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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

Copper removal using bio-inspired polydopamine coated natural zeolites.  

PubMed

Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2-5.5), PDA treatment time (3-24h), contact time (0 to 24h) and initial Cu(II) ion concentrations (1 to 500mgdm(-3)) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93mgg(-1) for pristine natural zeolite and 28.58mgg(-1) for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01M or 0.1M) of either acid or base. PMID:24731937

Yu, Yang; Shapter, Joseph G; Popelka-Filcoff, Rachel; Bennett, John W; Ellis, Amanda V

2014-05-30

3

The nature of 'overexchanged' copper and platinum on zeolites.  

PubMed

The uptake of platinum and copper tetra-ammine (PTA and CTA, [(NH(3))(4)Pt](2+) and [(NH(3))(4)Cu](2+)) into zeolites was compared over silica and three zeolites (Y, MOR and MFI) with different points of zero charge and aluminium content. Adsorption was determined as a function of pH at several metal concentrations, and pH shifts relative to metal free control experiments were carefully monitored. The uptake of both metal ammine complexes onto silica is well described by electrostatic adsorption. We suggest that the metal cations interact with zeolites by two mechanisms, ion exchange at the Al exchange sites and electrostatic adsorption at silanol groups. The former is the dominant mechanism at low to mid pH, and the latter at high pH. This effect is most clearly manifested in zeolites with low aluminium content such as ZSM5; electrostatic adsorption at high pH in ZSM5 yields metal loadings much in excess of the ion exchange capacity and so gives rise to 'overexchange'. Differences between PTA and CTA can be explained by the weaker stability of the CTA complex and its response to the decrease in local pH near the adsorption plane of low PZC zeolites. This change in local pH near oxide surfaces is characteristic of electrostatic adsorption. As the local pH decreases, the CTA ion is probably converted to a dimerized copper complex, perhaps Cu(2)(OH)(2)(2+). A portion of the released ammonia is protonated, increasing the solution pH. In high PZC, high aluminium zeolites with high ion exchange capacity, there is relatively little contribution from electrostatic adsorption. PMID:21727480

Schreier, Marc; Teren, Sarah; Belcher, Latonia; Regalbuto, John R; Miller, Jeffrey T

2005-07-01

4

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

5

Effect of copper cation on the adsorption of nitrosamines in zeolite  

NASA Astrophysics Data System (ADS)

Removal of carcinogens such as nitrosamines in environment is one of the potential applications of zeolites in life science, which involves the molecular reorganization and selective adsorption. To explore how copper species promote the adsorption of volatile nitrosamines in zeolite, NaY was chosen as the host to be modified with copper cation through ion exchange and impregnation. The instantaneous adsorption of N-nitrosopyrrolidine (NPYR) was used to assess the actual capture of nitrosamines by the modified zeolite in order to reveal the relation between the location of the copper cation and its promotion on the adsorption of nitrosamines. As the results revealed, incorporation of copper species in zeolite strengthened the electrostatic interaction between the nitrosamines and the adsorbent but occupies the space inside the channel to cause hindrance. According to the study, the promotion of the copper species overcame their negative effect and desorption of volatile nitrosamines from zeolite at 453 K was thus suppressed. Rather, the copper species dispersed in the channel of zeolite played the main role to improve adsorption of volatile nitrosamines.

Gu, Fang Na; Zhuang, Ting Ting; Cao, Yi; Zhou, Chun Fang; Zhu, Jian Hua

2008-11-01

6

DFT calculations of EPR parameters for copper(II)-exchanged zeolites using cluster models.  

PubMed

The coordination environment of Cu(II) in hydrated copper-exchanged zeolites was explored through the use of density functional theory (DFT) calculations of EPR parameters. Extensive experimental EPR data are available in the literature for hydrated copper-exchanged zeolites. The copper complex in hydrated copper-exchanged zeolites was previously proposed to be [Cu(H(2)O)(5)OH](+) based on empirical trends in tetragonal model complex EPR data. In this study, calculated EPR parameters for the previously proposed copper complex, [Cu(H(2)O)(5)OH](+), were compared to model complexes in which Cu(II) was coordinated to small silicate or aluminosilicate clusters as a first approximation of the impact of the zeolitic environment on the copper complex. Interpretation of the results suggests that Cu(II) is coordinated or closely associated with framework oxygen atoms within the zeolite structure. Additionally, it is proposed that the EPR parameters are dependent on the Si/Al ratio of the parent zeolite. PMID:20000556

Ames, William M; Larsen, Sarah C

2010-01-14

7

Studies on natural STI zeolite: modification, structure, adsorption and catalysis  

Microsoft Academic Search

A natural STI zeolite discovered in China was identified as a calcium-rich and stellerite-isotype zeolite of stilbite with high crystallinity and an open pore system. Both ion exchange and dealumination can stabilize the framework of the zeolite. The structural properties of the parent and the modified STI zeolites were investigated by X-ray diffraction (XRD), thermogravimetric\\/differential thermogravimetric\\/differental thermal analysis (TG\\/DTG\\/DTA), Fourier

Jun Li; Jin Qiu; Yaojun Sun; Yingcai Long

2000-01-01

8

Effects of novel silane modification of zeolite surface on polymer chain rigidification and partial pore blockage in polyethersulfone (PES)–zeolite A mixed matrix membranes  

Microsoft Academic Search

A novel silane coupling agent, (3-aminopropyl)-diethoxymethyl silane (APDEMS) was used in this work to modify zeolite surface for mixed matrix membranes (MMMs). Both elementary analysis and XPS spectra confirm the chemical modification, while BET measurements show no changes in zeolite surface area and total pore volume after the modification. Polyethersulfone (PES)–zeolite 3A, 4A and 5A MMMs were fabricated at high

Yi Li; Huai-Min Guan; Tai-Shung Chung; Santi Kulprathipanja

2006-01-01

9

Zeolite-encapsulated copper (II) complexes with N 3O 2 Schiff bases: synthesis and characterization  

Microsoft Academic Search

Copper(II) complexes with N3O2 Schiff base ligands[B: bis-(acetylacetone)-3-amino-bis(propylenediimine) = H2(acac)2trien; C: bis-(acetylacetone)-3-methylamino-bis(propylenediimine) = H2(acac)2Metrien] were encapsulated in the supercages of zeolite Y in a two-step process: (i) adsorption of copper(II) acetylacetonate in the supercage of the zeolite; (ii) in-situ Schiff base condensation of the copper(II) acetylacetonate complex with corresponding triamine. The resulting materials were purified by Soxhlet extraction. Bulk and

I. Neves; C. Freire; A. N. Zakhárov; B. de Castro; J. L. Figueiredo

1996-01-01

10

Coreactant-induced modifications of catalytic behavior in zeolitic systems  

SciTech Connect

The complex feed processing over zeolite catalysts, competitive reaction between the feed components results in observed rates and selectivities that cannot be predicted from pure component data alone. Hydroisomerization of paraffins over various Pt/zeolites in the presence of an aromatic cofeed is considered as an illustration. The aromatic affects paraffin reaction rates by occupying catalytic sites and perhaps also by partially blocking the pores. Analysis of Arrhenius plots helps in correlations of zeolite structure and the extent to which the paraffin reaction is affected. It is shown that the coreactant can induce selectivity to a zeolite that would otherwise not be shape selective.

Martin, A.M.; Chen, J.-K.; John, V.T. (Dept of Chemical Engineering, West Virginia Univ, Morgantown, WV (US))

1989-11-01

11

Immobilization of copper Schiff base complexes in zeolite matrix: Preparation, characterization and catalytic study  

Microsoft Academic Search

New zeolite-immobilized hybrid catalysts Cu(NO2-salen)–NaY have been prepared by encapsulating copper(II) Schiff base complexes [where NO2-salenH2 is N,N?-(ethylene)-bis-(5-nitro-salicylaldiimine)] in NaY zeolite matrix. The hybrid materials have been characterized by UV–vis, IR and EPR spectrometry and by X-ray powder diffraction analysis. The neat copper(II) Schiff base complex [Cu(NO2-salen)(EtOH)] (1) has also been synthesized and characterized. A brilliant color change (green–gray) has

Buddhadeb Dutta; Sreyashi Jana; Rajesh Bera; Pratap Kumar Saha; Subratanath Koner

2007-01-01

12

Zeolites.  

National Technical Information Service (NTIS)

Zeolites are naturally occurring aluminosilicate minerals. They have 3- dimensional framework structures of interconnected channels and cages that contain exchangeable alkali and alkaline earth cations and adsorbed water. Like phyllosilicates, zeolites ha...

D. W. Ming J. L. Boettinger

2001-01-01

13

The effect of zeolites on copper uptake by plants growing in contaminated soils  

Microsoft Academic Search

Three-year pot experiments were carried out in a greenhouse with the aim of reducing the copper content in the 2nd link of the soil-plant-animal (man) trophic chain. For this purpose, synthetic zeolites of the 3A, 4A, 5A and 13X type were introduced into copper contaminated soils at levels of 1, 2 and 3% by weight in relation to the soil

Barbara Gworek

1993-01-01

14

Controlling the orientation and coverage of silica-MFI zeolite films by surface modification  

NASA Astrophysics Data System (ADS)

The silica-MFI (Si-MFI) zeolite films are fabricated on ?-Al 2O 3 supported silica-zirconia layers. The roughness and chemistry of the substrate surface are changed by surface modification with hydrogen peroxide and carboxymethyl chitosan (CMCS) solution to investigate their effects on the formation and orientation control of Si-MFI zeolite films. The AFM images reveal that the roughness of the silica-zirconia surface can be increased under the treatment of hydrogen peroxide. The Si-MFI zeolite films grown on the rough substrate surface are also b-oriented. Diffuse-reflectance FT-IR studies demonstrate that the abundance of functional groups such as -OH and -COOH can be successfully seeded onto the ?-Al 2O 3 supported silica-zirconia layer through modification with CMCS solution. Continuous b-oriented Si-MFI zeolite films can be fabricated on the CMCS-modified ?-Al 2O 3 supported silica-zirconia layer. It is evident that the orientation and microstructure of Si-MFI zeolite films on ?-Al 2O 3 supported silica-zirconia layers are dominantly controlled by the chemical nature of the substrate surface, where the functional groups serve as the structure-directing matrix to induce the orientation and growth of the zeolite crystals with their b-axes perpendicular to the substrate surface.

Lang, Lin; Liu, Xiufeng; Zhang, Baoquan

2009-02-01

15

Improving the ammonium ion uptake onto natural zeolite by using an integrated modification process.  

PubMed

Detailed investigation on the development of physical and chemical properties of a natural calcium-rich zeolite modified by an integrated process, as well as the relation between the development and ammonium ion uptake (AIU), was conducted. This process consisted of pretreatment (grinding and sieving), sodium salt modification and calcination. Both pretreatment and salt modification largely increased BET surface area, total pore volume and average pore diameter of the raw zeolite. Individual calcination at temperature above 150 degrees C caused framework collapse, losses of partial clinoptilolite and production of X-ray amorphous material, resulting in pore blockage and the decreases in pore volume and BET surface area. However, the introduction of sodium ion enhanced the heat resistance of the raw material from 150 to 400 degrees C, and Na(+) ion treatment followed by calcination could effectively improved pore and surface properties of zeolite, thus leading to the significant enhancement in ammonium ion exchange and adsorption capabilities. PMID:19135300

Liang, Zhu; Ni, Jinren

2009-07-15

16

Bis(hinokitiolato)copper(II): modification (III).  

PubMed

Bis(hinokitiolato)copper(II), Cu(hino)(2), exhibits both antibacterial and antiviral properties, and has been previously shown to exist in two modifications. A third modification has now been confirmed, namely tetrakis(mu(2)-3-isopropyl-7-oxocyclohepta-1,3,5-trien-1-olato)bis(3-isopropyl-7-oxocyclohepta-1,3,5-trien-1-olato)tricopper(II)-bis(mu(2)-3-isopropyl-7-oxocyclohepta-1,3,5-trien-1-olato)bis[(3-isopropyl-7-oxocyclohepta-1,3,5-trien-1-olato)copper(II)] (1/1), [Cu(C(10)H(11)O(2))(2)](3).[Cu(C(10)H(11)O(2))(2)](2), where 3-isopropyl-7-oxocyclohepta-1,3,5-trien-1-olate is the systematic name for the hinokitiolate anion. This new modification is composed of discrete [cis-Cu(hino)(2)](2)[trans-Cu(hino)(2)] trimers and [cis-Cu(hino)(2)](2) dimers. The Cu atoms are bridged by mu(2)-O atoms from the hinokitiolate ligands to give distorted square-pyramidal and distorted octahedral Cu(II) coordination environments. Hence, the Cu(II) environments are CuO(5)/CuO(6)/CuO(5) for the trimer and CuO(5)/CuO(5) for the dimer. Each trimer and dimer has crystallographically imposed inversion symmetry. The trimer has never been observed before, the dimer has been seen only once before, and the combination of the two together in the same lattice is unprecedented. The CuO(5) cores exhibit four strong basal Cu-O bonds [1.915 (2)-1.931 (2) A] and one weak apical Cu-O bond [2.652 (2)-2.658 (2) A]. The CuO(6) core exhibits four strong equatorial Cu-O bonds [1.922 (2)-1.929 (2) A] and two very weak axial Cu-O bonds [2.911 (3) A]. The bite angles for the chelating hinokitiolate ligands range from 83.13 (11) to 83.90 (10) degrees . PMID:20522935

Ho, Douglas M

2010-06-01

17

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

18

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

19

Internal surface modification of zeolite MFI particles and membranes for gas separation  

NASA Astrophysics Data System (ADS)

Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. I synthesized MFI membranes with [h0h] out-of-plane orientation on ?-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH 4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores. The CO2/CH 4 permeation selectivity was close to the Knudsen selectivity (0.6) for the membranes before modification. CO2/CH4 selectivity increased for MFI/benzenemethanol modified membrane (1.0), whereas it decreased for the MFI/2-[(2-aminoethyl)amino]ethanol modified membrane (0.5). MFI/benzenemethanol crystals were shown to have a highest sorption capacity for CH4, whereas, MFI/2-[(2-aminoethyl)amino]ethanol crystals were shown to have a highest sorption capacity for CO2 over all other studied molecules Higher sorption of CH4 in MFI/benzenemethanol and higher sorption of CO2 in MFI/2-[(2-aminoethyl)amino]ethanol and their strong binding to the modified membrane are likely the reasons for observing higher and lower CO2/CH4 permeation selectivity respectively, compared to bare MFI membrane. A further detailed fundamental study of the CO2 adsorption mechanism in modified zeolites is necessary to gain a better understating of the adsorption and permeation behavior of such materials. For the organic molecules with only one functional group (1-butanol, benzenemethanol, and 1-propaneamine), physical adsorption was found - as intuitively expected - to be the only observed mode of attachment of CO2 to the modified zeolite material. Even in the case of MFI modified with 1,3-diaminopropane, only physical adsorption is seen. This is explained by the isolated nature of the amine groups in the material, due to which only a single amine group can interact with a CO2 molecule. On the other hand, chemisorbed CO2 species are clearly observed on bare MFI, and on MFI modified with 3-amino-1-propanol or 2-[(2-aminoethyl)amino]ethanol. Specifically, these are carbonate-like species that arise from the chemisorption of CO2 to the silanol group in bare MFI and the alcohol groups of the modifying molecule. The possibility of significant contributions from external surface silanol groups in adsorbing CO2 chemisorbed species was ruled out by a comparative examination of the FTIR spectra of 10 ?m and 900 nm MFI particles modified with 2-[(2-aminoethyl)amino]ethanol. (Abstract shortened by UMI.).

Kassaee, Mohamad H.

20

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

21

Internal surface modification of MFI-type zeolite membranes for high selectivity and high flux for hydrogen.  

PubMed

MFI-type zeolite membranes were modified by depositing molecular silica at a small number of active sites in the internal surface by in situ catalytic cracking of silane precursor. The limited silica deposition reduced the effective size of the zeolitic channels that dramatically enhanced the H(2) selectivity without causing a large increase in H(2) transport resistance. The modified zeolite membrane achieved an extraordinary H(2)/CO(2) permselectivity of 141 with a high H(2) permeance of 3.96 x 10(-7) mol/m(2) x s x Pa at 723 K. The effect of pore modification on the gas transport behavior was studied on the basis of single gas permeation data. PMID:19397346

Tang, Zhong; Dong, Junhang; Nenoff, Tina M

2009-05-01

22

Stable copper-zeolite filter media for bacteria removal in stormwater.  

PubMed

Cu(2+)-exchanged zeolite (ZCu) as antibacterial media shows great potential for bacteria removal from stormwater, but its stability in high salinity water needs attention. In this study, stable antibacterial media were developed by modifying ZCu through calcination and in situ Cu(OH)2 coating. Their stability and Escherichia coli removal efficiency along with impact of salinity were examined in gravity-fed columns. While copper leaching from ZCu was 20mg/L in test water of salinity 250?S/cm, it was reduced by over 97% through Cu(OH)2 coating and/or calcination. ZCu coated with Cu(OH)2 followed by heat treatment at 180°C (ZCuCuO180) exhibited more consistent E. coli removal (1.7-2.7 log) than ZCu (1.2-3.3 log) in test water of varied salinity but constant contact time 22min. ZCu calcined at 400°C (ZCu400) effectively inactivated removed bacteria during 24h drying period. In the presence of native microbial communities, new sand filters, particularly those having ZCu400 at the top to inactivate bacteria during drying periods and ZCuCuO180 midway to capture and inactivate microbes during wet events, provided the best bacterial removal (1.7 log, contact time 9min). Copper leaching from this design was 9?g/L, well below long-term irrigation standard of 200?g/L. PMID:24747698

Li, Ya L; McCarthy, David T; Deletic, Ana

2014-05-30

23

Kinetics and thermodynamics of copper ions removal from wastewater by use of zeolite  

Microsoft Academic Search

Natural Bulgarian zeolite was tested for its ability to remove Cu2+ from model wastewater. Influence of process variables was investigated. It was found that the optimum wastewater to zeolite ratio is 100:1 and the optimum pH value of water to be treated is 5.5 to 7.5. Zeolite with finer particles shows a higher uptake capacity. The simultaneous presence of Ca2+

M. I. Panayotova

2001-01-01

24

Corrosion resistance properties of superhydrophobic copper surfaces fabricated by one-step electrochemical modification process  

NASA Astrophysics Data System (ADS)

Superhydrophobic copper surfaces have been prepared by a one-step electrochemical modification process in an ethanolic stearic acid solution. In this work, the corrosion properties of hydrophobic copper surface and superhydrophobic copper surfaces were analyzed by means of electrochemical analyses and compared with that of as-received bare copper substrate. The decrease of corrosion current density (icorr) as well as the increase of polarization resistance (Rp) obtained from potentiodynamic polarization curves revealed that the superhydrophobic film on the copper surfaces improved the corrosion resistance performance of the copper substrate.

Huang, Ying; Sarkar, D. K.; Gallant, Danick; Chen, X.-Grant

2013-10-01

25

Modification on natural clinoptilolite zeolite for its NH 4 + retention capacity  

Microsoft Academic Search

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

Vinay Kumar Jha; Shigeo Hayashi

2009-01-01

26

The contributions of morphological and surface chemical modifications to the elevated-temperature ageing of copper–epoxy interfaces  

Microsoft Academic Search

Adhesion experiments were performed using both morphological and surface chemical modifications to identify whether one is dominant in controlling copper–epoxy adhesion and durability. Surface preparation procedures included sanding and etching copper surfaces which were thermally oxidized and a surface plating treatment that formed oxidized nodules on the copper surface. Further surface chemical modification used benzotriazole primary and chromium ion implantation

B. J Love; P. F Packman

1998-01-01

27

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

28

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

29

Influence of copper modifying additive on state of gold in zeolites  

NASA Astrophysics Data System (ADS)

The influence of copper modifying additive on state of gold in NaY and NH 4-mordenite has been investigated. The presence of copper in Au/Cu/NM permits to stabilize fine gold particles (˜8 nm), while for Au/Cu/NaY large particles with unusual complex structure and size up to 80 nm were registered. Furthermore, copper favors the formation of gold particles at low temperature. It was revealed the interaction of gold with copper to facilitate the activation of sites at low temperature due to change of redox and electronic properties of gold species. Gold clusters or gold species with strong chemical interaction with copper ions are active in CO oxidation at low temperature being sensitive to sample pretreatment. Gold nanoparticles are active at high temperature and are less sensitive to reaction conditions.

Smolentseva, E.; Bogdanchikova, N.; Simakov, A.; Pestryakov, A.; Tusovskaya, I.; Avalos, M.; Farías, M. H.; Díaz, J. A.; Gurin, V.

2006-09-01

30

Topotactic conversion of ?-helix-layered silicate into AST-type zeolite through successive interlayer modifications.  

PubMed

AST-type zeolite with a plate morphology can be synthesized by topotactic conversion of a layered silicate (?-helix-layered silicate; HLS) by using N,N-dimethylpropionamide (DPA) to control the layer stacking of silicate layers and the subsequent interlayer condensation. Treatment of HLS twice with 1)?hydrochloric acid/ethanol and 2)?dimethylsulfoxide (DMSO) are needed to remove interlayer hydrated Na ions and tetramethylammonium (TMA) ions in intralayer cup-like cavities (intracavity TMA ions), both of which are introduced during the preparation of HLS. The utilization of an amide molecule is effective for the control of the stacking sequence of silicate layers. This method could be applicable to various layered silicates that cannot be topotactically converted into three-dimensional networks by simple interlayer condensation by judicious choice of amide molecules. PMID:24431158

Asakura, Yusuke; Takayama, Ryosuke; Shibue, Toshimichi; Kuroda, Kazuyuki

2014-02-10

31

Surface modification of Mg 2Ni alloy in an acid solution of copper sulfate and sulfuric acid  

Microsoft Academic Search

A simple method of electroless copper plating for the surface modification of Mg2Ni alloy has been described in this paper. The plating solution contains only copper sulfate and sulfuric acid which are less toxic to the environment than the chemical reagents used in conventional copper plating solutions. Moreover, the coating process was very easy and fast to operate needing no

C. Y Wang; P Yao; D. H Bradhurst; H. K Liu; S. X Dou

1999-01-01

32

Synthesis, characterization and catalytic activity of copper(II) complexes of 14-membered macrocyclic ligand; 3,10-dialkyl-dibenzo-1,3,5,8,10,12-hexaazacyclotetradecanel\\/zeolite encapsulated nanocomposite materials  

Microsoft Academic Search

Nanodimensional microreactor containing (3,10-dialkyl-dibenzo-1,3,5,8,10,12-hexaazacyclotetradecane)copper(II) complexes have been prepared by the one-pot template synthesis of formaldehyde and 1,2-phenylenediamine (1,2-phen) with alkyl and benzyl amine within the pores of zeolite-Y. The copper(II) complexes were entrapped in the supercage of Y-zeolite by a two-step process in the liquid phase: (i) inclusion of a copper(II) precursor complex, [Cu(1,2-phen)2]2+-NaY, and (ii) template condensation of the

Masoud Salavati-Niasari; Fatemeh Davar

2006-01-01

33

Surface modification of a granular activated carbon by citric acid for enhancement of copper adsorption  

Microsoft Academic Search

In this study, citric acid was used to modify a commercially available activated carbon to improve copper ion adsorption from aqueous solutions. The carbon was modified with 1.0 M citric acid, followed by an optional step of reaction with 1.0 M sodium hydroxide. It was found that the surface modification reduced the specific surface area by 34% and point of

J. Paul Chen; Shunnian Wu; Kai-Hau Chong

2003-01-01

34

Localized corrosion effects and modifications of acidic and alkaline slurries on copper chemical mechanical polishing  

NASA Astrophysics Data System (ADS)

This study demonstrates the CMP performance can be enhanced by modifying the corrosion effects of acidic and alkaline slurries on copper. A corrosion test-cell with a polishing platform is connected with the potentiostat to investigate the corrosion behaviors of copper CMP in various alumina slurries. Experiments show that the slurry needs to be maintained in acidic pH<4.56 or alkaline pH>9.05 surroundings and thus better dispersion of alumina particles and less residual contaminant on copper surface can be obtained. The surface defects after copper CMP using acidic and alkaline slurries are described by pitting corrosion mechanisms, and these mechanisms can be regarded as a basis to modify their corrosion effects. Experimental results indicate that it is necessary to modify the dissolution of HNO 3 and oxidization of NH 4OH for copper CMP slurries. Consequently, the slurries of 5 wt.% HNO 3 by adding 0.1 wt.% BTA or 5 wt.% KNO 3 by adding 1 wt.% NH 4OH achieve good CMP performance for copper with higher CMP efficiency factor (CMPEF), 1460 and 486, and lower surface roughness ( Rq), 4.019 and 3.971 nm, respectively. It is found that AFM micrographs can support the effectiveness of corrosion modifications for copper CMP in various slurry chemistries.

Tsai, Tzu-Hsuan; Yen, Shi-Chern

2003-04-01

35

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

PubMed

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 maximal amount of sulfonamides adsorbed was 18-26% DW of dry zeolite weight, as evidenced by thermogravimetric analyses and accounted for about one antibiotic molecule per zeolitic cage. The presence of this organic inside the cage was revealed by unit cell parameter variations and structural deformations obtained by X-ray structure analyses carried out using the Rietveld method on exhausted zeolite. The most evident deformation effects were the lowering of the Fd-3m real symmetry in the parent zeolite to Fd-3 and the remarkable deformations which occurred in the 12-membered ring cage window after sulfadiazine or sulfachloropyridazine adsorption. After sulfamethazine adsorption, zeolite deformation caused a lowering in symmetry up to the monoclinic P2/m space group. The effective and irreversible adsorption of sulfonamides into organophylic Y zeolite makes this cheap and environmentally friendly material a suitable candidate for removing sulfonamides from water. PMID:20133061

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

2010-06-15

36

Prominent redox feature of copper ion exchanged in ZSM-5-type zeolite  

Microsoft Academic Search

The redox features of copper ion exchanged in ZSM-5 were investigated in both evacuation–oxidation–re-evacuation and evacuation–hydration–re-evacuation processes. The XANES and ESR spectra clearly indicated the conversion of Cu(II) ion exchanged in ZSM-5 into Cu(I) with increasing evacuation temperatures. The ability of Cu(I) formed to undergo a complete oxidation with O2 at 673K was certified and succeeding reduction process by heat

Yasushige Kuroda; Ryotaro Kumashiro; Mahiko Nagao

2002-01-01

37

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

38

Preparation and characterization of surfactant-modified hydroxyapatite/zeolite composite and its adsorption behavior toward humic acid and copper(II).  

PubMed

A novel composite material, i.e., surfactant-modified hydroxyapatite/zeolite composite, was used as an adsorbent to remove humic acid (HA) and copper(II) from aqueous solution. Hydroxyapatite/zeolite composite (HZC) and surfactant-modified HZC (SMHZC) were prepared and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscope. The adsorption of HA and copper(II) on SMHZC was investigated. For comparison purposes, HA adsorption onto HZC was also investigated. SMHZC exhibited much higher HA adsorption capacity than HZC. The HA adsorption capacity for SMHZC decreased slightly with increasing pH from 3 to 8 but decreased significantly with increasing pH from 8 to 12. The copper(II) adsorption capacity for SMHZC increased with increasing pH from 3 to 6.5. The adsorption kinetic data of HA and copper(II) on SMHZC obeyed a pseudo-second-order kinetic model. The adsorption of HA and copper(II) on SMHZC took place in three different stages: fast external surface adsorption, gradual adsorption controlled by both film and intra-particle diffusions, and final equilibrium stage. The equilibrium adsorption data of HA on SMHZC better fitted to the Langmuir isotherm model than the Freundlich isotherm model. The equilibrium adsorption data of copper(II) on SMHZC could be described by the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The presence of copper(II) in solution enhanced HA adsorption onto SMHZC. The presence of HA in solution enhanced copper(II) adsorption onto SMHZC. The mechanisms for the adsorption of HA on SMHZC at pH 7 may include electrostatic attraction, organic partitioning, hydrogen bonding, and Lewis acid-base interaction. The mechanisms for the adsorption of copper(II) on SMHZC at pH 6 may include surface complexation, ion exchange, and dissolution-precipitation. The obtained results indicate that SMHZC can be used as an effective adsorbent to simultaneously remove HA and copper(II) from water. PMID:22961484

Zhan, Yanhui; Lin, Jianwei; Li, Jia

2013-04-01

39

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

40

The Modification of Polyamide Tapes by the Conducting Copper Sulfide-Copper Selenide Layers  

Microsoft Academic Search

duration of treatment. The SeS4O6 2- anions diffused into polyamide gradually decompose and the decomposition products - sulfate ions and SO2 - are washed out from a polymer but elemental selenium remains in it. Therefore, the colour of polyamide tapes depending on a degree of SeS4O6 2- ions decomposition changes from colourless to yellow, brown or red. The copper sulfide

Vitalijus JANICKIS; Remigijus IVANAUSKAS

41

Surface Modification of a Photo-Definable Epoxy Resin with Polydopamine to Improve Adhesion with Electroless Deposited Copper  

Microsoft Academic Search

This paper describes the influence of polydopamine surface modifications on the adhesion strength of electroless deposited copper on roughened epoxy resin substrates. The surfaces are characterized with XPS and ToF-S-SIMS. Next, a thorough investigation of the copper–epoxy interface is performed using SEM. Both the polydopamine modification and the variation of the electroless plating bath temperature lead to new insights into

David Schaubroeck; Emilie Van Den Eeckhout; Johan De Baets; Peter Dubruel; Luc Van Vaeck; André Van Calster

2012-01-01

42

Selective deposition of conductive copper films on glass surfaces using femtosecond laser surface modification and electroless plating  

Microsoft Academic Search

In this paper, selective deposition of conductive copper films on glass surfaces is demonstrated with the assistance of femtosecond laser surface modification followed by electroless plating. Irradiation of femtosecond laser makes it possible to selectively deposit copper films in the irradiated area on glass surfaces coated with silver nitrate films. The influence of the laser direct writing parameters and the

Jian Xu; Yang Liao; Huidan Zeng; Zenghui Zhou; Haiyi Sun; Juan Song; Xinshun Wang; Ya Cheng; Zhizhan Xu; Koji Sugioka; Katsumi Midorikawa

2008-01-01

43

Host (nanocavity of zeolite-Y)–guest (tetraaza[14]annulene copper(II) complexes) nanocomposite materials: Synthesis, characterization and liquid phase oxidation of benzyl alcohol  

Microsoft Academic Search

Copper(II) complexes with tetraaza[14]annulene ligands “5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradecine [Cu(Me4R2Bzo[14]tetraeneN4)] (R=H, CH3, Cl and NO2)” have been prepared from the one-pot template condensation reaction of substituted-1,2-phenylenediamine (4-methyl-; 4-chloro-; 4-nitro-1,2-phenylenediamine) with 2,4-pentanedione in the presence of copper(II) ion within the nanocavity pores of zeolite-Y “[Cu(Me4R2Bzo[14]tetraeneN4)]–NaY”. The new materials were characterized by several techniques: chemical analysis and spectroscopic methods (FT-IR, UV\\/vis, XRD, BET and DRS).

