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1

Copper-Exchanged Zeolite L Traps Oxygen  

NASA Technical Reports Server (NTRS)

Brief series of simple chemical treatments found to enhance ability of zeolite to remove oxygen from mixture of gases. Thermally stable up to 700 degrees C and has high specific surface area which provides high capacity for adsorption of gases. To increase ability to adsorb oxygen selectively, copper added by ion exchange, and copper-exchanged zeolite reduced with hydrogen. As result, copper dispersed atomically on inner surfaces of zeolite, making it highly reactive to oxygen, even at room temperature. Reactivity to oxygen even greater at higher temperatures.

Sharma, Pramod K.; Seshan, Panchalam K.

1991-01-01

2

Synthesis and characterization of nanocrystalline mordenite, high silica zeolite RHO, and copper faujasite  

NASA Astrophysics Data System (ADS)

Mordenite is a zeolite that has been used as a selective adsorbent and as a catalyst. In reactions where the diffusion of reagents into the pore system is the rate-determining step, nanoparticles of the catalyst improve the reaction rate. Mordenite with a crystal diameter smaller than 100 nm has been prepared by the modification of different synthetic parameters such as the source of aluminum, the presence of seeds, the use of low temperatures (150°C vs. 170°C), longer crystallization times (24 h vs. 96 h), and different silica to alumina ratios (10--30). The decrease in the crystal diameter of the prepared mordenite was monitored by the application of the Scherrer equation that relates the broadness of the X-ray diffraction peaks to crystal sizes. Zeolite RHO with an initial silica to alumina ratio (SAR) higher than 20 has been prepared. EDTA, citric acid, and tartaric acid have been used as complexing agents in the synthesis of zeolite RHO. Crystallization time increases (from 48 h to 900 h) with increasing the silica to alumina ratios (SAR) of the initial gel (SAR: 10.8 to 30) and by adding complexing agents. Complexing agents favor the formation of small crystals (0.8 mum) with increased silica to alumina ratio (final SAR: 4.5 vs. 4.0 without complexing agents). The products were characterized by XRD, FESEM, EDX, FTIR, and in-situ XRD. Copper containing faujasite has been successfully prepared for the first time using a direct synthesis method. Ammonium hydroxide was used to form a copper complex that was later mixed with the reacting gel. Crystallization took place at 85°C for 11 days. The copper containing faujasite obtained was characterized by XRD, FESEM, EDX, EPR, FTIR, TPR, and BET. According to the XRD pattern only FAU type zeolite was obtained. According to TPR experiments, the reduction temperature for Cu2+ ions present in Cu-FAU prepared by direct synthesis was 70 K higher than for Cu-FAU prepared by ion-exchange. This difference can be due to the different location of the copper ions in the supercages or in the sodalite cages of the faujasite.

Hincapie Palacio, Beatriz Omaira

3

Removal of zinc, copper and lead by natural zeolite—a comparison of adsorption isotherms  

Microsoft Academic Search

An uptake of zinc (Zn), copper (Cu), and lead (Pb) from aqueous solutions by ion exchange on natural zeolitic tuff has been studied. The Croatian zeolite clinoptilolite from the Donje Jesenje deposit has been used as a natural ion exchanger. The efficiency of removal is higher for Pb and Cu than for Zn ions. Measured concentrations of Si in the

J. Peri?; M. Trgo; N. Vukojevi? Medvidovi?

2004-01-01

4

A Facile Top-Down Protocol for Postsynthesis Modification of Hierarchical Aluminum-Rich MFI Zeolites.  

PubMed

High aluminum content constitutes a major hurdle for the postsynthesis modification of hierarchical zeolites. A facile protocol comprising fluorination and sequential alkaline treatment is presented for the postsynthesis modification of hierarchical Al-rich MFI zeolites. By virtue of this protocol, uniform intracrystalline mesoporosity is introduced in an Al-rich MFI zeolite (Si/Al=14.3). The obtained hierarchical zeolites exhibit a significant mesopore size distribution, centered around 6?nm, and show improved conversions in catalytic cracking of bulky aromatic molecules. The fundamental implications of the fluorination-alkaline treatment protocol are related to the formation of F-bearing tetrahedral aluminum species in the antecedent fluorination step, which alleviates the resistance of Al sites to the alkaline medium and causes Al?F complexation for regulated hydrolysis of the Al species during the alkaline treatment process. This top-down protocol and the derived mechanistic understandings are expected to be applied in the synthesis of hierarchical Al-rich zeolites with other framework topologies. PMID:25399674

Yu, Lili; Huang, Shengjun; Miao, Shu; Chen, Fucun; Zhang, Shuang; Liu, Zhenni; Xie, Sujuan; Xu, Longya

2015-01-12

5

An introduction to zeolite molecular sieves  

Microsoft Academic Search

This book covers the following topics: What is a zeolite ; Natural zeolites and their occurrence; The structure of zeolites; Zeolite structure identification and characterization; Zeolite syntheses; Zeolites as ion exchangers; Zeolites as molecular sieves and drying agents; The stabilities of zeolite structures and their modification; Zeolites as catalysts; Zeolite-like materials (Zeotypes) containing elements other than Si or Al in

A. Dyer

1988-01-01

6

Removal of Sulfur Components from Low Sulfur Gasoline Using Copper Exchanged Zeolite Y at Ambient Temperature  

SciTech Connect

Copper-exchanged zeolite Y has been shown to be an effective material for removal of a variety of sulfur species from hydrocarbon streams, and both monovalent (Cu(I)) and divalent (Cu(II)Y) materials have been claimed to be effective. In this work we discuss experiments aimed at providing a direct performance comparison between the two copper-containing materials. Cu(I)Y zeolite is somewhat more effective than Cu(II)Y in removing thiophene from various fuel blends. Capacity of both materials for thiophene diminishes markedly when aromatics and/or olefins are present, and Cu(I)Y immediately turns black on exposure to such feeds. Both materials demonstrate ability to convert thiols to disulfides at ambient temperature.

King, David L.; Li, Liyu

2006-09-15

7

Oxidation of cyclohexane over iron and copper salen complexes simultaneously encapsulated in zeolite Y  

Microsoft Academic Search

Iron and copper salen complexes have been simultaneously encapsulated in zeolite Y by using the flexible ligand method, as substantiated by infrared spectroscopy, diffuse reflectance UV–vis spectroscopy, thermo-gravimetric and differential-thermal analyses and N2 adsorption\\/desorption experiments at ?196°C. The prepared material showed much higher activity than the neat Cu(salen) and Fe(salen) or the Cu(salen)\\/Y and Fe(salen)\\/Y or their physical mixtures in

Binbin Fan; Hongyu Li; Weibin Fan; Chun Jin; Ruifeng Li

2008-01-01

8

Zeolites  

NASA Technical Reports Server (NTRS)

Zeolites are crystalline aluminosilicates that have complex framework structures. However, there are several features of zeolite crystals that make unequivocal structure determinations difficult. The acquisition of reliable structural information on zeolites is greatly facilitated by the availability of high-quality specimens. For structure determinations by conventional diffraction techniques, large single-crystal specimens are essential. Alternatively, structural determinations by powder profile refinement methods relax the constraints on crystal size, but still require materials with a high degree of crystalline perfection. Studies conducted at CAMMP (Center for Advanced Microgravity Materials Processing) have demonstrated that microgravity processing can produce larger crystal sizes and fewer structural defects relative to terrestrial crystal growth. Principal Investigator: Dr. Albert Sacco

1992-01-01

9

EXFAS electron spectroscopy as a new tool of local characterisation of copper in Cu-Beta zeolite  

Microsoft Academic Search

EXFAS spectroscopy has been applied for the first time to the study of the local characterisation of reduced copper in zeolites. The oscillating features observed beyond the Cu M2,3VV Auger transition have been isolated and analysed following the standard EXAFS procedure.

Francisco Márquez; Antonio Palomares

2001-01-01

10

Characterisation of CuMFI catalysts by temperature programmed desorption of NO and temperature programmed reduction. Effect of the zeolite Si\\/Al ratio and copper loading  

Microsoft Academic Search

Copper MFI zeolites with different Si\\/Al ratios and different copper loadings, prepared by ion exchange, were characterised by XRD, H2-TPR and NO TPD. The results indicated the existence of diverse copper species in CuMFI catalysts, such as isolated CU2+, Cu+ ions and CuO species, whose concentrations depends on the catalyst Si\\/Al ratio and copper loading. In underexchanged catalysts (catalysts with

C. Torre-Abreu; M. F. Ribeiro; C. Henriques; G. Delahay

1997-01-01

11

Copper stabilization by zeolite synthesis in polluted soils treated with coal fly ash  

Microsoft Academic Search

This paper reports on the process of zeolite formation in an agricultural soil artificially polluted by high amounts of Cu (15 mg of Cu\\/g of soil dry weight) and treated with fused coal fly ash at 30 and 60 C and how this process affects the mobility and availability of the metal. As a consequence of the treatment, the amount

Roberto Terzano; Matteo Spagnuolo; Luca Medici; Bart Vekemans; Laszlo Vincze; Koen Janssens; Pacifico Ruggiero

2005-01-01

12

Antimicrobial properties of zeolite-X and zeolite-A ion-exchanged with silver, copper, and zinc against a broad range of microorganisms.  

PubMed

Zeolites are nanoporous alumina silicates composed of silicon, aluminum, and oxygen in a framework with cations, water within pores. Their cation contents can be exchanged with monovalent or divalent ions. In the present study, the antimicrobial (antibacterial, anticandidal, and antifungal) properties of zeolite type X and A, with different Al/Si ratio, ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions were investigated individually. The study presents the synthesis and manufacture of four different zeolite types characterized by scanning electron microscopy and X-ray diffraction. The ion loading capacity of the zeolites was examined and compared with the antimicrobial characteristics against a broad range of microorganisms including bacteria, yeast, and mold. It was observed that Ag(+) ion-loaded zeolites exhibited more antibacterial activity with respect to other metal ion-embedded zeolite samples. The results clearly support that various synthetic zeolites can be ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions to acquire antimicrobial properties or ion-releasing characteristics to provide prolonged or stronger activity. The current study suggested that zeolite formulations could be combined with various materials used in manufacturing medical devices, surfaces, textiles, or household items where antimicrobial properties are required. PMID:24242073

Demirci, Selami; Ustao?lu, Zeynep; Y?lmazer, Gonca Alt?n; Sahin, Fikrettin; Baç, Nurcan

2014-02-01

13

Copper stabilization by zeolite synthesis in polluted soils treated with coal fly ash.  

PubMed

This study deals with the process of zeolite formation in an agricultural soil artificially polluted by high amounts of Cu (15 mg of Cu/g of soil dry weight) and treated with fused coal fly ash at 30 and 60 degrees C and how this process affects the mobility and availability of the metal. As a consequence of the treatment, the amount of dissolved Cu, and thus its mobility, was strongly reduced, and the percentage of the metal stabilized in the solid phase increased over time, reaching values of 30% at 30 degrees C and 40% at 60 degrees C. The physicochemical phenomena responsible for Cu stabilization in the solid phase have been evaluated by EDTA sequential extractions and synchrotron radiation based X-ray microanalytical techniques. These techniques were used for the visualization of the spatial distribution and the speciation of Cu in and/or on the neo-formed zeolite particles. In particular, micro XRF (X-ray fluorescence) tomography showed direct evidence that Cu can be entrapped as clusters inside the porous zeolitic structures while mu-XANES (X-ray absorption near edge structure) spectroscopy determinations revealed Cu to be present mainly as Cu(ll) hydroxide and Cu(ll) oxide. The reported results could be useful as a basic knowledge for planning new technologies for the on site physicochemical stabilization of heavy metals in heavily polluted soils. PMID:16173593

Terzano, Roberto; Spagnuolo, Matteo; Medici, Luca; Vekemans, Bart; Vincze, Laszlo; Janssens, Koen; Ruggiero, Pacifico

2005-08-15

14

Copper stabilization by zeolite synthesis in polluted soils treated with coal fly ash  

SciTech Connect

This paper reports on the process of zeolite formation in an agricultural soil artificially polluted by high amounts of Cu (15 mg of Cu/g of soil dry weight) and treated with fused coal fly ash at 30 and 60 C and how this process affects the mobility and availability of the metal. As a consequence of the treatment, the amount of dissolved Cu, and thus its mobility, was strongly reduced, and the percentage of the metal stabilized in the solid phase increased over time, reaching values of 30% at 30{sup o}C and 40% at 60{sup o}C. The physicochemical phenomena responsible for Cu stabilization in the solid phase have been evaluated by EDTA sequential extractions and synchrotron radiation based X-ray microanalytical techniques. These techniques were used for the visualization of the spatial distribution and the speciation of Cu in and/or on the neo-formed zeolite particles. In particular, micro XRF (X-ray fluorescence) tomography showed direct evidence that Cu can be entrapped as clusters inside the porous zeolitic structures while -{mu}XANES (X-ray absorption near edge structure) spectroscopy determinations revealed Cu to be present mainly as Cu(II) hydroxide and Cu(II) oxide. The reported results could be useful as a basic knowledge for planning new technologies for the on-site physicochemical stabilization of heavy metals in heavily polluted soils. 32 refs., 5 figs.

Roberto Terzano; Matteo Spagnuolo; Luca Medici; Bart Vekemans; Laszlo Vincze; Koen Janssens; Pacifico Ruggiero [University of Bari, Bari (Italy). Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale

2005-08-15

15

Modification on natural clinoptilolite zeolite for its NH4+ retention capacity.  

PubMed

The scope of this study was to modify the natural clinoptilolite zeolite available locally (Akita Prefecture, Japan) for its ammonium ions retention capacity. The natural clinoptilolite was modified chemically and mechanically with changing time duration of sodium hydroxide treatment and ball to powder mass ratio in wet ball milling, respectively. The ammonium ions retention capacity of thus obtained modified clinoptilolites were found to sharply increase with either increasing alkaline metal cations content or increasing specific surface area (decreasing particle size) of the clinoptilolite. The main mechanism of ammonium ions retention is ion exchange and Na(+) ions were observed to be more easily exchanged for ammonium ions. The sorption isotherms were good fit to the Langmuir model in the cases of natural and chemically modified clinoptilolites while Freundlich model was favorable in the case of mechanically modified clinoptilolites. The maximum NH(4)(+) retention capacities of natural clinoptilolite (NZeo), clinoptilolite treated with NaOH solution for 72h (Zeo-72) and wet-milled clinoptilolite (WM-50) according to Langmuir model were 0.89, 1.15 and 1.39 mmol/g, respectively. The overall reaction is pseudo-second-order with rate constant of 3.6 x 10(-2)dm(3)g/(mmol min). It was possible to enhance the NH(4)(+) retention capacity of natural clinoptilolite just by decreasing particle size without incorporating any further exchangeable cations within the framework of zeolite. PMID:19395165

Jha, Vinay Kumar; Hayashi, Shigeo

2009-09-30

16

Surface modification of calcium-copper hydroxyapatites using polyaspartic acid  

NASA Astrophysics Data System (ADS)

Mixed calcium-copper hydroxyapatite (Ca-CuHAp), with general formula Ca(10-x)Cux(PO4)6(OH)2, where 0 ? x ? 0.75 was prepared in aqueous medium in the presence of different concentrations of poly-L-aspartic acid (PASP). XRD, IR, TG-DTA, TEM-EDX, AFM and chemical analyses were used to characterize the structure, morphology and composition of the products. All techniques show the formation of new hybrid compounds Ca-CuHAp-PASP. The presence of the grafting moiety on the apatitic material is more significant with increasing of copper amount and/or organic concentration in the starting solution. These increases lead to the affectation of apatite crystallinity. The IR spectroscopy shows the conservation of (Psbnd OH) band of (HPO4)2- groups, suggesting that PASP acid was interacted only with metallic cations of hydroxyapatite.

Othmani, Masseoud; Aissa, Abdallah; Bachoua, Hassen; Debbabi, Mongi

2013-01-01

17

Local ammonia storage and ammonia inhibition in a monolithic copper-beta zeolite SCR catalyst  

SciTech Connect

Selective catalytic reduction of NO with NH{sub 3} was studied on a Cu-beta zeolite catalyst, with specific focus on the distributed NH{sub 3} capacity utilization and inhibition. In addition, several other relevant catalyst parameter distributions were quantified including the SCR zone, or catalyst region where SCR occurs, and NO and NH{sub 3} oxidation. We show that the full NH{sub 3} capacity (100% coverage) is used within the SCR zone for a range of temperatures. By corollary, unused NH{sub 3} capacity exists downstream of the SCR zone. Consequently, the unused capacity relative to the total capacity is indicative of the portion of the catalyst unused for SCR. Dynamic NH{sub 3} inhibition distributions, which create local transient conversion inflections, are measured. Dynamic inhibition is observed where the gas phase NH{sub 3} and NO concentrations are high, driving rapid NH{sub 3} coverage buildup and SCR. Accordingly, we observe dynamic inhibition at low temperatures and in hydrothermally aged states, but predict its existence very near the catalyst front in higher conversion conditions where we did not specifically monitor its impact. While this paper addresses some general distributed SCR performance parameters including Oxidation and SCR zone, our major new contributions are associated with the NH{sub 3} capacity saturation within the SCR zone and dynamic inhibition distributions and the associated observations. These new insights are relevant to developing accurate models, designs and control strategies for automotive SCR catalyst applications.

Auvray, Xavier P [Chalmers University of Technology, Sweden; Partridge Jr, William P [ORNL; Choi, Jae-Soon [ORNL; Pihl, Josh A [ORNL; Yezerets, Alex [Cummins, Inc; Kamasamudram, Krishna [Cummins, Inc; Currier, Neal [Cummins, Inc; Olsson, Louise [Chalmers University of Technology, Sweden

2012-01-01

18

Surface modification of an epoxy resin with polyamines and polydopamine: The effect on the initial electroless copper deposition  

NASA Astrophysics Data System (ADS)

This paper describes the influence of polydopamine and polyamine surface modifications of an etched epoxy cresol novolak (ECN) resin on the initial electroless copper deposition. Three different strategies to introduce polyamines on a surface in aqueous environment are applied: via polyethyleneimine adsorption (PEI), via polydopamine and via polyamines grafted to polydopamine. Next, the influence of these surface modifications on the catalytic palladium activation is investigated through X-ray photoelectron spectroscopy (XPS) analysis. Finally, the initial electroless copper deposition on modified epoxy surfaces is evaluated using SEM and Energy Dispersive Spectroscopy (EDS). Grafted polyamines on polydopamine surface modifications result in a large increase of the initial deposited copper.

Schaubroeck, David; Mader, Lothar; De Geyter, Nathalie; Morent, Rino; Dubruel, Peter; Vanfleteren, Jan

2014-06-01

19

Removal of sulfonamide antibiotics from water: Evidence of adsorption into an organophilic zeolite Y by its structural modifications  

Microsoft Academic Search

Sulfonamide antibiotics are persistent pollutants of aquatic bodies, known to induce high levels of bacterial resistance. We investigated the adsorption of sulfadiazine, sulfamethazine, and sulfachloropyridazine sulfonamides into a highly dealuminated faujasite zeolite (Y) with cage window sizes comparable to sulfonamide dimensions. At maximal solubility the antibiotics were almost completely (>90%) and quickly (t<1min) removed from the water by zeolite. The

Ilaria Braschi; Sonia Blasioli; Lara Gigli; Carlo E. Gessa; Alberto Alberti; Annalisa Martucci

2010-01-01

20

Surface modification of titanium using nanothin films of copper for biofouling control.  

PubMed

Biofouling is one of the major impediment in the use of titanium, which is otherwise excellent material with respect to corrosion resistance and mechanical properties, for seawater-cooled condensers of power plants. The routine chlorination treatment and sponge ball cleaning may not be successful to keep the titanium condenser tube clean over a period extending to years. This brings into focus the relevance of surface modification of titanium to improve the antimicrobial properties, which can effectively supplement the present treatment programmes. In this study antimicrobial thin film of copper (Cu) is developed on titanium surfaces, as copper is known to be very toxic to microorganisms and effectively kills most of the microbes by blocking the respiratory enzyme system. The preparation of nanocrystalline thin films of copper on titanium surfaces was done by pulsed DC magnetron-sputtering technique. Then this thin film was characterized using Glancing Incidence X-ray Diffraction (GIXRD) and Atomic Force Microscopy (AFM). Antimicrobial properties of these specimens were evaluated by exposure studies in seawater. Results showed two order decrease in the bacterial density on copper coated surface and epifluorescence micrographs depicted very few fluorescing cells and no biofilm formation clearly demonstrating the superior antibacterial capability of this nanocrystalline copper thin film. PMID:19928248

Vishwakarma, Vinita; Manoharan, N; George, R P; Dash, S; Kamruddin, M; Tyagi, A K; Daya, R K

2009-09-01

21

Zeolite A functionalized with copper nanoparticles and graphene oxide for simultaneous electrochemical determination of dopamine and ascorbic acid.  

PubMed

A novel Cu-zeolite A/graphene modified glassy carbon electrode for the simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA) has been described. The Cu-zeolite A/graphene composites were prepared using Cu(2+) functionalized zeolite A and graphene oxide as the precursor, and subsequently reduced by chemical agents. The composites were characterized by X-ray diffraction, Fourier transform infrared spectra and scanning electron microscopy. Based on the Cu-zeolite A/graphene-modified electrode, the potential difference between the oxidation peaks of DA and AA was over 200mV, which was adequate for the simultaneous electrochemical determination of DA and AA. Also the proposed Cu-zeolite/graphene-modified electrode showed higher electrocatalytic performance than zeolite/graphene electrode or graphene-modified electrode. The electrocatalytic oxidation currents of DA and AA were linearly related to the corresponding concentration in the range of 1.0×10(-7)-1.9×10(-5)M for DA and 2.0×10(-5)-2.0×10(-4)M for AA. Detection limits (S/N=3) were estimated to be 4.1×10(-8)M for DA and 1.1×10(-5)M for AA, respectively. PMID:22819046

He, Ping; Wang, Wei; Du, Licheng; Dong, Faqin; Deng, Yuequan; Zhang, Tinghong

2012-08-20

22

Position-dependent performance of copper phthalocyanine based field-effect transistors by gold nanoparticles modification.  

PubMed

A facile fabrication and characteristics of copper phthalocyanine (CuPc)-based organic field-effect transistor (OFET) using the gold nanoparticles (Au NPs) modification is reported, thereby achieving highly improved performance. The effect of Au NPs located at three different positions, that is, at the SiO2/CuPc interface (device B), embedding in the middle of CuPc layer (device C), and on the top of CuPc layer (device D), is investigated, and the results show that device D has the best performance. Compared with the device without Au NPs (reference device A), device D displays an improvement of field-effect mobility (?sat) from 1.65 × 10(-3) to 5.51 × 10(-3) cm(2) V(-1) s(-1), and threshold voltage decreases from -23.24 to -16.12 V. Therefore, a strategy for the performance improvement of the CuPc-based OFET with large field-effect mobility and saturation drain current is developed, on the basis of the concept of nanoscale Au modification. The model of an additional electron transport channel formation by FET operation at the Au NPs/CuPc interface is therefore proposed to explain the observed performance improvement. Optimum CuPc thickness is confirmed to be about 50 nm in the present study. The device-to-device uniformity and time stability are discussed for future application. PMID:25548878

Luo, Xiao; Li, Yao; Lv, Wenli; Zhao, Feiyu; Sun, Lei; Peng, Yingquan; Wen, Zhanwei; Zhong, Junkang; Zhang, Jianping

2015-01-21

23

Position-dependent performance of copper phthalocyanine based field-effect transistors by gold nanoparticles modification  

NASA Astrophysics Data System (ADS)

A facile fabrication and characteristics of copper phthalocyanine (CuPc)-based organic field-effect transistor (OFET) using the gold nanoparticles (Au NPs) modification is reported, thereby achieving highly improved performance. The effect of Au NPs located at three different positions, that is, at the SiO2/CuPc interface (device B), embedding in the middle of CuPc layer (device C), and on the top of CuPc layer (device D), is investigated, and the results show that device D has the best performance. Compared with the device without Au NPs (reference device A), device D displays an improvement of field-effect mobility (?sat) from 1.65 × 10?3 to 5.51 × 10?3 cm2 V?1 s?1, and threshold voltage decreases from ?23.24 to ?16.12 V. Therefore, a strategy for the performance improvement of the CuPc-based OFET with large field-effect mobility and saturation drain current is developed, on the basis of the concept of nanoscale Au modification. The model of an additional electron transport channel formation by FET operation at the Au NPs/CuPc interface is therefore proposed to explain the observed performance improvement. Optimum CuPc thickness is confirmed to be about 50 nm in the present study. The device-to-device uniformity and time stability are discussed for future application.

Luo, Xiao; Li, Yao; Lv, Wenli; Zhao, Feiyu; Sun, Lei; Peng, Yingquan; Wen, Zhanwei; Zhong, Junkang; Zhang, Jianping

2015-01-01

24

Microscopic single particle characterization of zeolites synthesized in a soil polluted by copper or cadmium and treated with coal fly ash  

Microsoft Academic Search

In the perspective of the development of new soil remediation technologies, zeolites can be directly synthesized in soil from fused coal fly ash to reduce heavy metal mobility and availability. Such a process promotes the formation of metal hydroxide\\/oxide precipitates which can be also occluded inside the structure of the forming minerals. In this study, different types of zeolites (zeolite

R. Terzano; M. Spagnuolo; L. Medici; K. Janssens; P. Ruggiero

2007-01-01

25

Luminescent materials derived from the surface-modification of Ln3+-doped zeolite L with a silylated terpyridine  

NASA Astrophysics Data System (ADS)

Herein we report luminescent materials of Ln3+ (Ln = Eu or Tb) doped disc shaped zeolite L crystals (Eu3+/ZLD, Tb3+/ZLD) modified with a silylated terpyridine (Terpy-Si). The modified crystals show bright red emission and green emission under UV-light irradiation due to the energy transfer from the Terpy-Si to the Eu3+ and Tb3+ ions. The obtained materials were characterized with FT-IR, SEM, XRD and elemental analysis. Luminescence spectroscopy was used to study the luminescence properties of the modified Eu3+(Tb3+)/ZLD crystals. The formation of europium(III) and terbium(III) Terpy-Si silicon complexes and energy transfer from Terpy-Si to Eu3+ ions and Tb3+ have been confirmed by luminescence spectroscopy.

Qin, Zhiqiao; Li, Hongshi; Wang, Yige

2014-11-01

26

Ginkgo Biloba Extract (EGb 761) Protects Human Low-Density Lipoproteins against Oxidative Modification Mediated by Copper  

Microsoft Academic Search

The antioxidant effects of Ginkgo biloba extract (EGb 761) on copper-mediated human low density lipoprotein (LDL) oxidative modification were evaluated by several techniques. Human LDL (0.5 mg\\/ml) in phosphate buffered saline, pH 7.4, was incubated with 10 ?M cupric sulfate at 37°C under air for 8 hours and 24 hours in the presence of varying concentrations of EGb 761. Increases

L. J. Yan; M. T. Droylefaix; L. Packer

1995-01-01

27

Copper  

MedlinePLUS

... minimum recommended dietary allowance (RDA) for copper is 0.9 milligrams per day for most adults, 1 ... in the cancer process is still unclear, copper complexes have been shown to ... evidence that trace metals, including copper, iron and zinc, may have a ...

28

Copper.  

PubMed

Copper is an essential trace element, which is an important catalyst for heme synthesis and iron absorption. Following zinc and iron, copper is the third most abundant trace element in the body. Copper is a noble metal, like silver and gold. Useful industrial properties include high thermal and electrical conductivity, low corrosion, alloying ability, and malleability. Most of the metallic copper appears in electrical applications. Copper is a constituent of intrauterine contraceptive devices and the release of copper is necessary for their contraceptive effects. The average daily intake of copper in the US is about 1 mg Cu with the primary source being the diet. The bioavailability of copper from the diet is about 65-70% depending on a variety of factors including chemical form, interaction with other metals, and dietary components. The biological half-life of copper from the diet is 13-33 days with bilary excretion being the major route of elimination. Copper sulfate is a gastric irritant that produces erosion of the lining of the gastrointestinal tract. Chronic copper toxicity is rare and primarily affects the liver. Wilson's disease and Indian childhood cirrhosis are examples of severe chronic liver disease that results from the genetic predisposition to the hepatic accumulation of copper. The serum copper concentration ranges up to approximately 1.5 mg/L in healthy persons. Gastrointestinal symptoms occur at whole blood concentrations near 3 mg Cu/L. Chelating agents (CaNa2EDTA, BAL) are recommended in severe poisoning, but there are little pharmacokinetic data to evaluate the effectiveness of these agents. PMID:10382557

Barceloux, D G

1999-01-01

29

Copper on-top-sputtering induced modification of tin dioxide thin film gas sensors  

Microsoft Academic Search

Thin film gas sensors based on pure tin dioxide were modified by sputtering of copper on the surface of the films. A gradual increase of an amount of the on-top-Cu produced increasing doping with uniform distribution of copper throughout entire tin oxide film. An increase of an amount of Cu caused continuous variation of the clean air resistance and the

A Galdikas; A Mironas; A Šetkus; W Göpel; K.-D Schierbaum

1999-01-01

30

The antibrowning agent sulfite inactivates Agaricus bisporus tyrosinase through covalent modification of the copper-B site.  

PubMed

Sulfite salts are widely used as antibrowning agents in food processing. Nevertheless, the exact mechanism by which sulfite prevents enzymatic browning has remained unknown. Here, we show that sodium hydrogen sulfite (NaHSO3) irreversibly blocks the active site of tyrosinase from the edible mushroom Agaricus bisporus, and that the competitive inhibitors tropolone and kojic acid protect the enzyme from NaHSO3 inactivation. LC-MS analysis of pepsin digests of NaHSO3 -treated tyrosinase revealed two peptides showing a neutral loss corresponding to the mass of SO3 upon MS(2) fragmentation. These peptides were found to be homologous peptides containing two of the three histidine residues that form the copper-B-binding site of mushroom tyrosinase isoform PPO3 and mushroom tyrosinase isoform PPO4, which were both present in the tyrosinase preparation used. Peptides showing this neutral loss behavior were not found in the untreated control. Comparison of the effects of NaHSO3 on apo-tyrosinase and holo-tyrosinase indicated that inactivation is facilitated by the active site copper ions. These data provide compelling evidence that inactivation of mushroom tyrosinase by NaHSO3 occurs through covalent modification of a single amino-acid residue, probably via addition of HSO3(-) to one of the copper-coordinating histidines in the copper-B site of the enzyme. PMID:24112416

Kuijpers, Tomas F M; Gruppen, Harry; Sforza, Stefano; van Berkel, Willem J H; Vincken, Jean-Paul

2013-12-01

31

Improvement of thermal and mechanical properties of graphite/copper composites through interfacial modification  

SciTech Connect

Unidirectionally reinforced graphite/copper composites have been fabricated using a pressure infiltration casting procedure. T300 and T650 graphite fibers have been used to reinforce copper and copper-chromium alloys. The effects of the chromium level in the copper matrix on the tensile strength, stiffness, and thermal expansion behavior of the composites have been evaluated through tensile and three-point bend testing, and thermal cycling. At the 0.5 wt% alloying level, chromium increases the stiffness and optimizes the thermal expansion behavior of graphite/copper composites. The longitudinal tensile strengths of these composites are above 1,606 MPa, whereas the transverse tensile strengths are lower than 40 MPa due to incomplete infiltration during processing. Scanning electron microscopy analyses reveal that the unalloyed copper matrix composites experienced extensive fiber/matrix debonding under tensile loading. The addition of chromium to the copper increases the level of matrix bonding to the graphites fibers, as evidenced by observations of fractured tensile specimens. Auger electron spectroscopy analyses indicate that a chromium carbide phase present at the interface is responsible for the improved bonding.

DeVincent, S.M.; Michal, G.M. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering)

1993-06-01

32

Improvement of thermal and mechanical properties of graphite/copper composites through interfacial modification  

NASA Astrophysics Data System (ADS)

Unidirectionally reinforced graphite/copper composites have been fabricated using a pressure infiltration casting procedure. T300 and T650 graphite fibers have been used to reinforce copper and copperchromium alloys. The effects of the chromium level in the copper matrix on the tensile strength, stiffness, and thermal expansion behavior of the composites have been evaluated through tensile and three-point bend testing, and thermal cycling. At the 0.5 wt% alloying level, chromium increases the stiffness and optimizes the thermal expansion behavior of graphite/copper composites. The longitudinal tensile strengths of these composites are above 1606 MPa, whereas the transverse tensile strengths are lower than 40 MPa due to incomplete infiltration during processing. Scanning electron microscopy analyses reveal that the unalloyed copper matrix composites experienced extensive fiber/matrix debonding under tensile loading. The addition of chromium to the copper increases the level of matrix bonding to the graphite fibers, as evidenced by observations of fractured tensile specimens. Auger electron spectroscopy analyses indicate that a chromium carbide phase present at the interface is responsible for the improved bonding.

Devincent, S. M.; Michal, G. M.

1993-06-01

33

Design and modification of zeolite capsule catalyst, a confined reaction field, and its application in one-step isoparaffin synthesis from syngas  

SciTech Connect

Four kinds of zeolite capsule catalyst with different crystallization conditions were prepared and utilized for the middle isoparaffin direct synthesis via Fischer-Tropsch synthesis (FTS) reaction. Characterization results exhibited that these capsule catalysts had a compact, integral H-ZSM-5 shell. In FTS reactions on these zeolite capsule catalysts, hydrocarbons of C11+ were totally suppressed, accompanied by a sharp anti-Anderson-Schultz-Flory (ASF) law product distribution. The selectivity of light isoparaffin was improved obviously, but with the increase of the olefin's selectivity. Two-stage isoparaffin synthesis reaction, using the combination of zeolite capsule catalyst with hydrogenation catalyst of Pd/SiO{sub 2} in a single reactor as dual-bed catalyst, was also conducted for converting the residual olefins produced by the single zeolite capsule catalyst. Dependent on the palladium role of hydrogenation and hydrogen spillover, almost all the olefins effused from the first stage of zeolite capsule catalyst were hydrogenated, mostly converted to isoparaffin. The selectivity of isoparaffin in the final products was increased markedly as expected. 10 refs., 7 figs., 2 tabs.

Guohui Yang; Jingjiang He; Yi Zhang; Yoshiharu Yoneyama; Yisheng Tan; Yizhuo Han; Tharapong Vitidsant; Noritatsu Tsubaki [University of Toyama, Toyama (Japan). Department of Applied Chemistry

2008-05-15

34

Modification of active carbon and zeolite as ammonia separation materials for a new de-NO x process with ammonia on-site synthesis  

Microsoft Academic Search

Ammonia adsorption and desorption behavior of surface treated active carbon (AC) and ion-exchanged Y zeolite, as ammonia separation and storage materials for a new de-NOx process with ammonia on-site synthesis, were studied. Surface oxidized AC adsorbed more ammonia than non-treated AC due to ammonium ion formation. These materials were found to increase weak adsorption of ammonia and to be useful

Chun Yi Liu; Ken-Ichi Aika

2002-01-01

35

Epitaxial growth of a metastable modification of copper with body-centered-cubic structure  

NASA Astrophysics Data System (ADS)

Slow deposition of Cu onto a clean unheated Fe\\{001\\} surface produced films with large amounts of defects, but still detectable crystallinity. Low-energy electron diffraction showed that the films contained regions with a (somewhat distorted) body-centered-cubic structure and the same or nearly the same lattice parameter as the underlying substrate. Auger-electron spectroscopy suggested that the crystalline regions were essentially pure Cu, thus allowing the conclusion that a metastable bcc modification of Cu has been realized, consistent with the predictions of total-energy band calculations reported elsewhere.

Wang, Z. Q.; Lu, S. H.; Li, Y. S.; Jona, F.; Marcus, P. M.

1987-06-01

36

Relative importance of calcium and magnesium in hardness-based modification of copper toxicity  

SciTech Connect

Because of the relationship between water hardness and the toxicity of many metals, total hardness is used as a model parameter to calculate ambient water quality criteria for copper and other metals. However, the relative contribution of the Ca and Mg components of total hardness as modifiers of metals toxicity is not considered in the water quality criteria. Acute Cu toxicity was measured in rainbow trout (Oncorhynchus mykiss) and chinook salmon (O. tshawytscha) swim-up fry in laboratory waters that were formulated to have similar total hardness and alkalinity but different Ca and Mg concentrations. Experiments were performed at nominal total hardness values of 40 and 90 mg/L (as CaCO{sub 3}). In four paired toxicity tests, acute Cu toxicity was significantly lower, i.e., 96-h LC50s were higher, in laboratory waters containing proportionately more Ca (Ca:Mg molar ratios of 1.5--5.2) than in waters containing less Ca (Ca:Mg molar ratios of 0.2--0.8). the relative increase in the 96-h Cu LC50 at higher Ca concentrations, but similar total hardness concentrations, was between 29 and 86% when the low Ca treatment was similar to American Society for Testing and Materials laboratory water. Failure to account for differences in Ca when matching or adjusting for total hardness thus exerts an important influence on the prediction of metal toxicity. These differences must be addressed in water-effect ratio testing in which paired tests with laboratory and site waters are conducted.

Welsh, P.G.; Lipton, J.; Chapman, G.A.; Podrabsky, T.L.

2000-06-01

37

The Local Environment of Cu+ in Cu-Y Zeolite and Its Relationship to the Synthesis of Dimethyl Carbonate  

E-print Network

The Local Environment of Cu+ in Cu-Y Zeolite and Its Relationship to the Synthesis of Dimethyl, 2005 Cu-exchanged Y zeolite was investigated in order to determine the location of the copper cations relative to the zeolite framework and to determine which Cu cations are active for the oxidative

Bell, Alexis T.

38

Database of Zeolite Structures  

NSDL National Science Digital Library

The Database of Zeolite Structures is provided by the Structure Commission of the International Zeolite Association. Links include an Atlas of Zeolite Framework Types, Collection of Simulated XRD Powder Patterns for Zeolites, Catalog of Disordered Zeolite Structures, Schemes for Building Zeolite Framework Models, and Zeolite Structure References, as well as various publications. The database can be searched or browsed, and contains several useful tools such as the "input your data" link, which allows the user to enter crystallographic data not available in the database and generate the diffraction pattern.

39

Preparation of a Versatile Bifunctional Zeolite for Targeted Imaging Applications  

PubMed Central

Bifunctional zeolite Y was prepared for use in targeted in vivo molecular imaging applications. The strategy involved functionalization of the external surface of zeolite Y with chloropropyltriethoxysilane followed by reaction with sodium azide to form azide-functionalized NaY, which is amenable to copper(1) catalyzed click chemistry. In this study, a model alkyne (4-pentyn-1-ol) was attached to the azide-terminated surface via click chemistry to demonstrate feasibility for attachment of molecular targeting vectors (e.g., peptides, aptamers) to the zeolite surface. The modified particle efficiently incorporates the imaging radioisotope gallium-68 (68Ga) into the pores of the azide-functionalized NaY zeolite to form a stable bifunctional molecular targeting vector. The result is a versatile “clickable” zeolite platform that can be tailored for future in vivo molecular targeting and imaging modalities. PMID:21306141

Ndiege, Nicholas; Raidoo, Renugan; Schultz, Michael K.; Larsen, Sarah

2011-01-01

40

Metal Oxide/Zeolite Combination Absorbs H2S  

NASA Technical Reports Server (NTRS)

Mixed copper and molybdenum oxides supported in pores of zeolite found to remove H2S from mixture of gases rich in hydrogen and steam, at temperatures from 256 to 538 degree C. Absorber of H2S needed to clean up gas streams from fuel processors that incorporate high-temperature steam reformers or hydrodesulfurizing units. Zeolites chosen as supporting materials because of their high porosity, rigidity, alumina content, and variety of both composition and form.

Voecks, Gerald E.; Sharma, Pramod K.

1989-01-01

41

Zeolite catalysis: technology  

SciTech Connect

Zeolites have been used as catalysts in industry since the early nineteen sixties. The great majority of commercial applications employ one of three zeolite types: zeolite Y; Mordenite; ZSM-5. By far the largest use of zeolites is in catalytic cracking, and to a lesser extent in hydrocracking. This paper reviews the rapid development of zeolite catalysis and its application in industries such as: the production of gasoline by catalytic cracking of petroleum; isomerization of C/sub 5/ and C/sub 6/ paraffin hydrocarbons; alkylation of aromatics with olefins; xylene isomerization; and conversion of methanol to gasoline.

Heinemann, H.

1980-07-01

42

Synthetic zeolites as amendments for sewage sludge-based compost.  

PubMed

The effects of incorporating a synthetic zeolite (Zeolite P) in a range of concentrations (0.1-1.0 w:w) into an experimental horticultural compost, derived from sewage sludge, have been investigated. The impact of zeolite treatment on time-related changes of the labile zinc, copper, iron and manganese pools within the compost was compared to lime incorporation (5% w:w) and to a proprietary unamended peat-based compost. Addition of 0.5% and 1.0% zeolite significantly reduced labile zinc over a 90 day period. The highest zeolite treatment was more effective than liming; 0.5% zeolite was as effective as lime. Plant growth trials measuring transfer of metals to ryegrass (Lolium perenne L. cv Elka) in successive harvests demonstrated that both 1.0% zeolite and 5% lime treatment caused significant reduction in total metal transfer from soil-plant over a 116 day growth period. It is concluded that the use of synthetic zeolite as an amendment for compost of this type significantly reduces potential for soil metal mobility and soil-plant transfer. PMID:10819210

Nissen, L R; Lepp, N W; Edwards, R

2000-07-01

43

Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: the influence of zeolite chemical surface characteristics.  

PubMed

In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity. PMID:24794812

Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A

2014-06-15

44

Chromatographic properties of zeolites modified for analysis of atmospheric pollutants  

Microsoft Academic Search

Chromatographic properties of different types of synthetic zeolites and samples of natural mordenite, modified by ion-exchange have been studied. The influence of degree of replacement and character of cations of alkali and alkaline-earth metals and also of silver and copper on chromatographic retainment of constant components of air and its most spread pollutants have been shown. Recommendations are made of

T. G. Andronikashvili; O. S. Banakh; V. I. Rogovik

1989-01-01

45

Interaction of Dimethylmethylphosphonate with Zeolite Y: Impedance-Based Sensor for Detecting Nerve Agent Simulants  

E-print Network

-exchanged zeolites as well as external surface modification with ceria to deactivate acidic groups. A mechanism air. Introduction Zeolites are crystalline aluminosilicates with pores and channels of molecular), surface acoustic wave arrays (e.g., M90), and gas chromatography-mass spectrometry devices (e.g., Hapsite

Dutta, Prabir K.

46

Ammoniacal nitrogen removal from water by treatment with clays and zeolites  

Microsoft Academic Search

The objective of the present study was to investigate the removal of nitrogen in the form of ammonium ions (N-NH+4) from aqueous solutions using natural clay and zeolite. The Croatian zeolite clinoptilolite from the area of Donje Jesenje and Croatian bentonite clay from the Kutina area were used as natural filtration materials. Alkaline and acid modification of natural clay was

M. Roži?; Š Cerjan-Stefanovi?; S. Kurajica; V. Van?ina; E. Hodži?

2000-01-01

47

Multifunctional NO-delivery vessel derived from aminopropyl-modified mesoporous zeolites.  

PubMed

A new strategy, releasing nitric oxide (NO) and adsorbing nitrosamines simultaneously by zeolitic materials in the digestive system, is validated in this paper. Three types of moisture-saturated molecular sieves, HZSM-5 zeolite, mesoporous zeolite, and mesoporous silica MCM-41, are used as NO-delivery vessels in mimic gastric juice after modification of ?-aminopropyltriethoxysilane (APTES). APTES modification dramatically increased the capability of zeolite and mesoporous silica in NO release in acidic solution, because more NO can be adsorbed in the composite and stored in the form of nitrite. Some composites released the NO 10 times more than their parent materials, and synchronously captured the carcinogen nitrosamines in mimic gastric juice. The influences of APTES modification on the porous structure and surface state of zeolite and mesoporous silica were investigated by XRD, N(2) adsorption, and FTIR tests, through which the mesoporous zeolite is proven to be the optimal support. With this hierarchical material a controllable APTES modification is realized in which a lot of aminopropyl groups are grafted in mesopores while the zeolitic structure is maintained, so the resulting sample exhibits a high capability in releasing NO and adsorbing nitrosamines. This investigation provides a clue for elevating the efficiency of zeolites in the application of life science. PMID:21306723

Wei, Feng; Hou, Qian; Yang, Jia Yuan; Zhu, Jian Hua

2011-04-15

48

Studies of anions sorption on natural zeolites.  

PubMed

This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. PMID:25002191

Barczyk, K; Mozgawa, W; Król, M

2014-12-10

49

Diagram of Zeolite Crystals  

NASA Technical Reports Server (NTRS)

The Center for Advanced Microgravity Materials Processing (CAMMP) in Cambridge, MA, a NASA-sponsored Commercial Space Center, is working to improve zeolite materials for storing hydrogen fuel. CAMMP is also applying zeolites to detergents, optical cables, gas and vapor detection for environmental monitoring and control, and chemical production techniques that significantly reduce by-products that are hazardous to the environment. Depicted here is one of the many here complex geometric shapes which make them highly absorbent. Zeolite experiments have also been conducted aboard the International Space Station

2003-01-01

50

Characterization of lead sorption by the natural and Fe(III)-modified zeolite  

NASA Astrophysics Data System (ADS)

The influence of contact time, temperature and particle size on lead sorption by the natural and Fe(III)-modified zeolites was investigated. Characterization of the natural and Fe(III)-modified zeolite before and after lead sorption was performed by determination of textural properties, by scanning electron microscopy and X-ray spectroscopy in energy-dispersive mode (SEM-EDS), transmission electron microscopy (TEM) and X-ray powder diffraction (XRPD) analysis. Lead sorption kinetics at 303-333 K, best represented by the pseudo-second order model and activation energy (13.5 and 8.5 kJ/mol for the natural and Fe(III)-modified zeolite respectively) confirmed an activated chemical sorption. Desorption experiments indicated that lead was irreversibly sorbed on both zeolites. XRPD, TEM and SEM results showed that modification of the natural zeolite with Fe(III) ions did not change its crystal structure and iron is mainly located at the zeolite surface, likely in form of amorphous iron oxy-hydroxides. Specific surface area significantly increases after modification of the natural zeolite with Fe(III) ions (from 30.2 for the natural to 52.5 m2/g for Fe(III)-modified zeolite). Characterization of both lead saturated sorbents suggested that besides ion exchange, lead is both chemisorbed and precipitated at their surfaces, and presence of amorphous iron in Fe(III)-modified zeolite favors sorption of lead.

Kragovi?, Milan; Dakovi?, Aleksandra; Markovi?, Marija; Krsti?, Jugoslav; Gatta, G. Diego; Rotiroti, Nicola

2013-10-01

51

Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol  

NASA Astrophysics Data System (ADS)

Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure of zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N2 adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.

