O2, room temperature, 1h) about 85% recovery of Mo was achieved. The leach liquor was processed by the carbon adsorption method, which selectively adsorbs Mo at pH around 0.75. Desorption of Mo was selective at 15 vol.% NH4OH. With a single stage contact, it was found possible to achieve >99%, adsorption and desorption efficiency. Using this method, recovery of molybdenum as MoO3 product of 99.4% purity was achieved.

An investigation of biodiesel production from wastes of seafood restaurants.

PubMed

El-Gendy, Nour Sh; Hamdy, A; Abu Amr, Salem S

2014-01-01

This work illustrates a comparative study on the applicability of the basic heterogeneous calcium oxide catalyst prepared from waste mollusks and crabs shells (MS and CS, resp.) in the transesterification of waste cooking oil collected from seafood restaurants with methanol for production of biodiesel. Response surface methodology RSM based on D-optimal deign of experiments was employed to study the significance and interactive effect of methanol to oil M : O molar ratio, catalyst concentration, reaction time, and mixing rate on biodiesel yield. Second-order quadratic model equations were obtained describing the interrelationships between dependent and independent variables to maximize the response variable (biodiesel yield) and the validity of the predicted models were confirmed. The activity of the produced green catalysts was better than that of chemical CaO and immobilized enzyme Novozym 435. Fuel properties of the produced biodiesel were measured and compared with those of Egyptian petro-diesel and international biodiesel standards. The biodiesel produced using MS-CaO recorded higher quality than that produced using CS-CaO. The overall biodiesel characteristics were acceptable, encouraging application of CaO prepared from waste MS and CS for production of biodiesel as an efficient, environmentally friendly, sustainable, and low cost heterogeneous catalyst.

Hydroxyl-Exchanged Nanoporous Ionic Copolymer toward Low-Temperature Cycloaddition of Atmospheric Carbon Dioxide into Carbonates.

PubMed

Guo, Zengjing; Cai, Xiaochun; Xie, Jingyan; Wang, Xiaochen; Zhou, Yu; Wang, Jun

2016-05-25

An ionic copolymer catalyst with nanopores, large surface area, high ionic density, and superior basicity was prepared via the radical copolymerization of amino-functionalized ionic liquid bromide and divinylbenzene, followed with a hydroxyl exchange for removing bromonium. Evaluated in chemical fixation of CO2 with epoxides into cyclic carbonates in the absence of any solvent and basic additive, the nanoporous copolymer catalyst showed high and stable activity, superior to various control catalysts including the halogen-containing analogue. Further, high yields were obtained over a wide scope of substrates including aliphatic long carbon-chain alkyl epoxides and internal epoxide, even under atmospheric pressure and less than 100 °C for the majority of the substrates. On the basis of in situ Fourier transform infrared (FT-IR) investigation and density functional theory (DFT) calculation for the reaction intermediates, we proposed a possible reaction mechanism accounting for the superior catalytic activity of the ionic copolymer. The specifically prepared ionic copolymer material of this work features highly stable, noncorrosive, and sustainable catalysis and, thus, may be a new possibility for efficient chemical fixation of CO2 since it is an environmentally friendly, metal-free solid catalyst.

Modularized and water-cooled photo-catalyst cleaning devices for aquaponics based on ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Yang, Henglong; Lung, Louis; Wei, Yu-Chien; Huang, Yi-Bo; Chen, Zi-Yu; Chou, Yu-Yang; Lin, Anne-Chin

2017-08-01

The feasibility of applying ultraviolet light-emitting diodes (UV-LED's) as triggering sources of photo-catalyst based on titanium dioxide (TiO2) nano-coating specifically for water-cleaning process in an aquaponics system was designed and proposed. The aquaponics system is a modern farming system to integrate aquaculture and hydroponics into a single system to establish an environmental-friendly and lower-cost method for farming fish and vegetable all together in urban area. Water treatment in an aquaponics system is crucial to avoid mutual contamination. we proposed a modularized watercleaning device composed of all commercially available components and parts to eliminate organic contaminants by using UV-LED's for TiO2 photo-catalyst reaction. This water-cleaning module consisted of two coaxial hollowed cylindrical pipes can be submerged completely in water for water treatment and cooling UV-LED's. The temperature of the UV-LED after proper thermal management can be reduced about 16% to maintain the optimal operation condition. Our preliminary experimental result by using Methylene Blue solution to simulate organic contaminants indicated that TiO2 photo-catalyst triggered by UV-LED's can effectively decompose organic compound and decolor Methylene Blue solution.

DEVELOPMENT OF A RECYCLABLE HETEROGENEOUS CATALYST FOR BIODIESEL SYNTHESIS UTILIZING WASTE GREASE AS FEEDSTOCK

EPA Science Inventory

As fuel consumption continues depleting nonrenewable energy sources and environmental health concerns heighten due to its use, a movement toward sustainable alternatives is necessary for the stewardship of future generations. Biodiesel (BD) is one renewable resource being deve...

TEST REPORT OF MOBILE SOURCE EMISSIONS CONTROL DEVICES DONALDSON COMPANY INC.SERIES 6100 DIESEL OXIDATION CATALYST MUFFLER AND SPIRACLE CLOSED CRANKCASE FILTRATION SYSTEM

EPA Science Inventory

This report is on an environmental verification of the emissions characteristics of a Donaldson Corp. catalytic muffler and catalyic crankcase emissions control. It was found the systems reduced emissions.