Masoud Salavati-Niasari

2006-01-01

44

Immobilization of a copper-Schiff base complex in a Y-zeolite matrix: Preparation, chromogenic behavior and catalytic oxidation  

Microsoft Academic Search

A new zeolite-immobilized hybrid catalyst Cu(MeO-salen)-NaY has been prepared by encapsulating [Cu(MeO-salen)(H2O)] (1) [where MeO-salenH2=N,N?-(ethylene)-bis-(3-methoxysalicylaldimine)] in a NaY zeolite matrix. The hybrid material has been characterized by UV–Vis, IR and EPR spectrometry and by X-ray powder diffraction analysis. The pristine complex [Cu(MeO-salen)(H2O)] (1) has also been synthesized and characterized by all the spectrometric methods mentioned above as well as by

Pratap Kumar Saha; Buddhadeb Dutta; Sreyashi Jana; Rajesh Bera; Sandip Saha; Ken-ichi Okamoto; Subratanath Koner

2007-01-01

45

Preparation and characterization of zeolite framework stabilized cuprous oxide nanoparticles  

Microsoft Academic Search

Zeolite framework stabilized copper(I) oxide nanoparticles (4.8±2.6 nm) were prepared for the first time by using a four step procedure: the ion exchange of Cu2+ ions with the extra framework Na+ ions in Zeolite-Y, the reduction of the Cu2+ ions within the cavities of zeolite with sodium borohydride in aqueous solution, the dehydration of Zeolite-Y with the copper(0) nanoclusters, and the

Mehmet Zahmakiran; Saim Özkar

2009-01-01

46

Comparison between copper-mediated and hypochlorite-mediated modifications of human low density lipoproteins evaluated by protein carbonyl formation  

Microsoft Academic Search

The purpose of this study was to evaluate the mech- anisms of apolipoprotein B (apoB) modification during oxi- dation of human low density lipoproteins (LDL) mediated ei- ther by copper or by hypochlorite (HOCl). The kinetics of protein carbonyl formation, the relationship of apoB carbonyl formation to lipid peroxidation, and the loss of apoB lysine residues were determined. During copper-mediated

Liang-Jun Yan; John K. Lodge; Maret G. Traber; Seiichi Matsugo; Lester Packer

47

Oxidative decomposition of benzene and its methyl derivatives catalyzed by copper and palladium ion-exchanged Y-type zeolites  

Microsoft Academic Search

The catalytic deep oxidation of benzene, toluene and xylene over NaY, CuY, PdHY and PdY zeolites has been investigated in the temperature range 493–623K. PdY is the most active catalyst even at low Pd content while CuY achieves distinct catalytic activity only at higher Cu content. Reductive pretreatment increases the conversion for PdY but decreases the activity of CuY. The

Lutz Becker; Horst Förster

1998-01-01

48

Effects of the surface modification by remote hydrogen plasma on adhesion in the electroless copper \\/ tetrafluoroethylene - hexafluoropropylene copolymer (FEP) system  

Microsoft Academic Search

FEP sheets were modified with a remote hydrogen plasma and the effects of the modification on the adhesion between copper metal and FEP sheets were investigated. The remote hydrogen plasma treatment is able to make FEP surfaces hydrophilic. In the remote hydrogen plasma treatment process, both defluorination and oxidation occur on the FEP surface. The oxidation reactions on the FEP

N. Inagaki; S. Tasaka; Y. W. Park

1998-01-01

49

Tailored zeolites for the removal of metal oxyanions: overcoming intrinsic limitations of zeolites.  

PubMed

This review aims to present a global view of the efforts conducted to convert zeolites into efficient supports for the removal of heavy metal oxyanions. Despite lacking affinity for these species, due to inherent charge repulsion between zeolite framework and anionic species, zeolites have still received considerable attention from the scientific community, since their versatility allowed tailoring them to answer specific requirements. Different processes for the removal and recovery of toxic metals based on zeolites have been presented. These processes resort to modification of the zeolite surface to allow direct adsorption of oxyanions, or by combination with reducing agents for oxyanions that allow ion-exchange with the converted species by the zeolite itself. In order to testify zeolite versatility, as well as covering the wide array of physicochemical constraints that oxyanions offer, chromium and arsenic oxyanions were selected as model compounds for a review of treatment/remediation strategies, based on zeolite modification. PMID:24794984

Figueiredo, Hugo; Quintelas, Cristina

2014-06-15

50

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

51

Thermal behavior of natural zeolites  

SciTech Connect

Thermal behavior of natural zeolites impacts their application and identification and varies significantly from zeolite to zeolite. Zeolites evolve H{sub 2}0 upon heating, but recent data show that distinct ``types`` of water (e.g., loosely bound or tightly bound zeolitic water) do not exist. Rather water is bound primarily to extra-framework cations with a continuum of energies, giving rise to pseudocontinuous loss of water accompanied by a dynamic interaction between remaining H{sub 2}0 molecules and extra-framework cations. These interactions in the channels of zeolites give rise to dehydration dependent on the extra-framework cation, in addition to temperature and water vapor pressure. The dehydration reaction and the extra-framework cation also affect the thermal expansion/contraction. Most zeolites undergo dehydration-induced contractions that may be anisotropic, although minor thermal expansion can be seen with some zeolites. Such contractions can be partially or completely irreversible if they involve modifications of the tetrahedral framework and/or if rehydration is sluggish. Thermally induced structural modifications are also driven initially by dehydration and the concomitant contraction and migration of extra-framework cations. Contraction is accommodated by rotations of structural units and tetrahedral cation-oxygen linkages may break. Thermal reactions that involve breaking of tetrahedral cation-oxygen bonds markedly irreversible and may be kinetically limited, producing large differences between short- and long-term heating.

Bish, D.L.

1993-09-01

52

COPPER  

EPA Science Inventory

The report is a review of current knowledge of the distribution of copper in the environment and living things. Metabolism and the effects of copper in the biosphere are also considered. Copper compounds are common and widely distributed in nature. They are also extensively mined...

53

Modification of the Preston equation for the chemical–mechanical polishing of copper  

Microsoft Academic Search

Chemical-mechanical polishing (CMP) of copper was conducted in two acidic (pH 1.3 and 3.8) slurries and one alkaline pH (10?12) slurry with alumina particles as the abrasives. In acidic media with 0.1 M Fe(NO3)3 as a copper etchant and [1]H-benzotriazole (BTA) as an inhibitor, copper polish rate increases linearly with solids concentration in the polishing slurry. The polish rate increased

Q. Luo; S. Ramarajan; S. V. Babu

1998-01-01

54

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

55

Inactivation of high and low pathogenic avian influenza virus H5 subtypes by copper ions incorporated in zeolite-textile materials.  

PubMed

The effect of cotton textiles containing Cu(2+) held by zeolites (CuZeo-textile) on the inactivation of H5 subtype viruses was examined. Allantoic fluid (AF) containing a virus (AF virus) (0.1 ml) was applied to the textile (3×3-cm), and incubated for a specific period at ambient temperature. After each incubation, 0.9 ml of culture medium was added followed by squeezing to recover the virus into the medium. The recovered virus was titrated using Madin-Darby canine kidney (MDCK) cells or 10-day-old embryonated chicken eggs. The highly pathogenic H5N1 and the low pathogenic H5N3 viruses were inactivated on the CuZeo-textile, even after short incubation. The titer of A/chicken/Yamaguchi/7/04 (H5N1) in MDCK cells and in eggs declined by >5.0 log(10) and 5.0 log(10), respectively, in 30 s. The titer of A/whooper swan/Hokkaido/1/08 (H5N1) in MDCK cells declined by 2.3 and 3.5 in 1 and 5 min, respectively. When A/whistling swan/Shimane/499/83 (H5N3) was treated on the CuZeo-textile for 10 min, the titer declined by >5.0 log(10) in MDCK cells and by >3.5 log(10) in eggs. In contrast, no decrease in the titers was observed on cotton textiles containing zeolites alone (Zeo-textile). Neither cytopathic effects nor NP antigens were detected in MDCK cells inoculated with the H5N1 virus treated on the CuZeo-textile. The viral genes (H5, N1, M, and NP) were amplified from the virus treated on the CuZeo-textile by RT-PCR. The hemagglutinating activity of the CuZeo-textile treated virus was unaffected, indicating that virus-receptor interactions were maintained. Electron microscopic analysis revealed a small number of particles with morphological abnormalities in the H5N3 virus samples recovered immediately from the CuZeo-textile, while no particles were detectable in the 10-min treated sample, suggesting the rapid destruction of virions by the Cu(2+) in the CuZeo-textile. The loss of infectivity of H5 viruses could, therefore, be due to the destruction of virions by Cu(2+). Interestingly, CuCl(2) treatment (500 and 5000 ?M) did not have an antiviral effect on the AF viruses (H5N1 and H5N3) even after 48 h of incubation, although the titer of the purified H5N3 virus treated with CuCl(2) declined greatly. The antiviral effect was inhibited by adding the AF to the purified H5N3 virus prior to the CuCl(2) treatment. The known antibacterial/antifungal activities of copper suggest that the CuZeo-textile can be applied at a high level of hygiene in both animals and humans. PMID:22179064

Imai, Kunitoshi; Ogawa, Haruko; Bui, Vuong Nghia; Inoue, Hiroshi; Fukuda, Jiro; Ohba, Masayoshi; Yamamoto, Yu; Nakamura, Kikuyasu

2012-02-01

56

Simultaneous SO{sub 2}/NO{sub x} abatement using zeolite-supported copper. Progress report, April 1--June 30, 1995  

SciTech Connect

Several catalysts for NO decomposition have been reported in the literature to include the following: Cu/ZSM-5; Cu/Zeolite-Y; Cu/mordenite; Cu/{beta} zeolite; Cu/alumina; and Cu/silica which have been studied less than Cu/ZSM-5. The catalytic properties for NO conversion are found to be different on these samples with the ZSM-5 supported catalysts showing the highest activity in a dry environment free from sulfur oxides. One of the goals of this study is to have a better fundamental understanding on the different roles of Cu and the support in the catalytic reaction. The authors use stable, cationic metal complexes in non-aqueous solvents as sources of the Cu ions in producing model catalysts for which the fate of the source molecule is known and is controlled during the ion exchange/impregnation. Molecular models of these systems can be used to identify the possible configurations of the metal complexes within the zeolite support. The authors compare the performance of the model catalysts to one prepared by aqueous impregnation of ZSM-5 zeolite. The performance of the dinuclear metal complex on silica is compared to the same complex in ZSM-5 and Y-zeolites.

Mitchell, M.B.; White, M.G.

1995-12-31

57

Plasma surface modification of polyimide for improving adhesion to electroless copper coatings  

Microsoft Academic Search

The influences of oxygen plasma treatment of polyimide (PI) films on the adhesion of electroless copper coatings as well as on the chemical composition of the film surface and the PI surface morphology were investigated. The plasma operating parameters were 1800 W forward power with O2 flowing at a rate of 300 cm\\/min at a pressure of 200 mTorr. The

G. Rozovskis; J. Vinkevi?ius; J. Ja?iauskiene

1996-01-01

58

The effects of cold temperature on copper ion exchange by natural zeolite for use in a permeable reactive barrier in Antarctica  

Microsoft Academic Search

Permeable reactive barriers (PRBs) are an in-situ passive treatment technology that removes dissolved contaminants from polluted waters through the subsurface emplacement of reactive materials such as natural zeolite. While significant work has been achieved using PRBs in temperate climates, adaptations to existing PRB technology and reactive material characteristics will be necessary for the successful treatment of heavy metal contaminated waters

A. Z Woinarski; I Snape; G. W Stevens; S. C Stark

2003-01-01

59

Zeolite Characterization.  

National Technical Information Service (NTIS)

The Savannah River Site isolates tritium from its process streams for eventual recycling. This is done by catalyzing the formation of tritiated water (from process streams) and then sorbing that water on a 3A zeolite (molsieve) bed. The tritium is recover...

H. L. Nigg W. D. Jacobs

2007-01-01

60

Zeolite micromembranes.  

PubMed

Free-standing silicalite-1 (Sil-1) zeolite micromembranes have been successfully fabricated onto silicon substrate. Gas permeation test using permanent gases (i.e., helium, hydrogen, argon and nitrogen) and hydrocarbons (i.e., methane and n-butane) indicates that the micromembranes have excellent permeance flux and high permselectivity. PMID:15100781

Chau, Joseph Lik Hang; Leung, Adrian Yat Lai; Yeung, King Lun

2003-05-01

61

Quantifying defects in zeolites and zeolite membranes  

NASA Astrophysics Data System (ADS)

Zeolites are crystalline aluminosilicates that are frequently used as catalysts to transform chemical feedstocks into more useful materials in a size- or shape-selective fashion; they are one of the earliest forms of nanotechnology. Zeolites can also be used, especially in the form of zeolite membranes (layers of zeolite on a support), to separate mixtures based on the size of the molecules. Recent advances have also created the possibility of using zeolites as alkaline catalysts, in addition to their traditional applications as acid catalysts and catalytic supports. Transport and catalysis in zeolites are greatly affected by physical and chemical defects. Such defects can be undesirable (in the case of zeolite membranes), or desirable (in the case of nitrogen-doped alkaline zeolites). Studying zeolites at the relevant length scales requires indirect experimental methods such as vapor adsorption or atomic-scale modeling such as electronic structure calculations. This dissertation explores both experimental and theoretical characterization of zeolites and zeolite membranes. Physical defects, important in membrane permeation, are studied using physical adsorption experiments and models of membrane transport. The results indicate that zeolite membranes can be modeled as a zeolite powder on top of a support---a "supported powder," so to speak---for the purposes of adsorption. Mesoporosity that might be expected based on permeation and confocal microscopy measurements is not observed. Chemical defects---substitutions of nitrogen for oxygen---are studied using quantum mechanical models that predict spectroscopic properties. These models provide a method for simulating the 29Si NMR spectra of nitrogendefected zeolites. They also demonstrate that nitrogen substitutes into the zeolite framework (not just on the surface) under the proper reaction conditions. The results of these studies will be valuable to experimentalists and theorists alike in our efforts to understand the versatile and complicated materials that are zeolites.

Hammond, Karl Daniel

62

Zeolite A imidazolate frameworks  

Microsoft Academic Search

Faujasite (FAU) and zeolite A (LTA) are technologically important porous zeolites (aluminosilicates) because of their extensive use in petroleum cracking and water softening. Introducing organic units and transition metals into the backbone of these types of zeolite allows us to expand their pore structures, enhance their functionality and access new applications. The invention of metal-organic frameworks and zeolitic imidazolate frameworks

Hideki Hayashi; Adrien P. Côté; Hiroyasu Furukawa; Michael O'Keeffe; Omar M. Yaghi

2007-01-01

63

Solar refrigeration utilizing zeolites  

Microsoft Academic Search

Zeolites offer a unique opportunity for a solid-gas adsorption refrigeration system because of their unusual sorption properties, in particular, extremely nonlinear adsorption isotherms. The operating principle of the zeolite system and experimental results are presented. The study demonstrates a zeolite system capable of providing refrigeration and ice production with very good engineering efficiency. This system utilizes natural zeolites as the

D. I. Tchernev

1979-01-01

64

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.

2000-01-01

65

Gas chromatography on zeolites using moist carrier gas  

Microsoft Academic Search

Ion-exchangeable forms of dehydrated zeolites are widely used adsorbents for isolation, concentration and gas chromatographic determination of a variety of air pollutants. The authors thought it of interest to study gas chromatographic properties of molecular sieves using moistened carrier gas, assuming that modification of zeolites by water can markedly influence their properties by changing the selectivity and efficiency of separation.

O. S. Banakh; V. G. Berezkin; I. Ya Golos

1986-01-01

66

Investigation of the possibility of intermediate formation of allyl alcohol in the process of oxidative acetoxylation of propylene on a palladium-copper zeolite catalyst  

SciTech Connect

The formation of allyl acetate in reactions of oxidative acetoxylation of propylene by labeled acetic acid and esterification of labeled acetic acid by allyl alcohol on a Pd, Cu-zeolite catalyst occur with complete conservation of the labeled oxygen of the original labeled acetic acid in the reaction product. The authors propose a reaction scheme for the oxidative acetoxylation of propylene, providing for the formation of allyl alcohol as an intermediate compound, present in a chemisorbed state in the form of a complex with a Pd atom. The gas-phase oxidative acetoxylation of propylene is an industrial method of producing allyl acetate.

Minachev, K.M.; Chizhov, O.S.; Kadentsev, V.I.; Kharlamov, V.V.; Nefedov, O.M.; Rodin, A.N.

1985-12-10

67

Direct patterning of copper on polyimide by site-selective surface modification via a screen-printing process.  

PubMed

We demonstrate a simple route to fabricating copper circuit patterns on the surface of polyimide film. The copper pattern can be obtained in three steps: 1) Formation of partially potassium hydroxide modified pattern via a screen-printing process, 2) formation of macromolecular metal complex with copper, and 3) copper metallization by DMAB reduction. The morphologies of these copper patterns are determined by cross-sectional transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). Furthermore, the growing process of the metallic copper film is investigated. The direct patterning of copper patterns onto polyimide substrates is promising for use in electronics industry as a large-area and low-cost processing technique. PMID:21438111

Su, Wei; Li, Peiyuan; Yao, Libei; Yang, Fang; Liang, Lifang; Chen, Juan

2011-04-18

68

Layered zeolitic materials: an approach to designing versatile functional solids.  

PubMed

Relevant layered zeolites have been considered in this perspective article from the point of view of the synthesis methodologies, materials characterization and catalytic implications, considering the unique physico-chemical characteristics of lamellar materials. The potential of layered zeolitic precursors to generate novel lamellar accessible zeolites through swelling, intercalation, pillarization, delamination and/or exfoliation treatments is studied, showing the chemical, functional and structural versatility exhibited by layered zeolites. Recent approaches based on the assembly of zeolitic nanosheets which act as inorganic structural units through the use of dual structural directing agents, the selective modification of germanosilicates and the direct generation of lamellar hybrid organic-inorganic aluminosilicates are also considered to obtain layered solids with well-defined functionalities. The catalytic applications of the layered zeolites are also highlighted, pointing out the high accessibility and reactivity of active sites present in the lamellar framework. PMID:24457617

Díaz, Urbano; Corma, Avelino

2014-07-21

69

Simultaneous SO{sub 2}/NO{sub x} abatement using zeolite-supported copper. Quarterly progress report, January 1, 1995--March 31, 1995  

SciTech Connect

We have significantly improved on our earlier results with a copper-impregnated alumina, obtaining reproducible results for the impregnation procedure and linear behavior with solution concentration of the precursor. The copper acetylacetonate precursor is adsorbed molecularly onto the alumina surface, with no noticeable decomposition. The adsorbed complex appears to form layers on the alumina surface, similar to results found using the same complex with a silica substrate. The materials start out as light blue powders, and after oxidation are light green. Using infrared spectroscopy, we have examined the in situ adsorption and oxidation of SO{sub 2} on the oxidized sorbent, which is dispersed copper oxide supported on aluminum oxide, and have observed that the initial species formed correspond to aluminum sulfate and aluminum sulfate. The sulfate is formed at temperatures much lower than similar experiments studying SO{sub 2} adsorption on alumina and sodium-doped alumina. As a result of oxidation, the adsorbed sulfur species, which begin as aluminum sulfate and sulfate, are converted to copper sulfate.

Mitchell, M.B.; White, M.G.

1995-12-01

70

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.

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

2011-01-01

71

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

72

The lipoic acid analogue 1,2-diselenolane-3-pentanoic acid protects human low density lipoprotein against oxidative modification mediated by copper ion.  

PubMed

1,2-Diselenolane-3-pentanoic acid, in which the sulfur atoms of alpha-lipoic acid are replaced with selenium, displayed markedly different antioxidant properties when compared to alpha-lipoic acid. 1,2-Diselenolane-3-pentanoic acid was unable to inhibit protein oxidative modification of human low density lipoprotein (LDL) and bovine serum albumin induced by copper ion or hydroxyl radical, whereas alpha-lipoic acid showed significant protection. However, 1,2-diselenolane-3-pentanoic acid was able to inhibit the formation of lipid peroxidation products in LDL after oxidation by copper, while alpha-lipoic acid did not. Hence the diselenium compound exerts its effects in a lipophilic environment whilst lipoic acid exerts its effects in a hydrophilic environment. These differences in antioxidant activities of the two compounds may be explained, at least in part, by their differing partition coefficients. PMID:9398652

Matsugo, S; Yan, L J; Konishi, T; Youn, H D; Lodge, J K; Ulrich, H; Packer, L

1997-11-26

73

ZEOLITES: EFFECTIVE WATER PURIFIERS  

EPA Science Inventory

Zeolites are known for their adsorption, ion exchange and catalytic properties. Various natural zeolites are used as odor and moisture adsorbents and water softeners. Due to their acidic nature, synthetic zeolites are commonly employed as solid acid catalysts in petrochemical ind...

74

Zeolite matrices for pigments  

Microsoft Academic Search

Intracrystalline voids in zeolites and other crystalline molecular sieves are suitable for accommodation and stabilization of certain chromophors. Our method of ultramarine synthesis comprises a generation of the anion radicals S3? from precursors (sodium polysulfides) introduced into zeolites. The color of the resulting ultramarine was modified by introduction of various cations into the parent zeolites. Using of polysulfides combined with

S. Kowalak; M. Wróbel; N. Gol?ebniak; A. Jankowska; B. Turkot

1999-01-01

75

Systems including catalysts in porous zeolite materials within a reactor for use in synthesizing hydrocarbons  

DOEpatents

Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

Rolllins, Harry W. (Idaho Falls, ID); Petkovic, Lucia M. (Idaho Falls, ID); Ginosar, Daniel M. (Idaho Falls, ID)

2012-07-24

76

Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons  

DOEpatents

Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

Rollins, Harry W. (Idaho Falls, ID); Petkovic, Lucia M. (Idaho Falls, ID); Ginosar, Daniel M. (Idaho Falls, ID)

2011-02-01

77

Plasmon-Related Modification of Spectral Kinetic Properties of Copper Phthalocyanine Thin Films in the Presence of Silver Nanoparticles*  

NASA Astrophysics Data System (ADS)

We have studied the relaxation dynamics for hot electrons in hybrid layered nanocomposites based on island films of silver and copper phthalocyanine. Using femtosecond kinetic spectroscopy, we have shown that the fast component of the bleaching relaxation kinetics in the spectral region corresponding to the absorption bands of copper phthalocyanine correlates with the recovery kinetics for surface plasmon resonance absorption of the silver nanoparticles. This suggests that the fast relaxing bleaching recorded in the absorption bands of copper phthalocyanine and its dynamics are not due to a change in the populations of the energy states of copper phthalocyanine but rather to a change in the state of the plasmon nanoparticles, as a result of their excitation by femtosecond pulses and subsequent relaxation.

Buganov, O. V.; Zamkovets, A. D.; Ponyavina, A. N.; Tikhomirov, S. A.

2014-03-01

78

Batch and column studies on heavy metal removal using a local zeolitic tuff  

Microsoft Academic Search

Ion exchange is considered to be one of the most cost effective methods if low cost ion exchangers such as natural zeolites are used in waste water treatment. In this study, a zeolitic tuff rich in clinoptilolite from Gördes Manisa Turkey was examined to evaluate its ion exchange performance for the removal of copper, nickel and cobalt ions from metal

Özge Can; Devrim Balköse; Semra Ülkü

2010-01-01

79

Zeolite membranes from kaolin  

SciTech Connect

Zeolite films are sought as components of molecular sieve membranes. Different routes used to prepare zeolite composite membranes include growing zeolite layers from gels on porous supports, depositing oriented zeolites on supports, and dispersing zeolites in polymeric membranes. In most cases, it is very difficult to control and avoid the formation of cracks and/or pinholes. The approach to membrane synthesis is based on hydrothermally converting films of layered aluminosilicates into zeolite films. The authors have demonstrated this concept by preparing zeolite A membranes on alumina supports from kaolin films. The authors have optimized the process parameters not only for desired bulk properties, but also for preparing thin (ca. 5 {micro}m), continuous zeolite A films. Scanning electron microscopy shows highly intergrown zeolite A crystals over most of the surface area of the membrane, but gas permeation experiments indicate existence of mesoporous defects and/or intercrystalline gaps. It has been demonstrated that the thickness of the final zeolite A membrane can be controlled by limiting the amount of precursor kaolin present in the membrane.

Karle, B.G. [Univ. of New Mexico, Albuquerque, NM (United States). Center for Micro-Engineered Ceramics; Brinker, C.J. [Univ. of New Mexico, Albuquerque, NM (United States). Center for Micro-Engineered Ceramics]|[Sandia National Labs., Albuquerque, NM (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

1996-07-01

80

Advanced NMR characterization of zeolite catalysts. Final technical report  

SciTech Connect

The effort described in this report involved a joint industry-university program between the Signal Research Center, Inc., and the University of Illinois, designed to advance the state of knowledge of zeolite catalyst characterization technology for application to zeolite catalysts useful in coal liquefaction related processes. The program involved the application of new and improved high resolution solid state nuclear magnetic resonance (NRM) techniques to the characterization of zeolite catalysts and other related microporous materials. The NMR experiments were performed in the state-of-the-art NMR laboratory at the University of Illinois. In this report the first comprehensive investigation of /sup 17/O NMR of A and Y zeolites by means of static, MASS and VASS (variable angle sample spinning) NMR techniques is presented. The determination of the /sup 17/O isotropic chemical shifts, nuclear quadrupole coupling constants and electric field gradient tensor asymmetry parameters provides valuable supplementary information on zeolite structure. As an extension of the /sup 17/O NMR investigation of zeolites, results for gallosilicates and for several aluminophosphate materials have also been obtained. The work presented in this study demonstrates the ability of using /sup 17/O NMR to observe chemical changes in the oxygen environment of zeolites. This has important implications for the study of zeolite based catalysts. Chemical modifications of catalysts, such as framework substitutions or ion exchange which are commonly used to modify zeolite catalyst activity can be directly studied for their effect on the oxygen rich surface of the zeolite. It is also possible that this technique could be used to directly probe the interactions between the zeolite surface and reactant molecules. 29 refs., 14 figs., 7 tabs.

Welsh, L.B.; Oldfield, E.

1986-03-01

81

Modification of the Interlayer Surface of Layered Copper(II) Hydroxide Acetate with Benzoate Groups: Submicrometer Fiber Generation  

Microsoft Academic Search

We report on the functionalization of layered copper(II) hydroxide acetate with benzoic acid. The grafting of benzoate groups is characterized by thermogravimetry\\/differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The submicrometer fiber generation of the grafted material is clearly demonstrated through scanning electron microscopy.

R. Marangoni; G. A. Bubniak; M. P. Cantão; M. Abbate; W. H. Schreiner; F. Wypych

2001-01-01

82

Removal of metal cations from water using zeolites  

SciTech Connect

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 ([minus]40, +65 mesh) varied from 0.48 to 0.93 g/ml. Attrition losses ranged from 1 to 18% during an hour-long shake test. The 24 zeolites and an ion-exchange resin were tested for the uptake of Cd, Cu, and Zn. Of the natural zeolites, phillipsite proved to be the most efficient, while the mordenites had the lowest uptakes. Sodium was the most effective exchangeable ion for exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multi-ion wastewater. The metal ions Fe[sup 3+], Cu[sup 2+], and Zn[sup 2+] in the copper mine wastewater were removed to below drinking water standards, but Mn[sup 2+] and Ni[sup 2+] were not. Calcium and NH[sub 4][sup +] interfered with the uptake of heavy metals. Adsorbed heavy metals were eluted from zeolites with a 3% NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.

Zamzow, M.J.; Murphy, J.E. (U.S. Bureau of Mines, Reno, NV (United States))

1992-11-01

83

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

84

Trialkylphosphine-stabilized copper(I) dialkylaluminum(III) ethanedithiolate complexes: single-source precursors and a novel modification of copper aluminum disulfide.  

PubMed

Four types of trialkylphosphine-stabilized copper dialkylaluminum ethanedithiolate complexes with the compositions [(i)Pr3PCuSC2H4SAlR2]2 (R = Me, Et, (i)Pr, (t)Bu, vinyl), [((i)Pr3PCu)3(SC2H4S)2AlR2] (R = Et), [(Me3P)3CuSC2H4SAlR2] (R = Me, Et), and [(Me3P)4Cu][SC2H4SAlR2] (R = Me, Et, (i)Pr) have been synthesized and structurally characterized by X-ray diffraction. The first series features an eight-membered (CuSAlS)2 ring as the core structure. The trimethylphosphine complexes can be distinguished as nonionic and ionic compounds, depending on the amount of trimethylphosphine. In systematic thermogravimetric studies, the complexes were converted into the ternary semiconductor CuAlS2. In this process, a novel wurtzite-type CuAlS2 phase was identified. Binary copper sulfide is observed as a minor side product in thermolysis reactions when volatile trialkylaluminum is released. The thermolysis reactions are completed at temperatures between 330 and 470 °C, depending on the aluminum alkyls. The Cu/Al ratio and phase purity of the thermolysis products were determined by Rietveld analysis of the powder X-ray diffraction patterns and by inductively coupled plasma optical emission spectroscopy measurements. To our knowledge, this is the first study of molecular single-source precursors for CuAlS2. PMID:24450969

Kischel, Marcus; Dornberg, Gregor; Krautscheid, Harald

2014-02-01

85

The effect of gate dielectric modification and film deposition temperature on the field effect mobility of copper (II) phthalocyanine thin-film transistors  

NASA Astrophysics Data System (ADS)

The change of the field effect mobility of copper (II) phthalocyanine (CuPc) ultra-thin films with the change of dielectric surface and deposition temperature has been systematically investigated. CuPc films are prepared on bare and modified SiO2 substrates at different deposition temperatures. The crystalline structure and morphology of the films have been characterized by x-ray diffraction and atomic force microscopy. The observed device parameters show that the dielectric surface modification reduces the off-state mobile charge carrier density and interfacial trap density. Dielectric surfaces with lower or comparable surface energy to that of CuPc are found to produce devices with higher mobility. The dependence of mobility on deposition temperature shows a strong correlation with the behaviour of the dielectric layers at various temperatures and the diffusion of CuPc molecules.

Sinha, Sumona; Wang, C.-H.; Mukherjee, M.; Yang, Y.-W.

2014-06-01

86

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

87

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

88

Cupric ion\\/ascorbate\\/hydrogen peroxide-induced DNA damage: DNA-bound copper ion primarily induces base modifications  

Microsoft Academic Search

The kinetics of frank DNA strand breaks and DNA base modifications produced by Cu(II)\\/ascorbate\\/ H2O2 were simultaneously determined in purified human genomic DNA in vitro. Modified bases were determined by cleavage with Escherichia coli enzymes Nth protein (modified pyrimidines) and Fpg protein (modified purines). Single-stranded lesion frequency before (frank strand breaks) and after (modified bases) Nth or Fpg protein digestion

Regen Drouin; Henry Rodriguez; Shu-Wei Gao; Zewdu Gebreyes; Timothy R. O'Connor; Gerald P. Holmquist; Steven A. Akman

1996-01-01

89

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

90

Effect of surface stresses and morphology modification on cupric oxide nanowire growth in the thermal oxidation of copper  

NASA Astrophysics Data System (ADS)

Exerting in-plane tensile surface stress or modifying the morphology of the metal surface by forcibly propelling a stream of abrasive material into the surface (sandblasting) enhances nanowire growth by increasing the density of nanowires in the case of tensile stress, and increasing the density and length of nanowires in the case of sandblasting. This improved nanowire growth is attributed to the decreased size of the oxide grains and as a result, the increased number of grain boundaries in the underlying oxide layers, thus resulting in a facilitated outward diffusion of Cu ions for enhanced nanowire growth. These two very simple methods offer easy and inexpensive ways to generate dense, ultra-long CuO nanowires with larger aspect ratios, as well as shed more light on the growth mechanism of nanowires in the thermal oxidation of copper, which has been greatly debated thus far.

Mema, Rediola

91

Modification and Catalytic Application of Zeolite Beta.  

National Technical Information Service (NTIS)

The Dutch Institute for Catalysis Research (NIOK) subsidises the catalysis research efforts conducted at national universities and gives impetus to the development of more environmentally benign and more efficient chemical production processes. The resear...

P. Kunkeler

1998-01-01

92

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

93

Paracetamol inhibits copper ion-induced, azo compound-initiated, and mononuclear cell-mediated oxidative modification of LDL.  

