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Sample records for exchanged zsm-5 zeolites

  1. Ion exchange in ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Matthews, D.P.; Rees, L.V.C.

    1986-01-01

    The ion exchange properties of Na-ZSM5 have been studied using a number of univalent and divalent cations at 25degC and 65degC. All the univalent cations studied achieved 100 per cent exchange. The thermodynamic affinity sequence Cs > Rb=NH 4 =H 3 O>K>Na>Li was found at both temperatures for a sample with Si/Al=39. Standard enthalpies of exchange ΔH o were calculated using the van't' Hoff isochore and standard entropies of exchange were then calculated from ΔH o and ΔG o . Multivalent cations were unable to achieve 100 per cent exchange. The maximum exchange was found to increase through the series Ca 2+ cations ( 57 Fe enriched) on dehydration and rehydration following sorption and desorption of ethanol. At least 3 sites for Fe 2+ were observed in the dehydrated zeolite. (author)

  2. Biomineralization of hydroxyapatite in silver ion-exchanged nanocrystalline ZSM-5 zeolite using simulated body fluid.

    Science.gov (United States)

    Kaur, Balwinder; Srivastava, Rajendra; Satpati, Biswarup; Kondepudi, Kanthi Kiran; Bishnoi, Mahendra

    2015-11-01

    Silver ion-exchanged nanocrystalline zeolite (Ag-Nano-ZSM-5) and silver ion-exchanged conventional zeolite (Ag-ZSM-5) were synthesized. Zeolites were incubated in simulated body fluid at 310K for different time periods to grow hydroxyapatite in their matrixes. Significant large amount of hydroxyapatite was grown in Ag-Nano-ZSM-5 matrix after incubation in simulated body fluid when compared to Ag-ZSM-5. The resultant material was characterized using X-ray diffraction, N2-adsorption, scanning/transmission electron microscopy, energy dispersive X-ray, and inductively coupled plasma analysis. Mechanical properties such as compressive modulus, compressive strength, and strain at failure of the parent materials were evaluated. Biocompatibility assays suggested that Ag-Nano-ZSM-5 and hydroxyapatite grown in Ag-Nano-ZSM-5 were compatible and did not impose any toxicity to RAW 264.7 cells macrophase and Caco2 cells suggesting considerable potential for biomedical applications such as bone implants. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Incorporation of metals (Pt-Ni-Ru) in the zeolite ZSM-5 through ion exchange competitive: synthesis and characterization

    International Nuclear Information System (INIS)

    Barbosa, A.S.; Rodrigues, M.G.F.

    2012-01-01

    Zeolites are very important materials due to their high specific surface area. Moreover, they are suitable for use as catalyst support. Noble metals supported on zeolites have been widely used as catalysts in the petrochemical industry. This paper was prepared and characterized, a powder aiming its use in heterogeneous catalysis. Support was used as ZSM-5 and the method of incorporation of the metals (Ru-PtNi) was competitive ion exchange. The materials (ZSM-5 and Pt-Ni-Ru/ZSM-5) were characterized by spectrophotometry Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD) and nitrogen physisorption (BET method). Based on the results of X-ray diffraction, it is possible to demonstrate the preservation of the structure of zeolite ZSM-5 after the competitive ion Exchange with metals (Ru-Pt-Ni) and calcination. The dispersion of metals on ZSM-5 did not change the textural characteristics of the zeolite. (author)

  4. Síntese da zeólita ZSM-5 e suas propriedades estruturais após troca iônica com cobre Synthesis of the ZSM-5 zeolite and its structural properties after copper ion-exchange

    Directory of Open Access Journals (Sweden)

    E. L. Foletto

    2000-12-01

    Full Text Available A zeólita ZSM-5 foi sintetizada utilizando sílica "Aerosil-Degussa -- 380 m²/g" como fonte de silício, em substituição ao trisilicato de sódio, que é normalmente utilizado na síntese dessa zeólita. Subseqüentemente, foi incorporado cobre à ZSM-5 através do método convencional de troca iônica. Técnicas de difração de raios X, microscopia eletrônica de varredura, área superficial e análise elementar por absorção atômica foram utilizadas para verificar a formação da zeólita sintetizada e suas propriedades após troca com cobre. Os resultados mostraram que houve a formação da ZSM-5 nas condições de síntese empregadas e que a amostra modificada pelo processo de troca manteve as propriedades da zeólita original.The ZSM-5 zeolite was synthesized using silica "Aerosil-Degussa -- 380 m²/g" as silicon source, in substitution to the sodium trisilicate, which is usually employed in the zeolite synthesis. Subsequently, the copper was incorporated to ZSM-5 by conventional ion-exchange method. X-ray diffraction, scanning electron microscopy, surface area and elemental analysis by atomic absorption have been used to verify ZSM-5 formation and its properties after copper exchange. The results presented ZSM-5 formation in the employed synthesis conditions. The ion-exchanged sample conserved the original ZSM-5 properties.

  5. Infrared spectra and stability of CO and H2O sorption over Ag-exchanged ZSM-5 zeolite: DFT study

    International Nuclear Information System (INIS)

    Jiang Shujun; Huang Shiping; Tu Weixia; Zhu Jiqin

    2009-01-01

    The infrared spectra and stability of CO and H 2 O sorption over Ag-exchanged ZSM-5 zeolite were investigated by using density function theory (DFT). The changes of NBO charge show that the electron transfers from CO molecule to the Ag + cation to form an σ-bond, and it accompanies by the back donation of d-electrons from Ag + cation to the CO (π*) orbital as one and two CO molecules are adsorbed on Ag-ZSM-5. The free energy changes ΔG, -5.55 kcal/mol and 6.52 kcal/mol for one and two CO molecules, illustrate that the Ag + (CO) 2 complex is unstable at the room temperature. The vibration frequency of C-O stretching of one CO molecule bonded to Ag + ion at 2211 cm -1 is in good agreement with the experimental results. The calculated C-O symmetric and antisymmetric stretching frequencies in the Ag + (CO) 2 complex shift to 2231 cm -1 and 2205 cm -1 when the second CO molecule is adsorbed. The calculated C-O stretching frequency in CO-Ag-ZSM-5-H 2 O complex shifts to 2199 cm -1 , the symmetric and antisymmetric O-H stretching frequencies are 3390 cm -1 and 3869 cm -1 , respectively. The Gibbs free energy change (ΔG H 2 O ) is -6.58 kcal/mol as a H 2 O molecule is adsorbed on CO-Ag-ZSM-5 complex at 298 K. The results show that CO-Ag-ZSM-5-H 2 O complex is more stable at room temperature

  6. Zeolite ZSM5 catalysts for abatement of nitrogen oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ganemi, Bager

    1999-07-01

    Airborne pollutants from the combustion of fossil fuels are a global problem. Emission of nitrogen oxides (NO{sub x}) is increasing with the worldwide increase in the use of energy. Atmospheric and photochemical reactions link nitrogen oxides to hydrocarbons and tropospheric ozone. The emission of NO{sub x} has to be tackled urgently in order to limit the harmful effects of anthropogenic activity on the environment. The subject of this thesis is catalytic nitrogen oxide abatement through direct decomposition and reduction by methane over ion-exchanged zeolite ZSM5. The work covers catalytic conversion and surface intermediates, including correlations with the level of exchanged Cu{sup 2+} cations and Ni{sup 2+} or Pd{sup 2+} co-cations. Special attention is given to the aluminium content of the support and changes in structural parameters. It was found that NO{sub x} conversion over cation-exchanged ZSM5 is strongly influenced by the ion-exchange procedure and by the above material parameters. Characterization of Cu-ZSM5 reveals that approximately two molecules of water per Cu{sup 2+} ion desorb at temperatures between 150 and 350 Deg C, in addition to the conventional dehydration at lower temperatures. The desorbed water comes from the decomposition of Cu(OH){sub 2}. Decomposition of hydroxylated copper ions results in the formation Of Cu{sup 2+}-O-Cu{sup 2+} dimers, which are suggested to be the active sites for catalytic decomposition of NO. Acid sites are important for the dispersion of copper ions on the catalyst surface. Acid sites are also important for the interaction between copper species and the zeolite. Increased acidity leads to a stronger interaction between the exchanged cation and the framework, i.e. the exchanged cations become more resistant to mobility. The stronger bond between the exchanged cations and lattice oxygen also prevents dealumination of the catalyst and decreases the thermal expansion at higher temperatures. The temperature of

  7. Characterization structural and morphology ZSM-5 zeolite by hydrothermal synthesis

    International Nuclear Information System (INIS)

    Silva, V.J.; Crispim, A.C.; Queiroz, M.B.; Laborde, H.M.; Rodrigues, M.G.F.; Menezes, R.R.

    2009-01-01

    Solid acids are catalytic materials commonly used in the chemical industry. Among these zeolites are the most important business processes including water treatment, gas separation, and cracking long hydrocarbon chains to produce high octane gasoline. Its synthesis, characterization and applications have been widely studied. The objective this study was to synthesize the ZSM-5 zeolite for future use in separation processes and catalysis. The zeolite ZSM-5 was prepared by hydrothermal synthesis at 170°C, using silica, deionized water and the director of structures (TPABr - tetrapropylammonium bromide). The materials were characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and semiquantitative chemical analysis by X ray fluorescence (XRF). According to the XRD was possible to observe the formation of ZSM-5 zeolite, with peaks intense and well defined. The SEM showed the formation of individual particles, clean, rounded shapes. (author)

  8. Nonlinear upconversion based infrared spectroscopy on ZSM-5 zeolite

    DEFF Research Database (Denmark)

    Kehlet, Louis Martinus; Beato, Pablo; Tidemand-Lichtenberg, Peter

    2017-01-01

    We present a spectroscopic measurement of zeolite ZSM-5 in the mid-IR following the methanol attachment to active sites at 200 °C. The spectra are measured using nonlinear frequency upconversion to the near-IR spectral region.......We present a spectroscopic measurement of zeolite ZSM-5 in the mid-IR following the methanol attachment to active sites at 200 °C. The spectra are measured using nonlinear frequency upconversion to the near-IR spectral region....

  9. Study on the Synthesis and Characterization of Nano Silver Loaded ZSM-5 Zeolite for Bacterial Elimination.

    Science.gov (United States)

    Nam, Le Thi Hoai; Vinh, Tran Quang; Loan, Nguyen Thi Thanh; Nhiem, Nguyen Thi; Trang, Nguyen Thi Thu; Tan, Nguyen Minh; Radnik, Jörg

    2015-09-01

    The synthesis of nano silver coated ZSM-5 zeolite (Ag/ZSM-5) by ion exchange method combined with anaerobic thermal treatment and its bacterial elimination performance were studied. The various Ag content of different samples was analysed by atomic absorption spectroscopy method. The Ag/ZSM-5 sample with 0.251 wt% Ag (denoted as ZAg3) was characterized by using atomic absorption spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and pulsed CO chemisorption methods. The results showed that silver nanoparticles with a small nano-size of 2-3 nm were formed and distributed on the surface of ZSM-5 zeolite with a dispersion value of 59%. The samples denoted as ZAg1, ZAg2, ZAg3, ZAg4 correspond to a Ag content of 0.064; 0.128; 0.251; 0.253 wt% Ag. In the evaluation series, after 10 min of contact time between bacterial and Ag/ZSM-5, over 99% of E.coli (initial concentration was 10(6) cfu/ml) could be eliminated by Ag/ZSM-5 with the Ag content of at least 0.251 wt% (ZAg3). In addition, over 99% of Coliform (initial concentration was 10(5) cfu/ml) could be eliminated by Ag/ZSM-5 with Ag content of at least 0.128 wt% (ZAg2). In a further evaluation series varying the contact time, ZAg3 sample could eliminate over 99% and 100% of Ecoli after 10 min and 60 min, respectively (initial concentrations of both E.coli and Coliform were 10(5) cfu/ml). In addition, it could eliminate 100% of Coliform in only 10 min of contact time.

  10. Characteristics of Heavy Metals Adsorption Cu, Pb and Cd Using Synthetics Zeolite Zsm-5

    OpenAIRE

    Priyadi,; Iskandar,; Suwardi,; Mukti, Rino Rakhmata

    2015-01-01

    It is generally known that zeolite has potential for heavy metal adsorption. The objectives of this study were to synthesize and characterize zeolite ZSM-5 and to figure out the adsorption capacity of zeolite ZSM-5 for heavy metals of Cu2+, Pb2+ and Cd2+. Characterization of zeolite ZSM-5 included some variables i.e. crystal structure (XRD), morphology (SEM), specific surface area and total pore volume (N2 physisorption). Adsorption capacity of zeolite ZSM-5 was analysed using a batch system...

  11. Influence of metal coating methods on the activity of bimetal-containing zeolite catalysts of Co, Pd-ZSM-5 in carbon monoxide oxidation

    Science.gov (United States)

    Oleksenko, L. P.; Lutsenko, L. V.; Yatsimirskii, V. K.