Ayoub, Muhammad; Abdullah, Ahmad Zuhairi; Inayat, Abrar

2014-10-01

52

Composite zeolite membranes  

DOEpatents

A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

Nenoff, Tina M. (Albuquerque, NM); Thoma, Steven G. (Albuquerque, NM); Ashley, Carol S. (Albuquerque, NM); Reed, Scott T. (Albuquerque, NM)

2002-01-01

53

Study of zeolite influence on analytical characteristics of urea biosensor based on ion-selective field-effect transistors  

PubMed Central

A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors. PMID:24636423

2014-01-01

54

Preparation and characterization of TiO 2 incorporated Y-zeolite  

Microsoft Academic Search

A preparation of TiO2-dispersed Y-zeolite has been attempted by a method comprising a substantial ion-exchange of ammonium titanyl oxalate (NH4)2TiO(C2O4)2 and its decomposition. The modification of Y-zeolite was well controlled from the viewpoint of the incorporated amount of TiO2. The framework of Y-zeolite was retained through the modification and TiO2 was incorporated in the form of anatase microcrystals. Titanium species

H. Chen; A. Matsumoto; N. Nishimiya; K. Tsutsumi

1999-01-01

55

Microporous Zeolite MembranesMicroporous Zeolite Membranes and Their Potential for Hand Their Potential for H22 ProductionProduction  

E-print Network

Microporous Zeolite MembranesMicroporous Zeolite Membranes and Their Potential for Hand interest." 22 Zeolites andZeolites and ZeotypesZeotypes ZeoliteZeolite ­­ A crystallineA crystalline zeolites.same structure as known zeolites. MFI Zeolite #12;"...exceptional service in the national interest

56

Zeolite with trimodal porosity by desilication of zeolite nanocrystals aggregate  

SciTech Connect

Zeolite with trimodal porosity can be synthesized by desilication of zeolite nanocrystal aggregate. In the desilication process, the originally existed intercrystalline mesopores of zeolite nanocrystal aggregate were enlarged into large mesopore, and the new small intracrystalline mesopore channel was created, thus the Zeolite with trimodal porosity was formed. The structure of resulted zeolite, both on aggregate and mesopore level can be fine tuned by the desilication degree. - Graphical abstract: The Si from the edges and boundary of nanocrystals was first removed resulted the surface roughness and enlarges of the originally existed intercrystalline mesopores. As the degree of alkali-treatment increasing, the Si species inside zeolite nanocrystals was also removed, leading to further enlarges the intercrystalline mesopores and the formation of small intracrystalline mesopores. In case the alkali-treatment is serve enough to completely dissolve the bridges between zeolite nanocrystals, zeolite nanocrystals were exfoliated from the aggregate. Highlights: Black-Right-Pointing-Pointer Zeolite with trimodal porosity by desilication of zeolite nanocrystals aggregate. Black-Right-Pointing-Pointer The original intercrystalline mesopores were enlarged into large mesopore. Black-Right-Pointing-Pointer The new intracrystalline mesopores were created as the inside Si extracted out. Black-Right-Pointing-Pointer The aggregate structure, crystallinity and acidity of parent zeolite remained. Black-Right-Pointing-Pointer Desilication is start on the edges then in the inner part of zeolite.

Wang Yuxin; Liu Kaituo [Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese academy of Sciences, 189 Songling road, Qingdao 266101 (China) [Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese academy of Sciences, 189 Songling road, Qingdao 266101 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); He Tao; Wu Jinhu [Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese academy of Sciences, 189 Songling road, Qingdao 266101 (China)] [Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese academy of Sciences, 189 Songling road, Qingdao 266101 (China); Fang Yunming, E-mail: fangym@qibebt.ac.cn [Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese academy of Sciences, 189 Songling road, Qingdao 266101 (China)

2012-10-15

57

Preparation of functionalized zeolitic frameworks  

DOEpatents

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Yaghi, Omar M.; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P.

2014-08-19

58

Preparation of functionalized zeolitic frameworks  

DOEpatents

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Yaghi, Omar M; Furukawa, Hiroyasu; Wang, Bo

2013-07-09

59

Preparation of functionalized zeolitic frameworks  

DOEpatents

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Yaghi, Omar M; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P

2012-11-20

60

The influence of zeolite type A on metal concentrations in water and waste water  

Microsoft Academic Search

Investigations were made to determine the removals of calcium, copper, chromium, nickel, lead and zinc from water and waste\\u000a water samples by different concentrations of zeolite type A and with zeolite type A forms where sodium had been partially\\u000a exchanged for calcium. Metal concentrations were determined after a range of different treatments such as filtration, sedimentation\\u000a in columns and centrifugation.

L. A. Obeng; M. J. T. Carrondo; R. Perry; J. N. Lester

1981-01-01

61

The application of natural zeolites for mercury removal: from laboratory tests to industrial scale  

Microsoft Academic Search

The paper discusses the application of natural zeolites from clinoptilolite group for mercury removal from industrial effluents from copper smelter and refinery. The experiments included studies on sorption mechanisms (adsorption or ion-exchange) and sorption equilibria. The dominating mechanism of sorption with zeolite was found to be ion exchange and the maximum sorption capacity was evaluated as 1.21 meq\\/g sorbent. Three

A. Chojnacki; K. Chojnacka; J. Hoffmann; H. Górecki

2004-01-01

62

Adamantanes from petroleum with zeolites  

Microsoft Academic Search

Experiments with zeolite Beta and zeolite Y demonstrate that adamantane and methyl adamantanes can be isolated very effectively from modern refinery streams by mild hydrocracking over Pt-and Pd-containing large pore zeolites. Yield depends importantly on individual refinery crude source and process configuration. Heavy crudes and refineries with conventional hydrocracking and FCC feed hydrotreater facilities are particularly desirable, and an ideal

L. Deane Rollmann; Larry A. Green; Robert A. Bradway; Hye Kyung C. Timken

1996-01-01

63

Advances in nanosized zeolites  

NASA Astrophysics Data System (ADS)

This review highlights recent developments in the synthesis of nanosized zeolites. The strategies available for their preparation (organic-template assisted, organic-template free, and alternative procedures) are discussed. Major breakthroughs achieved by the so-called zeolite crystal engineering and encompass items such as mastering and using the physicochemical properties of the precursor synthesis gel/suspension, optimizing the use of silicon and aluminium precursor sources, the rational use of organic templates and structure-directing inorganic cations, and careful adjustment of synthesis conditions (temperature, pressure, time, heating processes from conventional to microwave and sonication) are addressed. An on-going broad and deep fundamental understanding of the crystallization process, explaining the influence of all variables of this complex set of reactions, underpins an even more rational design of nanosized zeolites with exceptional properties. Finally, the advantages and limitations of these methods are addressed with particular attention to their industrial prospects and utilization in existing and advanced applications.

Mintova, Svetlana; Gilson, Jean-Pierre; Valtchev, Valentin

2013-07-01

64

Separations Using Zeolite Membranes  

Microsoft Academic Search

This overview describes some of the main features of the use of zeolite membranes for separation applications. Four different types of separations are considered: separation of non-adsorbing compounds, of organic molecules, of permanent gases from vapors, and of water (or polar molecules) from organic (or non-polar) species. Several factors, such as the limiting pore size and pore size distribution, surface

Joaquín Coronas; Jesús Santamaría

1999-01-01

65

Diffusion in zeolites  

Microsoft Academic Search

Recent developments in the study of intracrystalline diffusion in zeolites by novel macroscopic methods and the results obtained by some of these methods are reviewed. For many systems there is a significant discrepancy between the macroscopic and microscopic (QENS, PFG NMR) diffusivity values. A possible explanation is suggested.

Douglas M. Ruthven

1995-01-01

66

Theoretical study of vanadium oxides interaction with Y-zeolite.  

PubMed

A current problem about oils and feedstock in fluid catalytic cracking (FCC) is the continuous cumulative deposition of metal contaminants on the catalyst, resulting in important modifications of its properties. Vanadium plays a detrimental role on the catalyst components because enhances the destruction of the Y-zeolite structure during regeneration stage when it is exposed by steam and oxygen at high temperatures. Knowledge of the mechanism interaction of vanadium with the catalyst is important to improve FCC performance. Quantum Molecular Dynamics calculations were done introducing the VO, V2O3, VO2 or V2O5 molecules at the center of a Y-zeolite ring simulating regeneration conditions. The results indicate that the principal reaction is carried out among the zeolite and the vanadium atoms of molecules. This happens, when interaction is presented, since the loss of a hydrogen atom of the active place causes high degree of oxygen reactivity. PMID:19205212

Arroyo, M; Sansores, L E; Salcedo, R; Montoya, J A

2008-12-01

67

Zeolite crystal growth in space  

NASA Technical Reports Server (NTRS)

The growth of large, uniform zeolite crystals in high yield in space can have a major impact on the chemical process industry. Large zeolite crystals will be used to improve basic understanding of adsorption and catalytic mechanisms, and to make zeolite membranes. To grow large zeolites in microgravity, it is necessary to control the nucleation event and fluid motion, and to enhance nutrient transfer. Data is presented that suggests nucleation can be controlled using chemical compounds (e.g., Triethanolamine, for zeolite A), while not adversely effecting growth rate. A three-zone furnace has been designed to perform multiple syntheses concurrently. The operating range of the furnace is 295 K to 473 K. Teflon-lined autoclaves (10 ml liquid volume) have been designed to minimize contamination, reduce wall nucleation, and control mixing of pre-gel solutions on orbit. Zeolite synthesis experiments will be performed on USML-1 in 1992.

Sacco, Albert, Jr.; Thompson, Robert W.; Dixon, Anthony G.

1991-01-01

68

Novel modified zeolites for energy-efficient hydrocarbon separations.  

SciTech Connect

We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their unique pore structures and adsorption properties and their thermal, mechanical and chemical properties. Because of zeolites separation properties, low cost, and robustness in industrial process, they are natural choice for use as industrial adsorbents. This is a multidisciplinary effort to research, design, develop, engineer, and test new and improved materials for the separation of branched vs. linear organic molecules found in commercially important HC streams via adsorption based separations. The focus of this project was the surface and framework modification of the commercially available zeolites, while tuning the adsorption properties and the selectivities of the bulk and membrane separations. In particular, we are interested with our partners at Goodyear Chemical, on how to apply the modified zeolites to feedstock isoprene purification. For the characterization and the property measurements of the new and improved materials powder X-ray diffraction (PXRD), Residual Gas Analyzer-Mass Spectroscopy (RGA-MS), Electron Microscopy (SEM/EDAX), temperature programmed desorption (TPD) and surface area techniques were utilized. In-situ carbonization of MFI zeolite membranes allowed for the maximum separation of isoprene from n-pentane, with a 4.1% enrichment of the binary stream with n-pentane. In four component streams, a modified MFI membrane had high selectivities for n-pentane and 1-3-pentadiene over isoprene but virtually no separation for the 2-methyl-2-butene/isoprene pair.

Arruebo, Manuel (University of Colorado, Boulder, CO); Dong, Junhang; Anderson, Thomas (Burns and McDonnell, Kansas City, MO); Gu, Xuehong; Gray, Gary (Goodyear Chemical Company, Akron, OH); Bennett, Ron (Goodyear Chemical Company, Akron, OH); Nenoff, Tina Maria; Kartin, Mutlu; Johnson, Kaylynn (Goodyear Chemical Company, Akron, OH); Falconer, John (University of Colorado, Boulder, CO); Noble, Richard (University of Colorado, Boulder, CO)

2006-11-01

69

Characterization of zeolite L nanoclusters  

Microsoft Academic Search

Zeolite L (structure code LTL) crystals are synthesized starting from homogeneous potassium aluminosilicate solutions. Particle size and shape of the formed zeolite L are examined by high-resolution transmission electron microscopy, field emission-scanning electron microscopy, X-ray diffraction, and dynamic light scattering. The synthesis conditions reported lead to nanoclusters of aligned zeolite crystalline domains of dimensions â¼40 nm in the channel direction

Michael Tsapatsis; Mark Lovallo; Masayoshi Sadakata; Mark E. Davis

1995-01-01

70

Zeolite exposure and associated pneumoconiosis  

SciTech Connect

Naturally occurring zeolite minerals are aluminum silicates widespread in the earth's crust. Several of these minerals have fibrous forms and have been implicated as a possible cause of benign and malignant diseases of the lung and pleura in Turkey. This report describes a patient, living in an area of Nevada rich in zeolites, who presented with idiopathic pleural thickening and pulmonary fibrosis associated with extensive pulmonary deposition of zeolites.

Casey, K.R.; Shigeoka, J.W.; Rom, W.N.; Moatamed, F.

1985-06-01

71

Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures  

USGS Publications Warehouse

Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ???70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.

1998-01-01

72

Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures  

SciTech Connect

Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. The authors investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by {ge}70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

Besser, J.M.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States); Leonard, E.N.; Mount, D.R. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.

1998-11-01

73

Nanoclusters in Zeolite  

NASA Astrophysics Data System (ADS)

Nanoclusters of Se, Rb-Se, and Cs-Se were incorporated in the supercages of Y zeolite. Anomalous x-ray scattering established that the Se clusters take the form of weakly interacting chains with a disordered structure similar to that of amorphous Se, while the Rb-Se and Cs-Se clusters contain Se2-2 Zintl ions as in crystalline and liquid bulk phases. The Raman spectra of the nanoclusters exhibit features found in the bulk disordered phases.

Armand, Pascale; Saboungi, Marie-Louise; Price, D. L.; Iton, L.; Cramer, Cornelia; Grimsditch, M.

1997-09-01

74

Electroanalytical chemistry with zeolites  

Microsoft Academic Search

In this paper we explore how solution phase molecules affect the electrochemistry of silver-cation exchanged zeolite-modified electrodes (ZMEs). Furthermore, we examine the potential utility of ZME response to quantify solution phase analytes in aqueous and non-aqueous solutions. We give several examples which show that ZMEs are useful in assessing detection efficiencies and analyte selectivities. However, flow systems are better if

C. Senaratne; J. Zhang; J. Fox; I. Burgess; M. D. Baker

1999-01-01

75

Gas phase catalysis by zeolites  

Microsoft Academic Search

This paper provides an overview about today’s use of zeolites and related microporous materials as catalysts within the fields of refining, petrochemistry and commodity chemicals. The content of this presentation is devoted to gas phase catalysis—with focus on acid catalysis, hydrocarbon conversion and formation, oil and natural gas upgrading as well as catalytic probe reactions for the characterisation of zeolites

Michael Stöcker

2005-01-01

76

Zeolite-modified electrodes in electroanalytical chemistry  

Microsoft Academic Search

This review reports on the analytical applications of chemically modified electrodes involving zeolites or zeolite-like materials. After a brief introduction on zeolites, the implication of these solids in electrochemistry is discussed. The interest of zeolite-modified electrodes (ZMEs) for electroanalytical purpose is pointed out, by classifying the applications into five main categories depending on the detection process. In the last decade,

A. Walcarius

1999-01-01

77

Verified Syntheses of Zeolitic Materials  

NSDL National Science Digital Library

From the International Zeolitic Association comes this online version of the special issue of Microporous and Mesoporous Materials, Volume 22, Issues 4-6, featuring a "cookbook" of "recipes" for making zeolites. Zeolites, of which there are over 100 structure types, occur naturally in some cases, but usually are prepared synthetically. Few are available commercially so researchers wanting to test a zeolite in a new application often must attempt the synthesis of the base zeolite in the laboratory. This book is intended to assist in this endeavor, says the editor, Dr. Harry Robson of Louisiana State University. The recipes can be accessed by material name or structure type. A preface, introductory and explanatory notes, and safety information are provided. The recipes include information on source materials, batch preparation and crystallization instructions, product phase, and XRD characterization. The contributor's name, date of entry, and references accompany each recipe.

78

Utilizing copper(I) catalyzed azide-alkyne Huisgen 1,3-dipolar cycloaddition for the surface modification of colloidal particles with electroactive and emissive moieties  

NASA Astrophysics Data System (ADS)

The development of charge-transporting and fluorescing colloidal particles that can be directly printed into electroluminescent devices may result in a broad impact on the use of electrical energy for illumination. The objective of this work was to design and synthesize electroactive & fluorescing colloidal particles; establish their optical, electronic, and thermodynamic properties; and transition them into a device format for potential applications. The original intended application of this work was to build "better" colloidally-based organic light emitting devices (OLEDs) by creating functional particles with superior electrical and optical performance relative to commercially available technologies, but through the course of the research, the particles that were developed were found to be better suited for medical applications. Nonetheless, the global objective envisioned at the onset of this research was consistent with its final outcomes. The research tasks pursued to accomplish this global objective included: (1) The design and synthesis of electroactive moieties and their conversion into organic light emitting devices; An electron-transporting monomer was synthesized that was structurally & energetically similar to the small molecule 2-biphenyl-4-yl-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD). The monomer was copolymerized with 2-(9H-carbazol-9-yl)ethyl 2-methylacrylate (CE) and the resulting copolymer was utilized in OLEDs which employed fluorescent coumarin 6 (C6) or phosphorescent tris(2-phenylpyridine)iridium(III) [Ir(ppy)3] emitters. The copolymer devices exhibited a mean luminance of ca. 400 and 3,552 cd/m2 with the C6 and Ir(ppy)3 emitters, that were stable with thermal aging at temperatures ranging from 23°C to 130°C. Comparable poly(9-vinyl-9H-carbazole)/tBu-PBD blend devices exhibited more pronounced variations in performance with thermal aging. (2) The surface-modification of colloids with electroactive & fluorescing moieties via "click" chemistry; Aqueous-phase 83 nm poly(propargyl acrylate) (PA) nanoparticles were surface-functionalized with sparingly water soluble fluorescent moieties through a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) (i.e., "click" transformation) to produce fluoroprobes with a large Stokes shift. For moieties which could not achieve extensive surface coverage on the particles utilizing a standard click transformation procedure, the presence of beta-cyclodextrin (beta-CD) during the transformation enhanced the grafting density onto the particles. For an oxadiazole containing molecule (AO), an azide-modified coumarin 6 (AD1) and a polyethylene glycol modified naphthalimide-based emitter (AD2), respectively, an 84%, 17% and 5% increase in the grafting densities were observed, when the transformation was performed in the presence of beta-CD. In contrast, a carbazolyl-containing moiety (AC) exhibited a slight retardation in the final grafting density when beta-CD was employed. Photoluminescence studies indicated that AC & AO when attached to the particles form an exciplex. An efficient energy transfer from the exciplex to the surface attached AD2 resulted in a total Stokes shift of 180 nm for the modified particles. (3) The synthesis and characterization of near-infrared (NIR) emitting particles for potential applications in cancer therapy. PA particles were surface modified through the "click" transformation of an azide-terminated indocyanine green (azICG), an NIR emitter, and poly(ethylene glycol) (azPEG) chains of various molecular weights. The placement of azICG onto the surface of the particles allowed for the chromophores to complex with bovine serum albumin (BSA) when dispersed in PBS that resulted in an enhancement of the dye emission. In addition, the inclusion of azPEG with the chromophores onto the particle surface resulted in a synergistic nine-fold enhancement of the fluorescence intensity, with azPEGs of increasing molecular weight amplifying the response. Preliminary photodynamic therapy (PDT)

Rungta, Parul

79

Methanol conversion on acidic ZSM-5, offretite, and mordenite zeolites: a comparative study of the formation and stability of coke deposits  

Microsoft Academic Search

The deposition of carbonaceous residues, leading to aging and modifications in the acidic properties of three zeolite samples differing by the size and shape of their interconnecting channel networks (ZSM-5, offretite, and mordenite), has been investigated during the conversion reaction of methanol to hydrocarbons. Catalytic tests, thermogravimetry, and microcalorimetry are used as complementary techniques. For zeolite ZSM-5, it is observed

P. Dejaifve; A. Auroux; P. C. Gravelle; J. C. Vedrine; Z. Gabelica; E. G. Derouane

1981-01-01

80

Oxygen and hydrogen isotope geochemistry of zeolites  

NASA Technical Reports Server (NTRS)

Oxygen and hydrogen isotope ratios for natural samples of the zeolites analcime, chabazite, clinoptilolite, laumontite, mordenite, and natrolite have been obtained. The zeolite samples were classified into sedimentary, hydrothermal, and igneous groups. The ratios for each species of zeolite are reported. The results are used to discuss the origin of channel water, the role of zeolites in water-rock interaction, and the possibility that a calibrated zeolite could be used as a low-temperature geothermometer.

Karlsson, Haraldur R.; Clayton, Robert N.

1990-01-01

81

The synthesis of zeolites from fly ash and the properties of the zeolite products  

Microsoft Academic Search

Fly ash produced during the combustion of powdered coal could be converted up to 45% into zeolite. By varying the experimental conditions different types of zeolite were produced, e.g. zeolite Na-P1, zeolite K-G and zeolite ZK19. By this zeolitization process the cation exchange capacity (CEC) was raised from 0.02 to circa 2.4 meq\\/g. Anionic heavy metals were largely extracted by

G Steenbruggen; G. G Hollman

1998-01-01

82

Enantioselective dehydration of butan-2-ol using zeolite Y modified with dithiane oxides  

SciTech Connect

Modification of zeolite H-Y by dithiane oxides (2-R-1,3-dithiane 1-oxide; R = H, CH{sub 3}, C{sub 6}H{sub 5}) is shown to enhance significantly its activity for the acid catalyzed gas phase dehydration of butan-2-ol. The rate enhancement is observed for catalysts that are prepared by adding the dithiane oxide to the zeolite synthesis gel or by adsorption of the dithiane oxide onto commercial samples of zeolite H-Y. The origin of the rate enhancement is considered to result from a specific interaction between the dithiane oxide modifier with both the extra-framework and framework aluminum in the zeolite. Modification of zeolite H-Y with (R)-1,3-dithiane 1-oxide enhances the conversion of (S)-butan-2-ol compared to (R)-butan-2-ol in the temperature range 110-150{degrees}C when the two enantiomers are reacted separately. Modification with (S)-2-phenyl-1,3-dithiane 1-oxide gives a catalyst for which (R)-butan-2-ol is the most reactive of the two enantiomers. Reaction of racemic butan-2-ol over these chirally modified H-Y zeolites demonstrates that this modification procedure makes the zeolite enantiomerically discriminating and one enantiomer preferentially reacts, although both are present in the micropores under the reaction conditions. This effect is considered to be due to enantioselective rate enhancement, since, although the rate of dehydration of both enantiomers is enhanced in the chiral environment, the dehydration rate of one enantiomer is accelerated relative to the other. It is suggested that the effect is due to preferential adsorption at the chiral active site. 34 refs., 7 figs., 6 tabs.

Feast, S.; Siddiqui, H.; Bethell, D. [Univ. of Liverpool (United Kingdom)] [and others] [Univ. of Liverpool (United Kingdom); and others

1997-04-15

83

Study of ethylene adsorption on zeolite NaY modified with group I metal ions  

NASA Astrophysics Data System (ADS)

The adsorption of ethylene by zeolite NaY and zeolite NaY modified by cation exchange with potassium, rubidium, and cesium ions was studied. Cation exchanges were carried out using KNO 3, RbNO 3, and CsNO 3 in the concentration ranges of 0.2-10 mM. XRD patterns and specific surface areas illustrated that modification of NaY zeolite by very dilute solutions containing K +, Rb + and Cs + did not lead to significant changes in the crystallinity. Analysis of metals content (ICP-OES) showed that Cs + can replace Na + better than Rb + and K +. Particle analysis indicated slight decreases in surface area but pore volumes and pore diameters remained unchanged. Ethylene adsorption isotherms indicated that Na-Y zeolite which was modified by 5.0 mM KNO 3, 0.5 mM RbNO 3 and 1.0 mM CsNO 3 could adsorb ethylene better than zeolite Na-Y. K-NaY zeolite adsorbed up to 102.45 cm 3/g ethylene, while Rb-NaY and Cs-NaY zeolites adsorbed up to 98.50 cm 3/g and 90.15 cm 3/g ethylene, respectively. Ethylene adsorption capacities depended on number of adsorption sites and surface interactions.

Sue-aok, Niramai; Srithanratana, Tipaporn; Rangsriwatananon, Kunwadee; Hengrasmee, Sunantha

2010-04-01

84

Properties and applications of zeolites.  

PubMed

Zeolites are aluminosilicate solids bearing a negatively charged honeycomb framework of micropores into which molecules may be adsorbed for environmental decontamination, and to catalyse chemical reactions. They are central to green-chemistry since the necessity for organic solvents is minimised. Proton-exchanged (H) zeolites are extensively employed in the petrochemical industry for cracking crude oil fractions into fuels and chemical feedstocks for other industrial processes. Due to their ability to perform cation-exchange, in which the cations that are originally present to counterbalance the framework negative charge may be exchanged out of the zeolite by cations present in aqueous solution, zeolites are useful as industrial water-softeners, in the removal of radioactive Cs+ and Sr2+ cations from liquid nuclear waste and in the removal of toxic heavy metal cations from groundwaters and run-off waters. Surfactant-modified zeolites (SMZ) find particular application in the co-removal of both toxic anions and organic pollutants. Toxic anions such as arsenite, arsenate, chromate, cyanide and radioactive iodide can also be removed by adsorption into zeolites that have been previously loaded with co-precipitating metal cations such as Ag+ and Pb2+ which form practically insoluble complexes that are contained within the zeolite matrix. PMID:21047018

Rhodes, Christopher J

2010-01-01

85

Ligand exchange photochemistry of iodopentaamminerhodium (III) in a sodium/hydrogen Y type zeolite  

E-print Network

L) and the second solution was an aqueous mixture of copper sulfate pentahydrate (0. 44 g) and concentrated ammonium hydroxide (18 mL) diluted to 100 mL. 1 1 ~AA 6 1h y 1 th 1 ghl was determined by using the wet chemical technique titled above. A modified... to determine the effects that the zeolite may have upon a photochemical reaction, iodopentaammine- rhodium (III) perchlorate has been prepared and its subsequent photo- aquation has been studied in solution as well as in the zeolite. A This thesis follows...

Camara, Michael Joseph

2012-06-07

86

Multi-component lanthanide hybrids based on zeolite A/L and zeolite A/L-polymers for tunable luminescence.  

PubMed

Some multi-component hybrids based on zeolite L/A are prepared. Firstly, zeolite A/L is loaded with lanthanide complexes (Eu-DBM or Tb-AA (acetylacetone = AA, dibenzoylmethane = DBM)) into its channels. Secondly, 3-methacryloyloxypropyltrimethoxysilane (?-MPS) is used to covalently graft onto the surface of functionalized zeolite A/L (Si-[ZA/L?Eu-DBM(Tb-AA)]). Thirdly, lanthanide ions (Eu(3+)/Tb(3+)) are coordinated to the functionalized zeolite A/L and ligands (phen(1,10-phenanthroline) or bipy (2,2'-bipyridyl)) are introduced by a ship-in-bottle method. The inside-outside double modifications of ZA/L with lanthanide complexes afford the final hybrids and these are characterized by means of XRD, FT-IR, UV-vis DRS, SEM and luminescence spectroscopy, some of which display white or near-white light emission. Furthermore, selected above-mentioned hybrids are incorporated into PEMA/PMMA (poly ethyl methylacryate/poly methyl methacrylate) hosts to prepare luminescent polymer films. These results provide abundant data that these hybrid materials can be expected to have potential application in various practical fields. PMID:25411917

Chen, Lei; Yan, Bing

2015-02-01

87

Adsorption of unsaturated hydrocarbons on zeolites: the eects of the zeolite framework on adsorption  

E-print Network

Adsorption of unsaturated hydrocarbons on zeolites: the eects of the zeolite framework-FAU) and H-ZSM-5 zeolites have been investigated by both the cluster and embedded cluster approaches with the experimental observation that the ZSM-5 is more acidic than that of FAU zeolite. The adsorption energy

Truong, Thanh N.

88

POLYMER-ZEOLITE NANOCOMPOSITE HIGH-TEMPERATURE  

E-print Network

POLYMER-ZEOLITE NANOCOMPOSITE HIGH-TEMPERATURE PROTON-EXCHANGE-MEMBRANE FOR FUEL CELLS Prepared For://www.energy.ca.gov/research/index.html. #12;Page 1 Polymer-Zeolite Nanocomposite High Temperature Proton-Exchange- Membrane for Fuel Cells EI SMALL GRANT (EISG) PROGRAM INDEPENDENT ASSESSMENT REPORT (IAR) POLYMER-ZEOLITE NANOCOMPOSITE HIGH-TEMPERATURE

89

Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite  

NASA Astrophysics Data System (ADS)

The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this modified zeolite was useful for the dynamic adsorption of polar compound such as methanol. The obtained results were consistent with those reported in other studies related with the use of zeolites in the removal of organic compounds from the liquid phase.

Costa Hernandez, Alba Nydia

90

Parameters influencing zeolite incorporation in PDMS membranes  

SciTech Connect

The incorporation of several types of zeolite in PDMS membranes is studied, by measuring the tensile strength, xylene sorption, and density of the membranes. The zeolite is shown to be involved in the cross-linking of the membrane. The interaction between the PDMS matrix and the zeolites results in reinforced membranes in the case of zeolite Y. The parameters influencing the dispersion of the zeolite in the membrane are investigated, as well as several aspects of the preparation method. Finally, the idea of cross-linking is applied to explain the results of water/ethanol pervaporation. 25 refs., 9 figs., 4 tabs.

Vankelecom, I.F.J.; Scheppers, E.; Heus, R.; Uytterhoeven, J.B. (Katholieke Universiteit Leuven (Belgium))

1994-11-24

91

Zeolites with continuously tuneable porosity.  

PubMed

Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings. PMID:25284344

Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; ?ejka, Ji?í; Morris, Russell E

2014-11-24

92

Zeolite-dye micro lasers  

E-print Network

We present a new class of micro lasers based on nanoporous molecular sieve host-guest systems. Organic dye guest molecules of 1-Ethyl-4-(4-(p-Dimethylaminophenyl)-1,3-butadienyl)-pyridinium Perchlorat were inserted into the 0.73-nm-wide channel pores of a zeolite AlPO$_4$-5 host. The zeolitic micro crystal compounds where hydrothermally synthesized according to a particular host-guest chemical process. The dye molecules are found not only to be aligned along the host channel axis, but to be oriented as well. Single mode laser emission at 687 nm was obtained from a whispering gallery mode oscillating in a 8-$\\mu$m-diameter monolithic micro resonator, in which the field is confined by total internal reflection at the natural hexagonal boundaries inside the zeolitic microcrystals.

Vietze, U; Laeri, F; Ihlein, G; Schüth, F; Limburg, B; Abraham, M

1998-01-01

93

Spectroscopic signatures of nitrogen-substituted zeolites.  

PubMed

Nanoporous acid catalysts such as zeolites form the backbone of catalytic technologies for refining petroleum. With the promise of a biomass economy, new catalyst systems will have to be discovered, making shape-selective base catalysts especially important because of the high oxygen content in biomass-derived feedstocks. Strongly basic zeolites are attractive candidates, but such materials are notoriously difficult to make due to the strong inherent acidity of aluminosilicates. Several research groups have endeavored to produce strongly basic zeolites by treating zeolites with amines, but to date there is no compelling evidence that nitrogen is incorporated into zeolite frameworks. In this communication, we detail synthesis, NMR spectroscopy, and quantum mechanical calculations showing that nitrogen adds onto both surface and interior sites while preserving the framework structure of zeolites. This finding is crucial for the rational design of new biomass-refinement catalysts, allowing 50 years of zeolite science to be brought to bear on the catalytic synthesis of biofuels. PMID:18855470

Hammond, Karl D; Dogan, Fulya; Tompsett, Geoffrey A; Agarwal, Vishal; Conner, W Curtis; Grey, Clare P; Auerbach, Scott M

2008-11-12

94

Structural Characterization of Zeolite Beta  

NASA Astrophysics Data System (ADS)

Crystallographic faulting in zeolite structures affects both the catalytic and sorption properties, and can greatly complicate attempts at structural characterization. A near extreme example of stacking disorder is provided by zeolite beta, a large pore, high-silica zeolite that was first reported in 1967. We describe here the determination of the framework structure of zeolite beta, using primarily high-resolution electron microscopy, electron diffraction, computer-assisted modelling and powder X-ray diffraction. Zeolite beta can be regarded as a highly intergrown hybrid of two distinct, but closely related structures that both have fully three-dimensional pore systems with 12-rings as the minimum constricting apertures. One end member, polymorph A, forms an enantiomorphic pair, space group symmetries P4_122 and P4_322, with a = 1.25 nm, c = 2.66 nm. Polymorph B is achiral, space group C2/c with a = 1.76 nm, b = 1.78 nm, c = 1.44 nm, ? = 114.5^circ. Both structures are constructed from the same centrosymmetric tertiary building unit (TBU), arranged in layers that, successively, interconnect in either a left- (L) or a right- (R) handed fashion. Polymorph A represents an uninterrupted sequence of RRRR... (or LLLL...) stacking. Polymorph B has an alternating RLRL... stacking sequence. The TBU has no intrinsic preference for either mode of connection, enabling both to occur with almost equal probability in zeolite beta, giving rise to a near random extent of interplanar stacking faults and, to a lesser extent, intraplanar defects terminated by hydroxyl groups. The faulting does not significantly affect the accessible pore volume, but influences the tortuosity of the pore connectivity along the c direction. The high stacking fault densities give rise to complex powder X-ray diffraction (PXD) patterns for zeolite beta materials that comprise both sharp and broad features. By exploiting recursive relations between possible stacking sequences, PXD patterns have been calculated as a function of faulting probability. Reasonable agreement with observed PXD profiles is observed for a ca. 60% faulting probability in the chiral stacking sequence, suggesting a slight preference for polymorph B. The framework building units observed in zeolite beta can also be used to construct other frameworks.

Newsam, J. M.; Treacy, M. M. J.; Koetsier, W. T.; de Gruyter, C. B.

1988-12-01

95

Fundamentals and applications of pervaporation through zeolite membranes  

Microsoft Academic Search

Zeolite membranes have uniform, molecular-sized pores, and they separate molecules based on differences in the molecules’ adsorption and diffusion properties. Zeolite membranes are thus well suited for separating liquid-phase mixtures by pervaporation, and the first commercial application of zeolite membranes has been for dehydrating organic compounds. Because of the large number of zeolites that can be prepared, zeolite membranes have

Travis C. Bowen; Richard D. Noble; John L. Falconer

2004-01-01

96

Synthesis and testing of nanosized zeolite Y  

NASA Astrophysics Data System (ADS)

This work focuses on the synthesis and testing of nanosized zeolite Y. The synthesis formulations of faujasite-type structure of zeolite Y prepared in nanosized form are described. The synthetic zeolite Y is the most widely employed for the preparation of fluid catalytic cracking (FCC) catalysts. The synthesis of zeolite Y is very complicated process. The mean particle size of zeolite Y is 1800 nm. The major challenge of this work involved reducing this average particle size to less than 500 nm. The preliminary experiments were conducted to obtain the pure zeolite Y using the soluble silicates as a silica source. This was achieved by applying the experimental design approach to study the effects of many parameters. The ageing time turned out to be the most significant variable affecting product purity. Based on the preliminary results, a detailed investigation was carried out to determine the effects of silica-alumina precursor preparations on zeolite Y synthesis. Aluminosilicate precursors were prepared by gelling and precipitation of soluble silicate. The as-prepared precursors were used for the hydrothermal synthesis of zeolite Y. The procedure of the precipitation of soluble silicate yielded pure zeolite Y at the conventional synthesis conditions. The extent of purity of zeolite Y depends on the surface areas of aluminosilicate precursors. A novel approach to zeolite Y synthesis was employed for the preparation of the pure nanosized zeolite Y. This was achieved by applying the method of impregnation of precipitated silica. This novel method of impregnation for zeolite Y preparation allows eliminating the vigorous agitation step required for the preparation of a homogeneous silica solution, thereby simplifying the synthesis of zeolite Y in one single vessel. In case of the synthesis of nanosized zeolite Y, the effect of varying the organic templates on the formation of nanosized particles of zeolite Y was investigated, while all other reaction parameters were kept constant. The extent to which the nanosized zeolite Y was formed depended on the types and amount of the organic templates as well as the ageing duration. The activity testing of four FCC catalysts prepared by using CREY (Calcined Rare Earth ion-exchanged) zeolites with different particle sizes was carried out in a fluidized bench-scale batch riser simulator reactor. The starting zeolites NaY of different particle sizes were subjected to two cycles of ion exchange treatment. The particle size of the supported zeolites was varied between 150 and 1800 nm. The preparation of FCC catalysts was conducted by mixing the CREY zeolite with silica-alumina matrix and silica sol binder. Each catalyst contained 25% zeolite. The results of catalytic cracking demonstrated the significant effect of size reduction of the starting zeolite Y on catalytic performance of FCC catalyst. Keywords. Zeolite NaY, Faujasite, Nanosized particles, Nanozeolite, Nanotechnology, Synthesis, Crystallization, Seeding, Ageing, Precipitated silica, Sylopol silica, Fumed silica, Silica sol, Soluble silicates, Alumina, SAR or SiO2/Al2O3 Ratios, Sodium hydroxide, Sodium aluminate, Organic templates, TMAOH, Surfactant (CTAB), Ammonium Sulfate, BET surface area, BJH Pore Size Distribution, Zetasizer Particle Size Distribution, Powder XRD, 27Al Solid-State NMR, Catalytic Impregnation, CREY Zeolite, Silica-Alumina Matrix, Ion Exchange, FCC Catalyst, Catalytic cracking, Riser SimulatorRTM, Steaming, Zeolite HY, Utrastable Zeolite Y (USY)

Karami, Davood

97

Modification in electrical transport with a change in geometry from a nanowire to a nanotube of copper: effect of the extra surface  

NASA Astrophysics Data System (ADS)

We have studied the temperature-dependent (3-300 K) electrical resistance of metal nanowires and nanotubes of the same diameter with the specific aim to understand the changes in electrical transport brought about by a change in the geometry of a nanowire to a nanotube. Single crystalline nanowires and nanotubes of copper were synthesized by electrodeposition in nanoporous alumina templates. The temperature-dependent resistivity data have been analysed using the Bloch-Grüneisen function for the lattice contribution to resistivity, and the characteristic Debye temperature ?R was determined along with the residual resistivity ?0. Substantial size effects were observed in both the parameters ?0 and ?R, where the former is enhanced and the latter is suppressed from bulk to nanowires and further to nanotubes. It has been observed that the transport parameters in the nanotubes with wall thickness t are similar to those of a nanowire with diameter d, where d ? 2t in the specific size range used in this work. It is suggested that appreciable size effects in the electrical transport parameters occur due to the extra surface in the nanotube. In both nanotubes and nanowires, the single parameter that determines the size effect is the surface area to volume ratio.

Venkata Kamalakar, M.; Raychaudhuri, A. K.

2012-04-01

98

Modifications on the hydrogen bond network by mutations of Escherichia coli copper efflux oxidase affect the process of proton transfer to dioxygen leading to alterations of enzymatic activities  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Proton transfer pathway to dioxygen in CueO was identified. Black-Right-Pointing-Pointer Glu506 is the key amino acid to transport proton. Black-Right-Pointing-Pointer The Ala mutation at Glu506 formed a compensatory proton transfer pathway. Black-Right-Pointing-Pointer The Ile mutation at Glu506 shut down the hydrogen bond network. -- Abstract: CueO has a branched hydrogen bond network leading from the exterior of the protein molecule to the trinuclear copper center. This network transports protons in the four-electron reduction of dioxygen. We replaced the acidic Glu506 and Asp507 residues with the charged and uncharged amino acid residues. Peculiar changes in the enzyme activity of the mutants relative to the native enzyme indicate that an acidic amino acid residue at position 506 is essential for effective proton transport. The Ala mutation resulted in the formation of a compensatory hydrogen bond network with one or two extra water molecules. On the other hand, the Ile mutation resulted in the complete shutdown of the hydrogen bond network leading to loss of enzymatic activities of CueO. In contrast, the hydrogen bond network without the proton transport function was constructed by the Gln mutation. These results exerted on the hydrogen bond network in CueO are discussed in comparison with proton transfers in cytochrome oxidase.

Kajikawa, Takao; Kataoka, Kunishige [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)] [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan); Sakurai, Takeshi, E-mail: tsakurai@se.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)] [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)

2012-05-25

99

Single and Multiple Heteroatom Incorporation in MFI Zeolites  

E-print Network

for modulating acid strength and enhancing catalytic properties respectively. Three specific systems were studied: MFI zeolites with simultaneous incorporation of germanium and aluminum (i.e. Ge-Al-MFI zeolites), MFI zeolites with simultaneous incorporation...

Garcia Vargas, Nataly

2012-11-05

100

UTILITY OF ZEOLITES IN HAZARDOUS METAL REMOVAL FROM WATER  

EPA Science Inventory

Zeolites are well known for their ion exchange, adsorption and acid catalysis properties. Different inorganic pollutants have been removed from water at room temperature by using synthetic zeolites. Zeolite Faujasite Y has been used to remove inorganic pollutants including arseni...

101

The influence of using Jordanian natural zeolite on the adsorption, physical, and mechanical properties of geopolymers products.  

PubMed

Geopolymers consist of an amorphous, three-dimensional structure resulting from the polymerization of aluminosilicate monomers that result from dissolution of kaolin in an alkaline solution at temperatures around 80 degrees C. One potential use of geopolymers is as Portland cement replacement. It will be of great importance to provide a geopolymer with suitable mechanical properties for the purpose of water storage and high adsorption capacity towards pollutants. The aim of this work is to investigate the effect of using Jordanian zeolitic tuff as filler on the mechanical performance and on the adsorption capacity of the geopolymers products. Jordanian zeolitic tuff is inexpensive and is known to have high adsorption capacity. The results confirmed that this natural zeolitic tuff can be used as a filler of stable geopolymers with high mechanical properties and high adsorption capacity towards methylene blue and Cu(II) ions. The XRD measurements showed that the phillipsite peaks (major mineral constituent of Jordanian zeolite) were disappeared upon geopolymerization. The zeolite-based geopolymers revealed high compressive strength compared to reference geopolymers that employ sand as filler. Adsorption experiments showed that among different geopolymers prepared, the zeolite-based geopolymers have the highest adsorption capacity towards methylene blue and copper(II) ions. PMID:19036505

Yousef, Rushdi Ibrahim; El-Eswed, Bassam; Alshaaer, Mazen; Khalili, Fawwaz; Khoury, Hani

2009-06-15

102

Synthesis of highly selective zeolite topology molecular sieve for adsorption of benzene gas  

NASA Astrophysics Data System (ADS)

Shangdong ?y ash (SFA), Fangshan ?y ash (FFA) and Heilongjiang ?y ash (HFA) were selected as the raw materials to be used for synthesis of highly selective zeolite topology molecular sieve. Twice foaming method was studied in terms of synthetic zeolite. The experimental products were characterized by means of X-ray ?uorescence (XRF), scanning electron microscope (SEM), X-ray diffraction (XRD), and automated surface area & pore size analyser. The results indicated that 10 M NaOH was chosen as modification experiment condition to process SFA. Crystallization temperature and time were 140 °C and 8 h, respectively. Zeolite topology molecular sieve was prepared with Si/Al molar ratio of 7.9, and its adsorption ratio of benzene gas was up to 66.51%.

Wei, Lin; Chen, Yunlin; Zhang, Baoping; Zu, Zhinan

2013-02-01

103

Increased thermal conductivity monolithic zeolite structures  

DOEpatents

A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

Klett, James (Knoxville, TN); Klett, Lynn (Knoxville, TN); Kaufman, Jonathan (Leonardtown, MD)

2008-11-25

104

UTILITY OF ZEOLITES IN ARSENIC REMOVAL FROM WATER  

EPA Science Inventory

Zeolites are well known for their ion exchange and adsorption properties. So far the cation exchanger properties of zeolites have been extensively studied and utilized. The anion exchanger properties of zeolites are less studied. Zeolite Faujasite Y has been used to remove arseni...

105

Dual zeolite fluid cracking catalyst composition for improved gasoline octane  

Microsoft Academic Search

A fluid cracking catalyst is described useful for the production of high octane gasoline comprising a hydrothermally or chemically stabilized Y zeolite component and a stabilized Omega zeolite component having a silica to alumina ratio greater than 15 wherein the weight ratio of the Y zeolite to the stabilized Omega zeolite is 1:3 to 20: 1, said catalyst not having

Gatte

1993-01-01

106

Durability of Hydrophilic and Antimicrobial Zeolite Coatings under Water Immersion  

E-print Network

Durability of Hydrophilic and Antimicrobial Zeolite Coatings under Water Immersion Cory O-exchanged zeolite A (Ag-ZA) coatings have been shown to have excellent hydrophilicity and are highly antimicrobial Keywords: zeolite coating, zeolite A, hydrophilic, antimicrobial, gravity Introduction Condensing heat

Chen, Wilfred

107

Mechanistic principles of nanoparticle evolution to zeolite crystals  

E-print Network

ARTICLES Mechanistic principles of nanoparticle evolution to zeolite crystals TRACY M. DAVIS1 and building units of silicalite-1, an all-silica zeolite prototype for templated crystal growth. The potential to control nucleation and growth of preferentially oriented zeolite thin films11 and to tailor zeolite

Kokkoli, Efie

108

Silver supported on natural Mexican zeolite as an antibacterial material  

Microsoft Academic Search

The antimicrobial effect of the Mexican zeolitic mineral from Taxco, Guerrero exchanged with silver ions was investigated. The zeolitic mineral as well as sodium and silver zeolitic minerals were characterized by using X-ray diffraction, electron microscopy and IR spectroscopy techniques. The elementary composition of the zeolitic mineral was determined by atomic absorption and microanalyses (EDAX). Escherichia coli and Streptococcus faecalis

M Rivera-Garza; M. T Olgu??n; I Garc??a-Sosa; D Alcántara; G Rodr??guez-Fuentes

2000-01-01

109

Copper hypersensitivity.  

PubMed

The world production of copper is steadily increasing. Although humans are widely exposed to copper-containing items on the skin and mucosa, allergic reactions to copper are only infrequently reported. To review the chemistry, biology and accessible data to clarify the implications of copper hypersensitivity, a database search of PubMed was performed with the following terms: copper, dermatitis, allergic contact dermatitis, contact hypersensitivity, contact sensitization, contact allergy, patch test, dental, IUD, epidemiology, clinical, and experimental. Human exposure to copper is relatively common. As a metal, it possesses many of the same qualities as nickel, which is a known strong sensitizer. Cumulative data on subjects with presumed related symptoms and/or suspected exposure showed that a weighted average of 3.8% had a positive patch test reaction to copper. We conclude that copper is a very weak sensitizer as compared with other metal compounds. However, in a few and selected cases, copper can result in clinically relevant allergic reactions. PMID:25098945

Fage, Simon W; Faurschou, Annesofie; Thyssen, Jacob P

2014-10-01

110

Salt-thermal zeolitization of fly ash.  