PubMed

The effects of paracetamol and sodium salicylate on the susceptibility of LDL to oxidative modification were studied. LDL was subjected to Cu(2+)-, azo compound-, or peripheral blood mononuclear cell-initiated oxidation in the absence and presence of paracetamol and salicylate. Paracetamol (100 mumol/L; 25 micrograms LDL/mL) reduced the rate of formation of conjugated dienes and the amount of conjugated dienes formed during Cu(2+)-induced oxidation by 67% and 58%, respectively. Paracetamol (400 mumol/L; 100 micrograms LDL/mL) reduced the generation of lipid peroxides during Cu(2+)-induced oxidation by 43% (P < .05), the relative electrophoretic mobility in agarose gels by 16% (P < .05), and the amount of oxidized LDL taken up by J774 macrophages by 22% (P < .05). Paracetamol (100 mumol/L; 100 micrograms LDL/mL) reduced the 2,2'-azobis-(2-amidinopropane hydrochloride)-initiated lipid peroxidation by 70% (P < .05) and the relative electrophoretic mobility by 34% (P < .05). Paracetamol (100 mumol/L; 100 micrograms LDL/mL) reduced the amount of lipid peroxides generated in LDL during mononuclear cell-mediated oxidation by 69% (P < .01) and the relative electrophoretic mobility by 38% (P < .01). In comparison, 10 mumol/L alpha-tocopherol reduced the amount of lipid peroxides formed during cellular LDL oxidation and the relative electrophoretic mobility by 52% and 65%, respectively (P < .05). In the absence of paracetamol, SOD and catalase inhibited the modification of LDL (P < .05), suggesting that superoxide anions and hydrogen peroxide might be involved in the cell-mediated modification pathway. In the presence of paracetamol, SOD showed no additional inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7670947

Nenseter, M S; Halvorsen, B; Rosvold, O; Rustan, A C; Drevon, C A

1995-09-01

94

Zeolites in Soil Environments.  

National Technical Information Service (NTIS)

Over the past 25 years, natural zeolites have been examined for a variety of agricultural and environmental applications because of their unique cation-exchange, adsorption, and molecular sieving properties and their abundance in near-surface, sedimentary...

D. W. Ming J. L. Boettinger

2001-01-01

95

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

96

ZEOLITE CHARACTERIZATION TESTING  

SciTech Connect

The Savannah River Site isolates tritium from its process streams for eventual recycling. This is done by catalyzing the formation of tritiated water (from process streams) and then sorbing that water on a 3A zeolite (molsieve) bed. The tritium is recovered by regenerating the saturated bed into a Mg-based water cracking unit. The process described has been in use for about 15 years. Recently chloride stress corrosion cracking (SCC) was noted in the system piping. This has resulted in the need to replace the corroded piping and associated molecular sieve beds. The source of chlorine has been debated and one possible source is the zeolite itself. Since new materials are being purchased for recently fabricated beds, a more comprehensive analysis protocol for characterizing zeolite has been developed. Tests on archived samples indicate the potential for mobile chloride species to be generated in the zeolite beds.

Jacobs, W; Herbert Nigg, H

2007-09-13

97

Properties of Natural Zeolites.  

National Technical Information Service (NTIS)

Samples of the naturally occuring zeolites phillipsote, clinoptilolite, erionite, and chabazite have been surveyed for their gas adsorption, ion exchange, and other characteristics. Chabazite and erionite, which are generally more stable, also have higher...

R. A. Munson

1973-01-01

98

Preparation of a clinoptilolite-type korean natural zeolite  

Microsoft Academic Search

A clinoptilolite-type natural zeolite was pretreated by HC1, NaOH, and NaCl solutions to improve the ion-exchange capacities\\u000a for heavy metal ions such as copper, lead, cadmium, and cesium. The pretreated natural zeolite was experimentally investigated\\u000a based on chemical analyses, X-ray diffraction, and BET experiments etc. From experimental data, it was shown that the pretreatment\\u000a with NaCl gave the best ion-exchange

Dae Haeng Lee; Seung Jai Kim; Hee Moon

1999-01-01

99

Adsorption equilibrium of heavy metals on natural zeolites  

Microsoft Academic Search

Prior to equilibrium experiments, a clinoptilolite-type Korean natural zeolite was pretreated with HCl, NaOH, and NaCl to\\u000a improve the ion-exchange capacity for heavy metals. Singleand multi-species equilibrium data of heavy metals such as copper,\\u000a cadmium, cesium, and lead on treated and untreated natural zeolites were measured experimentally. For single-species equilibrium\\u000a data, one of the conventional adsorption isotherms, the Sips equation,

Dae Haeng Lee; Hee Moon

2001-01-01

100

Regenerative Cu/La zeolite supported desulfurizing sorbents  

NASA Technical Reports Server (NTRS)

Efficient, regenerable sorbents for removal of H2S from fluid hydrocarbons such as diesel fuel at moderate condition comprise a porous, high surface area aluminosilicate support, suitably a synthetic zeolite, and most preferably a zeolite having a free lattice opening of at least 6 Angstroms containing from 0.1 to 0.5 moles of copper ions, lanthanum ions or their mixtures. The sorbent removes sulfur from the hydrocarbon fuel in high efficiency and can be repetitively regenerated without loss of activity.

Voecks, Gerald E. (inventor); Sharma, Pramod K. (inventor)

1991-01-01

101

Zeolite A imidazolate frameworks  

NASA Astrophysics Data System (ADS)

Faujasite (FAU) and zeolite A (LTA) are technologically important porous zeolites (aluminosilicates) because of their extensive use in petroleum cracking and water softening. Introducing organic units and transition metals into the backbone of these types of zeolite allows us to expand their pore structures, enhance their functionality and access new applications. The invention of metal-organic frameworks and zeolitic imidazolate frameworks (ZIFs) has provided materials based on simple zeolite structures where only one type of cage is present. However, so far, no metal-organic analogues based on FAU or LTA topologies exist owing to the difficulty imposed by the presence of two types of large cage (super- and ?-cages for FAU, ?- and ?-cages for LTA). Here, we have identified a strategy to produce an LTA imidazolate framework in which both the link geometry and link-link interactions play a decisive structure-directing role. We describe the synthesis and crystal structures of three porous ZIFs that are expanded analogues of zeolite A; their cage walls are functionalized, and their metal ions can be changed without changing the underlying LTA topology. Hydrogen, methane, carbon dioxide and argon gas adsorption isotherms are reported and the selectivity of this material for carbon dioxide over methane is demonstrated.

Hayashi, Hideki; Côté, Adrien P.; Furukawa, Hiroyasu; O'Keeffe, Michael; Yaghi, Omar M.

2007-07-01

102

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.

2014-01-01

103

Hydraulic conductivity of compacted zeolites.  

PubMed

Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (?(dmax)) of fine zeolite was greater than that of granular zeolites. The ?(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low ?(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study. PMID:23460541

Oren, A Hakan; Ozdamar, Tu?çe

2013-06-01

104

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

105

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

106

Determination of copper binding in Pseudomonas putida CZ1 by chemical modifications and X-ray absorption spectroscopy.  

PubMed

Previously performed studies have shown that Pseudomonas putida CZ1 biomass can bind an appreciable amount of Cu(II) and Zn(II) ions from aqueous solutions. The mechanisms of Cu- and Zn-binding by P. putida CZ1 were ascertained by chemical modifications of the biomass followed by Fourier transform infrared and X-ray absorption spectroscopic analyses of the living or nonliving cells. A dramatic decrease in Cu(II)- and Zn(II)-binding resulted after acidic methanol esterification of the nonliving cells, indicating that carboxyl functional groups play an important role in the binding of metal to the biomaterial. X-ray absorption spectroscopy was used to determine the speciation of Cu ions bound by living and nonliving cells, as well as to elucidate which functional groups were involved in binding of the Cu ions. The X-ray absorption near-edge structure spectra analysis showed that the majority of the Cu was bound in both samples as Cu(II). The fitting results of Cu K-edge extended X-ray absorption fine structure spectra showed that N/O ligands dominated in living and nonliving cells. Therefore, by combining different techniques, our results indicate that carboxyl functional groups are the major ligands responsible for the metal binding in P. putida CZ1. PMID:17021877

Chen, XinCai; Shi, JiYan; Chen, YingXu; Xu, XiangHua; Chen, LiTao; Wang, Hui; Hu, TianDou

2007-03-01

107

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

108

Catalytic combustion of propane and natural gas over Cu and Pd modified ZSM zeolite catalysts  

Microsoft Academic Search

Copper-exchanged ZSM-5, ZSM-11 and ZSM-48 as well as Pd-ZSM-5 zeolite catalysts were prepared and tested for their light-off and conversion behaviour in complete oxidation of propane and natural gas. Metal modified ZSM zeolite catalysts were found to be superior to the Pd and Cu\\/alumina catalysts prepared for comparison. Cu-ZSM-5 (Cu, 1.3 wt.-%) appeared to be the most active of the

A. Kalantar Neyestanaki; N. Kumar; L.-E. Lindfors

1995-01-01

109

Advances in nanosized zeolites.  

PubMed

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. PMID:23803972

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

2013-08-01

110

Adsorption of organophosphates into microporous and mesoporous NaX zeolites and subsequent chemistry.  

PubMed

Due to the neurotoxicity of organophosphate (OP) pesticides and nerve agents synthesized as military or terror agents, their safe destruction and disposal is of considerable current importance. A representative OP, trimethyl phosphate (TMP), was adsorbed onto NaX zeolite, two mesoporous modifications, and a low-silica X zeolite. The nucleophilic chemical reactions of TMP with the zeolites were investigated by solid-state 13C and 31P nuclear magnetic resonance (NMR) and the solvent extracts by 1H, 13C, and 31P NMR. Nucleophilic substitution and subsequent hydrolysis reaction schemes are proposed. All of the zeolites have similar TMP decomposition yields, supporting the hypothesis that slow or incomplete diffusion of TMP in the microporous zeolite regions limits TMP decomposition. PMID:21361286

Meng, Qingguo; Doetschman, David C; Rizos, Apostolos K; Lee, Min-Hong; Schulte, Jürgen T; Spyros, Apostolos; Kanyi, Charles W

2011-04-01

111

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

112

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

113

'Water Splitting' by Titanium Exchanged Zeolite A.  

National Technical Information Service (NTIS)

Visually detectable and chromatographically and mass spectrally identified hydrogen gas evolves from titanium (III) exchanged zeolite A immersed in water and illuminated with visible light. Titanium(III) exchanged zeolite X and zeolite Y do not produce th...

S. M. Kuznicki E. M. Eyring

1978-01-01

114

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

115

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

116

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

117

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

118

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

119

Spectroscopy and redox chemistry of copper in mordenite.  

PubMed

Copper-containing zeolites, such as mordenite (MOR), have recently gained increased attention as a consequence of their catalytic potential. While the preferred copper loadings in these catalytic studies are generally high, the literature lacks appropriate spectroscopic and structural information on such Cu-rich zeolite samples. Higher copper loadings increase the complexity of the copper identity and their location in the zeolite host, but they also provide the opportunity to create novel Cu sites, which are perhaps energetically less favorable, but possibly more reactive and more suitable for catalysis. In order to address the different role of each Cu site in catalysis, we here report a combined electron paramagnetic resonance (EPR), UV/Vis-NIR and temperature-programmed reduction (TPR) study on highly copper-loaded MOR. Highly resolved diffuse reflectance (DR) spectra of the CuMOR samples were obtained due to the increased copper loading, allowing the differentiation of two isolated mononuclear Cu(2+) sites and the unambiguous correlation with extensively reported features in the EPR spectrum. Ligand field theory is applied together with earlier suggested theoretical calculations to determine their coordination chemistry and location within the zeolite matrix, and the theoretical analysis further allowed us to define factors governing their redox behavior. In addition to monomeric species, an EPR-silent, possibly dimeric, copper site is present in accordance with its charge transfer absorption feature at 22200 cm(-1), and quantified with TPR. Its full description and true location in MOR is currently being investigated. PMID:24399800

Vanelderen, Pieter; Vancauwenbergh, Julie; Tsai, Ming-Li; Hadt, Ryan G; Solomon, Edward I; Schoonheydt, Robert A; Sels, Bert F

2014-01-13

120

Porous Zeolite: A Potential Ecomaterial.  

National Technical Information Service (NTIS)

A new method of wastewater treatment of fertilizer plant by natural zeolite was set up. In this paper the natural zeolite is pretreated in high temperature to increase the capability of removing NH4+ in wastewater. The capability can be increased more tha...

D. Z. Wang Y. Jiang Z. Chen R. Fang

1994-01-01

121

Electrorheological characterization of zeolite suspensions  

Microsoft Academic Search

The rheological properties of the electrorheological (ER) fluids prepared from commercial zeolites 3A, 5A and 13X suspended in silicone oil were investigated through steady shear and oscillatory shear experiments. Dielectric spectra of the fluids were also measured to examine their possible correlation with the flow behavior of the ER fluids. Among the zeolite ER fluids investigated, the ER fluid using

M. S. Cho; H. J. Choi; I.-J. Chin; W.-S. Ahn

1999-01-01

122

Parameters influencing zeolite incorporation in PDMS membranes  

Microsoft Academic Search

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

Ivo F. J. Vankelecom; Else Scheppers; Robin Heus; Jan B. Uytterhoeven

1994-01-01

123

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.

124

Catalytic activity of copper and palladium based catalysts for toluene total oxidation  

Microsoft Academic Search

In this study, catalysts containing 0.5wt.% of palladium or 5wt.% of copper were compared towards toluene total oxidation using FAU Zeolite and ZrO2 supports. A 0.5%Pd\\/NaFAU and 5%Cu\\/ZrO2 were found to be promising catalysts for this reaction. Palladium presented then a better affinity for FAU zeolite and copper oxide had a better affinity for zirconia. The performances of Pd based

H. L. Tidahy; S. Siffert; F. Wyrwalski; J.-F. Lamonier; A. Aboukaïs

2007-01-01

125

Active copper species in 1-butene skeletal isomerization: comparison between copper-modified MCM-41 and beta catalysts  

Microsoft Academic Search

The role of copper was studied in the skeletal isomerization of 1-butene over copper-modified mesoporous MCM-41 molecular sieve and Beta zeolite. The Cu–H-MCM-41 and Cu–H-Beta catalysts were synthesized in our laboratory and characterized by XRD, nitrogen adsorption, X-ray fluorescence, FTIR of adsorbed pyridine and direct current plasma atomic emission spectrometry. The oxidation state of copper after oxidation and reduction in

V. Nieminen; N. Kumar; J. Datka; J. Päivärinta; M. Hotokka; E. Laine; T. Salmi; D. Yu. Murzin

2003-01-01

126

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

127

Oxygen and hydrogen isotope geochemistry of zeolites  

NASA Astrophysics Data System (ADS)

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.

1990-05-01

128

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

129

The adsorption of fatty acids from vegetable oils with zeolites and bleaching clay\\/zeolite blends  

Microsoft Academic Search

The adsorption of model fatty acids (hepatnoic, oleic), using spiked vegetable oils, was studied using different kinds of\\u000a zeolites (A-zeolite, X, Y-zeolites, mordenite), Y-zeolite exchanged with different cations (alkali, alkaline earth, transition\\u000a metal ions), and with bleaching clay\\/zeolite blends. The adsorption process was shown to be governed by the molecular sieving\\u000a properties of the zeolites involved as well as the

D. R. Taylor; C. B. Ungermann; Z. Demidowicz

1984-01-01

130

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

131

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

132

Copper Test  

MedlinePLUS

... copper in my diet? 1. Should everyone's copper metabolism be evaluated? General screening for copper concentrations is ... in Man and Animals, Genetic Defects in Copper Metabolism. J. Nutr . 133: 1527S-1531S [On-line journal ...

133

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

Microsoft Academic Search

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

Jianwen Zhao; Ruhai Tian; Jinfang Zhi

2008-01-01

134

Zeolites in complex nitrogen biofertilizers  

Microsoft Academic Search

A novel technology for producing complex, ecologically safe biofertilizer, combining advantageous properties of both zeolites and nitrogen-fixing microorganisms has been developed. The resulted biofertilizer is a complex of high-activity nitrogen-fixing strain of Azotobacter chroococcum, isolated from the soil in Armenia and the local zeolite modified by the new technology considering the specific features of this microorganism. The new technology for

Anahit Chakhalyan; Gayane Avetisova; Ashot Saghiyan; Leyli Chil-Akopyan; Lusine Melkonyan; Rudolf Gevorkyan; Hakob Sargsyan; Liana Ghazarian

2008-01-01

135

Mesoporous zeolite single crystal catalysts: Diffusion and catalysis in hierarchical zeolites  

Microsoft Academic Search

During the last years, several new routes to produce zeolites with controlled mesoporosity have appeared. Moreover, an improved catalytic performance of the resulting mesoporous zeolites over conventional zeolites has been demonstrated in several reactions. In most cases, the mesoporous zeolites exhibit higher catalytic activity, but in some cases also improved selectivity and longer catalyst lifetime has been reported. The beneficial

Claus Hviid Christensen; Kim Johannsen; Eric Törnqvist; Iver Schmidt; Henrik Topsøe; Christina Hviid Christensen

2007-01-01

136

Separation of Cesium and Strontium with Zeolites.  

National Technical Information Service (NTIS)

Basic studies of separation of cesium and strontium were made with specimens of zeolite, including the synthetic zeolites A, X and Y, synthetic mordenite, natural modernite and clinoptilolite. Ammonium chloride, which is considered to be the most suitable...

T. Kanno H. Hashimoto

1976-01-01

137

Zeolite Ammonia Removal from Catfish Pond Waters,  

National Technical Information Service (NTIS)

The research focused on developing a zeolite filtration system which will prevent toxic ammonia build-up in catfish ponds. Zeolites are ion exchangers and some natural species are capable of selectively removing ammonia from various types of water systems...

W. R. Reynolds C. W. Williford

1987-01-01

138

Mining Environmental Target Investigation: Natural Zeolites.  

National Technical Information Service (NTIS)

Information on the mining and processing of zeolites is reviewed. Composition, structure, and varieties of zeolite, including erionite (12510428), mordenite (12043742), natrolite (1318952), ferrierite (12173307), and phillipsite (12174184) are presented. ...

A. Albers

1981-01-01

139

Effect of chemical modification of histidines on the copper-induced oligomerization of jack bean urease (EC 3.5.1.5)  

Microsoft Academic Search

Aggregation of jack bean urease (JBU) is associated with alterations of its biological properties, notably the ureolytic and entomotoxic activities. We investigated the influence of metals on protein oligomerization and biological properties. Besides protein aggregation, Cu2+ induces inhibition of both ureolytic and insecticidal activities of JBU. Chemical modification of histidine residues in JBU with diethylpyrocarbonate (DEPC) decreases its affinity for

Cristian Follmer; Célia R. Carlini

2005-01-01

140

Mechanism of Microwave Heating of Zeolite A  

Microsoft Academic Search

The mechanism of microwave heating of A zeolite was studied by comparing the heating properties, cation distributions and dielectric properties of 3A, 4A and 5A zeolites. It was easy to heat hydrated 4A zeolite to a glowing (melting) temperature by microwave (2.45 GHz) radiation from room temperature but was difficult to heat the same zeolite with little hydration. When 4A

Tatsuo Ohgushi; Sridhar Komarneni; Amar S. Bhalla

2001-01-01

141

Isomerization of alkenes during drying over zeolites  

Microsoft Academic Search

We observed that zeolite 5A, a zeolite commonly used for drying, isomerized 1-butene and 1-hexene at room temperature. The activity for 1-butene isomerization on 3A, 4A, 5A and 13X zeolites at temperatures of 300 to 565 K is reported.

David T. Lynch; Sieghard E. Wanke

1994-01-01

142

Chapter 17 Hydrocarbon processing with zeolites  

Microsoft Academic Search

This chapter on hydrocarbon processing with zeolites covers both existing and new catalytic applications of zeolites in oil refining and gas conversion. By way of introduction some structural aspects related to these industries are discussed to provide some background in which to relate the current and future developments. Further, the unique opportunities and limitations of zeolites are discussed in order

I. E. Maxwell; W. H. J. Stork

2001-01-01

143

Influence of Quaternary Ammonium on Sorption of Selected Metal Cations onto Clinoptilolite Zeolite  

Microsoft Academic Search

have permanent negative charges on their surfaces, en- abling them to be modified by cationic surfactants. Such Clay minerals and zeolites have large cation exchange capacities, modification results in a significant increase in total which enable them to be modified by cationic surfactant to enhance their sorption of organic and anionic contaminants. In this study, the organic carbon content of

Zhaohui Li; Daniel Alessi; Lori Allen

2002-01-01

144

Reclaiming silver from silver zeolite  

SciTech Connect

Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

Reimann, G.A.

1991-10-01

145

Reclaiming silver from silver zeolite  

SciTech Connect

Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

Reimann, G.A.

1991-10-01

146

Copper Peroxide.  

National Technical Information Service (NTIS)

The action of hydrogen superoxide on copper salts in alcoholic solutions is studied. The action of hydrogen peroxide on copper hydroxide in alcoholic suspensions, and the action of ethereal hydrogen peroxide on copper hydroxide are discussed. It is conclu...

L. Moser

1988-01-01

147

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

148

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

149

Propylene oligomerization over zeolite catalysts  

SciTech Connect

Zeolites (ZSM-5, boralites, offretite, HY, mordenite, and omega) were bonded with 20 wt% sepiolite into composite catalysts to oligomerize propylene in a fixed-bed, automated pilot unit operating at 30-50 atm under isothermal conditions. Product distributions indicate that oligomer size and structure correlates well with the zeolite pore diameter. In addition to C/sub 6/-C/sub 12/ and higher oligomers, aromatics and branched saturates are formed, indicating the presence of cracking, hydrogen and methyl transfer, isomerization, and dehydrocyclization reactions. Offretite (and HY) minimize C/sub 7/ and C/sub 8/ formation, while the boralite used has shown better oligomerization activity and product yields than either ZSM-5 or the other zeolites tested.

Hsu, J.T.; Galya, L.G.; Occelli, M.L.

1984-08-01

150

Zeolitical materials for microbiological filtrations.  

PubMed

The paper presents some aspects about synthesis of new materials called zeolites which can be utilised as filters with wide application in clinical practice in microbiology and in pharmaceutical industry. The SAPO-5, SAPO-11 and SAPO-34 zeolites were synthesised by hydrothermal crystallisation and using different mixtures. The crystallisation was carried out in teflon-lined stainless steel autoclaves at 180-195 degrees C for 1-2 days, under autogenous pressure. Filtering properties of these materials are different because their pore diameters are different. PMID:12092241

Ciobanu, O; Ciobanu, G

2001-01-01

151

Observation of muonium in zeolites  

NASA Astrophysics Data System (ADS)

Muonium has been directly detected over a range of temperatures and fields by transverse field ?SR in different zeolites: 3A, 13X, USY, ZSM-5, and S-115 (a high-silica form of ZSM-5), as well as in silica gel. The polarizations determined from data at 75 and 150 G were independent of both field and temperature. The amounts of Mu seen vary from ?20% to 40%, with a large missing fraction seen in every case, which may be partly due to slow Mu formation. There is also a fast Mu relaxation rate seen in all samples. This is the first direct observation of Mu in zeolites.

Arseneau, D. J.; Fleming, D. G.; Fyfe, C. A.; Senba, M.

2003-02-01

152

Liquid-phase benzene oxidation to phenol with molecular oxygen catalyzed by Cu-zeolites  

SciTech Connect

The oxidation of benzene to form phenol using cuprous chloride as a catalyst has been reported by Sasaki and his co-workers, who used reaction system oxygen molecules as the oxidant. Takehira and his co-workers have studied benzene oxidation with molecular oxygen catalyzed by Cu(II) salts in the presence of ascorbic acid. Cu ion-exchanged zeolites have been reported to be useful as catalysts for the gas-phase oxidation of some organic materials, and copper ions in zeolites have been indicated to have redox properties according to physicochemical measurements. Armed with this knowledge, the authors have tried the liquid-phase oxidation of benzene with molecular oxygen under atmospheric pressure at room temperature using Cu ion-exchanged zeolite catalysts in the presence of ascorbic acid as a reducing reagent for Cu ions. The catalytic behavior of the Cu zeolites for the benzene oxidation was compared with that of nonanchored cupric and cuprous chloride catalysts. Also, some Cu catalysts impregnated on some amorphous oxide supports, in addition to the zeolites, were tested as catalysts for benzene oxidation with molecular oxygen. 13 refs., 5 figs., 3 tabs.

Ohtani, Tsuyoshi; Nishiyama, Satoru; Tsuruya, Shigeru [Kobe Univ. (Japan)] [and others] [Kobe Univ. (Japan); and others

1995-08-01

153

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

154

Application of Synthetic Zeolites (molecular Sieves) to Catalysis  

Microsoft Academic Search

CONTENTS I. Introduction 904 II. General information on zeolites, and on some of their physicochemical properties 904 III. Preparation of zeolite catalysts 905 IV. Applications of zeolite catalysts 906 V. Selectivity of zeolite catalysts 911 VI. Operating mechanism of zeolite catalysts 912

Khabib M. Minachev; V. I. Garanin; Ya I. Isakov

1966-01-01

155

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

156

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

157

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...

158

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

159

Spin probes of chemistry in zeolites  

SciTech Connect

Electron spin resonance (EPR) studies in zeolites are reviewed in which radiolysis was used to ionize the zeolite lattice, create reactive intermediates, spin label reaction products and to provide a window onto chemistry and transport of adsorbates and matrix control of chemistry. The review examines reactions of radical cations and the influence of the geometry constraints inside the zeolite, explores how zeolite model systems can be used to learn about energy and charge transfer in solids and illustrates the use of radiolysis and EPR for in situ spectroscopic studies of solid-acid catalysis. The various spin probes created inside the zeolite pores report on properties of the zeolites as well as shed light on radiolytic processes.

Werst, D.W.; Trifunac, A.D.

1997-09-01

160

Surfactant-modified zeolite as a slow release fertilizer for phosphorus.  

PubMed

The feasibility of using surfactant-modified zeolite (SMZ) as a carrier for fertilizer and for slow release of phosphorus (P) was investigated. Zeolite-A was modified by using hexadecyltrimethylammonium bromide, a cationic surfactant, to modify its surface to increase its capacity to retain anion, namely, phosphate (PO4(3-)). SMZ was thoroughly characterized using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy to study the effect of surfactant modification. Zeolite-A and SMZ were then subjected to P loading by treating them with fertilizer (KH2PO4). It was observed that the P loading on SMZ increased by a factor of 4.9 as compared to the unmodified zeolite-A. A comparative study of the release of P from fertilizer-loaded unmodified zeolite-A and SMZ and from solid KH2PO4 was performed using the constant flow percolation reactor. The results show that the P supply from fertilizer-loaded SMZ was available even after 1080 h of continuous percolation, whereas P from KH2PO4 was exhausted within 264 h. The results indicate that SMZ is a good sorbent for PO4(3-), and a slow release of P was achievable. These properties suggest that SMZ has a great potential as the fertilizer carrier for slow release of P. PMID:16787027

Bansiwal, Amit Kumar; Rayalu, Sadhana Suresh; Labhasetwar, Nitin Kumar; Juwarkar, Asha Ashok; Devotta, Sukumar

2006-06-28

161

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

162

Observation of muonium in zeolites  

Microsoft Academic Search

Muonium has been directly detected over a range of temperatures and fields by transverse field muSR in different zeolites: 3A, 13X, USY, ZSM-5, and S-115 (a high-silica form of ZSM-5), as well as in silica gel. The polarizations determined from data at 75 and 150 G were independent of both field and temperature. The amounts of Mu seen vary from

D. J. Arseneau; D. G. Fleming; C. A. Fyfe; M. Senba

2003-01-01

163

Observation of muonium in zeolites  

Microsoft Academic Search

Muonium has been directly detected over a range of temperatures and fields by transverse field ?SR in different zeolites: 3A, 13X, USY, ZSM-5, and S-115 (a high-silica form of ZSM-5), as well as in silica gel. The polarizations determined from data at 75 and 150 G were independent of both field and temperature. The amounts of Mu seen vary from

D. J. Arseneau; D. G. Fleming; C. A. Fyfe; M. Senba

2003-01-01

164

Zeolites Remove Sulfur From Fuels  

NASA Technical Reports Server (NTRS)

Zeolites remove substantial amounts of sulfur compounds from diesel fuel under relatively mild conditions - atmospheric pressure below 300 degrees C. Extracts up to 60 percent of sulfur content of high-sulfur fuel. Applicable to petroleum refineries, natural-gas processors, electric powerplants, and chemical-processing plants. Method simpler and uses considerably lower pressure than current industrial method, hydro-desulfurization. Yields cleaner emissions from combustion of petroleum fuels, and protects catalysts from poisoning by sulfur.

Voecks, Gerald E.; Sharma, Pramod K.

1991-01-01

165

Enhanced reduction of chromate and PCE by pelletized surfactant-modified zeolite/zerovalent iron  

SciTech Connect

The current research focuses on enhanced removal of chromate and perchloroethylene from contaminated water by a combination of a reduction material (represented by zerovalent iron, ZVI) and a sorption material (represented by surfactant-modified zeolite, SMZ). Natural zeolite and ZVI were homogenized and pelletized to maintain favorable hydraulic properties while minimizing material segregation due to bulk density differences. The zeolite/ZVI pellets were modified with the cationic surfactant hexadecyltrimethylammonium bromide to increase contaminant sorption and, thus, the contaminant concentration on the solid surface. Results of chromate sorption/reduction indicate that the chromate sorption capacity of pelletized SMZ/ZVI is at least 1 order of magnitude higher than that of zeolite/ZVI pellets. Compared to SMZ pellets, the chromate removal capacity of SMZ/ZVI pellets in a 24-h period is about 80% higher, due to the combined effects o sorption by SMZ and reduction by ZVI. The chromate and PCE degradation rates with and without surfactant modification were determined separately. The pseudo-first-order reduction constant increased by a factor of 3 for PCE and by a factor of 9 for chromate following surfactant modification. The enhanced contaminant reduction capacity of SMZ/ZVI pellets may lead to a decrease in the amount of material required to achieve a given level of contaminant removal.

Li, Z.; Jones, H.K.; Bowman, R.S.; Helferich, R.

1999-12-01

166

Catalytic activation of OKO zeolite with intersecting pores of 10- and 12-membered rings using atomic layer deposition of aluminium.  

PubMed

Tetrahedral framework aluminium was introduced in all-silica zeolite -COK-14 using Atomic Layer Deposition (ALD) involving alternating exposure to trimethylaluminium and water vapour. The modification causes permanent conversion of the originally interrupted framework of -COK-14 to a fully connected OKO type framework, and generates catalytic activity in the acid catalysed hydrocarbon conversion reaction. PMID:24667934

Verheyen, E; Pulinthanathu Sree, S; Thomas, K; Dendooven, J; De Prins, M; Vanbutsele, G; Breynaert, E; Gilson, J-P; Kirschhock, C E A; Detavernier, C; Martens, J A

2014-05-01

167

Mixing of zeolite powders and molten salt.  

National Technical Information Service (NTIS)

Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic dis...