    2011-07-01

    It has been established that catalytic activity in the CO oxidation of bimetal-containing zeolite Co,Pd-systems based on ZSM-5 and obtained via ion exchange and impregnation at different orders of the introduction of metal cations is higher than that of monometal-containing systems Co-ZSM-5 and Pd—ZSM-5. Through TPD of NH3, it was determined that coordination-unsaturated bicationic associates are formed in Co,Pd/ZSM-5 zeolites obtained by ion exchange. It was found that the activity of bimetal-containing systems depends on the relation of the active components.

  12. Adsorption of carbon monoxide on Ag(I)-ZSM-5 zeolite: An ab initio density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Zhenzhen [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Yu Yangxin, E-mail: yangxyu@mail.tsinghua.edu.cn [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Mi Jianguo [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Significant difference in adsorption energy is found for CO adsorbed on different Ag{sup +}-exchange sites. Black-Right-Pointing-Pointer Energetically stable sites in Ag-ZSM-5 are found. Black-Right-Pointing-Pointer Introduction of the two Al atoms to the site of Ag-ZSM-5 results in a reduction of CO adsorption energy. Black-Right-Pointing-Pointer Comparison of CO adsorption energy on the corresponding charge-exchange sites of Ag-ZSM-5 and Cu-ZSM-5 is made. - Abstract: Adsorption of carbon monoxide on different Ag{sup +}-exchange sites of Ag-ZSM-5 zeolite has been investigated using density functional theory. The coordination and local geometry of the Ag{sup +} ion in Ag-ZSM-5 as well as adsorption structures and energies of CO adsorbed on these sites are explored extensively. The structure of Ag{sup +}-exchange sites, location of the Al atom on the T site, and number of the Al atoms contained in the sites are considered in the theoretical calculations. The calculated results show that the Ag-O coordination number of two is strongly preferred before and after CO adsorption. The Ag-O bond lengths are in a broad range of 2.2-2.9 Angstrom-Sign , and the Ag-C bond lengths for CO adsorbed on Ag-ZSM-5 zeolite are calculated to be 2.0-2.2 Angstrom-Sign . Both Ag-O and Ag-C bond lengths for CO-Ag-ZSM-5 complex are longer than those for CO-Cu-ZSM-5 complex. The calculated adsorption energy of CO adsorbed on the I2 sites is between 28.5 and 29.6 kcal/mol, and that on the Z5, Z6, M5 and M6 sites containing one Al atom on the T position is between 11.3 and 18.9 kcal/mol whereas the calculated adsorption energy of CO adsorbed on the M7 site containing one Al atom is 19.9 kcal/mol. The introduction of the two Al atoms to the Ag{sup +}-exchange site results in a reduction of CO adsorption energy. In general, the adsorption energy of CO on Ag-ZSM-5 is lower than that on Cu-ZSM-5. The predicted coordination of the Ag{sup +} ion, bond lengths

  13. Zeolite-zeolite composite composed of Y zeolite and single-crystal-like ZSM-5 zeolite: Fabricated by a process like “big fish swallowing little one”

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Meng; Li, Peng [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Zheng, Jiajun, E-mail: zhengjiajun@tyut.edu.cn [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Yujian [SINOPEC Research Institute of Petroleum Processing, Beijing, 100083 (China); Kong, Qinglan [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Tian, Huiping [SINOPEC Research Institute of Petroleum Processing, Beijing, 100083 (China); Li, Ruifeng, E-mail: rfli@tyut.edu.cn [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China)

    2017-06-15

    Zeolite-zeolite composite composed of Y and ZSM-5 zeolite was prepared using depolymerized Y as partial nutrients for the growth of ZSM-5. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), FT-IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption measurement and Thermogravimetric analysis (TG). Chemical equilibrium at the solution-crystal interface was changed because of the partially depolymerized Y zeolite, the conditions necessary for the growth of ZSM-5 were therefore obtained. ZSM-5 zeolite crystals nucleated and grew on the interface, and Y zeolite crystals were then gradually swallowed by the growing single-crystal-like ZSM-5. - Graphical abstract: Y zeolite crystals in the hydrothermal system were partially depolymerized and an ambience in favor of the formation of ZSM-5 was formed, and ZSM-5 zeolite crystals nucleated and grew up on the external surfaces of Y zeolite crystals. As a consequence, Y zeolite crystals were swallowed by single-crystal-like ZSM-5. - Highlights: • Zeolite composite is composed by Y zeolite and single-crystal-like ZSM-5. • A composite material formed by a process like “big fish swallowing little one”. • Ratio of two zeolites in the as-synthesized sample can be adjusted.

  14. Synthesis of mesoporous Cr/ZSM-5 and W-Cr/ZSM-5 zeolite catalysts for oxidation of unsaturated fatty acid

    Directory of Open Access Journals (Sweden)

    Phan Huy Hoang

    2017-10-01

    Full Text Available The mesoporous Cr/ZSM-5 and W-Cr/ZSM-5 zeolites have been successfully synthesized by loading chromium and tungsten on zeolite support. The metal loaded ZSM-5 catalysts were analyzed by several characterizations such as XRD, SEM-EDS, TEM, and BET. The catalytic activities and recycle efficiency were also investigated by applying catalysts for oxidation of oleic acid. These catalysts exhibited the high catalytic efficiency for cleavage of double bond with the use of H2O2. The oleic conversion of 88.7% and 93.3% could be achieved for Cr/ZSM-5 and W-Cr/ZSM-5 catalyst, respectively. Moreover, the modified ZSM-5 catalysts also demonstrated a long life time and high stability.

  15. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    International Nuclear Information System (INIS)

    Ding, Weiping; Meitzner, George D.; Marler, David O.; Iglesia, Enrique

    2001-01-01

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5

  16. Desilication of ZSM-5 zeolites for mesoporosity development using microwave irradiation

    International Nuclear Information System (INIS)

    Hasan, Zubair; Jun, Jong Won; Kim, Chul-Ung; Jeong, Kwang-Eun; Jeong, Soon-Yong; Jhung, Sung Hwa

    2015-01-01

    Highlights: • Microwaves have beneficial effects on desilication of zeolites. • Produced mesopores with microwaves have narrow pore-size distribution. • Advantages and disadvantages of various desilicating agents were also reported. - Abstract: Mesoporous ZSM-5 zeolite was obtained by desilication in alkaline solutions with microwave (MW) and conventional electric (CE) heating under hydrothermal conditions. Both methods were effective in the production of mesoporous zeolites; however, MW was more efficient than CE as it led to well-defined mesopores with relatively small sizes and a narrow size distribution within a short treatment time. Moreover, the mesoporous ZSM-5 obtained through this method was effective in producing less bulky products from an acid-catalyzed reaction, specifically the butylation of phenol. Finally, various bases were found to have advantages and disadvantages in desilication. NaOH was the most reactive; however, macroporosity could develop easily under a severe condition. Ammonia water was weakly reactive; however, it could be used to precisely control the pore architecture, and no ion exchange is needed for acid catalysis. Organic amines such as ethylenediamine can also be used in desilication

  17. Use of Zeolite ZSM-5 for Loading and Release of 5-Fluorouracil

    Directory of Open Access Journals (Sweden)

    Ruba A. Al-Thawabeia

    2015-01-01

    Full Text Available Samples of zeolite ZSM-5 have been synthesized in both the sodium form (ZSM-5 and the acid activated form (H-ZSM-5. In addition, each of these two forms was prepared in the two molar SiO2/Al2O3 ratios of 169 and 15. All samples of these ZSM-5 derivatives were characterized by X-ray diffraction (XRD, nitrogen adsorption-desorption isotherms, thermal gravimetric analysis (TGA, X-ray fluorescence (XRF, and scanning electron microscopy (SEM. The samples were successfully loaded with the anticancer drug 5-fluorouracil (5-FU with loading capacities varying from 22% (for the sodium form having the lower molar SiO2/Al2O3 ratio of 15, ZSM-5-(15 to 43% (for the corresponding acid form, H-ZSM-5-(15. Percent release of the drug-loaded ZSM-5 samples into simulated body fluid (SBF was measured at pH 7.4 and 37°C. The results showed a slight variation in the % release within the range 84–93%, while the first-order rate constant (k varied from 2.2 h−1 for ZSM-5-(15 to 3.9 h−1 for H-ZSM-5-(15. It was interesting to note that at the higher molar SiO2/Al2O3 ratios of 169, both the sodium form, ZSM-5-(169, and the acid form, H-ZSM-5-(169, exhibit an intermediate efficiency in either % loading (38% or first-order kinetic release constant (k = 2.9 h−1.

  18. Experimental study on desorption characteristics of SAPO-34 and ZSM-5 zeolite

    Science.gov (United States)

    Yuan, Z. X.; Zhang, X.; Wang, W. C.; Du, C. X.; Liu, Z. B.; Chen, Y. C.

    2018-03-01

    The dynamic characteristics of SAPO-34 and ZSM-5 zeolite in the desorption process have been experimentally studied with the gravimetric method. The weight change of the test sample was recorded continually for different conditions of temperature and pressure. The curve of the desorption degree with the temperature and the pressure was obtained and discussed. With the intrinsic different micro-structure, the two zeolites showed distinguished characteristics of the desorption. In contrast to an S-shaped desorption curve of the SAPO-34, the ZSM-5 showed an exponential desorption curve. In comparison, the desorption characteristics of the ZSM-5 were better than that of the SAPO-34 in the temperature range of 40 °C 90 °C. Nevertheless, the effect of the pressure on the desorption degree was stronger for the SAPO-34 than for the ZSM-5. Further analysis revealed that the desorption speed was affected more strongly by the temperature than by the pressure.

  19. Bidimensional ZSM-5 zeolites probed as catalysts for polyethylene cracking

    Czech Academy of Sciences Publication Activity Database

    Peral, A.; Escola, J. M.; Serrano, D. P.; Přech, Jan; Ochoa-Hernández, Cristina; Čejka, Jiří

    2016-01-01

    Roč. 6, č. 8 (2016), s. 2754-2765 ISSN 2044-4753 R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : PILLARED MOLECULAR -SIEVE * NANOCRYSTALLINE ZSM-5 * PROTOZEOLITIC UNITS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.773, year: 2016

  20. Utilization of biomass: Conversion of model compounds to hydrocarbons over zeolite H-ZSM-5

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Holm, Martin Spangsberg

    2011-01-01

    Zeolite catalyzed deoxygenation of small oxygenates present in bio-oil or selected as model compounds was performed under Methanol-to-Hydrocarbons (MTH) like reaction conditions using H-ZSM-5 as the catalyst. Co-feeding of the oxygenates with methanol generally decreases catalyst lifetime due...

  1. Co2+ Ions as Probes of Al Distribution in the Framework of Zeolites. ZSM-5 Study

    Czech Academy of Sciences Publication Activity Database

    Dědeček, Jiří; Kaucký, Dalibor; Wichterlová, Blanka; Gonsiorová, O.

    2002-01-01

    Roč. 4, - (2002), s. 5406-5413 ISSN 1463-9076 R&D Projects: GA MŠk OC D15.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : Al distribution in zeolites * ZSM-5 * Vis spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.838, year: 2002

  2. Transalkylation of ethyl benzene with triethylbenzene over ZSM-5 zeolite catalyst

    KAUST Repository

    Akhtar, M. Naseem; Tukur, Nasiru M.; Al-Yassir, Nabil; Al-Khattaf, Sulaiman; Čejka, Jiří

    2010-01-01

    Transalkylation of 1,3,5-triethylbenzene (TEB) with ethylbenzene (EB) has been studied over ZSM-5 zeolite using a riser simulator reactor with respect to optimizing DEB yield. The reaction temperature was varied from 350 to 500°C with contact time

  3. Deactivation and regeneration of ZSM-5 zeolite in catalytic pyrolysis of plastic wastes

    International Nuclear Information System (INIS)

    Lopez, A.; Marco, I. de; Caballero, B.M.; Adrados, A.; Laresgoiti, M.F.

    2011-01-01

    Highlights: → Pyrolysis transforms plastic wastes in valuable liquids and gases useful as fuels or source of chemicals. → The use of ZSM-5 zeolite in pyrolysis favours the production of gases and of lighter and more aromatic liquids. → ZSM-5 zeolite is almost completely deactivated after one plastics pyrolysis experiment. → ZSM-5 zeolite used in plastic wastes pyrolysis can be regenerated by burning the deposited coke in an air stream. → Regenerated ZSM-5 recovers its activity and produces liquids and gases equivalent to those obtained with fresh catalyst. - Abstract: In this work, a study of the regeneration and reuse of ZSM-5 zeolite in the pyrolysis of a plastic mixture has been carried out in a semi-batch reactor at 440 deg. C. The results have been compared with those obtained with fresh-catalyst and in non-catalytic experiments with the same conditions. The use of fresh catalyst produces a significant change in both the pyrolysis yields and the properties of the liquids and gases obtained. Gases more rich in C3-C4 and H 2 are produced, as well as lower quantities of aromatic liquids if compared with those obtained in thermal decomposition. The authors have proved that after one pyrolysis experiment the zeolite loses quite a lot of its activity, which is reflected in both the yields and the products quality; however, this deactivation was found to be reversible since after regeneration heating at 550 deg. C in oxygen atmosphere, this catalyst recovered its initial activity, generating similar products and in equivalent proportions as those obtained with fresh catalyst.