PubMed

The molten-salt method has been recently proposed as a new approach to zeolitization of fly ash. Unlike the hydrothermal method, this method employs salt mixtures as the reaction medium without any addition of water. In this study, systematic investigation has been conducted on zeolitization of fly ash in a NaOH-NaNO3 system in order to elucidate the mechanism of zeolite formation and to achieve its optimization. Zeolitization of fly ash was conducted by thermally treating a powder mixture of fly ash, NaOH, and NaNO3. Zeolitization of fly ash took place above 200 degrees C, a temperature lower than the melting points of salt and base in the NaOH-NaNO3 system. However, it was uncertain whether the reactions took place in a local molten state or in a solid state. Therefore, the proposed method is renamed the "salt-thermal" method rather than the "molten-salt" method. Mainly because of difficulty in mobility of components in salt mixtures, zeolitization seems to occur within a local reaction system. In situ rearrangement of activated components seems to lead to zeolite formation. Particle growth, rather than crystal growth through agglomeration, resulted in no distinct morphologies of zeolite phases. Following are the optimal zeolitization conditions of the salt-thermal method: temperature, 250-350 degrees C; time, 3-12 h; weight ratio of NaOH/NaNO3, 0.3-0.5; weight ratio of NaNO3/fly ash, 0.7-1.4. Therefore, it is clear from this work that the salt-thermal method could be applied to massive zeolitization of fly ash as a new alternative method for recycling this waste. PMID:11452614

Choi, C L; Park, M; Lee, D H; Kim, I E; Park, B Y; Choi, J

2001-07-01

111

Zeolitic Materials, Vol. 3, No. 1, December 2002, 20-28 20 Copyright 2002 Korean Zeolite Association  

E-print Network

Zeolitic Materials, Vol. 3, No. 1, December 2002, 20-28 20 Copyright ¨Ï 2002 Korean Zeolite activity than ZSM-5 zeolite, and also has higher catalytic stability than MCM-41- SO3H. Keywords: Periodic. / Synthesis and Alkylation of Phenol over PMO-SO3H Zeolitic Materials, Vol. 3, No. 1, December 2002 21

Kim, Ji Man

112

Zeolitic Materials, Vol. 3, No. 1, December 2002, 29-35 Copyright 2002 Korean Zeolite Association 29  

E-print Network

Zeolitic Materials, Vol. 3, No. 1, December 2002, 29-35 Copyright ¨Ï 2002 Korean Zeolite Association 29 Etherification Reaction of 2-Naphtol with Ethanol Using Dealuminated Beta Zeolite Jin Won Kim Korea *To whom correspondence should be addressed. E-mail: Yie@ajou.ac.kr ABSTRACT Zeolite H

Kim, Ji Man

113

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites.  

PubMed

In addition to their well-known uses as catalysts, zeolites are utilized to adsorb and remove various cations from aqueous system. The adsorption of the cations is ascribed to the negative charge of zeolites derived from isomorphous substitution of Si by Al. The amount of Na+ adsorption on 4A, X, Y, Na-P1 and mordenite type zeolites were determined in aqueous media, in a two-cation (Na+ and H+) system. Although each zeolite has a constant amount of negative charge, the amount of Na+ adsorption of each zeolite decreased drastically at low pH-pNa values, where pH-pNa is equal to log{(Na+)/(H+)}. By using the plot of the amount of Na+ adsorption versus pH-pNa, an index of the H+ selectivity, which is similar to the pKa of acids, of each zeolite was estimated, and the index tended to increase with decreasing Si/Al ratio of zeolites. These indicate that zeolites with lower Si/Al and higher negative charge density have higher H+ adsorption selectivity, and in fact, such a zeolite species (4A and X) adsorbed considerable amount of H+ even at weakly alkaline pH region. The adsorption of H+ results in the decrease of cation adsorption ability, and may lead to the dissolution of zeolites in aqueous media. PMID:25493632

Munthali, Moses Wazingwa; Elsheikh, Mohammed Abdalla; Johan, Erni; Matsue, Naoto

2014-01-01

114

An ESCA study of rhodium(III)-exchanged zeolite catalysts  

SciTech Connect

An ESCA study of rhodium(III)-exchanged zeolite catalysts which are active in hydrogenation and other reactions, showed that activation at 300/sup 0/C and 0.002 mm Hg reduced rhodium(III) in Y zeolite to metallic rhodium but did not affect rhodium(III) in A zeolite. This reduction occurred under milder conditions than known for other metal ions in zeolites, and the reduced species is probably the active catalyst in rhodium-exchanged zeolite.

Kuznicki, S.M.; Eyring, E.M.

1980-09-01

115

Studies on secondary synthesis and characterisation of boron-modified ZSM-5 zeolites  

Microsoft Academic Search

A post synthesis modification (“secondary synthesis”) of aluminosilicates has been described in order to produce boron-containing zeolites of the pentasile type: Isomorphic incorporation of boron is verified by means of 11B MAS NMR spectroscopy, laser ablation ICP AES and X-ray powder diffraction. 27Al MAS NMR spectroscopy is used for further characterisation of the resulting material. In order to create lattice

Brit Meier; Wladimir Reschetilowski

1994-01-01

116

Kinetics of the hydroxylation of benzene with N 2O on modified ZSM-5 zeolites  

Microsoft Academic Search

A detailed kinetic study of the hydroxylation of benzene to phenol using nitrous oxide (N2O) is performed on different, well characterised modifications of ZSM-5 type zeolites. After process studies in a fixed bed reactor for the first time a recycle reactor (Berty-type) is successfully used in direct measurements of the molar rates of reactant consumption and product formation. From those

A. Reitzmann; E. Klemm; G. Emig

2002-01-01

117

Copper Metallochaperones  

PubMed Central

The current state of knowledge on how copper metallochaperones support the maturation of cuproproteins is reviewed. Copper is needed within mitochondria to supply the CuA and intramembrane CuB sites of cytochrome oxidase, within the trans-Golgi network to supply secreted cuproproteins and within the cytosol to supply superoxide dismutase 1 (Sod1). Subpopulations of copper-zinc superoxide dismutase also localize to mitochondria, the secretory system, the nucleus and, in plants, the chloroplast, which also requires copper for plastocyanin. Prokaryotic cuproproteins are found in the cell membrane and in the periplasm of gram-negative bacteria. Cu(I) and Cu(II) form tight complexes with organic molecules and drive redox chemistry, which unrestrained would be destructive. Copper metallochaperones assist copper in reaching vital destinations without inflicting damage or becoming trapped in adventitious binding sites. Copper ions are specifically released from copper metallochaperones upon contact with their cognate cuproproteins and metal transfer is thought to proceed by ligand substitution. PMID:20205585

Robinson, Nigel J.; Winge, Dennis R.

2014-01-01

118

Nanocrystalline zeolite beta and zeolite Y as catalysts in used palm oil cracking for the production of biofuel  

Microsoft Academic Search

Nanocrystalline zeolites with crystal size smaller than 100 nm are potential replacement for conventional zeolite catalysts\\u000a due to their unique characteristics and advantages. In this study, the synthesis of nanocrystalline zeolite Y (FAU) and nanocrystalline\\u000a zeolite beta (BEA) under hydrothermal conditions is reported. The effect of crystal size on the physico-chemical characteristics\\u000a of the zeolite, Y (FAU), and beta (BEA) is

Niken Taufiqurrahmi; Abdul Rahman Mohamed; Subhash Bhatia

119

Electroless deposition of copper and fabrication of copper micropatterns on CVD diamond film surfaces  

NASA Astrophysics Data System (ADS)

Electroless deposition of copper on as-grown and amino-modification diamond substrates was investigated. The compact and uniform copper films were successfully electrolessly deposited on as-grown and amino-modification diamond substrates after activation by Pd/Sn colloid nanoparticles. The adhesion interaction between copper films and diamond substrates was roughly estimated by the ultrasonic treatment. The results showed the higher adhesion interaction between copper films and amino-modification diamond substrates than that between the copper films and as-grown diamond substrates due to the greater attractive force between the Pd/Sn colloid nanoparticles and amino-modified diamond surface. The favorable copper micropatterns were successfully constructed on diamond film surfaces by means of the catalyst lift-off method and the copper lift-off method. Furthermore, the electrochemical behavior of copper-modified boron-doped diamond (BDD) was studied for glucose oxidation in 0.2 M sodium hydroxide solution by using cyclic voltammetry, and the result indicated that copper-modified BDD exhibited high catalytic activity to electrochemical oxidation of glucose in alkaline media.

Zhao, Jianwen; Tian, Ruhai; Zhi, Jinfang

2008-03-01

120

Zeolites on Mars: Prospects for Remote Sensing  

NASA Technical Reports Server (NTRS)

The Martian surface composition measured by Viking can be represented by several combinations of minerals incorporating major fractions of zeolites known to occur in altered mafic rocks and polar soils on Earth. The abundant occurrence of zeolites on Mars is consistent with what is known about both the physical and chemical environment of that planet. The laboratory reflectance spectra (0.65 to 2.55 microns) of a number of relatively pure zeolite minerals and some naturally occurring zeolite-clay soils were measured. All of the spectra measured are dominated by strong absorption near 1.4 and 1.9 microns and a steep reflectance drop longward of about 2.2 microns, all of which are due to abundant H2O. Weaker water overtone bands are also apparent, and in most cases there is spectral evidence for minor Fe(3+). In these features the zeolite spectra are similar to spectra of smectite clays which have abundant interlayer water. The most diagnostic difference between clay and zeolite spectra is the total absence in the zeolites of the weak structural OH absorption.

Gaffney, E. S.; Singer, R. B.; Kunkle, T. D.

1985-01-01

121

Preparation and characterization of zeolitic membrane  

SciTech Connect

Zeolites with less than 10 {angstrom} pores are desirable membrane materials, due to their crystallinity, resistance to high temperature, and chemical inertness. Although several works have been done on them, zeolitic membranes have not been developed so perfect at present. In this paper, the authors reported the preparation and some properties of an asymmetric zeolitic membrane synthesized by hydrothermal process on the intermediate layer which was made on a porous ceramic support, meanwhile the results of separation of ethanol-water mixture on pervaporation were discussed.

Shuanshi Fan; Chunhua Li; Jinqu Wang [Dalian Univ. of Technology (China)

1994-12-31

122

Structural diversity of lamellar zeolite Nu-6(1)--postsynthesis of delaminated analogues.  

PubMed

Nu-6(1) zeolite, the lamellar precursor of NSI topology, was firstly synthesized with 4'4-bipyridine as the structure-directing agent (SDA) and then subjected to HCl-EtOH treatment for the purpose of structural modification. Interlayer deconstruction and reconstruction took place alternately in this acid treatment. An intermediate named ECNU-4 was separated at the initial stage of this continuous treatment process, which exhibited a special X-ray diffraction pattern without obvious reflection peaks at low angles. The zeolitic structure in the intralayer sheets was supposed to be well preserved in ECNU-4, whereas the interlayer structure became extremely disordered. The ECNU-4 intermediate showed structural diversity. It was converted into the reconstructed and interlayer expanded zeolite IEZ-NSI without an external silicon source by prolonging the HCl-EtOH treatment to 24 h. Moreover, with a partially delaminated structure, ECNU-4 was easily interlayer swollen at room temperature with cetyltrimethyl ammonium bromide in the presence of tetrapropyl ammonium hydroxide. The swollen material was further sonicated to yield a more deeply delaminated zeolite, Del-Nu-6. ECNU-4 and Del-Nu-6 differed in delamination degree, structural disordering and textural properties, especially surface area. PMID:24658572

Xu, Hao; Jia, Lili; Wu, Haihong; Yang, Boting; Wu, Peng

2014-07-21

123

Synthesis and characterisation of chiral Cu(I) complexes with substituted-pyrrolidine-ligands bearing a triethoxysilyl group and preparation of heterogenised catalysts on USY-zeolites  

Microsoft Academic Search

A series of new copper complexes of formula [Cu(L-L) (CH3CN)]X (X = ClO4, PF6 where L-L = (S)-2-R-pyrrolidine (1), (S)-1-R-2-t-butylaminocarbonylpyrrolidine (2), (S)-1-R-2-(1-naphthylaminocarbonyl)pyrrolidine (3), (S)-1-R-2-(1-naphthylaminomethyl)pyrrolidine (4), (2S,4S)-4-amino-1-R-2-t-butylaminocarbonylpyrrolidine (5) (R = (3-triethoxysilylpropyl)aminocarbonyl) have been prepared, characterised and supported on a modified ultrastable Y-zeolite containing supermicropores by a covalent bond. The complexes anchored on the zeolite are easily recycled and show a similar

A. Carmona; A. Corma; M. Iglesias; F. Sánchez

1996-01-01

124

Modified 8-ring zeolites as catalysts  

SciTech Connect

A catalyst composition is described for conversion of methanol and/or dimethylether and ammonia to dimethylamine, comprising at least one modified acidic zeolite selected from the group consisting of chabazite erionite, ZK-5, and rho, the zeolite having been modified by treatment with one or more compounds containing at least one element selected from the group consisting of silicon, aluminum, phosphorus, and boron, to deposit substantially on the external surfaces thereof at least 0.5 weight percent of the element.

Bergna, H.E.; Corbin, D.R.; Sonnichsen, G.C.

1988-06-21

125

Multicomponent ion-exchange equilibria in chabazite zeolite  

SciTech Connect

Efficient design ion-exchange columns, using Ionsiv IE-96 chabazite zeolite, for the decontamination of process wastewater that contains ppB levels of Sr-90 and Cs-137 requires a detailed study of binary and multicomponent ion-exchange equilibria. Experimental isotherms were acquired for Ca--Na, Mg--Na, Sr--Na, Cs--Na, Sr--Cs--Na, Ca--Mg--Na, Sr--Ca--Mg--Na, Cs--Ca--Mg--Na, and Sr--Cs--Ca--Mg--Na comparing batch and column experimental approaches. Binary isotherms obtained by the batch technique were most successfully fitted with a modification of the Dubinin-Polyani equilibrium model. Prediction of the multicomponent equilibria from binary data will require more sophisticated modeling. 15 refs., 5 figs., 3 tabs.

Robinson, S.M.; Arnold, W.D.; Byers, C.H.

1990-01-01

126

Three Mile Island zeolite vitirification demonstration program  

SciTech Connect

The cleanup of the high-activity-level water at Three Mile Island (TMI) provides an opportunity to further develop waste management technology. Approximately 790,000 gallons of high-activity-level water at TMI's Unit-2 Nuclear Power Station will be decontaminated at the site using the submerged demineralizer system (SDS). In the SDS process, the cesium and strontium in the water are sorbed onto zeolite that is contained within metal liners. The Department of Energy has asked the Pacific Northwest Laboratory (PNL) to take a portion of the zeolite from the SDS process and demonstrate, on a production scale, that this zeolite can be vitrified using the in-can melting process. This paper is a brief overview of the TMI zeolite vitrification program. The first section discusses the formulation of a glass suitable for immobilizing SDS zeolite. The following section describes a feed system that was developed to feed zeolite to the in-can melter. It also describes the in-can melting process and the government owned facilities in which the demonstrations will take place. Finally, the schedule for completing the program activities is outlined.

Siemens, D.H.; Knowlton, D.E.; Shupe, M.W.

1981-06-01

127

Thermodynamic modeling of natural zeolite stability  

SciTech Connect

Zeolites occur in a variety of geologic environments and are used in numerous agricultural, commercial, and environmental applications. It is desirable to understand their stability both to predict future stability and to evaluate the geochemical conditions resulting in their formation. The use of estimated thermodynamic data for measured zeolite compositions allows thermodynamic modeling of stability relationships among zeolites in different geologic environments (diagenetic, saline and alkaline lakes, acid rock hydrothermal, basic rock, deep sea sediments). This modeling shows that the relative cation abundances in both the aqueous and solid phases, the aqueous silica activity, and temperature are important factors in determining the stable zeolite species. Siliceous zeolites (e.g., clinoptilolite, mordenite, erionite) present in saline and alkaline lakes or diagenetic deposits formed at elevated silica activities. Aluminous zeolites (e.g., natrolite, mesolite/scolecite, thomsonite) formed in basic rocks in association with reduced silica activities. Likewise, phillipsite formation is favored by reduced aqueous silica activities. The presence of erionite, chabazite, and phillipsite are indicative of environments with elevated potassium concentrations. Elevated temperature, calcic water conditions, and reduced silica activity help to enhance the laumontite and wairakite stability fields. Analcime stability increases with increased temperature and aqueous Na concentration, and/or with decreased silica activity.

Chipera, S.J.; Bish, D.L.

1997-06-01

128

Tailoring the structure of hierarchically porous zeolite beta through modified orientated attachment growth in a dry gel system.  

PubMed

The crystallization of zeolite beta in a dry gel system is found to follow the orientated attachment growth route, escorted with a temporal morphology change from bulky gel, through aggregation of the particulate to large zeolitic crystals. Modification of the precrystallized gel with organosilanes can be used to tune the morphology of the ultimate beta. When hexadecyltrimethoxysilane (HTS) is employed to modify precrystallized gel, a resumed secondary growth produces a hybrid mesocrystal of agglomerated nanozeolites. Combustive removal of organics leads to the formation of hierarchically porous zeolite beta of 100 to 160?nm, composed of nanocrystal building units ranging from 20 to 40?nm, with a noticeable micropore volume of 0.19?mL?g(-1) and a meso/macropore size between 5 and 80?nm. Conversely, when 1,8-bis(triethoxysilyl)octane (BTO) is utilized to modify the same precrystallized gel, assemblages of discrete beta nanozeolite of around 35?nm are generated. These assemblages construct a hierarchical zeolite beta with a micropore volume of 0.20?mL?g(-1) and auxiliary pores ranging from 5 to 100?nm. Both organosilanes bring about well-connected hierarchical pore networks. HTS has little effect on the Brønsted/Lewis acidity, whereas BTO causes a substantial reduction of strong Brønsted acid sites. The hierarchical beta zeolite-supported Pt catalyst exhibits improved catalytic performance for the hydroisomerization of n-heptane. PMID:25233842

Chen, Jiao; Hua, Weiming; Xiao, Yu; Huo, Qisheng; Zhu, Kake; Zhou, Xinggui

2014-11-01

129

The zeolite deposits of Greece  

USGS Publications Warehouse

Zeolites are present in altered pyroclastic rocks at many localities in Greece, and large deposits of potential economic interest are present in three areas: (1) the Evros region of the province of Thrace in the north-eastern part of the Greek mainland; (2) the islands of Kimolos and Poliegos in the western Aegean; and (3) the island of Samos in the eastern Aegean Sea. The deposits in Thrace are of Eocene-Oligocene age and are rich in heulandite and/or clinoptilolite. Those of Kimolos and Poliegos are mainly Quaternary and are rich in mordenite. Those of Samos are Miocene, and are rich in clinoptilolite and/or analcime. The deposits in Thrace are believed to have formed in an open hydrological system by the action of meteoric water, and those of the western Aegean islands in a similar way but under conditions of high heat flow, whereas the deposits in Samos were formed in a saline-alkaline lake.

Stamatakis, M.G.; Hall, A.; Hein, J.R.

1996-01-01

130

Powder Diffraction in Zeolite Science  

NASA Astrophysics Data System (ADS)

This tutorial discusses the fundamental principles of X-ray diffraction and its applications in zeolite science. The early sections review the physics of diffraction, crystal symmetry, and reciprocal space. We discuss how the intensity of diffracted radiation is affected both by geometric effects involving detection (the Lorentz-polarization factor) and by the arrangement of atoms within the crystal (the structure factor). The differences between powder diffraction and single-crystal diffraction are then described, and differences between X-ray and neutron diffraction are also discussed. Later sections describe the effects of symmetry, lattice substitution, crystallite size, residual strain, preferred orientation, and X-ray absorption. Special emphasis is placed on the proper application of the Scherrer analysis in reporting crystalize size. The principles of structure solution from direct methods and Patterson methods are then introduced, and a description of Rietveld analysis is given. Finally the effects of stacking disorder on a powder diffraction pattern are presented.

Burton, Allen W.

131

Simultaneous determination of arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in fertilizers by microwave acid digestion and inductively coupled plasma-optical emission spectrometry detection: single-laboratory validation of a modification and extension of AOAC 2006.03.  

PubMed

A single-laboratory validation study was conducted for the simultaneous determination of arsenic, cadmium, calcium, cobalt, copper, chromium, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in all major types of commercial fertilizer products by microwave digestion and inductively coupled plasma-optical emission spectroscopy analysis. This validation study proposes an extension and modification of AOAC 2006.03. The extension is the inclusion of calcium, copper, iron, magnesium, manganese, and zinc, and the modification is incorporation of hydrochloric acid in the digestion system. This dual acid digestion utilizes both hydrochloric and nitric acids in a 3 to 9 mL volume ratio/100 mL. In addition to 15 of the 30 original validation materials used in the 2006.03 collaborative study, National Institute of Standards and Technology Standard Reference Material 695 and Magruder 2009-06 were incorporated as accuracy materials. The main benefits of this proposed method are a significant increase in laboratory efficiency when compared to the use of both AOAC Methods 965.09 and 2006.03 to achieve the same objective and an enhanced recovery of several metals. PMID:25051614

Webb, Sharon; Bartos, James; Boles, Rhonda; Hasty, Elaine; Thuotte, Ethel; Thiex, Nancy J

2014-01-01

132

Dual zeolite fluid cracking catalyst composition for improved gasoline octane  

SciTech Connect

A fluid cracking catalyst is described useful for the production of high octane gasoline comprising a hydrothermally or chemically stabilized Y zeolite component and a stabilized Omega zeolite component having a silica to alumina ratio greater than 15 wherein the weight ratio of the Y zeolite to the stabilized Omega zeolite is 1:3 to 20: 1, said catalyst not having a hydrogenation component. A fluid cracking catalyst is described according to claim 1, wherein the fluid cracking catalyst comprises either (a) a composite of a Y zeolite and a stabilized Omega zeolite in an inorganic matrix, or (b) a mixture of a matrixed Y zeolite component and a matrixed stabilized Omega zeolite component.

Gatte, R.R.

1993-08-17

133

Low-temperature synthesis of zeolite from perlite waste — Part II: characteristics of the products  

NASA Astrophysics Data System (ADS)

The paper investigates the properties of sodium zeolites synthesized using the hydrothermal method under autogenous pressure at low temperature with NaOH solutions of varying concentrations. During this modification, zeolites X, Na-P1 and hydroxysodalite were synthesized. The synthesis parameters, and thus, phase composition of resulting samples, significantly affected the specific surface area (SSA) and cation exchange capacity (CEC). SSA increased from 2.9 m2/g to a maximum of 501.2 m2/g, while CEC rose from 16 meq/100 g to a maximum of 500 meq/100 g. The best properties for use as a sorbent were obtained for perlite waste modified with 4.0 M NaOH at 70 °C or 80 °C.

Król, Magdalena; Morawska, Justyna; Mozgawa, W?odzimierz; Pichór, Waldemar

2014-11-01

134

Low-temperature synthesis of zeolite from perlite waste — Part II: characteristics of the products  

NASA Astrophysics Data System (ADS)

The paper investigates the properties of sodium zeolites synthesized using the hydrothermal method under autogenous pressure at low temperature with NaOH solutions of varying concentrations. During this modification, zeolites X, Na-P1 and hydroxysodalite were synthesized. The synthesis parameters, and thus, phase composition of resulting samples, significantly affected the specific surface area (SSA) and cation exchange capacity (CEC). SSA increased from 2.9 m2/g to a maximum of 501.2 m2/g, while CEC rose from 16 meq/100 g to a maximum of 500 meq/100 g. The best properties for use as a sorbent were obtained for perlite waste modified with 4.0 M NaOH at 70 °C or 80 °C.

Król, Magdalena; Morawska, Justyna; Mozgawa, W?odzimierz; Pichór, Waldemar

2014-12-01

135

Studies in reduction-roast leaching ion exchange of copper converter slag from an Indian copper complex, Ghatshila  

SciTech Connect

Large quantities of converter and anode slags are generated in different unit operations for the production of copper in I.C.C. Ghatshila. The converter slag contains about 2.75% copper, 0.9% nickel, 52.0% iron, and 0.6% cobalt and cannot be rejected due to its economic importance. X-ray diffraction (XRD) studies revealed the presence of copper in elemental, oxide, and silicate phases and iron in silicate (Feyalite) and oxide (Fe{sub 2}O{sub 3}) phases. From the earlier work on leaching by an acetic acid lixiviant up to 55% copper could be extracted at 250 mL of acetic acid/100 g of slag, 125 C temperature, and 35 atm of oxygen pressure. Low copper recovery was attributed to the presence of copper silicate and sulfide phases which could not be detected by XRD. Therefore, reduction roasting by noncoking coal was done to increase the copper recovery. A coal sample from Talchar which contained 30% fixed carbon, 40% volatile, and 30% ash was used for reduction roasting. Maximum percent extraction of copper and nickel (97% Cu and 20% Ni) could be achieved at the temperature of 720 C for 90 min of roasting with 20% reductant. The acetic acid requirement was 130 mL/100 g of reduced pellets, while leaching at the oxygen pressure of 35 atm for 120 min at 120 C. Iron dissolution was minimum (max 1%) in all the experiments. The ion-exchange technique was employed to separate copper from acetate solution. Zeolite resin was found to be suitable for the separation of copper from leach liquor. About 92% copper was recovered by geolite. 2.5 N H{sub 2}SO{sub 4} was found to be most effective for the stripping of the copper from resin.

Bodas, M.G.; Mathur, S.B. [National Metallurgical Lab., Jamshedpur (India). Non-Ferrous Process Div.] [National Metallurgical Lab., Jamshedpur (India). Non-Ferrous Process Div.

1997-12-01

136

Zeolite content determination in kaolinic clays via thermal effects  

Microsoft Academic Search

For application in catalysis and adsorption processes, zeolites are synthesized on the surface of spray-dried kaolin microspheres. Various thermal effects are used for the rapid characterization of the zeolite type and content. From DTA measurements, the exothermic lattice break-down peak gives information on the zeolite type and the thermal stability of the sample. Measurements of the heats of immersion by

I. W. Schulz; U. Illgen; J. Scheve; K.-D. Backhaus

1988-01-01

137

Recent Developments in Zeolite-like Materials Synthesis and Characterisation  

Microsoft Academic Search

In the last few years considerable effort has been directed at the targeted synthesis of zeolites and zeolite-like microporous materi- als with predetermined physical and catalytic properties. With new computational techniques, it has become possible to design tem- plates for the synthesis of specific microporous structures with de- sired pore size and connectivities. With regard to zeolite-like mate- rials, much

1999-01-01

138

Microstructural Optimization of a Zeolite Membrane for Organic  

E-print Network

#12;Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation Zhiping Lai,1 growth method for the fabrication of high-permeance, high-separa- tion-factor zeolite (siliceous ZSM-5, such as twin overgrowths and random nucleation. Organic polycations are used as zeolite crystal shape modifiers

Kokkoli, Efie

139

Synthesis of zeolite beta in fluoride media under microwave irradiation  

E-print Network

Synthesis of zeolite beta in fluoride media under microwave irradiation Dae Sung Kim a , Jong 2003; received in revised form 28 November 2003; accepted 29 November 2003 Abstract Zeolite beta has of zeolite beta. In particular, microwave technique combined with fluoride species and seeding led to more

Kim, Ji Man

140

Cesium incorporation and diffusion in cancrinite, sodalite, zeolite, and allophane  

E-print Network

Cesium incorporation and diffusion in cancrinite, sodalite, zeolite, and allophane Jarai Mon of silicate minerals and precipitation of new aluminosilicate minerals. Cancrinite, sodalite, LTA zeolite in sodalite and cancrinite was far more difficult to replace than that in LTA zeolite or allophane. Most

Flury, Markus

141

Zeolite membranes – state of their development and perspective  

Microsoft Academic Search

An ideal zeolite membrane combines the general advantages of inorganic membranes (temperature stability, solvent resistance) with a perfect shape selectivity. Due to their “molecular sieve” function, zeolite membranes can principally discriminate the components of gaseous or liquid mixtures dependent on their molecular size. This molecular sieving principle requires a pinhole- and crack-free zeolite membrane. Remarkable separation effects can also be

J Caro; M Noack; P Kölsch; R Schäfer

2000-01-01

142

Diameter and Chirality Distribution of SWNTs Grown from Zeolite Surfaces  

E-print Network

Diameter and Chirality Distribution of SWNTs Grown from Zeolite Surfaces Yoichi Murakami1-8656 Zeolites are microporous, crystalline aluminosilicates constructed from tetrahedral base units. We have been using the b-surfaces of silicalite-1 zeolite (framework: MFI) as catalyst support for catalytic

Maruyama, Shigeo

143

MATERIALS, INTERFACES, AND ELECTROCHEMICAL PHENOMENA Hydrophilic Zeolite Coatings for Improved  

E-print Network

MATERIALS, INTERFACES, AND ELECTROCHEMICAL PHENOMENA Hydrophilic Zeolite Coatings for Improved Heat on the surface of a bare, ZSM-5 coated, and Zeolite-A coated stainless steel 304 substrate at different initial surface temperatures was experimentally studied. ZSM-5 and Zeolite-A coated SS-304 are more much more

Aguilar, Guillermo

144

Zeolite-templated Pt/C electrocatalysts  

SciTech Connect

In an effort to reduce the amount of platinum required in low temperature fuel cells, we have prepared electrocatalysts of platinum nanoparticles-on-carbon through zeolite-templating methods. Several different zeolite structure-types, as well as clays and mesoporous silicas were investigated as hosts for the preparation of small Pt clusters through thermal decomposition of ion exchanged (NH{sub 3}){sub 4}Pt{sup 2+}. Several factors relating to cluster confinement and mobility influence cluster size, and clusters below 1 nm with narrow size distribution have been prepared. To enable electrochemical application, the pores of the Pt cluster-containing zeolite were filled with electrically conductive carbon via infiltration with carbon precursors, polymerization, and pyrolysis. The zeolite host was then removed by acid digestion, to leave a micro-/mesoporous Pt/C electrocatalyst possessing Pt clusters of controlled size. Preliminary electrochemical evaluation of these catalysts is reported. The energetics of thermal decomposition of (NH{sub 3}){sub 4}Pt{sup 2+} to form Pt clusters in zeolite X have been investigated through Differential Scanning Calorimetry, and apparent activation energies calculated. The relationship between (NH{sub 3}){sub 4}Pt{sup 2+} decomposition and conditions of calcination has been explored in an effort to better control Pt cluster sizes.

Coker, Eric N.; Steen, William A.; Miller, James E. (Sandia)

2008-06-16

145

Adsorption of nitrosamines by mesoporous zeolite.  

PubMed

On the basis of a study of the adsorption of zeolite and mesoporous silica, we attempted to create a hierarchical structure in the new nitrosamines trapper. Thus, mesoporous HZSM-5 zeolite was fabricated through impregnating a structure-directing agent into the as-synthesized MCM-41 followed by dry-gel conversion to transform amorphous silica to zeolite crystal. The texture of mesoporous ZSM-5 was tailored by adjusting the Si/Al ratio in the MCM-41 source and the thermal treatment time. The resulting samples were characterized by N(2) adsorption to evaluate their textural properties. One volatile nitrosamine, N-nitrosopyrrolidine (NPYR), was used as probe molecule in instantaneous adsorption to survey the function of the resulting composites. Adsorptions of N'-nitrosonornicotine (NNN) in dichloromethane solution and tobacco-specific nitrosamines (TSNA) in tobacco-extract solution were also utilized for the same purpose. As expected, mesoporous zeolite exhibits a good adsorption capacity in laboratory tests, superior to either microporous zeolite or mesoporous silica, providing a valuable candidate for controlling nitrosamines in the environment. PMID:20621826

Lin, Wei Gang; Wei, Feng; Gu, Fang Na; Dong, Xin; Gao, Ling; Zhuang, Ting Ting; Yue, Ming Bo; Zhu, Jian Hua

2010-08-15

146

Italian zeolitized rocks of technological interest  

NASA Astrophysics Data System (ADS)

Large areas of Italian territory are covered by thick and widespread deposits of zeolite-bearing volcaniclastic products. The main zeolites are phillipsite and chabazite spread over the whole peninsula, and clinoptilolite recorded only in Sardinia. A trachytic to phonolitic glassy precursor accounts for the formation of the former zeolites characterized by low Si/Al ratios (?3.00), while clinoptilolite is related to more acidic volcanism. The genesis of most of these zeolitized deposits is linked to pyroclastic flow emplacement mechanisms characterized by quite high temperatures and by the presence of abundant fluids. The main utilization of these materials has been and still is as dimension stones in the building industry. Currently, limited amounts are also employed in animal farming (dietary supplement, pet litter and manure deodorizer) and in agriculture as soil improvement and slow-release fertilizers. New fields of application have been proposed for these products on account of their easy availability, very low cost, their high-grade zeolites (50 70%), and good technological features such as high cation exchange capacities and adsorption properties.

de'Gennaro, M.; Langella, A.

1996-09-01

147

Growth of zeolite crystals in the microgravity environment of space  

NASA Technical Reports Server (NTRS)

Zeolites are hydrated, crystalline aluminosilicates with alkali and alkaling earth metals substituted into cation vacancies. Typically zeolite crystals are 3 to 8 microns. Larger cyrstals are desirable. Large zeolite crystals were produced (100 to 200 microns); however, they have taken restrictively long times to grow. It was proposed if the rate of nucleation or in some other way the number of nuclei can be lowered, fewer, larger crystals will be formed. The microgravity environment of space may provide an ideal condition to achieve rapid growth of large zeolite crystals. The objective of the project is to establish if large zeolite crystals can be formed rapidly in space.

Sacco, A., Jr.; Sand, L. B.; Collette, D.; Dieselman, K.; Crowley, J.; Feitelberg, A.

1986-01-01

148

Towards a sustainable manufacture of hierarchical zeolites.  

PubMed

Hierarchical zeolites have been established as a superior type of aluminosilicate catalysts compared to their conventional (purely microporous) counterparts. An impressive array of bottom-up and top-down approaches has been developed during the last decade to design and subsequently exploit these exciting materials catalytically. However, the sustainability of the developed synthetic methods has rarely been addressed. This paper highlights important criteria to ensure the ecological and economic viability of the manufacture of hierarchical zeolites. Moreover, by using base leaching as a promising case study, we verify a variety of approaches to increase reactor productivity, recycle waste streams, prevent the combustion of organic compounds, and minimize separation efforts. By reducing their synthetic footprint, hierarchical zeolites are positioned as an integral part of sustainable chemistry. PMID:24520034

Verboekend, Danny; Pérez-Ramírez, Javier

2014-03-01

149

Hydrogen Purification Using Natural Zeolite Membranes  

NASA Technical Reports Server (NTRS)

The School of Science at Universidad del Turabo (UT) have a long-lasting investigation plan to study the hydrogen cleaning and purification technologies. We proposed a research project for the synthesis, phase analysis and porosity characterization of zeolite based ceramic perm-selective membranes for hydrogen cleaning to support NASA's commitment to achieving a broad-based research capability focusing on aerospace-related issues. The present study will focus on technology transfer by utilizing inorganic membranes for production of ultra-clean hydrogen for application in combustion. We tested three different natural zeolite membranes (different particle size at different temperatures and time of exposure). Our results show that the membranes exposured at 900 C for 1Hr has the most higher permeation capacity, indicated that our zeolite membranes has the capacity to permeate hydrogen.

DelValle, William

2003-01-01

150

In situ characterisation by anomalous X-ray diffraction of the cationic distribution of dehydrated SrRbX zeolite  

Microsoft Academic Search

An in situ X-ray diffraction cell (consisting in a motorised sample holder and a small tubular furnace) and a methodology implying X-ray anomalous diffusion (method of contrast) were developed to study structural modifications induced by the dehydration of SrRbX zeolite.The experiments realised on beamline D2AM, near and far from both Sr and Rb K-absorption edges, have shown the validity of

C. Pichon; H. Palancher; B. Rebours; J. Lynch; J. F. Bérar; J. L. Hodeau

2004-01-01

151

Crystal engineering of zeolites with graphene  

NASA Astrophysics Data System (ADS)

Achieving control over the morphology of zeolite crystals at the nanoscale is crucial for enhancing their performance in diverse applications including catalysis, sensors and separation. The complexity and sensitivity of zeolite synthesis processes, however, often make such control both highly empirical and difficult to implement. We demonstrate that graphene can significantly alter the morphology of titanium silicalite (TS-1) particles, in particular being able to reduce their dimensions from several hundreds to less than 10 nm. Through electron microscopy and molecular mechanics simulations we propose a mechanism for this change based on the preferential interaction of specific TS-1 surfaces with benzyl-alcohol-mediated graphene. These findings suggest a facile new means of controlling the zeolite morphology and thereby also further demonstrate the potential of graphene in hybrid materials. Moreover, the generality of the mechanism points the way to a new avenue of research in using two-dimensional materials to engineer functional inorganic crystals.Achieving control over the morphology of zeolite crystals at the nanoscale is crucial for enhancing their performance in diverse applications including catalysis, sensors and separation. The complexity and sensitivity of zeolite synthesis processes, however, often make such control both highly empirical and difficult to implement. We demonstrate that graphene can significantly alter the morphology of titanium silicalite (TS-1) particles, in particular being able to reduce their dimensions from several hundreds to less than 10 nm. Through electron microscopy and molecular mechanics simulations we propose a mechanism for this change based on the preferential interaction of specific TS-1 surfaces with benzyl-alcohol-mediated graphene. These findings suggest a facile new means of controlling the zeolite morphology and thereby also further demonstrate the potential of graphene in hybrid materials. Moreover, the generality of the mechanism points the way to a new avenue of research in using two-dimensional materials to engineer functional inorganic crystals. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00320a

Gebhardt, Paul; Pattinson, Sebastian W.; Ren, Zhibin; Cooke, David J.; Elliott, James A.; Eder, Dominik

2014-06-01

152

Natural zeolite reactivity towards ozone: the role of compensating cations.  

PubMed

Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal. PMID:22633878

Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A

2012-08-15

153

Synthesis of Dihydropyrimidinones Using Large Pore Zeolites  

Microsoft Academic Search

\\u000a Abstract  A series of dihydropyrimidin-2(1H)-one (DHPM) belongs to one of the important class of therapeutic and pharmacological active compound, were synthesized through\\u000a the multicomponent reactions (MCRs) of aldehydes, ethyl acetoacetate and urea, followed by the heterogeneous catalyzed Biginelli\\u000a reaction. In the present endeavour, medium (ZSM-5) and large pore zeolites (Y, BEA and MOR) as well as dealuminated zeolites\\u000a BEA, were studied

Sunil R. Mistry; Rikesh S. Joshi; Suban K. Sahoo; Kalpana C. Maheria

154

Fly ash zeolite catalyst support for Fischer-Tropsch synthesis  

NASA Astrophysics Data System (ADS)

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

Campen, Adam

155

Copper peroxide  

NASA Technical Reports Server (NTRS)

A number of oxidizing agents, including chlorine, bromine, ozone and other peroxides, were allowed to act on copper solutions with the intention of forming copper peroxide. The only successful agent appears to be hydrogen peroxide. It must be used in a neutral 50 to 30 percent solution at a temperature near zero. Other methods described in the literature apparently do not work. The excess of hydrogen must be quickly sucked out of the brown precipitate, which it is best to wash with alcohol and ether. The product, crystalline under a microscope, can be analyzed only approximately. It approaches the formula CuO2H2O. In alkaline solution it appears to act catalytically in causing the decomposition of other peroxides, so that Na2O2 cannot be used to prepare it. On the addition of acids the H2O2 is regenerated. The dry substance decomposes much more slowly than the moist but is not very stable.

Moser, L.

1988-01-01

156

Process optimization studies of structured Cu–ZSM-5 zeolite catalyst for the removal of NO using design of experiments (DOE)  

Microsoft Academic Search

There has been growing interest in structured catalytic reactors because of their several advantages over conventional fixed-bed catalytic reactor. The structured bed having open macrostructure allows high flow rates with a low-pressure drop. In the present study, the structured catalyst made of ZSM-5 zeolite coatings on stainless steel wire mesh with copper being incorporated in the ZSM-5 was used. The

Khoo Daw Deeng; Abdul Rahman Mohamed; Subhash Bhatia

2004-01-01

157

COPPER AND BRAIN FUNCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increasing evidence shows that brain development and function are impaired when the brain is deprived of copper either through dietary copper deficiency or through genetic defects in copper transport. A number of copper-dependent enzymes whose activities are lowered by copper deprivation form the ba...

158

Silver clusters and chemistry in zeolites  

SciTech Connect

The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

Sun, T.; Seff, K. (Univ. of Hawaii, Honolulu, HI (United States). Dept. of Chemistry)

1994-06-01

159

Multicomponent liquid ion exchange with chabazite zeolites  

SciTech Connect

In spite of the increasing commercial use of zeolites for binary and multicomponent sorption, the understanding of the basic mass-transfer processes associated with multicomponent zeolite ion-exchange systems is quite limited. This study was undertaken to evaluate Na-Ca-Mg-Cs-Sr ion exchange from an aqueous solution using a chabazite zeolite. Mass-transfer coefficients and equilibrium equations were determined from experimental batch-reactor data for single and multicomponent systems. The Langmuir isotherm was used to represent the equilibrium relationship for binary systems, and a modified Dubinin-Polyani model was used for the multicomponent systems. The experimental data indicate that diffusion through the microporous zeolite crystals is the primary diffusional resistance. Macropore diffusion also significantly contributes to the mass-transfer resistance. Various mass-transfer models were compared to the experimental data to determine mass-transfer coefficients. Effective diffusivities were obtained which accurately predicted experimental data using a variety of models. Only the model which accounts for micropore and macropore diffusion occurring in series accurately predicted multicomponent data using single-component diffusivities. Liquid and surface diffusion both contribute to macropore diffusion. Surface and micropore diffusivities were determined to be concentration dependent.

Robinson, S.M.; Arnold, W.D. Jr.; Byers, C.W.

1993-10-01

160

Dispersion enhanced metal/zeolite catalysts  

DOEpatents

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

Sachtler, Wolfgang M. H. (Evanston, IL); Tzou, Ming-Shin (Evanston, IL); Jiang, Hui-Jong (Evanston, IL)

1987-01-01

161

Dispersion enhanced metal/zeolite catalysts  

DOEpatents

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

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

1987-03-31

162

Reactions of cyclopropane over zeolite catalysts  

SciTech Connect

The reaction of cyclopropane on NaY, CaNaY, and NaHY zeolites yielded isobutane, 2-methylbutene, propane, isobutene, 2-methylbutane, 2-methylpentane, and heptanes among the minor products, probably as a result of complex oligomerization, isomerization, and cracking processes of a propylene intermediate.

Kiricsi, I.; Hannus, I.; Varca, K.; Fejes, P.

1980-06-01

163

Zeolite 5A Catalyzed Etherification of Diphenylmethanol  

ERIC Educational Resources Information Center

An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

2009-01-01

164

Conversion of Ethanol to Hydrocarbons on Hierarchical HZSM-5 Zeolites  

SciTech Connect

This study reports synthesis, characterization, and catalytic activity of the nano-size hierarchical HZSM-5 zeolite with high mesoporosity produced via a solvent evaporation procedure. Further, this study compares hierarchical zeolites with conventional HZSM-5 zeolite with similar Si/Al ratios for the ethanol-to-hydrocarbon conversion process. The catalytic performance of the hierarchical and conventional zeolites was evaluated using a fixed-bed reactor at 360 °C, 300 psig, and a weight hourly space velocity of 7.9 h-1. For the low Si/Al ratio zeolite (~40), the catalytic life-time for the hierarchical HZSM-5 was approximately 2 times greater than the conventional HZSM-5 despite its coking amount deposited 1.6 times higher than conventional HZSM-5. For the high Si/Al ratio zeolite (~140), the catalytic life-time for the hierarchical zeolite was approximately 5 times greater than the conventional zeolite and the amount of coking deposited was 2.1 times higher. Correlation was observed between catalyst life time, porosity, and the crystal size of the zeolite. The nano-size hierarchical HZSM-5 zeolites containing mesoporosity demonstrated improved catalyst life-time compared to the conventional catalyst due to faster removal of products, shorter diffusion path length, and the migration of the coke deposits to the external surface from the pore structure.

Ramasamy, Karthikeyan K.; Zhang, He; Sun, Junming; Wang, Yong

2014-12-15

165

UTILITY OF ZEOLITES IN REMOVAL OF INORGANIC AND ORGANIC WATER POLLUTANTS  

EPA Science Inventory

Zeolites are well known for their ion exchange, adsorption and acid catalysis properties. Different inorganic and organic pollutants have been removed from water at room temperature using various zeolites. Synthetic zeolite Faujasite Y has been used to remove inorganic pollutants...

166

Lab Tracker and Copper Calculator  

MedlinePLUS

... Lab Tracker and Copper Calculator Serum Copper (mcg/dl) Ceruloplasmin (mg/dl) Non-Ceruloplasmin Copper Serum Copper (micromoles/liter) Ceruloplasmin ( ... Copper per 24 hours (micrograms) Copper concentration (mcg/dl) Volume (liters) Copper per 24 hours (micrograms) Copper ...

167

CO2 SEPARATIONS USING ZEOLITE MEMBRANES  

SciTech Connect

Zeolite and other inorganic molecular sieve membranes have shown potential for separations based on molecular size and shape because of their small pore sized, typically less than 1 nm, and their narrow pore size distribution. The high thermal and chemical stability of these inorganic crystals make them ideal materials for use in high temperature applications such as catalytic membrane reactors. Most of the progress with zeolite membranes has been with MFI zeolites prepared on porous disks and tubes. The MFI zeolite is a medium pore size structure having nearly circular pores with diameters between .53 and .56 nm. Separation experiments through MFI membranes indicate that competitive adsorption separates light gas mixtures. Light gas selectivities are typically small, however, owing to small differences in adsorption strengths and their small sizes relative to the MFI pore opening. Furthermore, competitive adsorption does not work well at high temperature where zeolite membranes are stable and have potential application. Separation by differences in size has a greater potential to work at high temperature than competitive adsorption, but pores smaller than those in MFI zeolites are required. Therefore, some studies focused on the synthesis of a small, 8-membered-pore structures such as zeolite A (0.41-nm pore diameter) and SAPO-34, a chabazite (about .4-nm pore diameter with about 1.4 nm cages) analog. The small pore size of the zeolite A and SAPO-34 structures made the separation of smaller molecules by differences in size possible. Zeolite MFI and SAPO-34 membranes were prepared on the inside surface of porous alumina tubes by hydrothermal synthesis, and single gas and binary mixture permeances were measured to characterize the membrane's performance. A mathematical diffusion model was developed to determine the relative quantities of zeolite and non-zeolite pores in different membranes by modeling the permeation date of CO{sub 2}. This model expresses the total flux through the membrane as the sum of surface diffusion through zeolite pores and viscous flow and Knudsen diffusion through non-zeolite pores. As predicted by the model, the permeance of CO{sub 2} decrease with increasing pressure at constant pressure drop for membranes with few non-zeolite pores, but the permeance increased through viscous flow pores and was constant through pores allowing Knudsen diffusion. Membranes having more non-zeolite pores had lower CO{sub 2}/CH{sub 4} selectivities. The SAPO-34 membranes were characterized for light gas separation applications, and the separation mechanisms were identified. Single gas permeances of CO{sub 2}, N{sub 2}, and CH{sub 4} decreased with increasing kinetic diameter. For the best membrane at 300K, the He and H{sub 2} permeances were less than that of CO{sub 2}, because He, H{sub 2} and CO{sub 2} were small compared to the SAPO-34 pore, and differences in the heat of adsorption determined the permeance order. The small component permeated the fastest in CO{sub 2}/CH{sub 4}, CO{sub 2}/N{sub 2}, N{sub 2}/CH{sub 4}, H{sub 2}/CH{sub 4}, and H{sub 2}/N{sub 2} mixtures between 300 and 470 K. For H{sub 2}/CO{sub 2} mixtures, which were separated by competitive adsorption at room temperature, the larger component permeated faster below 400K. The room temperature CO{sub 2}/CH{sub 4} selectivity was 36 and decreased with temperature. The H{sub 2}/CH{sub 4} mixture selectivity was 8 and constant with temperature up to 480 K. Calcination, slow temperature cycles, and exposure to water vapor had no permanent effect on membrane performance, but temperature changes of approximately 30 K/min decreased the membrane's effectiveness. The effects of humidity on gas permeation were studied with SAPO-34 membranes of different qualities. Membranes with high CO{sub 2}/CH{sub 4} selectivities (greater than 20) were stable in water vapor under controlled conditions, but degradation was seen for some membranes. The degradation opened non-SAPO-34 pores that were larger than SAPO-34 pores as shown by the IC{sub 4}H{sub 10} permeance, C

Richard D. Noble; John L. Falconer

2001-06-30

168

Synthesis strategies in the search for hierarchical zeolites.  