C. Pereira V. N. Zyryanov M. A. Lewis J. P. Ackerman

1996-01-01

168

Oxygen and hydrogen isotope geochemistry of zeolites  

Microsoft Academic Search

Zeolites are widespread minerals and occur in a large variety of rock types. More than 40 naturally occurring species have been described. Zeolites are hydrous aluminosilicates which possess unique properties such as reversible dehydration, selective sorption, molecular sieving, ion exchange, and catalysis. While we known a great deal about their occurrence, chemistry, crystal structure, and physical properties, we know relatively

H. R. Karlsson; R. N. Clayton

1990-01-01

169

Chemical interactions in multimetal\\/zeolite catalysts  

Microsoft Academic Search

Mechanistic explanations have been found for the migration of atoms and ions through the zeolite channels leading to specific distribution of ions and the metal clusters. In this report, we summarize the state of understanding attained on a number of topics in the area of mono- and multimetal\\/zeolite systems, to which our recent research has made significant contributions. The following

Sachtler; W. M. H

1992-01-01

170

Fly Ash Zeolites as Sulfur Dioxide Adsorbents  

Microsoft Academic Search

Air protection technologies generate massive amounts of solid wastes, including fly ash (FA). Zeolite synthesis from FA seems to be an effective method for FA utilization. In addition, fly ash zeolites (FAZs) could be used for sulfur dioxide (SO2) adsorption. Since there is a lack of sufficient information about SO2 uptake on FAZs, we investigated this phenomenon in detail. Two

T. T. Suchecki; T. Wa?ek; M. Banasik

171

Metal/zeolite catalysts of methane dehydroaromatization  

NASA Astrophysics Data System (ADS)

Results of studying methane dehydroaromatization over metal/zeolite catalysts have been reviewed. Special attention has focused on molybdenum catalysts based on HZSM-5 zeolites. The effect of catalyst synthesis and reaction conditions on the catalytic properties of the systems has been scrutinized. Information on the mechanism of the process and the nature of active sites has been reported. The bibliography includes 137 references.

Mamonov, N. A.; Fadeeva, E. V.; Grigoriev, D. A.; Mikhailov, M. N.; Kustov, Leonid M.; Alkhimov, S. A.

2013-06-01

172

[Morphology of pneumoconiosis induced by natural zeolite].  

PubMed

Pneumoconiosis was induced in white rats through intratracheal administration of natural zeolite. It was characterized by intensive phagocytosis of the specks of dust, moderate cytotoxic action on the macrophages, as well as inflammatory processes in the vascular system and alveolar epithelium. Zeolite induced fibrosis did not develop to the extent as in case with quartz induced massive collagen formation. PMID:2165972

Kruglikov, G G; Velichkovski?, B T; Garmash, T I

1990-01-01

173

Ion exchange equilibria in zeolite minerals  

Microsoft Academic Search

Cation exchange equilibria of the most common sedimentary zeolites are reviewed. Selected exchange isotherms and thermodynamic equilibrium constants are reported and interpreted in terms of selectivity of one cation over another. Selectivity sequences of various zeolites are compared with each other in the light of Eisenman's theory and utilized to predict or explain specific practical performances.

C. Colella; Napoli Federico; Piazzale V. Tecchio

1996-01-01

174

Octane-enhancing zeolitic FCC catalysts  

Microsoft Academic Search

While particular aspects of octane- enhancing catalysts and zeolites are often described in detail in different articles and patents, this book provides a comprehensive, unified view of this topic. The author has organized the wealth of disparate data and information from the literature by the frequent use of classifications. For example, high-silica Y zeolites were classified according to their preparation

Scherzer

1990-01-01

175

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...

176

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

177

Energy and materials flows in the copper industry  

SciTech Connect

The copper industry comprises both the primary copper industry, which produces 99.9%-pure copper from copper ore, and the secondary copper industry, which salvages and recycles copper-containing scrap metal to extract pure copper or copper alloys. The United States uses about 2 million tons of copper annually, 60% of it for electrical applications. Demand is expected to increase less than 4% annually for the next 20 years. The primary copper industry is concentrated in the Southwest; Arizona produced 66% of the 1979 total ore output. Primary production uses about 170 x 10/sup 12/ Btu total energy annually (about 100 x 10/sup 6/ Btu/ton pure copper produced from ore). Mining and milling use about 60% of the total consumption, because low-grade ore (0.6% copper) is now being mined. Most copper is extracted by smelting sulfide ores, with concomitant production of sulfur dioxide. Clean air regulations will require smelters to reduce sulfur emissions, necessitating smelting process modifications that could also save 20 x 10/sup 12/ Btu (10 x 10/sup 6/ Btu/ton of copper) in smelting energy. Energy use in secondary copper production averages 20 x 10/sup 6/ Btu/ton of copper. If all copper products were recycled, instead of the 30% now salvaged, the energy conservation potential would be about one-half the total energy consumption of the primary copper industry.

Gaines, L.L.

1980-12-01

178

Copper Coordination in Cu-SSZ-13 and Cu-SSZ-16 Investigated by Variable-Temperature XRD  

SciTech Connect

Nitrogen oxides (NO{sub x}) are a major atmospheric pollutant produced through the combustion of fossil fuels in internal combustion engines. Copper-exchanged zeolites are promising as selective catalytic reduction catalysts for the direct conversion of NO into N{sub 2} and O{sub 2}, and recent reports have shown the enhanced performance of Cu-CHA catalysts over other zeolite frameworks in the NO decomposition of exhaust gas streams. In the present study, Rietveld refinement of variable-temperature XRD synchrotron data obtained for Cu-SSZ-13 and Cu-SSZ-16 is used to investigate the location of copper cations in the zeolite pores and the effect of temperature on these sites and on framework stability. The XRD patterns show that the thermal stability of SSZ-13 is increased significantly when copper is exchanged into the framework compared with the acid form of the zeolite, H-SSZ-13. Cu-SSZ-13 is also more thermally stable than Cu-SSZ-16. From the refined diffraction patterns, the atomic positions of atoms, copper locations and occupancies, and thermal displacement parameters were determined as a function of temperature for both zeolites. Copper is found in the cages coordinated to three oxygen atoms of the six-membered rings.

Fickel, D.; Lobo, R

2010-01-01

179

Evaluation of zeolite-sand mixtures as reactive materials protecting groundwater at waste disposal sites.  

PubMed

To recognize properties of a mixture of Vistula sand (medium sand acc. to USCS) with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite (ZS20, ZS50 and ZS80). Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH4+ (at 100%), K+ (at 93%) and Fe(total) (at an average of 86%) were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand. PMID:24520718

Joanna, Fronczyk; Kazimierz, Garbulewski

2013-09-01

180

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

181

Physicochemical properties and different sequence of metal loading (CuFe) over nanoporous of SUZ-4 zeolite.  

PubMed

Different sequence of Cu and Fe loading over nanoporous SUZ-4 zeolite were prepared by incipient wetness impregnation method. K/SUZ-4 zeolite was prepared with SiO2:Al2O3 molar ratio of 21.2 under hydrothermal process at 150 degrees C, 250 rpm for 1 day using tetraethylammonium hydroxide (TEAOH) as a template. Copper(II) and Iron(III) were loaded in K/SUZ-4 with 2.3 and 5.5 wt.% of Copper(II) and 1.0 and 5.0 wt.% of Iron(III). The physico-chemical characterization of CuFe/SUZ-4 were investigated using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET-N2 adsorption, Scanning electron microscopy (SEM) and chemical element analysis. The results show the several types of sequential loading of Cu and Fe metals did not change the structure and pore size of nanoporous SUZ-4 zeolite. The obtained CuFe/SUZ-4 zeolites has a narrow pore size distribution with approximately 0.06 microm diameter with 0.66 microm length of needle crystal shape. PMID:23763208

Pornrattanapimolchai, Choompoonut; Worathanakul, Patcharin

2013-04-01

182

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

183

Solar cogeneration for copper smelting  

Microsoft Academic Search

Work is reported on designing a system for solar repowering of a cogenerating flash smelting furnace that produces copper and sulfuric acid. Smelter energy requirements are listed and the proposed project is described. Several modifications to existing equipment and additional investment in the plant are listed that are necessary as a result of the solar power system improvement. Expected enhancements

P. Curto; A. Gillespie

1981-01-01

184

Resonance Raman and photophysical studies of transition metal complexes in solution and entrapped in zeolites  

SciTech Connect

We have obtained convincing evidence for localization of the optical electron on a single-ring fragment of a chelated bipyridine-like'' ligand (ie., pyridylpyrazine or 4-Methyl-bipyridine). In addition we have completed studies of Ru(bipyrazine){sub 3}{sup 2+} in aqueous sulfuric acid (0--98% by weight) and find clear evidence for sequential addition of six-protons to the six peripheral nitrogen atoms. Studies of zeolite-entrapped complexes are continuing and a series of homo- and heteroleptic complexes have been prepared and characterized. Finally, the synthesis of zeolite-entrapped metallophthalocyanines has now been developed and the copper and cobalt analogues synthesized. The characterization of these materials is now in progress.

Kincaid, J.R.

1992-03-31

185

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

186

Cracking Activity of Zeolite Y Catalysts Synthesized from a South African Kaolinite.  

National Technical Information Service (NTIS)

Rare earth cation exchanged zeolite Y catalysts, rare earth acidic exchanged zeolite Y catalysts, and ultrastable zeolite Y catalysts with or without exchanged rare earth cations were prepared from ceramic microspheres which contained 24% NaY zeolites. A ...

M. G. Howden

1981-01-01

187

Pulsed laser deposition of zeolitic membranes  

SciTech Connect

The pulsed laser deposition of zeolites to form zeolitic thin films is described. Films were grown using both mordenite and faujasite targets and were deposited on various substrates. The optimal films were obtained when the target and substrate were separated by 5 cm. These films are comprised of small crystallites embedded in an amorphous matrix. Transmission electron microscopy reveals that the amorphous material is largely porous and that the pores appear to be close to the same size as the parent zeolite. Zeolotic thin films are of interest for sensor, gas separation, and catalytic applications.

Peachey, N.M.; Dye, R.C. [Los Alamos National Lab., NM (United States); Ries, P.D. [Dow Chemical Co., Midland, MI (United States)

1995-02-01

188

Role of structural similarity between starting zeolite and product zeolite in the interzeolite conversion process.  

PubMed

GIS- and LTL- (the three capital characters indicate the framework type-code) type zeolites were obtained by organic structure-directing agent free hydrothermal conversion of FAU-type zeolite at 125 degrees C in the presence of NaOH and KOH, respectively. MOR-type zeolite was found coexisting with GIS-type when the hydrothermal conversion with NaOH was carried out at 140 degrees C. There was a common building unit consisting of four-membered ring chain such as d6r, dsc, and dcc (the three characters indicate the composite building unit-code) units present in both the starting zeolite (FAU-type zeolite) and the product zeolites (GIS- and LTL-type zeolites), which was the crucial factor for crystal growth through interzeolite conversion. In the case of severe hydrothermal synthesis conditions such as high temperature, however, the crystallization behavior was similar to that observed in conventional hydrothermal synthesis using amorphous materials because the starting zeolite was excessively decomposed. The hypothesis was confirmed by successful interzeolite conversion of *BEA- to MFI-type zeolite which shared the common composite building unit mor. PMID:23763196

Honda, Koutaro; Itakura, Masaya; Matsuura, Yumiko; Onda, Ayumu; Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji

2013-04-01

189

Characterizing the dealumination of environmentally relevant zeolites using IR, NMR and neutron diffraction techniques  

SciTech Connect

Results of characterization studies monitoring the sequential chemical bond breaking events, local site symmetry, and long range structural modifications of specific zeolites (H-ZSM-5, TS-1) during hydrothermal treatment of these catalyst materials are described. These characterization techniques include infrared spectroscopy of selected probe molecules, magic angle spinning NMR spectroscopy, and powder neutron diffraction. Information regarding selected examples from each of these techniques is presented and the inherent strengths of each is discussed. The experimental insight into the chemical and structural modifications of high surface area microporous catalyst materials as a function of deactivation conditions (hydrothermal conditioning) is highlighted.

Paffett, M.T.; Szanyi, J.; Jacubinas, R.M.; Ott, K.C.; VonDreele, R.; Hughes, C.D.; Earl, W.L.

1997-07-01

190

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

191

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

192

Removal of Copper (II) Ions from Aqueous Solutions using Na?mordenite  

Microsoft Academic Search

The potential to remove copper (II) ions from aqueous solutions using Na?mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin?Radushkevich (D?R) isotherms. The maximum sorption capacity was found to be 10.69 mg\\/g at

Cheng Sun

2007-01-01

193

Factors affecting drug adsorption on beta zeolites.  

PubMed

The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO2/Al2O3 ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X-ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity. PMID:23436460

Pasti, Luisa; Sarti, Elena; Cavazzini, Alberto; Marchetti, Nicola; Dondi, Francesco; Martucci, Annalisa

2013-05-01

194

Mixing of zeolite powders and molten salt  

SciTech Connect

Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic disposal. Both processes require mixing of zeolite powders with molten salt at elevated temperatures (>700 K). Complete occlusion of salt and a uniform distribution of chloride and fission products are desired for incorporation of the powders into the final waste form. The relative effectiveness of the blending process was studied over a series of temperature, time, and composition profiles. The major criteria for determining the effectiveness of the mixing operations were the level and uniformity of residual free salt in the mixtures. High operating temperatures (>775 K) improved salt occlusion. Reducing the chloride levels in the mixture to below 80% of the full salt capacity of the zeolite significantly reduced the free salt level in the final product.

Pereira, C.; Zyryanov, V.N.; Lewis, M.A.; Ackerman, J.P.

1996-05-01

195

Synthesis and characterization of nitrogen substituted zeolites  

NASA Astrophysics Data System (ADS)

The interest in basic solid materials, particularly for basic zeolites has considerably increased in the last two decades because of their potential use in catalysis and separation. Basic zeolites have most often been obtained by ion-exchange or impregnation with alkali metal cations or grafting of organic bases onto zeolite pore walls. Such materials often suffer from instability and/or pore blockage, because none of these approaches places basic sites directly into the zeolite framework. Recently zeolitic materials have been made with some of the bridging oxygen atoms in Si--O--Si and/or Si--O--Al linkages replaced by NH groups, i.e. by substitution of framework oxygen by nitrogen. As a result, the basic strength of the framework increases due to the lower electronegativity of nitrogen with respect to oxygen. In this study, solid base catalysts are obtained by nitrogen substitution of the faujasite type of zeolites under ammonia flow at high temperatures. The efficiency of the reaction is tested by using zeolites with different aluminum contents and extraframework cations and varying the reaction conditions such as ammonia flow rate, reaction temperature and duration. The characterization studies show that high levels of nitrogen substitution can be achieved while maintaining porosity, particularly for NaY and low-aluminum HY zeolites, without a significant loss in the crystallinity. 27Al and 29 Si MAS NMR experiments performed on the nitrogen substituted zeolites show dealumination of the framework and preferential substitution for Si--OH--Al sites at the early stages of the reaction (temperatures at 750--800 °C). No preference is seen for reactions performed at higher temperatures and longer reaction times (e.g., 850 °C and 48 h). X-ray PDF analysis performed on the modified zeolites show that the Si-N distance in the 1st shell is longer than Si-O bond distance and Si-Si/Al bond distance of the Si-O/N-Si/Al linkage decreases, as an indication of a decrease in bond angle. The basicity experiments performed on the zeolites show an increase basicity with increase of the nitrogen content.

Dogan, Fulya

196

A sustainable template for mesoporous zeolite synthesis.  

PubMed

A generalized synthesis of high-quality, mesoporous zeolite (e.g., MFI-type) nanocrystals is presented, based on a biomass-derived, monolithic N-doped carbonaceous template. As an example, ZSM-5 single crystals with desirable large-diameter (12-16 nm) intracrystalline mesopores are synthesized. The platform provides scope to optimize template dimensions and chemistry for the synthesis of a range of micro-/mesoporous crystalline zeolites in a cost-effective and highly flexible manner. PMID:24397534

White, Robin J; Fischer, Anna; Goebel, Caren; Thomas, Arne

2014-02-19

197

Acetylene hydration on different Cd-zeolites  

Microsoft Academic Search

Various Cd-zeolite preparations, containing adsorbed water in controlled amounts, were contacted with acetylene in an IR cell at 0.03 bar. The activity of the zeolites was estimated from the formation rate of adsorbed acetaldehyde at 50 °C detected by FTIR. Cd-derivatives of MOR, MFI, and clinoptilolite were prepared by conventional ion exchange and by a novel method which is based

Gy. Onyestyák; G. Pál-Borbély; D. Kalló

2004-01-01

198

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

199

Zeolites: Structural Properties and Benchmarks of Feasibility  

NASA Astrophysics Data System (ADS)

Zeolites are a class of microporous materials that are immensely useful as molecular sieves and catalysts. While there exist millions of hypothetical zeolite topologies, only 206 have been recognized to exist in nature, and the question remains: What distinguishes known zeolite topologies from their hypothetical counterparts? It has been found that all 206 of the known zeolites can be represented as networks of rigid perfect tetrahedra that hinge freely at the connected corners. The range of configurations over which the corresponding geometric constraints can be met has been termed the "flexibility window". Only a small percentage of hypothetical types exhibit a flexibility window, and it is thus proposed that this simple geometric property, the existence of a flexibility window, provides a reliable benchmark for distinguishing potentially realizable hypothetical structures from their infeasible counterparts. As a first approximation of the behavior of real zeolite materials, the flexibility window provides additional useful insights into structure and composition. In this thesis, various methods for locating and exploring the flexibility window are discussed. Also examined is the assumption that the tetrahedral corners are force-free. This is a reasonable approximation in silicates for Si-O-Si angles above ˜135°. However, the approximation is poor for germanates, where Ge-O-Ge angles are constrained to the range ˜120°-145°. Lastly, a class of interesting low-density hypothetical zeolites is evaluated based on the feasibility criteria introduced.

Dawson, Colby

200

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

201

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

202

Zeolite membranes for gas separations  

SciTech Connect

Silicalite-1, a pure silica zeolite, was deposited on a tubular, asymmetric, {gamma}-alumina support. Single gas permeation experiments with N{sub 2}, CH{sub 4}, and CO{sub 2} were carried out on the membrane. Separation experiments for N{sub 2}/CH{sub 4} mixtures were also conducted. Single-gas permeation of H{sub 2} and separation of H{sub 2}/SF{sub 6} mixture were also carried out with the membrane. Composite membranes of silicalite and Ni-SAPO-34 were also fabricated, but no CO{sub 2}/H{sub 2} selectivity was found. It is proposed to use these membranes for methanol synthesis and separation, and for separating H{sub 2} from gasification products for use as fuel cell fuel, etc.

Falconer, J.; Noble, R.

1995-06-01

203

Salt-occluded zeolite waste forms: Crystal structures and transformability  

SciTech Connect

Neutron diffraction studies of salt-occluded zeolite and zeolite/glass composite samples, simulating nuclear waste forms loaded with fission products, have revealed complex structures, with cations assuming the dual roles of charge compensation and occlusion (cluster formation). These clusters roughly fill the 6--8 {angstrom} diameter pores of the zeolites. Samples are prepared by equilibrating zeolite-A with complex molten Li, K, Cs, Sr, Ba, Y chloride salts, with compositions representative of anticipated waste systems. Samples prepared using zeolite 4A (which contains exclusively sodium cations) as starting material are observed to transform to sodalite, a denser aluminosilicate framework structure, while those prepared using zeolite 5A (sodium and calcium ions) more readily retain the zeolite-A structure. Because the sodalite framework pores are much smaller than those of zeolite-A, clusters are smaller and more rigorously confined, with a correspondingly lower capacity for waste containment. Details of the sodalite structures resulting from transformation of zeolite-A depend upon the precise composition of the original mixture. The enhanced resistance of salt-occluded zeolites prepared from zeolite 5A to sodalite transformation is thought to be related to differences in the complex chloride clusters present in these zeolite mixtures. Data relating processing conditions to resulting zeolite composition and structure can be used in the selection of processing parameters which lead to optimal waste forms.

Richardson, J.W. Jr. [Argonne National Lab., IL (United States). Intense Pulsed Neutron Source Div.

1996-12-31

204

Mechanism of Zeolite Crystallization and Thermochemical Properties of Some Synthetic Zeolites. Final Report.  

National Technical Information Service (NTIS)

During the period of 4/1/82 to 9/30/84, the Department of Energy has provided support for laboratory synthesis of zeolites, calorimetric determinations, and thermal analyses on synthetic zeolites. This Final Report to the DOE is written as 6 independent s...

J. G. Liou

1984-01-01

205

Hot isostatic pressing of glass-zeolite composites.  

National Technical Information Service (NTIS)

Glass-zeolite waste forms are being developed for immobilizing the chloride waste salt generated from the electrometallurgical treatment of spent fuel. Glass-zeolite composites with high densities were made using hot isostatic pressing (HIP) techniques. P...

M. C. Hash C. Pereira M. A. Lewis

1996-01-01

206

11. EASTERN END OF ZEOLITE BUILDING. NOTE DIAL TO LEFT ...  

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

11. EASTERN END OF ZEOLITE BUILDING. NOTE DIAL TO LEFT OF CLOCK GAUGING TOTAL ZEOLITE INFLUENT IN MILLIONS OF GALLONS PER DAY. - F. E. Weymouth Filtration Plant, 700 North Moreno Avenue, La Verne, Los Angeles County, CA

207

Branched vs. linear hydrocarbon separations with novel modified zeolites.  

SciTech Connect

The conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membrane are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.

Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Johnston, Kaylynn; Anderson, Thomas M.

2005-06-01

208

Branched vs. linear hydrocarbon separations with novel modified zeolites.  

SciTech Connect

Conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membranes are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.

Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Anderson, Thomas M.

2004-08-01

209

Separation of xylene mixtures using polyurethane—zeolite composite membranes  

Microsoft Academic Search

Fractionation of o- and p-xylene isomeric mixtures was performed using pervaporation (PV) with polyurethane (PU) membranes containing ZSM zeolite. The xylene vapor sorption isotherms exhibited a Henry's law relationship in this PU–zeolite blend. In binary solutions the individual xylene uptake was also proportional to the solvent composition. Although incorporating zeolite into the PU–zeolite membrane rendered a decrease in xylene solubility

Shingjiang Jessie Lue; Tsai-hsin Liaw

2006-01-01

210

Comparative sorption kinetic studies of ammonium onto zeolite  

Microsoft Academic Search

The sorption kinetics of ammonium onto three types of zeolite, natural zeolite, natural zeolite covered by biofilm and ammonium-bearing zeolite covered by biofilm, at two particle sizes were studied. The pseudo-first order and pseudo-second order models were fitted to the results by a non-linear method. The batch sorption model, based on a pseudo-second order mechanism, was applied to predict the

Donghui Wen; Yuh-Shan Ho; Xiaoyan Tang

2006-01-01

211

A designed organic–zeolite hybrid acid–base catalyst  

Microsoft Academic Search

An organic–zeolite hybrid catalyst was synthesised via solid-state impregnation of the zeolite with an amount of melamine corresponding to 20mol% of the aluminium content. A high density of basic sites is formed in the zeolite. From infrared spectroscopy and TGA measurements we infer that melaminium cations are formed in the zeolite which are highly thermally stable. IR spectroscopic and TGA

Andrew C. Brooks; Liam France; Cecile Gayot; Jerry Pui Ho Li; Ryan Sault; Andrew Stafford; John D. Wallis; Michael Stockenhuber

212

Characterization and environmental application of a Chilean natural zeolite  

Microsoft Academic Search

The use of natural zeolites for environmental applications is gaining new research interests mainly due to their properties and significant worldwide occurrence. The present work describes the characterization of a natural Chilean zeolite and the results as adsorbent for ammonia from aqueous solutions. The zeolitic-rich tuff sample, mainly composed of clinoptilolite and mordenite, consisted of 13 ?m mean volumetric particle

A. H. Englert; J. Rubio

2005-01-01

213

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

214

Removing nitrosamines from mainstream smoke of cigarettes by zeolites  

Microsoft Academic Search

The adsorption of volatile nitrosamines in mainstream smoke of cigarettes by the use of zeolites and other porous materials has been investigated. Zeolites are shown to possess the ability of selectively adsorbing nitrosamines from the mainstream (MS) smoke, and among them, zeolites NaY and ZSM-5 exhibit excellent capacities. The impact of the porous structure and acidity of the adsorbent, the

Yang Xu; Jian Hua Zhu; Li Li Ma; An Ji; Yi Lun Wei; Xi Yong Shang

2003-01-01

215

The efficiency of Jordanian natural zeolite for heavy metals removal  

Microsoft Academic Search

The capability of Jordanian natural zeolite to remove nickel from aqueous solutions was experimentally investigated using a packed bed column. The zeolite samples were obtained from Jabal AL Aritayn in the northeast of Jordan. The effects of the initial concentration of nickel (C0), the packed bed length (L) and the zeolite grain size (Dp) on the adsorption process were considered.

Yazan Taamneh; Yazan TaamnehReyad Al Dwairi

2013-01-01

216

Ion exchange in a zeolite-molten chloride system  

Microsoft Academic Search

Electrometallurgical treatment of spent nuclear fuel results in a secondary waste stream of radioactive fission products dissolved in chloride salt. Disposal plans include a waste form that can incorporate chloride forms featuring one or more zeolites consolidated with sintered glass. A candidate method for incorporating fission products in the zeolites is passing the contaminated salt over a zeolite column for

R. H. Woodman; C. Pereira

1997-01-01

217

Home Modifications  

MedlinePLUS

... understanding of the mechanisms involved. Where Do You Begin? Before you make home modifications, you should evaluate ... rebuildingtogether.org/content/resource/detail/1192/ You can begin your survey by examining each area of your ...

218

Formation of NaA and -X zeolites from waste solutions in conversion of coal fly ash to zeolites  

Microsoft Academic Search

Na-A and -X zeolites were synthesized from waste solutions in conversion of coal fly ash (Fa) to zeolite. The amorphous SiO2 and Al2O3 of Fa were completely dissolved to form Po, Pt, and Pc type zeolites in NaOH solutions at 85°C. Only 24% of Si4+ eluted from Fa were converted to the zeolites and the remaining waste solutions contained high

Hidekazu Tanaka; Yasuhiko Sakai; Ryozi Hino

2002-01-01

219

Controlling chemistry with cations: photochemistry within zeolites.  

PubMed

The alkali ions present in the supercages of zeolites X and Y interact with included guest molecules through quadrupolar (cation-pi), and dipolar (cation-carbonyl) interactions. The presence of such interactions can be inferred through solid-state NMR spectra of the guest molecules. Alkali ions, as illustrated in this article, can be exploited to control the photochemical and photophysical behaviors of the guest molecules. For example, molecules that rarely phosphoresce can be induced to do so within heavy cation-exchanged zeolites. The nature (electronic configuration) of the lowest triplet state of carbonyl compounds can be altered with the help of light alkali metal ions. This state switch (n pi*-pi pi*) helps to bring out reactivity that normally remains dormant. Selectivity obtained during the singlet oxygen oxidation of olefins within zeolites illustrates the remarkable control that can be exerted on photoreactions with the help of a confined medium that also has active sites. The reaction cavities of zeolites, like enzymes, are not only well-defined and confined, but also have active sites that closely guide the reactant molecule from start to finish. The examples provided here illustrate that zeolites are far more useful than simple shape-selective catalysts. PMID:12934881

Ramamurthy, V; Shailaja, J; Kaanumalle, Lakshmi S; Sunoj, R B; Chandrasekhar, J

2003-08-21

220

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

221

Capturing Ultrasmall EMT Zeolite from Template-Free Systems  

NASA Astrophysics Data System (ADS)

Small differences between the lattice energies of different zeolites suggest that kinetic factors are of major importance in controlling zeolite nucleation. Thus, it is critical to control the nucleation kinetics in order to obtain a desired microporous material. Here, we demonstrate how careful investigation of the very early stages of zeolite crystallization in colloidal systems can provide access to important nanoscale zeolite phases while avoiding the use of expensive organic templates. We report the effective synthesis of ultrasmall (6- to 15-nanometer) crystals of the large-pore zeolite EMT from template-free colloidal precursors at low temperature (30°C) and very high yield.

Ng, Eng-Poh; Chateigner, Daniel; Bein, Thomas; Valtchev, Valentin; Mintova, Svetlana

2012-01-01

222

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

223

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

224

Crystal engineering of zeolites with graphene.  

PubMed

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. PMID:24853328

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

2014-06-12

225

Reorientational dynamics of water confined in zeolites.  

PubMed

We present a detailed molecular-dynamics study of water reorientation and hydrogen-bond dynamics in a strong confinement situation, within the narrow pores of an all-silica Linde type A (LTA) zeolite. Two water loadings of the zeolite are compared with the bulk case. Water dynamics are retarded in this extreme hydrophobic confinement and the slowdown is more pronounced at higher water loading. We show that water reorientation proceeds mainly by large-amplitude angular jumps, whose mechanism is similar to that determined in the bulk. The slowdown upon hydrophobic confinement arises predominantly from an excluded-volume effect on the large fraction of water molecules lying at the interface with the zeolite matrix, with an additional minor contribution coming from a structuring effect induced by the confinement. PMID:24449592

Fogarty, Aoife C; Coudert, François-Xavier; Boutin, Anne; Laage, Damien

2014-02-24

226

Spontaneous proton transfer in Na zeolites  

NASA Astrophysics Data System (ADS)

First-principles room-temperature molecular dynamics (MD) simulations are conducted to investigate proton transfer (PT) in Na zeolites. The MD are performed on the unit cell containing two Al-sites, one of them saturated with H (acid site) and the second one with Na coordinated with three water molecules. The creation of the charged H 3O + cations is suppressed by the Na cation. Spontaneous barrierless PT between the O-sites in the zeolite, however, is possible. The lifetime of the hydronium cation is extremely short (?5 fs). The presence of Na + cations leads to a modified mechanism but does not suppress the proton transfer around the Al-site in zeolites.

Benco, L.; Demuth, T.; Hafner, J.; Hutschka, F.

2000-11-01

227

Natrolite: A zeolite with negative Poisson's ratios  

NASA Astrophysics Data System (ADS)

The recently published experimental elastic constants [C. Sanchez-Valle, S. V. Sinogeikin, Z. A. Lethbridge, R. I. Walton, C. W. Smith, K. E. Evans, and J. D. Bass, J. Appl. Phys. 98, 053508 (2005)] for single crystals of the orthorhombic aluminosilicate zeolite NAT (natrolite, Na2(Al2Si3O10)2H2O, Fdd2) throw valuable light on the potential of NAT as a material which exhibits single crystalline negative Poisson's ratios (auxetic). On performing an off-axis analysis of these elastic constants we confirm that the zeolite natrolite exhibits auxetic behavior in the (001) plane. This supports our preliminary report that NAT-type zeolites exhibit auxetic behavior through a mechanism involving microscopic rotation of semi-rigid structural units.

Grima, Joseph N.; Gatt, Ruben; Zammit, Victor; Williams, Jennifer J.; Evans, Kenneth E.; Alderson, Andrew; Walton, Richard I.

2007-04-01

228

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

229

Quasi all-silica zeolite obtained by isomorphous degermanation of an as-made germanium-containing precursor.  

PubMed

Ge-containing ITQ-22 zeolites have been almost completely degermanated under strong acidic conditions without modifications of the framework topology. Simultaneous to Ge extraction, the framework was partially dissolved; mesopores were formed but the structure was maintained through the re-incorporation of some of silicon species at vacant sites. The presence of many defects in the degermanated framework enabled the incorporation of tetrahedral aluminum, opening the way to the preparation of new and stable acid catalysts with original topologies. PMID:24375808

Burel, Laurence; Kasian, Nataliia; Tuel, Alain

2014-01-27

230

Photophysical properties of metal ion functionalized NaY zeolite.  

PubMed

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu(3+), Tb(3+), Ce(3+), Y(3+), Zn(2+), Cd(2+), Cu(2+)) exchanged zeolite, rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Y(3+) and rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Zn(2+) are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare-earth ion broadens the application of zeolite as a luminescent host. The Eu(3+) ion exchanged zeolite shows white light luminescence with a great application value and Ce(3+) exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite. PMID:24392790

Duan, Tian-Wei; Yan, Bing

2014-01-01

231

Solar cogeneration for copper smelting  

SciTech Connect

Work is reported on designing a system for solar repowering of a cogenerating flash smelting furnace that produces copper and sulfuric acid. Smelter energy requirements are listed and the proposed project is described. Several modifications to existing equipment and additional investment in the plant are listed that are necessary as a result of the solar power system improvement. Expected enhancements of the smelting process performance are discussed and the economics of the project are examined. (LEW)

Curto, P. (Gibbs and Hill, Inc., New York, NY); Gillespie, A.