  4. Thermochemical properties of copper forms of zeolite ZSM5 containing dimethylethylenediamine

    International Nuclear Information System (INIS)

    Cuvanova, S.; Rehakova, M.; Finocchiaro, P.; Pollicino, A.; Bastl, Z.; Nagyova, S.; Fajnor, V.S.

    2007-01-01

    Synthetic zeolite ZSM5 and its copper forms containing N,N-dimethylethylenediamine (dmen) have been investigated by CHN, energy dispersive spectroscopy (EDS) analysis, X-ray powder diffractometry, X-ray photoelectron spectroscopy and continuous waves hydrogen nuclear magnetic resonance (CW 1 H NMR) spectroscopy. Thermal properties have been studied by methods of thermal analysis-TG, DTA and DTG in the temperature range 20-1000 deg. C in air atmosphere. Mass spectroscopy method was used for the study of the released gas products of thermal decomposition. The results of thermal analyses of two zeolitic samples Cu-ZSM5 and Cu(dmen) x ZSM5 (x depends on the mode of preparation) demonstrated their different thermal properties. The main part of the decomposition process of the samples Cu(dmen) x ZSM5 occurs at considerably higher temperatures than the boiling point of dimethylethylenediamine, proving strong bond and irreversibility of dmen-zeolite interaction. According to the results of mass spectroscopy the decomposition process in inert atmosphere is characterized by the development of a large spectrum of products with atomic mass from 18 to 447 atomic mass units as a consequence of the catalytic effect of the silicate surface

  5. Photocatalytic Oxidation of NO over Composites of Titanium Dioxide and Zeolite ZSM-5

    Directory of Open Access Journals (Sweden)

    Akram Tawari

    2016-02-01

    Full Text Available Composites of TiO2 (Hombikat, P25, sol-gel synthesis and zeolite ZSM-5 (nSi/nAl = 55 with mass fractions from 25/75 to 75/25 were prepared by mechanical mixing, solid-state dispersion and sol-gel synthesis. Characterization of the composites by X-ray diffraction (XRD, N2-sorption, scanning electron microscopy (SEM, and UV-Vis spectroscopy show that mechanical mixing and solid-state dispersion lead to comparable textural properties of the composites. A homogeneous distribution and intimate contact of small TiO2 particles on the crystal surface of zeolite ZSM-5 were achieved by sol-gel synthesis. The composites were studied in the photocatalytic oxidation (PCO of NO in a flatbed reactor under continuous flow according to ISO 22197-1. The highest NO conversion of 41% at an NO2 selectivity as low as 19% stable for 24 h on-stream was reached over the TiO2/ZSM-5 composite from sol-gel synthesis with equal amounts of the two components after calcination at 523 K. The higher activity and stability for complete NO oxidation than for pure TiO2 from sol-gel synthesis, Hombikat, or P25 is attributed to the adsorptive properties of the zeolite ZSM-5 in the composite catalyst. Increasing the calcination temperature up to 823 K leads to larger TiO2 particles and a lower photocatalytic activity.

  6. Catalytic conversion of 11C-labeled methanol over Cs-ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Salmi, T.; Murzin, D.Yu.

    2004-01-01

    Reaction mechanism of the conversion of 11 C labeled methanol over basic Cs-ZSM-5 zeolite catalyst was investigated and the reaction products obtained were compared with that of H-ZSM-5 acidic catalyst. The catalytic experiments were carried out by passing 11 C-labeled methanol with He as a carrier gas over Cs-ZSM-5 packed in a micro reactor. After adsorption of the radio methanol, the catalyst was heated up to 330 deg C. The products of the catalytic conversion of the 11 C-labeled methanol were analyzed by radio-gas chromatography (gas chromatograph with thermal conductivity detector on-line coupled with a radioactivity detector). (N.T.)

  7. Adsorption of butyl acetate in air over silver-loaded Y and ZSM-5 zeolites: experimental and modelling studies.

    Science.gov (United States)

    Bhatia, Subhash; Abdullah, Ahmad Zuhairi; Wong, Cheng Teng

    2009-04-15

    Adsorption behaviours of butyl acetate in air have been studied over silver-loaded Y (Si/Al=40) and ZSM-5 (Si/Al=140) zeolites. The silver metal was loaded into the zeolites by ion exchange (IE) and impregnation (IM) methods. The adsorption study was mainly conducted at a gas hourly space velocity (GHSV) of 13,000 h(-1) with the organic concentration of 1000 ppm while the desorption step was carried out at a GHSV of 5000 h(-1). The impregnated silver-loaded adsorbents showed lower uptake capacity and shorter breakthrough time by about 10 min, attributed to changes in the pore characteristics and available surface for adsorption. Silver exchanged Y (AgY(IE)) with lower hydrophobicity showed higher uptake capacity of up to 35%, longer adsorbent service time and easier desorption compared to AgZSM-5(IE). The presence of water vapour in the feed suppressed the butyl acetate adsorption of AgY(IE) by 42% due to the competitive adsorption of water on the surface and the effect was more pronounced at lower GHSV. Conversely, the adsorption capacity of AgZSM-5(IE) was minimally affected, attributed to the higher hydrophobicity of the material. A mathematical model is proposed to simulate the adsorption behaviour of butyl acetate over AgY(IE) and AgZSM-5(IE). The model parameters were successfully evaluated and used to accurately predict the breakthrough curves under various process conditions with root square mean errors of between 0.05 and 0.07.

  8. Photodegradation of Methyl Green by Nickel-Dimethylglyoxime/ZSM-5 Zeolite as a Heterogeneous Catalyst

    Directory of Open Access Journals (Sweden)

    Alireza Nezamzadeh-Ejhieh

    2013-01-01

    Full Text Available Ni-DMG/ZSM-5 zeolite was prepared by ion exchange and complexation procedures. FT-IR, XRD, SEM, TG, and DTG methods were used for characterization of the raw and modified samples. The prepared composite was used as a catalyst in the photodegradation process of an aqueous solution methyl green (MG dye under UV irradiation. The effect of key operating parameters such as catalyst dosage, temperature, the initial concentration of the dye, and pH of the samples was studied on the degradation extent of the dye. UV-Vis spectrophotometric measurements were performed for determination of the decolorization and mineralization extents. The optimal operation parameters were found as follows: , temperature of 60°C, 0.6 g L−1 of the catalyst, and 40 ppm of the dye concentration. The Ni-DMG particles out of zeolite framework did not show significant degradation efficiency. The degradation process obeys the first-order kinetic.

  9. Photoionization and Electron Transfer of Biphenyl within the Channels of Al-ZSM-5 Zeolites.

    Science.gov (United States)

    Gener, Isabelle; Buntinx, Guy; Brémard, Claude

    1999-06-14

    Evidence of the photogenerated long-lived biphenyl radical and a trapped electron in the void space of aluminated nonacidic ZSM-5 zeolites has been obtained from the time-resolved UV/Vis absorption, Raman scattering, and EPR spectra. The restoration of the ground states implicates the existence of long-lived positive holes in the framework. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  10. Highly Oriented Growth of Catalytically Active Zeolite ZSM-5 Films with a Broad Range of Si/Al Ratios

    NARCIS (Netherlands)

    Fu, Donglong|info:eu-repo/dai/nl/412516918; Schmidt, Joel E.|info:eu-repo/dai/nl/413333736; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Chowdhury, Abhishek Dutta|info:eu-repo/dai/nl/412438003; Meirer, Florian; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2017-01-01

    Highly b-oriented zeolite ZSM-5 films are critical for applications in catalysis and separations and may serve as models to study diffusion and catalytic properties in single zeolite channels. However, the introduction of catalytically active Al3+ usually disrupts the orientation of zeolite films.

  11. Influence of the Zeolite ZSM-5 on Catalytic Pyrolysis of Biomass via TG-FTIR

    Directory of Open Access Journals (Sweden)

    Ze Wang

    2015-06-01

    Full Text Available Bio-oil from the pyrolysis of biomass is an important renewable source for liquid fuel. However, the application of bio-oil has been severely restricted due to its high viscosity, acidity, and low heating value. Thus, it has been necessary to upgrade bio-oil for automobile fuel via catalytic deoxygenation reactions. Herein, the effects of the zeolite ZSM-5 on the pyrolysis of four biomass materials (corn cob, corn straw, pine powder, and cellulose were investigated via TG-FTIR (thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer to better understand the working mechanism of ZSM-5. The contents of the products of H2O, CO, CO2, and the C-O, C=O, and OH groups evolved with increasing pyrolytic temperature were monitored by FTIR. It was found that the relative contents of the C-O and C=O groups were decreased under the catalysis of ZSM-5, while the formations of CO, H2O, and the OH containing compounds were promoted. To explain the regulations, reaction routes were speculated and the catalytic conversion mechanisms were deduced.

  12. Hierarchical ZSM-5 Zeolite: Synthesis and Application in Oil Refinery%多级孔ZSM-5分子筛的制备及其在炼油领域中的应用

    Institute of Scientific and Technical Information of China (English)

    郑步梅; 方向晨; 郭蓉; 王振宇

    2017-01-01

    The hierarchical ZSM-5 zeolite integrates the merits of both microporous zeolite and mesoporous materi al.It possesses not only adjustable acidity and high hydrothermal stability,but also excellent diffusivity.Consequently,the hierarchical ZSM-5 zeolite has a wide application prospect in catalytic fields.The research progress of hierarchical ZSM-5 zeolite was reviewed,with the main focus on the synthesis strategies including post-treatment method,hard-templating method and soft-templating method.Meanwhile the applications of hierarchical ZSM-5 zeolite in oil refining field were introduced.Finally,the development trends of hierarchical ZSM-5 are prospected.%多级孔ZSM-5分子筛结合了微孔分子筛可调变的酸性、良好的水热稳定性以及介孔材料优异的传质扩散性能,在催化领域有着广阔的应用前景.我们综述了近年来多级孔ZSM-5分子筛的研究进展,重点概述了多级孔ZSM-5分子筛的不同制备方法,包括后处理法、硬模板法和软模板法等,同时介绍了多级孔ZSM-5分子筛在炼油领域的应用研究,并在上述基础上对多级孔ZSM-5分子筛的研究趋势进行了展望.

  13. Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Lercher, Johannes A. [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Dept. of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 Garching 85748 Germany

    2016-10-06

    Aqueous phase dehydration of 1-propanol over H-ZSM-5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulation of the mimicking aqueous phase H-ZSM-5 zeolite unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol-propanol, the propanol-water complex, and the trimeric propanol-propanol-water are formed at high propanol concentrations, which provide a kinetically feasible dehydration reaction channel of 1-propanol to propene. However, calculation results also indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration reaction. This work was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.

  14. The study of methanol transformation over Cu-modified ZSM-5, Beta zeolite and MCM-41 mesoporous silica using 11C-radioisotope labeling

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.