PubMed

Great interest has arisen in the past years in the development of hierarchical zeolites, having at least two levels of porosities. Hierarchical zeolites show an enhanced accessibility, leading to improved catalytic activity in reactions suffering from steric and/or diffusional limitations. Moreover, the secondary porosity offers an ideal space for the deposition of additional active phases and for functionalization with organic moieties. However, the secondary surface represents a discontinuity of the crystalline framework, with a low connectivity and a high concentration of silanols. Consequently, hierarchical zeolites exhibit a less "zeolitic behaviour" than conventional ones in terms of acidity, hydrophobic/hydrophilic character, confinement effects, shape-selectivity and hydrothermal stability. Nevertheless, this secondary surface is far from being amorphous, which provides hierarchical zeolites with a set of novel features. A wide variety of innovative strategies have been developed for generating a secondary porosity in zeolites. In the present review, the different synthetic routes leading to hierarchical zeolites have been classified into five categories: removal of framework atoms, surfactant-assisted procedures, hard-templating, zeolitization of preformed solids and organosilane-based methods. Significant advances have been achieved recently in several of these alternatives. These include desilication, due to its versatility, dual templating with polyquaternary ammonium surfactants and framework reorganization by treatment with surfactant-containing basic solutions. In the last two cases, the materials so prepared show both mesoscopic ordering and zeolitic lattice planes. Likewise, interesting results have been obtained with the incorporation of different types of organosilanes into the zeolite crystallization gels, taking advantage of their high affinity for silicate and aluminosilicate species. Crystallization of organofunctionalized species favours the formation of organic-inorganic composites that, upon calcination, are transformed into hierarchical zeolites. However, in spite of this impressive progress in novel strategies for the preparation of hierarchical zeolites, significant challenges are still ahead. The overall one is the development of methods that are versatile in terms of zeolite structures and compositions, capable of tuning the secondary porosity properties, and being scaled up in a cost-effective way. Recent works have demonstrated that it is possible to scale-up easily the synthesis of hierarchical zeolites by desilication. Economic aspects may become a significant bottleneck for the commercial application of hierarchical zeolites since most of the synthesis strategies so far developed imply the use of more expensive procedures and reagents compared to conventional zeolites. Nevertheless, the use of hierarchical zeolites as efficient catalysts for the production of high value-added compounds could greatly compensate these increased manufacturing costs. PMID:23138888

Serrano, D P; Escola, J M; Pizarro, P

2013-05-01

169

Fabrication of 3D copper oxide structure by holographic lithography for photoelectrochemical electrodes.  

PubMed

We fabricated three-dimensional copper oxide structure by holographic lithography and electroless deposition. A five-beam interference pattern defined a woodpile structure of SU-8. The surface modification of SU-8 structure was achieved by multilayer coating of polyelectrolyte, which is critical for activating the surface for the reduction of copper. Copper was deposited onto the surface of the structure by electroless deposition, and subsequent calcinations removed the SU-8 structure and simultaneously oxidized the copper into copper oxide. The porous copper oxide structure was used as a photoelectrochemical electrode. Because of the highly porous structure, our structure showed higher photocurrent efficiency. PMID:21062017

Jin, Woo-Min; Kang, Ji-Hwan; Moon, Jun Hyuk

2010-11-01

170

Seeding of Porous Alumina Substrate with MFI Zeolite Nanocrystals using Spin-coating Technique  

E-print Network

Zeolite membranes offer a great potential for applications in many challenging separation processes. Controlled thickness of zeolite membrane allows high flux and excellent selectivity commercially available; producing ...

Baroud, T.

171

Atomic sites and stability of Cs+ captured within zeolitic nanocavities.  

PubMed

Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as (137)Cs(+) from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical application, there are still open questions, at the atomic-level, on the physical and chemical origins of selective ion-exchange abilities of different cations and detailed atomic structures of exchanged cations inside the nanoscale cavities of zeolites. Here, the precise locations of Cs(+) ions captured within A-type zeolite were analyzed using high-resolution electron microscopy. Together with theoretical calculations, the stable positions of absorbed Cs(+) ions in the nanocavities are identified, and the bonding environment within the zeolitic framework is revealed to be a key factor that influences the locations of absorbed cations. PMID:23949184

Yoshida, Kaname; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Nakahira, Atsushi; Kurata, Hiroki; Ikuhara, Yumi H; Sasaki, Yukichi

2013-01-01

172

Preparation of Robust, Thin Zeolite Membrane Sheet for Molecular Separation  

SciTech Connect

This paper reports a feasibility study on the preparation of zeolite membrane films on a thin, porous metal support sheet (50-{micro}m thick). Zeolite sodium A (NaA) and silicalite zeolite frameworks are chosen to represent synthesis of respective hydrophilic-type and hydrophobic-type zeolite membranes on this new support. It is found that a dense, continuous inter-grown zeolite crystal layer at a thickness less than 2 {micro}m can be directly deposited on such a support by using direct and secondary growth techniques. The resulting membrane shows excellent adhesion on the metal sheet. Molecular-sieving functions of the prepared membranes are characterized with ethanol/water separation, CO2 separation, and air dehumidification. The results show great potential to make flexible metal-foil-like zeolite membranes for a range of energy conversion and environmental applications.

Liu, Wei; Zhang, Jian; Canfield, Nathan L.; Saraf, Laxmikant V.

2011-10-19

173

Conversion of rice husk ash to zeolite beta.  

PubMed

White rice husk ash (RHA), an agriculture waste containing crystalline tridymite and alpha-cristobalite, was used as a silica source for zeolite Beta synthesis. The crystallization of zeolite Beta from RHA at 150 degrees C in the presence of tetraethylammonium hydroxide was monitored by XRD, FTIR and (29)Si MAS NMR techniques. It was found that zeolite Beta started to form after 12h and the complete crystallization of zeolite Beta phase was achieved after 2d. XRD, (29)Si MAS NMR and solid yield studies indicate that the transformation mechanism of silica present in RHA to zeolite Beta involves dissolution of the ash, formation of an amorphous aluminosilicate after 6h of crystallization, followed by dissolution in the mother liquor and final transformation to pure zeolite Beta crystals. PMID:16274981

Prasetyoko, Didik; Ramli, Zainab; Endud, Salasiah; Hamdan, Halimaton; Sulikowski, Bogdan

2006-01-01

174

Advanced zeolites used in FCC catalysts boost motor octane number  

SciTech Connect

Fluid catalytic cracking catalysts that contain an advanced zeolite called LZ-210, have been shown, by commercial trials, to increase the motor octane number (MON) of the FCC gasoline produced. The zeolite crystal utilizes lower unit cell size, lower sodium in the zeolite, less alumina debris in the zeolite structure, and silica reinsertion into the zeolite structure to accomplish the MON increase. Data from commercial trials are presented to support the MON increases, along with some explanations of how the advanced zeolite accomplishes them. A strong gasoline market and the removal of lead have combined to place a premium on clear gasoline octanes. Because gasoline from fluid catalytic cracking units is the largest segment of the refinery pool (up to 40%), its octane numbers are particularly important. Traditional emphasis has been on the research octance number (RON) but motor octanes frequently limit the blending process.

Letzsch, W.S.; Magee, J.S.; Upson, L.L.; Valeri, F. (Katalistiks International, Baltimore, MD (US))

1988-10-31

175

Changes in copper concentrations affect the protein levels but not the mRNA levels of copper chaperones in human umbilical vein endothelial cells.  

PubMed

Copper chaperones are critical regulators of intracellular copper metabolism and distribution. The present study was undertaken to investigate the effects of changes in copper concentrations on the abundance of copper chaperones. Human umbilical vein endothelial cells (HUVECs) were treated with siRNA targeting copper transporter 1 (CTR1) or tetraethylenepentamine (TEPA) to decrease, or with copper sulfide to increase, intracellular copper concentrations, assayed using an atomic absorption spectrophotometer. Western blot analyses showed that CTR1 silencing or TEPA treatment increased the protein levels of copper chaperone ATOX1 and copper chaperone for superoxide dismutase 1 (CCS-1), but decreased copper chaperone for cytochrome c oxidase (COX17). In contrast, copper supplementation decreased the protein levels of ATOX1 and CCS-1 and increased COX17. Real-time RT-PCR analyses found no difference in the mRNA levels of the copper chaperones examined under the conditions defined above. This study thus demonstrated that changes in copper concentrations alter the protein levels, but not the mRNA levels, of copper chaperones, suggesting a role of copper in the post-translational modification of these proteins. PMID:24343031

Dong, Daoyin; Xu, Xinhua; Yin, Wen; Kang, Y James

2014-03-01

176

Chemical Interactions in Multimetal/Zeolite Catalysts  

SciTech Connect

This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that the PI is also actively engaged in a project on the reduction of nitrogen oxides, sponsored by EMSI program of the National Science Foundation and the US Department of Energy, Office of Science. This combination created a unique opportunity to test and analyze catalysts for the one step oxidation of benzene to phenol and compare them with catalysts for the reduction of nitrogen oxides, using hydrocarbons as the reductant. In both projects catalysts have been used which contain Fe ions or oxo-ions in the cavities the zeolite MFI, often called ZSM-5. With Fe as the TM-element and MFI as the host zeolite we found that catalysts with high Fe content, prepared by technique (2) were optimal for the De-NO{sub x} reaction, but extremely unselective for benzene oxidation to phenol. Conversely, the catalysts prepared with (4) had the highest turnover frequency for benzene oxidation, but performed very poorly for NO{sub x} reduction with so-butane. In fact the Fe concentration in the former catalysts were so low that it was necessary to design a special experimental program for the sole purpose of showing that it is really the Fe which catalyzes the benzene oxidation, not some acid center as has been proposed by other authors. For this purpose we used hydrogen sulfide to selectively poison the Fe sites, without deactivating the acidic sites. In addition we could show that the hydrothermal treatment of catalysts prepared by technique (4) is essential to transform iron ions in the zeolite lattice to ''ex lattice ions'' in guest positions. That line of the work required very careful experimentation, because a hydrothermal treatment of a zeolite containing Fe ions in its cavities can also lead to agglomeration of such ions to nano-particles of iron oxide which lowers the selectivity for the desired formation of phenol. This part of the program showed convincingly that indeed Fe is responsible for the benzene oxidation catalysis. The results and conclusion of this work, including the comparison of different catalysts, was published in a number of papers in the scientific literature, listed in the attached list. In these papers also our analysis of the reaction orders and the possible mechanism of the used test reaction are given.

Sachtler, Wolfgang M. H.

2004-04-16

177

Role of copper transporters in copper homeostasis.  

PubMed

Copper is a redox active metal that is essential for biological function. Copper is potentially toxic; thus, its homeostasis is carefully regulated through a system of protein transporters. Copper is taken up across the lumen surface of the small intestinal microvilli as cuprous ion by Ctr1. Cupric ion may also be taken up, but those processes are less well understood. Within the cell, intestinal as well as others, copper is escorted to specific compartments by metallochaperones. One, CCS, donates copper to superoxide dismutase. Another, COX17, delivers copper to additional chaperones within the mitochondria for synthesis of cytochrome c oxidase. A third chaperone, Atox1, delivers copper to the secretory pathway by docking with 2 P-type ATPases. One, ATP7A, is the protein nonfunctional in Menkes disease. This protein is required for cuproenzyme biosynthesis, and in the enterocyte it is required for copper efflux to portal blood. The second, ATP7B, predominantly expressed in liver, is required for copper metallation of ceruloplasmin and biliary copper excretion. Mutations in ATP7B lead to Wilson disease. Additional intracellular hepatic copper-binding proteins COMMD1 (copper metabolism MURR1 domain) and XIAP (X-linked inhibitor of apoptosis protein) may also be required for excretion. Other proteins involved in copper homeostasis may include metallothionein and amyloid precursor protein. Plasma protein transport of copper from the intestine to liver and in systemic circulation probably includes both albumin and alpha2-macroglobulin. Changes in the expression of copper "transporters" may be useful to monitor copper status of humans, provided a suitable cell type can be sampled. PMID:18779302

Prohaska, Joseph R

2008-09-01

178

Transesterification of soybean oil with zeolite and metal catalysts  

Microsoft Academic Search

Transesterification of soybean oil with methanol was carried out at 60, 120, and 150°C in the presence of a series NaX faujasite zeolite, ETS-10 zeolite, and metal catalysts. The stock zeolites were exchanged with potassium and cesium; NaX containing occluded sodium oxide (NaOx\\/NaX) and occluded sodium azide (NaOx\\/NaX*). The catalysts were calcined at 500°C prior to use in order to

Galen J. Suppes; Mohanprasad A. Dasari; Eric J. Doskocil; Pratik J. Mankidy; Michael J. Goff

2004-01-01

179

Large zeolites - Why and how to grow in space  

NASA Technical Reports Server (NTRS)

The growth of zeolite crystals which are considered to be the most valuable catalytic and adsorbent materials of the chemical processing industry are discussed. It is proposed to use triethanolamine as a nucleation control agent to control the time release of Al in a zeolite A solution and to increase the average and maximum crystal size by 25-50 times. Large zeolites could be utilized to make membranes for reactors/separators which will substantially increase their efficiency.

Sacco, Albert, Jr.

1991-01-01

180

Method for the recovery of silver from silver zeolite  

DOEpatents

High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

Reimann, George A. (Idaho Falls, ID)

1986-01-01

181

Zeolites are effective ROS-scavengers in vitro.  

PubMed

We report on the use of zeolites to limit the effects of reactive oxygen species (ROS) on human albumin under in vitro conditions. Zeolites of different structure type, channel size, channel polarity, and charge-compensating cation were screened for the elimination of ROS, notably HO(·), resulting from the Fenton reaction. A test based on ischemia-modified albumin (IMA) was used as a marker to monitor the activity of HO(·) after co-exposure of human serum to these zeolites. Two commercial zeolites, faujasite (FAU 13×, channel opening 0.74×0.74 nm with Na(+) as charge-compensating cation) and ferrierite (FER, channel opening 0.54×0.42 nm with H(+) as charge-compensating cation), were found to reduce IMA formation by more than 65% due to removal of HO(·) relative to reference values. It was established that partial ion exchange of the zeolites' respective charge-compensating cation vs. Fe(3+) implicated in the Fenton reaction plays a major role in HO(·) deactivation process. Moreover, our results show that no saturation of the respective zeolite active sites occurred. This is possible only when ROS are actively converted to water molecules within the zeolite void system, which generates H(+) ion transport. Because zeolites cannot be administered in blood, their use in medicine should be limited to extra corporeal circuits. Zeolites could be of use during cardiopulmonary bypass or hemodialysis procedures. PMID:21679693

Pellegrino, Perrine; Mallet, Bernard; Delliaux, Stéphane; Jammes, Yves; Guieu, Regis; Schäf, Oliver

2011-07-01

182

Method for the recovery of silver from silver zeolite  

DOEpatents

High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

Reimann, G.A.

1985-03-05

183

Zeolite Crystal Growth in Microgravity and on Earth  

NASA Technical Reports Server (NTRS)

The Center for Advanced Microgravity Materials Processing (CAMMP), a NASA-sponsored Research Partnership Center, is working to improve zeolite materials for storing hydrogen fuel. CAMMP is also applying zeolites to detergents, optical cables, gas and vapor detection for environmental monitoring and control, and chemical production techniques that significantly reduce by-products that are hazardous to the environment. Shown here are zeolite crystals (top) grown in a ground control experiment and grown in microgravity on the USML-2 mission (bottom). Zeolite experiments have also been conducted aboard the International Space Station.

2003-01-01

184

COPPER CORROSION RESEARCH UPDATE  

EPA Science Inventory

Copper release and corrosion related issues continue to be important to many water systems. The objective of this presentation is to discuss the current state of copper research at the USEPA. Specifically, the role of aging on copper release, use of phosphates for copper corrosio...

185

Raman spectra of zeolites exchanged with uranyl(VI) cations—II. Zeolite X  

NASA Astrophysics Data System (ADS)

The formation of hydrolysed uranyl(VI) species in UO 2X zeolites prepared by various methods has been investigated by Raman spectroscopy. Ion-exchange in aqueous (pH>3) and non-aqueous (anhydrous methanol and uranyl nitrate melts) media resulted in the formation of hydroxy-bridged complexes such as [(UO 2) 3(OH) 4] 2+, [(UO 2) 3(OH) 5] +, and [(UO 2) 4(OH) 7] +. Ion-exchange in more acidic media (initial pH < 3) was accompanied by the formation of a disordered phase incorporating UO 3, following extensive collapse of the zeolite framework structure. Cation speciation in the UO 2X system is compared to that in UO 2Y zeolites.

Bartlett, John R.; Cooney, Ralph P.

1989-01-01

186

Copper and Copper Proteins in Parkinson's Disease  

PubMed Central

Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology. PMID:24672633

Rivera-Mancia, Susana; Diaz-Ruiz, Araceli; Tristan-Lopez, Luis; Rios, Camilo

2014-01-01

187

Copper and copper proteins in Parkinson's disease.  

PubMed

Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology. PMID:24672633

Montes, Sergio; Rivera-Mancia, Susana; Diaz-Ruiz, Araceli; Tristan-Lopez, Luis; Rios, Camilo

2014-01-01

188

Characterisation and evaluation of hypothetical zeolite frameworks  

Microsoft Academic Search

A series of hypothetical zeolites, derived from the results of tiling theory, has been evaluated using computational chemistry techniques. Simulated heats of formation (i.e. the lattice energy with respect to ?-quartz or ?-berlinite for silica polymorphs and AlPO4 polymorphs, respectively) are used as an initial criterion for the chemical “feasibility” of these structures. This data is further correlated with various

2004-01-01

189

Thermionic emission of alkali ions from zeolites  

Microsoft Academic Search

The thermionic emission of positive alkali ions from zeolites has been investigated in the high-voltage pulsed regime. Current densities of up to 1 A cm-2 have been obtained using 2-mus-long 30-kV pulses. This is about two orders of magnitude larger than currents obtained in the low-voltage dc regime. There are two major reasons for this difference. First, the currents have

A. N. Pargellis; M. Seidl

1978-01-01

190

Sorption properties of EU-1 zeolites  

SciTech Connect

Various features of the sorption of benzene, n-hexane, and cyclohexane, H{sub 2}O, n-butylamine on the protonic forms of EU-1 zeolites of varying Si/Al ratio (SAR = 57.5-262.5) are reported. Equilibrium sorption uptake at P/P{sub 0} = 0.8 and 298 K for benzene (8.50 {plus minus} 0.50 wt %), n-hexane (8.25 {plus minus} 0.20 wt %), and cyclohexane (1.55 {plus minus} 0.25 wt %) was found to be unaffected by varying Si/Al ratio. Equilibrium uptake for water was found to decrease (5.89-3.95%) with the increase in Si/Al ratio, indicating enhanced hydrophobic character of the zeolites on increasing Si/Al ratio. The BET surface area was also found to decrease from 385 to 290 m{sup 2}/g with increasing Si/Al ratio. Sorption isotherms for n-butylamine (n-BA) in the temperature range 298-423 K were found to be of Langmuir type. The number of n-BA molecules sorbed per unit cell of EU-1 zeolites decreases with the increase in Si/Al ratio. n-BA sorption data was satisfactorily represented by Dubinin, BET, and Langmuir isotherm equations.

Rao, G.N.; Joshi, P.N.; Kotasthane, A.N.; Shiralkar, V.P. (National Chemical Lab., Pune (India))

1990-11-15

191

Zeolite thin films: from computer chips to space stations.  

PubMed

Zeolites are a class of crystalline oxides that have uniform and molecular-sized pores (3-12 A in diameter). Although natural zeolites were first discovered in 1756, significant commercial development did not begin until the 1950s when synthetic zeolites with high purity and controlled chemical composition became available. Since then, major commercial applications of zeolites have been limited to catalysis, adsorption, and ion exchange, all using zeolites in powder form. Although researchers have widely investigated zeolite thin films within the last 15 years, most of these studies were motivated by the potential application of these materials as separation membranes and membrane reactors. In the last decade, we have recognized and demonstrated that zeolite thin films can have new, diverse, and economically significant applications that others had not previously considered. In this Account, we highlight our work on the development of zeolite thin films as low-dielectric constant (low-k) insulators for future generation computer chips, environmentally benign corrosion-resistant coatings for aerospace alloys, and hydrophilic and microbiocidal coatings for gravity-independent water separation in space stations. Although these three applications might not seem directly related, they all rely on the ability to fine-tune important macroscopic properties of zeolites by changing their ratio of silicon to aluminum. For example, pure-silica zeolites (PSZs, Si/Al = infinity) are hydrophobic, acid stable, and have no ion exchange capacity, while low-silica zeolites (LSZs, Si/Al < 2) are hydrophilic, acid soluble, and have a high ion exchange capacity. These new thin films also take advantage of some unique properties of zeolites that have not been exploited before, such as a higher elastic modulus, hardness, and heat conductivity than those of amorphous porous silicas, and microbiocidal capabilities derived from their ion exchange capacities. Finally, we briefly discuss our more recent work on polycrystalline zeolite thin films as promising biocompatible coatings and environmentally benign wear-resistant and antifouling coatings. When zeolites are incorporated into polymer thin films in the form of nanocrystals, we also show that the resultant composite membranes can significantly improve the performance of reverse osmosis membranes for sea water desalination and proton exchange membrane fuel cells. These diverse applications of zeolites have the potential to initiate new industries while revolutionizing existing ones with a potential economic impact that could extend into the hundreds of billions of dollars. We have licensed several of these inventions to companies with millions of dollars invested in their commercial development. We expect that other related technologies will be licensed in the near future. PMID:20158246

Lew, Christopher M; Cai, Rui; Yan, Yushan

2010-02-16

192

In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites  

SciTech Connect

A custom waveguide apparatus is constructed to study the microwave synthesis of zeolites by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WR-284 waveguide is used to heat precursor solutions using microwaves at a frequency of 2.45 GHz. The reaction vessels are designed to include sections of thin-walled glass, which permit X-rays to pass through the precursor solutions with minimal attenuation. Slots were machined into the waveguide to provide windows for X-ray energy to enter and scatter from solutions during microwave heating. The synthesis of zeolites with conventional heating is also studied using X-ray scattering in the same reactor. SAXS studies show that the crystallization of beta zeolite and NaY zeolite is preceded by a reorganization of nanosized particles in their precursor solutions or gels. The evolution of these particles during the nucleation and crystallization stages of zeolite formation depends on the properties of the precursor solution. The synthesis of NaA and NaX zeolites and sodalite from a single zeolite precursor is studied by microwave and conventional heating. Microwave heating shifts the selectivity of this synthesis in favor of NaA and NaX over sodalite; conventional heating leads to the formation of sodalite for synthesis from the same precursor. The use of microwave heating also led to a more rapid onset of NaA zeolite product crystallization compared to conventional heating. Pulsed and continuous microwave heating are compared for zeolite synthesis. The resulting rates of formation of the zeolite products, and the relative amounts of the products determined from the WAXS spectra, are similar when either pulsed or continuous microwave heating is applied in the reactor while maintaining the same synthesis temperature. The consequences of these results in terms of zeolite synthesis are discussed.

Panzarella,B.; Tompsett, G.; Conner, W.; Jones, K.

2007-01-01

193

Crystal engineering of zeolites with graphene Paul Gebhardt,a  

E-print Network

of controlling the zeolite morphology and thereby also further demonstrate the potential of graphene in hybrid Specically, the hybridization of titanium-silicalite (TS-1) with 5­ 10 wt% of graphene (produced via arcCrystal engineering of zeolites with graphene Paul Gebhardt,a Sebastian W. Pattinson,b Zhibin Ren

Elliott, James

194

Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen  

DOEpatents

A process is described for selective thermal oxidation or photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts. 19 figs.

Frei, H.; Blatter, F.; Sun, H.

1999-06-22

195

NO2 disproportionation for the IR characterisation of basic zeolites.  

PubMed

NO2 disproportionation on alkaline zeolites is used to generate nitrosonium (NO+) and nitrate ions on the surface, and the infrared vibrations observed are very sensitive to the cation chemical hardness and to the basicity of zeolitic oxygen atoms. PMID:15719112

Marie, Olivier; Malicki, Nicolas; Pommier, Catherine; Massiani, Pascale; Vos, Ann; Schoonheydt, Robert; Geerlings, Paul; Henriques, Carlos; Thibault-Starzyk, Fréderic

2005-02-28

196

Zeolite films prepared via the Langmuir–Blodgett technique  

Microsoft Academic Search

Micrometer sized zeolite particles were found to form relatively stable particle monolayers at the air–water interface when spread from a chloroform dispersion. For these layers compression isotherms were recorded. The presence of polyelectrolytes in the aqueous subphase was found to have a significant influence on the compression behaviour of the films and on the degree of orientation of the zeolite

K Morawetz; J Reiche; H Kamusewitz; H Kosmella; R Ries; M Noack; L Brehmer

2002-01-01

197

CATION CONTROLLED SINGLET OXYGEN MEDIATED OXIDATION OF OLEFINS WITHIN ZEOLITES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oxidation of trialkyl olefins has been performed within zeolites employing thionin as the singlet oxygen sensitizer. Unusual selectivity in favor of secondary hydroperoxides is observed within zeolites. In light of the fact that in solution such a selectivity is never observed the selectivity report...

198

Zeolites in the Pine Ridge Indian Reservation, South Dakota  

USGS Publications Warehouse

Zeolites of possible commercial value occur in the Brule Formation of Oligocene age and the Sharps Formation (Harksen, 1961) of Miocene age which crop out in a wide area in the northern part of the Pine Ridge Indian Reservation. The thickness of the zeolite-bearing Interval and the extent of areas within the Interval which contain significant amounts of zeolites are far greater than was expected prior to this investigation. The shape of the zeolite-bearing Interval is tabular and the dimensions of Its exposure are roughly 10 ml x 200 mi x 150 ft (16 km x 160 km x 45 m) thick. Within the study area, there are tracts in which the zeolite resource potential is significant (see pl. 2). This report is intended to inform the Oglala Sioux Tribe of some of the most promising zeolite occurrences. Initial steps can then be taken by the Tribe toward possible development of the resources, should they wish to do so. The data contained herein identify areas of high zeolite potential, but are not adequate to establish economic value for the deposits. If development is recommended by the tribal government, we suggest that the tribal government contact companies involved in research and production of natural zeolites and provide them with the data in this report.

Raymond, William H.; Bush, Alfred L.; Gude, Arthur J., 3rd

1982-01-01

199

Synthesis of zeolites from coal fly ash: an overview  

Microsoft Academic Search

Coal combustion by-products production in USA and EU is estimated in around 115 million tons per year. A large portion of this production is accounted for the coal fly ash (CFA). Cement and concrete manufacturing consumes most of the CFA produced. Zeolite synthesized from CFA is a minor but interesting product, with high environmental applications. Zeolites may be easily obtained

X Querol; N Moreno; J. C Umaña; A Alastuey; E Hernández; A López-Soler; F Plana

2002-01-01

200

FUNDAMENTALS AND APPLICATIONS OF PERVAPORATION THROUGH ZEOLITE MEMBRANES  

EPA Science Inventory

Zeolite membranes are well suited for separating liquid-phase mixtures by pervaporation because of their molecular-sized pores and their hydrophilic/hydrophobic nature, and the first commercial application of zeolite membranes has been for dehydrating organics [1]. Because of ...

201

Crewmember working on the mid deck Zeolite Crystal Growth experiment.  

NASA Technical Reports Server (NTRS)

View showing Payload Specialist Bonnie Dunbar, in the mid deck, conducting the Zeolite Crystal Growth (ZCG) Experiment in the mid deck stowage locker work area. View shows assembly of zeolite sample in the metal autoclave cylinders prior to insertion into the furnace.

1992-01-01

202

Transport properties of alkanes through ceramic thin zeolite MFI membranes  

Microsoft Academic Search

Polycrystalline randomly oriented defect free zeolite layers on porous ?-Al2O3 supports are prepared with a thickness of less than 5 ?m by in situ crystallisation of silicalite-1. The flux of alkanes is a function of the sorption and intracrystalline diffusion. In mixtures of strongly and weakly adsorbing gases and a high loadings of the strongly adsorbing molecule in the zeolite

Z. A. E. P. Vroon; K. Keizer; M. J. Gilde; H. Verweij; A. J. Burggraaf

1996-01-01

203

Selective thermal oxidation of hydrocarbons in zeolites by oxygen  

DOEpatents

A process for selective thermal oxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls is carried out in solvent free zeolites under dark thermal conditions. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts.

Frei, Heinz (Berkeley, CA); Blatter, Fritz (Basel, CH); Sun, Hai (Saint Charles, MO)

2000-01-01

204

Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen  

DOEpatents

A process for selective thermal oxidation or photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts.

Frei, Heinz (Berkeley, CA); Blatter, Fritz (Basel, CH); Sun, Hai (Saint Charles, MO)

1999-01-01

205

Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen  

DOEpatents

A process for a combined selective thermal oxidation and photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly combined selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts.

Frei, Heinz (Berkeley, CA); Blatter, Fritz (Basel, CH); Sun, Hai (Saint Charles, MO)

2001-01-01

206

A zeolite ion exchange membrane for redox flow batteries.  

PubMed

The zeolite-T membrane was discovered to have high proton permselectivity against vanadium ions and exhibit low electrical resistance in acidic electrolyte solutions because of its enormous proton concentration and small thickness. The zeolite membrane was demonstrated to be an efficient ion exchange membrane in vanadium redox flow batteries. PMID:24396857

Xu, Zhi; Michos, Ioannis; Wang, Xuerui; Yang, Ruidong; Gu, Xuehong; Dong, Junhang

2014-03-01

207

Oxygen transport in zeolite Y measured by quenching of encapsulated tris(bipyridyl)ruthenium  

E-print Network

Oxygen transport in zeolite Y measured by quenching of encapsulated tris(bipyridyl)ruthenium Abstract This study deals with emission quenching of zeolite encapsulated trisbipyridyl ruthenium (II) (Ru the migration of O2 within zeolites using the emis- sion quenching of zeolite encapsulated ruthenium

Dutta, Prabir K.

208

DOI: 10.1002/anie.200702628 Aluminum Siting in Silicon-Rich Zeolite Frameworks: A Combined  

E-print Network

Zeolites DOI: 10.1002/anie.200702628 Aluminum Siting in Silicon-Rich Zeolite Frameworks: A Combined Sauer* Dedicated to Süd-Chemie on the occasion of its 150th anniversary Zeolites are crystalline. Silicon-rich zeolites (Si/Al > 12) such as ZSM-5 (MFI framework) have found particular attention

Sklenak, Stepan

209

Photochemical template removal and spatial patterning of zeolite MFI thin films using UV/ozone treatment  

E-print Network

Photochemical template removal and spatial patterning of zeolite MFI thin films using UV of thin films of microporous or zeolite materials. We prepared thin-films of a high silica zeolite leads to complete removal of template (structure-direc- ting-agent) from zeolite films comparable

Parikh, Atul N.

210

1 Flexibility As an Indicator of Feasibility of Zeolite Frameworks 2 Colby J. Dawson,  

E-print Network

1 Flexibility As an Indicator of Feasibility of Zeolite Frameworks 2 Colby J. Dawson, Vitaliy Kapko two 6 million unique hypothetical zeolite structures. By a simple flexibility calculation, we have 7 feasibility as zeolites. 78 out of 97 officially approved zeolite framework types 9 that occur in the database

Thorpe, Michael

211

Zeolite Nanoslabs? On the TEM and AFM Evidence of Zeosil Nanoslabs  

E-print Network

Zeolite Nanoslabs? On the TEM and AFM Evidence of Zeosil Nanoslabs Present during the Synthesis · nanoslabs · silicates · zeolites The mechanism of formation of syn- thetic zeolite structures has been a subject of many recent investigations.[1­3] One of the commonly studied zeolites is silicalite-1

Kokkoli, Efie

212

Zeolites in Eocene basaltic pillow lavas of the Siletz River Volcanics, Central Coast Range, Oregon.  

USGS Publications Warehouse

Zeolites and associated minerals occur in a tholeiitic basaltic pillow lava sequence. Although the zeolite assemblages are similar to those found in other major zeolite occurrences in basaltic pillow lavas, regional zoning of the zeolite assemblages is not apparent. The formation of the different assemblages is discussed.-D.F.B.

Keith, T.E.C.; Staples, L.W.

1985-01-01

213

Amphiphilic organosilane-directed synthesis of crystalline zeolite with tunable mesoporosity  

Microsoft Academic Search

Zeolites are a family of crystalline aluminosilicate materials widely used as shape-selective catalysts, ion exchange materials, and adsorbents for organic compounds. In the present work, zeolites were synthesized by adding a rationally designed amphiphilic organosilane surfactant to conventional alkaline zeolite synthesis mixtures. The zeolite products were characterized by a complementary combination of X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy

Minkee Choi; Hae Sung Cho; Rajendra Srivastava; Chithravel Venkatesan; Dae-Heung Choi; Ryong Ryoo

2006-01-01

214

A pair distribution function analysis of zeolite beta  

SciTech Connect

We describe the structural refinement of zeolite beta using the local structure obtained with the pair distribution function (PDF) method. A high quality synchrotron and two neutron scattering datasets were obtained on two samples of siliceous zeolite beta. The two polytypes that make up zeolite beta have the same local structure; therefore refinement of the two structures was possible using the same experimental PDF. Optimized structures of polytypes A and B were used to refine the structures using the program PDFfit. Refinements using only the synchrotron or the neutron datasets gave results inconsistent with each other but a cyclic refinement with the two datasets gave a good fit to both PDFs. The results show that the PDF method is a viable technique to analyze the local structure of disordered zeolites. However, given the complexity of most zeolite frameworks, the use of both X-ray and neutron radiation and high-resolution patterns is essential to obtain reliable refinements.

Martinez-Inesta, M.M.; Peral, I.; Proffen, T.; Lobo, R.F. (Delaware); (LANL)

2010-07-20

215

Synthesis and catalytic applications of combined zeolitic/mesoporous materials  

PubMed Central

Summary In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i) the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii) the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials. PMID:22259762

Vernimmen, Jarian; Cool, Pegie

2011-01-01

216

In silico modeling of the Menkes copper-translocating P-type ATPase 3rd metal binding domain predicts that phosphorylation regulates copper-binding.  

PubMed

The Menkes (ATP7A) P(1B)-type ATPase is a transmembrane copper-translocating protein. It contains six similar high-affinity metal-binding domains (MBDs) in the N-terminal cytoplasmic tail that are important for sensing intracellular copper and regulating ATPase function through the transfer of copper between domains. Molecular characterization of copper-binding and transfer is predominantly dependent on NMR structures derived from E. coli expression systems. A limitation of these models is the exclusion of post-translational modifications. We have previously shown that the third copper-binding domain, MBD3, uniquely contains two phosphorylated residues: Thr-327, which is phosphorylated only in the presence of elevated copper; and Ser-339, which is constitutively phosphorylated independent of copper levels. Here, using molecular dynamic simulations, we have incorporated these phosphorylated residues into a model based on the NMR structures of MBD3. Our data suggests that constitutively phosphorylated Ser-339, which is in a loop facing the copper-binding site, may facilitate the copper transfer process by exposing the CxxC copper-binding region of MBD3. Copper-induced phosphorylation of Thr327 is predicted to stabilize this change in conformation. This offers new molecular insights into how cell signaling (phosphorylation) can affect MBD structure and dynamics and how this may in turn affect copper-binding and thus copper-translocation functions of ATP7A. PMID:21258844

Veldhuis, N A; Kuiper, M J; Dobson, R C J; Pearson, R B; Camakaris, J

2011-06-01

217

Charge Transport through a Novel Zeolite Y Membrane by a Self-Exchange Process Hyunjung Lee and Prabir K. Dutta*  

E-print Network

Charge Transport through a Novel Zeolite Y Membrane by a Self-Exchange Process Hyunjung Lee, and relatively pinhole-free zeolitic membranes is described. Nanocrystalline zeolite Y (100-200 nm) is used zeolite membranes toward this end.3 Zeolitic membranes are an active area of research because

Dutta, Prabir K.

218

In-situ x-ray absorption study of copper films in ground watersolutions  

SciTech Connect

This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl{sup -} and HCO{sub 3}{sup -} in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO{sub 3}{sup -} prevented or slowed down the corrosion processes.

Kvashnina, K.O.; Butorin, S.M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

2007-10-29

219

In situ X-ray absorption study of copper films in ground water solutions  

NASA Astrophysics Data System (ADS)

This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl - and HCO3- in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO3- prevented or slowed down the corrosion processes.

Kvashnina, K. O.; Butorin, S. M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

2007-10-01

220

Electrical properties of zeolitized volcaniclastic materials  

NASA Astrophysics Data System (ADS)

The interpretation of electromagnetic anomalies associated with volcanic activity requires a good understanding of two rock properties, the electrical conductivity and the streaming potential coupling coefficient. We measured these properties on 22 consolidated tuff samples containing clays and zeolites typically found in hydrothermal systems or in other areas of high water-rock interactions associated with active volcanic areas. These rocks exhibit unusually high surface conductivity and electrical cementation exponent (2.5-3.3). These features are explained by the highly complex texture of these rocks due to hydration/dissolution processes of the volcanic glass and the formation of clay minerals and zeolites as alteration products. At a pore fluid conductivity of 1.0 +/- 0.2 S m-1, the streaming potential coupling coefficient ranges from -3.55 to -10.7 mV MPa-1. The zeta potential (a key electrochemical property of the pore water/mineral interface) determined from these measurements at T0 = 20°C and pH ~6-7 and corrected for surface conductivity is ~-28 +/- 8 mV at 0.1 M NaCl. Two clay-free samples exhibit a zeta potential ~-16 +/- 5 mV, a value associated with zeolites (clinoptilolite). The temperature dependence of the ? potential is rather strong with ?(T) = ?(T0) [1 + ?? (T - T0)], where ?? ~ 4.2 × 10-2 C-1 in the temperature range 20-60°C. These data are applied to the understanding of large-scale self-potential anomalies located at the ground surface of Miyake-Jima volcano.

Revil, A.; Hermitte, D.; Spangenberg, E.; Cochemé, J. J.

2002-08-01

221

Carbon dioxide sensitivity of zeolitic imidazolate frameworks.  

PubMed

Zeolitic imidazolate frameworks of zinc, cobalt, and cadmium, including the framework ZIF-8 commercially sold as Basolite Z1200, exhibit surprising sensitivity to carbon dioxide under mild conditions. The frameworks chemically react with CO2 in the presence of moisture or liquid water to form carbonates. This effect, which has been previously not reported in metal-organic framework chemistry, provides an explanation for conflicting reports on ZIF-8 stability to water and is of outstanding significance for evaluating the potential applications of metal-organic frameworks, especially for CO2 sequestration. PMID:24889776

Mottillo, Cristina; Friš?i?, Tomislav

2014-07-14

222

Synthesis of zeolite phases from combustion by-products.  

PubMed

Synthesis of zeolites from combustion by-products, including fly ash, bottom ash and rice husk ash, was studied. A molar ratio of SiO2/Al2O3 of 1.5 was used for the syntheses. Refluxing and hydrothermal methods were also used for synthesis for comparison. The reaction temperatures of refluxing and hydrothermal methods were 100 degrees C and 130 degrees C, respectively. Sodalite, phillipsite-K, and zeolite P1 with analcime were obtained when fly ash, bottom ash and rice husk ash were used as starting materials, respectively. With rice husk ash as a starting material, zeolite P1 was produced. This result had advantages over previous studies as there was no prior activation required for the synthesis. The concentrations and types of alkaline used in the synthesis also determined the zeolite type. The different zeolites obtained from three systems were measured for specific surface area and pore size by using BET and Hg-porosimetry, respectively. Ammonium exchange capacities of the synthesised powders containing zeolites, sodalite, zeolite P1 and phillipsite-K were 38.5, 65.0 and 154.7 meq 100 g(-1), respectively. PMID:20421244

Pimraksa, Kedsarin; Chindaprasirt, Prinya; Setthaya, Naruemon

2010-12-01

223

Zeolite Crystal Growth (ZCG) Flight on USML-2  

NASA Technical Reports Server (NTRS)

The extensive use of zeolites and their impact on the world's economy has resulted in many efforts to characterize their structure, and improve the knowledge base for nucleation and growth of these crystals. The zeolite crystal growth (ZCG) experiment on USML-2 aimed to enhance the understanding of nucleation and growth of zeolite crystals, while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, Beta, and Silicalite were grown during the 16 day - USML-2 mission. The solutions where the nucleation event was controlled yielded larger and more uniform crystals of better morphology and purity than their terrestrial/control counterparts. The external surfaces of zeolite A, X, and Silicalite crystals grown in microgravity were smoother (lower surface roughness) than their terrestrial controls. Catalytic studies with zeolite Beta indicate that crystals grown in space exhibit a lower number of Lewis acid sites located in micropores. This suggests fewer structural defects for crystals grown in microgravity. Transmission electron micrographs (TEM) of zeolite Beta crystals also show that crystals grown in microgravity were free of line defects while terrestrial/controls had substantial defects.

Sacco, Albert, Jr.; Bac, Nurcan; Warzywoda, Juliusz; Guray, Ipek; Marceau, Michelle; Sacco, Teran L.; Whalen, Leah M.

1997-01-01

224

ESCA study of rhodium(III)-exchanged zeolite catalysts  

SciTech Connect

Samples of both the often investigated rhodium(III)-zeolite Y and the seldom investigated rhodium(III)-zeolite A were prepared and studied by techniques of electron spectroscopy for chemical analysis (ESCA) both in the originally exchanged condition and after activation to the state in which they would be employed in a catalytic capacity. The ESCA data agree with previously reported ESR data which indicated that Rh(III) may be thermally reduced to Rh metal in the zeolite Y lattice, and that this reduction takes place under much milder conditions than comparable reduction of any other metal previously reported. Contrarily, the ESCA data indicated that Rh(III) was not reduced on the zeolite A, and this lack of reduction may be the explanation for the poor catalytic effect of Rh(III) supported on zeolite A. It is postulated that the metallic Rh produced by the activation of Rh(III)-exchanged zeolite Y and not the Rh(III) species is the true catalytic species in the so-called Rh(III)-zeolite catalysts. (BLM)

Kuznicki, S.M.; Eyring, E.M.

1980-09-01

225

Electron transfer reactions within zeolites: Radical cation from benzonorbornadiene  

SciTech Connect

Zeolites are being used as solid acid catalysts in a number of commercial processes. Occasionally zeolites are also reported to perform as electron transfer agents. Recently, we observed that radical cations of certain olefins and thiophene oligomers can be generated spontaneously within ZSM-5 zeolites. We noticed that these radical cations generated from diphenyl polyenes and thiophene oligomers were remarkably stable (at room temperature) within ZSM-5 and can be characterized spectroscopically at leisure. We have initiated a program on electron transfer processes within large pore zeolites. The basis of this approach is that once a cation radical is generated within a large pore zeolite, it will have sufficient room to undergo a molecular transformation. Our aim is to identify a condition under which electron transfer can be routinely and reliably carried out within large pore zeolites such as faujasites. To our great surprise, when benzonorbornadiene A and a number of olefins were included in divalent cation exchanged faujasites. they were transformed into products very quickly (<15 min). This observation allowed us to explore the use of zeolites as oxidants. Results of our studies on benzonorbornadiene are presented in this communication. 16 refs., 1 fig.

Pitchumani, K.; Ramamurthy, V. [Tulane Univ., New Orleans, LA (United States)] [Tulane Univ., New Orleans, LA (United States); Corbin, D.R. [The Du Pont Company, Wilmington, DE (United States)] [The Du Pont Company, Wilmington, DE (United States)

1996-08-28

226

Demystifying Controlling Copper Corrosion  

EPA Science Inventory

The LCR systematically misses the highest health and corrosion risk sites for copper. Additionally, there are growing concerns for WWTP copper in sludges and discharge levels. There are many corrosion control differences between copper and lead. This talk explains the sometimes c...

227

Copper metabolism of astrocytes  

PubMed Central

This short review will summarize the current knowledge on the uptake, storage, and export of copper ions by astrocytes and will address the potential roles of astrocytes in copper homeostasis in the normal and diseased brain. Astrocytes in culture efficiently accumulate copper by processes that include both the copper transporter Ctr1 and Ctr1-independent mechanisms. Exposure of astrocytes to copper induces an increase in cellular glutathione (GSH) content as well as synthesis of metallothioneins, suggesting that excess of copper is stored as complex with GSH and in metallothioneins. Furthermore, exposure of astrocytes to copper accelerates the release of GSH and glycolytically generated lactate. Astrocytes are able to export copper and express the Menkes protein ATP7A. This protein undergoes reversible, copper-dependent trafficking between the trans-Golgi network and vesicular structures. The ability of astrocytes to efficiently take up, store and export copper suggests that astrocytes play a key role in the supply of neurons with copper and that astrocytes should be considered as target for therapeutic interventions that aim to correct disturbances in brain copper homeostasis. PMID:23503037

Dringen, Ralf; Scheiber, Ivo F.; Mercer, Julian F. B.

2013-01-01

228

Copper metabolism of astrocytes.  

PubMed

This short review will summarize the current knowledge on the uptake, storage, and export of copper ions by astrocytes and will address the potential roles of astrocytes in copper homeostasis in the normal and diseased brain. Astrocytes in culture efficiently accumulate copper by processes that include both the copper transporter Ctr1 and Ctr1-independent mechanisms. Exposure of astrocytes to copper induces an increase in cellular glutathione (GSH) content as well as synthesis of metallothioneins, suggesting that excess of copper is stored as complex with GSH and in metallothioneins. Furthermore, exposure of astrocytes to copper accelerates the release of GSH and glycolytically generated lactate. Astrocytes are able to export copper and express the Menkes protein ATP7A. This protein undergoes reversible, copper-dependent trafficking between the trans-Golgi network and vesicular structures. The ability of astrocytes to efficiently take up, store and export copper suggests that astrocytes play a key role in the supply of neurons with copper and that astrocytes should be considered as target for therapeutic interventions that aim to correct disturbances in brain copper homeostasis. PMID:23503037

Dringen, Ralf; Scheiber, Ivo F; Mercer, Julian F B

2013-01-01

229

Zeolite crystal growth in space - What has been learned  

NASA Technical Reports Server (NTRS)

Three zeolite crystal growth experiments developed at WPI have been performed in space in last twelve months. One experiment, GAS-1, illustrated that to grow large, crystallographically uniform crystals in space, the precursor solutions should be mixed in microgravity. Another experiment evaluated the optimum mixing protocol for solutions that chemically interact ('gel') on contact. These results were utilized in setting the protocol for mixing nineteen zeolite solutions that were then processed and yielded zeolites A, X and mordenite. All solutions in which the nucleation event was influenced produced larger, more 'uniform' crystals than did identical solutions processed on earth.