CONTROL TECHNOLOGIES: PILOT- & FULL-SCALE TESTS

EPA Science Inventory

Two different project are to be supported in FY03. The first project is being conducted by the North Dakota Energy and Environmental Research Center (ND-EERC). This project consists of tests on coal-fired utility boilers to determine the effects of SCR catalysts and ammonia in...

Catalytic potential of selected metal ions for bioleaching, and potential techno-economic and environmental issues: A critical review.

PubMed

Pathak, Ashish; Morrison, Liam; Healy, Mark Gerard

2017-04-01

Bioleaching is considered to be a low-cost, eco-friendly technique for leaching valuable metals from a variety of matrixes. However, the inherent slow dissolution kinetics and low metal leaching yields have restricted its wider commercial applicability. Recent advancements in bio-hydrometallurgy have suggested that these critical issues can be successfully alleviated through the addition of a catalyst. The catalyzing properties of a variety of metals ions (Ag + , Hg ++ , Bi +++ , Cu ++ , Co ++ etc.) during bioleaching have been successfully demonstrated. In this article, the role and mechanisms of these metal species in catalyzing bioleaching from different minerals (chalcopyrite, complex sulfides, etc.) and waste materials (spent batteries) are reviewed, techno-economic and environmental challenges associated with the use of metals ions as catalysts are identified, and future prospectives are discussed. Based on the analysis, it is suggested that metal ion-catalyzed bioleaching will play a key role in the development of future industrial bio-hydrometallurgical processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fitness decline under osmotic stress in Caenorhabditis elegans populations subjected to spontaneous mutation accumulation at varying population sizes.

PubMed

Katju, Vaishali; Packard, Lucille B; Keightley, Peter D

2018-04-01

The consequences of mutations for population fitness depends on their individual selection coefficients and the effective population size. An earlier study of Caenorhabditis elegans spontaneous mutation accumulation lines evolved for 409 generations at three population sizes found that N e   = 1 populations declined significantly in fitness whereas the fitness of larger populations (N e   = 5, 50) was indistinguishable from the ancestral control under benign conditions. To test if larger MA populations harbor a load of cryptic deleterious mutations that are obscured under benign laboratory conditions, we measured fitness under osmotic stress via exposure to hypersaline conditions. The fitness of N e   = 1 lines exhibited a further decline under osmotic stress compared to benign conditions. However, the fitness of larger populations remained indistinguishable from that of the ancestral control. The average effects of deleterious mutations in N e   = 1 lines were estimated to be 22% for productivity and 14% for survivorship, exceeding values previously detected under benign conditions. Our results suggest that fitness decline is due to large effect mutations that are rapidly removed via selection even in small populations, with implications for conservation practices. Genetic stochasticity may not be as potent and immediate a threat to the persistence of small populations as other demographic and environmental stochastic factors. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Heterolytic Activation of Hydrogen Promoted by Ruthenium Nanoparticles immobilized on Basic Supports and Hydrogenation of Aromatic Compounds

NASA Astrophysics Data System (ADS)

Fang, Minfeng

Despite the aggressive development and deployment of new renewable and nuclear technologies, petroleum-derived transportation fuels---gasoline, diesel and jet fuels---will continue to dominate the markets for decades. Environmental legislation imposes severe limits on the tolerable proportion of aromatics, sulfur and nitrogen contents in transportation fuels, which is difficult to achieve with current refining technologies. Catalytic hydrogenation plays an important role in the production of cleaner fuels, both as a direct means to reduce the aromatics and as a key step in the hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) processes. However, conventional catalysts require drastic conditions and/or are easily poisoned by S or N aromatics. Therefore, there is still a need for new efficient catalysts for hydrogenation reactions relevant to the production of cleaner fossil fuels. Our catalyst design involves metallic nanoparticles intimately associated with a basic support, with the aim of creating a nanostructure capable of promoting the heterolytic activation of hydrogen and ionic hydrogenation mechanisms, as a strategy to avoid catalyst poisoning and enhance catalytic activity. We have designed and prepared a new nanostructured catalytic material composed of RuNPs immobilized on the basic polymer P4VPy. We have demonstrated that the Ru/P4VPy catalyst can promote heterolytic hydrogen activation and a unique surface ionic hydrogenation mechanism for the efficient hydrogenation of N-aromatics. This is the first time these ionic hydrogenation pathways have been demonstrated on solid surfaces. For the RuNPs surfaces without basic sites in close proximity, the conventional homolytic H2 splitting is otherwise involved. Using the mechanistic concepts from Ru/P4VPy, we have designed and prepared the Ru/MgO catalyst, with the aim to improve the catalytic efficiency for the hydrogenation of heteroatom aromatics operating by the ionic hydrogenation mechanism. The Ru/MgO catalyst significantly improves the catalytic efficiency for hydrogenation of a variety of N-/S-heteroaromatics and mono-/polycyclic aromatic hydrocarbons representative of components of petroleum-derived fuels. The catalyst is superior to the few other known supported noble metal catalysts for these reactions. Mechanistic studies also point to the ionic hydrogenation mechanism on the Ru/MgO surfaces. In addition, the Ru/MgO catalyst is highly recyclable and long-lived.