    2004-01-01

    Complete text of publication follows. The copper-containing zeolites and mesoporous silica, among other metals, are suitable for dehydrogenation of methanol. The Cu transition metal determines the route of methanol conversion on supports of ZSM-5 and Beta zeolite as well as MCM-41 mesoporous silica. The catalysis mechanism and the catalytic property are concluded from the composition of methanol derivates over Cu-modified catalysts. The Cu ion-exchanged ZSM-5 and Beta zeolite and MCM-41 mesoporous silica were synthesized and characterized using X-ray power diffraction, scanning electron microscope, nitrogen and pyridine adsorption, X-ray fluorescency and FTIR spectroscopy. The 11 C-radioactive labeling method ( 11 C radioisotope, T 1/2 = 20 min, is a gamma emitter by annihilation of its positron) is suitable for following the process of 11 C-methanol con- version i.e. adsorption, desorption and catalytic transformation as well as for investigation of small amounts of molecules over catalysts by very sensitive radioactivity detectors.The 11 C radioisotope was produced at cyclotron and the 11 C-methanol was synthesized by a classical radiochemical method. After catalysis the 11 C-radioactive and non radioactive volatile products were identified by radiogas chromatography hereby radiolabeled compound and -derivates were distinguished from other participant natural, nonradioactive carbon compounds. Along radioactive products dimethyl ether and small hydrocarbons products were formed by Bronsted acid sites of catalysts while formaldehyde and small methyl formate were formed by Cu metal over bifunctional Cu-ZSM-5, Cu-Beta zeolite and mesoporous Cu-MCM-41 silica at 240 deg C. The detection of methoxy methanol and dimethoxy methane confirmed the simultaneous presence of acid and basic sites of catalysts. At higher temperature (400 deg C) the CO and CO 2 final products were dominated. In our previous works, methanol conversion to hydrocarbons was observed by dehydration

  15. Facile synthesis of hierarchical nanocrystalline ZSM-5 zeolite under mild conditions and its catalytic performance.

    Science.gov (United States)

    Ni, Youming; Sun, Aiming; Wu, Xiaoling; Hai, Guoliang; Hu, Jianglin; Li, Tao; Li, Guangxing

    2011-09-15

    Hierarchical nanocrystalline ZSM-5 zeolite (NZ5) was synthesized at 100 °C under atmospheric pressure using methylamine as a mineralizing agent. The crystallization process of NZ5 was characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), and infrared spectroscopy (FTIR). The results of contrastive experiments showed that evaporation of the solvent promoted the aggregation of primary particles, and the addition of methylamine accelerated the crystallization process. The NZ5 aggregate consisted of 20 nm individual particles, as shown in scanning electron microscope (SEM). The lattice fringes in the transmission electron microscope (TEM) images and the XRD results indicated that individual particles of NZ5 were highly crystalline. N(2) adsorption-desorption isotherms showed that NZ5 had high BET surface areas with mesopores having a mean diameter of about 9 nm. NZ5 exhibited a long lifetime, a stable and high yield of liquid hydrocarbons, and a high anti-coking performance in methanol-to-hydrocarbons reaction. Catalytic testing and TGA results showed that the lifetime of NZ5 was about ten times longer than that of micro-sized ZSM-5 zeolite (MZ5), and the average coking rate with NZ5 was one fifth over that of MZ5. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao; Ren, Yanqun [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Gou, Jinsheng [College Material Science and Technology, Beijing Forestry University, Key Laboratory of Wooden Material Science and Application, Ministry of Education, 35 Tsinghua East Road, Haidian District, Beijing 100083 (China); Liu, Baoyu [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Xi, Hongxia, E-mail: cehxxi@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China)

    2017-01-15

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  17. Performance of modified H-ZSM-5 zeolite for dehydration of methanol to dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Hassanpour, Samaneh; Taghizadeh, Majid [Department of chemical engineering, Babol University of Technology, P.O. Box 484, 4714871167 Babol (Iran); Yaripour, Fereydoon [Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, Tehran (Iran)

    2010-10-15

    The conversion of methanol to dimethyl ether was carried out over various commercial zeolites and modified H-ZSM-5 catalysts to evaluate their catalytic performance. A series of commercially available zeolite samples were used for vapor-phase dehydration of methanol to DME. Catalyst screening tests were performed in a fixed-bed reactor under the same operating conditions (T = 300 S, P = 16 barg, WHSV = 3.8 h{sup -1}). It was found that all the H-form zeolite catalysts in this study were active and selective for DME synthesis. According to the experimental results MDHC-1 catalyst exhibited the highest activity in dehydration of methanol. After finding the most active catalyst, the H-MFI90 zeolite was modified with Na content varying from 0 to 120 mol%, via wet-impregnation method to further improve its selectivity. All of catalysts were characterized by BET, XRD, NH{sub 3}-TPD, ICP, TGA, SEM, FT-IR and TPH techniques. It was found that these materials affected activity of MDHC-1 zeolite by changing its acidity. Ultimately, among all the catalysts studied, Na{sub 100}-modified H-MFI90 zeolite exhibited optimum activity, selectivity and stability at methanol dehydration reaction. (author)

  18. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    International Nuclear Information System (INIS)

    Li, Chao; Ren, Yanqun; Gou, Jinsheng; Liu, Baoyu; Xi, Hongxia

    2017-01-01

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  19. Mesoporous ZSM-5 Zeolites in Acid Catalysis: Top-Down vs. Bottom-Up Approach

    Directory of Open Access Journals (Sweden)

    Pit Losch

    2017-07-01

    Full Text Available A top-down desilication of Al-rich ZSM-5 zeolites and a bottom-up mesopores creating method were evaluated in this study. Three liquid–solid and one gas–solid heterogeneously-catalysed reactions were chosen to establish relationships between zeolites textural properties and their catalytic behavior in acid-catalysed model reactions that are influenced by shape selectivity: Diels-Alder cyclization between isoprene and methylacrylate, Methanol-to-Olefins (MTO reaction, chlorination of iodobenzene with trichloroisocyanuric acid (TCCA, and Friedel-Crafts acylation of anisole by carboxylic acids with differing sizes. It is found amongst others that no optimal mesoporosity for all the different reactions can be easily obtained, but depending on the chosen application, a specific treatment has to be set to achieve high activity/selectivity and stability.

  20. Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

    KAUST Repository

    Zhu, Haibo; Abou-Hamad, Edy; Chen, Yin; Saih, Youssef; Liu, Weibing; Basset, Jean-Marie; Samal, Akshaya Kumar

    2016-01-01

    A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

  1. Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

    KAUST Repository

    Zhu, Haibo

    2016-02-08

    A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

  2. Hierarchical ZSM-5 zeolite:Synthesis and catalytic applications%多级孔道ZSM-5分子筛的合成及其催化应用

    Institute of Scientific and Technical Information of China (English)

    崔生航; 张君涛; 申志兵

    2015-01-01

    Due to high shape selectivity of microporous zeolite and the excellent mass transport of the mesoporous material,the hierarchical ZSM-5 zeolite has potential applications in catalytic field. The synthesis methods and application progress of hierarchical ZSM-5 zeolite in recent years are reviewed in this paper. Various approaches of hierarchical ZSM-5 zeolite synthesis were introduced,including post-treatment method,hard templating method and soft templating method. In addition,the catalytic applications of the as-synthesized zeolites were discussed. It was demonstrated that the reaction conversion and selectivity of target products were improved due to the excellent mass transport and appropriate acidity of the hierarchical ZSM-5 zeolite. This paper also forecasted the development of the hierarchical ZSM-5 zeolite in chemical industry. It was pointed out that the development of facile, economic and green routes towards the synthesis of hierarchical ZSM-5 zeolite would be a challenge in modern industrial catalysis. Research should focus on the mechanism of the mesopore formation,the development of the hierarchical ZSM-5 monolith zeolite as well as the supported hierarchical ZSM-5 zeolites.%多级孔道ZSM-5分子筛具有微孔沸石分子筛良好的择形催化性能和介孔材料优异的传质扩散性能,在催化领域显示出良好的应用前景.本文综述了近年来多级孔道 ZSM-5 分子筛的研究进展,重点介绍了多级孔道ZSM-5 分子筛的不同合成方法,包括后处理法、硬模板法和软模板法等,同时介绍了不同方法得到的多级孔道ZSM-5分子筛在催化反应中的应用,分析表明多级孔道ZSM-5分子筛以其良好的扩散性能和适宜的酸性提高了反应转化率和目标产物选择性.最后对多级孔道ZSM-5分子筛的发展方向进行了展望,指出研发简单、经济和环保的新合成路线是多级孔道ZSM-5分子筛发展中的重大挑战,深入研究多级孔道分子筛中介

  3. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    International Nuclear Information System (INIS)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo; Chang, Jong San; Qiu, Fa Li; Park, Sang Eon

    2004-01-01

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl 4 , was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl 4 with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl 4 was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis

  4. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Chang, Jong San; Qiu, Fa Li [Chinese Academy of Sciences(CAS), Chengdu (China); Park, Sang Eon [Inha University, Incheon (Korea, Republic of)

    2004-05-15

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl{sub 4}, was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl{sub 4} with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl{sub 4} was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis.

  5. Transformation of South African coal fly ash into ZSM-5 zeolite and its application as an MTO catalyst

    CSIR Research Space (South Africa)

    Missengue, RNM

    2017-01-01

    Full Text Available This study presents a way of using South African coal fly ash by extracting metals such as Al and Fe with concentrated sulphuric acid, and then using the solid residue as a feedstock for the synthesis of ZSM-5 zeolite. The percentage of aluminium...

  6. Shear-thickening behavior of Fe-ZSM5 zeolite slurry and its removal with alumina/boehmites

    Science.gov (United States)

    Liu, Xiao-guang; Li, Yan; Xue, Wen-dong; Sun, Jia-lin; Tang, Qian

    2018-06-01

    A cryogenic scanning electron microscopy (cryo-SEM) technique was used to explore the shear-thickening behavior of Fe-ZSM5 zeolite pastes and to discover its underlying mechanism. Bare Fe-ZSM5 zeolite samples were found to contain agglomerations, which may break the flow of the pastes and cause shear-thickening behaviors. However, the shear-thickening behaviors can be eliminated by the addition of halloysite and various boehmites because of improved particle packing. Furthermore, compared with pure Fe-ZSM5 zeolite samples and its composite samples with halloysite, the samples with boehmite (Pural SB or Disperal) additions exhibited network structures in their cryo-SEM images; these structures could facilitate the storage and release of flow water, smooth paste flow, and avoid shear-thickening. By contrast, another boehmite (Versal 250) formed agglomerations rather than network structures after being added to the Fe-ZSM5 zeolite paste and resulted in shear-thickening behavior. Consequently, the results suggest that these network structures play key roles in eliminating the shear-thickening behavior.

  7. Hexane cracking over steamed phosphated zeolite H-ZSM-5 : Promotional effect on catalyst performance and stability

    NARCIS (Netherlands)

    Van Der Bij, Hendrik E.; Meirer, Florian; Kalirai, Samanbir; Wang, Jian; Weckhuysen, Bert M.

    2014-01-01

    The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of 27Al and 31P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3

  8. Multinuclear MAS NMR studies on coked zeolites H-ZSM-5

    International Nuclear Information System (INIS)

    Ernst, H.; Freude, D.; Hunger, M.; Pfeifer, H.

    1991-01-01

    During the cracking process carbonaceous materials are deposited on the outer or inner surface of the catalyst. These deposits are in many cases the main cause of catalyst deactivation. Magic angle spinning (MAS) NMR investigations and catalytic n-hexane cracking were carried out on H-ZSM-5 zeolites after a mild hydrothermal de-alumination. By 13 C CP MAS NMR it could be shown that the enhanced catalytic activity does not enhance the coke formation and that the chemical nature of these deposits is essentially aromatic. From 1 H MAS NMR studies performed on shallow-bed activated sealed samples and 27 Al and 29 Si MAS NMR on rehydrated samples it follows that for high coke concentrations the catalyst deactivation is caused mainly by blocking of Broensted acid sites. (author). 27 refs.; 3 figs.; 2 tabs

  9. Transalkylation of ethyl benzene with triethylbenzene over ZSM-5 zeolite catalyst

    KAUST Repository

    Akhtar, M. Naseem

    2010-09-01

    Transalkylation of 1,3,5-triethylbenzene (TEB) with ethylbenzene (EB) has been studied over ZSM-5 zeolite using a riser simulator reactor with respect to optimizing DEB yield. The reaction temperature was varied from 350 to 500°C with contact time ranging from 3 to 15s to report on the effect of reaction conditions on TEB conversion, DEB selectivity and isomerization of TEB. The transalkylation of TEB with EB was compared with the reactions of pure 1,3,5-TEB and EB (disproportionation, isomerization and cracking). A synergistic effect was observed on the conversion of 1,3,5-TEB and DEB yield. The 1,3,5-TEB conversion increased from 40% to 50% with simultaneous increase in the DEB selectivity from 17% to 36% in transalkylation reaction (EB+1,3,5-TEB) as compared with the reaction of pure 1,3,5-TEB. It was found that pure 1,3,5-TEB underwent cracking reaction to produce DEB and EB. The isomerization of 1,3,5-TEB was more active at low temperature while cracking was more active at high temperature. The temperature of 350°C was observed as the optimum for production of maximum amount of DEB. Kinetic parameters for the disappearance of 1,3,5-TEB during its transformation reaction via cracking and isomerization pathways were calculated using the catalyst activity decay function based on time-on-stream (TOS). The apparent activation energies decrease in order E secondary cracking>E primary racking>E isomerization for ZSM-5 catalysts. © 2010 Elsevier B.V.

  10. Highly Oriented Growth of Catalytically Active Zeolite ZSM-5 Films with a Broad Range of Si/Al Ratios.

    Science.gov (United States)

    Fu, Donglong; Schmidt, Joel E; Ristanović, Zoran; Chowdhury, Abhishek Dutta; Meirer, Florian; Weckhuysen, Bert M

    2017-09-04

    Highly b-oriented zeolite ZSM-5 films are critical for applications in catalysis and separations and may serve as models to study diffusion and catalytic properties in single zeolite channels. However, the introduction of catalytically active Al 3+ usually disrupts the orientation of zeolite films. Herein, using structure-directing agents with hydroxy groups, we demonstrate a new method to prepare highly b-oriented zeolite ZSM-5 films with a broad range of Si/Al ratios (Si/Al=45 to ∞). Fluorescence micro-(spectro)scopy was used to monitor misoriented microstructures, which are invisible to X-ray diffraction, and show Al 3+ framework incorporation and illustrate the differences between misoriented and b-oriented films. The methanol-to-hydrocarbons process was studied by operando UV/Vis diffuse reflectance micro-spectroscopy with on-line mass spectrometry, showing that the b-oriented zeolite ZSM-5 films are active and stable under realistic process conditions. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  11. Hydrogen/Denterium exchange during n.butane conversion on H-ZSM-5

    NARCIS (Netherlands)

    Narbeshuber, T.; Narbeshuber, Thomas F.; Stockenhuber, Michael; Brait, Axel; Brait, A.; Seshan, Kulathuiyer; Lercher, J.A.