Sacco, A., Jr.; Thompson, R. W.; Dixon, A. G.

1993-01-01

230

Hierarchical zeolites from class F coal fly ash  

NASA Astrophysics Data System (ADS)

Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons up to C9, a performance attesting the hierarchal pore structure. The preliminary techno-economic feasibility assessment demonstrates a net energy saving of 75% and cost saving of 63% compared to the commercial zeolite manufacturing process.

Chitta, Pallavi

231

Ion exchange of ammonium in natural and synthesized zeolites.  

PubMed

In this study, zeolite Na-P and Na-Y was prepared by hydrothermal treatment of the Chinese natural clinoptilolite with NaOH. The ion exchange of NH4+ into the three zeolites in the temperature range of 288-333K was also investigated, and the thermodynamic parameters were calculated. The selectivity sequence for NH4+ entering the sodium form of the three materials was Na-clinoptilolite>Na-Y>Na-P, as indicated by values of DeltaG degrees . The results demonstrated that the Si/Al molar ratio of zeolites determined the selectivity for NH4+. PMID:18417280

Wang, Yifei; Lin, Feng; Pang, Wenqin

2008-12-30

232

Radiation effects on a zeolite ion exchanger and a pollucite  

SciTech Connect

Cation exchange capacity and selective Cs and Sr ion sorption measurements were found to be too insensitive to detect radiation effects on irradiated Ionsiv-IE-95 zeolite. However, leaching the zeolite while under ..gamma..-irradiation caused a modest increase in the desorption of exchangeable ions. Gamma-irradiation and subsequent leaching of a natural pollucite also slightly enhanced the leachability of this material. The increased desorption of ions from the zeolite and the enhanced leachability of the pollucite are apparently caused by a decrease in pH due to the generation of acidic species during irradiation.

Komarneni, S.; Palau, G.L.; Pillay, K.K.S.

1983-01-01

233

Method of preparing sodalite from chloride salt occluded zeolite  

DOEpatents

A method is described for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000 K to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

Lewis, M.A.; Pereira, C.

1997-03-18

234

Zeolite-filled PDMS membranes. 1. Sorption of halogenated hydrocarbons  

SciTech Connect

Aiming at a more thorough understanding of the influence of zeolite fillers in PDMS membranes on the pervaporation of chlorinated hydrocarbons from aqueous solutions, the sorption aspect of this separation process was studied. Firstly, the sorption of water and five different chlorinated hydrocarbons was investigated in the zeolite and the polymer separately. Secondly, the composite system was considered and conclusions were drawn concerning interactions at the zeolite-polymer interphase. Finally, the sorption results obtained on the self-synthesized membranes were compared with measurements on commercially available PDMS membranes (GFT). 23 refs., 11 figs., 3 tabs.

Vankelecom, I.F.J.; Dotermont, C.; Morobe, M.; Uytterhoeven, J.B.; Vandecasteele, C. [Katholieke Universiteit Leuven (Belgium)] [Katholieke Universiteit Leuven (Belgium)

1997-03-20

235

Quantitatively Probing the Al Distribution in Zeolites  

SciTech Connect

The degree of substitution of Si4+ by Al3+ in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al-distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

Vjunov, Aleksei; Fulton, John L.; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K.; Govind, Niranjan; Camaioni, Donald M.; Hu, Jian Z.; Lercher, Johannes A.

2014-06-11

236

Catalytic pyrolysis using UZM-44 aluminosilicate zeolite  

DOEpatents

A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

Nicholas, Christopher P; Boldingh, Edwin P

2013-12-17

237

Catalytic pyrolysis using UZM-44 aluminosilicate zeolite  

DOEpatents

A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

Nicholas, Christopher P; Boldingh, Edwin P

2014-04-29

238

Evaluation of natural zeolite as microorganism support medium in nitrifying batch reactors: influence of zeolite particle size.  

PubMed

An evaluation of natural zeolite as a microorganism carrier in nitrifying reactors operated in batch mode was carried out. Specifically, the influence of zeolite particle sizes of 0.5, 1.0 and 2.0 mm in diameter on microorganism adherence to zeolite, ammonium adsorption capacity and the identification of microbial populations were assessed. The greatest amount of total biomass adhered was observed for a zeolite particle size of 1 mm (0.289 g) which was achieved on the 12th day of operation. The highest ammonium adsorption capacity was observed for a zeolite particle size of 0.5 mm, which was 64% and 31% higher than that observed for particle sizes of 1.0 and 2.0 mm, respectively. The maximum de-sorption values were also found for a zeolite particle size of 0.5 mm, although when equilibrium was reached the ammonium concentrations were similar to those observed for a zeolite particle size of 1.0 mm. It was also found that the experimental data on ammonium adsorption fitted very well to the Freundlich isotherm for the three particle sizes studied. Finally, the nitrifying reactors showed similar microbial populations independently of the particle size used as microorganism carrier. The dominant bacterial community was Gammaproteobacteria making up 80% of the total population found. Betaproteobacteria were also identified and made up 12% approx. of the total population. Ammonium Oxidant Betaproteobacteria and Nitrobacter were also detected. PMID:22320694

Mery, C; Guerrero, L; Alonso-Gutiérrez, J; Figueroa, M; Lema, J M; Montalvo, S; Borja, R

2012-01-01

239

Molecular Chemistry in a Zeolite: Genesis of a Zeolite Y-Supported Ruthenium Complex Catalyst  

SciTech Connect

Dealuminated zeolite Y was used as a crystalline support for a mononuclear ruthenium complex synthesized from cis-Ru(acac){sub 2}(C{sub 2}H{sub 4}){sub 2}. Infrared (IR) and extended X-ray absorption fine structure spectra indicated that the surface species were mononuclear ruthenium complexes, Ru(acac)(C{sub 2}H{sub 4}){sub 2}{sup 2+}, tightly bonded to the surface by two Ru-O bonds at Al{sup 3+} sites of the zeolite. The maximum loading of the anchored ruthenium complexes was one complex per two Al{sup 3+} sites; at higher loadings, some of the cis-Ru(acac){sub 2}(C{sub 2}H{sub 4}){sub 2} was physisorbed. In the presence of ethylene and H{sub 2}, the surface-bound species entered into a catalytic cycle for ethylene dimerization and operated stably. IR data showed that at the start of the catalytic reaction, the acac ligand of the Ru(acac)(C{sub 2}H{sub 4}){sub 2}{sup 2+} species was dissociated and captured by an Al{sup 3+} site. Ethylene dimerization proceeded 600 times faster with a cofeed of ethylene and H{sub 2} than without H{sub 2}. These results provide evidence of the importance of the cooperation of the Al{sup 3+} sites in the zeolite and the H{sub 2} in the feed for the genesis of the catalytically active species. The results presented here demonstrate the usefulness of dealuminated zeolite Y as a nearly uniform support that allows precise synthesis of supported catalysts and detailed elucidation of their structures.

Ogino, I.; Gates, B.C.

2009-05-22

240

High-silica zeolite nucleation from clear solutions  

E-print Network

. This work initially tried to apply the insights developed from the TPAsilicalite- 1 clear solution synthesis by investigating the nanoparticles formation and zeolite growth in several tetraethyl orthosilicate (TEOS)-organocation-water solutions heated at 368...

Cheng, Chil-Hung

2006-04-12

241

Oxidation of bioethanol using zeolite-encapsulated gold nanoparticles.  

PubMed

With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high activity and selectivity for the catalytic gas-phase oxidation of ethanol are demonstrated. The zeolites are modified by a recrystallization process, which creates intraparticle voids and mesopores that facilitate the formation of small and disperse nanoparticles upon simple impregnation. The individual zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3?nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50?% conversion of ethanol with 98?% selectivity toward acetaldehyde at 200?°C, which (under the given reaction conditions) corresponds to 606?mol?acetaldehyde/mol?Au?hour(-1) . PMID:25196739

Mielby, Jerrik; Abildstrøm, Jacob Oskar; Wang, Feng; Kasama, Takeshi; Weidenthaler, Claudia; Kegnaes, Søren

2014-11-10

242

CO2 capture using zeolite 13X prepared from bentonite  

NASA Astrophysics Data System (ADS)

Zeolite 13X was prepared using bentonite as the raw material by alkaline fusion followed by a hydrothermal treatment without adding any extra silica or alumina sources. The prepared zeolite 13X was characterized by X-ray powder diffraction, N2-adsorption-desorption measurements, and scanning electron microscopy. The CO2 capture performance of the prepared zeolite 13X was examined under both static and flow conditions. The prepared zeolite 13X showed a high BET surface area of 688 m2/g with a high micropore volume (0.30 cm3/g), and exhibited high CO2 capture capacity (211 mg/g) and selectivity to N2 (CO2/N2 = 37) at 25 °C and 1 bar. In addition, the material showed fast adsorption kinetics, and stable CO2 adsorption-desorption recycling performance at both 25 and 200 °C.

Chen, Chao; Park, Dong-Wha; Ahn, Wha-Seung

2014-02-01

243

Net charge and polarizability of zeolitic Brønsted acidic sites  

NASA Astrophysics Data System (ADS)

The interacting induced-dipoles polarization model, implemented in our program POLAR, is used for the calculation of the effective polarizability of the zeolitic bridged OH group, which results much higher than that of the free silanol group. A high polarizability is also calculated for the bridged OH group with a Si4+, in the absence of Lewis-acid promotion of silanol by Al3+. The crystal polarizability is estimated from the Clausius-Mossotti relationship. Siliceous zeolites are low-permittivity isolators. The interaction of a weak base with the zeolitic OH can be considered as a local bond. Only when cations are located in the zeolite micropore, next to tetrahedra that contain trivalent cations, are large electrostatic fields generatedE They are short ranged, and the positive cation charges are compensated.0

Torrens, F.; Castellano, G.

244

12. INTERIOR OF BUILDING 2, ORIGINAL ZEOLITE PLANT, AT WEYMOUTH ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. INTERIOR OF BUILDING 2, ORIGINAL ZEOLITE PLANT, AT WEYMOUTH LOOKING WEST TO FOUNTAIN. STAIRWAY RUNS DOWN TO FILTRATION BAYS. - F. E. Weymouth Filtration Plant, 700 North Moreno Avenue, La Verne, Los Angeles County, CA

245

Zeolite an efficient catalyst for the Biginelli condensation reaction  

Microsoft Academic Search

A zeolite catalyzed, single step and environmentally friendly process for synthesis of classical Biginelli reaction was investigated.\\u000a For this reaction Transition metal\\/Y zeolites were prepared by microwave solid-state and aqueous solution ion-exchange methods.\\u000a The yield of reactions was increased in order of CuY > CoY > NiY > MnY ? FeY > VY > CrY > ZnY for the solid-state zeolite\\u000a ion-exchange and CuY > CoY > NiY > MnY > CrY > VY > ZnY > FeY for the aqueous solution ion-exchange. The solid-state ion-exchange\\u000a zeolite by

Mojgan Zendehdel; A. Mobinikhaledi; A. Asgari

2008-01-01

246

COPPER DEFICIENCY PROPHYLAXIS IN GRAZING SHEEP BY COPPER OXIDE INJECTION  

E-print Network

COPPER DEFICIENCY PROPHYLAXIS IN GRAZING SHEEP BY COPPER OXIDE INJECTION M. LAMAND Claudine LAB R of insoluble and non ionized form of injected copper has been shown in a previous paper (Lamand, 1978 it appeared that copper oxide was preferable to metallic copper, being slightly less caustic. Inflammation

Boyer, Edmond

247

Cadmium adsorption on vermiculite, zeolite and pumice: Batch experimental studies  

Microsoft Academic Search

Batch experiments were performed to evaluate the combined effects of ionic activity, pH, and contact time on the cadmium sorption in three different minerals, vermiculite, zeolite, and pumice, commonly employed as substrata in nurseries and recently considered for their potential use in remediation methods. The extent of cadmium sorption was vermiculite>zeolite>pumice, as shown by the Langmuir and Freundlich parameters, and

Maria Rosaria Panuccio; Agostino Sorgonà; Marcella Rizzo; Giovanni Cacco

2009-01-01

248

Radiation effects on a zeolite ion exchanger and a pollucite  

Microsoft Academic Search

Cation exchange capacity and selective Cs and Sr ion sorption measurements were found to be too insensitive to detect radiation effects on irradiated Ionsiv-IE-95 zeolite. However, leaching the zeolite while under ..gamma..-irradiation caused a modest increase in the desorption of exchangeable ions. Gamma-irradiation and subsequent leaching of a natural pollucite also slightly enhanced the leachability of this material. The increased

S. Komarneni; G. L. Palau; K. K. S. Pillay

1983-01-01

249

Zeolites and mesoporous materials as advanced functional material  

Microsoft Academic Search

With their unique regular channel system, porous materials offer a wide range of applications as host-guest system ranging from membranes with a molecular sieve function to devices with laser or sensor function. The state of the art of the development of zeolites and zeolite-like materials as advanced materials with (i) separation, (ii) electric\\/electronic, and (iii) optical functions is evaluated.

2004-01-01

250

Removal of Metal Cations from Water Using Zeolites  

Microsoft Academic Search

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-four zeolite samples were analyzed by x-ray diffraction and inductively coupled plasma. These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. Bulk densities of a sized fraction (-40, +65 mesh) varied from 0.48 to 0.93 g\\/mL. Attrition losses ranged from 1 to

M. J. Zamzow; J. E. Murphy

1992-01-01

251

Metal ion exchange by natural and modified zeolites  

Microsoft Academic Search

The lead and cadmium removal from wastewaters by natural and pretreatment zeolites was examined by using a batch-type method. The results demonstrated that the natural zeolites contained a complement of exchangeable Na, K and Ca ions but exposing them to 2 M NaCl solution at 22 and 70°C, respectively, converted them to a near homoionic state in Na-form. Lead and

L. ?urkovi?; Š. Cerjan-Stefanovi?; T. Filipan

1997-01-01

252

Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation  

Microsoft Academic Search

A seeded growth method for the fabrication of high-permeance, high-separation-factor zeolite (siliceous ZSM-5, [Si96O192]-MFI) membranes is reported. The method consists of growing the crystals of an oriented seed layer to a well-intergrown film by avoiding events that lead to a loss of preferred orientation, such as twin overgrowths and random nucleation. Organic polycations are used as zeolite crystal shape modifiers

Zhiping Lai; Griselda Bonilla; Isabel Diaz; Jose Geraldo Nery; Khristina Sujaoti; Miguel A. Amat; Efrosini Kokkoli; Osamu Terasaki; Robert W. Thompson; Michael Tsapatsis; Dionisios G. Vlachos

2003-01-01

253

Electrochemical regeneration of zeolites and the removal of ammonia  

Microsoft Academic Search

The electrochemical regeneration of zeolites was investigated with the objective of removing ammonia from water harmlessly and reusing the regeneration solution in an undivided electrochemical cell assembled with a Ti\\/IrO2–Pt anode and a Cu\\/Zn cathode. Zeolites could be completely regenerated through the electrochemical method in this study. With NaCl as a supporting electrolyte, the conversion rate of ammonia adsorbed by

Xiaohui Lei; Miao Li; Zhenya Zhang; Chuanping Feng; Wei Bai; Norio Sugiura

2009-01-01

254

A theoretical explanation of solvent effects in zeolite catalysis  

Microsoft Academic Search

In a previous study of solid acid catalysis (Nature (1998) 389, 832) we showed that the catalytic activity of zeolites could\\u000a be increased by the coadsorption of “solvent” molecules, such as nitromethane. These coadsorbates do not participate directly\\u000a in the reaction, but alter the environment within the zeolite such that reactivity is increased. In this work we provide further\\u000a theoretical

John B. Nicholas

1999-01-01

255

Zeolite synthesis from fly ash and cement kiln dust  

SciTech Connect

Zeolites added to portland cement paste normally undergo a pozzolanic reaction. However, if the composition of the cement is modified by blending it with fly ash, the calcium silicate hydrate (C-S-H) that forms has a low CaO/SiO{sub 2} ratio which allows it to coexist with a zeolite. In fact, if one adds alkali to the system, it then becomes possible to nucleate and grow a zeolitic phase with C-S-H. Normally zeolites that form from fly ash and NaOH include NaP-1 and analcime. But when the fly ash and NaOH are mixed with cement kiln dust, cancrinite-like phases and tobermorite form instead. This implies that a zeolite-containing monolith could be produced that would exhibit both the cation-exchange and adsorptive properties of zeolites while retaining the characteristic strength and ease of use attributable to cement based materials. These composites show promise as a new class of inexpensive cation exchange and/or chemical adsorbents that can be used for large scale applications.

Grutzeck, M.W. [Pennsylvania State Univ., University Park, PA (United States)

1996-12-31

256

Synthesis and characterization of nanocrystalline and mesoporous zeolites  

NASA Astrophysics Data System (ADS)

Mesoporous aggregates of nanocrystalline zeolites with MFI and BEA frameworks have been synthesized using a one-pot and single structure directing agent. The effect of different reaction conditions, such as temperature, time, pH and water content, on the particle size, surface area and mesopore volume has been studied. Nanocrystalline and mesoporous ZSM-5, beta and Y zeolites were modified with different transition metals and the resulting single- and double metal containing catalyst materials were characterized. Nanocrystalline Silicalite-1 zeolite samples with varying particle size were functionalized with different organosilane groups and the cytotoxic activity of the zeolite nanocrystals was studied as a function of particle size, concentration, organic functional group type, as well as the type of cell line. Framework stability of nanocrystalline NaY zeolite was tested under different pH conditions. The synthesized zeolites used in this work were characterized using a variety of physico-chemical methods, including powder X-ray diffraction, Solid State NMR, nitrogen sorption, electron microscopy, Inductively Coupled Plasma -- Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy.

Petushkov, Anton

2011-12-01

257

Zeolitic ammonium ion exchange for portable hemodialysis dialysate regeneration.  

PubMed

Ammonia removal from a recirculating dialysate stream is a major challenge in developing a truly portable, regenerable hemodialysis system. Three zeolites, type F, type W, and clinoptilolite, were found to have good ammonia ion exchange capacity with linear equilibrium ion exchange coefficients of 0.908, 0.488, and 0.075 L/g, respectively. The linear equilibrium ion exchange coefficient relates dialysate ammonia concentration (mumol/L) to the amount of ammonia absorbed by zeolite (mumol/g) at equilibrium. Ammonia uptake by zeolite powders was fast, with equilibrium reached within 15 sec. Zeolite ammonia ion exchange and regeneration through multiple cycles was studied using an ion exchange column containing clinoptilolite pellets. Zeolite ion exchange capability was regenerated by flushing the column with 2 mol/L sodium chloride after an ion exchange run. The column maintained ammonia ion exchange capacity through six ion exchange/regeneration cycles, demonstrating multiple dialysis use possibilities. Atomic absorption spectroscopy of the column effluent showed no detectible (< 1 part per million) Si or Al leached from the zeolite. PMID:7640432

Patzer, J F; Yao, S J; Wolfson, S K

1995-01-01

258

Characterization of Chemical Properties, Unit Cell Parameters and Particle Size Distribution of Three Zeolite Reference Materials: RM 8850 - Zeolite Y, RM 8851 - Zeolite A and RM 8852 - Ammonium ZSM-5 Zeolite  

SciTech Connect

Zeolites have important industrial applications including use as catalysts, molecular sieves and ion exchange materials. In this study, three zeolite materials have been characterized by the National Institute of Standards and Technology (NIST) as reference materials (RMs): zeolite Y (RM 8850), zeolite A (RM 8851) and ZSM-5 zeolite (RM 8852). They have been characterized by a variety of chemical and physical measurement methods: X-ray fluorescence (XRF), gravimetry, instrumental neutron activation analysis (INAA), nuclear magnetic resonance (NMR), calorimetry, synchrotron X-ray diffraction, neutron diffraction, laser light extinction, laser light scattering, electric sensing zone, X-ray sedimentation, scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and optical microscopy. The chemical homogeneity of the materials has been characterized. Reference values are given for the major components (major elements, loss on ignition [LOI] and loss on fusion [LOF]), trace elements and Si/Al and Na/Al ratios. Information values are given for enthalpies of formation, unit cell parameters, particle size distributions, refractive indices and variation of mass with variation in relative humidity (RH). Comparisons are made to literature unit cell parameters. The RMs are expected to provide a basis for intercomparison studies of these zeolite materials.

Turner,S.; Sieber, J.; Vetter, T.; Zeisler, R.; Marlow, A.; Moreno-Ramirez, M.; Davis, M.; Kennedy, G.; Borghard, W.; et al

2008-01-01

259

Following the movement of Cu ions in a SSZ-13 zeolite during dehydration, reduction and adsorption: a combined in situ TP-XRD, XANES/DRIFTS study  

SciTech Connect

Cu-SSZ-13 has been shown to possess high activity and superior N2 formation selectivity in the selective catalytic reduction of NOx under oxygen rich conditions. Here, a combination of synchrotron-based (XRD and XANES) and vibrational (DRIFTS) spectroscopy tools have been used to follow the changes in the location and coordination environment of copper ions in a Cu-SSZ-13 zeolite during calcinations, reduction with CO, and adsorption of CO and H2O. XANES spectra collected during these procedures provides critical information not only on the variation in the oxidation state of the copper species in the zeolite structure, but also on the changes in the coordination environment around these ions as they interact with the framework, and with different adsorbates (H2O and CO). Time-resolved XRD data indicate the movement of copper ions and the consequent variation of the unit cell parameters during dehydration. DRIFT spectra provide information about the adsorbed species present in the zeolite, as well as the oxidation states of and coordination environment around the copper ions. A careful analysis of the asymmetric T-O-T vibrations of the CHA framework perturbed by copper ions in different coordination environments proved to be especially informative. The results of this study will aid the identification of the location, coordination and oxidation states of copper ions obtained during in operando catalytic studies. Financial support was provided by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. Part of this work (sample preparation) was performed in the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). The EMSL is a national scientific user facility supported by the US DOE, Office of Biological and Environmental Research. PNNL is a multi-program national laboratory operated for the US DOE by Battelle. All of the spectroscopy work reported here was carried out at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). NSLS is a national scientific user facility supported by the US DOE.

Kwak, Ja Hun; Varga, Tamas; Peden, Charles HF; Gao, Feng; Hanson, Jonathan C.; Szanyi, Janos

2014-05-05

260

Synthesis of core-shell structured zeolite-A@mesoporous silica composites for butyraldehyde adsorption.  

PubMed

A simple sol-gel process is followed to construct a thin layer of mesoporous silica shell core-shell structure on micrometer sized and nanometer sized zeolite A (micro-zeolite A@SiO2 and nano-zeolite A@SiO2 respectively). Further thickness of the silica shells has been tuned from 20 to 50 nm while the zeolite A particle size changes from nanometer to micrometer. Pores of the silica shells arranged orderly on the crystal-faces of zeolite-A cores. Typically, adsorption amount of the butyraldehyde towards these core-shell composite materials is investigated well and is verified to be almost double than that of the pristine zeolite A. Interestingly the nano-zeolite A core containing core-shell composite absorbs maximum butyraldehyde (314 mg/g) compared to the micro-zeolite A (266 mg/g), even if the mesoporous shell thickness of the nano-zeolite A@SiO2 composites is less (20 nm) than that of micro-zeolite A@SiO2 (50 nm). Both of these values are significantly larger than the pristine zeolite A (nano-zeolite A; 151 mg/g and micro-zeolite A; 146 mg/g). PMID:24910060

Yu, Haijun; Lv, Yingying; Ma, Kuoyan; Wang, Changguo; Xue, Zhaoteng; Zhao, Yujuan; Deng, Yonghui; Dai, Ya; Zhao, Dongyuan

2014-08-15

261

HEALTH MATTERS Copper T IUD  

E-print Network

HEALTH MATTERS Copper T IUD What is the Copper T IUD? The Copper T IUD is one of two types of intrauterine devices available in the United States. The Copper T IUD is a small, flexible device made of soft plastic and copper. It is easily and quickly inserted into the uterus by a health care provider to prevent

Yener, Aylin

262

Readers of histone modifications  

Microsoft Academic Search

Histone modifications not only play important roles in regulating chromatin structure and nuclear processes but also can be passed to daughter cells as epigenetic marks. Accumulating evidence suggests that the key function of histone modifications is to signal for recruitment or activity of downstream effectors. Here, we discuss the latest discovery of histone-modification readers and how the modification language is

Miyong Yun; Jun Wu; Jerry L Workman; Bing Li

2011-01-01

263

Preparation of zeolite NaA for CO2 capture from nickel laterite residue  

NASA Astrophysics Data System (ADS)

Zeolite NaA was successfully prepared from nickel laterite residue for the first time via a fusion-hydrothermal procedure. The structure and morphology of the as-synthesized zeolite NaA were characterized with a range of experimental techniques, such as X-ray diffraction, scanning electronic microscopy, and infrared spectroscopy. It was revealed that the structures of the produced zeolites were dependent on the molar ratios of the reactants and hydrothermal reaction conditions, so the synthesis conditions were optimized to obtain pure zeolite NaA. Adsorption of nitrogen and carbon dioxide on the prepared zeolite NaA was also measured and analyzed. The results showed that zeolite NaA could be prepared with reasonable purity, it had physicochemical properties comparable with zeolite NaA made from other methods, and it had excellent gas adsorption properties, thus demonstrating that zeolite NaA could be prepared from nickel laterite residue.

Du, Tao; Liu, Li-ying; Xiao, Penny; Che, Shuai; Wang, He-ming

2014-08-01

264

First zeolite carbon replica with a well resolved X-ray diffraction pattern.  

PubMed

The present study demonstrates that for the nanocasting process with zeolites, a careful choice of the zeolite structure type (EMT) allows the formation of faithful carbon replica exhibiting up to three well resolved XRD peaks. PMID:16491186

Gaslain, Fabrice O M; Parmentier, Julien; Valtchev, Valentin P; Patarin, Joël

2006-03-01

265

Adsorption and isothermal models of atrazine by zeolite prepared from Egyptian kaolin  

NASA Astrophysics Data System (ADS)

The adsorption behavior of Atrazine on zeolites, prepared from Egyptian kaolin, has been studied in order to consider the application of these types of zeolites in water purification. The batch mode has been employed, using atrazine solution of concentration ranging from 2 to 10 mg /l. The adsorption capacity and distribution coefficients ( Kd) were determined for the adsorption system as a function of sorbate concentration. It was found that, under the studies concentrations, the percent of adsorbed atrazine on both zeolites match to Langmuir and Freundlich adsorption models. The constants of each model were calculated to assess the adsorption behavior of atrazine on each type of zeolite. According to the equilibrium studies, adsorption of atrazine on zeolite X at lower concentrations is much better than that on zeolite A. The application of Dublin-Kaganer-Radushkevich model revealed physisorption endothermic adsorption process for both zeolites. These results show that natural zeolites hold great potential to remove hazardous materials such as atrazine from water.

Jamil, Tarek S.; Gad-Allah, Tarek A.; Ibrahim, Hanan S.; Saleh, Tamer S.

2011-01-01

266

Diffusion of an alkane molecule in siliceous zeolite beta Matthew Aronson  

E-print Network

1 Diffusion of an alkane molecule in siliceous zeolite beta Matthew was performed to study the diffusion of an alkane molecule in siliceous zeolite beta, as a function of chain length and temperature. The alkane was modeled

Shell, M. Scott

267

Hot isostatic pressing of copper canisters for nuclear waste disposal  

Microsoft Academic Search

This paper describes the copper canisters designed by the Swedes for nuclear waste disposal. The canister is a large, plain, cylindrical can into which the spent nuclear fuel elements can be packed and sealed for final disposal. Two canister modifications are shown which have been developed, differing only in the method of packing the fuel elements into the canister. Both

Lyman

1984-01-01

268

The use Na, Li, K cations for modification of ZSM-5 zewolite to control hydrocarbon cold-start emission  

SciTech Connect

This paper addresses the problem of controlling hydrocarbon emissions from cold-start of engines by investigating the adsorbents which could adsorb the hydrocarbons at cold temperatures and hold them to 250-300 ?. The materials, that has been studied, are based on the modification of ZSM-5 (SiO{sub 2}/Al{sub 2}O{sub 3} = 35) zeolite with Li, K, Na cations. It has been shown that the introduction of Li, Na and K in an amount that is equivalent to the content of Al in zeolite results in occurrence of toluene temperature desorption peaks at high-temperatures. The toluene temperature desorption curves for 5%Li-ZSM-5 and 2.3%Na-ZSM-5 zeolites are identical and have peak toluene desorption rate between 200 to 400 ?. Upon analysis of toluene adsorption isotherms for 2.3%Na-ZSM-5 and 5%Li-ZSM-5, it was concluded that the toluene diffusion inside of the modified zeolites channels is extremely slow and the sorption capacity of 2.3%Na-ZSM-5 is higher than with 5%Li-ZSM-5. The 2.3%Na-ZSM-5 didn't change toluene temperature programmed desorption (TPD) rate of curve after the treatment in environment with 10% ?{sub 2}? at 750-800 ? for about 28 h. The 2.3%Na-ZSM-5 zeolite is very promising as adsorbent to control the cold-start hydrocarbon emissions.

Golubeva V.; Rohatgi U.; Korableva, A.; Anischenko, O.; Kustov, L.; Nissenbaum, V; Viola, M.B.

2012-08-29

269

Microwave-assisted hydrothermal synthesis of zeolite films on ceramic supports  

Microsoft Academic Search

Zeolite films were formed on ceramic supports by a novel microwave-assisted hydrothermal method and were characterized by\\u000a XRD, SEM, FTIR and BET surface area. The two-stage synthesis technique consists of microwave heating of supports saturated\\u000a with precursor solution to form a thin layer of zeolite nano-seeds, followed by hydrothermal treatment to crystallize MFI\\u000a zeolite. The resulting zeolite formation time was

C. D. Madhusoodana; R. N. Das; Y. Kameshima; K. Okada

2006-01-01

270

Gas detection with SnO 2 sensors modified by zeolite films  

Microsoft Academic Search

Zeolite films have been grown on top of SnO2 sensors to modify their response to gas phase molecules with the aim of improving their selectivity. To this end SnO2 sensors were first prepared using conventional procedures, and then zeolite layers (silicalite and zeolite A) were grown on the outer SnO2 surface, using different synthesis procedures. The zeolite-modified sensors were tested

Montserrat Vilaseca; Joaquin Coronas; Albert Cirera; Albert Cornet; Joan Ramon Morante; Jesus Santamaria

2007-01-01

271

Influence of zeolites on the sintering and technological properties of porcelain stoneware tiles  

Microsoft Academic Search

Low-cost zeolitic rocks are promising substitutes for feldspathic fluxes in ceramic bodies, since their fusibility, modest hardness and high cation exchange capacity (CEC) should improve grinding and sintering. Five large-scale Italian deposits of natural zeolites with different mineralogy were characterised and tested in porcelain stoneware bodies. Their behaviour during processing was appraised and compared with that of zeolite-free bodies. Zeolites

Roberto de’ Gennaro; Piergiulio Cappelletti; Guido Cerri; Maurizio de’ Gennaro; Michele Dondi; Guia Guarini; Alessio Langella; Debora Naimo

2003-01-01

272

Tubular-type pervaporation module with zeolite NaA membrane  

Microsoft Academic Search

Zeolite NaA membranes were prepared on the surfaces of porous tubular supports composed of mullite, ?-alumina and\\/or cristobalite using the hydrothermal synthesis. The zeolite NaA crystals and the surface morphologies of the membranes were characterized by X-ray diffraction and SEM. EPMA analysis revealed that the zeolite composite membranes consisted of three layers — the zeolite layer, the intermediate layer and

Masakazu Kondo; Mitsuru Komori; Hidetoshi Kita; Ken-ichi Okamoto

1997-01-01

273

The role of zeolite beta nanoparticles solutions in the synthesis of zeolite-functionalised materials with bimodal porosity  

NASA Astrophysics Data System (ADS)

The last decade, much attention has been devoted to the development of bimodal materials with zeolitic properties, with the intention to combine the beneficial properties of zeolites with these of mesoporous structures. Various synthesis methods have been developed, of which several are using zeolite nanoparticles solutions as silica-alumina source to form the mesoporous material. Extensive research has been conducted to the properties and the formation mechanism of both the nanoparticles solution and the final bimodal materials. However, still little is known about the correlation between the characteristics of the initial nanoparticles solution and the structural, chemical and physico-chemical properties of the final materials. The focus of this research is to acquire this lacking knowledge, which would allow tailoring of the final material characteristics, depending on the application requirements. In this PhD work, two types of bimodal materials with zeolitic features are investigated, i.e. a mesotemplate-free method and an impregnation on a mesoporous substrate, both using a zeolite beta nanoparticles solution as precursor. The main focus is put on how the synthesis conditions of the zeolite beta nanoparticles solution influence the final material properties. It is shown that the hydrothermal synthesis temperature (373K--393K--413K--423K/24h) of the zeolite beta nanoparticles solution has a direct impact on the porosity and zeolitic features of the final materials. Moreover, a clear threshold is observed: Synthesis temperatures below or equal to 413K result in bimodal materials without clear zeolitic properties, while a higher temperature of 423K gives materials with clear zeolitic features. Furthermore, this difference in material properties gives better results for the materials above the threshold regarding the acidity, stability and catalytic activity. A transmission electron microscopy and advanced electron tomography study showed that the mesotemplate-free structures are possessing a wormhole-like mesoporous structure, formed by the condensation of nanoparticles via neck formation. Furthermore, the study revealed a 2D growth of the nanoparticles under the threshold and a change towards 3D growth at the threshold temperature of 413K. This suggests a standard sol-mechanism below and at the threshold, and indicates an interruption of this mechanism by the start of the crystallisation process above 413K.

Van Oers, Cynthia J.

274

Toward a Database of Hypothetical Zeolite Structures David J. Earl, and Michael W. Deem*,  

E-print Network

Toward a Database of Hypothetical Zeolite Structures David J. Earl, and Michael W. Deem the sampling. We discuss construction of a database of hypothetical zeolite frameworks with this approach and discuss how the database may be used to search for new zeolite structures with specific material

Earl, David J.

275

Ion exchange of zeolite membranes by a vacuum `flow-through' Seok-Jhin Kim a  

E-print Network

Ion exchange of zeolite membranes by a vacuum `flow-through' technique Seok-Jhin Kim October 2014 Keywords: Ion exchange Zeolite membrane Flow-through technique Separation Catalysis a b s t r a c t Ion exchange of nanoporous (e.g., zeolite) membranes is of increasing importance

Nair, Sankar

276

Catalytic Transformation of C7-C9 Methyl Benzenes over USY-based FCC Zeolite Catalyst  

E-print Network

Catalytic Transformation of C7-C9 Methyl Benzenes over USY-based FCC Zeolite Catalyst S. Al (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over USY based FCC zeolite catalyst for the m-xylene. December 2005 Keywords: FCC zeolite catalyst; USY; Toluene; m-Xylene; Disproportionation

Al-Khattaf, Sulaiman

277

Zeolite-Mediated Photochemical Charge Separation Using a Surface-Entrapped Ruthenium-Polypyridyl Complex  

E-print Network

Zeolite-Mediated Photochemical Charge Separation Using a Surface-Entrapped Ruthenium)ethenyl]benzene (L), a polypyridyl complex of ruthenium(II) was tethered on the surface of zeolite Y. Electrochemical photolysis of the ruthenium-zeolite solid ion-exchanged with diquat and suspended in a propyl viologen

Dutta, Prabir K.

278

Dealumination–aging pattern of REUSY zeolites contained in fluid cracking catalysts  

Microsoft Academic Search

The evolution of the properties of a REUSY zeolite contained in a fluid cracking catalyst was investigated under laboratory steam deactivation procedures and in age fractions of the corresponding equilibrium catalyst (Ecat). The aging pattern, defined by the evolution of the zeolite surface area (ZSA) related to the decrease of the unit cell size (UCS), was similar between lab-steamed zeolites

Francisco Hernández-Beltrán; Juan Carlos Moreno-Mayorga; Mar??a de Lourdes Guzmán-Castillo; Juan Navarrete-Bolaños; Montserrat González-González; Brent E. Handy

2003-01-01

279

Properties of Zeolite A Obtained from Powdered Laundry Detergent: An Undergraduate Experiment.  

ERIC Educational Resources Information Center

Presents experiments that introduce students to the myriad properties of zeolites using the sodium form of zeolite A (Na-A) from laundry detergent. Experiments include extracting Na-A from detergent, water softening properties, desiccant properties, ion-exchange properties, and Zeolite HA as a dehydration catalyst. (JRH)

Smoot, Alison L.; Lindquist, David A.

1997-01-01

280

Framework-Type Determination for Zeolite Structures in the Inorganic Crystal Structure Database  

NASA Astrophysics Data System (ADS)

In this work a structural characterization of zeolite crystals is performed by identifying the framework type to which each zeolite belongs. The framework type is assigned for 1433 zeolite database entries in the FIZ/NIST Inorganic Crystal Structure Database (ICSD) populating 95 framework types. These entries correspond to both natural and synthetic zeolites. Each ICSD entry is based on published work containing crystallographic information of the zeolite crystalline structure and some physical and chemical data. Today, the Structure Commission of the International Zeolite Association recognizes crystalline materials as belonging to the "zeolite" family only if they possess one of the approved framework types by the organization. Such information is of fundamental importance for identifying zeolites, for reference, for zeolite standards, for supporting the discovery of new zeolites, and for crystalline substance selection based on application. Unfortunately, framework-type information is not contained in the ICSD records. The long term goal of this work is filling such gap. Although the ICSD contains an extensive collection of zeolites, inclusion of zeolites belonging to the 191 accepted framework types could substantially expand such collection. The structural determination was achieved via several structural analysis methods based on numerical-computer implementations.

Yang, Shujiang; Lach-hab, Mohammed; Vaisman, Iosif I.; Blaisten-Barojas, Estela; Li, Xiang; Karen, Vicky L.

2010-09-01

281

UTILITY OF SYNTHETIC ZEOLITES IN REMOVAL OF INORGANIC AND ORGANIC WATER POLLUTANTS  

EPA Science Inventory

Zeolites are well known for their ion exchange and adsorption properties. Different inorganic and organic pollutants have been removed from water at room temperature using various zeolites. Synthetic zeolites like ZSM-5, Ferrierite, Beta and Faujasite Y have been used to remove i...

282

Effect of Micropore Topology on the Structure and Properties of Zeolite Polymer Replicas  

E-print Network

Effect of Micropore Topology on the Structure and Properties of Zeolite Polymer Replicas Stacy A Received September 10, 1997X Zeolites were used as templates to prepare microporous polymer replicas. Phenol- formaldehyde polymers were synthesized and cured within the channel networks of zeolites Y

283

Effects of composition and phonon scattering mechanisms on thermal transport in MFI zeolite films  

E-print Network

Effects of composition and phonon scattering mechanisms on thermal transport in MFI zeolite films of different phonon scattering processes on thermal transport in the nanoporous zeolite MFI of Physics. DOI: 10.1063/1.2776006 I. INTRODUCTION Zeolites are nanoporous mixed-oxide crystals with com

Nair, Sankar

284

MFI lamellae are unique among the availa-ble aluminosilicate zeolite lamellae because they  

E-print Network

MFI lamellae are unique among the availa- ble aluminosilicate zeolite lamellae because they have the potential of single­unit cell layers in applications beyond petrochemical processing. Branching of zeolite- plicable to all zeolite structures that can (i) be grown anisotropically as thin layers and (ii) can

Zare, Richard N.

285

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite minerals  

E-print Network

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite, and chlorite) and two natural zeolites are reported here. Pressed powders of sizeseparated phyllosilicate and natural zeolite samples were heated incrementally from 100°C to 900°C, cooled to room temperature

Glotch, Timothy D.

286

The comparative ion exchange capacities of natural sedimentary and synthetic zeolites  

Microsoft Academic Search

A large tonnage of natural, sedimentary zeolites is found in the Western United States and world-wide. They offer a substantial potential for a variety of industrial uses including the removal of cations from acid mine drainage and industrial waste waters. There is a wide variation in the cation exchange capacity of zeolites because of the differing nature of various zeolite

K. D. Mondale; R. M. Carland; F. F. Aplan

1995-01-01

287

Materials Chemistry and Physics 83 (2004) 8995 Microwave preparation of Li-zeolite directly from  

E-print Network

Materials Chemistry and Physics 83 (2004) 89­95 Microwave preparation of Li-zeolite directly from in revised form 3 September 2003; accepted 12 September 2003 Abstract Li-zeolites were successfully and lithium hydroxide as the hydrolytic agent. Many types of Li-zeolites were obtained by controlling

Gulari, Erdogan

288

Sorption of arsenic by surfactant-modified zeolite and kaolinite Zhaohui Li a,*, Ryan Beachner a  

E-print Network

Sorption of arsenic by surfactant-modified zeolite and kaolinite Zhaohui Li a,*, Ryan Beachner Available online 2 April 2007 Abstract In this study, the feasibility of using surfactant-modified zeolite- adecyltrimethylammonium, a cationic surfactant, on zeolite and kaolinite surfaces exceeded monolayer coverage

Li, Zhaohui

289

Identification of iron cyclam complexes encapsulated inside zeolite Y Xile Hu, Karsten Meyer *  

E-print Network

Identification of iron cyclam complexes encapsulated inside zeolite Y Xile Hu, Karsten Meyer complexes formed inside the supercages of zeolite-Y. Especially interesting is the identification Fe(V) nitrido species. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Zeolite; Cage

Meyer, Karsten

290

Density Functional Theory Investigations of the Direct Oxidation of Methane on an Fe-Exchanged Zeolite  

E-print Network

-Exchanged Zeolite WanZhen Liang,,,§ Alexis T. Bell,*, Martin Head-Gordon, and Arup K. Chakraborty, Department-exchange site in the zeolite] is lower in energy by 7.7 kcal/mol, assuming a spin multiplicity M ) 6-exchanged ZSM-5 zeolite pretreated at an elevated temperature with N2O and then exposed to methane at room

Bell, Alexis T.

291

Methyl rotational tunneling dynamics of p-xylene confined in a crystalline zeolite host  

E-print Network

Methyl rotational tunneling dynamics of p-xylene confined in a crystalline zeolite host Sankar-xylene confined in nanoporous zeolite crystals has been measured by inelastic neutron scattering INS and proton to the methyl-zeolite interactions. The INS tunneling spectra from the crystals space group P212121 with four

Nair, Sankar

292

Modeling Spontaneous Formation of Precursor Nanoparticles in Clear-Solution Zeolite Synthesis  

E-print Network

Modeling Spontaneous Formation of Precursor Nanoparticles in Clear-Solution Zeolite Synthesis M zeolite. Silica condensation/hydrolysis is modeled by a nearest-neighbor attraction, while growth by Ostwald ripening. We suggest that this mechanism may play a role in the growth of zeolite

Auerbach, Scott M.

293

Locating stationary points of sorbate-zeolite potential energy surfaces using interval analysis  

E-print Network

Locating stationary points of sorbate-zeolite potential energy surfaces using interval analysis in a zeolite can be studied using transition-state theory. In this application, and other applications points, transition states, zeolites, diffusion, interval-Newton method Author to whom all correspondence

Stadtherr, Mark A.

294

UV-Raman spectroscopy on nanotubes@zeolite Wavelength dependence Ab initio calculations  

E-print Network

UV-Raman spectroscopy on nanotubes@zeolite June, 2005 Wavelength dependence Ab initio calculations involving the peak at 650 cm-1. Nanotubes grown inside the channels of zeolite crystals are constrained in the zeolite. · Further peaks cannot be explained by only 4 °A-diameter nanotubes. · Calculations

Nabben, Reinhard

295

Spectroscopic Studies of Colloidal Solutions of Nanocrystalline Ru(bpy)3 2+-Zeolite Y  

E-print Network

Spectroscopic Studies of Colloidal Solutions of Nanocrystalline Ru(bpy)3 2+-Zeolite Y Norma B of Ru(bpy)3 2+-zeolite Y has made it possible to use conventional optical transmission spectroscopic methods to examine the entrapped Ru(bpy)3 2+ species within the zeolite. To prepare the suspensions

Dutta, Prabir K.

296

Removal of Heavy Metals and Other Cations from Wastewater Using Zeolites  

Microsoft Academic Search

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-two zeolites were analyzed by X-ray diffraction and inductively coupled plasma analysis (ICP). These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. The zeolites were primarily in the sodium or calcium form, but potassium and magnesium counter ions were also present. Bulk

M. J. Zamzow; B. R. Eichbaum; K. R. Sandgren; D. E. Shanks

1990-01-01

297

Framework stabilization of Si-rich LTA zeolite prepared in organic-free media.  

PubMed

Zeolite HOU-2 (LTA type) is prepared with the highest silica content (Si/Al = 2.1) reported for Na-LTA zeolites without the use of an organic structure-directing agent. The rational design of Si-rich zeolites has the potential to improve their thermal stability for applications in catalysis, gas storage, and selective separations. PMID:25347029

Conato, Marlon T; Oleksiak, Matthew D; Peter McGrail, B; Motkuri, Radha K; Rimer, Jeffrey D

2015-01-01

298

Microwave-assisted preparation of zeolite KH from alumatrane and Mathavee Sathupunya a  

E-print Network

Microwave-assisted preparation of zeolite K­H from alumatrane and silatrane Mathavee Sathupunya-loaded zeolite was synthesized for the first time, via sol­gel processing and microwave heating techniques on x-ray diffraction analysis, the synthesized product is a K­H zeolite of hitherto unknown structure

Gulari, Erdogan

299

Temperature dependent thermal conductivity of pure silica MEL and MFI zeolite thin films  

E-print Network

Temperature dependent thermal conductivity of pure silica MEL and MFI zeolite thin films Jin Fang,1 dependent cross-plane thermal conductivity of pure silica zeolite (PSZ) MFI and MEL thin films measured of MFI zeolite was predicted and discussed using the Callaway model based on the Debye approximation. VC

Pilon, Laurent

300

Helicity Selective Separation of Zeolite-supported Single-walled Carbon Nanotubes Synthesized from  

E-print Network

1 Helicity Selective Separation of Zeolite-supported Single-walled Carbon Nanotubes Synthesized on metal supported Zeolite.10,11 Purification and helicity selective separation of SWNTs is still an important challenge. Two methods for purification, removal of metal catalysts and Zeolite, of SWNTs produced

Maruyama, Shigeo

301

Surface Structure of Zeolite (MFI) Crystals Isabel Diaz,, Efrosini Kokkoli, Osamu Terasaki, and Michael Tsapatsis*,  

E-print Network

Articles Surface Structure of Zeolite (MFI) Crystals Isabel Di´az,,§ Efrosini Kokkoli, Osamu type MFI) is an important zeolite that, in addition to conventional applications such as adsorption in studies of zeolite crystal growth. The surface structure of silicalite-1 crystals with two different

Kokkoli, Efie

302

Zeolite Surface as a Catalyst Support Material for Synthesis of Single-Walled Carbon Nanotubes  

E-print Network

1 Zeolite Surface as a Catalyst Support Material for Synthesis of Single-Walled Carbon Nanotubes support material. Although zeolite has been frequently used as a catalyst support material for the synthesis of SWNTs, detailed surface properties of previously employed zeolites, and thus their role

Maruyama, Shigeo

303

Neutron and infrared study of the dynamical behaviour of methane in NaA zeolite *  

E-print Network

1029 Neutron and infrared study of the dynamical behaviour of methane in NaA zeolite * E. Cohen de methane molecule adsorbed in the synthetic zeolite NaA shows several interesting features : i-1038 JUILLET 1981, Classification Physics Abstracts 68.45 1. Introduction. - Zeolites are porous alumino

Paris-Sud XI, Université de

304

Zeolite Growth by Addition of Subcolloidal Particles: Modeling and Experimental Validation  

E-print Network

Zeolite Growth by Addition of Subcolloidal Particles: Modeling and Experimental Validation on nucleation and growth of zeolites, their growth mechanism remains elusive. Elucidating the primary growth units partici- pating in and the colloidal interactions that may affect growth of zeolite particles

Kokkoli, Efie

305

Influence of Zeolite Catalyst Supports on the Synthesis of Single-Walled Carbon Nanotubes  

E-print Network

1 Influence of Zeolite Catalyst Supports on the Synthesis of Single-Walled Carbon Nanotubes; catalytic CVD; metal catalyst; Zeolite ABSTRACT: Choice of the catalyst support is an important factor) method. Zeolites, which are a class of microporous crystalline material, have also been known

Maruyama, Shigeo

306

Investigation into the shape selectivity of zeolite catalysts for biomass conversion Jungho Jae a  

E-print Network

Investigation into the shape selectivity of zeolite catalysts for biomass conversion Jungho Jae January 2011 Available online 4 March 2011 Keywords: Zeolite Pyrolysis Glucose Kinetic diameter Pore size Shape selectivity a b s t r a c t We investigate the influence of zeolite pore size and shape

Auerbach, Scott M.