Habitual and value-guided purchase behavior.

PubMed

Biel, Anders; Dahlstrand, Ulf; Grankvist, Gunne

2005-06-01

Society increasingly requests that individuals adopt environmentally benign behavior. Information campaigns purported to change people's attitudes are often regarded as prerequisites to installing such changes. While such information may be a necessary step, it is not sufficient by itself. We argue that many everyday behaviors with environmental consequences are habitual, and that little attention is given to information directed toward changing these habitual behaviors. In other instances, behavior is guided by values in a more reflective process. However, other information besides environmental consequences may draw a person's attention and affect behavioral choice. Using surveys and experimental studies targeting consumer behavior, we studied under what conditions different kinds of information is likely to influence people with varying levels of environmental concern. Based on results from these studies, implications for behavioral change are discussed.

Influence of copper on nickel-based catalysts in the conversion of glycerol

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

Miranda, Barbara C.; Chimentao, Ricardo J.; Szanyi, Janos

2015-05-01

The catalytic transformation of glycerol to value-added compounds was investigated over bimetallic Ni-Cu/γ-Al2O3 catalysts with Ni/Cu atomic ratios of 8/1, 4/1, 2/1, 1/1, 1/2, 1/4, and 1/8. XPS analysis revealed that the surface composition of the catalyst exhibited progressive enrichment of Cu as its content in the catalyst increased. H2-chemisorption indicated that the total number of exposed Ni atoms decreased as the Cu content increased. As a result, deep hydrogenolysis to produce CH4 was inhibited by the addition of Cu to the Ni catalyst, yielding higher selectivity towards the dehydration products of glycerol such as hydroxyacetone. FTIR spectra of adsorbedmore » CO reveals that Cu asserts both geometric and electronic effects on the adsorption properties of Ni. The geometrical effect is visualized by the progressive disappearance of the bridge-bound adsorbed CO on metallic Ni by the incorporation of Cu. This suggests that the deep hydrogenolysis of glycerol to CH4 formation requires an ensemble of adjacent active Ni atoms. The electronic effect of Cu on Ni is indicated by the red shift of the IR peak of adsorbed CO as the Cu content increases. The electronic interaction between Cu and Ni species was also substantiated by XANES results. HTREM revealed metal particles very well distributed on the support with particle size of 1.5 to 5 nm. The Ni-Cu samples were not a total intermetallic alloys. We also gratefully acknowledge the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division for the support of this work. The research related to the FTIR of adsorption of CO (Proposal 48209) was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle Memorial Institute under contract number DE-AC05-76RL01830.« less

Effects of Si/Al Ratio on Cu/SSZ-13 NH3-SCR Catalysts: Implications for the active Cu species and the Roles of Brønsted Acidity

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

Gao, Feng; Washton, Nancy M.; Wang, Yilin

2015-09-03

Cu/SSZ-13 catalysts with three Si/Al ratios of 6, 12 and 35 were synthesized with Cu incorporation via solution ion exchange. The implications of varying Si/Al ratios on the nature of the multiple Cu species that can be present in the SSZ-13 zeolite are a major focus of this work, as highlighted by the results of a variety of catalyst characterization and reaction kinetics measurements. Specifically, catalysts were characterized with surface area/pore volume measurements, temperature programmed reduction by H2 (H2-TPR), NH3 temperature programmed desorption (NH3-TPD), and DRIFTS and solid-state nuclear magnetic resonance (NMR) spectroscopies. Catalytic properties were examined using NO oxidation,more » ammonia oxidation, and standard ammonia selective catalytic reduction (NH3-SCR) reactions on selected catalysts under differential conditions. Besides indicating possible variably active multiple Cu species for these reactions, the measurements are also used to untangle some of the complexities caused by the interplay between redox of Cu ion centers and Brønsted acidity. All three reactions appear to follow a redox reaction mechanism, yet the roles of Brønsted acidity are quite different. For NO oxidation, increasing Si/Al ratio lowers Cu redox barriers, thus enhancing reaction rates. Brønsted acidity appears to play essentially no role for this reaction. For standard NH3-SCR, residual Brønsted acidity plays a significant beneficial role at both low- and high-temperature regimes. For NH3 oxidation, no clear trend is observed suggesting both Cu ion center redox and Brønsted acidity play important and perhaps competing roles. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less

Part I. Improved flame retardant textiles. Part II. Novel approach to layer-by-layer processing for flame retardant textiles.

USDA-ARS?s Scientific Manuscript database

In this presentation, new approaches for flame retardant textile by using supercritical carbon dioxide (scCO2) and layer-by-layer processing will be discussed. Due to its environmentally benign character, the scCO2 is considered in green chemistry as a substitute for organic solvents in chemical re...

Self-assembly of palladium nanoparticles: Synthesis of nanobelts, nanoplates and nanotrees using vitamin B1 and their application in carbon-carbon coupling reactions

EPA Science Inventory

An environmentally friendly one-step method to synthesize palladium (Pd) nanobelts, nanoplates and nanotrees using vitamin B1 without using any special capping agents at room temperature is described. This greener method, which uses water as benign solvent and vitamin B1 as a red...