    1996-01-01

    Steady-state isotope tracer studies and isotope transient response experiments ofn-butane conversion on H-ZSM-5 (Si/Al = 35) were carried out between 673 and 823 K. Among the three main reactions, the rate of H/D-exchange is at least one order of magnitude higher compared to the rates of cracking or

  12. Mechanistic studies on the transformation of ethanol into ethene over Fe-ZSM-5 zeolite.

    Science.gov (United States)

    Maihom, Thana; Khongpracha, Pipat; Sirijaraensre, Jakkapan; Limtrakul, Jumras

    2013-01-14

    Ethanol, through the utilization of bioethanol as a chemical resource, has received considerable industrial attention as it provides an alternative route to produce more valuable hydrocarbons. Using a density functional theory approach incorporating the M06-L functional, which includes dispersion interactions, a large 34T nanocluster model of Fe-ZSM-5 zeolite in which T is a Si or Al atom is employed to examine both the stepwise and concerted mechanisms of the transformation of ethanol into ethene. For the stepwise mechanism, ethanol dehydration commences from the first hydrogen abstraction of the ethanol OH group to form the ethoxide-hydroxide intermediate with a low activation energy of 17.7 kcal mol(-1). Consequently, the ethoxide-hydroxide intermediate is decomposed into ethene through hydrogen abstraction from the ethoxide methyl carbon to either the OH group of hydroxide or the oxygen of the ethoxide group with high activation energies of 64.8 and 63.5 kcal mol(-1), respectively. For the concerted mechanism, ethanol transformation into the ethene product occurs in a single step without intermediate formation, with an activation energy of 32.9 kcal mol(-1). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Hydronium-Ion-Catalyzed Elimination Pathways of Substituted Cyclohexanols in Zeolite H-ZSM5

    Energy Technology Data Exchange (ETDEWEB)

    Hintermeier, Peter H. [Department; Eckstein, Sebastian [Department; Mei, Donghai [Institute; Olarte, Mariefel V. [Institute; Camaioni, Donald M. [Institute; Baráth, Eszter [Department; Lercher, Johannes A. [Department; Institute

    2017-10-02

    Hydronium ions in the pores of zeolite H-ZSM5 show high catalytic activity in the elimination of water from cyclohexanol in aqueous phase. Substitution induces subtle changes in rates and reaction pathways, which are concluded to be related to steric effects. Exploring the reaction pathways of 2-, 3-, and 4-methylcyclohexanol (2-McyOH, 3-McyOH, and 4-McyOH), 2- and 4-ethylcyclohexanol (2-EcyOH and 4-EcyOH), 2-n-propylcyclohexanol (2-PcyOH), and cyclohexanol (CyOH) it is shown that the E2 character increases with closer positioning of the alkyl and hydroxyl groups. Thus, 4-McyOH dehydration proceeds via an E1-type elimination, while cis-2-McyOH preferentially reacts via an E2 pathway. The entropy of activation decreased with increasing alkyl chain length (ca. 20 J mol-1 K-1 per CH2 unit) for 2-substituted alcohols, which is concluded to result from constraints influencing the configurational entropy of the transition states.

  14. Pyrolysis of soybean oil with H-ZSM5 (Proton-exchange of Zeolite Socony Mobil 5) and MCM41 (Mobil Composition of Matter No. 41) catalysts in a fixed-bed reactor

    International Nuclear Information System (INIS)

    Ngo, Thanh-An; Kim, Jinsoo; Kim, Sun Kuk; Kim, Seung-Soo

    2010-01-01

    Soybean oil was pyrolyzed with various catalysts in a fixed-bed reactor under nitrogen flow at 420 and 450 o C. The H-ZSM5 catalysts (molar ratio SiO 2 /Al 2 O 3 = 28, 40, and 180) and 2 wt% (Ga, Al or Cu) impregnated MCM41 catalysts were used in order to investigate the effect of catalysts during the pyrolysis process. The gas products in all experiments were mainly methane, ethane and propylene. The liquid products in the presence of H-ZSM5 catalysts were mainly aromatic components while those with metal/MCM41 catalysts were a mixture of alkanes, alkenes, alkadienes, aromatic and carboxylic acids. The highest coke yield of 4.4 wt% was obtained with Ga/MCM41 catalyst at the pyrolysis temperature of 420 o C. The effect of catalysts on product yield and composition was systematically investigated.

  15. High Yield of Liquid Range Olefins Obtained by Converting i-Propanol over Zeolite H-ZSM-5

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Shunmugavel, Saravanamurugan; Hruby, S.L.

    2009-01-01

    Methanol, ethanol, and i-propanol were converted under methanol-to-gasoline (MTH)-like conditions (400 degrees C, 1-20 bar) over zeolite H-ZSM-5. For methanol and ethanol, the catalyst lifetimes and conversion capacities are comparable, but when i-propanol is used as the reactant, the catalyst...... lifetime is increased dramatically. In fact, the total conversion capacity (calculated as the total amount of alcohol converted before deactivation in g(alcohol)/g(zeolite)) is more than 25 times higher for i-propanol compared to the lower alcohols. Furthermore, when i-propanol is used as the reactant...

  16. Conversion of straight-run gas-condensate benzenes into high- octane gasolines based on modified ZSM-5 zeolites

    International Nuclear Information System (INIS)

    Erofeev, V; Reschetilowski, V; Khomajakov, I; Egorova, L; Volgina, T; Tatarkina, A

    2014-01-01

    This paper describes the conversion of straight-run benzene of gas condensate into high-octane gasoline based on zeolite catalyst ZSM-5, modified in binary system oxide- based Sn (III) and Bi (III). It was defined that the introduction of the binary system oxide-based Sn(III) and Bi (III) into the basic zeolite results in the 2-fold increase of its catalytic activity.High-octane gasoline converted from straight-run benzene is characterized by a low benzol content in comparison to the high-octane benzenes produced during the catalytic reforming

  17. Small-angle neutron scattering studies of the template-mediated crystallization of ZSM-5 type zeolite

    International Nuclear Information System (INIS)

    Iton, L.E.; Brun, T.O.; Epperson, J.E.

    1988-03-01

    Small-angle neutron scattering is a useful new approach to the study of zeolite crystallization from aluminosilicate gels and the action of template molecules. It has been applied to gels for synthesis of zeolite ZSM-5 using tetrapropylammonium ions as templates where the scattering length densities of the gel particles and their texture were determined using contrast variation methods. Gels formulated from soluble silicate incorporate template molecules promptly into an amorphous ''embryonic'' structure and crystallization ensues via a solid hydrogel transformation mechanism. Gels formulated from colloidal silica show different scattering behavior, and a liquid phase transport mechanism is inferred. 8 refs., 4 figs., 2 tabs

  18. Elastic behavior of MFI-type zeolites: Compressibility of H-ZSM-5 in penetrating and non-penetrating media

    International Nuclear Information System (INIS)

    Quartieri, Simona; Montagna, Gabriele; Arletti, Rossella; Vezzalini, Giovanna

    2011-01-01

    The elastic behavior of H-ZSM-5 was investigated by in-situ synchrotron X-ray powder diffraction, using both silicone oil (s.o.) and (16:3:1) methanol:ethanol:water (m.e.w.) as 'non-penetrating' and 'penetrating' pressure transmitting media, respectively. From P amb to 6.2 GPa the volume reduction observed in s.o. is 16.6%. This testifies that H-ZSM-5 is one of the most flexible microporous materials up to now compressed in s.o. Volume reduction observed in m.e.w. up to 7.6 GPa is 14.6%. A strong increase in the total electron number of the extraframework system, due to the penetration of water/alcohol molecules in the pores, is observed in m.e.w. This effect is the largest up to now observed in zeolites undergoing this phenomenon without cell volume expansion. The higher compressibility in s.o. than in m.e.w. can be ascribed to the penetration of the extra-water/alcohol molecules, which stiffen the structure and contrast the channel deformations. - Graphical abstract: High-pressure behavior of H-ZSM-5 compressed in (16:3:1) methanol:ethanol:water: (a) projection of the structure along the [0 1 0] direction at P amb , 2 GPa and after pressure release to original ambient conditions (P amb (rev)), and (b) P-dependence of the extraframework content expressed as total number of electrons (gray square represents the number of the extraframework electrons at P amb after decompression). Highlights: → X-ray powder diffraction study of H-ZSM-5 compressibility. → H-ZSM-5 is one of the softest porous material compressed in silicon oil. → Penetration of additional water/alcohol molecules upon compression in m.e.w. → Extra molecules contribute to stiffen the structure and to contrast HP effects.

  19. Enhanced catalytic performance for light-olefins production from chloromethane over hierarchical porous ZSM-5 zeolite synthesized by a growth-inhibition strategy

    Science.gov (United States)

    Liu, Qing; Wen, Dafen; Yang, Yanran; Fei, Zhaoyang; Zhang, Zhuxiu; Chen, Xian; Tang, Jihai; Cui, Mifen; Qiao, Xu

    2018-03-01

    Hierarchical porous ZSM-5 (HP-ZSM-5) zeolites were synthesized by hydrothermal crystallization method adding triethoxyvinylsilane as the growth-inhibitor at different hydrothermal crystallized temperatures. The properties of the obtained samples were characterized by XRD, SEM, N2-sorption, uptake of ethylene, 27Al MAS NMR, NH3-TPD, and Py-IR. It was found that the mesopore was introduced and the acidity was adjusted over HP-ZSM-5 samples successfully. The hydrothermal crystallized temperature had an important influence on the porous structure and surface properties. The catalytic performance for chloromethane to light-olefins (CMTO) were also investigated. Compared with ZSM-5 samples, HP-ZSM-5 samples exhibited enhanced stability and increased selectivity of light-olefins for CMTO reaction because of the introduction of the abundant mesopore and appropriate acidity. The lifetime (the duration of chloromethane conversion >98%) and selectivity of light-olefins reached 115 h and 69.3%, respectively.

  20. Preparation of 13X from Waste Quartz and Photocatalytic Reaction of Methyl Orange on TiO2/ZSM-5, 13X and Y-Zeolite.

    Science.gov (United States)

    Wang, Jia-Jie; Jing, You-Hai; Ouyang, Tong; Chang, Chang-Tang

    2015-08-01

    TiO2 photocatalytic reactions not only remove a variety of organic pollutants via complete mineralization, but also destroy the bacterial cell wall and cell membrane, thus playing an important bactericidal role. However, the post-filtration procedures to separate nanometer-levels of TiO2 and the gradual inactivity of photocatalyst during continuous use are defects that limit its application. In this case, we propose loading TiO2 on zeolite for easy separation and 13X is considered as a promising one. In our study, 13X-zeolite was prepared by a hydrothermal method and the source of Si was extracted from waste quartz sand. For comparison, commercial zeolite with different microporous and mesoporous diameters (ZSM-5 and Y-zeolites) were also used as TiO2 supports. The pore size of the three kinds of zeolites are as follows: Y-zeolite > 13X > ZSM-5. Different TiO2 loading content over ZSM-5, 13X and Y-zeolite were prepared by the sol-gel method. XRD, FTIR, BET, UV-vis, TGA and SEM were used for investigation of material characteristics. In addition, the efficiencies of mineralization and photodegradation were studied in this paper. The effects of the loading ratio of TiO2 over zeolites, initial pH, and concentration on photocatalytic performance are investigated. The relationship between best loading content of TiO2 and pore size of the zeolite was studied. The possible roles of the ZSM-5, 13X-zeolites and Y-zeolites support on the reactions and the possible mechanisms of effects were also explored. The best loading content of TiO2 over ZSM-5, 13X and Y-zeolite was found to be 50 wt%, 12.5 wt% and 7 wt%, respectively. The optimum pH condition is 3 with TiO2 over ZSM-5, 13X-zeolites and Y-zeolites. The results showed that the degradation and mineralization efficiency of 12.5 wt%GT13X (TiO2 over 13X) after 90 min irradiation reached 57.9% and 22.0%, which was better than that of 7 wt%GTYZ (TiO2 over Y-zeolites) while much lower than that of 50 wt%GTZ (TiO2 over ZSM-5

  1. Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

    Science.gov (United States)

    Krisnandi, Y. K.; Yanti, F. M.; Murti, S. D. S.