307

Theoretical Study of Zeolite-Catalyzed Dimethoxymethane Carbonylation to Methyl Methoxyacetate  

E-print Network

Theoretical Study of Zeolite-Catalyzed Dimethoxymethane Carbonylation to Methyl Methoxyacetate be catalyzed by acid zeolites. This reaction is a critical step in the synthesis of monoethylene glycol (MEG-FAU zeolites has been investigated using density functional theory. We find that the reaction involves three

Bell, Alexis

308

ZEOLITE PERFORMANCE AS AN ANION EXCHANGER FOR ARSENIC SEQUESTRATION IN WATER  

EPA Science Inventory

Zeolites are well known for their use in ion exchange and acid catalysis reactions. The use of zeolites in anion or ligand exchange reactions is less studied. The NH4+ form of zeolite Y (NY6, Faujasite) has been tested in this work to evaluate its performance for arsenic removal...

309

Purification and characterization of zeolite-supported single-walled carbon nanotubes catalytically synthesized from  

E-print Network

Purification and characterization of zeolite-supported single-walled carbon nanotubes catalytically complete removal of zeolite particles and Fe/Co catalysts from raw single-walled carbon nanotubes (SWNTs-scale production of quasi-aligned multi-walled carbon nanotube bundles on zeolite by CCVD, in which acetylene

Maruyama, Shigeo

310

Molecular simulations of hydrogen and methane permeation through pore mouth modified zeolite Sang Eun Jeea  

E-print Network

Molecular simulations of hydrogen and methane permeation through pore mouth modified zeolite from gas mixtures in order to use hydrogen in energy-related applications. Zeolite membranes are robust zeolite membranes whose pore mouths have been chemically modified. An important challenge for materials

McGaughey, Alan

311

Chromate transport through columns packed with surfactant-modified zeolite/zero valent iron pellets  

E-print Network

Chromate transport through columns packed with surfactant-modified zeolite/zero valent iron pellets Chromate transport through columns packed with zeolite/zero valent iron (Z/ZVI) pellets, either untreated of immobile water was responsible for the earlier breakthrough of chromate in columns packed with zeolite

Li, Zhaohui

312

Micro/Macroporous System: MFI-Type Zeolite Crystals with Embedded Macropores.  

PubMed

Zeolite crystals with an embedded and interconnected macropore system are prepared by using mesoporous silica particles as a silica source and as a sacrificial macroporogen. These novel hierarchical zeolite crystals are expected to reduce diffusion limitations in all zeolite-catalyzed reactions, especially in the transformation of larger molecules like in the catalytic cracking of polymers and the conversion of biomass. PMID:25535114

Machoke, Albert G; Beltrán, Ana M; Inayat, Alexandra; Winter, Benjamin; Weissenberger, Tobias; Kruse, Nadine; Güttel, Robert; Spiecker, Erdmann; Schwieger, Wilhelm

2015-02-01

313

Anchoring of alkylphosphonic derivatives molecules on copper oxide surfaces  

NASA Astrophysics Data System (ADS)

In this study, a new approach of copper surface modification, taking advantage of the oxide layer naturally present, is proposed using phosphonic acids derivatives. Phosphonic acids are a class of molecules particularly known for their spontaneous self-assembly on oxidized substrates. On this basis, copper substrates chemically oxidized using H 2O 2 (5%) were successfully modified with n-dodecylphosphonic acid and 1-pyrrolyl-10-decanephosphonic acids. The oxidation state of copper substrate, just after chemical oxidation, was probed by XPS and PM-IRRAS. Surface characterization was completed by contact angle and AFM measurements. Molecular integrity, alkyl chain ordering and wettability were evaluated for both elaborated coatings. The panel of characterization tools used demonstrates the efficient grafting of phosphonic acid compounds on oxidized copper surfaces. The grafting mode appears similar for both investigated molecules and is evaluated as a tridentate mode.

Fonder, Grégory; Minet, Isabelle; Volcke, Cédric; Devillers, Sébastien; Delhalle, Joseph; Mekhalif, Zineb

2011-05-01

314

Mechanical durability of superhydrophobic and oleophobic copper meshes  

NASA Astrophysics Data System (ADS)

We developed a simple and inexpensive method to prepare the superhydrophobic and oleophobic copper meshes with rough structures fabrication and chemical modification. The achieved surfaces displayed liquid-repellent toward water and several organic liquids (such as hexadecane), which possessed much lower surface tension than that of water. Liquid repellency of the fabricated superhydrophobic copper mesh was demonstrated by visible experiment results and contact angle measurements. Even if the superhydrophobic copper mesh was rolled up, it still kept the superhydrophobicity. The mechanical durability was investigated by finger touch and mechanical abrasion tests. The results indicated that the copper mesh can maintain its superhydrophobicity against an abrasion length of 300 cm under a high pressure (77.2 kPa). The superhydrophobicity and oleophobicity, combined with mechanical durability, would promote the superhydrophobic surface to practical application in industry in the future.

Yin, Linting; Yang, Jin; Tang, Yongcai; Chen, Lin; Liu, Can; Tang, Hua; Li, Changsheng

2014-10-01

315

COPPER RESEARCH UPDATE  

EPA Science Inventory

This presentation provides an update and overview of new research results and remaining research needs with respect to copper corrosion control issues. The topics to be covered include: occurrence of elevated copper release in systems that meet the Action Level; impact of water c...

316

SERUM COPPER IN ALZHEIMER  

Microsoft Academic Search

Abnormalities in the homeostasis of brain metals in Alzheimer's disease (AD) can contribute to set up environmental conditions where ß-amyloid toxicity and deposition are promoted within areas at risk. Recent studies in man have described possible implications of copper in the AD pathogenesis. In particular, evidence collected in our laboratory in the past six years shows that abnormalities in copper

R. SQUITTI; P. M. ROSSINI

2007-01-01

317

SO2 REMOVAL FROM FLUE GASES USING UTILITY SYNTHESIZED ZEOLITES  

SciTech Connect

It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO{sub 2} from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO{sub 2} from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150 C contained a greater proportion of zeolite and as such were more SO{sub 2} adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. 100 C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO{sub 2} adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the US.

Michael Grutzeck

1999-04-30

318

SO2 REMOVAL FROM FLUE GASES USING UTILITY SYNTHESIZED ZEOLITES  

SciTech Connect

It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO2 from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO2 from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150°C contained a greater proportion of zeolite and as such were more SO2 adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. _100°C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with other fly ashes, ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO2 adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the country.

MICHAEL GRUTZECK

1998-10-31

319

A high acid mesoporous USY zeolite prepared by alumination  

NASA Astrophysics Data System (ADS)

A high-acidity HUSY zeolite with mesoporous structure was prepared by alumination with a dilute aqueous NaAlO2 solution and characterized by XRD, N2 adsorption, IR framework vibration and 29Si MAS NMR methods. The results indicated the extra-framework aluminum was reinserted into the tetrahedral framework through isomorphic substitution of framework Si (0Al) sites by Al ions, whereas the crystal and micropore structure were unaltered. FTIR spectra of hydroxyl vibrations and pyridine adsorbed on realuminated zeolites showed that the number of Brønsted acid sites and strong Lewis acid sites increased whereas weak Lewis acid sites decreased twice. The mesoporous structure composed of inter-and intra-crystalline pores in the aluminated HUSY increased the external surface area of the zeolite, improving accessibility of molecules to the active sites and enhancing its catalytic ability. The realuminated HUSY zeolite supported with Ru catalyst exhibited a higher catalytic activity for benzene hydrogenation than the parent HUSY zeolite; the reaction rate in comparison to the mesozeolite increased by 5.5 times.

Ma, Jinghong; Kang, Yuhong; Ma, Ning; Hao, Wenming; Wang, Yan; Li, Ruifeng

2013-01-01

320

Ion exchangers in radioactive waste management: natural Iranian zeolites.  

PubMed

Five samples of natural zeolites from different parts of Iran were chosen for this study. In order to characterize and determine their structures, X-ray diffraction and infrared spectrometry were carried out for each sample. The selective absorption properties of each zeolite were found by calculating the distribution coefficient (K(d)) of various simulated wastes which were prepared by spiking the radionuclides with (131)I, (99)Mo, (153)Sm, (140)La and (147)Nd. All the zeolite samples used in this study had extremely high absorption value towards (140)La; clinoptolite from Mianeh and analsite from Ghalehkhargoshi showed good absorption for (147)Nd; clinoptolite from Semnan and clinoptolite from Firozkoh showed high absorption for (153)Sm; mesolite from Arababad Tabas showed good absorption for (99)Mo; and finally mesolite from Arababad Tabas, clinoptolite from Semnan and clinoptolite from Firozkoh could be used to selectively absorb (131)I from the stimulated waste which was prepared. The natural zeolites chosen for these studies show a similar pattern to those synthetic ion exchangers in the literature and in some cases an extremely high selectivity towards certain radioactive elements. Hence the binary separation of radioactive elements could easily be carried out. Furthermore, these zeolites, which are naturally occurring ion exchangers, are viable economically and extremely useful alternatives in this industry. PMID:16099667

Nilchi, A; Maalek, B; Khanchi, A; Ghanadi Maragheh, M; Bagheri, A; Savoji, K

2006-01-01

321

Phenol removal from wastewater by adsorption on zeolitic composite.  

PubMed

It is well known that adsorption is an efficient method of removal of various pollutants from wastewater. The present study examines the phenol removal from water by adsorption on a new material, based on zeolitic volcanic tuff. This compound contains zeolitic tuff and cellulose, another known adsorbent, in a mass ratio of 4 to 1. The performances of the new adsorbent composite were compared with those of a widely used adsorbent material, zeolitic volcanic tuff. The adsorbent properties were tested on batch synthetic solutions containing 1-10 mg L(-1) (1-10 ppm) phenol, at room temperature without pH adjustment. The influence of the adsorbent dose, pH and contact time on the removal degree of phenol from water was investigated. The experimental data were modeled using the Langmuir, Freundlich, and Temkin adsorption isotherms. The Langmuir model was found to best represent our data revealing a monolayer adsorption with a maximum adsorption capacity between 0.12 and 0.53 mg g(-1) at 25 °C, for 2.00 g of adsorbent, depending on the initial phenol concentration. The adsorption kinetic study was performed using a pseudo-first- and pseudo-second-order kinetic models illustrating that phenol adsorption on zeolite composite is well described by pseudo-first kinetic equations. Our results indicated that phenol adsorption on the new adsorbent composite is superior to that on the classic zeolite. PMID:23589237

Bizerea Spiridon, Otilia; Preda, Elena; Botez, Alexandru; Pitulice, Laura

2013-09-01

322

1,2,4-Trimethylbenzene Transformation Reaction Compared with its Transalkylation Reaction with Toluene over USY Zeolite Catalyst  

E-print Network

with Toluene over USY Zeolite Catalyst Sulaiman Al-Khattaf,* Nasir M. Tukur, and Adnan Al-Amer Chemical,2,4-Trimethylbenzene (TMB) transalkylation with toluene has been studied over USY zeolite type catalyst using a riser by Mobil-CPC.1,2 Zeolites such as Y, zeolite beta, and modernite possess a pore size large enough

Al-Khattaf, Sulaiman

323

Catalysis Letters 51 (1998) 1522 15 The role of acid sites in cobalt zeolite catalysts for selective  

E-print Network

Catalysis Letters 51 (1998) 15­22 15 The role of acid sites in cobalt zeolite catalysts Received 13 August 1997; accepted 9 January 1998 The role of the acidic support in ion-exchanged cobalt-zeolite acidic zeolites [4,10,15­17], such as ZSM-5 and morden- ite, the role of zeolite remains unclear [3

Regalbuto, John R.

324

Cysteine functionalized copper organosol: synthesis, characterization and catalytic application  

NASA Astrophysics Data System (ADS)

We herein report a facile one-pot synthesis, stabilization, redispersion and Cu-S interaction of L-cysteine and dodecanethiol (DDT) protected copper organosol in toluene from precursor copper stearate using sodium borohydride in toluene under a nitrogen atmosphere. Surface modification of the synthesized copper organosol with an amino acid L-cysteine and an alkanethiol (dodecanethiol, DDT) is accomplished by a thiolate bond between the used ligands and nanoparticle surface. The cysteine molecule binds the copper surface via a thiolate and amine linkage but not through electrostatic interaction with the carboxylate group due to the solvent polarity and dielectric medium. Fourier transform infrared (FTIR) analysis was performed to confirm the surface functionalization of the amino acid and DDT to the copper surface. Copper organosol has been characterized by optical spectroscopy (UV/vis), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The as-synthesized particles are spherical in shape and exhibit a Mie scattering profile with an absorption maxima in the visible range. Copper nanoparticles capped by cysteine and/or DDT in non-aqueous media are found to represent an interesting catalytic approach for the synthesis of octylphenyl ether.

Panigrahi, Sudipa; Kundu, Subrata; Basu, Soumen; Praharaj, Snigdhamayee; Jana, Subhra; Pande, Surojit; Ghosh, Sujit Kumar; Pal, Anjali; Pal, Tarasankar

2006-11-01

325

Space charge suppression induced by deep traps in polyethylene/zeolite nanocomposite  

NASA Astrophysics Data System (ADS)

NaY zeolite nanoparticles doped in low-density polyethylene (LDPE) is investigated. The zeolite nanoparticles are uniformly distributed in LDPE. Space charge distribution from pulsed electro-acoustic method and trap level from thermally stimulated current test are obtained. The results indicate that zeolite doping enormously suppresses space charge accumulation and reduces the conduction current by importing abundant deep traps. It can be explained that the zeolite nanoparticles increase the interface regions and introduce small size cavity traps from the porous surface of zeolite. The deep traps greatly weaken impurity ionization and carrier mobility, and raise potential barrier for charge injection.

Han, Bai; Wang, Xuan; Sun, Zhi; Yang, Jiaming; Lei, Qingquan

2013-01-01

326

Catalytic pyrolysis using UZM-39 aluminosilicate zeolite  

DOEpatents

A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and shown to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub.1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

Nicholas, Christopher P; Boldingh, Edwin P

2014-10-07

327

Catalytic pyrolysis using UZM-39 aluminosilicate zeolite  

DOEpatents

A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and show to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hyrdocarbons into hydrocarbons removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

Nicholas, Christpher P; Boldingh, Edwin P

2013-12-17

328

Modeling and Analysis on Pervaporation Separation of Composite Zeolite Membranes  

NASA Astrophysics Data System (ADS)

Pervaporation is a membrane separation technology that has had industrial application and which is the subject of ongoing research. Two major factors are important in judging the quality of a membrane: selectivity and permeation flux. Although many types of materials can be used for the separation layer, zeolites will be the material considered in this thesis. A simple mathematical model has been developed to demonstrate the inter-relationships between relative permeation flux, reduced selectivity, and the relative resistance to mass transfer of the support to the zeolite layer. The model was applied to several membranes from our laboratory and to two examples from the literature. The model offers a useful way of conceptualizing membrane performance and facilitates the comparison of different membrane performances. The model predicts the effect of different supports on zeolite supported membrane performance.

Mann, Stewart

329

The environmental applications of activated carbon/zeolite composite materials.  

PubMed

Over the past couple of years, the resurgence of placing an effective and sustainable amendment to combat against the auxiliary industrial entities, remains a highly contested agenda from a global point. With the renaissance of activated carbon, there has been a steadily growing interest in the research field. Recently, the adoption of zeolite composite, a prestigious advanced catalyst which formulates the enhancement of adsorption rate and hydrogen storage capability, has fore fronted to be a new growing branch in the scientific community. Confirming the assertion, this paper presents a state of art review of activated carbon/zeolite composite technology, its fundamental background studies, and environmental implications. Moreover, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbon/zeolite composite represents a potentially viable and powerful tool, leading to the plausible improvement of environmental preservation. PMID:21035101

Foo, K Y; Hameed, B H

2011-02-17

330

Computer simulations of benzene in faujasite-type zeolites  

SciTech Connect

The exact nature of the cation-benzene ring interaction is not yet known. In order to remedy this, energy minimization and Monte Carlo methods were used to probe the location and energetics of benzene in sodium zeolite-X and -Y. Sorption energies for the six-ring binding site in each of the zeolite models with the two forcefields (cff91 and cvff) are tabulated as function of Si/Al ratio. Both forcefields predict similar binding sites for each system; however, the final energies are sensitive to form and parameterization of the forcefield. Further work is needed to refine the forcefield for zeolite-sorbate interactions. 5 figs, 21 refs, 2 tabs.

Henson, N.J.; Cheetham, A.K. [California Univ., Santa Barbara, CA (United States). Dept. of Materials; Redondo, A. [Los Alamos National Lab., NM (United States); Levine, S.M.; Newsam, J.M. [Biosym Technologies Inc., San Diego, CA (United States)

1994-03-01

331

Ring opening of methylcyclohexane over platinum-loaded zeolites.  

PubMed

The activity of different platinum-loaded zeolites (Mordenite, ZSM-12, ZSM-5, ZSM-23) was investigated in the hydroconversion of methylcyclohexane (MCH), in the context of upgrading highly aromatic distillates for fuel blending. In all cases, conversion of MCH proceeds according to a pathway where the primary products are a mixture of dimethylcyclopentanes and ethylcyclopentane formed by isomerization and ring contraction of MCH. The primary products undergo consecutive ring-opening reactions with formation of n- and isoheptanes. The latter further react to form lower-molecular-weight n- and isoalkanes. The selectivity and distribution of products deriving from ring-contraction and ring-opening reactions are strongly affected by the pore size and topology of the zeolites. ZSM-5 exhibits a strong reactant shape-selectivity effect on ring-opening products. The evaluated zeolites show the following order of activity in the conversion of methylcyclohexane: Mordenite>ZSM-12>ZSM-5>ZSM-23. PMID:18702154

Calemma, Vincenzo; Carati, Angela; Flego, Cristina; Giardino, Roberto; Gagliardi, Federica; Millini, Roberto; Bellussi, Giuseppe

2008-01-01

332

Optical spectra of noble metal nanoparticles supported on zeolites  

NASA Astrophysics Data System (ADS)

Optical spectra of noble metal nano-particles supported on different types of zeolites are studied and compared. The absorbance spectra of Cu, Ag and Au nanoparticles supported on mordenite, ?-zeolite, Na/Y and H/Y zeolites respectively are reported. Spectra for pre-exchanged Au-Cu/Na/Y, Au-Ni/Na/Y and Au-Fe/Na/Y are also studied. A simple effective medium approach (Maxwell-Garnett) is used to obtain a theoretical complex effective dielectric function of the composite and to asses the sensibility of the plasmon resonance to the sample characteristics. The knowledge of these properties can hopefully be applied to the development of optical tools to monitor the synthetic path.

López Bastidas, Catalina; Smolentseva, Elena; Machorro, Roberto; Petranovskii, Vitalii

2014-09-01

333

Coherent X-ray Diffraction Imaging of Zeolite Microcrystals  

SciTech Connect

We measured coherent x-ray diffraction (CXD), an emerging technique to obtain three-dimensional internal and external images of crystals, on ZSM-5 zeolite microcrystals to get internal density distribution and to map deformation field of strain. The experiments were performed at the beamline 34-ID-C in Advanced Photon Source at Argonne National Laboratory in the US. The CXD patterns of ZSM-5 zeolite microcrystals with sizes of 2 {mu}m by monochromatic coherent x-rays with energy of 9 keV were obtained under continuously surrounding and Bragg conditions as a function of temperature. The oversampled diffraction patterns are inverted to obtain three-dimensional images of the shapes and internal strain fields of zeolite microcrystals using phase retrieval algorithms of error reduction and a hybrid input-output method. The internal density and strain distribution as a function of temperature are discussed.

Cha, Wonsuk; Song, Sanghoon; Kim, Hyunjung [Department of Physics and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul (Korea, Republic of); Jeong, Nak Cheon; Yoon, Kyung Byung [Department of Chemistry, Sogang University, Seoul (Korea, Republic of); Harder, Ross; Robinson, Ian K. [Department of Physics and Astronomy, University College London, London (United Kingdom)

2009-04-19

334

Coherent X-ray Diffraction Imaging of Zeolite Microcrystals (abstract)  

NASA Astrophysics Data System (ADS)

We measured coherent x-ray diffraction (CXD), an emerging technique to obtain three-dimensional internal and external images of crystals, on ZSM-5 zeolite microcrystals to get internal density distribution and to map deformation field of strain. The experiments were performed at the beamline 34-ID-C in Advanced Photon Source at Argonne National Laboratory in the US. The CXD patterns of ZSM-5 zeolite microcrystals with sizes of 2 ?m by monochromatic coherent x-rays with energy of 9 keV were obtained under continuously surrounding and Bragg conditions as a function of temperature. The oversampled diffraction patterns are inverted to obtain three-dimensional images of the shapes and internal strain fields of zeolite microcrystals using phase retrieval algorithms of error reduction and a hybrid input-output method. The internal density and strain distribution as a function of temperature are discussed.

Cha, Wonsuk; Song, Sanghoon; Jeong, Nak Cheon; Yoon, Kyung Byung; Harder, Ross; Robinson, Ian K.; Kim, Hyunjung

2009-04-01

335

Synthesis of self-pillared zeolite nanosheets by repetitive branching.  

PubMed

Hierarchical zeolites are a class of microporous catalysts and adsorbents that also contain mesopores, which allow for fast transport of bulky molecules and thereby enable improved performance in petrochemical and biomass processing. We used repetitive branching during one-step hydrothermal crystal growth to synthesize a new hierarchical zeolite made of orthogonally connected microporous nanosheets. The nanosheets are 2 nanometers thick and contain a network of 0.5-nanometer micropores. The house-of-cards arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites. PMID:22745424

Zhang, Xueyi; Liu, Dongxia; Xu, Dandan; Asahina, Shunsuke; Cychosz, Katie A; Agrawal, Kumar Varoon; Al Wahedi, Yasser; Bhan, Aditya; Al Hashimi, Saleh; Terasaki, Osamu; Thommes, Matthias; Tsapatsis, Michael

2012-06-29

336

Safe trapping of Cs in heat-treated zeolite matrices  

NASA Astrophysics Data System (ADS)

Cesium retention performances of two different natural zeolites (an Italian phillipsite-rich tuff and a Mexican erionite-rich tuff), pre-exchanged in Cs form and heat-treated, are compared. After thermal treatment at 1000 °C both zeolites satisfactorily retain Cs during back-exchange tests with NaCl solution or by a prolonged contact with distilled water. The different mechanisms of Cs encapsulation are elucidated. The Cs-exchanged phillipsite, a less siliceous and less heat-stable zeolite, tends to form pollucite on heating. Pollucite is a naturally occurring mineral phase which contains and irreversibly traps cesium. The Cs-exchanged erionite tends to form an amorphous phase on heating and Cs is immobilized through glass formation.

Bosch, P.; Caputo, D.; Liguori, B.; Colella, C.

2004-01-01

337

Intracellular copper routing: the role of copper chaperones.  

PubMed

Copper is required by all living systems. Cells have a variety of mechanisms to deal with this essential, yet toxic trace element. A recently discovered facet of homeostatic mechanisms is the protein-mediated, intracellular delivery of copper to target proteins. This routing is accomplished by a novel class of proteins, the 'copper chaperones'. They are a family of conserved proteins present in prokaryotes and eukaryotes, which suggests that copper chaperones are used throughout nature for intracellular copper routing. PMID:10637610

Harrison, M D; Jones, C E; Solioz, M; Dameron, C T

2000-01-01

338

Influence of Crystal Expansion/Contraction on Zeolite Membrane Permeation  

SciTech Connect

X-ray diffraction was used to measure the unit cell parameters of B-ZSM-5, SAPO-34, and NaA zeolite powders as a function of adsorbate loading at 303 K, and in one case, at elevated temperatures. Most adsorbates expanded the zeolite crystals below saturation loading at 303 K: n-hexane and SF6 in B-ZSM-5, methanol and CO2 in SAPO-34, and methanol in NaA zeolite. As the loadings increased, the crystals expanded more. Changes in the unit cell volumes of B-ZSM-5 and SAPO-34 zeolite powders correlated with changes in permeation through zeolite membranes defects. When the zeolite crystals expanded or contracted upon adsorption, the defect sizes decreased or increased. In B-ZSM-5 membranes, the fluxes through defects decreased dramatically when n-hexane or SF6 adsorbed. In contrast, i-butane adsorption at 303 K contracted B-ZSM-5 crystals at low loadings and expanded them at higher loadings. Correspondingly, the flux through B-ZSM-5 membrane defects increased at low i-butane loadings and decreased at high loading because the defects increased in size at low loading and decreased at high loadings. At 398 K and 473 K, n-hexane expanded the B-ZSM-5 unit cell more as the temperature increased from 303 to 473 K. The silicalite-1 and B-ZSM-5 unit cell volumes expanded similarly upon n-hexane adsorption at 303 K; boron substitution had little effect on volume expansion.

Sorenson, Stephanie G [University of Colorado, Boulder; Payzant, E Andrew [ORNL; Noble, Richard D [University of Colorado, Boulder; Falconer, John L. [University of Colorado, Boulder

2010-01-01

339

Copper tolerance in Silene cucubalus  

Microsoft Academic Search

The uptake, translocation and subcellular distribution of copper as well as its effect on chloroplasts and plastocyanin synthesis were studied in a copper-sensitive and a copper-tolerant population of Silene cucubalus (L.) Wib. As a function of time, the copper concentration in roots of tolerant plants increased more slowly than that in roots of sensitive ones. Translocation to the shoot occurred

P. C. Lolkema; R. Vooijs

1986-01-01

340

Effects of TS1 zeolite structures on physical properties and enzymatic degradation of Poly (butylene succinate) (PBS)\\/TS1 zeolite hybrid composites  

Microsoft Academic Search

The objective of this study was to investigate how the water uptake features and carrier characteristics of the TS-1 zeolite affected the physical and rheological properties, morphological parameters, and enzymatic hydrolysis of Poly (butylene succinate) (PBS). The introduction of TS-1 zeolite as catalyst was developed for the preparation of PBS\\/TS-1 zeolite hybrid composites (PTHC) without heavy metal toxic substance in

Sung Yeon Hwang; Eui Sang Yoo; Seung Soon Im

2011-01-01

341

Solvent-free synthesis of zeolites from anhydrous starting raw solids.  

PubMed

Development of sustainable routes for synthesis of zeolites is very important because of wide applications of zeolites at large scale in the fields of catalysis, adsorption, and separation. Here we report a novel and generalized route for synthesis of zeolites in the presence of NH4F from grinding the anhydrous starting solid materials and heating at 140-240 °C. Accordingly, zeolites of MFI, BEA*, EUO, and TON structures have been successfully synthesized. The presence of F(-) drives the crystallization of these zeolites from amorphous phase. Compared with conventional hydrothermal synthesis, the synthesis in this work not only simplifies the synthesis process but also significantly enhances the zeolite yields. These features should be potentially of great importance for industrial production of zeolites at large scale in the future. PMID:25574592

Wu, Qinming; Liu, Xiaolong; Zhu, Longfeng; Ding, Lihong; Gao, Pan; Wang, Xiong; Pan, Shuxiang; Bian, Chaoqun; Meng, Xiangju; Xu, Jun; Deng, Feng; Maurer, Stefan; Müller, Ulrich; Xiao, Feng-Shou

2015-01-28

342

COPPER CABLE RECYCLING TECHNOLOGY  

SciTech Connect

The United States Department of Energy (DOE) continually seeks safer and more cost-effective technologies for use in deactivation and decommissioning (D&D) of nuclear facilities. The Deactivation and Decommissioning Focus Area (DDFA) of the DOE's Office of Science and Technology (OST) sponsors large-scale demonstration and deployment projects (LSDDPs). At these LSDDPs, developers and vendors of improved or innovative technologies showcase products that are potentially beneficial to the DOE's projects and to others in the D&D community. Benefits sought include decreased health and safety risks to personnel and the environment, increased productivity, and decreased costs of operation. The Idaho National Engineering and Environmental Laboratory (INEEL) generated a list of statements defining specific needs and problems where improved technology could be incorporated into ongoing D&D tasks. One such need is to reduce the volume of waste copper wire and cable generated by D&D. Deactivation and decommissioning activities of nuclear facilities generates hundreds of tons of contaminated copper cable, which are sent to radioactive waste disposal sites. The Copper Cable Recycling Technology separates the clean copper from contaminated insulation and dust materials in these cables. The recovered copper can then be reclaimed and, more importantly, landfill disposal volumes can be reduced. The existing baseline technology for disposing radioactively contaminated cables is to package the cables in wooden storage boxes and dispose of the cables in radioactive waste disposal sites. The Copper Cable Recycling Technology is applicable to facility decommissioning projects at many Department of Energy (DOE) nuclear facilities and commercial nuclear power plants undergoing decommissioning activities. The INEEL Copper Cable Recycling Technology Demonstration investigated the effectiveness and efficiency to recycle 13.5 tons of copper cable. To determine the effectiveness of separating out radioactive contamination, the copper cable was coated with a surrogate contaminant. The demonstration took place at the Bonneville County Technology Center in Idaho Falls, Idaho.

Chelsea Hubbard

2001-05-01

343

CO2 adsorption on LTA zeolites: Effect of mesoporosity  

NASA Astrophysics Data System (ADS)

Highly mesoporous LTA zeolite (Meso-LTA) was prepared using an organosilane surfactant, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, as a mesopore-generating agent. Meso-LTA was characterized by X-ray powder diffraction, N2 adsorption-desorption isotherm at 77 K, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, and then investigated for CO2 adsorption at 298 K. Compared to a solely microporous LTA zeolite (Micro-LTA), Meso-LTA showed faster CO2 adsorption kinetics at 1 bar and higher CO2 adsorption capacities under high pressure conditions (>10 bar).

Chen, Chao; Ahn, Wha-Seung

2014-08-01

344

Zeolites replacing plant fossils in the Denver formation, Lakewood, Colorado.  

USGS Publications Warehouse

Well-developed crystals of heulandite and stilbite, within fossil wood, occur in sedimentary rocks in Lakewood, Jefferson County. The rocks belong to the Denver formation, a locally fossiliferous deposit of fluvial claystone, siltstone, sandstone and conglomerate, containing some volcanic mudflows (andesitic) of late Cretaceous to Palaeocene age. Altered volcanic glass released Na and Ca into the ground-water and subsequently zeolites were crystallized in the open spaces between grains and within fossil plant structures. Minor pyrite, quartz (jasper), calcite and apatite also occur as replacements of fossil wood. Similar zeolite occurrences in other areas are reviewed.-R.S.M.

Modreski, P.J.; Verbeek, E.R.; Grout, M.A.

1984-01-01

345

Computer simulation of Xe adsorption in zeolite Y  

SciTech Connect

Computer modeling of fluids in zeolites can provide a detailed molecular level understanding of the process of adsorption and diffusion under the influence of the 3-D potential field and the confinement offered by the crystal structure. The authors have shown that there is a strong link between the location, geometry and energetics of sites and the observed thermodynamics and spectroscopy of the adsorbates. Here they report on the modeling of Xe in zeolite Y, which is of interest both because it is commercially important and because it offers two distinct adsorption sites.

Gupta, V.; Davis, H.T.; McCormick, A.V. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science

1996-12-31

346

Method for encapsulating nanoparticles in a zeolite matrix  

DOEpatents

A method for preparing a metal nanocluster composite material. A porous zeolitic material is treated with an aqueous metal compound solution to form a metal ion-exchanged zeolitic material, heated at a temperature ramp rate of less than 2.degree. C./min to an elevated temperature, cooled, contacted with an organic monomer and heating to induce polymerization, and heating the composite material to greater than 350.degree. C. under non-oxidizing conditions to form a metal nanocluster-carbon composite material with nanocluster sizes between approximately 0.6 nm and 10 nm.

Coker, Eric N. (Albuquerque, NM)

2007-12-11

347

Acid-site distribution on Faujasite-type zeolites determined by n-butylamine titration--1. Comparison of the use of hammett and arylmethanol indicators on zeolites X  

SciTech Connect

The combined Lewis and Broensted acidities were measured of 13X (sodium) zeolite and of its 84.2% calcium-exchanged, 86.0% lanthanum-exchanged, and 69.2% protonated forms, calcined at 400/sup 0/C. The butylamine titrations were performed to visible color changes of Hammett indicators. The H/sub 0/ acidities were 0 for the sodium X zeolite, and 0.2, 0.98, and 0.75 for the calcium, lanthanum, and hydrogen zeolites, respectively. These acidities compared well with trends reported in literature for zeolites pretreated under different conditions. Titration of Broensted sites with arylmethanol indicators did not give satisfactory visible endpoints.

Atkinson, D.; Curthoys, G.

1980-05-29

348

The growth of zeolites A, X and mordenite in space  

NASA Technical Reports Server (NTRS)

Zeolites are a class of crystalline aluminosilicate materials that form the backbone of the chemical process industry worldwide. They are used primarily as adsorbents and catalysts and support to a significant extent the positive balance of trade realized by the chemical industry in the United States (around $19 billion in 1991). The magnitude of their efforts can be appreciated when one realizes that since their introduction as 'cracking catalysts' in the early 1960's, they have saved the equivalent of 60 percent of the total oil production from Alaska's North Slope. Thus the performance of zeolite catalysts can have a profound effect on the U.S. economy. It is estimated that a 1 percent increase in yield of the gasoline fraction per barrel of oil would represent a savings of 22 million barrels of crude oil per year, representing a reduction of $400 million in the United States' balance of payments. Thus any activity that results in improvement in zeolite catalyst performance is of significant scientific and industrial interest. In addition, due to their 'stability,' uniformity, and, within limits, their 'engineerable' structures, zeolites are being tested as potential adsorbents to purify gases and liquids at the parts-per-billion levels needed in today's electronic, biomedical, and biotechnology industries and for the environment. Other exotic applications, such as host materials for quantum-confined semiconductor atomic arrays, are also being investigated. Because of the importance of this class of material, extensive efforts have been made to characterize their structures and to understand their nucleation and growth mechanisms, so as to be able to custom-make zeolites for a desired application. To date, both the nucleation mechanics and chemistry (such as what are the 'key' nutrients) are, as yet, still unknown for many, if not all, systems. The problem is compounded because there is usually a 'gel' phase present that is assumed to control the degree of supersaturation, and this gel undergoes a continuous 'polymerization' type reaction during nucleation and growth. Generally, for structure characterization and diffusion studies, which are useful in evaluating zeolites for improving yield in petroleum refining as well as for many of the proposed new applications (e.g., catalytic membranes, molecular electronics, chemical sensors) large zeolites (greater than 100 to 1000 times normal size) with minimum lattice defects are desired. Presently, the lack of understanding of zeolite nucleation and growth precludes the custom design of zeolites for these or other uses. It was hypothesized that the microgravity levels achieved in an orbiting spacecraft could help to isolate the possible effects of natural convection (which affects defect formation) and minimize sedimentation, which occurs since zeolites are twice as dense as the solution from which they are formed. This was expected to promote larger crystals by allowing growing crystals a longer residence time in a high-concentration nutrient field. Thus it was hypothesized that the microgravity environment of Earth orbit would allow the growth of large, more defect-free zeolite crystals in high yield.

Sacco, Albert, Jr.; Bac, N.; Coker, E. N.; Dixon, A. G.; Warzywoda, J.; Thompson, R. W.

1994-01-01

349

Volatility of copper  

SciTech Connect

The relevant aqueous thermodynamics of copper and its oxides are evaluated and summarized with emphasis on solubility, hydrolysis, and complexation. The solubilities of metallic copper, solid cuprous and cupric oxides in steam measured by Pocock and Stewart in 1963 are discussed and the latter data are fitted in the form of established empirical equations and compared to other existing results. No other sources of data were found for the solubility of copper and cupric oxide in steam and even these data are very limited. Discussion of corresponding available solubility data on both oxide phases in liquid water is given. The possible effects of complexing agents are considered. A brief discussion is provided of the role of surface adsorption in determining the fate of dissolved copper in the boiler. 37 refs., 5 figs., 3 tabs.

Palmer, D.A.; Simonson, J.M.; Joyce, D.B.

1996-08-01

350

Modification of acid sites in ZSM-5 by ion-exchange: An in-situ FTIR study  

NASA Astrophysics Data System (ADS)

A study of the acid sites in Mn+-ZSM-5 zeolites (Mn+ = H+, Al3+, Ca2+, and Ba2+), synthesized by ion-exchange from the NH4+ form, has been carried out using X-ray diffraction, 27Al MAS NMR, and in-situ FTIR spectroscopy. X-ray diffraction data indicate that the crystalline structure of ZSM-5 is maintained on ion-exchange. 27Al MAS NMR spectroscopy confirms that Lewis acid sites in all of the Mn+-ZSM-5 zeolites are mainly located on the tetrahedral aluminum atoms in the zeolite framework. However, octahedral extra-framework aluminum is another source of Lewis acid sites in H+-ZSM-5 and Al3+-ZSM-5. Brønsted acid sites are identified as originating from the hydroxyl groups that bridge Al and Si atoms. The acid sites in Mn+-ZSM-5 have been characterized by in-situ FTIR spectroscopy with pyridine as the probe molecule. FTIR spectroscopy demonstrated that the number of accessible acid sites and ratio of Lewis to Brønsted acid sites in Mn+-ZSM-5 can be effectively modified by ion-exchange. The number of acid sites in Mn+-ZSM-5 increases in the same order as the acidity of cations with Ba2+ < Ca2+ < NH4+ < Al3+ < H+. Though the strength of both Lewis and Brønsted acid sites is virtually identical for all Mn+-ZSM-5 zeolites, the ratio of Brønsted to Lewis acid sites varies as a result of the loaded cation. In addition, modification of acid sites in Mn+-ZMS-5 by loading different cations is discussed in terms of the accessibility of the surface of the zeolite channels and the reactivity of the cations with Brønsted acid hydroxyls. We conclude that larger cations can effectively constrict the zeolite channels and impede the ability of pyridine to access acid sites on the surface of the channels.

Wu, Weiqiang; Weitz, Eric

2014-10-01

351

Copper tolerance and copper accumulation of herbaceous plants colonizing inactive California copper mines  

SciTech Connect

Herbaceous plant species colonizing four copper mine waste sites in northern California were investigated for copper tolerance and copper accumulation. Copper tolerance was found in plant species colonizing soils with high concentrations of soil copper. Seven of the eight plant species tested were found at more than one copper mine. The mines are geographically isolated, which makes dispersal of seeds from one mine to another unlikely. Tolerance has probably evolved independently at each site. The nontolerant field control population of Vulpia microstachya displays significantly higher tolerance to copper at all copper concentration levels tested than the nontolerant Vulpia myrous population, and the degree of copper tolerance attained by V. microstachya at the two copper mines was much greater than that found in V. myrous. It suggests that even in these two closely related species, the innate tolerance in their nontolerant populations may reflect their potential for evolution of copper tolerance and their ability to initially colonize copper mine waste sites. The shoot tissue of the copper mine plants of Arenaria douglasii, Bromous mollis, and V. microstachya accumulated less copper than those plants of the same species from the field control sites when the two were grown in identical conditions in nutrient solution containing copper. The root tissue of these mine plants contain more copper than the roots of the nonmine plants. This result suggests that exclusion of copper from the shoots, in part by immobilization in the roots, may be a feature of copper tolerance. No difference in the tissue copper concentration was detected between tolerant and nontolerant plants of Lotus purshianus, Lupinus bicolor, and Trifolium pratense even though the root tissue had more copper than the leaves.

Kruckeberg, A.L.; Wu, L. (Department of Environmental Horticulture, University of California, Davis (United States))

1992-06-01

352

The influence of chemisorbed molecules on mass transfer in H-ZSM-5-type zeolites and the location of Broensted acid sites  

SciTech Connect

Heterogeneous catalysis is one of the most important applications of zeolites. Therefore, various methods have been developed to determine the strength and concentration of Bronsted acid sites in zeolites. Among them, in the last few years, {sup 1}H MAS NMR has become a powerful tool. In addition to the accessibility of the acid sites probed by chemisorption of N-bases, the steric environment of these catalytically active sites is of importance since it imposes constraints on the geometry of the transition state. However, only a few studies have been reported on this topic. Information was obtained from quantum chemical calculations, catalytic experiments, I.R. spectroscopy, and the arrangement of guest molecules. From these investigations it has been concluded that in H-ZSM-5 the channel intersections should be preferential location centers for the Bronsted acid sites. In adsorption technology, in the use of zeolites as shape-selective adsorbents, modification of the molecular sieve properties by chemisorption of nitrogen-containing bases (N-compounds) has become a common technique. The authors have applied the NMR pulsed field gradient technique to study the influence of chemisorbed N-compounds on transport properties of molecular sieves, considering the chemisorbed compounds as transport obstacles.

Caro, J.; Buelow, M. (Zentralinstitut fuer Physikalische Chemie der AdW der DDR, Berlin (Germany, F.R.)); Kaerger, J.; Pfeifer, H. (Karl-Marx-Universitaet, Leipzig (Germany, F.R.))

1988-11-01

353

Oxygen reactivity and formate structure in X zeolite  

Microsoft Academic Search

The i.r. absorption spectra of surface formate and gas phase decomposition products resulting from different surface reactions over basic FAU(X) zeolites have been compared. Based on these results a bridging surface formate species is proposed, which can account for the observed i.r. absorption data and different gas phase products.

M. Rep; J. G. van Ommen; L. Lefferts; J. A. Lercher

2004-01-01

354

Zeolite formation from coal fly ash and its adsorption potential  

SciTech Connect

The possibility in converting coal fly ash (CFA) to zeolite was evaluated. CFA samples from the local power plant in Prachinburi province, Thailand, were collected during a 3-month time span to account for the inconsistency of the CFA quality, and it was evident that the deviation of the quality of the raw material did not have significant effects on the synthesis. The zeolite product was found to be type X. The most suitable weight ratio of sodium hydroxide (NaOH) to CFA was approximately 2.25, because this gave reasonably high zeolite yield with good cation exchange capacity (CEC). The silica (Si)-to-aluminum (Al) molar ratio of 4.06 yielded the highest crystallinity level for zeolite X at 79% with a CEC of 240 meq/100 g and a surface area of 325 m{sup 2}/g. Optimal crystallization temperature and time were 90{sup o}C and 4 hr, respectively, which gave the highest CEC of approximately 305 meq/100 g. Yields obtained from all experiments were in the range of 50-72%. 29 refs., 5 tabs., 7 figs.

Duangkamol Ruen-ngam; Doungmanee Rungsuk; Ronbanchob Apiratikul; Prasert Pavasant [Chulalongkorn University, Bangkok (Thailand). Department of Chemical Engineering

2009-10-15

355

High-pressure alchemy on a small-pore zeolite  

NASA Astrophysics Data System (ADS)

While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

Lee, Y.

2011-12-01

356

Geopolymer synthesis using alkaline activation of natural zeolite  

Microsoft Academic Search

The influence of activator ratio, time, and curing temperature on the mechanical strength of geopolymers synthesized from natural zeolite was evaluated by employing silicate solutions and sodium hydroxide. The results demonstrated that an increase in the activator ratio as well as that of curing time favors mechanical strength in the material. Nevertheless, with 90day of curing time and 80°C or

C. Villa; E. T. Pecina; R. Torres; L. Gómez

2010-01-01

357

Fenton Chemistry of FeIII Zeolitic Minerals Treated with  

E-print Network

Fenton Chemistry of FeIII -Exchanged Zeolitic Minerals Treated with Antioxidants T O N I A . R U D Fenton activity. Lung lining fluid contains antioxidants, such as glutathione (GSH) and ascorbic acid (AA), which can reduce FeIII to FeII. In this study, we have compared the Fenton reactivity of Fe

Dutta, Prabir K.

358

Selective photooxidation of hydrocarbons in zeolites by oxygen  

DOEpatents

A selective photooxidation process for the conversion of hydrocarbon molecules to partially oxygenated derivatives, which comprises the steps of adsorbing a hydrocarbon and oxygen onto a dehydrated zeolite support matrix to form a hydrocarbon-oxygen contact pair, and subsequently exposing the hydrocarbon-oxygen contact pair to visible light, thereby forming a partially oxygenated derivative.

Frei, Heinz (Berkeley, CA); Blatter, Fritz (Berkeley, CA); Sun, Hai (Berkeley, CA)

1998-01-01

359

Studies of photochemically and electrochemically driven electron transport in zeolites  

NASA Astrophysics Data System (ADS)

Electron transfer reactions in zeolites and related solid-state materials are being studied. Some particular areas of study are: Electron transfer reactions of linked sensitizer-acceptor molecules. We have studied via laser flash photolysis transient absorbance the photochemistry of linked Ru(bpy)3--diquat molecules exchanged onto the outer surface of zeolite L powder. Electron-donor quenching of excited-state RuL3 complexes was also examined. We have studied electron transfer reactions between cyanometallate anions M(CN)8(sup 4 minus)(M = Mo,W), M(CN)6(sup 4 minus)(M = Fe,Os) and excited state ruthenium complexes. Quantum-size TiO2 in zeolite L was next examined. We are attempting to prepare systems in which the conduction band of an oxide semiconductor is used to convey electrons from a sensitizer to a catalyst within a zeolite L particle. Internal platinization of pillared clays. We have photoplatinized dispersed Na(+) montmorillonite, using PtCl6(sup 2 minus) as the platinum source, and then pillared the clay with Al(OH)2C1 solutions. We are currently investigating the size and charge selectivity of these catalytic materials.

Mallouk, T. E.

1988-04-01

360

Zeolite formation from coal fly ash and its adsorption potential.  