A rapid, one-pot, microwave-influenced synthesis of spiro-2,5-diketopiperazines via a cascade Ugi/6-exo-trig aza-Michael reaction.

PubMed

Santra, Soumava; Andreana, Peter R

2011-04-01

A rapid, cascade reaction process has been developed to access biologically validated spiro-2,5-diketopiperazines. The facile and environmentally benign method capitalizes on commercially available starting reagents for a sequential Ugi/6-exo-trig aza-Michael reaction, water as a solvent, and microwave irradiation without any extraneous additives.

Department of the Navy 1994 Posture Statement. ’Revolutionizing Our Naval Forces’

DTIC Science & Technology

1994-01-01

heavy metals . "* Marine biochemistry and remediation of harbor sediments . "* Vessel anti-fouling coatings based on environmentally benign compounds...Naval: and Coast Guard assets, often in company with foreign navies, are performing Maritime Interception Operations in-theRed Sea and Northern Arabian ...FROM THE SEA : NAVAL FORCES IN ACTION ......................... 7 NATIONAL COMMAND AUTHORITIES ................................. 8

Barriers and Bridges to the Integration of Social-ecological Resilience and Law

EPA Science Inventory

There is a fundamental rift between how ecologists and lawyers view uncertainty. In the study of ecology, uncertainty is a catalyst for exploration. However, uncertainty is antithetical to the rule of law. This issue is particularly troubling in environmental management, where th...

The effects of ferrocene concentration on soot in an ethylene laminar diffusion flame

EPA Science Inventory

Metal fuel-borne catalysts are of interest in the combustion and environmental communities due principally to their ability to reduce carbon particulate mass emissions. However, a negative aspect to their use is the potential emission of the metals themselves. Post-combustion, th...

Nanoscale Zero-Valent Iron (NZVI) supported on sineguelas waste for Pb(II) removal from aqueous solution: kinetics, thermodynamic and mechanism.

PubMed

Arshadi, M; Soleymanzadeh, M; Salvacion, J W L; SalimiVahid, F

2014-07-15

In this study, the synthesis and characterization of a new adsorbent containing nanoscale zerovalent iron particles (NZVI) decorated sineguelas waste (S-NaOH-NZVI) from agriculture biomass was investigated for the adsorption/reduction of inorganic pollution such as Pb(II) ions. The combination of ZVI particles on the surface of sineguelas waste can help to overcome the disadvantage of ultra-fine powders which may have strong tendency to agglomerate into larger particles, resulting in an adverse effect on both effective surface area and catalyst performance. The synthesized materials were characterized with different methods such as FT-IR, BET, XRD, TEM and pHPZC. Good dispersion of NZVI particles (ca. 10-70nm) on the sineguelas waste was observed. The effects of various parameters, such as contact time, pH, concentration, adsorbent dosage and temperature were studied. The adsorption of Pb(II) ions has been studied in terms of pseudo-first- and second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-second-order equation. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption of Pb(II) ions were feasible, spontaneous and endothermic at 25-80°C. XRD analysis indicated the presence of Pb(0) on the S-NaOH-NZVI surface. This study suggests that the modified sineguelas waste by NZVI particles can be prepared at low cost and the materials are environmentally benign for the removal of Pb(II) ions, and likely many other heavy metal ions, from water. Copyright © 2014 Elsevier Inc. All rights reserved.

Growing green electricity: progress and strategies for use of photosystem I for sustainable photovoltaic energy conversion.

PubMed

Nguyen, Khoa; Bruce, Barry D

2014-09-01

Oxygenic photosynthesis is driven via sequential action of Photosystem II (PSII) and (PSI)reaction centers via the Z-scheme. Both of these pigment-membrane protein complexes are found in cyanobacteria, algae, and plants. Unlike PSII, PSI is remarkably stable and does not undergo limiting photo-damage. This stability, as well as other fundamental structural differences, makes PSI the most attractive reaction centers for applied photosynthetic applications. These applied applications exploit the efficient light harvesting and high quantum yield of PSI where the isolated PSI particles are redeployed providing electrons directly as a photocurrent or, via a coupled catalyst to yield H₂. Recent advances in molecular genetics, synthetic biology, and nanotechnology have merged to allow PSI to be integrated into a myriad of biohybrid devices. In photocurrent producing devices, PSI has been immobilized onto various electrode substrates with a continuously evolving toolkit of strategies and novel reagents. However, these innovative yet highly variable designs make it difficult to identify the rate-limiting steps and/or components that function as bottlenecks in PSI-biohybrid devices. In this study we aim to highlight these recent advances with a focus on identifying the similarities and differences in electrode surfaces, immobilization/orientation strategies, and artificial redox mediators. Collectively this work has been able to maintain an annual increase in photocurrent density (Acm⁻²) of ~10-fold over the past decade. The potential drawbacks and attractive features of some of these schemes are also discussed with their feasibility on a large-scale. As an environmentally benign and renewable resource, PSI may provide a new sustainable source of bioenergy. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2013. Published by Elsevier B.V.

Early-Late Heterobimetallic Complexes Linked by Phosphinoamide Ligands. Tuning Redox Potentials and Small Molecule Activation

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

Thomas, Christine M.