1981-01-01

232

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

233

Thermal properties of zeolites: effective thermal conductivity of dehydrated powdered zeolite 4A  

Microsoft Academic Search

The determination of the subambient effective thermal conductivity of evacuated powdered zeolite 4A is described. The results are modelled successfully in terms of boundary scattering, point defects and three-phonon Umklapp processes.

Vladimir V. Murashov; Mary Anne White

2002-01-01

234

Skeletal isomerization of 1-butene over ferrierite and ZSM-5 zeolites: influence of zeolite acidity  

Microsoft Academic Search

Three ferrierite (FER) and five ZSM-5 (MFI) zeolites with SiO2Al2O3 ratio ranging from 27 to 2000 are tested as catalysts for the skeletal isomerization of 1-butene at 350–450°C and atmospheric total pressure in order to study the influence of acidity and pore structure of zeolite on conversion and selectivity. The catalytic and NH3 temperature-programmed desorption results from FER and MFI

Gon Seo; Hwan Seok Jeong; Suk Bong Hong; Young Sun Uh

1996-01-01

235

Effect of zeolites on chitosan\\/zeolite hybrid membranes for direct methanol fuel cell  

Microsoft Academic Search

Zeolites including 3A, 4A, 5A, 13X, mordenite, and HZSM-5 were incorporated into chitosan (CS) matrix to fabricate the hybrid membranes for direct methanol fuel cell (DMFC). Due to the presence of hydrogen bonds between CS and zeolite, the hybrid membranes displayed desirable thermal and mechanical stabilities. Through free volume characteristics analysis by positron annihilation lifetime spectroscopy (PALS) technique, it was

Jingtao Wang; Xiaohong Zheng; Hong Wu; Bin Zheng; Zhongyi Jiang; Xiaopeng Hao; Baoyi Wang

2008-01-01

236

Copper Cleanup  

NSDL National Science Digital Library

In this hands-on experiment, kids use chemistry to explore whether acids or bases are better at restoring a pennyâs shine. Kids follow the scientific process to test a common household cleaning products alongside ketchup, cola, and other kitchen staples, and may be surprised by the results! A downloadable data sheet is available on the Copper Cleanup activity resources page.

Wgbh

2010-01-01

237

MCM-41 impregnated with A zeolite precursor: Synthesis, characterization and tetracycline antibiotics removal from aqueous solution  

PubMed Central

In this paper, the MCM-41 has been modified by impregnation with zeolite A to prepare a kind of new adsorbent. The adsorption of TC from aqueous solutions onto modified MCM-41 has been studied. It was discovered that the adsorption capability of zeolite A modified MCM-41 (A-MCM-41) increased dramatically after modification. The modified MCM-41 was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier Transform Infrared (FTIR) analysis, Transmission electron microscopy (TEM) images, and 29Si and 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectra. The modified MCM-41 structure was still retained after impregnated with zeolite A but the surface area and pore diameter decreased due to pore blockage. The adsorption of TC on modified MCM-41 was discussed regarding various parameters such as pH, initial TC concentration, and the reaction time. The pH effects on TC adsorption indicated that the adsorbents had better adsorption performances in acidic and neutral conditions. The adsorption isotherms were fitted well by the Langmuir model. The adsorption kinetics was well described by both pseudo-second order equation and the intra-particle diffusion model. The adsorption behavior in a fixed-bed column system followed Thomas model. The adsorption behavior of TC was the chemical adsorption with an ion exchange process and electrostatic adsorption.

Liu, Minmin; Hou, Li-an; Yu, Shuili; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

2013-01-01

238

Plasma Treatment and Surface Analysis of Polyimide Films for Electroless Copper Buildup Process  

Microsoft Academic Search

b Intel Corporation, Assembly Technology Development, Chandler, Arizona 85226, USA We report here a detailed characterization of the surface chemical states and morphology of polyimide PI films following modifications by plasma treatment and electroless copper deposition. NH3 and Ar plasma treatments have been successfully used to achieve morphological and chemical modification of the PI surface so that electroless copper plating

Dhananjay Bhusari; Harley Hayden; Ravindra Tanikella; Sue Ann Bidstrup Allen; Paul A. Kohla

2005-01-01

239

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

240

Electrical properties of zeolitized volcaniclastic materials  

Microsoft Academic Search

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

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

2002-01-01

241

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

242

ARSENIC SEPARATION FROM WATER USING ZEOLITES  

EPA Science Inventory

Arsenic is known to be a hazardous contaminant in drinking water. The presence of arsenic in water supplies has been linked to arsenical dermatosis and skin cancer . Zeolites are well known for their ion exchange capacities. In the present work, the potential use of a variety of ...

243

Reactions of aliphatic ketones on zeolites  

Microsoft Academic Search

Reactions of some ketones (acetone, methyl ethyl ketone and diethyl ketone) on the H-form of ZSM-5, ZSM-11, mordenite and erionite have been studied in an integral reactor. At a reaction temperature of 300 or 350°C acetone is selectively transformed on all these zeolites into isobutene, while with higher ketones substantial amounts of aromatics are formed.

K. Nedomová; S. Beran

1986-01-01

244

ARSENIC SEPARATION FROM WATER USING ZEOLITES: SYMPOSIUM  

EPA Science Inventory

NRMRL-ADA-01134 Shevade, S, Ford*, R., and Puls*, R.W. "Arsenic Separation from Water Using Zeolites." In: 222nd ACS National Meeting, ACS Environmental Chemistry Division Symposia, Chicago, IL, 08/26-30/2001. 2001. 04/23/2001 This...

245

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

246

MERCURY SEPARATION FROM POLLUTANT WATER USING ZEOLITES  

EPA Science Inventory

Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water has been examined at room temperature. Experiments have...

247

In situ DRIFTS-MS studies on the oxidation of adsorbed NH3 by NOx over a Cu-SSZ-13 zeolite  

SciTech Connect

DRIFT spectroscopy combined with mass spectrometry was used to investigate the oxidation of adsorbed ammonia by NO2, NO+O2 and NO2+O2 on a copper ion exchanged SSZ 13 (Cu-SSZ-13) zeolite. Compared with both NO2 and NO, the adsorption of ammonia is much stronger on the Cu-SSZ-13 zeolite. Two adsorbed ammonia species were found over the Cu-SSZ-13 zeolite studied here; notably ammonia on Brönsted acid sites (proton) and ammonia on Lewis acid sites (copper ions). These adsorbed ammonia species present different activity profiles and selectivity to N2 during NH3 oxidation. The results obtained suggest that ammonia adsorbed onto copper ions in Cu-SSZ-13 are more active at low temperatures than proton-adsorbed NH3, and give rise to a higher selectivity to N2. The formation of N2O is associated primarily with the reaction of NOx with proton-adsorbed NH3 via the formation and subsequent thermal decomposition of NH4NO3. Financial support was provided by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. Portions of this work were 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.

Zhu, Haiyang; Kwak, Ja Hun; Peden, Charles HF; Szanyi, Janos

2013-04-30

248

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...

249

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

250

PDV modifications.  

SciTech Connect

External modifications can transform a conventional photonic doppler velocimetry (PDV) system to other useful configurations - Non-standard probes and Frequency-conversion measurements. This approach is easier than supporting every conceivable measurement in the core PDV design. Circulator specifications may be important - -30 dB isolation (common) probably not be enough, -50 dB isolation is available, and some bench testing may be needed.

Dolan, Daniel H., III

2010-09-01

251

Dispersion strengthened copper  

DOEpatents

A composition of matter is described which is comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide. A method for making this composition of matter is also described. This invention relates to the art of powder metallurgy and, more particularly, it relates to dispersion strengthened metals.

Sheinberg, H.; Meek, T.T.; Blake, R.D.

1990-01-09

252

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

253

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

254

Zeolite catalysis in conversion of cellulosics. Annual report  

SciTech Connect

The authors have studied the kinetics of oxylose/xylulose isomerization in significant detail over a variety of zeolites and obtained the pseudo-first order reaction rate constants. The authors have found that HY zeolite is still the best material and zeolites are more selective than homogeneous acid catalysts where decomposition of the sugar compounds is much faster. They have completed, as described in the Year 2 Work Plan, the study of cellobiose hydrolysis with an ion exchange resin. The kinetics of the solid-catalyzed reaction is qualitatively similar to that for catalysis by homogeneous acids. The planned program of NMR studies has revealed the dynamics of sugar molecules within the zeolite cavities. Two chemisorbed and a physisorbed state have been identified in HY zeolite. A new state, accounting for as much as a half of the sugar, has been found in ZSM-5 zeolite.

Tsao, G.T.

1994-02-01

255

Atomic sites and stability of Cs+ captured within zeolitic nanocavities  

PubMed Central

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 137Cs+ 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.

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

2013-01-01

256

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

257

Evaporated copper on surface modified polyaniline films  

NASA Astrophysics Data System (ADS)

In order to improve the adhesion between the emeraldine base (EB) film of polyaniline (PANI) and evaporated copper metal, surface modification of EB films via UV-induced graft copolymerization with glycidyl methacrylate (GMA) was carried out. The effects of GMA monomer concentration and UV graft copolymerization time on the T-peel adhesion strength of the resulting Cu/EB laminates were studied. It was found that the adhesion strength between the GMA graft-copolymerized EB (GMA-g-EB) film and evaporated copper increased monotonically with the graft concentration of the GMA polymer. The T-peel adhesion strength between the surface-modified EB film and evaporated copper was increased by almost 10-folds under the optimum surface modification conditions. The chemical compositions of the GMA-g-EB surfaces were studied by X-Ray photoelectron spectroscopy (XPS). The interaction between the GMA-g-EB surface and the deposited copper atoms was investigated in situ by XPS. The epoxide groups of the grafted GMA polymer interacted with the evaporated copper atoms to form a charge-transfer complex, which accounted for the enhanced adhesion of evaporated copper to the GMA-g-EB films.

Ma, Z. H.; Tan, K. L.; Chua, W. S.; Kang, E. T.; Neoh, K. G.

2001-03-01

258

Development of low-cost integrated zeolite collector  

NASA Astrophysics Data System (ADS)

The optimum zeolite loading and the best zeolite for this purpose were determined by careful mathematical analysis, followed by experimental test, to confirm the theoretical results. The integrated collector design was then completed and the collector was constructed. After sealing and vacuum testing the zeolite panels and heat exchanges, the collector was coated with flat black paint and provided with double glazing, aluminum frame and insulation. Preliminary testing indicates close agreement with theoretical predictions of its performance.

Tchernev, D. I.

1981-07-01

259

Random walk theory of reaction kinetics in zeolites  

Microsoft Academic Search

We discuss application of the continuous-time random walk (CTRW) model to studying the kinetics of pseudo-first-order reactions in zeolites. The model includes distance-dependent reaction mechanism, details of the zeolite structure, and dynamics of migration of guest molecules between adsorption sites. Diffuse-reflectance transient-absorption study of triplet anthracene quenching by azulene in NaY zeolite shows that quenching can occur when reactants are

A. V. Barzykin; S. Hashimoto

2000-01-01

260

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

261

Abnormalities of cation movements in 3A zeolite  

Microsoft Academic Search

The dielectric spectra of dehydrated and partially hydrated 3A zeolites with the cation composition of Na6.1K5.9-A were measured to investigate movements of cations in the zeolite (‘A’ stands for the framework of A zeolite). The spectra of dehydrated state showed two relaxations (relax I in the lower frequency side and relax II in the higher frequency side) in the ranges

Tatsuo Ohgushi; Yuya Sakai; Yoshimichi Adachi

262

Polyfuran\\/zeolite LTA composites and adsorption properties  

Microsoft Academic Search

Composites of polyfuran (PFu) with LTA type (3A, 4A, 5A) zeolites were prepared via chemical oxidative polymerization of furan (Fu) in the presence of a dispersion of zeolites (powder) in ACN solvent using anhydrous FeCl3 oxidant at an ambient temperature. The composites were characterized by Fourier transform infrared spectroscopic (FTIR) analysis. FTIR results showed that the composites of 3A zeolite

Songül ?en; Belgin Bardakç?; Ay?e Gül Yavuz; Ay?egül Uygun Gök

2008-01-01

263

Adsorption of CO on LTA zeolite adsorbents: An IR investigation  

Microsoft Academic Search

The low temperature adsorption of CO on the zeolites K-LTA (3A) Na-LTA (4A) and Ca,Na-LTA (5A) has been investigated by IR spectroscopy. For comparison, the adsorption of CO on K-MOR, Na-MOR and Ca-MOR has also been studied. CO adsorption on K-LTA zeolite is mostly limited at the external surface. In the case of Na-LTA zeolite, terminal Na+ carbonyls are formed.

Tania Montanari; Isabel Salla; Guido Busca

2008-01-01

264

Predicting locations of non-framework species in zeolite materials  

Microsoft Academic Search

A new grid-based algorithm developed at Molecular Simulations, and molecular dynamics method have been applied to modeling the locations of non-framework species in zeolites. This new method locates the energy minima for various frameworks and populates these sites with the non-framework species. The cation locations were predicted in dehydrated zeolite adsorbents and catalysts, such as Na88X, Ca48X, mixed cation zeolite

V. V. Guliants; J. T. Mullhaupt; J. M. Newsam; A. M. Gorman; C. M. Freeman

1999-01-01

265

Methane partial oxidation in iron zeolites: theory versus experiment  

Microsoft Academic Search

The conversion of methane to methanol over zeolitic ?-oxygen sites has been demonstrated using Fe-ZSM-5. To discriminate between mono- and poly-nuclear active sites, we prepared the [Fe]-ZEO with iron in the ZEOlite lattice via direct synthesis and Fex-ZEO, by dispersion of xwt.% iron on the ZEOlite. Shape-selective formation of nano-clusters of iron oxides with various sizes is realized inside the

P. P. Knops-Gerrits; W. A. Goddard

2001-01-01

266

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

267

Zeolite-chrome tanning: From laboratory to pilot scale  

Microsoft Academic Search

Synthetic Na-zeolites (NaA, NaX, NaAX) were investigated as tanning agents in leather production from sheepskin and calfskin pelts. It was found in laboratory scale testing that the combined use of zeolite and chrome sulphate results in both higher float exhaustion and higher shrinkage temperatures in shorter time than in conventional chrome tannage. The best results were obtained with zeolite NaA.

P. Ciambelli; D. Sannino; B. Naviglio; A. M. Manna; V. Vaiano; G. Calvanese; G. Vietri; S. Gallo

2005-01-01

268

NMR Study on the Acidity of TS1 Zeolite  

Microsoft Academic Search

The acidic properties of TS-1 and Silicalite-1 zeolites have been investigated by the solid-state MAS NMR technique capable of in situ sample pretreatment. As shown by a combination of the 31P MAS NMR and 1H MAS NMR techniques with trimethylphosphine, not only Brønsted acid sites but also Lewis acid sites exist in the TS-1 zeolites. Moreover, TS-1 zeolite is more

Jianqin Zhuang; Zhimin Yan; Xiumei Liu; Xianchun Liu; Xiuwen Han; Xinhe Bao; Ulrich Mueller

2002-01-01

269

Synthesis of Hierarchical TS1 Zeolite from Silanized Seeds  

Microsoft Academic Search

Hierarchical TS-1 zeolites with a bimodal pore architecture, consisting of the typical MFI micropores and an additional mesoporosity,\\u000a have been synthesized by grafting an organosilane compound to the zeolitic seeds previously prepared from two different raw\\u000a materials: a liquid gel and an amorphous SiO2–TiO2 xerogel. These hierarchical TS-1 zeolites show an excellent catalytic behavior in olefin epoxidation reactions employing\\u000a organic

D. P. Serrano; R. Sanz; P. Pizarro; I. Moreno

2010-01-01

270

Cigarette smoke extract inhibits oxidative modification of low density lipoprotein  

Microsoft Academic Search

Oxidative modification of low density lipoprotein (LDL) by cigarette smoke has been suggested in several recent studies. To characterize possible modification of LDL by cigarette smoke extract (CSE), we incubated LDL with CSE either in the presence or absence of the chemical pro-oxidants, cupric chloride or 2,2?-azo-bis(2-amidinopropane) hydrochloride (AAPH). Surprisingly, CSE inhibited oxidative modification of LDL induced by either copper

Chen Chen; George Loo

1995-01-01

271

Rapid crystallization of faujasitic zeolites: mechanism and application to zeolite membrane growth on polymer supports.  

PubMed

Zeolites are microporous, crystalline aluminosilicates with the framework made up of T-O-T (T = Si, Al) bonds and enclosed cages and channels of molecular dimensions. Influencing and manipulating the nucleation and growth characteristics of zeolites can lead to novel frameworks and morphologies, as well as decreased crystallization time. In this study, we show that manipulating the supersaturation during synthesis of zeolite X/Y (FAU) via dehydration led to extensive nucleation. Controlled addition of water to this nucleated state promotes the transport of nutrients, with a 4-fold increase in the rate of crystal growth, as compared to conventional hydrothermal process. Structural signature of the nucleated state was obtained by electron microscopy, NMR, and Raman spectroscopy. This extensively intermediate nucleated state was isolated and used as the starting material for zeolite membrane synthesis on porous polymer supports, with membrane formation occurring within an hour. With this time frame for growth, it becomes practical to fabricate zeolite/polymer membranes using roll-to-roll technology, thus making possible new commercial applications. PMID:24758695

Severance, Michael; Wang, Bo; Ramasubramanian, Kartik; Zhao, Lin; Ho, W S Winston; Dutta, Prabir K

2014-06-17

272

Copper Extraction Demonstration  

NSDL National Science Digital Library

Summary This demonstration uses sulfuric acid and crushed copper ore (malachite) to produce a solution of copper sulfate and carbonic acid in a beaker. When a freshly sanded nail is dropped into the copper sulfate ...

273

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

274

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

275

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

276

Thermodynamic analysis of a solar zeolite refrigeration system  

SciTech Connect

A solar zeolite-water absorption refrigeration unit was studied. Thermodynamic expressions were derived to predict the system performance. The operating range and optimum design parameters for the zeolite system were determined. The main parameters governing performance were: solar collector type, ambient temperature, and absorber properties. Results are shown for various solar collector types and various zeolite types. A desorption initiation temperature is shown to exist. The analysis is not based on empirical heat of absorption data, but rather on a zeolite properties relationship (log P /SUB v/ versus 1/T /SUB z/ ) to determine system performance.

Chang, S.C.; Roux, J.A.

1985-08-01

277

Anomalous strain behavior in CO2-saturated zeolitic tuffs  

NASA Astrophysics Data System (ADS)

Zeolites are aluminosilicate minerals with open, cage-like structures and negatively charged frames. Some naturally-occurring zeolites are stabile at geothermal temperatures and have cage structures large enough that small molecules can traverse the intracrystalline cage network easily. This, in addition to their negatively-charged frames, makes these zeolites strong adsorbents (and potentially absorbents) of carbon dioxide. We present a short series of experiments to determine what mechanical effects result from carbon dioxide interaction with zeolitic tuff samples. Three samples were tested: a non-zeolitized grey tuff from the Campi Flegrei region, a zeolitized yellow tuff from the same region, and a zeolite-rich tuff from southern California. The samples were tested in a hydrostatic pressure vessel up to 12 MPa confining pressure. Strains and ultrasonic acoustic velocities were measured under dry conditions as well as during helium injection and carbon dioxide injection. Results show acoustic velocities depend only on differential pressure and not on pore fluid type. Both zeolitized tuffs show decreased strain with gaseous carbon dioxide in the pore space; the decreased strain (or swelling) represents an 8%-16% deviation from the total strain in the helium-saturated case. This indicates that it is the interaction between zeolite minerals and carbon dioxide causing the anomalous strain readings.

Dralus, D. E.; Vanorio, T.; Mavko, G. M.

2012-12-01

278

LAYER-BY-LAYER ASSEMBLY OF NANOZEOLITE BASED ON POLYMERIC MICROSPHERE: ZEOLITE COATED SPHERE AND HOLLOW ZEOLITE SPHERE  

Microsoft Academic Search

Zeolite ?, silicalite-1, ZSM-5, and TS-1 coated spheres have been prepared successfully through layer-by-layer assembly of nanozeolite\\/polymer multilayers on polystyrene (PS) microspheres, and hollow zeolite spheres have been obtained by removal of the core by calcination. In the adsorption process of nanozeolites onto the polyelectrolyte-modified template spheres, it has been found that zeta potential of the zeolite colloidal solution that

Wuli Yang; Xingdong Wang; Yi Tang; Yajun Wang; Chen Ke; Shoukuan Fu

2002-01-01

279

Computational studies of water adsorption in zeolites  

SciTech Connect

We have performed high-level ab initio calculations using Hartree-Fock (HF) theory, Moller-Plesset perturbation theory (MP2), and density-functional theory (DFT) to study the geometry and energetics of the adsorption complex involving H{sub 2}O and the Bronsted acid site in the zeolite H-ZSM-5. These calculations use aluminosilicate cluster models for the zeolite framework with as many as 28 T atoms (T=Si, Al). We included geometry optimization in the local vicinity of the acid site at the MP2 and DFT levels of theory for the smallest cluster, while in the larger clusters this was done at the HF/6-31G(d) level of theory. We have also calculated corrections for zero-point energies, extensions to higher basis sets, and higher levels of electron correlation. Results for the adsorption energy and geometry of this complex are reported and compared with previous theoretical and experimental values.

Zygmunt, S.A. [Valparaiso Univ., IN (United States); Curtiss, L.A.; Iton, L.E. [Argonne National Lab., IL (United States)

1995-05-01

280

Pf/Zeolite Catalyst for Tritium Stripping  

SciTech Connect

This report described promising hydrogen (protium and tritium) stripping results obtained with a Pd/zeolite catalyst at ambient temperature. Preliminary results show 90-99+ percent tritium stripping efficiency may be obtained, with even better performance expected as bed configuration and operating conditions are optimized. These results suggest that portable units with single beds of the Pd/zeolite catalyst may be utilized as ''catalytic absorbers'' to clean up both tritium gas and tritiated water. A cart-mounted prototype stripper utilizing this catalyst has been constructed for testing. This portable stripper has potential applications in maintenance-type jobs such as tritium line breaks. This catalyst can also potentially be utilized in an emergency stripper for the Replacement Tritium Facility.

Hsu, R.H.

2001-03-26

281

Electrical Response of PEDOT-PSS/FAU Zeolite Composites toward SO2: Controlling the Adsorption Properties of FAU Zeolite  

NASA Astrophysics Data System (ADS)

In our work, we propose to combine a conductive polymer, Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT-PSS), with FAU zeolites to investigate the potential of the composites for use as SO2 sensing materials.Composites with PEDOT-PSS as a matrix containing faujasite zeolites of various cation types (divalent transition metal ions: Fe^2+, Co^2+, Ni^2+ and Cu^2+), were fabricated to investigate the effect of the cation type of the faujasite zeolites on the electrical conductivity response when exposed to SO2. The composite was tested through repeated sensing and recovery processes to investigate the reversibility and reproducibility. During the recovery process, the electrical conductivity of the composites were recovered, which proves that the sensing characteristics are repeatable. Responses and the interaction mechanism of the conductive polymer/zeolite composites were investigated. The composite with 20% (v/v) of zeolite content gives the highest sensitivity. The electrical conductivity responses of PEDOT-PSS/Zeolite composites can be altered due to the available adsorption sites for gas molecules. The addition of zeolites to the pristine PEDOT-PSS improved the electrical conductivity sensitivity of the composites by enhancing the interaction between PEDOT-PSS and SO2. The type of cation in the zeolite pores effected the sensitivity of the composites, depending on the acidity of the ion-exchanged zeolites.

Chanthaanont, Pojjawan; Sirivat, Anuvat

2012-02-01

282

Framework Stability and Brønsted Acidity of Isomorphously Substituted Interlayer-Expanded Zeolite COE-4: A Density Functional Theory Study.  

PubMed

COE-4 zeolites possess a unique two-dimensional ten-ring pore structure with the Si(OH)2 hydroxyl groups attached to the linker position between the ferrierite-type layers, which has been demonstrated through the interlayer-expansion approach in our previous work (H. Gies et al. Chem. Mater.- 2012, 24, 1536). Herein, density functional theory is used to study the framework stability and Brønsted acidity of the zeolite T-COE-4, in which the tetravalent Si is isomorphously substituted by a trivalent Fe, B, Ga, or Al heteroatom at the linker position. The influences of substitution energy and equilibrium geometry parameters on the stability of T-COE-4 are investigated in detail. The relative acid strength of the linker position is revealed by the proton affinity, charge analysis, and NH3 adsorption. It is found that the range of the ?T-O-Si? angles is widened to maintain the stability of isomorphously substituted T-COE-4 zeolites. The smaller the ?O1-T-O2? bond angle is, the more difficult is to form the regular tetrahedral unit. Thus, the substitution energies at the linker positions increase in the following sequence: Al-COE-4 < Ga-COE-4 < Fe-COE-4 < B-COE-4. The adsorption of NH3 as a probe molecule indicates that the acidity can affect the hydrogen-bonding interaction between (N?H???O2) and (N???H?O2). The relative Brønsted-acid strength of the interlayer-expanded T-COE-4 zeolite decreases in the order of Al-COE-4 > Ga-COE-4 > Fe-COE-4 > B-COE-4. These findings may be helpful for the structural design and functional modification of interlayer-expanded zeolites. PMID:24644296

Li, Haichao; Zhou, Danhong; Tian, Dongxu; Shi, Chuan; Müller, Ulrich; Feyen, Mathias; Yilmaz, Bilge; Gies, Hermann; Xiao, Feng-Shou; De Vos, Dirk; Yokoi, Toshiyuki; Tatsumi, Takashi; Bao, Xinhe; Zhang, Weiping

2014-06-01

283

Synthesis of zeolitic imidazolate framework films and membranes with controlled microstructures.  

PubMed

Zeolitic imidazolate frameworks (ZIFs) are hybrid organic-inorganic microporous materials that exhibit zeolite-like structures and can be synthesized with a wide range of pore sizes and chemical functionality. ZIFs as thin films and membranes are of interest for their applications in sensors and gas separation. Here, we report a method for ZIF film and membrane fabrication, based on support surface modification and in situ solvothermal growth, which has potential for general application to other ZIF membranes. Our simple surface modification method results in strong covalent bonds between ?-Al(2)O(3) supports and imidazolate ligands, which promote the heterogeneous nucleation and growth of ZIF crystals. The microstructure of ZIF-8 films can be controlled by controlling the pH of the growth solution. ZIF-7 films were fabricated to demonstrate the potential for general applicability of our method. Finally, the separation performance of several ZIF-8 membranes was evaluated, revealing molecular sieving behavior with an ideal selectivity for H(2)/CH(4) of 13. PMID:20731336

McCarthy, Michael C; Varela-Guerrero, Victor; Barnett, Gregory V; Jeong, Hae-Kwon

2010-09-21

284

A new family of two-dimensional zeolites prepared from the intermediate layered precursor IPC-3P obtained during the synthesis of TUN zeolite.  

PubMed

The crystallization of zeolite TUN with 1,4-bis(N-methylpyrrolidinium)butane as template proceeds through an intermediate, designated IPC-3P, following the Ostwald rule of successive transformations. This apparently layered transient product has been thoroughly investigated and found to consist of MWW monolayers stacked without alignment in register, that is, disordered compared with MCM-22P. The structure was confirmed based on X-ray diffraction and high-resolution (HR)TEM analysis. The layered zeolite precursor IPC-3P can be swollen and pillared affording a combined micro- and mesoporous material with enhanced Brunauer-Emmett-Teller (BET) surface area (685?m(2) g(-1) ) and greater accessibility of Brønsted acid sites for bulky molecules. This mesoporous material was probed with 2,6-di-tert-butylpyridine (DTBP). IPC-3P and its modification create a new layered zeolite sub-family belonging to the MWW family. FTIR data indicate that (Al)MWW materials MCM-22 and IPC-3 with Si/Al ratios greater than 20 exhibit a lower relative ratio of Brønsted to Lewis acid sites than MCM-22 (with Si/Al ratios of around 13), that is, less than 2 versus more than 3, respectively. This is maintained even upon pillaring and warrants further exploration of materials like IPC-3P with a higher Al content. The unique XRD features of IPC-3P indicating misaligned stacking of layers and distinct from MCM-22P, are also seen in other MWW materials such as EMM-10P, hexamethonium-templated (HM)-MCM-22, ITQ-30, and UZM-8 suggesting the need for more detailed study of their identity and properties. PMID:24038214

Kub?, Martin; Roth, Wieslaw J; Greer, Heather F; Zhou, Wuzong; Morris, Russell E; P?ech, Jan; ?ejka, Ji?í

2013-10-01

285

Water splitting by titanium exchanged zeolite A  

Microsoft Academic Search

Analysis of the product resulting from the equilibration 25 g of zeolite A with 50 cc of unstirred 20% titanium chloride solution for 1 h at ambient temperature indicated that 75% of the potassium cations are replaced by titanium cations on the surface of the ¹\\/ââ in.-diameter Linde 3A particles; the cages probably remained intact since little aluminum leaching occurred.

Steven M. Kuznicki; Edward M. Eyring

1978-01-01

286

VS1 zeolite synthesized directly from silatrane  

Microsoft Academic Search

VS-1 zeolite was successfully synthesized using silatrane as the precursor via sol–gel processing and microwave heating methods. Various factors, which influence the product properties, were investigated, viz. water content, reaction temperature, sodium hydroxide concentration, and amount of vanadium loading. XRD, SEM, UV–visible and ESR were applied to characterize synthesized VS-1. Lower water content and higher temperature promote incorporation of vanadium

Phairat Phiriyawirut; Alexander M. Jamieson; Sujitra Wongkasemjit

2005-01-01

287

Solar energy application of natural zeolites  

Microsoft Academic Search

The utilization of solar energy for cooling is usually achieved by means of sorption-refrigeration cycles. However, the conventional cycles using ammonia-water or lithium bromide-water solutions are inefficient because of the low solution temperatures obtainable with solar radiation and the high condenser temperatures required by air-cooled condensers. Zeolites provide a unique opportunity for a solid-gas adsorption cooling system because of their

D. I. Tchernev

1978-01-01

288

Transformation of thiophenic compounds over HY zeolite  

Microsoft Academic Search

The transformation of thiophenic compounds (2-methylthiophene, 3-methylthiophene, 2-methylbenzothiophene and 3-methylbenzothiophene) was carried out in a fixed bed reactor at 350°C under atmospheric pressure in the presence of a HY zeolite with a Si\\/Al ratio equal to 16. All the reactants underwent both isomerization and disproportionation. The product selectivities obtained experimentally were rationalized on the basis of the calculated stabilities (B3LYP

F. Richard; T. Boita; M. Moreau; C. Bachmann; G. Pérot

2007-01-01

289

Transformation of thiophenic compounds over acidic zeolites  

Microsoft Academic Search

The transformation of thiophenic compounds (2-methylthiophene; 3-methylthiophene; 2,3-dimethylthiophene; 2,5-dimethylthiophene; 2-methylbenzothiophene; 3-methylbenzothiophene) was carried out over HY zeolite at 350°C under atmospheric pressure in a fixed bed reactor. The transformation of some of them was also carried out over H?, HZSM5 and H-mordenite (HMOR). In the presence of HY, all the reactants underwent both isomerization and disproportionation in various proportions depending

T. Boita; M. Moreau; F. Richard; G. Pérot

2006-01-01

290

Preparing Copper Powder from Cemented Copper.  

National Technical Information Service (NTIS)

Techniques were developed for preparing metallurgical-grade copper powder from industrially produced cement copper. Flotation was used for rejecting discrete gangue particles, acid leaching to remove residual iron and aluminum, hydrogen reduction to elimi...

J. K. Winter L. G. Evans R. D. Groves

1971-01-01

291

Quantitatively probing the Al distribution in zeolites.  