PubMed

The possibility in converting coal fly ash (CFA) to zeolite was evaluated. CFA samples from the local power plant in Prachinburi province, Thailand, were collected during a 3-month time span to account for the inconsistency of the CFA quality, and it was evident that the deviation of the quality of the raw material did not have significant effects on the synthesis. The zeolite product was found to be type X. The most suitable weight ratio of sodium hydroxide (NaOH) to CFA was approximately 2.25, because this gave reasonably high zeolite yield with good cation exchange capacity (CEC). The silica (Si)-to-aluminum (Al) molar ratio of 4.06 yielded the highest crystallinity level for zeolite X at 79% with a CEC of 240 meq/100 g and a surface area of 325 m2/g. Optimal crystallization temperature and time were 90 degrees C and 4 hr, respectively, which gave the highest CEC of approximately 305 meq/100 g. Yields obtained from all experiments were in the range of 50-72%. PMID:19842322

Ruen-ngam, Duangkamol; Rungsuk, Doungmanee; Apiratikul, Ronbanchob; Pavasant, Prasert

2009-10-01

361

Characterisation of zeolitic catalysts by the adsorption of molecular probes  

Microsoft Academic Search

Few examples of the characterisation by FTIR spectroscopy supplemented by the use of CO2, CO and NO molecular probes of acid, base and redox centres in zeolites (NaX and NaY) and zeolitetype (HSAPO-34, a silicon-aluminophosphate,\\u000a and CoAPO-18, a cobalt-aluminophosphate) catalysts, are illustrated.

S. Coluccia; L. Marchese; G. Martra

2000-01-01

362

Characterisation of the textural properties of chemically dealuminated Y zeolites  

Microsoft Academic Search

The main objective of this work is to characterise the textural properties of a series of Y zeolites dealuminated by ammonium hexafluorosilicate treatment. It was observed that the fluorosilicate treatment produced a highly crystalline product with a contracted unit cell. Both textural and XRD analysis confirmed the samples to be at least 95% crystalline for dealumination degrees ?50%. According to

R. López-Fonseca; B. de Rivas; J. I. Gutiérrez-Ortiz; J. R. González-Velasco

2002-01-01

363

[Denitrification water treatment with zeolite composite filter by intermittent operation].  

PubMed

The zeolite composite filters (ZCF) with the size of4-8 mm were prepared using raw zeolite (0.15-0.18 mm) as the main material and the cement as binder. After a combination of material characterizations, such as the void fraction, apparent density, compression strength and surface area, the optimal prepared conditions of composite filters were obtained as follow: weight ratio of m (zeolite): m (cement) = 7 : 3, curing for 15 d under the moisture condition and ambient temperature. Through upflow low-concentration ammonia nitrogen wastewater, ZCF filled in the experimental column was hung with the biological membrane. Thus, intermittent dynamic experiments were conducted, the intermittent operation cycle included adsorption, biological regeneration and drip washing. Until concentration of ammonia nitrogen was more than 2 mg x L(-1) of effluent standards, water in experiment column was firstly emptied, and then blast biological regeneration was conducted. After the filters were bathed with water, the zeolite adsorption-biological regeneration cycle was performed repeatedly. The experimental results show that under conditions of 24 h blast and 5 d of continuous operation period, ammonia nitrogen removal rate is up to 87.6% on average, total nitrogen removal rate reaches 51.2% on average. PMID:23379168

Qing, Cheng-Song; Bao, Tao; Chen, Tian-Hu; Chen, Dong; Xie, Jing-Jing

2012-12-01

364

Keggin anions promoted synthesis of zeolites and mesoporous materials  

Microsoft Academic Search

A rapid and convenient route to synthesize microporous (zeolites e.g. FAU, MFI and FER) and mesoporous (MCM-41 and MCM-48) materials employing Keggin anions as novel promoters has been reported. The catalytic use of these promoters not only reduces the syntheses time by 3 to 4 folds but also produces uniform and very small (nanosized) crystallites of the materials. Various Keggin

K. Mukhopadhyay; A. Ghosh; R. Kumar

2004-01-01

365

DIFFUSION MEASUREMENTS DURING PERVAPORATION THROUGH A ZEOLITE MEMBRANE  

EPA Science Inventory

An isotopic-transient technique was used to directly measure diffusion times of H2O, methanol, ethanol, 2-propanol, and acetone in pure and binary mixture feeds transporting through a zeolite membrane under steady-state pervaporation conditions. Diffusivities can be determ...

366

Synthesis of Na-zeolites from fly ash  

Microsoft Academic Search

The present study focuses on the synthesis of zeolites after fly ash activation, the major objectives being: (a) to study the activation processes; (b) to elucidate the activation conditions for maximum synthesis efficiency; (c) to optimize the conditions for the monomineral synthesis; and (d) to test synthesis efficiencies for different fly ash types. Fly ash was activated by NaOH and

Xavier Querol; Felicià Plana; Andrés Alastuey; Angel López-Soler

1997-01-01

367

Ammonium removal from wastewaters using natural New Zealand zeolites  

Microsoft Academic Search

Ammoniacal nitrogen (ammonia and ammonium) in agricultural wastewaters can promote eutrophication of receiving waters and be potentially toxic to fish and other aquatic life. Zeolites, which are hydrated aluminum?silicate minerals, have an affinity for ammonium ions (NH4 ) and are, therefore, potentially useful in removing this contaminant from wastewaters. The major objectives of this study were to evaluate the capacity

M. L. Nguyen; C. C. Tanner

1998-01-01

368

ADSORPTION AND CATALYTIC DESTRUCTION OF TRICHLOROETHYLENE IN HYDROPHOBIC ZEOLITES  

EPA Science Inventory

Several chromium exchanged ZSM-5 zeolites of varying SiO2/Al2O3 ratio were prepared and investigated for ambient (23 ?C) adsorption and subsequent oxidative destruction (250-400 ?C) of gaseous trichloroethylene (TCE, Cl2C=CHCl) in a humid air stream. With an increase in the SiO2...

369

ESCA studies of the surface chemistry of zeolites  

SciTech Connect

It has been demonstrated that the constituents on the surfaces of various pure zeolites, clays, silicas, and aluminas yield reproducible ESCA peaks with unique binding energies. The collective patterns realized by these different binding energies strongly suggest the registration of selective group rather than elemental chemical shifts. The two primary chemical groups identified in many of the zeolites seem to be a unit that resembles SiO/sub 2/ and another that mimics N/sup + +/-Al/sub 2/O/sub 4//sup 2 -/ (where N symbolizes the cations, usually alkali or alkaline earth species that balance the aluminate charge), a feature supported by quantum calculations, relatively narrow line widths, and reproducible valence band and loss data. These results have been employed to determine the relative purity of the surface region of different conventionally prepared zeolite systems. High-resolution ESCA studies of mordenite, ZSM-5, a silicate surfaces always seem to exhibit Al(2p) spectra that are significantly broadened into patterns that suggest several Al-containing species. The nonzeolites present at the surface of these systems generally constitute more than 50% of the total aluminum. The primary impurity species have been identified as metal aluminates and aluminas in differing ratios apparently depending upon the cation (e.g., sodium) concentrations. The possible presence of silica on the surface of some freshly prepared zeolite systems is suggested, but unconfirmed.

Barr, T.L.; Lishka, M.A.

1986-06-11

370

Growth and engineering of microporous zeolite films and coatings  

SciTech Connect

Developing very thin molecular sieve films (< 1 {micro}m), required by many zeolite film-based applications, has been found continually to be a technical challenge. The synthesis strategy of this work is to elucidate some of the parameters that influence the morphology, orientation, surface cover density and thickness of Si-ZSM-5 films on supported substrates. Three different methods to growth zeolite coatings on fused silica have been studied and compared. The zeolite films have been characterized by field emission-SEM, XRD, sorption study and transmitting spectroscopy. At the early stage of crystal growth, the gel layer spontaneously condensed on the substrate surface may have a large porosity of 15%. The strong affinity to grow the (010) faces along the substrate surface is possibly responsible for the preferred orientation of the films. The conditions for synthesis of closely packed coatings, consisting of sub-micron crystals with preferred orientation, are also identified. Engineering issues for fabrication of low optical scattering zeolitic films will also be discussed for designing molecular sieve optical devices.

Yan, Y.; Chaudhuri, S.R.; Sarkar, A. [YTC America Inc., Camarillo, CA (United States)

1996-12-31

371

Zeolitic imidazolate frameworks for kinetic separation of propane and propene  

DOEpatents

Zeolitic Imidazolate Frameworks (ZIFs) characterized by organic ligands consisting of imidazole ligands that are either essentially all 2-chloroimidazole ligands or essentially all 2-bromoimidazole ligands are disclosed. Methods for separating propane and propene with the ZIFs of the present invention, as well as other ZIFs, are also disclosed.

Li, Jing; Li, Kunhao; Olson, David H.

2014-08-05

372

Catalase-like activity studies of the manganese(II) adsorbed zeolites  

NASA Astrophysics Data System (ADS)

Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

?içek, Ekrem; Dede, Bülent

2013-12-01

373

Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors  

PubMed Central

The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors. PMID:22666081

Zheng, Yangong; Li, Xiaogan; Dutta, Prabir K.

2012-01-01

374

Zeolite in horizontal permeable reactive barriers for artificial groundwater recharge  

NASA Astrophysics Data System (ADS)

The Spanish Water Reuse Royal Decree 1620/2007 considers groundwater recharge as a feasible use of reclaimed water. To achieve the water quality established in the above-mentioned legislation, a tertiary wastewater treatment is required. In this context, the infiltration of effluents generated by secondary wastewater treatments through a Horizontal Permeable Reactive Barrier (HPRB) may represent a suitable regeneration technology. Some nutrients (phosphate and ammonium) and some Pharmaceutical and Personal Care Products (PPCPs) are not fully removed in conventional wastewater treatment plants. To avoid groundwater contamination when effluents of wastewater treatments plants are used in artificial recharge activities, these contaminants have to be removed. Due to its sorption capacities, zeolite is among the most used reactive materials in Permeable Reactive Barrier (PRB). Therefore, the main goal of this study is to evaluate the zeolite retention effectiveness of nutrients and PPCPs occurring in treated wastewater. Batch sorption experiments using synthetic wastewater (SWW) and zeolite were performed. A 1:4 zeolite/SWW ratio was selected due to the high sorption capacity of the reactive material.The assays were carried out by triplicate. All the bottles containing the SWW-zeolite mixture were placed on a mechanical shaker during 24 hours at 140 rpm and 25 °C. Ammonium and phosphate, as main nutrients, and a group of PPCPs were selected as compounds to be tested during the experiments. Nutrients were analyzed by ion chromatography. For PPCPs determination, Solid Phase Extraction (SPE) was applied before their analysis by liquid chromatography-mass spectrometry time of flight (LC-MS/ TOF). The experimental data were fitted to linearized Langmuir and Freundlich isotherm equations to obtain sorption parameters. In general, Freundlich model shows a greater capability of reproducing experimental data. To our knowledge, sorption of the investigated compounds on zeolite has rarely been addressed and this holds true especially for PPCPs. Therefore, the obtained results will be useful for the design and characterization of those HPRBs in which zeolite will be employed to regenerate treated wastewater for artificial recharge activities.

Leal, María; Martínez-Hernández, Virtudes; Lillo, Javier; Meffe, Raffaella; de Bustamante, Irene

2013-04-01

375

Clinoptilolite zeolitized tuff from Central Alborz Range, North Iran  

NASA Astrophysics Data System (ADS)

Zeolites are hydrated alumino-silicates of the alkaline and alkaline earth cations, principally sodium, potassium, calcium, and magnesium (Iijima 1980; Hay 1981). Zeolites occur principally in unmetamorphosed sedimentary rocks and are particularly widespread in volcani-clastic strata (Hay, 1978). Clinoptilolite is a natural zeolite of the heulandite group with the simplified formula of (Na, K)6 Si30 Al6 O72 .nH2. It is the most common natural zeolite found mainly in sedimentary rocks of volcanic origin. Alborz zone is one of the important geological divisions in Iran. This zone is restricted to Kopeh dagh zone in North & Central Iranian zone in South and is a region of active deformation within the broad Arabian-Eurasia collision zone (Allen et al. 2003). The zeolitized green tuff belt from Central Alborz which introduce here are made of volcanoclastic sequence of Karaj Formation. This belt is about 40 km long along Alborz Range and is Eocene in age. Zeolites and associated minerals of this altered vitric tuff studied. Zeolitization took place in some beds of Karaj Formations, with average range of 3 to 300 meters thickness. There are several gypsum lenses which interbed with a widespread green tuff succession in the studied area. On the basis of chemical composition these tuffs are in the range of acid to intermediate volcanic rocks. Also magmatic affinity is calc-alkaline and geological setting of the area belongs to volcanic arc granitoid. Petrographic data has shown that various shape and size of shard glass are the main component of tuffs. Based on the field studies, detail microscopy, XRD and electron microprobe analysis (EMPA), the following main minerals are determined: Clinoptilolite+montmorillonite+crystobalite. Clinoptilolite and smectite are predominant minerals in all altered samples. Concerning the Si/Al ratio of 40 point analyses of glass shards the Alborz tuff has clinoptilolite composition. Otherwise the chemical composition of altered shard glass is very similar to clinoptilolite structural formula. By using medium results of chemical data the structural formula for Firuzkuh clinoptilolite is as follow: Si 29.91 Al 6.01 Fe2+ 951 Mg2+ 0.393 Ca 0.222 Na 3.162 K 1.422 Paleogeographic conditions have provided a marginal shallow seawater environment which has been filled by volcanoclastics sequence. In Eocene the zeolitization occur as layers which are confined stratigraphically, it seems this process that took place only in preferred tuffaceous horizons which enriched by shard glass. So the term staratabound can be used for this type zeolitization. In altered tuffs there are a close relationship between clinoptiloite and montmorilonite in some deposits. Alborz range, there was an occasionally marine environment (existence of marine microfossils) with humid climate (remnants of plants in some points). Transformation process (glass zeolite + smectite) provides a further silica contribution to the system, which finally in supersaturation and decreasing pH favors the precipitation of silica in altered tuff. This may have occurred when ground water flow become to mix with saline water to lowering the pH.

Taghipour, Batoul

2010-05-01

376

Localization of copper and copper transporters in the human brain.  

PubMed

Disturbances in brain copper result in rare and severe neurological disorders and may play a role in the pathogenesis and progression of multiple neurodegenerative diseases. Our current understanding of mammalian brain copper transport is based on model systems outside the central nervous system and no data are available regarding copper transport systems in the human brain. To address this deficit, we quantified regional copper concentrations and examined the distribution and cellular localization of the copper transport proteins Copper transporter 1, Atox1, ATP7A, and ATP7B in multiple regions of the human brain using inductively coupled plasma-mass spectrometry, Western blot and immunohistochemistry. We identified significant relationships between copper transporter levels and brain copper concentrations, supporting a role for these proteins in copper transport in the human brain. Interestingly, the substantia nigra contained twice as much copper than that in other brain regions, suggesting an important role for copper in this brain region. Furthermore, ATP7A levels were significantly greater in the cerebellum, compared with other brain regions, supporting an important role for ATP7A in cerebellar neuronal health. This study provides novel data regarding copper regulation in the human brain, critical to understand the mechanisms by which brain copper levels can be altered, leading to neurological disease. PMID:23076575

Davies, Katherine M; Hare, Dominic J; Cottam, Veronica; Chen, Nicholas; Hilgers, Leon; Halliday, Glenda; Mercer, Julian F B; Double, Kay L

2013-01-01

377

Hydrothermal interactions of cement or mortar with zeolites or montmorillonites  

SciTech Connect

Concretes, grouts, clays and/or zeolites are candidate borehole, shaft or tunnel plugging materials for any nuclear waste repository. Interactions between these plugging materials may take place under mild hydrothermal conditions during the life of a repository. Class H cement or motar (PSU/WES mixture) was reacted with one of two montmorillonites, clinoptilolite or mordenite at 100/sup 0/ and 200/sup 0/C for different periods under a confining pressure of 30 MPa. The solid reaction products were characterized by x-ray powder diffraction and scanning electron microscopy after the hydrothermal treatments. When zeolites were in contact (not intimate mixture) with class H cement, they did not seem to alter but clinoptilolite altered to analcime, and mordenite became poorly crystalline in the presence of mortar (containing NaCl) at both 100/sup 0/ and 200/sup 0/C. When cement or mortar was intimately mixed with zeolites or montmorillonites and reacted hydrothermally, the reaction resulted in the formation of Al substituted tobermorite (11A type) in all cases (this type of reaction is expected at the interface) at both 100/sup 0/ and 200/sup 0/C. The mechanism of tobermorite formation includes the decomposition of zeolites or montmorillonites in the presence of alkaline (pH approx. = 12) cement or mortar and recrystallization to form Al substituted tobermorite. Cesium sorption measurements in 0.01N CaCl/sub 2/ on the reaction products revealed that selective Cs sorption increased in most cases, even though little or none of the original zeolites and montmorillonites remained in the products. For example, Cs sorption K/sub d/ (mL/g) increased from 80 in the untreated mortar + Ca montmorillonite mixture to 1700 in the interaction product which is Al substituted tobermorite. Thus, we discover here that Al substituted tobermorite has good selectivity for Cs.

Komarneni, S.; Roy, D.M.

1983-01-01

378

Preparation of supported zeolite films and layers: Processing of zeolite suspensions and in situ growth from homogeneous solutions  

SciTech Connect

The influence of microstructure on the properties of zeolite films and means of controlling the former (film thickness, crystal orientation) are the theme of this report. Firstly, the formation of thin silicalite films from regrowth of nanocrystalline silicalite/alumina composite films is presented. The crystallites at the intergrown top layer are oriented with their straight channels parallel to the substrate film. The membranes show H{sub 2}/N{sub 2} selectivities of about 60 at 150 C. This high selectivity is attributed to the orientation of the separating layer. Secondly, the formation of oriented multilayers of zeolite L crystallites by alternating dipping of a glass substrate in a bohemite and a plate-like zeolite L suspensions is illustrated. Finally, continuous films of zeolite NaA are prepared on various substrates (glass, porous and nonporous alumina) using in situ growth from homogeneous solutions. The films exhibit good adhesion to the substrates. The films prepared on porous alumina disks show He/N{sub 2} and O{sub 2}/N{sub 2} selectivities of 10 and 0.4 respectively at 120 C.

Lovallo, M.C.; Boudreau, L.; Tsapatsis, M. [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Chemical Engineering

1996-12-31

379

Methane emissions abatement by multi-ion-exchanged zeolite A prepared from both commercial-grade zeolite and coal fly ash  

SciTech Connect

The performance of multimetal-(Cu, Cr, Zn, Ni, and Co)-ion-exchanged zeolite A prepared from both a commercial-grade sample and one produced from coal fly ash in methane emissions abatement was evaluated in this study. The ion-exchange process was used to load the metal ions in zeolite A samples. The methane conversion efficiency by the samples was studied under various parameters including the amount of metal loading (7.3-19.4 wt%), reaction temperature (25-500{sup o}C), space velocity (8400-41 900 h{sup -1}), and methane concentration (0.5-3.2 vol %). At 500{sup o}C, the original commercial-grade zeolite A catalyzed 3% of the methane only, whereas the addition of different percentages of metals in the sample enhanced the methane conversion efficiency by 40-85%. Greater methane conversion was observed by increasing the percentage of metals added to the zeolite even though the BET surface area of the zeolite consequently decreased. Higher percentage methane conversion over the multi-ion-exchanged samples was observed at lower space velocities indicating the importance of the mass diffusion of reactants and products in the zeolite. Compared to the multi-ion-exchanged zeolite A prepared from the commercial-grade zeolite, the one produced from coal fly ash demonstrated similar performances in methane emissions abatement, showing the potential use of this low cost recycled material in gaseous pollutant treatment. 25 refs., 3 figs., 2 tabs.

K.S. Hui; C.Y.H. Chao [Hong Kong University of Science and Technology, Kowloon (China). Department of Mechanical Engineering

2008-10-01

380

Synchrotron X-ray and Optical Studies of the Structure of HgSe Semiconductor Nanoclusters Confined in Zeolite L and Zeolite Y  

SciTech Connect

HgSe semiconductor nanoclusters were fabricated in nearly spherical pores of zeolite Y and one-dimensional (1D) tubular pores of zeolite L. Anomalous x-ray scattering (AXS) data sets were collected on both HgSe/zeolite Y and HgSe/zeolite L systems, together with optical studies (Raman and UV-visible absorption). Two distinct structural models were determined by performing the Rietveld refinement on AXS data sets. Given the existence of a pronounced diffuse scattering in both filled zeolites and our refined models without the observed diffuse background, for each system, we propose the existence of an average HgSe nanocluster or a 1D nanostructure and the related disorder within the nanocluster which gives off the diffuse scattering. Optical studies were used to complement our x-ray structural work.

Abeykoon,A.; Castro-Colin, M.; Anokhina, E.; Iliev, M.; Donner, W.; Jacobson, A.; Moss, S.

2008-01-01

381

Copper Proteins and Oxygen  

PubMed Central

A comprehensive survey of the interaction of the copper proteins and oxygen is presented including a correlation of structure, function, and other properties of the known copper oxidases and of hemocyanin. The origin of their blue color and the structure of copper complexes and copper proteins are related to the oxidation state of copper ion and relevant electronic transitions probably arising from the formation of charge transfer complexes. The oxygen reactions of hemocyanin, ceruloplasmin, and cytochrome oxidase show half-saturation values far below the other Cu enzymes. The formation of hydrogen peroxide as a reaction product is associated with the presence of one Cu atom per oxidase molecule or catalytic system. Water is the corresponding product of the other Cu oxidases with four or more Cu atoms per molecule, except for monoamine oxidase. Mechanisms for the oxidase action of the two and four electron transfer Cu oxidases and tyrosinase are proposed. These reactions account for the number, the oxidation-reduction potential, and the oxidation state of Cu in the resting enzyme, the cyclical change from Cu(II) to Cu(I), the diatomic nature of O2, the sequence of the oxidation and reduction reactions, and other salient features. The catalytic reactions involved in the oxidation of ascorbic acid by plant ascorbate oxidase, ceruloplasmin, and Cu(II) are compared. Finally the substrate specificity, inhibitory control, and the detailed mechanism of the oxidase activity of ceruloplasmin are summarized. PMID:4285728

Frieden, Earl; Osaki, Shigemasa; Kobayashi, Hiroshi

1965-01-01

382

Permit application modifications  

SciTech Connect

This document contains the Permit Application Modifications for the Y-12 Industrial Landfill V site on the Oak Ridge Reservation. These modifications include the assessment of stability of the proposed Landfill V under static and loading conditions. Analyses performed include the general slope stability, veneer stability of the bottom liner and cover system, and a liquefaction potential assessment of the foundation soils.

NONE

1995-11-01

383

Histone onco-modifications  

Microsoft Academic Search

Post-translational modification of histones provides an important regulatory platform for processes such as gene expression, DNA replication and repair, chromosome condensation and segregation and apoptosis. Disruption of these processes has been linked to the multistep process of carcinogenesis. We review the aberrant covalent histone modifications observed in cancer, and discuss how these epigenetic changes, caused by alterations in histone-modifying enzymes,

J Füllgrabe; E Kavanagh; B Joseph

2011-01-01

384

?-? interaction of aromatic groups in amphiphilic molecules directing for single-crystalline mesostructured zeolite nanosheets  

NASA Astrophysics Data System (ADS)

One of the challenges in material science has been to prepare macro- or mesoporous zeolite. Although examples of their synthesis exist, there is a need for a facile yet versatile approach to such hierarchical structures. Here we report a concept for designing a single quaternary ammonium head amphiphilic template with strong ordered self-assembling ability through ?-? stacking in hydrophobic side, which stabilizes the mesostructure to form single-crystalline mesostructured zeolite nanosheets. The concept is demonstrated for the formation of a new type of MFI (zeolite framework code by International Zeolite Association) nanosheets joined with a 90° rotational boundary, which results in a mesoporous zeolite with highly specific surface area even after calcination. Low binding energies for this self-assembling system are supported by a theoretical analysis. A geometrical matching between the arrangement of aromatic groups and the zeolitic framework is speculated for the formation of single-crystalline MFI nanosheets.

Xu, Dongdong; Ma, Yanhang; Jing, Zhifeng; Han, Lu; Singh, Bhupendra; Feng, Ji; Shen, Xuefeng; Cao, Fenglei; Oleynikov, Peter; Sun, Huai; Terasaki, Osamu; Che, Shunai

2014-06-01

385

?-? interaction of aromatic groups in amphiphilic molecules directing for single-crystalline mesostructured zeolite nanosheets.  

PubMed

One of the challenges in material science has been to prepare macro- or mesoporous zeolite. Although examples of their synthesis exist, there is a need for a facile yet versatile approach to such hierarchical structures. Here we report a concept for designing a single quaternary ammonium head amphiphilic template with strong ordered self-assembling ability through ?-? stacking in hydrophobic side, which stabilizes the mesostructure to form single-crystalline mesostructured zeolite nanosheets. The concept is demonstrated for the formation of a new type of MFI (zeolite framework code by International Zeolite Association) nanosheets joined with a 90° rotational boundary, which results in a mesoporous zeolite with highly specific surface area even after calcination. Low binding energies for this self-assembling system are supported by a theoretical analysis. A geometrical matching between the arrangement of aromatic groups and the zeolitic framework is speculated for the formation of single-crystalline MFI nanosheets. PMID:24957696

Xu, Dongdong; Ma, Yanhang; Jing, Zhifeng; Han, Lu; Singh, Bhupendra; Feng, Ji; Shen, Xuefeng; Cao, Fenglei; Oleynikov, Peter; Sun, Huai; Terasaki, Osamu; Che, Shunai

2014-01-01

386

XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag  

NASA Astrophysics Data System (ADS)

The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst.

Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi

2007-02-01

387

Preparation of zeolite A and faujasite membranes from a clear solution  

SciTech Connect

Zeolite A and faujasite- (FAU-)type zeolite membranes were prepared under identical conditions from solutions of the same composition, with the only difference being the seed crystal used. The zeolite A membrane was formed on a substrate seeded with zeolite A crystals, while the FAU membrane was formed with zeolite Y seeds. The induction period of clear solution was used to prevent the influence of precipitated crystals that will eventually form in the clear solution and to keep the composition of the synthesis solution constant. Zeolite crystals increased in size with synthesis time and formed a continuous membrane on a porous substrate. Selectivity in a liquid mixture separation by pervaporation increased as crystals grew, indicating a decrease in intercrystalline region size.

Kumakiri, Izumi; Yamaguchi, Takeo; Nakao, Shinichi

1999-12-01

388

Preparation of high purity copper fluoride by fluorinating copper hydroxyfluoride  

NASA Technical Reports Server (NTRS)

Copper fluoride containing no more than 50 ppm of any contaminating element was prepared by the fluorination of copper hydroxyfluoride. The impurity content was obtained by spark source mass spectrometry. High purity copper fluoride is needed as a cathode material for high energy density batteries.

King, R. B.; Lundquist, J. R.

1969-01-01

389

Possible involvement of copper(II) in Alzheimer disease.  

PubMed

The beta-amyloid (Abeta) peptide is a principal component of insoluble amyloid plaques that are characteristic neuropathological features of Alzheimer disease (AD). The amyloid peptide also exists as a normal soluble protein that undergoes a pathogenic transition to an aggregated, fibrous form. This transition can be affected by extraneous proteinaceous elements and nonproteinaceous elements such as copper ions, which may promote aggregation and/or stabilization of the fibrils. Copper has been found in abnormally high concentrations in amyloid plaques and AD-affected neuropil, and copper-selective chelators have been shown to dissolve Abeta peptide from postmortem brain specimens. Although Cu(2+) is an essential element for life and the function of numerous enzymes is basic to neurobiology, free or incorrectly bound Cu(2+) can also catalyze generation of the most damaging radicals, such as hydroxyl radical, giving a chemical modification of the protein, alternations in protein structure and solubility, and oxidative damage to surrounding tissue. PMID:12426149

Kowalik-Jankowska, Teresa; Ruta-Dolejsz, Monika; Wisniewska, Kornelia; Lankiewicz, Leszek; Kozlowski, Henryk

2002-10-01

390

Possible involvement of copper(II) in Alzheimer disease.  

PubMed Central

The beta-amyloid (Abeta) peptide is a principal component of insoluble amyloid plaques that are characteristic neuropathological features of Alzheimer disease (AD). The amyloid peptide also exists as a normal soluble protein that undergoes a pathogenic transition to an aggregated, fibrous form. This transition can be affected by extraneous proteinaceous elements and nonproteinaceous elements such as copper ions, which may promote aggregation and/or stabilization of the fibrils. Copper has been found in abnormally high concentrations in amyloid plaques and AD-affected neuropil, and copper-selective chelators have been shown to dissolve Abeta peptide from postmortem brain specimens. Although Cu(2+) is an essential element for life and the function of numerous enzymes is basic to neurobiology, free or incorrectly bound Cu(2+) can also catalyze generation of the most damaging radicals, such as hydroxyl radical, giving a chemical modification of the protein, alternations in protein structure and solubility, and oxidative damage to surrounding tissue. PMID:12426149

Kowalik-Jankowska, Teresa; Ruta-Dolejsz, Monika; Wisniewska, Kornelia; Lankiewicz, Leszek; Kozlowski, Henryk

2002-01-01

391

Electrocatalytic characteristics of uric acid oxidation at graphite–zeolite-modified electrode doped with iron (III)  

Microsoft Academic Search

A new method is developed for the catalytic oxidation of uric acid at graphite–zeolite-modified electrode doped with iron (III) (Fe3+Y\\/ZCME). Iron (III) exchanged in zeolite Y act as catalyst to oxidize uric acid. First, the electrochemical behavior of iron (III) incorporated in the zeolite Y-modified electrode was studied. The results illustrate that diffusion controls the ferric\\/ferrous redox process at the

M. Mazloum Ardakani; Z. Akrami; H. Kazemian; H. R. Zare

2006-01-01

392

Effective solidification/stabilisation of mercury-contaminated wastes using zeolites and chemically bonded phosphate ceramics.  

PubMed

In this study, two kinds of zeolites materials (natural zeolite and thiol-functionalised zeolite) were added to the chemically bonded phosphate ceramic processes to treat mercury-contaminated wastes. Strong promotion effects of zeolites (natural zeolite and thiol-functionalised zeolite) on the stability of mercury in the wastes were obtained and these technologies showed promising advantages toward the traditional Portland cement process, i.e. using Portland cement as a solidification agent and natural or thiol-functionalised zeolite as a stabilisation agent. Not only is a high stabilisation efficiency (lowered the Toxicity Characteristic Leaching Procedure Hg by above 10%) obtained, but also a lower dosage of solidification (for thiol-functionalised zeolite as stabilisation agent, 0.5?g?g(-1) and 0.7?g?g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) and stabilisation agents (for natural zeolite as stabilisation agent, 0.35?g?g(-1) and 0.4?g?g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) were used compared with the Portland cement process. Treated by thiol-functionalised zeolite and chemically bonded phosphate ceramic under optimum parameters, the waste containing 1500?mg?Hg?kg(-1) passed the Toxicity Characteristic Leaching Procedure test. Moreover, stabilisation/solidification technology using natural zeolite and chemically bonded phosphate ceramic also passed the Toxicity Characteristic Leaching Procedure test (the mercury waste containing 625?mg?Hg?kg(-1)). Moreover, the presence of chloride and phosphate did not have a negative effect on the chemically bonded phosphate ceramic/thiol-functionalised zeolite treatment process; thus, showing potential for future application in treatment of 'difficult-to-manage' mercury-contaminated wastes or landfill disposal with high phosphate and chloride content. PMID:25568090

Zhang, Shaoqing; Zhang, Xinyan; Xiong, Ya; Wang, Guoping; Zheng, Na

2015-02-01

393

Qualification testing and full-scale demonstration of titanium-treated zeolite for sludge wash processing  

Microsoft Academic Search

Titanium-treated zeolite is a new ion-exchange material that is a variation of UOP (formerly Union Carbide) IONSIV IE-96 zeolite (IE-96) that has been treated with an aqueous titanium solution in a proprietary process. IE-96 zeolite, without the titanium treatment, has been used since 1988 in the West Valley Demonstration Project`s (WVDP) Supernatant Treatment System (STS) ion-exchange columns to remove Cs-137

Dalton

1997-01-01

394

Characterisation and environmental application of an Australian natural zeolite for basic dye removal from aqueous solution  

Microsoft Academic Search

An Australian natural zeolite was collected, characterised and employed for basic dye adsorption in aqueous solution. The natural zeolite is mainly composed of clinoptiloite, quartz and mordenite and has cation-exchange capacity of 120meq\\/100g. The natural zeolite presents higher adsorption capacity for methylene blue than rhodamine B with the maximal adsorption capacity of 2.8×10?5 and 7.9×10?5mol\\/g at 50°C for rhodamine B

Shaobin Wang; Z. H. Zhu

2006-01-01

395

Ruthenium supported on zeolite A: preparation and characterisation of a stable catalyst for ammonia synthesis  

Microsoft Academic Search

Reaction of Ru(NH3)6Cl3 with Na-A and K-A zeolites yielded oligomeric amino-oxo-complexes supported on the zeolite. Controlled thermal activation under hydrogen converted the precursor in a two-step reaction into an active catalyst with good long-term stability and resistance against small doses of oxygen poison. Several nanometers sized Ru metal particles are chemically bonded to the zeolite surface which provides in the

J. Wellenbüscher; M. Muhler; W. Mahdi; U. Sauerlandt; J. Schütze; G. Ertl; R. Schlögl

1994-01-01

396

Preparation and characterization of thin zeolite MFI membranes on porous supports  

Microsoft Academic Search

Thin (2–7?m) polycrystalline randomly-oriented zeolite MFI membranes were prepared on an ?-Al2O3 support by one or more subsequent hydrothermal treatments. Different particle sizes (275–700nm) in the layer were achieved by changing the synthesis temperature (371–459K). Zeolite membranes, prepared by two subsequent hydrothermal treatments have an optimum quality. Membranes prepared by a single hydrothermal treatment have defects and zeolite membranes obtained

Z. A. E. P. Vroon; K. Keizer; A. J. Burggraaf; H. Verweij

1998-01-01

397

Environmental Applications of Natural Zeolitic Materials Based on Their Ion Exchange Properties  

Microsoft Academic Search

\\u000a Present and potential use of natural zeolites as cation exchangers in environmental protection is reviewed. Siliceous zeolites,\\u000a such as chabazite, clinoptilolite, mordenite and phillipsite, exhibit good selectivities for cations with low charge density,\\u000a e.g., Cs+ and NH4\\u000a +, and for cations with low hydration energy, such as Pb2+. Zeolitised tuffs, containing the mentioned zeolites, may therefore be utilised for removing

C. Colella; Piazza Ie; V. Tecchio

398

Location of platinum clusters in PtCaY and PtNaY zeolites  

E-print Network

) spectra of PtNaY after reduction in flowing hydrogen in increments of 100 C/hr to 350'C 61 63 65 INTRODUCTION In heterogeneous catalysis, frequently used supports for active group VIII metals are zeolites, which are crystalline aluminosilicates. A... metal-loaded catalyst may be prepared by exchanging cations into the zeolite structure. Catalytic activity is obtained by the reduction of the cation to metal. In order to understand the properties of metal-exchanged zeolites it is important...

Treybig, Duane Steven

1980-01-01

399

Alkaline Hydrothermal Conversion of Fly Ash Filtrates Into Zeolites 2: Utilization in Wastewater Treatment  

Microsoft Academic Search

Filtrates were collected using a codisposal reaction wherein fly ash was reacted with acid mine drainage. These codisposal filtrates were then analyzed by X-ray Fluores- cence spectrometry for quantitative determination of the SiO2 and Al2O3 content. Al- kaline hydrothermal zeolite synthesis was then applied to the filtrates to convert the fly ash material into zeolites. The zeolites formed under the

Vernon Somerset; Leslie Petrik; Emmanuel Iwuoha

2005-01-01

400

High capacity cation exchanger by hydrothermal zeolitization of coal fly ash  

Microsoft Academic Search

During; hydrothermal treatment in NaOH medium coal fly ash partially transformed to zeolite P and\\/or hydroxysodalite, while quartz slowly dissolved and mullite remained stable. Residual coal favored the formation of zeolite P. The relative proportion of the two zeolites could be changed by seeding. During fusion of fly ash with NaOH an endothermic reaction at 170–180°C occurred, resulting in formation

V. Berkgaut; A. Singer

1996-01-01

401

Conversion of methanol and other O-compounds to hydrocarbons over zeolite catalysts  

Microsoft Academic Search

Experimental data show that Mobil Research and Development Corp.'s new gasoline synthesis from methanol on zeolites of pore dimensions intermediate between faujasites and zeolite A (described in patent literature) gives similar product distributions from methanol, tert.-butanol and 1-heptanol. The shape-selective zeolite produces essentially no hydrocarbons above Cââ, mainly isoparaffins, isoolefins, and methylsubstituted benzenes. Xylenes are produced in equilibrium amounts, but

C. D. Chang; A. J. Silvestri

1977-01-01

402

Preparation of highly selective zeolite ZSM-5 membranes by a post-synthetic coking treatment  

Microsoft Academic Search

Zeolite ZSM-5 membranes with high n-butane:isobutane selectivities, e.g., 322 at 185°C, are obtained by a selective deposition of coke into non-zeolitic pores. The zeolite membranes are prepared by in situ crystallization on either bare porous ?-Al2O3 support disks or disks that are pretreated to include a diffusion barrier. The post-synthetic coking treatment is accomplished by impregnating these membranes with liquid

Yushan Yan; Mark E. Davis; George R. Gavalas

1997-01-01

403

EPR and Catalytic Investigation of Cu(Salen) Complexes Encapsulated in Zeolites  

Microsoft Academic Search

Zeolite-Y-encapsulated Cu(salen) and Cu(5-Cl-salen) complexes, where salen is N,N?-ethylenebis(salicylidenaminato), have been synthesized and characterized by various physicochemical techniques. “Neat” complexes showed broad EPR spectra corresponding to nearest neighbor spin–spin interactions whereas the zeolite-encapsulated metal complexes showed well-resolved metal hyperfine features similar to spectra in dilute frozen solutions indicating the encapsulation of monomeric salen complexes in zeolite cavities. Molecules adsorbed on

S. Deshpande; D. Srinivas; P. Ratnasamy

1999-01-01

404

The hydrophobic effect as a driving force for solute uptake by dealuminated zeolite Y  

Microsoft Academic Search

The hydrophobic nature of a commercial sample of dealuminated zeolite Y (DAY), heretofore referred to as Y901 and available as CBV901 from Zeolyst International, has been examined. Studies were focused on Y901 and related zeolites that were interfaced with bathing polar solvents. Binding isotherms for uptake of non-polar arene test solutes by various zeolites were evaluated from measurements of solute

Eric H. Ellison; Deshi Moodley

2007-01-01

405

Agricultural soils spiked with copper mine wastes and copper concentrate: implications for copper bioavailability and bioaccumulation.  

PubMed

A better understanding of exposure to and effects of copper-rich pollutants in soils is required for accurate environmental risk assessment of copper. A greenhouse experiment was conducted to study copper bioavailability and bioaccumulation in agricultural soils spiked with different types of copper-rich mine solid wastes (copper ore, tailing sand, smelter dust, and smelter slag) and copper concentrate. A copper salt (copper sulfate, CuSO4) that frequently is used to assess soil copper bioavailability and phytotoxicity also was included for comparison. Results showed that smelter dust, tailing sand, and CuSO4 are more likely to be bioavailable and, thus, toxic to plants compared with smelter slag, concentrate, and ore at equivalent total copper concentrations. Differences may be explained by intrinsic differences in copper solubilization from the source materials, but also by their capability to decrease soil pH (confounding effect). The copper toxicity and bioaccumulation in plants also varied according to soil physicochemical characteristics (e.g., pH and total organic carbon) and the available levels of plant nutrients, such as nitrogen, phosphorus, and potassium. Chemistry/mineralogy of mine materials, soil/pore-water chemistry, and plant physiological status thus should be integrated for building adequate models to predict phytotoxicity and environmental risk of copper. PMID:16566155

Ginocchio, Rosanna; Sánchez, Pablo; de la Fuente, Luz María; Camus, Isabel; Bustamante, Elena; Silva, Yasna; Urrestarazu, Paola; Torres, Juan C; Rodríguez, Patricio H

2006-03-01

406

The mineralogy of copper electrorefining  

NASA Astrophysics Data System (ADS)

The impurities in copper anodes occur both in solid solution in the copper metal matrix and in discrete inclusions at the copper grain boundaries. During electrorefining, all the impurities undergo extensive chemical and/or morphological changes. These changes impact significantly on anode passivation, cathode quality, electrolyte purification and, of course, the subsequent recovery of by-products from the anode slimes. Recently, mineralogical studies have been undertaken to characterize the various impurities and elucidate their transformations during copper electrorefining.

Chen, T. T.; Dutrizac, J. E.

1990-08-01

407

Synthesis and characterization of various zeolites and study of dynamic adsorption of dimethyl methyl phosphate over them  

SciTech Connect

Graphical abstract: Thermal desorption pattern of DMMP over various zeolites (a) 1st desorption and (b) 2nd desorption. - Highlights: • Synthesis of Zeolite-A, MCM-22, Zeolite-X and Erionite by hydrothermal method. • Zeolites were characterized by using XRD, FTIR, BET, NH{sub 3}-TPD, SEM and EDS techniques. • Dynamic adsorption of DMMP on zeolites was carried out using TPD plus chemisorption system. • Thermal desorption of DMMP on zeolites was carried using the same system. - Abstract: Zeolite-A, MCM-22, Zeolite-X and Erionite were synthesized successfully under hydrothermal conditions and were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET) surface area analysis and thermal programmed desorption (TPD). Dynamic adsorption of dimethyl methyl phosphate (DMMP) was carried out on these zeolites. Zeolite-X having high surface area among all four zeolites shows highest adsorption capacity followed by Erionite and MCM-22 where as Zeolite-A shows the least. For all zeolites adsorption was found to be high initially and it then decreases with increase in injected volume. Then desorption pattern was analyzed which shows two types of peaks, sharp peak representing desorption of physisorbed DMMP and a broad peak representing desorption of strongly chemisorbed DMMP.

Khanday, Waheed Ahmad, E-mail: khanday.waheed@yahoo.com [S.O.S in Chemistry, Jiwaji University, Gwalior, M.P. 474011 (India); Majid, Sheikh Abdul [S.O.S in Chemistry, Jiwaji University, Gwalior, M.P. 474011 (India); Chandra Shekar, S. [Defence R and D Establishment, Jhansi Road, Gwalior, M.P. 474002 (India); Tomar, Radha [S.O.S in Chemistry, Jiwaji University, Gwalior, M.P. 474011 (India)

2013-11-15

408

Synthesis and characterization of zeolites prepared from industrial fly ash.  

PubMed

In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm(3) of 3 mol?·?dm(-3) NaOH, 75 °C), Na-P1 (20 g fly ash, 0.5 dm(3) of 3 mol?·?dm(-3) NaOH, 95 °C), and sodalite (20 g fly ash, 0.8 dm(3) of 5 mol?·?dm(-3) NaOH?+?0.4 dm(3) of 3 mol?·?dm(-3) NaCl, 95 °C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N2 isotherm adsorption/desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m(2)?·?g(-1), while for the Na-P1 and sodalite it was 71 and 33 m(2)?·?g(-1), respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq?·?g(-1), Na-P1 at 0.72 meq?·?g(-1), and sodalite at 0.56 meq?·?g(-1). The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination. PMID:24838802

Franus, Wojciech; Wdowin, Magdalena; Franus, Ma?gorzata

2014-09-01

409

Electrical Conductivity Response toward Ketone Vapors of Poly(Para-Phenylene Vinylene)/Zeolite Y Composites  

NASA Astrophysics Data System (ADS)

Investigation of the effect of 3 different types of cation types in Zeolite Y; Zeolite Y(Si/Al=5.1, Na+), Zeolite Y(Si/Al=5.1, NH3+), Zeolite Y(Si/Al=5.1, H+) on the electrical conductivity sensitivity when exposed to the 3 different types of ketone vapors (Acetone, Methyl Ethyl Ketone(MEK) and Methyl Iso Buthyl Ketone(MIBK)), which are flammable and toxic components in order to improve the selectivity and sensitivity of dPPV/Zeolite Y and the interactions between the ketone molecules and the composites with respect to the electrical conductivity sensitivity are investigated though the infrared spectroscopy(FTTIR). All composites show definite positive responses towards the ketone vapors (Acetone, Methyl Ethyl Ketone (MEK), Methyl Iso-Buthyl Ketone (MIBK)). The electrical conductivity sensitivities of the composites increase linearly with increasing surface area of the Zeolite Y. The highest electrical conductivity sensitivity is obtained with the dPPV_/Zeolite Y (Si/Al = 5.1, NH4+), higher than those of dPPV_/Zeolite Y (Si/Al = 5.1, Na+) and dPPV_/Zeolite Y (Si/Al = 5.1, H+) when exposed to acetone. Amongst the Ketone vapors, acetone induces the highest electrical conductivity sensitivity, whereas MIBK induces the lowest electrical conductivity sensitivity.

Kamonsawas, Jirarat; Sirivat, Anuvat

2012-02-01

410

Hydrothermal Synthesis and Characterization of Aluminum-Free Mn-? Zeolite: A Catalyst for Phenol Hydroxylation.  

PubMed

Zeolite beta, especially heteroatomic zeolite beta, has been widely used in the industries of fine chemicals and petroleum refining because of its outstanding thermal stability, acid resistance, and unique 3-D open-frame structure. In this paper, aluminum-free Mn-? zeolite was hydrothermally synthesized in the SiO2-MnO2-(TEA)2O-NaF-H2O system. The effect of the chemical composition of the precursor mixture to the crystallization of the Al-free Mn-? zeolite was investigated. The synthesized Al-free Mn-? zeolite was characterized by inductively coupled plasma (ICP), XRD, thermogravimetric/differential thermal analysis (TG/DTA), N2 adsorption-desorption, FT-IR, UV-vis, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The results show that the synthesized zeolite has a structure of ? zeolite with good crystallinity and Mn ions present in the framework of the zeolite. The synthesized Al-free Mn-? zeolite shows great catalytic activity toward the phenol hydroxylation reaction using H2O2 as the oxidant. Approximately 35% of phenol conversion and ?98% of dihydroxybenzene selectivity can be obtained under the optimal conditions. PMID:25556927

He, Zhen; Wu, Juan; Gao, Bingying; He, Hongyun

2015-02-01

411

Preparation of CPB-modified FAU zeolite for the removal of tannery wastewater contaminants .  

E-print Network

??The preparation of organomodified zeolites with different framework structures (FAU, LTA and MOR) using N-cetylpyridinium bromide (CPB) as tailoring agent was studied. The sorption properties… (more)

Covarrubias, Cristián

2008-01-01

412

Influence of zeolites in PDMS membranes. Pervaporation of water/alcohol mixtures  

SciTech Connect

A strong influence of the zeolite was found on the pervaporation of alcohol/water mixtures using filled PDMS membranes. In all cases, the zeolites reduced the swelling of the PDMS. Incorporation of the hydrophilic zeolite Y increased water fluxes, while ZSM-5 reduced both water and alcohol fluxes due to a partial retention of these molecules in the zeolite. For branched alcohols, the extreme importance of diffusion led to a strong dependency of selectivity and flux on temperature. Compared with commercially available PDMS membranes, better results were realized with the self-prepared membranes. 19 refs., 7 figs., 1 tab.