2015-08-01

Recent attention in the chemical community has been focused on the energy efficient and environmentally benign conversion of abundant small molecules (CO2, H2O, etc.) to useful liquid fuels. This project addresses these goals by examining fundamental aspects of catalyst design to ultimately access small molecule activation processes under mild conditions. Specifically, Thomas and coworkers have targetted heterobimetallic complexes that feature metal centers with vastly different electronic properties, dictated both by their respective positions on the periodic table and their coordination environment. Unlike homobimetallic complexes featuring identical or similar metals, the bonds between metals in early/late heterobimetallics are more polarized, withmore » the more electron-rich late metal center donating electron density to the more electron-deficient early metal center. While metal-metal bonds pose an interesting strategy for storing redox equivalents and stabilizing reactive metal fragments, the polar character of metal-metal bonds in heterobimetallic complexes renders these molecules ideally poised to react with small molecule substrates via cleavage of energy-rich single and double bonds. In addition, metal-metal interactions have been shown to dramatically affect redox potentials and promote multielectron redox activity, suggesting that metal-metal interactions may provide a mechanism to tune redox potentials and access substrate reduction/activation at mild overpotentials. This research project has provided a better fundamental understanding of how interactions between transition metals can be used as a strategy to promote and/or control chemical transformations related to the clean production of fuels. While this project focused on the study of homogeneous systems, it is anticipated that the broad conclusions drawn from these investigations will be applicable to heterogeneous catalysis as well, particularly on heterogeneous processes that occur at interfaces in multicomponent systems.« less

Citrus Juice: Green and Natural Catalyst for the Solvent-free Silica Supported Synthesis of β-Enaminones Using Grindstone Technique.

PubMed

Marvi, Omid; Fekri, Leila Zare

2018-01-01

Citrus Juice as an efficient, cost-effective and green catalyst employed for one-pot synthesis of various β-substituted enaminones through the reaction of β- dicarbonyl compounds with different primary amines in a solvent-free conditions on silica gel as solid surface using grindstone technique in high yields and short reaction times. The presented procedure is operationally simple, practical and green. The wide application of this procedure is demonstrated by the use of various substituted amines to react with β-dicarbonyl compounds. The method was successfully applied for primary amines (15 entries) and the related enaminones were well synthesized in good to excellent yields. Melting points were measured on an Electro thermal 9100 apparatus. 1HNMR and 13C NMR spectra were recorded on a FTNMR BRUKER DRX 500 Avence spectrometer. Chemical shifts were given in ppm from TMS as internal references and CDCl3 was used as the solvent as well. The IR spectra were recorded on a Perkin Elmer FT-IR GX instrument. The chemicals used in this work were purchased from Merck and Fluka chemical companies. Grinding synthesis of citrus juice catalyzed enamination of 1,3-dicarbonyls (acetylacetone, methyl and ethyl-3-oxobutanoate) with various primary amines (aromatic and aliphatic) under solvent-free silica supported conditions was examined and studied (15 entries) and the obtained enaminones were well synthesized in good to excellent yields. Furthermore, the effect of various catalysts on the yield and reaction time for grinding synthesis of 3-phenylamino- but- 2- enoic acid ethyl ester (1) by this method has evaluated as well. A novel, efficient and green protocol for the grinding synthesis of enaminones using citrus juice as natural catalyst has been presented. This methodology is user friendly, green and low cost procedure under mild reaction condition with faster reaction rates. The citrus juice is inexpensive and non-toxic which makes the process convenient, more economic and benign. Furthermore, applying grindstone technique in solvent-free conditions, use of silica gel as a solid and heterogeneous surface in reaction, high yields of products, cleaner reaction profiles, and availability of the reagents makes this method a better choice for synthetic chemists. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Reversible Hydrogenation of Carbon Dioxide to Formic Acid and Methanol: Lewis Acid Enhancement of Base Metal Catalysts.

PubMed

Bernskoetter, Wesley H; Hazari, Nilay

2017-04-18

New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H 2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H 2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H 2 ) and methanol (MeOH, 12.6 wt % H 2 ) can be obtained renewably and are excellent prospective liquid CHS materials. In addition, MeOH has considerable potential both as a direct replacement for gasoline and as a fuel cell input. The current commercial syntheses of FA and MeOH, however, use nonrenewable feedstocks and will not facilitate the use of these molecules for CHS. An appealing option for the sustainable synthesis of both FA and MeOH, which could be implemented on a large scale, is the direct metal catalyzed hydrogenation of CO 2 . Furthermore, given that CO 2 is a readily available, nontoxic and inexpensive source of carbon, it is expected that there will be economic and environmental benefits from using CO 2 as a feedstock. One strategy to facilitate both the dehydrogenation of FA and MeOH and the hydrogenation of CO 2 and H 2 to FA and MeOH is to utilize a homogeneous transition metal catalyst. In particular, the development of catalysts based on first row transition metals, which are cheaper, and more abundant than their precious metal counterparts, is desirable. In this Account, we describe recent advances in the development of iron and cobalt systems for the hydrogenation of CO 2 to FA and MeOH and the dehydrogenation of FA and MeOH and provide a brief comparison between precious metal and base metal systems. We highlight the different ligands that have been used to stabilize first row transition metal catalysts and discuss the use of additives to promote catalytic activity. In particular, the Account focuses on the crucial role that alkali metal Lewis acid cocatalysts can play in promoting increased activity and catalyst stability for first row transition metal systems. We relate these effects to the nature of the elementary steps in the catalytic cycle and describe how the Lewis acids stabilize the crucial transition states. For all four transformations, we discuss in detail the currently proposed catalytic pathways, and throughout the Account we identify mechanistic similarities among catalysts for the four processes. The limitations of current catalytic systems are detailed, and suggestions are provided on the improvements that are likely required to develop catalysts that are more stable, active, and practical.