PubMed

The degree of substitution of Si(4+) by Al(3+) in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. Because 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 (27)Al 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 an HBEA150 zeolite has been determined using this analysis. PMID:24815517

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

2014-06-11

292

Anchoring strategies for bimetallic species in zeolites  

SciTech Connect

We explore a new approach by introducing heterobinuclear organometallic compounds for linking catalytic functions to zeolite frameworks. With two different metals present, the complexes are being anchored to the support via one oxophilic metal, ligand exchange and catalytic reactions may proceed at the second metal center. Anchoring chemistry, thermal stability and reactivity of Me[sub 3]SnMn(CO)[sub 5] in zeolite NaY and acid forms of zeolite Y was studied with X-ray absorption spectroscopy (Sn, Mn edge EXAFS) and in-situ FTIR/TPD-MS techniques. Subsequently, the tin-cobalt complex Me[sub 3]SnCo(CO)[sub 4] has been a focus of detailed synthetic and spectroscopic studies. The reactivity of tricarbonyl (cyclopentadienyl) (trimethylstannyl) molybdenum in new mesoporous hosts has been explored. A recent development is the design of vanadium oxo species in different micro- and mesoporous hosts. These are of great interest for the selective reduction of nitrogen oxides by ammonia, and selective oxidation of different hydrocarbons, such as xylenes, olefines and alkanes. Combination analytical techniques used to probe local structural changes at the molecular level, include EXAFS (Extended X-Ray Absorption Fine Structure) spectroscopy utilizing synchrotron radiation, in situ FT-IR coupled to thermodesorption/MS, UV-NIR, and CCD Raman.

Bein, T.

1993-03-01

293

Characterization of active sites in zeolite catalysts  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Atomic-level details of the interaction of adsorbed molecules with active sites in catalysts are urgently needed to facilitate development of more effective and/or environmentally benign catalysts. To this end the authors have carried out neutron scattering studies combined with theoretical calculations of the dynamics of small molecules inside the cavities of zeolite catalysts. The authors have developed the use of H{sub 2} as a probe of adsorption sites by observing the hindered rotations of the adsorbed H{sub 2} molecule, and they were able to show that an area near the four-rings is the most likely adsorption site for H{sub 2} in zeolite A while adsorption of H{sub 2} near cations located on six-ring sites decreases in strength as Ni {approximately} Co > Ca > Zn {approximately} Na. Vibrational and rotational motions of ethylene and cyclopropane adsorption complexes were used as a measure for zeolite-adsorbate interactions. Preliminary studies of the binding of water, ammonia, and methylamines were carried out in a number of related guest-host materials.

Eckert, J. [Los Alamos National Lab., NM (United States); Bug, A. [Swarthmore Coll., PA (United States); Nicol, J.M. [MOLTECH (United States)] [and others

1997-11-01

294

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

295

Copper allergy from dental copper amalgam?  

PubMed

A 65-year-old female was investigated due to a gradually increasing greenish colour change of her plastic dental splint, which she used to prevent teeth grinding when sleeping. Furthermore, she had noted a greenish/bluish colour change on the back of her black gloves, which she used to wipe her tears away while walking outdoors. The investigation revealed that the patient had a contact allergy to copper, which is very rare. She had, however, had no occupational exposure to copper. The contact allergy may be caused by long-term exposure of the oral mucosa to copper from copper-rich amalgam fillings, which were frequently used in childhood dentistry up to the 1960s in Sweden. The deposition of a copper-containing coating on the dental splint may be caused by a raised copper intake from drinking water, increasing the copper excretion in saliva, in combination with release of copper due to electrochemical corrosion of dental amalgam. The greenish colour change of the surface of the splint is probably caused by deposition of a mixture of copper compounds, e.g. copper carbonates. Analysis by the X-ray diffraction technique indicates that the dominant component is copper oxide (Cu2O and CuO). The corresponding greenish/bluish discoloration observed on the back of the patient's gloves may be caused by increased copper excretion in tears. PMID:12083714

Gerhardsson, Lars; Björkner, Bert; Karlsteen, Magnus; Schütz, Andrejs

2002-05-01

296

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

297

Copper(I)-catalyzed three component reaction of sulfonyl azide, alkyne, and nitrone cycloaddition/rearrangement cascades: a novel one-step synthesis of imidazolidin-4-ones.  

PubMed

A novel one-pot azide-alkyne/ketenimine-nitrone cycloaddition sequence that is induced by copper(I) and allows the transformation of sulfonyl azides, alkynes, and nitrones to highly substituted imidazolidin-4-ones is described. The corresponding heterogeneous version utilizing Cu(I)-modified zeolites as recyclable heterogeneous catalysts shows marginally improved yield and diastereoselectivity. PMID:21992587

Namitharan, Kayambu; Pitchumani, Kasi

2011-11-01

298

Vitrification of copper flotation waste.  

PubMed

The vitrification of an hazardous iron-rich waste (W), arising from slag flotation of copper production, was studied. Two glasses, containing 30wt% W were melted for 30min at 1400 degrees C. The first batch, labeled WSZ, was obtained by mixing W, blast furnace slag (S) and zeolite tuff (Z), whereas the second, labeled WG, was prepared by mixing W, glass cullet (G), sand and limestone. The glass frits showed high chemical durability, measured by the TCLP test. The crystallization of the glasses was evaluated by DTA. The crystal phases formed were identified by XRD resulting to be pyroxene and wollastonite solid solutions, magnetite and hematite. The morphology of the glass-ceramics was observed by optical and scanning electron microscopy. WSZ composition showed a high rate of bulk crystallization and resulted to be suitable for producing glass-ceramics by a short crystallization heat-treatment. WG composition showed a low crystallization rate and good sinterability; glass-ceramics were obtained by sinter-crystallization of the glass frit. PMID:17064848

Karamanov, Alexander; Aloisi, Mirko; Pelino, Mario

2007-02-01

299

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

2000-01-01

300

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

2001-01-01

301

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

1999-01-01

302

Zeolites are effective ROS-scavengers in vitro  

Microsoft Academic Search

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

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

2011-01-01

303

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

304

Effect of different glasses in glass bonded zeolite.  

National Technical Information Service (NTIS)

A mineral waste form has been developed for chloride waste salt generated during the pyrochemical treatment of spent nuclear fuel. The waste form consists of salt-occluded zeolite powders bound within a glass matrix. The zeolite contains the salt and immo...

M. A. Lewis J. P. Ackerman S. Verma

1995-01-01

305

Spatially controlled channel entrances functionalization of zeolites L.  

PubMed

The spatially controlled channel entrances functionalization of disk shaped zeolite L crystals is described. Fluorescent dye or bioactive molecules are immobilized at one end of the channels of zeolite crystals and subsequently the other side of the crystals is derivatized with magnetic iron oxide nanoparticles. The asymmetrically functionalized crystals were used for the control of the movement of bacteria in solution. PMID:24510774

Kehr, Nermin Seda; Ergün, Bahar; Lülf, Henning; De Cola, Luisa

2014-05-28

306

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

307

Catalytic cracking of large molecules over hierarchical zeolites.  

PubMed

A hierarchical zeolite catalyst was synthesized by transforming the skeletons of a bimodal pore silica gel into a zeolite through a steam-assisted conversion method, and shows high catalytic activity and a long catalyst lifetime for catalytic cracking of large molecules. PMID:16609799

Lei, Qian; Zhao, Tianbo; Li, Fengyan; Zhang, Lingling; Wang, Yue

2006-04-28

308

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

309

Natural zeolites for oilsands bitumen cracking: Structure and acidity  

Microsoft Academic Search

Clay minerals are well known for their ability to breakdown heavy oils by catalytic cracking, but not much is known of the potential of natural zeolites for oilsands bitumen cracking. Our previous work shows that natural zeolites can effectively crack oilsands bitumen into lighter, less viscous products, while producing fewer residues than analogous thermal cracking reactions. In this follow up

Abu S. M. Junaid; Moshfiqur Rahman; Haiyan Yin; William C. McCaffrey; Steven M. Kuznicki

2011-01-01

310

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

311

The concept of “capacity” in zeolite ion-exchange systems  

Microsoft Academic Search

In the present paper a study is conducted in order to distinguish the several types of capacity used in the literature on zeolite ion-exchange systems, to verify the use of each capacity type, and to analyze the several experimental methods used for capacity determination. Although the study is focused on zeolite clinoptilolite as a characteristic paradigm, its theoretical approaches and

Vassilis J. Inglezakis

2005-01-01

312

Natural zeolites and their ion exchange behavior towards chromium  

Microsoft Academic Search

In this work studies have been performed which demonstrate that trivalent chromium cations may be retained by naturally occuring zeolites. The experimental work perfomed on the natural zeolite clinoptilolite, which is found in abudant quantities in Greece, showed that the ion exchange process is quite rapid and high quantities of chromium ions are removed from the aqueous solutions in a

M. Loizidou; K. J. Haralambous; A. Loukatos; D. Dimitrakopoulou

1992-01-01

313

The adsorption of SOâ by zeolites synthesized from fly ash  

Microsoft Academic Search

Zeolites X, Y, and Na-Pl (90 C) and analcime and sodalite (150 C) were synthesized from Class F fly ash using 3 M sodium hydroxide solutions and autogenous pressures. The partially zeolitized fly ashes were dried overnight in air at room temperature and then characterized using X-ray diffraction and SEM. On occasion, a few samples were dried to constant weight

Anand Srinivasan; Michael W. Grutzeck

1999-01-01

314

Ion exchange in a zeolite-molten chloride system  

SciTech Connect

Electrometallurgical treatment of spent nuclear fuel results in a secondary waste stream of radioactive fission products dissolved in chloride salt. Disposal plans include a waste form that can incorporate chloride forms featuring one or more zeolites consolidated with sintered glass. A candidate method for incorporating fission products in the zeolites is passing the contaminated salt over a zeolite column for ion exchange. To date, the molten chloride ion-exchange properties of four zeolites have been investigated for this process: zeolite A, IE95{reg_sign}, clinoptilolite, and mordenite. Of these, zeolite A has been the most promising. Treating zeolite 4A, the sodium form of zeolite A , with the solvent salt for the waste stream-lithium-potassium chloride of eutectic melting composition, is expected to provide a material with favorable ion-exchange properties for the treatment of the waste salt. The authors constructed a pilot-plant system for the ion-exchange column. Initial results indicate that there is a direct relationship between the two operating variable of interest, temperature, and initial sodium concentration. Also, the mass ratio has been about 3--5 to bring the sodium concentration of the effluent below 1 mol%.

Woodman, R.H.; Pereira, C. [Argonne National Lab., IL (United States). Chemical Technology Div.

1997-07-01

315

Separation of Closely Related Systems by Molecular Sieve Zeolites  

Microsoft Academic Search

Molecular sieve zeolites are robust, thermally stable selective absorbents. They are chemically pure crystalline aluminosilicates with up to 50% of their crystal volume available for adsorption. Zeolites are widely used for industrial drying, purification, and separation, as well as catalysts and ion exchangers. They can be synthesized, on a plant scale, from silica (or sodium silicate) and sodium aluminate. The

A. Dyer

1978-01-01

316

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

317

Formation of superacid centers in the structure of zeolite ZSM-5  

NASA Astrophysics Data System (ADS)

The structural changes and acid characteristics of the zeolite ZSM-5 modified with titanium and sulfur were studied. The modifier components were chemically bonded to the zeolite structure. The acid characteristics of zeolite changed and superacid centers appeared. A physicochemical study showed that treatment of zeolite with titanium tetrachloride and sulfuryl chloride did not change its structure and molecular-sieve properties.

Kitaev, L. E.; Kolesnikova, E. E.; Biryukova, E. N.; Kolesnichenko, N. V.; Khadzhiev, S. N.

2013-04-01

318

Influence of zeolites in PDMS membranes. Pervaporation of water\\/alcohol mixtures  

Microsoft Academic Search

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,

Ivo F. J. Vankelecom; Dirk Depre; Stijn De Beukelaer; Jan B. Uytterhoeven

1995-01-01

319

Cracking Activity of Zeolite Y Catalysts Synthesised from a South African Kaolinite.  

National Technical Information Service (NTIS)

The following catalysts were prepared from ceramic microspheres which contained 24% NaY zeolites: rare earth cation exchanged zeolite Y, rare earth-acidic exchanged zeolite Y and ultrastable zeolite Y with or without exchanged rare earth cations. A prelim...

M. G. Howden

1981-01-01

320

Polyaniline\\/zeolite LTA composites and electrical conductivity response towards CO  

Microsoft Academic Search

Electrical conductivity response of polyaniline\\/zeolite composites towards CO is investigated in terms of dopant type, dopant concentration, zeolite LTA content and zeolite pore size. Both MA and HCl doped polyanilines respond with comparable magnitudes towards CO; the latter responses are slightly smaller for the same doping level. Addition of zeolite 4A reduces the electrical conductivity response but improves the sensitivity

C. Chuapradit; L. Ruangchuay Wannatong; D. Chotpattananont; Piyanoot Hiamtup; A. Sirivat; J. Schwank

2005-01-01

321

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

322

Use of high-silica (VK) zeolites for removal of sulfur compounds from gases  

Microsoft Academic Search

It seemed of interest to determine the adsorption capacity of these high-silica zeolites (VK zeolites) and also general-purpose zeolites with respect to carbon oxide sulfide. We tested 12 samples, altogether. The dynamic and equilibrium characteristics of the zeolites were determined with a laboratory setup consisting of a unit for preparation of a gas mixture, an adsorber equipped with an electric

N. P. Moreva; Z. K. Olenina; Yu. P. Yas'yan; A. Yu. Adzhiev

1991-01-01

323

Molecular sieve zeolite for producing hydrogen by pressure variation adsorption technique  

Microsoft Academic Search

In the increase of the hydrogen content of a gas rich in hydrogen by contacting the gas with a zeolite which selectively adsorbs the gases other than hydrogen to leave the non-adsorbed gas enriched in hydrogen, and then desorbing the adsorbed gases from the zeolite, the improvement which comprises employing as said zeolite Ca-zeolite X granulate in which at least

Reiss

1984-01-01

324

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...

325

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

326

Mineral resource of the month: natural and synthetic zeolites  

USGS Publications Warehouse

Robert Virta, mineral commodity specialist for the U.S. Geological Survey, prepared the following information about the zeolite industry. Volcanic rocks containing natural zeolites — hydrated aluminosilicate minerals that contain alkaline and alkaline-earth metals — have been mined worldwide for more than 1,000 years for use as cements and building stone. For centuries, people thought natural zeolites occurred only in small amounts inside cavities of volcanic rock. But in the 1950s and early 1960s, large zeolite deposits were discovered in volcanic tuffs in the western United States and in marine tuffs in Italy and Japan. And since then, similar deposits have been found around the world, from Hungary to Cuba to New Zealand. The discovery of these larger deposits made commercial mining of natural zeolite possible.

Virta, R.

2008-01-01

327

Optical spectroscopy on Se clusters and chains confined in zeolites.  

PubMed

The incorporation of selenium into the supercages of zeolite Y leads to the formation of Se(8) rings and distorted Se chains in a ratio which is influenced by the nature of the zeolitic cations. Here we review Raman (including resonance Raman) and UV/vis absorption spectroscopy results on Se encapsulated into a number of cation-exchanged faujasite zeolites. Both rings and chains give rise to characteristic Raman bands. In particular, low-frequency Raman bands are attributed to localized vibrations in ordered segments of distorted chains. The UV/vis absorption spectra indicate an opening of the band gap of selenium upon confinement in these zeolites. This can be reversed through electronic interaction with zeolite cations. PMID:15007699

Goldbach, A; Saboungi, M-L

2003-09-01

328

Adsorption kinetics and equilibrium of phenol drifts on three zeolites  

NASA Astrophysics Data System (ADS)

In this study, the sorption of phenol drifts was studied by performing batch kinetic sorption experiments. The equilibrium kinetic data was analyzed using the pseudo-second-order kinetic model. Fowler-Guggenheim model gives a perfect fitting with the isotherm data. The influence of porous structure of a zeolite particle on phenol adsorption from aqueous solutions is analyzed and discussed. The adsorption for phenol drifts on zeolite was proved to be an exothermic process. Thus the solubility of the phenolic compound and the pH of the solution play also an important role in adsorption phenomena. The relative affinity of the phenolic compound toward the zeolite was related to the electron donor-acceptor complexes that were formed between the basic sites on the zeolite (oxygen) and hydrogens (acidic site) of the phenols. Finally zeolite seems to be an efficient adsorbent; it can be easily regenerated by methanol leaching.

Koubaissy, Bachar; Toufaily, Joumana; El-Murr, Maya; Jean Daou, T.; Hafez, Hala; Joly, Guy; Magnoux, Patrick; Hamieh, Tayssir

2012-09-01

329

Surface metal ion enhancement of thermally treated zeolites  

SciTech Connect

During the past several years the area of zeolite science has received increasingly intense attention owing to the preparation of new molecular sieves and the availability of modern spectroscopic methods for the study of these materials. The majority of spectroscopic studies of zeolites have focused on measurements of bulk magnetic, electronic, and structural properties, but few surface studies have been reported. Surface-inhomogeneous aluminum and silicon species have recently been reported by Barr and co-workers. In this study the authors have heated metal ion containing zeolites under controlled conditions in order to probe interactions between the zeolite and the metal ion. Here they present preliminary results for Ag/sup +//NaY and Cs/sup +//NaY zeolites studied by X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), and ion scattering spectroscopy (ISS).

Willis, W.S.; Suib, S.L.

1986-09-03

330

Immobilization of radioactive cesium in pyrolytic-carbon-coated zeolite  

SciTech Connect

All waste forms currently being developed for radwaste disposal have difficulty immobilizing cesium. A new waste form was developed to dispose of cesium by loading up to 5 wt% Cs onto zeolite granules. These zeolite particles are then heat-treated and coated with pyrolytic carbon and/or SiC to completely immobilize cesium. The leach rate of cesium from pyrocarbon-coated zeolite is 3 to 4 orders of magnitude less than for other waste forms. The authors propose that cesium be removed from the primary waste stream and loaded onto zeolite granules for subsequent coating. The total waste form (primary waste form plus coated zeolite) would have acceptable leach resistance for all radwaste components and be extremely leach-resistant for cesium. 23 references, 4 figures, 2 tables.

Stinton, D.P.; Lackey, W.J.; Angelini, P.

1983-06-01

331

Interrupted zeolite LTA and ATN-type boron imidazolate frameworks.  

PubMed

Zeolite A (LTA) is of much interest in zeolite family because of its large-scale industrial applications. Making Zeolite A (a typical 4-connected tetrahedral framework material) with a lower connectivity (3-connected) might lead to new open architecture with expanded ring size and enhanced functionality. The first interrupted Zeolite A with 3-connected network has been experimentally realized here by a boron imidazolate (im) framework material (BIF-20) with 3-coordinate BH(mim)(3)(-) building units. Additionally, a new strategy toward the construction of functional microporous metal-organic frameworks with interrupted zeolite-type topologies is presented by both 3-connected boron imidazolate frameworks (BIF-20 and BIF-21). BIF-20 has an unusual tetrahedral framework with both debonded ? and ? cages, and exhibits high H(2) uptake capacity. PMID:21761820

Zhang, Hai-Xia; Wang, Fei; Yang, Hui; Tan, Yan-Xi; Zhang, Jian; Bu, Xianhui

2011-08-10

332

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.

Vernimmen, Jarian; Cool, Pegie

2011-01-01

333

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.

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

2014-01-01

334

Plant copper chaperones.  

PubMed

Copper chaperones, soluble copper-binding proteins, are essential for ensuring proper distribution of copper to cellular compartments and to proteins requiring copper prosthetic groups. They are found in all eukaryotic organisms. Orthologues of the three copper chaperones characterized in yeast, ATX1, CCS and COX17, are present in Arabidopsis thaliana. Plants are faced with unique challenges to maintain metal homoeostasis, and thus their copper chaperones have evolved by diversifying and gaining additional functions. In this paper we present our current knowledge of copper chaperones in A. thaliana based on the information available from the complete sequence of its genome. PMID:12196180

Wintz, H; Vulpe, C

2002-08-01

335

[Copper and copper alloys. Technology updates].  

PubMed

The correlations between copper and copper alloys and human health have been the subject of some recent and extensive scientific researches. The voluntary risks evaluation, which anticipated the EU REACH Directive application, has shown that copper is a "safe" product for human health and for environment. In addition, it could be of great help thanks to its antibacterial properties. Copper tube can contribute in a relevant way to the prevention of water systems pollution by Legionella. Also the spreading of nosocomial infections is significantly contrasted by the use of copper and copper alloys for the production of articles intended for being frequently touched by people. The Environmental Protection Agency of the United States has in fact "registered" as antibacterial over 350 of copper alloys. PMID:23213799

Loconsolo, V; Crespi, M

2012-01-01

336

Radiation-induced silver agglomeration in molecular sieves: A comparison between A and X zeolites  

NASA Astrophysics Data System (ADS)

The stabilization conditions of silver atoms and clusters in hydrated and dehydrated AgNa-A and AgNa-X zeolites ?-irradiated at 77 K have been studied by ESR. It was found that silver agglomeration mechanisms in hydrated A and X zeolites are very similar and are controlled by the migration of silver atoms into the ?-cages. In dehydrated zeolites agglomeration leads to completely different silver clusters in A and X zeolites. Small cationic clusters are stabilized in A zeolites and metallic clusters in X zeolites. Various factors affecting the agglomeration process in A and X zeolites are discussed.

Sad?o, Jaros?aw; Wa¸sowicz, Tomasz; Michalik, Jacek

1995-06-01

337

Probing zeolites with organic molecules: Supercages of X and Y zeolites are superpolar  

SciTech Connect

Supercages of Li{sup +}- and Na{sup +}-exchanged X and Y zeolites are much more polar than even water. The extent of polarity depends on the nature and the number of cations present within a supercage. The polarity of Li{sup +}- and Na{sup +}-exchanged X and Y zeolites decreases in the presence of water. In presence of water the contribution of cations toward polarity is much smaller than water itself. In this study polarity has been monitored with organic probe molecules, Nile red, pyrene 1-carboxaldehyde and coumarin-500. A connection between polarity and electric field within a cage has also been established. Since the supercages are much more polar than all organic solvents, they can be characterized as superpolar. Because of this one may be able to achieve excited-state switching of carbonyl compounds within a zeolite while such may not be possible in organic solvents. The n{pi}*-{pi}{pi}* state switching of acetophenones is easily achieved within a zeolite while such does not occur in polar solvent methanol-ethanol mixture.

Uppili, S.; Thomas, K.J.; Crompton, E.M.; Ramamurthy, V.

2000-01-11

338

Sodium X-type faujasite zeolite decomposition of dimethyl methylphosphonate (DMMP) to methylphosphonate: Nucleophilic zeolite reactions I  

Microsoft Academic Search

Dimethyl methylphosphonate (DMMP), used extensively as a nerve agent simulant, strongly adsorbs in X-type faujasite zeolite and undergoes nucleophilic substitution by the supercage oxygens. Solid state magic angle spinning (MAS) 31P and cross polarization (CP) MAS 13C NMR studies of the zeolite were performed after adsorption of DMMP into it. Methylphosphonate ions and possibly a framework methyl species are formed

Szu-Wei Yang; David C. Doetschman; Jürgen T. Schulte; Justin B. Sambur; Charles W. Kanyi; Jack D. Fox; Chrispin O. Kowenje; Barry R. Jones; Neesha D. Sherma

2006-01-01

339

Preparation of zeolite sheet using a papermaking technique Part II The strength of zeolite sheet and its hygroscopic characteristics  

Microsoft Academic Search

Zeolite has been widely applied to practical processes in various industrial fields as a desiccant, an adsorbent, a molecular sieve, an ion exchanger, a catalyst and so on. It has generally been used in the form of beads or pellets. However, these methods of utilization have some disadvantages such as powdering of the zeolite when particles rub against each other

H. Ichiura; N. Okamura; T. Kitaoka; H. Tanaka

2001-01-01

340

Investigation on the effect of zeolite precursor on the formation process of MCM-41 containing zeolite Y building units  

NASA Astrophysics Data System (ADS)

The formation process of MCM-41 containing zeolite Y building units has been investigated by UV Raman spectroscopy, 29Si and 27Al MAS NMR spectroscopy, X-ray diffraction (XRD), N2 adsorption and electron microscopy (SEM and TEM). It is found that the precursor containing zeolite Y secondary building units promotes the formation of a metastable mesopore structure just after mixing the zeolite precursors with CTAB. In contrast, the low-polymerized aluminosilicates and well-crystallized zeolite crystals cannot be assembled with CTAB at this stage. The result supports that the zeolite secondary building units should promote to the formation of the mesopore wall. This has been ascribed to its high anionic charge density as well as the appropriate multidentate coordination. Lowering down the pH value to 9.3 facilitates the further polymerization of the aluminosilicate species to build up a stable mesoporous phase.

Li, Peng; Xiong, Guang; Liu, Liping; Wang, Longlong

2013-04-01

341

Investigation on the effect of zeolite precursor on the formation process of MCM-41 containing zeolite Y building units.  

PubMed

The formation process of MCM-41 containing zeolite Y building units has been investigated by UV Raman spectroscopy, (29)Si and (27)Al MAS NMR spectroscopy, X-ray diffraction (XRD), N2 adsorption and electron microscopy (SEM and TEM). It is found that the precursor containing zeolite Y secondary building units promotes the formation of a metastable mesopore structure just after mixing the zeolite precursors with CTAB. In contrast, the low-polymerized aluminosilicates and well-crystallized zeolite crystals cannot be assembled with CTAB at this stage. The result supports that the zeolite secondary building units should promote to the formation of the mesopore wall. This has been ascribed to its high anionic charge density as well as the appropriate multidentate coordination. Lowering down the pH value to 9.3 facilitates the further polymerization of the aluminosilicate species to build up a stable mesoporous phase. PMID:23434547

Li, Peng; Xiong, Guang; Liu, Liping; Wang, Longlong

2013-04-15

342

MAS NMR, ESR and TPD studies of Mo\\/HZSM?5 catalysts: evidence for the migration of molybdenum species into the zeolitic channels  

Microsoft Academic Search

NH3?TPD, MAS NMR and ESR spectroscopies were employed to investigate Mo?modified HZSM?5 catalysts prepared by impregnation. It\\u000a was found that the modification of Mo ions results in a pronounced decrease in the intensity of 1H MAS NMR resonance originating from Brønsted acid sites in the zeolites and a distinct splitting of Mo5+ ESR signals, which is attributed to the interaction

Ding Ma; Weiping Zhang; Yuying Shu; Xiumei Liu; Yide Xu; Xinhe Bao

2000-01-01

343

Growth of large zeolite crystals in space  

NASA Technical Reports Server (NTRS)

Synthesis studies performed using close analogs of triethanolamine (TEA) have shown that all three hydroxyl groups and the amine group in this molecule are necessary to provide nucleation suppression. Studies using C-13 nuclear magnetic resonance (NMR) revealed that the hydroxyl ions and the amine group are involved in the formation of an aluminum complex. It was also shown that silicate species fo not interact this way with TEA in an alkaline solution. These results suggest that successful aluminum complexation leads to nucleation in zeolite-A crystallization.

Sacco, A., Jr.; Dixon, A.; Thompson, R.; Scott, G.; Ditr, J.

1988-01-01

344

Synthesis of large zeolite X crystals  

NASA Astrophysics Data System (ADS)

Large crystals of zeolite X with diameters up to 340 ?m have been synthesized from gels with the composition 4.76Na 2O : 1.0Al 2O 3 : 3.5SiO 2 : 454H 2O : 5-8.5TEA. The syntheses were conducted using aqueous slurries of Cab-O-Sil M-5 or Aerosil 200 fumed silica, and sodium aluminate solutions containing triethanolamine made with sodium hydroxide and aluminum wire or sodium aluminate powder.

Warzywoda, Juliusz; Baç, Nurcan; Sacco, Albert

1999-08-01

345

Zeolitic imidazolate framework as formaldehyde gas sensor.  

PubMed

Traditional semiconducting metal oxide-based gas sensors are always limited on low surface areas and high operating temperatures. Considering the high surface area and high stability of zeolitic imidazolate framework (ZIF), ZIF-67 (surface area of 1832.2 m(2) g(-1)) was first employed as a promising formaldehyde gas sensor at a low operating temperature (150 °C), and the gas sensor could detect formaldehyde as low as 5 ppm. This work develops a new promising application approach for porous metal-organic frameworks. PMID:24813234

Chen, Er-Xia; Yang, Hui; Zhang, Jian

2014-06-01

346

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

347

Resonance Raman and photophysical studies of transition metal complexes in solution and entrapped in zeolites. Progress report, August 1, 1991--March 31, 1992  

SciTech Connect

We have obtained convincing evidence for localization of the optical electron on a single-ring fragment of a chelated ``bipyridine-like`` ligand (ie., pyridylpyrazine or 4-Methyl-bipyridine). In addition we have completed studies of Ru(bipyrazine){sub 3}{sup 2+} in aqueous sulfuric acid (0--98% by weight) and find clear evidence for sequential addition of six-protons to the six peripheral nitrogen atoms. Studies of zeolite-entrapped complexes are continuing and a series of homo- and heteroleptic complexes have been prepared and characterized. Finally, the synthesis of zeolite-entrapped metallophthalocyanines has now been developed and the copper and cobalt analogues synthesized. The characterization of these materials is now in progress.

Kincaid, J.R.

1992-03-31

348

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

349

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

350

Distribution of metal and adsorbed guest species in zeolites  

SciTech Connect

Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

Chmelka, B.F.

1989-12-01

351

Copper-phosphorus alloys offer advantages in brazing copper  

Microsoft Academic Search

Copper-phosphorus brazing alloys are used extensively for joining copper, especially refrigeration and air-conditioning copper tubing and electrical conductors. What is the effect of phosphorus when alloyed with copper? The following are some of the major effects: (1) It lowers the melt temperature of copper (a temperature depressant). (2) It increases the fluidity of the copper when in the liquid state.

1996-01-01

352

Gold nanoclusters confined in a supercage of Y zeolite for aerobic oxidation of HMF under mild conditions.  

PubMed

Au nanoclusters with an average size of approximately 1?nm size supported on HY zeolite exhibit a superior catalytic performance for the selective oxidation of 5-hydroxymethyl-2-furfural (HMF) into 2,5-furandicarboxylic acid (FDCA). It achieved >99?% yield of 2,5-furandicarboxylic acid in water under mild conditions (60?°C, 0.3?MPa oxygen), which is much higher than that of Au supported on metal oxides/hydroxide (TiO2 , CeO2 , and Mg(OH)2 ) and channel-type zeolites (ZSM-5 and H-MOR). Detailed characterizations, such as X-ray diffraction, transmission electron microscopy, N2 -physisorption, and H2 -temperature-programmed reduction (TPR), revealed that the Au nanoclusters are well encapsulated in the HY zeolite supercage, which is considered to restrict and avoid further growing of the Au nanoclusters into large particles. The acidic hydroxyl groups of the supercage were proven to be responsible for the formation and stabilization of the gold nanoclusters. Moreover, the interaction between the hydroxyl groups in the supercage and the Au nanoclusters leads to electronic modification of the Au nanoparticles, which is supposed to contribute to the high efficiency in the catalytic oxidation of HMF to FDCA. PMID:23999985

Cai, Jiaying; Ma, Hong; Zhang, Junjie; Song, Qi; Du, Zhongtian; Huang, Yizheng; Xu, Jie

2013-10-11

353

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

354

Electrical Characteristics of Mesoporous Pure-Silica-Zeolite Film  

NASA Astrophysics Data System (ADS)

The dependence of the electrical characteristics of hydrothermally crystallized pure-silica-zeolite films on the water concentration in the precursor was investigated. Zeolite was crystallized in a silica-zeolite composite film after spin-coating the precursor, which was composed of tetraethylorthosilicate, tetrabutylammonium hydroxide, ethylalcohol, and deionized (DI) water, followed by calcinations at 400 °C. The results of Fourier-transform infrared (FT-IR) spectroscopy indicated that the number of Si-OH and O-H bonds decreased with an increase in the water concentration in the precursor. The dielectric constant of the film decreased with an increase in water concentration, while the leakage current increased.