Vankelecom, I.F.J.; Depre, D.; De Beukelaer, S.; Uytterhoeven, J.B. [Centrum voor Oppervlaktechemie en Katalyse, Leuven (Belgium)

1995-08-31

413

Ammonium removal from groundwater using a zeolite permeable reactive barrier: a pilot-scale demonstration.  

PubMed

In situ remediation of ammonium-contaminated groundwater is possible through a zeolite permeable reactive barrier (PRB); however, zeolite's finite sorption capacity limits the long-term field application of PRBs. In this paper, a pilot-scale PRB was designed to achieve sustainable use of zeolite in removing ammonium (NH(4)(+)-N) through sequential nitrification, adsorption, and denitrification. An oxygen-releasing compound was added to ensure aerobic conditions in the upper layers of the PRB where NH(4)(+)-N was microbially oxidized to nitrate. Any remaining NH(4)(+)-N was removed abiotically in the zeolite layer. Under lower redox conditions, nitrate formed during nitrification was removed by denitrifying bacteria colonizing the zeolite. During the long-term operation (328 days), more than 90% of NH(4)(+)-N was consistently removed, and approximately 40% of the influent NH(4)(+)-N was oxidized to nitrate. As much as 60% of the nitrate formed in the PRB was reduced in the zeolite layer after 300 days of operation. Removal of NH(4)(+)-N from groundwater using a zeolite PRB through bacterial nitrification and abiotic adsorption is a promising approach. The zeolite PRB has the advantage of achieving sustainable use of zeolite and immediate NH(4)(+)-N removal. PMID:25401319

Li, Shengpin; Huang, Guoxin; Kong, Xiangke; Yang, Yingzhao; Liu, Fei; Hou, Guohua; Chen, Honghan

2014-01-01

414

Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity  

PubMed Central

Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12–3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO3. The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller–Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications. PMID:21383858

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

2011-01-01

415

High adherence copper plating process  

SciTech Connect

A process is described for applying copper to a substrate of aluminum or steel by electrodeposition and for preparing an aluminum or steel substrate for electrodeposition of copper. Practice of the invention provides good adhesion of the copper layer to the substrate.

Mignardot, H.

1992-12-31

416

Tensile behavior of nanocrystalline copper  

Microsoft Academic Search

High density nanocrystalline copper produced by inert gas condensation was tested in tension. Displacements were measured using foil strain gauges, which greatly improved the accuracy of the strain data. The Young`s modulus of nanocrystalline copper was found to be consistent with that of coarse-grained copper. Total elongations of â 1% were observed in samples with grain sizes less than 50

P. G. Sanders; J. R. Weertman; J. A. Eastman

1995-01-01

417

SOURCES OF COPPER AIR EMISSIONS  

EPA Science Inventory

The report gives results of a study to update estimates of atmospheric emissions of copper and copper compounds in the U.S. Source categories evaluated included: metallic minerals, primary copper smelters, iron and steel making, combustion, municipal incineration, secondary coppe...

418

December 200 Copper Acquisition by  

E-print Network

December 200 Copper Acquisition by Methanotrophic Bacteria 7 Term Paper HS2007 Major. One is soluble in the cytoplasm and the other is bound to the membrane. Since the expression of copper containing pMMO depends on copper availability it is supposed that some methanotrophs have developed

Fischlin, Andreas

419

Type-zero copper proteins  

Microsoft Academic Search

Many proteins contain copper in a range of coordination environments, where it has various biological roles, such as transferring electrons or activating dioxygen. These copper sites can be classified by their function or spectroscopic properties. Those with a single copper atom are either type 1, with an intense absorption band near 600 nm, or type 2, with weak absorption in

Kyle M. Lancaster; Serena DeBeer George; Keiko Yokoyama; John H. Richards; Harry B. Gray

2009-01-01

420

High-temperature decomposition of solid solutions of beta-tantalum with copper in films  

NASA Astrophysics Data System (ADS)

Using high-temperature X-ray diffractometry and electron microprobe analysis decomposition of alloys of beta-tantalum with copper produced by codeposition of sputtered ultradisperse particles of tantalum and copper has been established. At a temperature of 900°C, the precipitation of copper from the solid solution into an individual phase starts, and its diffusion onto the film surface with the formation of globular particles and simultaneous transition of the matrix ?-modification into ?-tantalum. The suggested mechanism of decomposition of solid solutions includes the following stages: the precipitation of copper into an individual phase, its diffusion onto the surface because of lattice pressure and the concentration gradient inside and outside the tantalum matrix, the coalescence of nanosized formations into drops at the coating surface, and the subsequent evaporation of copper from them in a vacuum.

Tuleushev, Yu. Zh.; Volodin, V. N.; Zhakanbaev, E. A.

2014-05-01

421

Inelastic X-ray Scattering Studies of Zeolite Collapse  

NASA Astrophysics Data System (ADS)

In situ inelastic x-ray scattering (IXS) experiments have been used to probe heterogeneity and deformability in zeolte Y as this thermally collapses to a high density amorphous (HDA) aluminosilicate phase. The Landau-Placzek ratio RLP falls slowly as amorphisation advances, increasing in the later stages of collapse clearly showing how homogeneity improves non-linearly—behaviour linked closely with the decline in molar volume VMolar. The Brillouin frequency ?Q also decreases with amorphisation in a similar fashion, signifying a non-uniform decrease in the speed of sound vl. All of these changes with zeolite amorphisation infer formation of an intermediate low density amorphous (LDA) phase. This low entropy or "perfect glass" has mechanical properties which are closer to the zeolite rather to the HDA glass—notably a very small value of Poisson's Ratio signifying unusually low resistance to deformation.

Greaves, G. Neville; Kargl, Florian; Ward, David; Holliman, Peter; Meneau, Florian

2009-01-01

422

Inelastic X-ray Scattering Studies of Zeolite Collapse  

SciTech Connect

In situ inelastic x-ray scattering (IXS) experiments have been used to probe heterogeneity and deformability in zeolte Y as this thermally collapses to a high density amorphous (HDA) aluminosilicate phase. The Landau-Placzek ratio R{sub LP} falls slowly as amorphisation advances, increasing in the later stages of collapse clearly showing how homogeneity improves non-linearly--behaviour linked closely with the decline in molar volume V{sub Molar}. The Brillouin frequency {omega}{sub Q} also decreases with amorphisation in a similar fashion, signifying a non-uniform decrease in the speed of sound v{sub l}. All of these changes with zeolite amorphisation infer formation of an intermediate low density amorphous (LDA) phase. This low entropy or 'perfect glass' has mechanical properties which are closer to the zeolite rather to the HDA glass--notably a very small value of Poisson's Ratio signifying unusually low resistance to deformation.

Greaves, G. Neville; Kargl, Florian; Ward, David [Centre for Advanced Functional Materials and Devices, Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom); Holliman, Peter [Centre for Advanced Functional Materials and Devices, College of Physical and Applied Sciences, Bangor University, Bangor LL57 2UW (United Kingdom); Meneau, Florian [Centre for Advanced Functional Materials and Devices, SOLEIL, Orme des Merisiers, Batiment A, Saint Aubin, BP 48, 91192, Gif sur Yvette Cedex (France)

2009-01-29

423

Zeolite-filled PDMS membranes. 2. Pervaporation of halogenated hydrocarbons  

SciTech Connect

In order to study in more detail the influence of the filler on pervaporation performance, silicalite, ZSM-5, and zeolite Y were incorporated in poly(dimethylsiloxane) (PDMS) and tested in pervaporation experiments with binary mixtures of chlorinated hydrocarbons (CI-HC`s) in water. The results were compared with unfilled PDMS as a reference. The highest selectivities were obtained with the silicalite-filled membranes. However, these membranes shown a decrease in permeability for voluminous components due to molecular sieving effects. In this respect, the results with zeolite Y were rather disappointing, as its larger pore size was counteracted by its high polarity, whereas ZSM-5-filled membranes showed intermediate selectivities. Therefore, mesoporous silicas were synthesized, silylated to assure their apolarity, and incorporated in PDMS. The resulting membranes showed both improved organic fluxes and selectivities in comparison with all other membranes, even for voluminous organics, proving the absence of molecular sieving effects. 8 refs., 7 figs.

Dotremount, C.; Vankelecom, I.F.J.; Morobe, M.; Uytterhoeven, J.B.; Vandecasteele, C. [Katholieke Universiteit Leuven (Belgium)] [Katholieke Universiteit Leuven (Belgium)

1997-03-20

424

Application of zeolites for radium removal from mine water.  

PubMed

For removal of radium from saline waters in Upper Silesian mines, several methods of purification have been developed. The most efficient one is based on application of barium chloride, which was implemented in full technical scale in two Polish coal mines several years ago. Very good results of purification have been achieved-the removal efficiency exceeding 95% of the initial activity. Another possibility for the removal of different ions from salty waters and brines is the application of zeolites. We found that technique as a very promising method for removal of not only radium isotopes from mine waters but also other ions (barium, iron, manganese). Treatment of several various water samples has been done to assess the removal efficiency for natural radionuclides. Preliminary results show very good effects for radium isotopes as well as for barium ions. In the paper, a short description of laboratory results of the purification of mine waters with application of synthetic zeolites is presented. PMID:23881589

Cha?upnik, Stanis?aw; Franus, Wojciech; Wysocka, Ma?gorzata; Gzyl, Grzegorz

2013-11-01

425

Precursors for formation of copper selenide, indium selenide, copper indium diselenide, and/or copper indium gallium diselenide films  

DOEpatents

Liquid-based precursors for formation of Copper Selenide, Indium Selenide, Copper Indium Diselenide, and/or copper Indium Galium Diselenide include copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent. These liquid-based precursors can be deposited in liquid form onto substrates and treated by rapid thermal processing to form crystalline copper selenide and indium selenide films.

Curtis, Calvin J; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S

2014-11-04

426

A novel method for the assembly of nano-zeolite crystals on porous stainless steel microchannel and then zeolite film growth  

NASA Astrophysics Data System (ADS)

A new method that is simple, efficient, and clean was developed for seeding surfaces with a monolayer of covalently bonded zeolite seeds. This method was used to seed the microchannels fabricated on porous stainless steel with NaA nano-zeolites enabling the deposition and growth of defect-free zeolite film. The NaA nano-zeolites were attached to the surface of the stainless steel via alkoxysilane linkers (e.g., 3-chloropropyltrimethoxysilane and 3-aminopropyltrimethoxysilane) grafted on the stainless steel. The NaA zeolite grown on the microchannel by hydrothermal synthesis consists of intergrown, (1 1 1)-oriented pyramidal NaA crystals that completely clad the stainless steel grains. The zeolite cladding the grains grew uniformly until the zeolite layers of neighboring grain impinges, then intergrew to fully bridge the gaps between the grains forming a defect-free film layer. A separation factor of 10,000 and a flux of 0.04 kg m-2 h-1 were obtained for water pervaporation from a 3 wt% water-benzaldehyde solution at room temperature.

Yang, Guohui; Zhang, Xiongfu; Liu, Shuqin; Yeung, King Lun; Wang, Jinqu

2007-01-01

427

Adsorption and diffusion properties of zeolite membranes by transient permeation  

Microsoft Academic Search

Adsorption isotherms and diffusion coefficients for light gases and butane isomers were measured for the transport pathways involved in gas permeation through H-ZSM-5 membranes by a transient permeation technique. The permeate responses to step changes in the feed were measured, and the transport was modeled as Maxwell—Stefan diffusion with single-site Langmuir adsorption in the zeolite. Isotherms measured for N2, CO2,

Tracy Q. Gardner; John L. Falconer; Richard D. Noble

2002-01-01

428

Characterization of short-time dealumined HZSM-5 zeolites  

Microsoft Academic Search

Temperature-programmed desorption (TPD) of water was applied to characterize short-time dealuminated HZSM-5 zeolites. Using\\u000a a regularization method, distribution functions of the effective desorption energy of water were calculated. The results clearly\\u000a show that during dealumination a new adsorption site is formed which can be attributed to non-framework or transient aluminium\\u000a species. The highest concentration of these sites was observed for

Rita Rosmarie Sattler; W.-D. Einicke; B. Hunger

2004-01-01

429

Hydrothermal synthesis of Al and Ga-substituted Omega zeolite  

Microsoft Academic Search

The synthesis and characterisation of zeolite Al- and Ga-Omega has been studied in the temperature range 383–413 K using tetramethyl ammonium hydroxide as a template. The evidence for framework gallium substitution was obtained from chemical analysis, X-ray diffraction, IR, solid state MAS NMR, thermoanalytical studies and ion exchange. Crystal morphology varied with the degree of isomorphous substitution of both Al

S. P. Mirajkar; M. J. Eapen; S. S. Tamhankar; B. S. Rao; V. P. Shiralkar

1993-01-01

430

Extraction of edingtonite from a natural zeolite under hydrothermal conditions  

NASA Astrophysics Data System (ADS)

In the present study, edingtonite has been extracted from natural zeolite clinoptilolite by simulating the natural hydrothermal conditions in the laboratory, under the influence of solutions with different concentrations of Ba+2 and Na+, varying from 0.5 to 2.8 mol/L, at 150 °C. In this work, the essential hydrothermal conditions have been provided by hydrothermal autoclaves. The natural and laboratory prepared samples were characterized by XRD, XRF and SEM methods.

Tutti, F.; Kamyab, S. M.; Barghi, M. A.; Badiei, A.

2013-01-01

431

The synthesis and characterisation of JBW-type zeolites  

Microsoft Academic Search

Bulk zeolite JBW, Na2K[Al3Si3O12]·0.5H2O, has been synthesised under hydrothermal conditions (225°C) from a solution containing both sodium and potassium ions. The structure has been refined, at room temperature and at 4K, from powder neutron diffraction data. Sodium ions occupy sites in the non-hydrated cristabolite layers while the eight-ring channels contain lines of alternating potassium ions and water molecules. The positions

A. M. Healey; G. M. Johnson; M. T. Weller

2000-01-01

432

Phenoxazine dyes in zeolite L, synthesis and properties  

Microsoft Academic Search

The preparation and characterisation of brightly luminescent dye-zeolite L host–guest microcrystals and of nitro, amino, N-acetyl, and N-alkyl phenoxazine dyes is reported. The synthesis of 3-ethylamino-7-ethyliminophenoxazinium nitrate (9) is based on five steps including simple and highly efficient silver-catalysed oxidation at room temperature, which can also be used to synthesise oxonine (6). 6 and 9 are inserted in about 1.5

Huub Maas; Abderrahim Khatyr; Gion Calzaferri

2003-01-01

433

Synergistic effect of natural zeolites on flame retardant additives  

Microsoft Academic Search

The thermal degradation and flammability of intumescent fire-retardant polypropylene matrix composites consisting of ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER) as a carbonisation agent and natural zeolite (clinoptilolite rich, Gördes II) as a synergistic agent were examined. APP and PER combinations were examined at different ratios (0.25, 0.33, 0.5, 1, 2, 3, and 4) for

H. Demir; E. Ark??; D. Balköse; S. Ülkü

2005-01-01

434

The removal of heavy metal cations by natural zeolites  

Microsoft Academic Search

In this study, the adsorption behavior of natural (clinoptilolite) zeolites with respect to Co2+, Cu2+, Zn2+, and Mn2+ has been studied in order to consider its application to purity metal finishing wastewaters. The batch method has been employed, using metal concentrations in solution ranging from 100 to 400 mg\\/l. The percentage adsorption and distribution coefficients (Kd) were determined for the

E. Erdem; N. Karapinar; R. Donata

2004-01-01

435

Organics\\/water separation by pervaporation with a zeolite membrane  

Microsoft Academic Search

Organic\\/water mixtures are separated at ambient temperature and pressure by pervaporation through a silicalite zeolite membrane supported on the inner surface of a porous stainless-steel cylindrical tube. Methanol, ethanol and acetone were preferentially separated from aqueous solutions. For methanol\\/water separations, a relatively constant separation factor between 11 and 14 was obtained over a wide range of methanol feed concentrations. Total

Q. Liu; R. D. Noble; John L. Falconer; H. H. Funke

1996-01-01

436

Purification of metal electroplating waste waters using zeolites  

Microsoft Academic Search

The sorption behaviour of natural (clinoptilolite) and synthetic (NaP1) zeolites has been studied with respect to Cr(III), Ni(II), Zn(II), Cu(II) and Cd(II) in order to consider its application to purify metal finishing waste waters. The batch method has been employed using metal concentrations in solution ranged from 10 to 200mg\\/l and solid\\/liquid ratios ranged from 2.5 to 10g\\/l. The Langmuir

E Álvarez-Ayuso; A Garc??a-Sánchez; X Querol

2003-01-01

437

Natural Zeolites: Cation Exchange, Cation Arrangement and Dehydration Behavior  

Microsoft Academic Search

Still 50 years ago natural zeolites mainly from vugs and fissures of volcanic rocks were considered a rare curiosity of nature.\\u000a About 100 years ago chemists recognized that these minerals with a tetrahedral framework structure, characterized by internal\\u000a porous space in form of cavities and connecting channels, can be used for ion exchange, molecular sieving, and catalytic reactions.\\u000a Thus in

Thomas Armbruster

438

Generalized statistical model for multicomponent adsorption equilibria on zeolites  

SciTech Connect

The statistical thermodynamic approach to multicomponent adsorption equilibria on zeolites has been extended to nonideal systems, through the correction of cross coefficients characterizing the interaction between unlike molecules. Estimation of the model parameters requires experimental binary equilibrium data. Comparisons with the classical model based on adsorbed solution theory are reported for three nonideal ternary systems. The two approaches provide comparable results in the simulation of binary and ternary adsorption equilibrium data at constant temperature and pressure.

Rota, R.; Gamba, G.; Paludetto, R.; Carra, S.; Morbidelli, M. (Dipartimento di Chimica Fisica Applicata, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (IT))

1988-05-01

439

Tina M. Nenoff Defect-free Thin Film Zeolite Membranes for H2 Separation and IsolationDefect-free Thin Film Zeolite Membranes for H2 Separation and Isolation  

E-print Network

Tina M. Nenoff Defect-free Thin Film Zeolite Membranes for H2 Separation and IsolationDefect-free Thin Film Zeolite Membranes for H2 Separation and Isolation Tina M. Nenoff Distinguished Member Separation Membranes: Introduction Goal: Synthesis of robust microporous zeolite membranes to improve on H2

440

Zeolite confined palladium(0) nanoclusters as effective and reusable catalyst for hydrogen generation from the hydrolysis of ammonia-borane  

Microsoft Academic Search

Zeolite confined palladium(0) nanoclusters were prepared by a two step procedure: incorporation of Pd2+ ions into the zeolite-Y by ion-exchange followed by the reduction of Pd2+ ions in the supercages of zeolite-Y with sodium borohydride at room temperature. Zeolite confined palladium(0) nanoclusters are stable enough to be isolated as solid materials and characterized by ICP-OES, XRD, HRTEM, SEM, X-ray photoelectron

Murat Rakap; Saim Özkar

2010-01-01

441

Synthesis of ZSM-5 type zeolites with and without template and evaluation of physicochemical properties and aniline alkylation activity  

Microsoft Academic Search

ZSM-5 zeolite containing SiO2\\/Al2O3 = 28 was synthesised by hydrothermal process with and without template. Characterisation of the zeolites was done using XRD, IR, NMR, SEM and BET surface area measurements. Acidity of the zeolites was measured by ammonia adsorption-desorption. Catalytic activity of HZSM-5 zeolites was evaluated by aniline alkylation, cumene dealkylation, alkylation of benzene with ethylene and propylene and

S. Narayanan; Asima Sultana; K. Krishna; Paul Mériaudeau; Claude Naccache

1995-01-01

442

Molecular dynamics simulation of pervaporation in zeolite membranes  

NASA Astrophysics Data System (ADS)

The pervaporation separation of liquid mixtures of water/ethanol and water/methanol using three zeolite (Silicalite, NaA and Chabazite) membranes has been examined using the method of molecular dynamics. The main goal of this study was to identify intermolecular interactions between water, methanol, ethanol and the membrane surface that play a critical role in the separations. This would then allow better membranes to be designed more efficiently and systematically than the trial-and-error procedures often being used. Our simulations correctly exhibited all the qualitative experimental observations for these systems, including the hydrophobic or hydrophilic behaviour of zeolite membranes. The simulations showed that, for Silicalite zeolite, the separation is strongly influenced by the selective adsorption of ethanol. The separation factor, as a consequence, increases almost exponentially as the ethanol composition decreases. For ethanol dehydration in NaA and Chabazite, pore size was found to play a very important role in the separation; very high separation factors were therefore possible. Simulations were also used to investigate the effect of pore structure, feed compositions and operating conditions on the pervaporation efficiency. Finally, our simulations also demonstrated that molecular simulations could serve as a useful screening tool to determine the suitability of a membrane for potential pervaporation separation applications. Simulations can cost only a small fraction of an experiment, and can therefore be used to design experiments most likely to be successful.

Jia, W.; Murad, S.

443

CO2 adsorption in amine-grafted zeolite 13X  

NASA Astrophysics Data System (ADS)

The adsorption of CO2 on Zeolite 13X functionalized with amino groups was studied. Adsorbent functionalization was carried out by grafting with different loads of monoethanolamine (MEA). The adsorbents were characterized by N2 adsorption/desorption isotherms at 77 K, x-ray diffraction, TGA, in situ FTIR, XPS and adsorption microcalorimetry. CO2 isotherms were studied in a gravimetric device up to 10 bar at 298 and 348 K. It was found that increasing loads of amine to the adsorbent tend to reduce micropore volume of the resulting adsorbents by pore blocking with MEA. There is experimental evidence that part of the loaded MEA is effectively covalently bonded to the zeolitic structure, whereas there is also physisorbed excess MEA which will eventually be desorbed by raising the temperature beyond MEA boiling point. Heats of adsorption at nearly zero coverage indicate that some of the adsorbed CO2 reacts with available amino groups, which agrees with the finding that the adsorption capacity increases with increasing temperature for the modified zeolite with the highest MEA load.

Bezerra, Diôgo P.; Silva, Francisco W. M. da; Moura, Pedro A. S. de; Sousa, Allyson G. S.; Vieira, Rodrigo S.; Rodriguez-Castellon, Enrique; Azevedo, Diana C. S.

2014-09-01

444

Synthetic zeolites and other microporous oxide molecular sieves  

PubMed Central

Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow “tailoring” of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

Sherman, John D.

1999-01-01

445

Skeletal isomerization of 1-butene on MCM-22 zeolite catalyst  

SciTech Connect

The skeletal isomerization of 1-butene has been studied on two MCM-22 zeolite catalysts synthesized with different Si/Al ratios, i.e., 15 and 47, under a wide range of operating conditions. Product yields are a function of n-butene conversion, and a maximum of isobutene yield is found at ca. 50% conversion. Besides isobutene, propylene and pentanes, which are formed by dimerization-cracking reactions products. Isobutene also takes part, together with the n-butenes, in the formation of by-products thorough dimerization and/or codimerization processes, which would also lead to a lower isobutene selectivity. Moreover, the yield of isobutene increases with increasing reaction temperature and decreasing 1-butene partial pressure, while the contrary holds for the formation of by-products. On the basis of these results the mechanism of formation of isobutene and the different by-products on MCM-22 is discussed. Finally, the selectivity to isobutene is strongly improved by increasing the Si/Al ratio of the zeolite, which is explained by a decrease of the undesired consecutive reactions when decreasing the density of Broensted acid sites of the zeolite. 24 refs., 6 figs., 6 tabs.

Asensi, M.A.; Corma, A.; Martinez, A. [Universidad Politecnica de Valencia (Spain)] [Universidad Politecnica de Valencia (Spain)

1996-02-01

446

Mononuclear Iridium Dinitrogen Complexes Bonded to Zeolite HY.  

PubMed

The adsorption of N2 on structurally well-defined dealuminated HY zeolite-supported iridium diethylene complexes was investigated. Iridium dinitrogen complexes formed when the sample was exposed to N2 in H2 at 298?K, as shown by infrared spectra recorded with isotopically labeled N2 . Four supported species formed in various flowing gases: Ir(N2 ), Ir(N2 )(N2 ), Ir(C2 H5 )(N2 ), and Ir(H)(N2 ). Their interconversions are summarized in a reaction network, showing, for example, that, in the presence of N2 , Ir(N2 ) was the predominant dinitrogen species at temperatures of 273-373?K. Ir(CO)(N2 ) formed transiently in flowing CO, and in the presence of H2 , rather stable iridium hydride complexes formed. Four structural models of each iridium complex bonded at the acidic sites of the zeolite were employed in a computational investigation, showing that the calculated vibrational frequencies agree well with experiment when full calculations are done at the level of density functional theory, independent of the size of the model of the zeolite. PMID:25381885

Yang, Dong; Chen, Mingyang; Martinez-Macias, Claudia; Dixon, David A; Gates, Bruce C

2014-11-01

447

Core-shell strain structure of zeolite microcrystals  

NASA Astrophysics Data System (ADS)

Zeolites are crystalline aluminosilicate minerals featuring a network of 0.3-1.5-nm-wide pores, used in industry as catalysts for hydrocarbon interconversion, ion exchangers, molecular sieves and adsorbents. For improved applications, it is highly useful to study the distribution of internal local strains because they sensitively affect the rates of adsorption and diffusion of guest molecules within zeolites. Here, we report the observation of an unusual triangular deformation field distribution in ZSM-5 zeolites by coherent X-ray diffraction imaging, showing the presence of a strain within the crystal arising from the heterogeneous core-shell structure, which is supported by finite element model calculation and confirmed by fluorescence measurement. The shell is composed of H-ZSM-5 with intrinsic negative thermal expansion whereas the core exhibits a different thermal expansion behaviour due to the presence of organic template residues, which usually remain when the starting materials are insufficiently calcined. Engineering such strain effects could have a major impact on the design of future catalysts.

Cha, Wonsuk; Jeong, Nak Cheon; Song, Sanghoon; Park, Hyun-Jun; Thanh Pham, Tung Cao; Harder, Ross; Lim, Bobae; Xiong, Gang; Ahn, Docheon; McNulty, Ian; Kim, Jungho; Yoon, Kyung Byung; Robinson, Ian K.; Kim, Hyunjung

2013-08-01

448

Novel Zeolitic Imidazolate Framework/Polymer Membranes for Hydrogen Separations in Coal Processing  

SciTech Connect

Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed-matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethylenediamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H2/CO2 selectivity similar to the uncrosslinked polymer.

Musselman, Inga H.

2013-01-31

449

Development of Zeolite Nonwoven for the Adsorption of Radioactive Cesium - 13288  

SciTech Connect

The zeolite nonwoven fabric produced by TDS (Totally Dry System) process has some advantages such as the control of zeolite content, flexibility, strength and water-resistant property depending on the purpose. Hence the zeolite nonwoven fabric is expected for the application in various fields of the decontamination of Cs-contaminated water. In this study, Cs adsorption properties of zeolite nonwoven fabrics were examined by batch experiments, and the radiation stability, thermal stability and chemical durability were evaluated. As for batch adsorption properties, relatively large uptake rate of Cs{sup +} was obtained; the uptake equilibrium attained within 20 min and the uptake (%) was above 95%. The differences in zeolite content had no effects on the Cs{sup +} uptake (%). The uptake (%) of Cs{sup +} in seawater was slightly lowered compared to that in the presence of HNO{sub 3}. The uptake (%) of Cs{sup +} in seawater was estimated to be above 90% after 2 h-shaking, indicating the considerable enhancement of uptake rate compared to the conventional granular zeolites. The uptake (%) of Cs{sup +} for the zeolite high content type was estimated to be above 99% by using {sup 137}Cs tracer. As for the comparison of sealing treatment, the uptake (%) for the zeolite sheet treated with edge sealing was larger than that with rapping treatment. The uptake (%) for the zeolite sheet (zeolite high content type) was estimated to be about 95%, which is independent of sealing treatment and NaOH concentration. As for the stability, the surface morphology and the structure of zeolite sheet were not altered by the treatment with acid and alkaline solutions under the experimental conditions. The zeolite sheets were also stable after {sup 60}Co-? ray irradiation up to 7.01x10{sup 6} R. On the other hand, color change for both fiber and zeolite and the shrinkage of the fiber were observed after heat treatment at 150 deg. C for 2 h. Thus the considerable enhancement of adsorption properties was observed by using zeolite nonwoven fabrics compared to the conventional granular zeolites. (authors)

Murao, Ayako; Nakai, Tomonori; Mimura, Hitoshi [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan)] [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan); Miura, Teruo; Aoyama, Yoshihito [OJI KINOCLOTH K.K., 1-2-5 Iriyamase Fuji-shi, Shizuoka-ken 491-0204 (Japan)] [OJI KINOCLOTH K.K., 1-2-5 Iriyamase Fuji-shi, Shizuoka-ken 491-0204 (Japan)

2013-07-01

450

Human Rights and Behavior Modification  

ERIC Educational Resources Information Center

Criticisms of behavior modification, which charge that it violates ethical and legal principles, are discussed and reasons are presented to explain behavior modification's susceptibility to attack. (GW)

Roos, Philip

1974-01-01

451

Reducing adverse effects from UV sunscreens by zeolite encapsulation: comparison of oxybenzone in solution and in zeolites.  

PubMed

Oxybenzone (OXB) is one of the most widely employed sunscreen ingredients, yet its allowed load is limited to a maximum of 6% reflecting the frequency with which adverse effects are reported. From a spectroscopic point of view, OXB has excellent absorption properties in both the UVB and UVA regions. We propose that zeolite encapsulation can lead to a sunscreen composite ingredient, that we describe as a supramolecular sunscreen, that will retain the excellent spectroscopic properties of OXB, while preventing contact between the skin and the active ingredient. OXB is very photostable, with the only photodegradative pathway observed being the monophotonic photoejection of electrons that leads to trace yields of phenoxyl radicals; this trace reaction is so minor that it cannot be detected from the recovery of unreacted OXB following UV exposure. Solution, as well as powder and in vitro studies of the supramolecular sunscreen, demonstrate that the protective properties of OXB are totally preserved when encapsulated in zeolite NaY. PMID:19930122

Chrétien, Michelle N; Heafey, Eve; Scaiano, Juan C

2010-01-01

452

MFI zeolite nanosponges possessing uniform mesopores generated by bulk crystal seeding in the hierarchical surfactant-directed synthesis.  

PubMed

The synthesis of a mesoporous material with uniform mesopore diameters and crystalline MFI zeolite walls has been achieved, simply by seeding the multiammonium surfactant-directed synthesis with bulk zeolite crystals. The bulk seeds disappeared in the final product. As a result of seeding, the mesoporous zeolites could be generated rapidly even at high Al content. PMID:24633468

Jo, Changbum; Cho, Kanghee; Kim, Jaeheon; Ryoo, Ryong

2014-04-25

453

Self-diffusion in single-file zeolite membranes is Fickian at long times Peter H. Nelson  

E-print Network

Self-diffusion in single-file zeolite membranes is Fickian at long times Peter H. Nelson Department-file Langmuirian zeolites of finite extent, which has been validated by open system kinetic Monte Carlo simulations, suggesting that Fickian self-diffusion dominates transport in longer single-file zeolites. Through

Nelson, Peter Hugo

454

ForReview.Confidential-ACS Catalytic Transformation of 1,3,5 -Trimethyl Benzene over USY Zeolite  

E-print Network

ForReview.Confidential-ACS Catalytic Transformation of 1,3,5 -Trimethyl Benzene over USY Zeolite Catalytic Transformation of 1,3,5 -Trimethyl Benzene over USY Zeolite Catalyst Nasir M. Tukur and Sulaiman investigated over USY zeolite catalyst in a novel riser simulator at different operating conditions. The effect

Al-Khattaf, Sulaiman

455

Zeolite-Induced Solvation Effects on Excited-State Properties of Ru(bpy)3 2+: Implications  

E-print Network

Zeolite-Induced Solvation Effects on Excited-State Properties of Ru(bpy)3 2+: Implications of this donor-acceptor system in zeolite Y retards the back electron transfer as compared to the forward-separated species. In this paper, we evaluate how the properties of the photoexcited zeolite-entrapped Ru(bpy)3 2

Dutta, Prabir K.

456

Emergence of Zeolite Analogs and other Microporous Crystals in an Atomic Lattice Model of Silica and Related Materials  

E-print Network

Emergence of Zeolite Analogs and other Microporous Crystals in an Atomic Lattice Model of Silica with a rich variety of structures including known chalcogenides, zeolite analogs, and layered materials. We and Nanostructures Nanoporous materials such as zeolites have been studied extensively for over 50 years because

Auerbach, Scott M.

457

Synthesis of Single-Walled Carbon Nanotubes from Defined Surface of Silicalite-1 Zeolite and their Photoluminescence Characterizations  

E-print Network

Synthesis of Single-Walled Carbon Nanotubes from Defined Surface of Silicalite-1 Zeolite-0011, Japan 3 Dept. of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan Zeolites (MFI-type) zeolite for supporting catalysts for the growth of single-walled carbon nanotubes (SWNTs

Maruyama, Shigeo

458

Flexibility of ideal zeolite frameworks V. Kapko, C. Dawson, M. M. J. Treacy* and M. F. Thorpe  

E-print Network

Flexibility of ideal zeolite frameworks V. Kapko, C. Dawson, M. M. J. Treacy* and M. F. Thorpe 2010 DOI: 10.1039/c003977b We explore the flexibility windows of the 194 presently-known zeolite frameworks. The flexibility window represents a range of densities within which an ideal zeolite framework

Thorpe, Michael

459

Effects of nonframework metal cations and phonon scattering mechanisms on the thermal transport properties of polycrystalline zeolite LTA films  

E-print Network

properties of polycrystalline zeolite LTA films Abraham Greenstein,1 Yeny Hudiono,2 Samuel Graham,1 of phonon scattering mechanisms on the thermal transport properties of zeolite LTA, via experiment measurements and mechanistic understanding of the thermal transport properties of zeolite materials

Nair, Sankar

460

Further studies of a simple atomistic model of silica: Thermodynamic stability of zeolite frameworks as silica polymorphs  

E-print Network

Further studies of a simple atomistic model of silica: Thermodynamic stability of zeolite stability of zeolite frameworks SOD, LTA, MFI, and FAU as silica polymorphs. We applied the method find that quartz remains the thermodynamically stable polymorph at zeolite synthesis temperatures 400 K

Auerbach, Scott M.

461

Transport of micelles of cationic surfactants through clinoptilolite zeolite Zhaohui Li a,b,*, Du Yuansheng a  

E-print Network

Transport of micelles of cationic surfactants through clinoptilolite zeolite Zhaohui Li a,b,*, Du due to its high cation exchange capacity. The affinity of the zeolite for cations makes it a good), at a solution concentration greater than its critical micelle concentration (CMC), through zeolite columns

Li, Zhaohui

462

Microporous and Mesoporous Materials 91 (2006) 296304 Synthesis and proton conductivity of heteropolyacids loaded Y-zeolite as  

E-print Network

of heteropolyacids loaded Y-zeolite as solid proton conductors for fuel cell applications Mohd Irfan Ahmad a, S of heteropolyacids (HPA) onto Y-zeolite. The synthesis conditions have been optimized to ensure complete loading of HPAs onto Y-zeolite structure. The proton conductivity of the prepared material enhanced

Zaidi, S. M. Javaid

463

Physical Adsorption Analysis of Intact Supported MFI Zeolite Karl D. Hammond, Geoffrey A. Tompsett, Scott M. Auerbach,*,, and  

E-print Network

Physical Adsorption Analysis of Intact Supported MFI Zeolite Membranes Karl D. Hammond, Geoffrey A coefficient in the zeolite and the support. Further, we use the respective adsorption isotherms to determine of the support to zeolite diffusion coefficients. We emphasize that the results are specific to the architecture

Auerbach, Scott M.

464

A Theoretical Investigation of Dimethyl Carbonate Synthesis on Cu-Y Zeolite Xiaobo Zheng and Alexis T. Bell*  

E-print Network

A Theoretical Investigation of Dimethyl Carbonate Synthesis on Cu-Y Zeolite Xiaobo Zheng and Alexis of dimethyl carbonate (DMC) synthesis via oxidative carbonylation of methanol on Cu-exchanged Y zeolite, Cu-3 Cu-exchanged zeolite are known to be active catalysts for oxidative carbonylation of methanol

Bell, Alexis T.

465

Modeling tracer counter-permeation through anisotropic zeolite membranes: from mean eld theory to single-le diffusion  

E-print Network

Modeling tracer counter-permeation through anisotropic zeolite membranes: from mean ®eld theory simulations, tagged and untagged molecules counter-diffuse through zeolite membranes of ®nite thickness. Fick Science S.A. All rights reserved. Keywords: Counter-permeation; Anisotropic zeolite membranes; Mean ®eld

Nelson, Peter Hugo

466

Mechanisms of Hydrogen Exchange of Methane with H-Zeolite Y: An ab Initio Embedded Cluster Study  

E-print Network

Mechanisms of Hydrogen Exchange of Methane with H-Zeolite Y: An ab Initio Embedded Cluster Study exchange of methane with H-Zeolite Y. We found that inclusion of the Madelung field stabilizes with experimental observation. Introduction Zeolites are important technological materials due to their many

Truong, Thanh N.

467

Framework Fe Ions in Fe-ZSM-5 Zeolite Studied by UV Resonance Raman Spectroscopy and Density Functional Theory Calculations  

E-print Network

Framework Fe Ions in Fe-ZSM-5 Zeolite Studied by UV Resonance Raman Spectroscopy and Density metal containing zeolites show high selectivity and activity in many catalytic reactions under mild sites remain elusive. Here, we present a study of the framework Fe ions in Fe-ZSM-5 zeolite via

Li, Weixue

468

Na-A (LTA) zeolite synthesis directly from alumatrane and silatrane by sol-gel microwave techniques  

E-print Network

Na-A (LTA) zeolite synthesis directly from alumatrane and silatrane by sol-gel microwave techniques 2002; accepted 7 August 2002 Abstract Na-A (1 mm crystal size) zeolite was successfully synthesized via large crystallite sizes ($4.5 mm). The analyzed Si:Al:Na ratio of synthe- sized Na-A zeolite is 1

Gulari, Erdogan

469

High-throughput chemical modification of oligonucleotides for systematic structure-activity relationship evaluation.  

PubMed

Chemical modification of siRNA is achieved in a high-throughput manner (96-well plate format) by copper catalyzed azide-alkyne cycloadditions. This transformation can be performed in one synthetic operation at up to four positions with complete specificity, good yield, and acceptable purity. As demonstrated here, this approach extends the current synthetic options for oligonucleotide modifications and simultaneously facilitates the systematic, rapid biological evaluation of modified siRNA. PMID:25398098

Zewge, Daniel; Gosselin, Francis; Kenski, Denise M; Li, Jenny; Jadhav, Vasant; Yuan, Yu; Nerurkar, Sandhya S; Tellers, David M; Flanagan, W Michael; Davies, Ian W

2014-12-17

470

Methylation of phenol over high-silica beta zeolite: Effect of zeolite acidity and crystal size on catalyst behaviour  

Microsoft Academic Search

A systematic investigation was carried out to elucidate several aspects of the gas\\/solid methylation of phenol over high Si\\/Al ratio beta-structured zeolite in protonated form, characterised by various techniques, including XRD, SEM, BET, ICP, FTIR, TGA, microcalorimetry, and modeling by ab initio calculations. Data on the characteristics and the kinetic and mechanistic features of the catalytic reaction, as well as

M. Bregolato; V. Bolis; C. Busco; P. Ugliengo; S. Bordiga; F. Cavani; N. Ballarini; L. Maselli; S. Passeri; I. Rossetti; L. Forni

2007-01-01

471

Dissolution kinetics of synthetic zeolite NaP1 and its implication to zeolite treatment of contaminated waters.  

PubMed

The effect of pH on the dissolution kinetics of NaP1 zeolite, which was produced from the alkaline treatment of coal fly ash and may be used for decontamination of acid mine waters, is studied. The sample contains considerable amounts of accessory phases that partly dissolve during the experiment. Therefore, the dissolution rate was estimated during a stage in which the Al/Si ratio was equal to that of NaP1 (0.6). The release rate of these elements is controlled by the dissolution of the zeolite itself during this stage. The dissolution rate of NaP1 slows down with increasing pH in the acidic range, becomes constant at an intermediate pH, and increases with increasing pH in the basic range. The observed changes in rates were described using a rate law based on a surface speciation model. Using this rate law, we calculated the half-life of NaP1 to be about 2 years at near neutral pH and less than 10 days at pH below 3. For the utilization of NaP1 in the treatment of wastewaters or acid mine waters, these short half-lives bear two implications: (1) The treated waters must be kept at near neutral pH, and NaP1 should be added periodically to the treated waters in order to compensate for zeolite loss. (2) In water treatment applications that require a relatively short reaction time, the zeolite removed from the effluents should be kept dry in order to avoid its decomposition and the consequent release of the adsorbed metal to the environment. PMID:16053086

Cama, Jordi; Ayora, Carles; Querol, Xavier; Ganor, Jiwchar

2005-07-01

472

Photoinduced electron transfers in zeolites: impact of the aluminum content on the activation energies.  

PubMed

We report the activation energy determination corresponding to the recombination of the radical cation electron moiety created through photoionization of the 1,6-diphenyl-1,3,5-hexatriene molecule incorporated in ZSM-5 zeolite channels. We demonstrate that the charge separated state stabilization in zeolite does not depend only on the Al content but also on the Al repartition. PMID:22833151

Hureau, Matthieu; Moissette, Alain; Gaillard, Jeremy; Brémard, Claude

2012-10-01

473

ZSM-5, Y, and Mordenite Zeolites as Sensing Materials for Ethanol Vapor  

NASA Astrophysics Data System (ADS)

The effects of the framework type, the charge balancing cation type, and the Si/Al ratio of ZSM-5, Y, and Mordenite zeolites on the electrical conductivity responses towards ethanol vapor have been investigated. All zeolites were characterized using XRD, FT-IR, SEM, TGA, BET, and NH3-TPD techniques. For the effect of the framework type, H^+Y has a higher electrical conductivity sensitivity value than that of H^+MOR because of a greater pore volume and available surface area. For the effect of the charge balancing cation, all NH4^+ZSM-5 zeolites (Si/Al = 23, 50, 80, 280) show negative responses, whereas the H^+Y zeolites (Si/Al = 30, 60, 80) and the H^+MOR zeolites (Si/Al = 30, 200) show positive responses. These differing behaviors can be traced to the interactions between ethanol molecules and the reactive sites of the zeolites. For the effect of Si/Al ratio, the electrical conductivity sensitivity towards the ethanol decreases with increasing Si/Al ratio or decreasing Al content, and there is a lesser degree of interaction between ethanol molecules and the active sites of the zeolites. The interactions between the ethanol molecules and the zeolites were investigated through infrared spectroscopy.

Sirivat, Anuvat; Yimlamai, Intira

2011-03-01

474

Catalytic Transformation of Toluene over High Acidity Y-Zeolite Based S. Al-Khattaf*  

E-print Network

Catalytic Transformation of Toluene over High Acidity Y-Zeolite Based Catalyst S. Al Abstract Catalytic transformation of toluene has been investigated over Y-zeolite based catalysts of the reported studies on toluene disproportionation have been conducted at relatively high pressure

Al-Khattaf, Sulaiman

475

Adsorption characteristics of surfactants and phenol on modified zeolites from their aqueous solutions  

Microsoft Academic Search

Adsorption characteristics of anion-, cation- and nonion-type surfactants and phenol from their aqueous solution on Na-Y zeolites modified by SiCl4 treatment and NA-ZSM-5 zeolites with several Si\\/Al ratios were measured. Surfactants used were sodium dodecylbenzenesulfonte (DBS), laurylpyridinium chloride (LPC), polyoxyethylenenonylphenylether (POENPE) and phenol.

T. Kawai; K. Tsutsumi

1995-01-01

476

Evaluation of zeolites synthesized from fly ash as potential adsorbents for wastewater containing heavy metals.  

PubMed

The pure-form zeolites (A and X) were synthesized by applying a two-stage method during hydrothermal treatment of fly ash prepared initial Cu and Zn gel. The difference of adsorption capacity of both synthesized zeolites was assessed using Cu and Zn as target heavy metal ions. It was found that adsorption capacity of zeolite A showed much higher value than that of zeolite X. Thus, attention was focused on investigating the removal performance of heavy metal ions in aqueous solution on zeolite A, comparing with zeolite HS (hydroxyl-solidate) prepared from the residual fly ash (after synthesis of pure-form zeolite A from fly ash) and a commercial grade zeolite A. Batch method was used to study the influential parameters of the adsorption process. The equilibrium data were well fitted by the Langmuir model. The removal mechanism of metal ions followed adsorption and ion exchange processes. Attempts were also made to recover heavy metal ions and regenerate adsorbents. PMID:19402411

Wang, Chunfeng; Li, Jiansheng; Sun, Xia; Wang, Lianjun; Sun, Xiuyun

2009-01-01

477

Hydrocarbon cracking selectivities with a dual zeolite fluid cracking catalyst containing REY and ZSM-5  

Microsoft Academic Search

Synthetic Y faujasite zeolites have been used commercially as cracking catalysts for the past two decades, and more recently dual zeolite fluid cracking catalysts, containing faujasite and ZSM-5 were discovered to increase the octane number of the gasoline during catalytic cracking of gas oil. This concept, where ZSM-5 constitutes only a small fraction (about 1 wt %) of the cracking

K. Rajagopalan; G. W. Young

1987-01-01

478

Exhausted fluid catalytic cracking catalysts as raw materials for zeolite synthesis  

Microsoft Academic Search

The utilization of exhausted fluid catalytic cracking (FCC) catalysts as raw materials for the zeolite synthesis was analyzed. Samples of the catalysts directly released from FCC units and the corresponding impact grinding pretreated samples were used. Mechanical treatment was observed to decrease catalyst crystallinity and particle size. The catalyst reactivity was analyzed in terms of conversion in zeolite and product

Elena I. Basaldella; Julio C. Paladino; Mariana Solari; Graciela M. Valle

2006-01-01

479

Synthesis and characterisation of MFI-type zeolites supported on carbon materials  

Microsoft Academic Search

A wide variety of silicalite\\/carbon and ZSM-5\\/carbon composites have been prepared by conventional hydrothermal synthesis. The influence of the surface chemistry and porosity of the carbon supports on the growth of the zeolite has been studied. The presence of oxygen surface groups on the carbon supports has been found to be necessary to allow the anchorage of the zeolite layer

J. Garc??a-Mart??nez; D. Cazorla-Amorós; A. Linares-Solano; Y. S. Lin

2001-01-01

480

Synthesis, characterisation, and adsorption evaluation of carbon-natural-zeolite composites  

Microsoft Academic Search

Natural zeolite is well known for the removal of heavy metals and has wide spread applications, however it has a negligible adsorption capacity for organic contaminants from aqueous solution. Several composites of carbon and natural zeolite with varying amounts of carbon were synthesised as prospective adsorbents to adsorb organic contaminants from waste water. The composites were prepared by saturating a

Pradeep R. Shukla; Shaobin Wang; H. M. Ang; Moses O. Tadé

2009-01-01