Prototype Scale Development of an Environmentally Benign Yellow Smoke Hand-Held Signal Formulation Based on Solvent Yellow 33

DTIC Science & Technology

2013-04-15

VAAR) was purchased from McGean. Hydrated basic magnesium carbonate was obtained from Pine Bluff Arsenal (Pine Bluff, AR) and was confirmed to be Mg5( CO3 ...a potential environmental exposure of approximately 29 g of the toxic yellow dyes throughout the life cycle of a single M194 signal! To mitigate this...consists of Solvent Yellow 33 as the smoke sublimating agent, hydrated basic magnesium carbonate (Mg5( CO3 )4(OH)2·4H2O) instead of sodium bicarbonate (NaHCO3

[Methodological approaches to the development of environmentally benign technology for the use of solid waste in iron metallurgy].

PubMed

Pugin, K G; Vaĭsman, Ia I

2013-01-01

On the basis of the life cycle of materials, containing wastes of iron and steel industry, new methodological approaches to the assessment of technologies of the secondary use of wastes are developed A complex criteria for selection of the technology for the use of resource potential of solid waste of iron and steel industry are developed with taking into account environmental, technological and economic indices. The technology of the use of wastes of ferrovanadium industry as bulk solid materials at the solid waste landfill is shown.

Mathematical modeling of methyl ester concentration distribution in a continuous membrane tubular reactor and comparison with conventional tubular reactor

NASA Astrophysics Data System (ADS)

Talaghat, M. R.; Jokar, S. M.; Modarres, E.

2017-10-01

The reduction of fossil fuel resources and environmental issues made researchers find alternative fuels include biodiesels. One of the most widely used methods for production of biodiesel on a commercial scale is transesterification method. In this work, the biodiesel production by a transesterification method was modeled. Sodium hydroxide was considered as a catalyst to produce biodiesel from canola oil and methanol in a continuous tubular ceramic membranes reactor. As the Biodiesel production reaction from triglycerides is an equilibrium reaction, the reaction rate constants depend on temperature and related linearly to catalyst concentration. By using the mass balance for a membrane tubular reactor and considering the variation of raw materials and products concentration with time, the set of governing equations were solved by numerical methods. The results clearly show the superiority of membrane reactor than conventional tubular reactors. Afterward, the influences of molar ratio of alcohol to oil, weight percentage of the catalyst, and residence time on the performance of biodiesel production reactor were investigated.

Insights into perfluorooctane sulfonate photodegradation in a catalyst-free aqueous solution

PubMed Central

Lyu, Xian-Jin; Li, Wen-Wei; Lam, Paul K. S.; Yu, Han-Qing

2015-01-01

Photodegradation in the absence of externally added chemicals could be an attractive solution for the removal of perfluorooctane sulfonate (PFOS) in aqueous environment, but the low decomposition rate presents a severe challenge and the underlying mechanisms are unclear. In this study, we demonstrated that PFOS could be effectively degraded in a catalyst-free aqueous solution via a reduction route. Under appropriate pH and temperature conditions, a rapid PFOS photodegradation, with a pseudo-first-order decomposition rate constant of 0.91 h−1, was achieved. In addition, hydrated electrons were considered to be the major photo-generated reductive species responsible for PFOS photodegradation in this system. Its production and reduction ability could be significantly affected by the environmental conditions such as pH, temperature and presence of oxidative species. This study gives insights into the PFOS photodegradation process and may provide useful information for developing catalyst-free photodegradation systems for decomposing PFOS and other persistent water contaminants. PMID:25879866

Achieving Simultaneous CO2 and H2 S Conversion via a Coupled Solar-Driven Electrochemical Approach on Non-Precious-Metal Catalysts.

PubMed

Ma, Weiguang; Wang, Hong; Yu, Wei; Wang, Xiaomei; Xu, Zhiqiang; Zong, Xu; Li, Can

2018-03-19

Carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) are generally concomitant with methane (CH 4 ) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO 2 and H 2 S into value-added products is attractive; however it has not received enough attention. A solar-driven electrochemical process is demonstrated using graphene-encapsulated zinc oxide catalyst for CO 2 reduction and graphene catalyst for H 2 S oxidation mediated by EDTA-Fe 2+ /EDTA-Fe 3+ redox couples. The as-prepared solar-driven electrochemical system can realize the simultaneous conversion of CO 2 and H 2 S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transformation of Unsaturated Fatty Acids/Esters to Corresponding Keto Fatty Acids/Esters by Aerobic Oxidation with Pd(II)/Lewis Acid Catalyst.