Seo, Toshiki; Yoshino, Takenobu; Cho, Yoshinori; Hata, Nobuhiro; Kikkawa, Takamaro

2007-09-01

355

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

356

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

357

Gallium Zeolites for Light Paraffin Aromatization  

SciTech Connect

The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.

Price, G.L.; Dooley, K.M.

1999-02-10

358

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

359

Copper Doped Polycrystalline Silicon.  

National Technical Information Service (NTIS)

It was discovered, in accordance with the invention, that the presence of copper in polycrystalline silicon solar cells strongly enhances the performance of the cells. It was further discovered that the effect of copper in polycrystalline, silicon solar c...

K. M. Koliwad T. Daud

1979-01-01

360

Copper Crusher Gauge Holder.  

National Technical Information Service (NTIS)

A copper crusher gauge holder for testing internal pressures of cartridges during test firing is provided. The copper crusher gauge holder has a circular aluminum upper plate and a circular aluminum lower plate having a layer of urethane rubber approximat...

E. W. Bowie R. E. Bowen

1997-01-01

361

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

362

Isobutane/2-butene alkylation on ultrastable Y zeolites: Influence of zeolite unit cell size  

SciTech Connect

The alkylation reaction of isobutane with trans-2-butene has been carried out on a series of steam-dealuminated Y zeolites with unit cell sizes ranging from 2.450 to 2.426 nm. A fixed-bed reactor connected to an automatized multiloop sampling system allowed differential product analysis from very short (1 min or less) to longer times on stream. A maximum in the initial 2-butene conversion was found on samples with unit cell sizes between 2.435 and 2.450 nm. However, the TMP/DMH ratio, i.e., the alkylation-to-oligomerization ratio, continuously increased with zeolite unit cell size. The concentration of reactants in the pores, the strength distribution of Bronsted acid sites, and the extent of hydrogen transfer reactions, which in turn depend on the framework Si/Al ratio of a given zeolite, were seen to affect activity and product distribution of the catalysts. Finally, the influence of these factors on the aging characteristics of the samples was also discussed. 17 refs., 7 figs., 4 tabs.

Corma, A.; Martinez, A.; Martinez, C. (Instituto de Tecnologia Quimica, Valencia (Spain))

1994-03-01

363

Copper levels in cervical mucus during normal menstrual cycles.  

PubMed

To establish the pattern of copper levels in cervical mucous, individual samples were taken from 10 normal women (aged 23-46), 2-3 times per week during the cycle. Analysis using a modification of the Stoner and Dasler wet ash microtechnique showed the lowest amounts of copper per 100 mg of dried ash (mean-3.2 mcg) in the ovulatory phase. The highest amount of copper was found in the secretory phase (mean 19.4 mcg). The copper level seemed to vary directly with the level of endogenous progesterone and inversely with the level of endogenous estrogen. No significant correlation between age and amount of copper secreted could be established because of the small size of the study. PMID:4710788

Randic, L; Musacchio, I; Epstein, J A

1973-05-01

364

Separation of Copper-64 from Copper Phthalocyanine.  

National Technical Information Service (NTIS)

The separation of copper-64 from irradiated copper phthalocyanine by Szilard-Chalmers effect is studied. Two methods of separation are used: one of them is based on the dissolution of the irradiated dry compound in concentrated sulfuric acid following its...

R. I. M. Battaglin

1979-01-01

365

Motion of Organic Species Occluded or Sorbed within Zeolites.  

National Technical Information Service (NTIS)

Containment of organic species within microporous materials such as zeolites influences their modes of molecular motion. This manifests itself in a range of ways, including a reduction in the volume that is readily accessible to the molecules by translati...

J. M. Newsam B. G. Silbernagel M. T. Melchior T. O. Brun F. Trouw

1988-01-01

366

Studies of MnS cluster formation in laumontite zeolite  

NASA Astrophysics Data System (ADS)

MnS clusters were prepared by treating laumontite zeolite with 0.1 N aqueous manganese nitrate solutions at 296 K (pH 5.8), using a solid/liquid ratio of 1/50, followed by a sulfidation process with H 2S, at 350 K, during 12 h. XRD and magnetic resonance measurements proved that the clusters are formed inside the zeolite channels. Examination of SEM revealed that no disintegration of zeolite framework had occurred during the synthesis. The 27Al MAS NMR spectra of the zeolite framework showed three main resonances in the 30-60 ppm region, which are attributed to distinct Al species. The NMR spectra indicate that structural changes occurred in the tetrahedral framework during the sulfidation process. EPR measurements performed at room temperature evidenced three different Mn species, which are affected by the sulfidation process. The local field effect is shown to be substantial for semiconductor clusters encapsulated in laumontite.

Iacomi, Felicia; Vasilescu, M.; Simon, S.

2006-09-01

367

Iba of Zeolites Exchanged with Lithium for Co2 Retention  

NASA Astrophysics Data System (ADS)

A great concern on the global climatic change, partially due to industry CO2 expelled to the atmosphere, has motivated the search of new materials able to retain this gas. Clays, perovskites, zeolites and membranes have been utilized to trap the CO2. Zeolites are widely used as molecular sieves in different industrial processes related to gas purification or gas separation. Synthetic zeolites exchanged with lithium were prepared as potential material for CO2 retention. A NRA method using the 7Li(p,?)4He was performed in order to measure the the Li contents. With SEM-EDS the atomic concentrations of elements as C, Na, Si, Al, K, Ca, Fe, etc. were determined. Zeolites were also characterized by XRD.

Andrade, E.; Alfaro, S.; Valenzuela, M. A.; Solis, C.; Zaval, E. P.; Rocha, M. F.; Cruz, J.; Pfeiffer, H.; Bosch, P.; Contreras, C.; Baptiste, J.

2009-03-01

368

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

369

Oligomerization of ethene on zeolite ZSM-5 type catalysts.  

National Technical Information Service (NTIS)

Oligomerization of ethene was performed with zeolite ZSM-5 catalysts. Activity and selectives of the catalysts as a function of reaction temperature in the temperature range 550-750 K were investigated in a microreactor. Some experiments were also perform...

T. Dypvik

1992-01-01

370

TS-1 zeolite microengineered reactors for 1-pentene epoxidation.  

PubMed

A zeolite-based microengineered reactor was fabricated and tested for 1-pentene epoxidation over titanium silicalite-1 (TS-1) catalyst, which has been selectively incorporated within the microreactor channel using a new synthesis procedure. PMID:12123024

Wan, Yu Shan Susanna; Chau, Joseph Lik Hang; Gavriilidis, Asterios; Yeung, King Lun

2002-04-21

371

The efficiency of Jordanian natural zeolite for heavy metals removal  

NASA Astrophysics Data System (ADS)

The capability of Jordanian natural zeolite to remove nickel from aqueous solutions was experimentally investigated using a packed bed column. The zeolite samples were obtained from Jabal AL Aritayn in the northeast of Jordan. The effects of the initial concentration of nickel ( C 0), the packed bed length ( L) and the zeolite grain size ( D p) on the adsorption process were considered. The finding indicated that these parameters named had a significant effect on the removal of nickel by the Jordanian zeolite. The characteristic breakthrough curves of the adsorption process were measured. The Klinkenberg model was adopted to explain the kinetic behavior of the adsorption phenomena, and we attempted to fit the packed bed experimental data to the breakthrough curve. The effective diffusivity was estimated and used to predict breakthrough curves under other adsorption conditions.

Taamneh, Yazan; Al Dwairi, Reyad

2013-03-01

372

Catalytic properties of natural zeolites. I. Conversions of aromatic hydrocarbons  

SciTech Connect

The catalytic properties of activated natural zeolites from Cuba, viz., mordenite and clinoptilolite, in the hydrogenation of benzene, the disproportionation of toluene, the isomerization of xylenes, and the cracking of ethylbenzene have been investigated.

Gonzales, H.A.; Romanovskii, B.V.; Topchieva, K.V.

1983-06-01

373

Summary of radioactive operations for Zeolite Vitrification Demonstration Program  

SciTech Connect

The Zeolite Vitrification Demonstration Program (ZVDP) has successfully vitrified the zeolite used in the Submerged Demineralizer System (SDS) at Three Mile Island (TMI) Unit 2 to a borosilicate glass product. Under the ZVDP, the US Department of Energy authorized the Pacific Northwest Laboratory (PNL) to demonstrate the vitrification process on a full scale by use of the in-can melter process. This program was accomplished in two phases. The first phase developed a glass formulation and demonstrated the vitrification process with nonradioactive materials. The second phase received three radioactive liners from the SDS and vitrified the zeolite contained in each. These studies concluded that emission of melter-generated aerosols is responsible for most radioactive, process-related losses to the off-gas system. Tritium, in the form of water vapor, is the only significant gaseous radioactive effluent generated by the vitrification of TMI zeolite waste.

Bryan, G.H.; Goles, R.W.; Knox, C.A.; Siemens, D.H.

1984-01-01

374

Laser induced copper plating  

Microsoft Academic Search

Argon laser induced plating of copper spots and lines from copper sulfate solutions on glass and phenolic resin paper has been investigated. The substrates had to be precoated with an evaporated copper film. The highest plating rates have been obtained with a small film thickness of 25 nm. Spots with a thickness up to 30 ?m were plated.

A. K. Al-Sufi; H. J. Eichler; J. Salk; H. J. Riedel

1983-01-01

375

On copper peroxide  

NASA Technical Reports Server (NTRS)

The action of hydrogen superoxide on copper salts in alcoholic solutions is studied. The action of hydrogen peroxide on copper hydroxide in alcoholic suspensions, and the action of ethereal hydrogen peroxide on copper hydroxide are discussed. It is concluded that using the procedure proposed excludes almost entirely the harmful effect of hydrolysis.

Moser, L.

1988-01-01

376

Copper: Technology & Standards  

NSDL National Science Digital Library

This article explains modern copper mining, ore extraction, and casting processes and details innovative copper products, major markets, service activities, and the future of copper in industry and everyday life. It was published in the November 1998 issue of the online magazine Innovations.

Cohen, Art; Association, Copper D.

377

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

378

Zeolites in the Cascade Range of northern Oregon  

Microsoft Academic Search

Twenty-three zeolite minerals were identified during secondary mineralogy studies of late Tertiary volcanic rock outcrop samples and\\/or late Tertiary to Quaternary geothermal drill-hole specimens in three areas of the Oregon Cascade Range (near Mount Hood, the Breiten bush-Austin Hot Springs area, and Newberry volcano). The Neogene to Holocene volcanic rocks contain euhedral to subhedral zeolite crystals in open spaces of

1997-01-01

379

The role of zeolites in wastewater treatment of printing inks  

Microsoft Academic Search

The adsorption of residual organic pollutants from flocculated printing ink wastewater onto several synthetic zeolites was investigated as a finishing method for additional reduction of TOC. The nonselective removal of total organic content was studied.The amount of adsorbed organics was largest for ZSM-5 and NH4-Beta while the other zeolites studied showed lower efficiency, suggesting that adsorption is independent of pore

D Vujevi?; S Papi?

2004-01-01

380

Dielectric Properties of Electrorheological Fluids Containing Zeolite Particles  

Microsoft Academic Search

Relationships between electrorheological (ER) effects and dielectric properties of suspensions are investigated from measurements of ER and dielectric properties of suspensions containing particles of type A zeolite such as 3A, 4A and 5A. In each suspension containing zeolite 3A or 4A particles, the ER effect is recognized, i.e., an increase in the apparent viscosity is observed when an electric field

Keishi Negita; Yasuhiko Ohsawa

1995-01-01

381

Influence of A-type Zeolite on Methane Hydrate Formation  

Microsoft Academic Search

The porous medium has an important effect on hydrate formation. In this paper, the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system. The results show that A-type zeolite can influence methane hydrate formation. At the temperature of 273.5 K and pressure of 8.3

Xiaoya ZANG; Jianwei DU; Deqing LIANG; Shuanshi FAN; Cuiping TANG

2009-01-01

382

Role of HY Zeolite Mesopores in Hydrocracking of Heavy Oils  

Microsoft Academic Search

Two kinds of NiMo\\/HY catalysts, with and without mesopores, were prepared starting from two NaY zeolites with different Si\\/Al ratios. Both catalysts possessed similar properties arising from micropores because the catalysts had similar zeolitic framework structures. For both catalysts, most of the NiMo sulfides were dispersed inside the micropores. The remaining NiMo sulfides, being relatively large particles (3–10 nm), were

Koichi Sato; Yoichi Nishimura; Kosaku Honna; Nobuyuki Matsubayashi; Hiromichi Shimada

2001-01-01

383

Density functional theory studies of zeolite structure, acidity, and reactivity  

Microsoft Academic Search

Our recent application of quantum mechanical methods to the study of heterogeneous catalysis in zeolites is reviewed. We show\\u000a that density functional theory (DFT) is a powerful means by which zeolite structure, acidity, and reactivity can be elucidated.\\u000a The relative accuracy of DFT is comparable to that of traditional ab initio molecular orbital methods. However, the computational\\u000a requirements of DFT

J. B. Nicholas

1997-01-01

384

Adsorption of methane, ethane and ethylene on molecular sieve zeolites  

Microsoft Academic Search

Adsorption of pure methane, ethane and ethylene on molecular sieve zeolites was examined via the gas chromatographic method to determine the potential for the separation of ethylene from light hydrocarbons. The molecular sieves chosen for the study were H-mordenite and 13X, CaX, 4A and 5A zeolites. Henry's law constants were determined over a variety of temperature ranges between 233 and

R. W. Triebe; F. H. Tezel; K. C. Khulbe

1996-01-01

385

Synthesis and characterization of cobalt modified LTL-type zeolite  

Microsoft Academic Search

Cobalt modified LTL-type zeolite (K-CoL) was hydrothermally synthesized, partially substituting framework aluminum for cobalt atoms. The isomorphous substitution of cobalt into the zeolite structure was confirmed by XRD, TGA, UV–VIS, XPS and chemical analyses. Cobalt ions were removed together with K+ following NH4Cl exchange, indicating Co2+ also to be present as balancing or occluded cations into the channels of K-CoL.

Consuelo Montes de C; A??da Luz Villa de P; M. M Ram??rez-Corredores

2000-01-01

386

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

387

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

388

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

389

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

390

Stability of silver cluster in zeolite A and Y catalysts  

NASA Astrophysics Data System (ADS)

Chemical state analysis of silver species in Ag+ exchanged zeolite A and Y catalysts were carried out by means of XAFS and UV-Vis spectroscopies. Order of thermal stability of silver cluster was Ag(50%)-Y > Ag(60%)-A > Ag(100%)-A, which was consistent with the previous 1H NMR study for stability of chemisorbed hydrogen species. The three shell model (Ag-O, Ag-Ag, and Ag-Al/Si) of silver cluster in zeolites was proposed.

Yamamoto, Takashi; Takenaka, Sakae; Tanaka, Tsunehiro; Baba, Toshihide

2009-11-01

391

Ion exchange of ammonium in natural and synthesized zeolites  

Microsoft Academic Search

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

Yifei Wang; Feng Lin; Wenqin Pang

2008-01-01

392

Microwave assisted synthesis of zeolite A from metakaolin  

Microsoft Academic Search

Zeolites are generally synthesized by the hydrothermal reaction of sodium aluminosilicate gels prepared from pure chemicals in alkaline medium using conventional heating systems. In the present study, microwave energy is used as a novel heating tool for the synthesis of zeolite A and metakaolin (Al2O3·2SiO2), a calcined product of kaolin (Al2O3·2SiO2·2H2O) has been taken as a combined source for silica

Sathy Chandrasekhar; P. N. Pramada

2008-01-01

393

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

394

Asymmetric printing of molecules and zeolites on self assembled monolayers  

NASA Astrophysics Data System (ADS)

Microcontact printing (mCP) is used to immobilize dyes and peptides asymmetrically, by a ``peptide coupling'' reaction, on monolayers of zeolite L crystals in the contact area between the stamp and the surface of the monolayer. Chemically patterned surfaces of monolayers of zeolite L crystals are obtained by using patterned stamps with different ink solutions. Additional printing of functionalized nano-objects on SAMs of zeolite L crystals is demonstrated.Microcontact printing (mCP) is used to immobilize dyes and peptides asymmetrically, by a ``peptide coupling'' reaction, on monolayers of zeolite L crystals in the contact area between the stamp and the surface of the monolayer. Chemically patterned surfaces of monolayers of zeolite L crystals are obtained by using patterned stamps with different ink solutions. Additional printing of functionalized nano-objects on SAMs of zeolite L crystals is demonstrated. Electronic supplementary information (ESI) available: Details of XPS spectra are given. See DOI: 10.1039/b9nr00285e

Kehr, Nermin Seda; Schäfer, Andreas; Ravoo, Bart Jan; de Cola, Luisa

2010-04-01

395

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

396

Role of ammonium fluoride in crystallization process of beta zeolite  

NASA Astrophysics Data System (ADS)

The addition of Na + cations to the starting gel prepared using NH 4F significantly prolonged the crystallization time of beta zeolite. However, in the case of pure silica beta zeolite an addition of more NH 4F reduced the crystallization time by one-half. From 29Si MAS NMR measurements, the signal attributed to pentacoordinated silicon was found to be more pronounced for pure silica beta zeolite in the presence of Na + cations even in the solid phase with low crystallinity, as compared to that in the absence of Na + cations. Considering the results of theoretical calculation, because of more energetically stable state of Na +[SiO 4/2F] - species, it could be presumed that Na +[SiO 4/2F] - species might exist in pure silica beta zeolite. Furthermore, as confirmed by 19F MAS NMR measurements tetraethylammonium fluoride (TEAF) species were enclathrated intact in solid phase during the initial crystallization stage. This suggests that TEAF species are required for the formation of beta zeolite framework, in other words, as "SDA" which conditions the formation of kinetically favored phase, i.e., beta zeolite. Moreover, since part of TEA + cations is replaced by sodium cations, forming Na +[SiO 4/2F] - species, the amount of TEA +[SiO 4/2F] - species involved in either nucleation or crystal growth decreases and thus the crystallization time becomes longer.

Jon, Hery; Oumi, Yasunori; Itabashi, Keiji; Sano, Tsuneji

2007-09-01

397

Moderate-temperature zeolitic alteration in a cooling pyroclastic deposit  

USGS Publications Warehouse

The locally zeolitized Topopah Spring Member of the Paintbrush Tuff (13 Myr.), Yucca Mountain, Nevada, U.S.A., is part of a thick sequence of zeolitized pyroclastic units. Most of the zeolitized units are nonwelded tuffs that were altered during low-temperature diagenesis, but the distribution and textural setting of zeolite (heulandite-clinoptilolite) and smectite in the densely welded Topopah Spring tuff suggest that these hydrous minerals formed while the tuff was still cooling after pyroclastic emplacement and welding. The hydrous minerals are concentrated within a transition zone between devitrified tuff in the central part of the unit and underlying vitrophyre. Movement of liquid and convected heat along fractures from the devitrified tuff to the ritrophyre caused local devitrification and hydrous mineral crystallization. Oxygen isotope geothermometry of cogenetic quartz confirms the nondiagenetic moderate temperature origin of the hydrous minerals at temperatures of ??? 40-100??C, assuming a meteoric water source. The Topopah Spring tuff is under consideration for emplacement of a high-level nuclear waste repository. The natural rock alteration of the cooling pyroclastic deposit may be a good natural analog for repository-induced hydrothermal alteration. As a result of repository thermal loading, temperatures in the Topopah Spring vitrophyre may rise sufficiently to duplicate the inferred temperatures of natural zeolitic alteration. Heated water moving downward from the repository into the vitrophyre may contribute to new zeolitic alteration. ?? 1989.

Levy, S. S.; O'Neil, J. R.

1989-01-01

398

An analysis of commerical zeolite catalysts by multinuclear NMR  

SciTech Connect

This work involves studying two commercial hydrocracking catalysts by solid state multinuclear NMR silicon 29 and aluminum 27 with the goal of developing a method of determining the fraction zeolite in the catalysts. The zeolite fraction is known to be one of the faujasite zeolites type X or Y. The clay matrix of the catalyst is assumed to be kaolinite. Fresh, air-exposed commercial hydrocracking catalysts were provided by Phillips Petroleum. Sample 33351-86 was known to be a physical mixture of a Y zeolite and a clay matrix. The other catalyst, 33351-20, was composed of a faujasite zeolite grown within a clay matrix. Both were suspected of being about 20 wt % zeolite. Nothing is known about the state of pretreatment or cation exchange. A portion of each catalyst was calcined in a porcelain crucible in air at 500{degree}C for two hours with a hour heating ramp preceding and a two hour cooling ramp following calcination. 64 refs., 21 figs., 8 tabs.

Flanagan, L.

1990-09-21

399

Characteristics of copper ion exchanged mordenite catalyst deactivated by HCl for the reduction of NO x with NH 3  

Microsoft Academic Search

The deactivation characteristics of copper ion exchanged mordenite type zeolite catalyst (CuHM) by HCl for the reduction of NOx, particularly from an incinerator with NH3, have been investigated over a fixed bed flow reactor system. X-ray absorption near edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), synchrotron radiation X-ray diffraction (SR-XRD), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption

Jin Woo Choung; In-Sik Nam

2006-01-01

400

Modified Copper Soap Solvent Extraction Method for Measuring Free Fatty Acids in Milk  

Microsoft Academic Search

A modified copper soap method was developed to provide a sensitive, rapid method for determining the free fatty acids in milk and estimating the intensity of lipolyzed flavor. The modification is simpler and more rapid than the original copper soap method. Only a small sample (.5 ml) of milk is needed for this colori- metric test, so it would be

W. F. Shipe; G. F. Senyk; K. B. Fountain

1980-01-01

401

"A Novel Synthesis of Zeolite W..."  

SciTech Connect

Zeolite W has been synthesized using organometallic silicon and aluminum precursors in two hydrothermal systems: organocation containing and organocation-free. The reaction using the organocation yielded a fully crystalline, relatively uniform crystal size product, with no organic molecules occluded in the pores. In contrast, the product obtained from an identical reaction, except for the absence of the organocation, contained amorphous as well as crystalline material and the crystalline phase showed a large diversity of both crystal size and morphology. The use of organometallic precursors, either with or without an organocation, allows for the crystallization of the MER framework at much lower 0H/Si02 and (K+ Na - Al)/Si ratios than is typical of inorganic systems. The reaction products were characterized by XRD, SEM, EDS, and thermal analyses.

Nenoff, Tina M.; Thoma, Steven G.

1999-05-07

402

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 50nm 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 (314mg/g) compared to the micro-zeolite A (266mg/g), even if the mesoporous shell thickness of the nano-zeolite A@SiO2 composites is less (20nm) than that of micro-zeolite A@SiO2 (50nm). Both of these values are significantly larger than the pristine zeolite A (nano-zeolite A; 151mg/g and micro-zeolite A; 146mg/g). PMID:24910060

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

2014-08-15

403

Pervaporation study of aqueous ethanol solution through zeolite-incorporated multilayer poly(vinyl alcohol) membranes: Effect of zeolites  

Microsoft Academic Search

In this study, a series of three-layer zeolite-embedded poly(vinyl alcohol) (PVA) composite membranes have been successfully fabricated with a casting machine. Zeolites, examined with a loading of 20wt%, include 3A, 4A, 5A, NaX, NaY, silicalite and beta. These hydrophilic composite membranes have been evaluated in the dehydration of ethanol aqueous solution by means of pervaporation. The unfilled PVA membrane is

Zhen Huang; Huai-min Guan; Wee lee Tan; Xiang-Yi Qiao; Santi Kulprathipanja

2006-01-01

404

Zeolite/Water: A New Working Pair for Heat Pumps and Heat Stores.  

National Technical Information Service (NTIS)

In comparison with conventional absorption heat pump processes the solid and porous zeolite adsorber permits a simpler and a more advantageous procedure. The operation of a zeolite adsorption cycle is illustrated in Figure 1. The entire system consists of...

P. K. Maier-Laxhuber

1984-01-01

405

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

406

Mesostructured Zeolitic Materials, and Methods of Making and Using the Same.  

National Technical Information Service (NTIS)

One aspect of the present invention relates to mesostructured zeolites. The invention also relates to a method of preparing mesostructured zeolites, as well as using them as cracking catalysts for organic compounds and degradation catalysts for polymers.

J. Y. Ying J. G. Martinez

2004-01-01

407

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

408

Zeta potential measurements of zeolite Y: Application in homogeneous deposition of particle coatings  

Microsoft Academic Search

Zeolite membranes are typically grown from thin coatings of sub-?m size zeolite particles on porous supports. The particles have the function of seeds in forming a dense zeolite membrane by a secondary growth process. This study focuses on how seed layer coatings can be optimally produced, crack- and agglomerate-free, by dip coating from stable dispersions of nano-crystalline zeolite Y. Surface

Tatsiana Kuzniatsova; Yanghee Kim; Krenar Shqau; Prabir K. Dutta; Henk Verweij

2007-01-01

409

Sorption and desorption of ammonium by zeolite: Batch and column studies  

Microsoft Academic Search

The major objective of this research was to investigate the efficiency of zeolite in the removal of NH4-N from swine wastewater and desorption of the sorbed NH4-N from the zeolite saturated with N. Sorption experiments were conducted on the sorbents, zeolites I, II and III. Zeolites II and III which are natural and unmodified, showed better sorption (4400–4500 mg kg

Johnsely S. Cyrus; G. B. Reddy

2011-01-01

410

PENGARUH KANDUNGAN Ca PADA CaO-ZEOLIT TERHADAP KEMAMPUAN ADSORPSI NITROGEN  

Microsoft Academic Search

In industry, Ca zeolite is used as nitrogen selective adsorbent with the use of PSA (Pressure Swing Adsorption)\\/VSA (Vacuum Swing Adsorption) methods. Natural zeolite modified to be Cao-zeolite by ion exchange process using Ca(OH)2. Adsorption test was done on CaO-zeolite with different Ca concentration to understand how it's adsorption phenomena on oxygen and nitrogen. Adsorption test has been done for

M. Nasikin; Tania Surya; Utami dan Agustin

411

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

412

Zeolite-filled polyimide membrane containing 2,4,6-triaminopyrimidine  

Microsoft Academic Search

Interfacial void-free Matrimid polyimide (PI) membranes filled with zeolites were prepared by introducing 2,4,6-triaminopyrimidine (TAP). TAP enhanced the contact of zeolite particles with polyimide chains presumably by forming hydrogen bonding between them. The threshold amount of TAP, needed to depress totally the void formation, varied with zeolite type in the order of zeolite 4A?13X

Hyun Hang Yong; Hyun Chae Park; Yong Soo Kang; Jongok Won; Woo Nyun Kim

2001-01-01

413

New vistas in zeolite and molecular sieve catalysis  

SciTech Connect

There is a close connection between the microscopic structures and the macroscopic properties of zeolite catalysts. The ability to control the zeolite properties through synthetic efforts will continue to be of great importance. At present, the control of zeolite properties mainly involves molecular level manipulations of structural features, e.g., pore size and location of active sites. That is to say, the chemical and/or electronic nature of the catalytically active site is not normally controlled. Rather, the three-dimensional structure surrounding this active site is fabricated. In the 1970s and 1980s, catalyst design implied the manipulation of the porous support material to affect the mass and energy transport properties (length scales of 10[sup [minus]2]-10[sup [minus]9] m). Now, with zeolite catalysts, design implies manipulation at the 10[sup [minus]10]-m length scale and involves complementarity between the active site and reactant geometries, i.e., docking of reactants to the active site. Current zeolite-mediated conversions rely on reactant or product shape selectivity (size discrimination between reactants or products, respectively). Future, high-selectivity reactions will proceed with transition-state shape selectivity that attempts to mimic the behavior observed in enzyme- and antibody-catalyzed conversions. It is likely that new zeolite catalysts will require greater complexity in their preparation. Also, they will be able to catalyze a broader spectrum of reaction chemistries, e.g., oxidations. These factors may induce cost factors that are prohibitive for use in the fuel industries. However, new and widespread opportunities exist in the production of bulk and especially specialty chemicals. Four new areas of zeolite and molecular sieve catalysis in which the author has been involved are briefly described. 53 refs., 4 figs., 1 tab.

Davis, M.E. (California Inst. of Technology, Pasadena (United States))

1993-03-01

414

Quantitative Analysis of Water Confined in Ion-Exchanged Zeolites  

NASA Astrophysics Data System (ADS)

Zeolites, which host large quantities of water, are among the most important rock-forming and environmental minerals in the surface and near-surface regions of the Earth. The physical properties and geochemical behavior of water confined in zeolites differs substantially from that of bulk liquid water, and the energectics of confined water exerts a profound influence on the stability and behavior of zeolites in natural and engineered systems. Because the cations and water molecules are both located in the zeolitic channels, changes in cation content can influence the amount and site occupancies of water molecules in zeolites. In order to find out the relationship between the behavior of confined water and cation composition in zeolites, thermogravimetric and calorimetric experiments were conducted on the mordenite (one of the most common zeolites) samples of mixing Na+ and K+. These mordenite solid solutions were generated by binary ion exchange between pure synthetic Na-mordenite (CBV 10A, obtained from Zeolyst International) and chloride solutions containing Na+ and K+ of different equivalent concentration ratios. The results from dehydration and hydration of the mordenite solid solutions show that when the mole fraction of K+ in mordenite increases, the maximum water content of mordenite decreases and the enthalpy of hydration becomes less exothermic. More importantly, both maximum water content and enthalpy of hydration of mordenite are demonstrated to change linearly with mole fraction of K+. Two energetically distinct sets of water molecules have been observed in mordenite: W1 (relatively less energetic) and W2 (relatively high energetic). Thermodynamic analysis on the hydration of W1 and W2 reveals that these two sets of water molecules behave differently when cation composition of mordenite changes. The water content of W2 is independent of cation composition, whereas W1 loses water with when mole fraction of K+ increases; the enthalpy of hydration of W1 appears to be constant, but that of W2 becomes less exothermic with increasing mole fraction of K+.

Wang, J.; Neuhoff, P. S.

2009-12-01

415

Synthesis of mesoporous zeolite single crystals with cheap porogens  

SciTech Connect

Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, {sup 27}Al magic angle spinning nuclear magnetic resonance ({sup 27}Al MAS NMR), temperature-programmed desorption of ammonia (NH{sub 3}-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystal pores are randomly distributed in the whole crystal. {sup 27}Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites. - Graphical abstract: Mesoporous zeolite single crystals were synthesized by using cheap porogens as template. Highlights: > Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals were synthesized. > Soluble starch or sodium carboxymethyl cellulose (CMC) was used as porogens. > The mesoporous zeolites had connected mesopores although closed pores existed. > Higher catalytic activities were obtained.

Tao Haixiang; Li Changlin; Ren Jiawen [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China); Wang Yanqin, E-mail: wangyanqin@ecust.edu.cn [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China); Lu Guanzhong, E-mail: gzhlu@ecust.edu.cn [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China)

2011-07-15

416

Adsorption of aqueous Zn(II) species on synthetic zeolites  

NASA Astrophysics Data System (ADS)

To supply a good quality drinkable water tends to become a strategic task in both developed and under development countries in the world due to the number of potential contamination sources. One of the major problems is derived from the presence of heavy toxic metals like zinc or lead resulting from industrial activities. Zeolites are known as very efficient mineral substrates for fixing aqueous ionic species through their wide range of channels present in the crystalline structure and due to their strong surface reactivity. MicroPIXE coupled with microRBS (3.05 MeV 4He + ions) have been used to quantify the incorporation of zinc within two commercial zeolites containing alkali elements (zeolite X and clinoptilolite) in the concentration range of: 0.0002-0.05 M at neutral pH. At the beginning of the interaction between zeolite and Zn(II) solution, the adsorption process exhibits a direct proportionality between the content of zinc fixed on the mineral substrate and the aqueous concentration up to 0.01 M. Beyond this point a saturation effect seems to occur, indicating the strong decrease of available adsorption sites. Sodium or potassium ions are probably exchanged with Zn(II) ions during this process. The compared behaviour of the two zeolites is then discussed in terms of kinetic effects based on ionic radius values. A co-adsorption test carried on with a 50-50% Zn(II) 0.001 M-Pb(II) 0.001 M solution shows that lead does not occupy the same sites as zinc because the content of zinc fixed on the zeolite sample exactly corresponds to the result obtained with a pure 0.001 M Zn(II) solution. All these data clearly showed that zeolite surface reactivity is greatly influenced by the mineral cage-like structure and particularly the presence of pockets, spaces and channels.