    2017-04-01

    Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO4 4-) and aluminate (AlO4 5-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (v asymetric T-O), 820-650 cm-1 (v symetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

  2. Production of furfural from waste aqueous hemicellulose solution of hardwood over ZSM-5 zeolite.

    Science.gov (United States)

    Gao, Hongling; Liu, Haitang; Pang, Bo; Yu, Guang; Du, Jian; Zhang, Yuedong; Wang, Haisong; Mu, Xindong

    2014-11-01

    This study aimed to produce furfural from waste aqueous hemicellulose solution of a hardwood kraft-based dissolving pulp production processing in a green method. The maximum furfural yield of 82.4% and the xylose conversion of 96.8% were achieved at 463K, 1.0g ZSM-5, 1.05g NaCl and organic solvent-to-aqueous phase ratio of 30:15 (V/V) for 3h. The furfural yield was just 51.5% when the same concentration of pure xylose solution was used. Under the optimized condition, furfural yield was still up to 67.1% even after the fifth reused of catalyst. Catalyst recycling study showed that ZSM-5 has a certain stability and can be efficiently reused. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Thermochemical properties of copper forms of zeolite ZSM5 containing dimethylethylenediamine

    Czech Academy of Sciences Publication Activity Database

    Čuvanová, S.; Reháková, M.; Finocchiaro, P.; Pollicino, A.; Bastl, Zdeněk; Nagyová, S.; Fajnor, V. Š.

    2007-01-01

    Roč. 452, č. 1 (2007), s. 13-19 ISSN 0040-6031 R&D Projects: GA AV ČR 1ET400400413 Grant - others:GA SR(SK) 1/1385/04; GA SR(SK) 1/1373/04 Institutional research plan: CEZ:AV0Z40400503 Keywords : ZSM-5 * dimethylethylenediamine * copper * thermal analysis * XPS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.562, year: 2007

  4. Determining the efficiency of ZSM-5 zeolite impregnated with nanoparticles of titanium dioxide in the photocatalytic removal of styrene vapors

    Directory of Open Access Journals (Sweden)

    Mojtaba Nakhaei pour

    2017-03-01

    Full Text Available Introduction: Styrene monomer is a volatile organic compound that has many applications particularly in plastic, rubber and paint industries. According to the harmful effects of these compounds on human and environment, reducing and controling of them seem necessary. Therefore, in this study removal of styrene was investigated using photocatalytic process of titanium dioxide nanoparticles stabilized on ZSM-5. Methods: After stabilization of titanium dioxide nanoparticles on ZSM-5 zeolite, BET, SEM and XRD analysis were used to determine the characteristics of nanoparticles. Experiments were conducted at ambient temperature in laboratory scale. Concentration of produced styrene in the experiments was 50 and 300 ppm, and input flow rate was 1 l/min. Results: images and spectra obtained through XRD and SEM-EDAX showed that  nano-catalysts are well- stabilized. The results showed that by increasing of input concentration of styrene from 50 to 300 ppm, photocatalytic removal efficiency are reduced. Also, adsorption capacity of the catalyst bed in concentrations of 50 and 300 ppm was calculated 16.3 and19.4 mg/gr of adsorbent respectively. Conclusion: The results show that the use of hybrid bed can increase the removal efficiency of contaminants. And due to low cost of application of these systems compared to conventional methods, it is recommended that more comprehensive studies to be done regarding the optimization of the parameters affecting the process of photocatalytic removal.

  5. New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study

    NARCIS (Netherlands)

    Karwacki, L.|info:eu-repo/dai/nl/304824283; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2011-01-01

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy was used to study the template decomposition process in large zeolite ZSM-5 crystals. Correlation of polarized light dependent UV-Vis absorption spectra with confocal fluorescence emission spectra in the 400–750 nm region

  6. Heterobimetallic Zeolite, InV-ZSM-5, Enables Efficient Conversion of Biomass Derived Ethanol to Renewable Hydrocarbons.

    Science.gov (United States)

    Narula, Chaitanya K; Li, Zhenglong; Casbeer, Erik M; Geiger, Robert A; Moses-Debusk, Melanie; Keller, Martin; Buchanan, Michelle V; Davison, Brian H

    2015-11-03

    Direct catalytic conversion of ethanol to hydrocarbon blend-stock can increase biofuels use in current vehicles beyond the ethanol blend-wall of 10-15%. Literature reports describe quantitative conversion of ethanol over zeolite catalysts but high C2 hydrocarbon formation renders this approach unsuitable for commercialization. Furthermore, the prior mechanistic studies suggested that ethanol conversion involves endothermic dehydration step. Here, we report the complete conversion of ethanol to hydrocarbons over InV-ZSM-5 without added hydrogen and which produces lower C2 (dehydration step is not necessary. Thus, our method of direct conversion of ethanol offers a pathway to produce suitable hydrocarbon blend-stock that may be blended at a refinery to produce fuels such as gasoline, diesel, JP-8, and jet fuel, or produce commodity chemicals such as BTX.

  7. Coke burning behavior of a catalyst of ZSM-5/ZSM-11 co-crystallized zeolite in the alkylation of benzene with FCC off-gas to ethylbenzene

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yi; Zhai, Yuchun [Northeastern University, Shenyang, 110006 (P. R. China); Liu, Shenglin; Wang, Qingxia; Xu, Longya [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, P. O. Box 110, Dalian 116023 (P. R. China)

    2006-04-15

    Since the commercialization of ethylbenzene production via alkylation of benzene with the dilute ethene in FCC off-gas over a ZSM-5/ZSM-11 co-crystallized zeolite catalyst in China, the catalyst has been regenerated several times and showed good regeneration performance. During the alkylation process, the catalytic activity decreases, some of the catalyst pores are blocked and the acid centers are partly covered by coke deposition. Influence of the factors such as catalyst particle size, temperature, etc. on the burning rate of the coke was investigated by the TG technique, and a rate equation for coke burning on the ZSM-5/ZSM-11 co-crystallized catalyst was established. (author)

  8. Radioactive (14C) tracer studies of methanol conversion over a Ni-ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Hwu, F.S.; Hightower, J.W.

    1983-01-01

    Secondary reactions have been identified in the overall conversion of methanol to hydrocarbons over a Ni-ZSM-5 catalyst. The major conclusions are: (1) The alkylation of light olefins with methanol or methyl ether is one pathway for the formation of larger olefins with one more carbon atom. (2) Paraffins are produced primarily by hydrogen transfer to the corresponding olefin. (3) Except for minor cracking reactions, paraffins with no more than 7 carbon atoms, are final stable products; isomerization among paraffin isomers does not take place at 368 0 C. (4) Light olefins, e.g. ethylene, propylene, and butenes, are reactive intermediates for aromatics formation. (5) Aromatic compounds may also be produced by methanol- methyl ether-alkylation of benzene and subsequent alkylated benezenes. 2 figures, 3 tables

  9. Encapsulation of ferro- and ferricyanide complexes inside ZSM-5 zeolite synthesized from rice straw: Implications for synthesis of Prussian blue pigment

    International Nuclear Information System (INIS)

    Ali, Ibraheem O.; Salama, Tarek M.; Thabet, Mohamed S.; El-Nasser, Karam S.; Hassan, Ali M.

    2013-01-01

    Encapsulation of [Fe(CN) 6 ] 4− and [Fe(CN) 6 ] 3− complexes in the intracrystalline pores of ZSM-5 zeolite, Fe II L/Z and Fe III L/Z respectively, by the zeolite synthesis method was reported. The modified zeolites were characterized by powder XRD, FT-IR and UV–vis spectroscopy. The nitrogen adsorption isotherms allow for the evaluation of pore structure of the complex-modified zeolites, whereas the thermal analysis (TGA/DTA) measurements provide insight into the decomposition products of the immobilized complexes. The modified zeolites exhibited smaller pore volumes and surface areas as compared with those of unpromoted ZSM-5, suggesting the inclusion of iron cyanides inside the interconnecting channels of ZSM-5. While the ferricyanide complex enhanced the formation of highly crystalline zeolite, the ferrocyanide one resulted in a lesser effect. The electronic spectra of the colloidal species developed when Fe III L/Z brought in contact with an aqueous solution of [Fe(CN) 6 ] 3− exhibit absorptions attributed to CN − → iron charge-transfer. New bands at 294 and 319 nm due to d–d transitions of Fe III tetrahedral monomeric moieties were emitted concurrently under successive adsorption of [Fe(CN) 6 ] aq 3− over Fe III L/Z, along with a broad band at 555 nm assigned to polymeric [Fe II –C–N–Fe III ] of Prussian blue (PB). The FT-IR spectra of Fe III/II L/Z devoted to the adsorption of an aqueous solution of [Fe(CN) 6 ] 3− showed a band at 2092 cm −1 assigned to the C–N stretch in the Fe II –CN–Fe III linkages. The vibrations attributable to Fe–O–Si bonding along with hydrocarbon and nitroprusside appeared only in the spectrum of Fe III L/Z, thus was found to be strong evidence for the mutual interaction between [Fe(CN) 6 ] 3− and the latter sample. - Highlights: • We synthesized ferrous and ferric cyanide complexes inside ZSM-5 zeolite. • The decomposition of the encapsulated complexes occurred at high temperatures.

  10. Encapsulation of ferro- and ferricyanide complexes inside ZSM-5 zeolite synthesized from rice straw: Implications for synthesis of Prussian blue pigment

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ibraheem O.; Salama, Tarek M., E-mail: tm_salama@yahoo.com; Thabet, Mohamed S.; El-Nasser, Karam S.; Hassan, Ali M.

    2013-06-15

    Encapsulation of [Fe(CN){sub 6}]{sup 4−} and [Fe(CN){sub 6}]{sup 3−} complexes in the intracrystalline pores of ZSM-5 zeolite, Fe{sup II}L/Z and Fe{sup III}L/Z respectively, by the zeolite synthesis method was reported. The modified zeolites were characterized by powder XRD, FT-IR and UV–vis spectroscopy. The nitrogen adsorption isotherms allow for the evaluation of pore structure of the complex-modified zeolites, whereas the thermal analysis (TGA/DTA) measurements provide insight into the decomposition products of the immobilized complexes. The modified zeolites exhibited smaller pore volumes and surface areas as compared with those of unpromoted ZSM-5, suggesting the inclusion of iron cyanides inside the interconnecting channels of ZSM-5. While the ferricyanide complex enhanced the formation of highly crystalline zeolite, the ferrocyanide one resulted in a lesser effect. The electronic spectra of the colloidal species developed when Fe{sup III}L/Z brought in contact with an aqueous solution of [Fe(CN){sub 6}]{sup 3−} exhibit absorptions attributed to CN{sup −} → iron charge-transfer. New bands at 294 and 319 nm due to d–d transitions of Fe{sup III} tetrahedral monomeric moieties were emitted concurrently under successive adsorption of [Fe(CN){sub 6}]{sub aq}{sup 3−} over Fe{sup III}L/Z, along with a broad band at 555 nm assigned to polymeric [Fe{sup II}–C–N–Fe{sup III}] of Prussian blue (PB). The FT-IR spectra of Fe{sup III/II}L/Z devoted to the adsorption of an aqueous solution of [Fe(CN){sub 6}]{sup 3−} showed a band at 2092 cm{sup −1} assigned to the C–N stretch in the Fe{sup II}–CN–Fe{sup III} linkages. The vibrations attributable to Fe–O–Si bonding along with hydrocarbon and nitroprusside appeared only in the spectrum of Fe{sup III}L/Z, thus was found to be strong evidence for the mutual interaction between [Fe(CN){sub 6}]{sup 3−} and the latter sample. - Highlights: • We synthesized ferrous and ferric cyanide

  11. Mesoporous Fe-containing ZSM-5 zeolite single crystal catalysts for selective catalytic reduction of nitric oxide by ammonia

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Egeblad, Kresten; Kustova, Marina

    2007-01-01

    Mesoporous and conventional Fe-containing ZSM-5 catalysts (0.5–8 wt% Fe) were prepared using a simple impregnationmethod and tested in NO selective catalytic reduction (SCR) with NH3. It was found that mesoporous Fe-ZSM-5 catalysts exhibit higher SCR activities than comparable conventional cataly...

  12. Hierarchical ZSM-5 zeolite catalysts for the selective oxidation of benzene

    NARCIS (Netherlands)

    Koekkoek, A.J.J.

    2011-01-01

    Zeolites are widely used as catalysts, especially in oil refining and the petrochemical industries. Nowadays the cracking of heavy oil feeds as well as the processing of larger (bio)molecules demands for improved catalysts that can overcome the pore size constraints and diffusion limitations of the

  13. Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5.

    Science.gov (United States)

    Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

    2016-08-25

    We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

  14. The direct hydroxylation of benzene to phenol catalyzed by Fe-ZSM-5 zeolite : a DFT and hybrid MP2:DFT calculation

    NARCIS (Netherlands)

    Yang, Z.; Yang, G.; Liu, X.; Han, Xiuwen

    2013-01-01

    The title reactions over Fe-III and Fe-II-ZSM-5 zeolites are divided into seven and six steps, wherein the M06L:B3LYP energy barriers of N2O decomposition to form active site, benzene activation to form C-O bond and proton transfer to form phenol are equal to 37.0, 13.7, 17.2 and 33.7, 3.0, 19.1

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

    Science.gov (United States)

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

    2018-05-01

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

  16. Alkaline leaching for synthesis of improved Fe-ZSM5 catalysts

    NARCIS (Netherlands)

    Espinosa, S; Mentruit, C; Kapteijn, F; Moulijn, JA; Melián-Cabrera, I.