PubMed

Senan, Ahmed M; Zhang, Sicheng; Zeng, Miao; Chen, Zhuqi; Yin, Guochuan

2017-08-16

Utilization of renewable biomass to partly replace the fossil resources in industrial applications has attracted attention due to the limited fossil feedstock with the increased environmental concerns. This work introduced a modified Wacker-type oxidation for transformation of unsaturated fatty acids/esters to the corresponding keto fatty acids/esters, in which Cu 2+ cation was replaced with common nonredox metal ions, that is, a novel Pd(II)/Lewis acid (LA) catalyst. It was found that adding nonredox metal ions can effectively promote Pd(II)-catalyzed oxidation of unsaturated fatty acids/esters to the corresponding keto fatty acids/esters, even much better than Cu 2+ , and the promotional effect is highly dependent on the Lewis acidity of added nonredox metal ions. The improved catalytic efficiency is attributed to the formation of heterobimetallic Pd(II)/LA species, and the oxidation mechanism of this Pd(II)/LA catalyst is also briefly discussed.

Catalytic behavior of metal catalysts in high-temperature RWGS reaction: In-situ FT-IR experiments and first-principles calculations

PubMed Central

Choi, Sungjun; Sang, Byoung-In; Hong, Jongsup; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Hyoungchul

2017-01-01

High-temperature chemical reactions are ubiquitous in (electro) chemical applications designed to meet the growing demands of environmental and energy protection. However, the fundamental understanding and optimization of such reactions are great challenges because they are hampered by the spontaneous, dynamic, and high-temperature conditions. Here, we investigated the roles of metal catalysts (Pd, Ni, Cu, and Ag) in the high-temperature reverse water-gas shift (RWGS) reaction using in-situ surface analyses and density functional theory (DFT) calculations. Catalysts were prepared by the deposition-precipitation method with urea hydrolysis and freeze-drying. Most metals show a maximum catalytic activity during the RWGS reaction (reaching the thermodynamic conversion limit) with formate groups as an intermediate adsorbed species, while Ag metal has limited activity with the carbonate species on its surface. According to DFT calculations, such carbonate groups result from the suppressed dissociation and adsorption of hydrogen on the Ag surface, which is in good agreement with the experimental RWGS results. PMID:28120896

Green synthesis of the Pd nanoparticles supported on reduced graphene oxide using barberry fruit extract and its application as a recyclable and heterogeneous catalyst for the reduction of nitroarenes.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Alizadeh, Mohammad; Bagherzadeh, Mojtaba

2016-03-15

Through this manuscript the green synthesis of palladium nanoparticles supported on reduced graphene oxide (Pd NPs/RGO) under the mild conditions through reduction of the graphene oxide and Pd(2+) ions using barberry fruit extract as reducing and stabilizing agent is reported. The as-prepared Pd NPs/RGO was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The Pd NPs/RGO could be used as an efficient and heterogeneous catalyst for reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2015 Elsevier Inc. All rights reserved.

A novel protocol for solvent-free synthesis of 4,6-diaryl-3,4-dihydropyrimidine-2(1H)-ones catalyzed by metal oxide-MWCNTs nanocomposites

NASA Astrophysics Data System (ADS)

Safari, Javad; Gandomi-Ravandi, Soheila

2014-09-01

A Biginelli-like condensation is described using acetophenone as active methylene compound with aldehydes and urea to furnish pyrimidinone analogues under solvent-free conditions. In this paper, besides the preparation of nanocomposites based on MWCNTs, our investigations have been focused on the catalytic efficiency of metal oxide-MWCNTs composites. The requisites of a good catalyst are high activity, selectivity, reusability, reasonable cost and long lifetime. The application of solvent-free conditions and transition metal oxides decorated-MWCNTs (MOx-MWCNTs) nanocomposites as attractive, effective and reusable catalysts leads to the efficient synthesis of 4,6-diaryl-3,4-dihydropyrimidin-2-(1H)-ones. This recyclable heterogeneous catalytic system provides a simple strategy to generate a variety of pyrimidinones under solvent-free conditions. Utilization of easy reaction condition, recyclable green catalyst, reduced environmental impacts and simple work-up make this methodology as an interesting option for the eco-friendly synthesis of Biginelli-like compounds.

Catalytic behavior of metal catalysts in high-temperature RWGS reaction: In-situ FT-IR experiments and first-principles calculations.

PubMed

Choi, Sungjun; Sang, Byoung-In; Hong, Jongsup; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Hyoungchul

2017-01-25

High-temperature chemical reactions are ubiquitous in (electro) chemical applications designed to meet the growing demands of environmental and energy protection. However, the fundamental understanding and optimization of such reactions are great challenges because they are hampered by the spontaneous, dynamic, and high-temperature conditions. Here, we investigated the roles of metal catalysts (Pd, Ni, Cu, and Ag) in the high-temperature reverse water-gas shift (RWGS) reaction using in-situ surface analyses and density functional theory (DFT) calculations. Catalysts were prepared by the deposition-precipitation method with urea hydrolysis and freeze-drying. Most metals show a maximum catalytic activity during the RWGS reaction (reaching the thermodynamic conversion limit) with formate groups as an intermediate adsorbed species, while Ag metal has limited activity with the carbonate species on its surface. According to DFT calculations, such carbonate groups result from the suppressed dissociation and adsorption of hydrogen on the Ag surface, which is in good agreement with the experimental RWGS results.

Fast reductive amination by transfer hydrogenation "on water".