Badillo-Almaraz, Véronica; Trocellier, Patrick; Dávila-Rangel, Ignacio

2003-09-01

417

Effect of hydrophilic defects on water transport in MFI zeolites.  

PubMed

The subnanometer pore structure of zeolites and other microporous materials has been proposed to act as a molecular sieve for various water separation technologies. However, due to the increased interaction between the solid and water in these nanoconfined spaces, it is unclear which type of interface, be it hydrophilic or hydrophobic, offers an advantageous medium for enhancing transport properties. In this work, we probe the role of hydrophilic defects on the transport of water inside the microporous hydrophobic MFI zeolite pore structure via combined sorption and high-pressure infiltration experiments. While the inclusion of defects was observed to increase the amount of water within the zeolite pore network by up to 7 times at the saturation pressure, the diffusivity of this infiltrated water was lowered by up to 2 orders of magnitude in comparison to that of water within the nearly defect-free hydrophobic MFI zeolite. Subsequently, the permeability of water within the more defective MFI zeolite was an order of magnitude lower than that of the nearly defect-free zeolite. The results from these experiments suggest that the intrinsic hydrophobic pore structure of MFI zeolites can facilitate faster water transport due to the decreased attraction between the water and the defect-free surface. While the strong attraction of water to the defects allows for water to infiltrate the porous network at lower pressures, the results suggest that this strong attraction decreases the mobility of the infiltrated water. The insights gained from this study can be utilized to improve the design of future membranes for water desalination and other separation techniques. PMID:24810585

Humplik, Thomas; Raj, Rishi; Maroo, Shalabh C; Laoui, Tahar; Wang, Evelyn N

2014-06-10

418

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...

419

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...

420

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

421

The effect of zeolite on the properties and hydration of blended cements  

Microsoft Academic Search

In this paper the properties and the hydration of cements containing natural zeolite, coming from the Metaxades area, Thrace, Greece, are studied. The experimental part comprises three stages. In the first stage a complete mineralogical characterization of the zeolite was performed. In addition, the pozzolanic reactivity of the zeolite was evaluated on the basis of the Chapelle test. In the

T. Perraki; E. Kontori; S. Tsivilis; G. Kakali

2010-01-01

422

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

423

The Adsorption of Formic Acid on Y Zeolites: An Infrared Absorbance Study.  

National Technical Information Service (NTIS)

The adsorption of formic acid on an ammonium-Y (NH4-Y) zeolite and an ultrastable hydrogen-Y (H-Y) zeolite has been studied with transmission infrared spectroscopy. The formic acid is determined to be chemically adsorbed on both zeolites as bidentate form...

T. M. Duncan R. W. Vaughan

1980-01-01

424

Effects of additives and heat treatment on the pore size distribution in pelletized zeolite Y  

Microsoft Academic Search

Zeolite Y is a crystalline aluminum silicate used as an adsorbent matrix in the purification of proteins. Particle size enlargement is sometimes required and is achieved by compaction of the zeolite powder followed by heat treatment. To maintain a large surface area available for adsorption, additives are used in the pelletizing procedure. Ultrastable zeolite Y (USY) was compacted into pellets

Daniel Klint; Jan-Olov Bovin

1999-01-01

425

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

426

Ion Exchange Behavior of Natural Zeolites in Distilled Water, Hydrochloric Acid, and Ammonium Chloride Solution  

Microsoft Academic Search

This study presents basic research on the use of natural zeolites for the removal of ammonium ions from aqueous solutions. Three natural zeolites from Shimane, Japan, used in this study are shown to contain varying amounts of clinoptilolite and mordenite. The chemical behavior of these natural zeolites was investigated in distilled water, hydrochloric acid, and ammonium chloride solution. The amount

Yujiro Watanabe; Hirohisa Yamada; Hisao Kokusen; Junzo Tanaka; Yusuke Moriyoshi; Yu Komatsu

2003-01-01

427

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

428

A multicomponent transport model for dehydration of organic vapors by zeolite membranes  

Microsoft Academic Search

The permeation of gases and vapors through zeolite membranes is usually described by the adsorption–diffusion model, which is similar to the solution–diffusion model for polymeric membranes. According to this type of model, a permeating component first adsorbs into zeolite micropores and then diffuses through the zeolite pores due to its chemical potential gradient. However, multicomponent transport is complicated by the

A. Salem; A. A. Ghoreyshi; M. Jahanshahi

2006-01-01

429

Fog Simulator System Modification.  

National Technical Information Service (NTIS)

The report deals with the modification of the daytime fog simulator system. In order to improve its effectiveness to realistically simulate actual fog, several changes have been incorporated into the unit. The fog simulator system and the modifications to...

A. Sussman

1973-01-01

430

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

431

Risk assessment for the transportation of radioactive zeolite liners  

SciTech Connect

The risk is estimated for the shipment of radioactive zeolite liners in support of the Zeolite Vitrification Demonstration Program currently underway at Pacific Northwest Laboratory under the sponsorship of the US Department of Energy. This program will establish the feasibility of zeolite vitrification as an effective means of immobilizing high-specific-activity wastes. In this risk assessment, it is assumed that two zeolite liners, each loaded around July 1, 1981 to 60,000 Ci, will be shipped by truck around January 1, 1982. However, to provide a measure of conservatism, each liner is assumed to initially hole 70,000 Ci, with the major radioisotopes as follow: /sup 90/Sr = 3000 Ci, /sup 134/Cs = 7000 Ci, /sup 137/Cs = 60,000 Ci. Should shipment take place with essentially no delay after initial loading (regardless of loading date), the shipment loading would be only 2.7% higher than that for the assumed six-month delay. This would negligibly affect the overall risk. As a result of this risk assessment, it is concluded that the transport of the radioactive zeolite liners from TMI to PNL by truck can be conducted at an insignificant level of risk to the public.

Not Available

1982-01-01

432

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

433

Role of the zeolitic environment in catalytic activation of methanol  

SciTech Connect

One of the most significant industrial applications of zeolites exploits the ability of the microporous aluminosilicate environment to catalyze the methanol to gasoline (MTG) process. The industrial process proceeds at elevated temperatures ({approximately} 700 K) and methanol pressures which correspond to a loading of {approximately} 5--6 methanol molecules per acidic hydroxyl group, which is believed to be the active site. The authors present an extensive study of the initial stages of the methanol to gasoline conversion in the framework of the ab initio molecular dynamics approach. They investigate the effect of different zeolite environments, methanol loading, and temperature and show that, for understanding the initial adsorption and activation of the adsorbed species, all three factors need to be considered simultaneously. The results allow them to develop a simple model for the activation of the methanol molecule, which elucidates the role of both the zeolite framework and the methanol solvent. The zeolite framework plays an active role in methanol protonation. The solvent significantly softens the C-O bond of the methoxonium, rendering it very anharmonic. High mobility of the methoxonium cation, promoted by some zeolite frameworks, prevents it from forming hydrogen bonds with the active sites and the solvent leading to the activation of the methoxonium species. This picture is shown to be consistent with the experimental infrared spectra.

Stich, I. [Angstrom Technology Partnership, Tsukuba, Ibaraki (Japan)] [Angstrom Technology Partnership, Tsukuba, Ibaraki (Japan); [Slovak Technical Univ., Bratislava (Slovakia); Gale, J.D. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Chemistry] [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Chemistry; Terakura, K. [National Inst. for Advanced Interdisciplinary Research, Higashi, Ibaraki (Japan)] [National Inst. for Advanced Interdisciplinary Research, Higashi, Ibaraki (Japan); [Japan Science and Technology Corp., Kawaguchi, Saitama (Japan); Payne, M.C. [Cavendish Lab., Cambridge (United Kingdom)] [Cavendish Lab., Cambridge (United Kingdom)

1999-04-14

434

Influence of cracking of thiols on zeolite life during removal of Sulfur compounds from natural gas by adsorption  

Microsoft Academic Search

This paper studies the kinetics of coke deposition of NaX zeolite as the result of decomposition of ethanethiol and estimates the loss of the adsorption capacity of the zeolite due to coking. The decrease of the adsorption capacity as a function of the coke content (mass %) is shown in NaX zeolite. The zeolites were laboratory samples obtained under various

N. M. Kuzmenko; Y. M. Afasasev; M. I. Budkina; N. E. Gerasimova

1986-01-01

435

Biogenic nanoparticles: copper, copper oxides, copper sulphides, complex copper nanostructures and their applications.  

PubMed

Copper nanoparticles have been the focus of intensive study due to their potential applications in diverse fields including biomedicine, electronics, and optics. Copper-based nanostructured materials have been used in conductive films, lubrification, nanofluids, catalysis, and also as potent antimicrobial agent. The biogenic synthesis of metallic nanostructured nanoparticles is considered to be a green and eco-friendly technology since neither harmful chemicals nor high temperatures are involved in the process. The present review discusses the synthesis of copper nanostructured nanoparticles by bacteria, fungi, and plant extracts, showing that biogenic synthesis is an economically feasible, simple and non-polluting process. Applications for biogenic copper nanoparticles are also discussed. PMID:23690046

Rubilar, Olga; Rai, Mahendra; Tortella, Gonzalo; Diez, Maria Cristina; Seabra, Amedea B; Durán, Nelson

2013-09-01

436

Graphene synthesis and characterization on copper  

NASA Astrophysics Data System (ADS)

Graphene, two dimensional sheet of carbon atoms has recently gained attention as some of its properties are promising for electronics applications e.g. higher mobility that translates to higher operating frequency for devices geared towards radio frequency applications. Excellent optical transmittance combined with its semi metallic behavior makes it an important material for transparent contacts in solar cells. To bring graphene to the production level, synthesis methods are needed for its growth on wafer scale. It has been shown that chemical vapor deposition (CVD) is one of the techniques that can potentially synthesize wafer scale graphene. Recently copper has gained popularity as an important substrate material for graphene growth due to its lower carbon solubility, which allows better control over number of graphene layers. Here we report optimization of graphene growth on copper foils with our home made atmospheric pressure chemical vapor deposition (APCVD) setup. Graphene growth on copper under APCVD was non self-limiting similar to other reports. It was found that apart from growth parameters surface texture plays a very important role in graphene growth. In fact, few layer and bilayer graphene were obtained on the regions where copper surface was not uniform, confirmed by Raman spectroscopy. To improve copper surface texture thin layer of copper film was evaporated by electron beam evaporation before the graphene growth process. After this modification, monolayer graphene was obtained on areas as large as 300 microm x 300 microm confirmed by Raman area maps. Graphene transfer procedure was also optimized so that graphene on metal surface could be transferred to insulating substrate.

Mohsin, Ali

437

Mitigation of copper corrosion and agglomeration in APS process water systems.  

SciTech Connect

Copper corrosion has been observed in process water (PW) systems at the Advanced Photon Source (APS) dating to the early postcommissioning phase of the project. In time, copper corrosion products agglomerated significantly in certain preferred locations. Significant agglomerations (or deposits) can occur in copper cooling passages such as magnet conductors and x-ray absorbers having relatively large length-to-diameter ratios and where heat is removed by water cooling. Such agglomerations also occur at restrictions found in noncopper system components such as valve seats, fixed orifices, pump seal faces, etc. Modifications to the APS process water system that significantly reduce the rate of copper corrosion are discussed. These modifications have not prevented corrosion altogether. Other means used to prevent component clogging and malfunction as a result of current copper corrosion rates are listed.

Dortwegt, R.; Putnam, C.; Swetin, E.

2002-10-10

438

Pressure-induced Hydration in Zeolite Tetranatrolite  

SciTech Connect

The tetranatrolite-paranatrolite transformation has remained a key problem in understanding the paragenesis of zeolites in the natrolite family. It is accepted that when paranatrolite, approximate formula Na{sub 16-x}Ca{sub x}Al{sub 16+x}Si{sub 24-x}O{sub 80}{center_dot}24H{sub 2}O, is removed from an aqueous environment and exposed to the atmosphere, it loses water and transforms to tetranatrolite, Na{sub 16-x}Ca{sub x}Al{sub 16+x}Si{sub 24-x}O{sub 80}{center_dot}nH{sub 2}O (n {le} 24). Here we show that this transformation is not only reversible, but that tetranatrolite exhibits two sequential pressure-induced hydrations leading first to paranatrolite and then to a superhydrated tetranatrolite above 0.2 and 3.0 GPa, respectively. We have previously reported similar behavior for the corresponding system with an ordered Si/Al distribution, i.e., natrolite itself, however the ordered version of paranatrolite exists over a much smaller pressure range. The pressure-induced transformations of natrolite and tetranatrolite thus further supports the supposition that paranatrolite is a distinct mineral species, with a pressure-stability field dependent upon composition.

Lee,Y.; Hriljac, J.; Parise, J.; Vogt, T.

2006-01-01

439

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

440

Highly selective zeolite membranes as explosive preconcentrators.  

PubMed

Highly selective thin zeolite MFI membranes are synthesized on porous stainless steel and ?-alumina supports using a seeded growth method. An ultraviolet (UV) light treatment is employed as a low temperature alternative to remove the organic structure-directing agent (SDA) to avoid membrane cracking. The feasibility of the use of the MFI membranes as an explosive preconcentrator is examined by measuring the permeation of nitrogen (N(2), an air surrogate) and 1,3,5-trimethylbenzene (TMB) (a 2,4,6-trinitrotoluene (TNT) surrogate) in a mixture of N(2) and TMB. High N(2)/TMB selectivity (>10,000) and reasonable N(2) flux (13.5 mmol/m(2)·s) are observed. On the basis of the flux, a hollow fiber array based preconcentrator is proposed and estimated to provide 1000× concentration within about 1 min using a hollow fiber with a 50 ?m internal radius. This high performance explosive preconcentrator may open a new venue for the detection of subppb or lower level of explosives simply in conjunction with conventional explosives detectors. PMID:22830561

Zhao, Jie; Luo, Ting; Zhang, Xiangwen; Lei, Yu; Gong, Ke; Yan, Yushan

2012-08-01

441

Advanced NMR characterization of zeolite catalysts  

NASA Astrophysics Data System (ADS)

The program discussed in this report is a two-year two-phase joint UOP-University of Illinois study of the application of improved high resolution solid state nuclear magnetic resonance (NMR) techniques to the characterization of zeolite catalysts. During the first phase of this program very pure, and in some cases isotopically enriched faujasites will be prepared and studied by magic angle sample spinning NMR (MASS NMR) and variable engine sample spinning NMR (VASS NMR) on 500 and 360 MHz (proton frequency) NMR spectrometers. The NMR techniques that will be emphasized are the measurement and analysis of the (17)O NMR properties, (27)Al NMR intensity quantitation, and (27)Al and (29)Si NMR relaxation rates. During the second phase of this program these NMR techniques will be used to study the effects of impurity concentration, dealumination treatments and cation exchange on the NMR properties of faujasites. The initial emphasis of this program during Phase I is on the preparation and measurement of the NMR properties of (17)O enriched Na-Y faujasties.

Welsh, L. B.

1985-04-01

442

Effect Of Zeolite Structure On The Rotational Motion Of Adsorbed Hydrocarbon  

NASA Astrophysics Data System (ADS)

Effect of host structure on the rotational motion of adsorbed hydrocarbon has been investigated using molecular dynamics (MD) simulation technique. MD simulations have been carried out on propylene sorbed in Na-Y (having spherical cages), and ZSM-5 (consists of interconnecting channel network) zeolites. Librational motion of propylene molecule was found to be present in ZSM-5 zeolite but was absent in case of Na-Y zeolite. While diffusing inside the ZSM-5 zeolite, propylene molecules prefer its orientation along the channel direction while no such orientational ordering is found in Na-Y zeolite.

Sharma, V. K.; Mitra, S.; Chaplot, S. L.; Mukhopadhyay, R.

2010-12-01

443

S-furnace roof modifications at Xstrata Copper, Timmins, Canada  

Microsoft Academic Search

Flat panel coolers in smelter furnace roofs are simpler to hang than traditional roofs as only one suspension system is required.\\u000a Vertical and horizontal installation and operability issues associated with brick-cooler systems and brick supported by coolers\\u000a are eliminated. Flat panel coolers offer a cost-effective alternative to alternating brick and cooler designs. Minor gas leaks\\u000a between panels are relatively easy

Allan Macrae; John Lenz

2006-01-01

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.

Sherman, John D.

1999-01-01

445

Metal-ceramic composite materials from zeolite precursor  

NASA Astrophysics Data System (ADS)

A straightforward technique of synthesis of metal-ceramic composite materials using a zeolite precursor is proposed. The first stage of this technique consists of the transition metal (Fe2+, Co2+, Ni2+ and Cu2+) cation exchange of commercial zeolites. The subsequent stages provide the reduction of these zeolites by thermal treatment under reducing atmosphere and the sintering of the ceramic matrix embedding the metallic particles. The stages of reduction and sintering may be performed according to two different modalities depending on the desired final product. If metal-ceramic composites for structural applications are desired, the stages of reduction and sintering are performed separately. If metal-ceramic composites for electromagnetic applications are desired, the stages of reduction and sintering are combined into a single firing step.

Marocco, Antonello; Dell'Agli, Gianfranco; Esposito, Serena; Pansini, Michele

2012-03-01

446

Synthetic Zeolites and Other Microporous Oxide Molecular Sieves  

NASA Astrophysics Data System (ADS)

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.

Sherman, John D.

1999-03-01

447

Production of tertiary alkyl ether using improved zeolite catalyst  

SciTech Connect

A process is described for reducing the formation of olefinic oligomer by-products and improving tertiary ether selectivity in the production of high octane alkyl tertiary alkyl ether employing acid zeolite beta catalyst particles having alpha value greater than 300, comprising: steaming or hydrothermally treating said zeolite catalyst particles at elevated temperature to provide treated acid zeolite beta catalyst particles having a reduced alpha value of less than 300; and contacting alkanol and a hydrocarbon feed stream rich in iso-olefins with said steamed or hydrothermally treated catalyst particles under iso-olefin etherification conditions sufficient to provide at least 70 weight percent conversion of said iso-olefins, whereby a product containing at least 95 weight percent of said alkyl tertiary alkyl ether is produced while the formation of olefinic oligomer-by-product is not more than 5 weight percent.

Bell, W.K.; Haag, R.O.

1993-07-06

448

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

449

Copper Delivery by Metallochaperone Proteins  

SciTech Connect

Copper is an essential element in all living organisms, serving as a cofactor for many important proteins and enzymes. Metallochaperone proteins deliver copper ions to specific physiological partners by direct protein-protein interactions. The Atx1-like chaperones transfer copper to intracellular copper transporters, and the CCS chaperones shuttle copper to copper,zinc superoxide dismutase. Crystallographic studies of these two copper chaperone families have provided insights into metal binding and target recognition by metallochaperones and have led to detailed molecular models for the copper transfer mechanism.

Rosenzweig, A.C. (NWU)

2010-03-08

450

Improved Electroformed Structural Copper and Copper Alloys  

NASA Technical Reports Server (NTRS)

Electroforming offers a superior means for fabricating internally cooled heat exchangers and structures subjected to thermal environments. Copper is deposited from many such applications because of the good thermal conductivity. It suffers from mediocre yield strength as a structural material and loses mechanical strength at intermediate temperatures. Mechanical properties similar to those of electroformed nickel are desired. Phase 1 examined innovative means to improve deposited copper structural performance. Yield strengths as high as 483 MPa (70 ksi) were obtained with useful ductility while retaining a high level of purity essential to good thermal conductivity. Phase 2 represents a program to explore new additive combinations in copper electrolytes to produce a more fine, equiaxed grain which can be thermally stabilized by other techniques such as alloying in modest degrees and dispersion strengthening. Evaluation of new technology - such as the codeposition of fullerness (diamond-like) particles were made to enhance thermal conductivity in low alloys. A test fire quality tube-bundle engine was fabricated using these copper property improvement concepts to show the superiority of the new coppers and fabrications methods over competitive technologies such as brazing and plasma deposition.

Malone, G. A.; Hudson, W.; Babcock, B.; Edwards, R.

1998-01-01

451

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

452

Maximizing ammonium nitrogen removal from solution using different zeolites.  

PubMed

Zeolite minerals are ideal for removing ammonium nitrogen (NH4(+)-N) from animal wastes, leachates, and industrial effluents. The objectives of this study were to compare NH4+ removal and kinetics among several commercially available zeolites under various conditions and determine if calorimetry could provide information regarding kinetics of NH4+ removal. Ammonium sorption onto potassium (K) saturated zeolites was compared using synthetic vs. natural swine effluent and with either traditional batch-shaken system or a "tea bag" approach in which zeolites were contained in a mesh sack and suspended in a solution of swine effluent. Ammonium sorption was measured at four retention times using a flow-through system, and the resulting heat response was measured using isothermal calorimetry. Ammonium removal was not significantly different in synthetic vs. natural swine effluent. Ammonium removal was lower in batch-stirred compared to batch-shaken systems, suggesting that diffusion between particles was rate-limiting in the former system. Flow-through cells possessing contact times > 100 s displayed greater NH4+ sorption than batch systems, suggesting that maintaining high NH4+ concentration in solution, removal of exchange products, and sufficient reaction time are critical to maximizing NH4+ removal by zeolites. Within 100 s after NH4+ addition, endothermic heat responses indicated that NH4(+)-K+ exchange had peaked; this was followed by significant heat rate reduction for 50 min. This confirmed findings of an initial fast NH4(+)-K+ exchange followed by a slower one and suggests the 100-s period of rapid reaction is an indicator of the minimum flow through retention time required to optimize NH4+ sorption to zeolites used in this study. PMID:20830934

Penn, Chad J; Warren, Jason G; Smith, Savannah

2010-01-01

453

Monodispersed Ultrafine Zeolite Crystal Particles by Microwave Hydrothermal Synthesis  

SciTech Connect

Microwave hydrothermal synthesis of zeolites is reviewed. Monodispersed ultrafine crystal particles of zeolite (Silicalite-1) have been synthesized in batch reactor vessels by microwave irradiation heating of aqueous basic silicate precursor solutions with tetra propyl ammonium hydroxide as the templating molecule. The effects of major process parameters (such as synthesis temperature, microwave heating rate, volume ratio (i.e., the volume of the initial synthesis solution over the total volume of the reactor vessel), and synthesis time on the zeolite particle characteristics are studied using a computer-controlled microwave reactor system that allows real-time monitoring and control of reaction medium temperature. The changes in the morphology, size and crystal structure of the particles are investigated using scanning electron microscope, dynamic light scattering, X-ray diffraction, and BET surface analysis. We have found that the synthesis temperature, volume ratio, and heating rate play a significant role in controlling the particle size, uniformity, and morphology. Microwave processing has generated new morphologies of zeolite particles (i.e., uniform block-shaped particles that contain mixed gel-nanocrystallites and agglomerated crystal particles) that could not be made by a conventional hydrothermal process. At higher synthesis temperature and lower volume ratio, irregular block-shaped particles were produced, whereas increasing the volume ratio promoted the formation of monodispersed single-crystal particles with uniform shape. Our results clearly demonstrate that faster microwave heating is advantageous to enhance the zeolite crystallization kinetics and produces larger-size crystal particles in shorter time. In addition, zeolite crystallization mechanisms, depending on the microwave heating rate, were also discussed.

Hu, Michael Z. [ORNL; Harris, Michael Tyrone [ORNL; Khatri, Lubna [ORNL

2008-01-01

454

Statistical Approach to the Transformation of Fly Ash into Zeolites  

NASA Astrophysics Data System (ADS)

The experimental conversion of F-class fly ash into zeolites is described. The ash, composed mainly of aluminosilicate glass, mullite and quartz, was collected in the Cracow power plant (southern Poland). The experiments involved the heating of fly ash samples in PTFE vessels. Time, temperature and solution composition were the reaction parameters considered in the experiments and in the subsequent modeling. A series of reactions with 0.5, 3 and 5M NaOH solutions (and some with additional 3M NaCl) were carried out at 70°, 100° and 150°C for 12-48 hours under autogenic pressure (not measured) and at a constant ash-to-solution ratio of 33.3 g/l. The following zeolite phases were synthesized: sodalite (SOD structure), hydroxysodalite (SOD), CAN type phases, Na-X (FAU), and NaP1 (GIS). Statistically calculated relationships based on the mineral- and chemical compositions of the reaction products support the conclusion that the type of zeolite phase that crystallizes depends on the concentration of OH- and Cl- in solution and on the temperature of the reaction. The duration of reaction, if on the order of tens of hours, is of less significance. The nature of the zeolite phase that crystalises is controlled by the intensity and selectivity of the substrate dissolution. That dissolution can favour, in sequence, one or other of the components in the substrate, resulting in Si/Al variation in the reaction solutions. Mullite dissolution (decreasing solution Si/Al) characterizes the most advanced reaction stages. The sequence of crystallization of the zeolite phases mirrors the sequential dissolution of substrate components, and the composition of the crystallizing zeolite crystals reflects the changes in the solution Si/Al.

Derkowski, Arkadiusz; Michalik, Marek

2007-01-01

455

Acid-site distribution on Faujasite-type zeolites determined by n-butylamine titration1. Comparison of the use of hammett and arylmethanol indicators on zeolites X  

Microsoft Academic Search

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°C. The butylamine titrations were performed to visible color changes of Hammett indicators. The Hâ acidities were 0 for the sodium X zeolite, and 0.2, 0.98, and 0.75 for the calcium, lanthanum, and hydrogen zeolites,

Dianne Atkinson; Geoffrey Curthoys

1980-01-01

456

The effects of polymer chain rigidification, zeolite pore size and pore blockage on polyethersulfone (PES)-zeolite A mixed matrix membranes  

Microsoft Academic Search

The polyethersulfone (PES)-zeolite 3A, 4A and 5A mixed matrix membranes (MMMs) were fabricated with a modified solution-casting procedure at high temperatures close to the glass transition temperatures (Tg) of polymer materials. The effects of membrane preparation methodology, zeolite loading and pore size of zeolite on the gas separation performance of these mixed matrix membranes were studied. SEM results show the

Yi Li; Tai-Shung Chung; Chun Cao; Santi Kulprathipanja

2005-01-01

457

Experiments with Zeolites at the Secondary School Level: Experience from The Netherlands  

NASA Astrophysics Data System (ADS)

This article describes a number of experiments that involve zeolites and are suitable for secondary-school chemistry laboratories. The experiments have been introduced successfully into secondary schools in The Netherlands. Zeolites are used in enormous quantities as builders (water softeners) in laundry detergents; they account for 15-30 wt % of most laundry detergents currently on the European market. In a series of experiments, students test the hardness of tap water before and after treatment with some zeolite and perform tests with a range of commercial laundry detergents containing zeolites. Zeolites are also used as catalysts in numerous industrial processes; another experiment described here highlights the use of zeolites as recyclable catalysts in an esterification reaction. A duplicate reaction is carried out in parallel, but using the conventional sulfuric acid catalyst instead of the zeolite. This experiment provides a good example of the benefit of a recyclable, heterogeneous catalyst over the conventional homogeneous one that is discarded as waste material.

Coker, Eric N.; Davis, Pamela J.; Kerkstra, Aonne; van Bekkum, Herman

1999-10-01

458

Factors determining the stability of zeolite-containing aluminum hydroxide pseudosols  

SciTech Connect

The stability of zeolite-containing aluminum hydroxide pseudosols decreases with increase of the zeolite content and of the aging time, and depends on the type of hydroxide and zeolite, its cationic form, the conditions of heat treatment and of mechanical dispersion of the zeolite, and the nature and amount of peptizing agent. Depending on the type of aluminum hydroxide used, the stability of zeolite-containing pseudosols varies in the following series: aluminate, made by continuous precipitation > aluminate, made by intermittent precipitation >> sulfate-aluminate, made by intermittent precipitation. The stability of zeolite-containing aluminum hydroxide pseudosols containing zeolite in different cationic forms decreases in the following series: HY > REY > RECaHY >> CaY > RECaNY/sub 4/Y > NH/sub 4/Y > NaY.

Kurchatkina, T.V.; Pavlikhin, B.M.; Ovsyannikov, S.M.; Aleksandrova, I.L.; Baiburskii, V.L.; Ponomareva, S.N.

1988-10-20

459

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

460

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

461

Zeolite catalysis in the synthesis of isobutylene from hydrous ethanol  

NASA Astrophysics Data System (ADS)

This work deals with the synthesis of isobutylene from a hydrous ethanol feedstock over zeolites. The synthesis is accomplished in three steps: (1) low-temperature direct ethanol conversion to ethylene on H-ZSM-5 zeolite, (2) ethylene conversion to butene products over metal-exchanged zeolites, and (3) butene skeletal rearrangement to isobutylene over FER zeolites. The key to understanding and optimizing each synthesis step lies in the ability to control and regulate the zeolite acidity (Bronsted and Lewis)---both strength and number. Therefore, the continuous temperature programmed amine desorption (CTPAD) technique was further developed to simultaneously count the Bronsted acid sites and quantitatively characterize their strength. The adsorption of ethanol, reaction products, amines, coke and ethanol-derived residue (EDR) were monitored gravimetrically using the highly sensitive, novel Tapered Element Oscillating Microreactor (TEOM) apparatus. The TEOM was also used also in conjunction with CTPAD to characterize Bronsted acidity which is a new application for the instrument. For the first synthesis step, a parallel reaction exists which simultaneously produces diethyl ether and ethylene directly over H-ZSM-5. The reaction rates for each pathway were measured directly using a differential reactor operating at low temperatures (<473 K). Water in the ethanol feed enhances the rate of ethylene formation. A mechanism and kinetic expression are proposed for this reaction over H-ZSM-5, with diethyl-ether desorption and ethylene formation as the rate limiting steps. Heat of adsorption values measured from the independent microcalorimetry work reported in the literature are incorporated into the kinetic analysis which reduces the number of regressed parameters. For the remaining synthesis steps, several zeolite structures (ZSM-5, Y, FER) partially exchanged with Pd, Ti, Ni and Au were prepared and tested. It was determined from this screening study that the zeolites containing Pd are the most efficient catalysts for the dimerization reaction. Characterization results from x-ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopy, and CTPAD suggest a stable, Pd species with a low oxidation state as part of the active site in Pd-exchanged zeolites. Isobutylene was present in the C4 fraction at reasonable quantities for most of the catalyst candidates, especially those containing an alkali metal co-cation.

Phillips, Cory Bernard

1999-11-01

462

Ferrimagnetic copper chloride hydroxide  

Microsoft Academic Search

Magnetic properties of copper chloride hydroxide were studied by using a superconducting quantum interference device. The coercivity of this material was more than 10 000 Oe at 2 K, which is the highest observed in the copper compounds. The magnetic susceptibility as a function of temperature revealed ferrimagnetism in the sample.

S G Yang; T Li; B L Xu; Y W Du

2003-01-01

463

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...

464

Refractories for Copper Production  

Microsoft Academic Search

The furnaces used for producing molten copper from concentrates and scrap - flash: smelters, converters, and anode and fire-refining furnaces - present a unique combination of challenges to refractory life. Highly aggressive slags, mechanical stresses, batch operation, and increasingly higher operating temperatures all combine to destroy most refractory materials. Over the past generation, copper producers have adopted refractory materials biased

MARK E. SCHLESINGER

1996-01-01

465

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