    Fe-ZSM5 catalysts were fully Fe-exchanged by pretreating the parent zeolite with base a solution prior to the Fe-exchange. The catalysts prepared in this way showed very low amount of inactive FeOx and improved performance in N2O decomposition. Alkaline leaching breaks down the zeolite crystals -

  17. Fabrication of novel chitosan/PAN/magnetic ZSM-5 zeolite coated sponges for absorption of oil from water surfaces.

    Science.gov (United States)

    Samadi, Saman; Yazd, Shabnam Sharif; Abdoli, Hossein; Jafari, Pooya; Aliabadi, Majid

    2017-12-01

    In the present study, the chitosan (bottom layer)/polyacrylonitrile (top layer, PAN) nanofibers were coated on the sponge surface. The synthesized magnetic Fe 3 O 4 - ZSM-5 nanozeolites have been loaded into the chitosan/PAN nanofibers to increase the performance of nanofibers toward absorption of lubricating oil, motor oil and pump oil from water surfaces. Scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis were used to characterize the synthesized nanozeolites. The morphology and wettability of nanofibers were determined using SEM and water contact angle tests. The influence of Fe 3 O 4 - ZSM-5 nanozeolite content and chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofiber thickness was evaluated on the potential of sponges for oils absorption. The maximum capacity of the chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofibers coated sponges for absorption of motor oil, lubricating oil and pump oil was found to be 99.4, 95.3 and 88.1g/g, in Fe 3 O 4 - ZSM-5 2wt.% and nanofiber thickness of 12μm (chitosan layer of 2μm and PAN layer of 10μm). The reusability of nanofibrous sponges showed that the hydrophobic chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofibers coated sponges can be easily reused in water-oil separation for many cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Synthesis of ZSM-5 and Co-ZSM-5 starting from inorganic systems

    International Nuclear Information System (INIS)

    Zapata N, Mauren; Montes Consuelo; Villa Aida Luz

    1995-01-01

    ZSM-5 was obtained in a completely inorganic system. Besides, several experiments were carried out to introduce Co+2 in the Framework of inorganic ZSM-5. The addition of a cobalt source to the precursor gel increased the time to obtain ZSM-5 crystals compared to the gel without a cobalt source. Furthermore, thermal stability over 500 was lower in Co-ZSM-5. Chemical analysis suggests that some cobalt was in the channels, since it was removed by ion exchange

  19. Deactivation of Zeolite Catalyst H-ZSM-5 during Conversion of Methanol to Gasoline: Operando Time- and Space-Resolved X-ray Diffraction.

    Science.gov (United States)

    Rojo-Gama, Daniel; Mentel, Lukasz; Kalantzopoulos, Georgios N; Pappas, Dimitrios K; Dovgaliuk, Iurii; Olsbye, Unni; Lillerud, Karl Petter; Beato, Pablo; Lundegaard, Lars F; Wragg, David S; Svelle, Stian

    2018-03-15

    The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion of methanol to hydrocarbons was monitored by high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution was achieved by continuous scanning along the axial length of a capillary fixed bed reactor with a time resolution of 10 s per scan. Using real structural parameters obtained from XRD, we can track the development of coke at different points in the reactor and link this to a kinetic model to correlate catalyst deactivation with structural changes occurring in the material. The "burning cigar" model of catalyst bed deactivation is directly observed in real time.

  20. Proton proximity – New key parameter controlling adsorption, desorption and activity in propene oligomerization over H-ZSM-5 zeolites

    Czech Academy of Sciences Publication Activity Database

    Bernauer, Milan; Tabor, Edyta; Pashková, Veronika; Kaucký, Dalibor; Sobalík, Zdeněk; Wichterlová, Blanka; Dědeček, Jiří

    2016-01-01

    Roč. 344, DEC 2016 (2016), s. 157-172 ISSN 0021-9517 R&D Projects: GA ČR GA15-13876S; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388955 Keywords : ZSM-5 * Al siting * Single Al Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.844, year: 2016

  1. Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH_3

    International Nuclear Information System (INIS)

    Zhang, Tao; Shi, Juan; Liu, Jian; Wang, Daxi; Zhao, Zhen; Cheng, Kai; Li, Jianmei

    2016-01-01

    Highlights: • The hydrothermal stability of Cu-ZSM-5 catalyst was enhanced after surface modification. • An inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer. • The contact between Si and Cu and Al atoms could form Si-O-Al and Si- O−Cu bonds. • The redox and acidity properties of Cu-ZSM-5-CLD-Aged catalyst were largely retained. • The adsorption and activation of NO and NH_3 was almost unchanged over Cu-ZSM-5-CLD catalyst before and after hydrothermal treatment. - Abstract: The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH_3. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu"2"+ from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

  2. Effects of Coke Deposits on the Catalytic Performance of Large Zeolite H-ZSM-5 Crystals during Alcohol-to-Hydrocarbon Reactions as Investigated by a Combination of Optical Spectroscopy and Microscopy

    NARCIS (Netherlands)

    Nordvang, Emily C.; Borodina, Elena; Ruiz-Martinez, Javier; Fehrmann, Rasmus; Weckhuysen, Bert M.

    2015-01-01

    The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ

  3. Linkage isomerism of carbonyl coordination complexes formed upon CO adsorption on the zeolite Li-ZSM-5: variable-temperature FTIR studies

    Science.gov (United States)

    Otero Areán, C.; Rodríguez Delgado, M.; Manoilova, O. V.; Turnes Palomino, G.; Tsyganenko, A. A.; Garrone, E.

    2002-08-01

    Carbon monoxide adsorbed at a low-temperature on the zeolite Li-ZSM-5 forms Li +⋯CO and Li +⋯(CO) 2 species characterized by C-O stretching bands at 2195 and 2187 cm-1, respectively. These C-bonded carbonyls are in a temperature-dependent equilibrium with Li +⋯OC and CO⋯Li +⋯CO species having O-bonded CO. By means of variable-temperature FTIR spectroscopy, the enthalpy change involved in the corresponding isomerization process was found to be ΔH°=7.8 kJ mol-1 for the monocarbonyl and ΔH°=5.1 kJ mol-1 for the dicarbonyl. Therefore, although C-bonded species were always found to show a higher cation-CO interaction energy than O-bonded species, the difference is smaller in the case of dicarbonyls.

  4. Effects of Coke Deposits on the Catalytic Performance of Large Zeolite H-ZSM-5 Crystals during Alcohol-to-Hydrocarbons Reactions as Investigated by a Combination of Optical Spectroscopy and Microscopy

    DEFF Research Database (Denmark)

    Nordvang, Emily Catherine; Borodina, Elena; Ruiz-Martínez, Javier

    2015-01-01

    The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ...... single crystal UV/Vis and confocal fluorescence micro-spectroscopy, allowing the observation of the spatiotemporal formation of intermediates and coke species during the MTO and ETO conversions. It was observed that rapid deactivation at elevated temperatures was due to the fast formation of aromatics...... at the periphery of the H-ZSM-5 crystals, which are transformed into more poly-aromatic coke species at the external surface, preventing the diffusion of reactants and products into and out of the H-ZSM-5 crystal. Furthermore, we were able to correlate the operando UV/Vis spectroscopy results observed during...

  5. Selective catalytic reduction of nitric oxide by ethylene over metal-modified ZSM-5- and {gamma}-Al{sub 2}O{sub 3}-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Eraenen, K; Kumar, N; Lindfors, L E [Aabo Akademi, Turku (Finland). Lab. of Industrial Chemistry

    1997-12-31

    Metal-modified ZSM-5 and {gamma}-Al{sub 2}O{sub 3} catalysts were tested in reduction of nitric oxide by ethylene. Different metals were introduced into the ZSM-5 catalyst by ion-exchange and by introduction of metals during the zeolite synthesis. To prepare bimetallic catalysts a combination of these methods was used. The {gamma}-Al{sub 2}O{sub 3} was impregnated with different metals by the incipient wetness technique and by adsorption. Activity measurements showed that the ZSM-5 based catalysts were more active than the {gamma}-Al{sub 2}O{sub 3} based catalysts. The highest conversion was obtained over a ZSM-5 catalyst prepared by introduction of Pd during synthesis of the zeolite and subsequently ion-exchanged with copper. (author)

  6. Selective catalytic reduction of nitric oxide by ethylene over metal-modified ZSM-5- and {gamma}-Al{sub 2}O{sub 3}-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Eraenen, K.; Kumar, N.; Lindfors, L.E. [Aabo Akademi, Turku (Finland). Lab. of Industrial Chemistry

    1996-12-31

    Metal-modified ZSM-5 and {gamma}-Al{sub 2}O{sub 3} catalysts were tested in reduction of nitric oxide by ethylene. Different metals were introduced into the ZSM-5 catalyst by ion-exchange and by introduction of metals during the zeolite synthesis. To prepare bimetallic catalysts a combination of these methods was used. The {gamma}-Al{sub 2}O{sub 3} was impregnated with different metals by the incipient wetness technique and by adsorption. Activity measurements showed that the ZSM-5 based catalysts were more active than the {gamma}-Al{sub 2}O{sub 3} based catalysts. The highest conversion was obtained over a ZSM-5 catalyst prepared by introduction of Pd during synthesis of the zeolite and subsequently ion-exchanged with copper. (author)

  7. Catalytic reduction of NO and N20 for CO on Co-ZSM-5

    International Nuclear Information System (INIS)

    Rios, Luis Alberto; Aristizabal, Gladys Liliana; Ruiz, Julio Fernando; Montes Consuelo

    1996-01-01

    Several catalysts with the help of ZSM-5 with Co were tested in the catalytic reduction of NO and N2O using CO like agent reducer and in presence of variable quantities of O2 The cobalt incorporated in the zeolite ZSM-5 for the methods of ionic exchange, impregnation and substitution. ZSM-5 exchanged with Co presented the highest conversions of NO (80% to 5OO oC), in presence of 3000 ppm of O2; When adding 25.700 ppm of O2 the conversion it diminished notably, that which shows an effect inhibitor of the O2. The substituted catalysts and impregnated they were less active for the reduction of the NO. With all the catalysts conversions of 70-90% were achieved for the N2O; Additionally, marked deactivation of the catalyst was not presented with the time

  8. H-ZSM-5 Zeolite Model Crystals: Structure-Diffusion-Activity Relationship in Methanol-to-Olefins Catalysis.

    Czech Academy of Sciences Publication Activity Database

    Losch, P.; Pinar, A.B.; Willinger, M.G.; Soukup, Karel; Chavan, S.; Vincent, B.; Pale, P.; Louis, B.

    2017-01-01

    Roč. 345, JAN 1 (2017), s. 11-23 ISSN 0021-9517 Grant - others:NRFL(LU) 5898454 Institutional support: RVO:67985858 Keywords : zeolite * methanol-to-olefins (MTO) * model catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 6.844, year: 2016

  9. Biomass catalytic fast pyrolysis over hierarchical ZSM-5 and Beta zeolites modified with Mg and Zn oxides

    Czech Academy of Sciences Publication Activity Database

    Hernando, H.; Moreno, I.; Fermoso, J.; Ochoa-Hernández, Cristina; Pizarro, P.; Coronado, J. M.; Čejka, Jiří; Serrano, D. P.

    2017-01-01

    Roč. 7, č. 3 (2017), s. 289-304 ISSN 2190-6815 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : catalytic fast pyrolysis * hierarchial zeolite * bio -oil upgrading Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  10. Self-templating synthesis of hollow spheres of zeolite ZSM-5 from spray-dried aluminosilicate precursor

    Czech Academy of Sciences Publication Activity Database

    Pashková, Veronika; Tokarová, V.; Brabec, Libor; Dědeček, Jiří

    2016-01-01

    Roč. 228, JUL 2016 (2016), s. 59-63 ISSN 1387-1811 R&D Projects: GA ČR GA15-13876S; GA MŠk LM2015073 Institutional support: RVO:61388955 Keywords : MFI * zeolite shells * template free synthesis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.615, year: 2016

  11. Theoretical study on the nitration of methane by acyl nitrate catalyzed by H-ZSM5 zeolite.

    Science.gov (United States)

    Silva, Alexander Martins; Nascimento, Marco Antonio Chaer

    2008-09-25

    A theoretical study on the nitration of methane by acyl nitrate catalyzed by HZSM-5 zeolite is reported. The zeolite was represented by a "double ring" 20T cluster. The calculations were performed at the DFT/X3LYP/6-31G** and MP2/6-31G** levels. The first step of the mechanism involves the protonation of the acyl nitrate by the zeolite and the formation of a nitronium-like ion. The reaction proceeds through a concerted step with the attack of the methane molecule by the nitronium-like ion and the simultaneous transfer of a proton from the methane molecule to the zeolite, thus reconstructing the acidic site. The activation energies for the first and second steps of this reaction are, respectively, 14.09 and 10.14 kcal/mol at X3LYP/6-31G** level and 16.68 and 13.85 kcal/mol at the MP2/6-31G**.