PubMed

Lei, Qian; Wei, Yawen; Talwar, Dinesh; Wang, Chao; Xue, Dong; Xiao, Jianliang

2013-03-18

Reductive amination of various ketones and aldehydes by transfer hydrogenation under aqueous conditions has been developed, by using cyclometallated iridium complexes as catalysts and formate as hydrogen source. The pH value of the solution is shown to be critical for a high catalytic chemoselectivity and activity, with the best pH value being 4.8. In comparison with that in organic solvents, the reductive amination in an aqueous phase is faster, and the molar ratio of the substrate to the catalyst (S/C) can be set as high as 1×10(5) , the highest S/C value ever reported in reductive amination reactions. The catalyst is easy to access and the reaction is operationally simple, allowing a wide range of ketones and aldehydes to react with various amines in high yields. The protocol provides a practical and environmental friendly new method for the synthesis of amine compounds. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zwitterionic-surfactant-stabilized palladium nanoparticles as catalysts in the hydrogen transfer reductive amination of benzaldehydes.

PubMed

Drinkel, Emma E; Campedelli, Roberta R; Manfredi, Alex M; Fiedler, Haidi D; Nome, Faruk

2014-03-21

Palladium nanoparticles (NPs) stabilized by a zwitterionic surfactant are revealed here to be good catalysts for the reductive amination of benzaldehydes using formate salts as hydrogen donors in aqueous isopropanol. In terms of environmental impact and economy, metallic NPs offer several advantages over homogeneous and traditional heterogeneous catalysts. NPs usually display greater activity due to the increased metal surface area and sometimes exhibit enhanced selectivity. Thus, it is possible to use very low loadings of expensive metal. The methodology eliminates the use of a hydrogen gas atmosphere or toxic or expensive reagents. A range of aromatic aldehydes were converted to benzylamines when reacted with primary and secondary amines in the presence of the Pd NPs, which also displayed good activity when supported on alumina. In every case, the Pd NPs could be easily recovered and reused up to three more times, and at the end of the process, the product was metal-free.

Carbon nanotubes-modified graphitic carbon nitride photocatalysts with synergistic effect of nickel(II) sulfide and molybdenum(II) disulfide co-catalysts for more efficient H2 evolution.

PubMed

Zhang, Yun-Xiao; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De

2018-09-15

This work reports effective photocatalysts which are composed of carbon nitride (CN), carbon nanotubes (CNTs), MoS 2 and NiS, for hydrogen evolution aiming at energy crises and environmental pollutions. The morphologies and optical properties of the photocatalysts were carefully characterized and their photocatalytic performance towards water reduction was studied afterwards. MoS 2 and NiS exhibit a significant synergistic effect working as co-catalysts. Compared to MoS 2 /CN nanohybrid, carbon nanotubes and NiS improved the absorption of visible light and the separation of charge carriers effectively. NiS-MoS 2 /CNTs/CN catalyst exhibits high performance for H 2 evolution and the optimized rate is 309.9 μmol·h -1 ·g -1 with no noble metals under visible light irradiation. The study demonstrates a non-noble metal photocatalyst system for effective generation of hydrogen with low cost. Copyright © 2018 Elsevier Inc. All rights reserved.

ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

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

Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua

Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wamore » Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.« less

Effect of TiO2 calcination temperature on the photocatalytic oxidation of gaseous NH3.

PubMed

Wu, Hongmin; Ma, Jinzhu; Zhang, Changbin; He, Hong

2014-03-01

Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400°C had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (< 300°C). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400°C contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Vanadium and tungsten release from V-based selective catalytic reduction diesel aftertreatment

NASA Astrophysics Data System (ADS)

Liu, Z. Gerald; Ottinger, Nathan A.; Cremeens, Christopher M.

2015-03-01

Vanadium-based selective catalytic reduction (V-SCR) catalysts are currently used for the reduction of nitrogen oxides (NOx) in worldwide diesel applications including Euro IV, V, and VI as well as U.S. nonroad Tier 4 Final. Although V-SCR catalysts are attractive because of their high NOx conversion, low cost, resistance to sulfur poisoning, and ability to reduce hydrocarbon emissions, there is concern that V-SCR washcoat material (e.g., vanadium and tungsten) and its derivatives may be released into the atmosphere, potentially harming human health and the environment. In this study, vanadium and tungsten release measurements are made with both a reactor- and engine-based approach in order to determine the potential release of these metals from diesel exhaust aftertreatment systems that contain a V-SCR catalyst. Results for a commercially available V-SCR reveal that both V and W release begin at 500 °C, and both reactor- and engine-based methods are capable of measuring qualitatively similar release. Emissions with the engine-based method are higher at all temperatures evaluated, likely due to this method's ability to capture particle-phase and vapor-phase emissions which become particle-bound after their evolution from the catalyst surface. Certification relevant data (NRTC and NRSC) from a nonroad engine is used to understand probable emissions from V-SCR aftertreatment architectures. Finally, results from a V-SCR catalyst formulated for improved thermal durability illustrate that it is possible to increase the maximum temperature for V-SCR catalysts. This comprehensive understanding of the temperature dependence of vanadium and tungsten volatility can be used to further analyze the full impact of diesel aftertreatment on exhaust emissions and their impact on human health and environmental toxicity.

Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

NASA Astrophysics Data System (ADS)

Thoa, Dao Thi Kim; Loc, Luu Cam

2017-09-01

The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.