  12. H-ZSM-5 Zeolite Model Crystals: Structure-Diffusion-Activity Relationship in Methanol-to-Olefins Catalysis.

    Czech Academy of Sciences Publication Activity Database

    Losch, P.; Pinar, A.B.; Willinger, M.G.; Soukup, Karel; Chavan, S.; Vincent, B.; Pale, P.; Louis, B.

    2017-01-01

    Roč. 345, JAN 1 (2017), s. 11-23 ISSN 0021-9517 Grant - others:NRFL(LU) 5898454 Institutional support: RVO:67985858 Keywords : zeolite * methanol -to-olefins (MTO) * model catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 6.844, year: 2016

  13. Biomass catalytic fast pyrolysis over hierarchical ZSM-5 and Beta zeolites modified with Mg and Zn oxides

    Czech Academy of Sciences Publication Activity Database

    Hernando, H.; Moreno, I.; Fermoso, J.; Ochoa-Hernández, Cristina; Pizarro, P.; Coronado, J. M.; Čejka, Jiří; Serrano, D. P.

    2017-01-01

    Roč. 7, č. 3 (2017), s. 289-304 ISSN 2190-6815 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : catalytic fast pyrolysis * hierarchial zeolite * bio-oil upgrading Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  14. Spatial Distribution of Zeolite ZSM-5 within Catalyst Bodies Affects Selectivity and Stability of Methanol-to-Hydrocarbons Conversion

    NARCIS (Netherlands)

    Castaño, P.; Ruiz-Martinez, J.; Epelde, E.; Gayubo, A.G.; Weckhuysen, B.M.

    2013-01-01

    Solid acids, such as zeolites, are used as catalyst materials in a wide variety of important crude oil refinery, bulk chemical synthesis, and green processes. Examples include fluid catalytic cracking (FCC),[1] methanol-to-hydrocarbons (MTH) conversion,[ 2] plastic waste valorization,[3] and biomass

  15. FTIR study of the relation between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Isernia, Luis Fioravanti, E-mail: luis.isernia@gmail.com [Laboratorio de Tamices Moleculares, Universidad de Oriente - UO, Maturin, Monagas (Venezuela, Bolivarian Republic of)

    2013-11-01

    The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560-960 Degree-Sign C of the ZSM-5 catalyst (framework Si/Al ratio of 13), suggests an association between adsorbed molecular water and extra-framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Broensted and Lewis sites, when treatment temperature rises, with contradicts the frequently accepted mechanism of the transformation of two bridged Si-OH-Al groups for each Lewis site generated. The gradual conversion of the octahedral extra-framework aluminum (Lewis-associated) in polymeric species with low acidity is the most probable cause of this behavior. On the other hand, the apparent decline of the acid Broensted strength, with the increase in the temperature of the hydrothermal treatment, has two possible causes: a) the decreasing accessibility, of the pyridine molecular probe to bridged Si-OH-Al groups with the strongest Broensted acidity, inside the channels, and b) the gradual transformation of these groups into extra framework species of weak acidity. (author)

  16. Cu-ZSM-5 zeolite highly active in reduction of NO with decane - Effect of zeolite structural parameters on the catalyst performance

    Czech Academy of Sciences Publication Activity Database

    Čapek, Libor; Dědeček, Jiří; Wichterlová, Blanka; Cider, L.; Jobson, E.; Tokarová, V.

    2005-01-01

    Roč. 60, 3-4 (2005), s. 147-153 ISSN 0926-3373 R&D Projects: GA ČR GD203/03/H140; GA AV ČR 1ET400400413 Grant - others:European Union(XE) GR5D-CT2001-00595 Institutional research plan: CEZ:AV0Z40400503 Keywords : Cu-ZSM-5 * NO reduction * SCR-NOx * lean burn conditions * decane Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.809, year: 2005

  17. Effect of Metal Addition and Silica/Alumina Ratio of Zeolite on the Ethanol-to-Aromatics by Using Metal Supported ZSM-5 Catalyst

    International Nuclear Information System (INIS)

    Kim, Han-Gyu; Yang, Yoon-Cheol; Jeong, Kwang-Eun; Kim, Tae-Wan; Jeong, Soon-Yong; Kim, Chul-Ung; Jhung, Sung Hwa; Lee, Kwan-Young

    2013-01-01

    The catalytic conversion of ethanol to aromatic compounds ETA was studied over ZSM-5 heterogeneous catalysts. The effect of reaction temperature, weight hourly space velocity (WHSV), and addition of water and methanol, which are the potential impurities of bio-ethanol, on the catalytic performance was investigated in a fixed bed reactor. Commercial ZSM-5 catalysts having different Si/Al 2 ratios of 23 to 280 and modified ZSM-5 catalysts by addition of metal (Zn, La, Cu, and Ga) were used for the activity and stability tests in ETA reaction. The catalysts were characterized with ammonia temperature programmed desorption (NH3-TPD) and nitrogen adsorption-desorption techniques. The results of catalytic performance revealed that the optimal Si/Al 2 ratio of ZSM-5 is about 50-80 and the selectivity to aromatic compounds decreases in the order of Zn/La > Zn > La > Cu > Ga for the modified ZSM-5 catalysts. Among these catalysts from the ETA reaction, Zn-La/ZSM-5 showed the best catalytic performance for the ETA reaction. The selectivity to aromatic compounds was 72% initially and 56% after 30 h over the catalysts at reaction temperature of 437 .deg. C and WHSV of 0.8 h −1

  18. Construction of Bifunctional Co/H-ZSM-5 Catalysts for the Hydrodeoxygenation of Stearic Acid to Diesel-range Alkanes.

    Science.gov (United States)

    Wu, Guangjun; Zhang, Nan; Dai, Weili; Guan, Naijia; Li, Landong

    2018-04-27

    Bifunctional Co/H-ZSM-5 zeolites were prepared by surface organometallic chemistry grafting route, namely by the stoichiometric reaction between cobaltocene and the Brønsted acid sites in zeolites, and applied to the model reaction of stearic acid catalytic hydrodeoxygenation. Cobalt species existed in the form of isolated Co2+ ions at exchange positions after grafting, transformed to CoO species on the surface of zeolite and stabilized inside zeolite channels upon calcination in air, and finally reduced to metallic cobalt species of homogeneous clusters of ca. 1.5 nm by hydrogen. During this process, the Brønsted acid sites of H-ZSM-5 zeolites could be preserved with acid strength slightly reduced. The as-prepared bifunctional catalyst exhibited a ~16 times higher activity in stearic acid hydrodeoxygenation (2.11 gSAgcat-1h-1) than the reference catalyst (0.13 gSAgcat-1h-1) prepared by solid-state ion exchange, and a high C18/C17 ratio of ~24 was achieved as well. The remarkable hydrodeoxygenation performance of bifunctional Co/H-ZSM-5 could be explained from the effective synergy between the uniformed metallic cobalt clusters and the Brønsted acid sites in H-ZSM-5 zeolite. The simplified reaction network and kinetics of stearic acid hydrodeoxygenation catalyzed by the as-prepared bifunctional Co/H-ZSM-5 zeolites were also investigated. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tao; Shi, Juan; Liu, Jian, E-mail: liujian@cup.edu.cn; Wang, Daxi; Zhao, Zhen, E-mail: zhenzhao@cup.edu.cn; Cheng, Kai; Li, Jianmei

    2016-07-01

    Highlights: • The hydrothermal stability of Cu-ZSM-5 catalyst was enhanced after surface modification. • An inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer. • The contact between Si and Cu and Al atoms could form Si-O-Al and Si- O−Cu bonds. • The redox and acidity properties of Cu-ZSM-5-CLD-Aged catalyst were largely retained. • The adsorption and activation of NO and NH{sub 3} was almost unchanged over Cu-ZSM-5-CLD catalyst before and after hydrothermal treatment. - Abstract: The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH{sub 3}. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu{sup 2+} from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

  20. 1 - Aromatization of n-hexane and natural gasoline over ZSM-5 zeolite, 2- Wet catalytic oxidation of phenol on fixed bed of active carbon; 1 - Aromatisation de n-hexane et d'essence sur zeolithe ZSM-5, 2 - Oxydation catalytique en voie humide du phenol sur charbon actif

    Energy Technology Data Exchange (ETDEWEB)

    Suwanprasop, S.

    2005-04-15

    I - The production of aromatic hydrocarbons from n-hexane and natural gasoline over Pd loaded ZSM-5 zeolite in a tubular reactor was achieved under the suitable conditions at 400 deg. C, and 0.4 ml/min reactant feeding rate, employing ZSM-5 (0.5% Pd content) as a catalyst. Under these conditions, n-hexane and natural gasoline conversions were found to be 99.7% and 94.3%, respectively (with respective aromatic selectivity of 92.3% and 92.6%). II - Wet catalytic air oxidation of phenol over a commercial active carbon was studied in a three phase fixed bed reactor under mild temperature and oxygen partial pressure. Exit phenol concentration, COD, and intermediates were analysed. Oxidation of phenol was significantly improved when increasing operating temperature, oxygen partial pressure, and liquid space time, while up or down flow modes had only marginal effect. A complete model involving intrinsic kinetics and all mass transfer limitations gave convenient reactor simulation. (author)

  1. Paraselectivity and Formation of Aromatic Hydrocarbons over ZSM-5 Type Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Unneberg, E

    1997-12-31

    The zeolite ZSM-5, patented by Mobil Oil Corporation in 1972, is able to convert methanol to gasoline (MTG) and water. Due to the size of the channels, undesired hydrocarbons larger than C{sub 11} are not present in the mixture, and a high octane gasoline is obtained. This has aroused a great deal of interest in the ZSM-5. Rather than being concerned with energy considerations, this doctoral thesis describes syntheses of ZSM-5 and discusses the ZSM-5 as such and studies the possible paraselectivities in various reactions over the catalyst ZSM-5. 774 refs., 113 figs., 54 tabs.

  2. Paraselectivity and Formation of Aromatic Hydrocarbons over ZSM-5 Type Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Unneberg, E.

    1996-12-31

    The zeolite ZSM-5, patented by Mobil Oil Corporation in 1972, is able to convert methanol to gasoline (MTG) and water. Due to the size of the channels, undesired hydrocarbons larger than C{sub 11} are not present in the mixture, and a high octane gasoline is obtained. This has aroused a great deal of interest in the ZSM-5. Rather than being concerned with energy considerations, this doctoral thesis describes syntheses of ZSM-5 and discusses the ZSM-5 as such and studies the possible paraselectivities in various reactions over the catalyst ZSM-5. 774 refs., 113 figs., 54 tabs.

  3. Computational and fourier transform infrared spectroscopic studies on carbon monoxide adsorption on the zeolites Na-ZSM-5 and K-ZSM-5: Evidence of dual-cation sites

    Czech Academy of Sciences Publication Activity Database

    Areán, C. O.; Delgado, M. R.; Frolich, K.; Bulánek, R.; Pulido, Maria Angeles; Bibiloni, G. F.; Nachtigall, Petr

    2008-01-01

    Roč. 112, č. 12 (2008), s. 4658-4666 ISSN 1932-7447 R&D Projects: GA MŠk LC512; GA ČR GA203/06/0324 Grant - others:UIB(ES) MAT2005-05350 Institutional research plan: CEZ:AV0Z40550506 Keywords : zeolit * adsorpce * FTIR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.396, year: 2008

  4. Recovery of the heavy elements by NaY AND NaZSM-5 sorbant materials

    International Nuclear Information System (INIS)

    Nibou, D.; Lebail, S.

    1997-04-01

    Porous sorbants as zeolites have a several applications in differents fiels: industrial gas purification, catalysis, transformation hydrocarbures prosesses and exchange ions. The hiogh capacity to exchange their cations with those of aqueous solutions was known (1). Since the accession of synthetic zeolites, these silicates have invaded the market and the firstindustrial applications were in exchange field. Studies at Battelle Northwest in Rchland, Washington have shown that zeolites may be used in treatment of radioactive wastes (2). The used method for storing the isotopes is based on selective removal by ion exchange. Clinoptilolite, zeolite (modernite), NaA, and AW-500 have been used. In this context, the present work deals with the recovery of heavy metals like lead and uranium using some microporous materials. The obtained results show that NaY faujasite and NaZSM-5 of the FAU- and MFI-type structure respectively are very effective in removing these elements from waste water

  5. The effect of the pore structure of medium-pore zeolites on the dehydroisomerization of n-butane: A comparison of Pt-FER, Pt-TON and Pt-ZSM5

    NARCIS (Netherlands)

    Pirngruber, G.D.; Zinck, O.P.E.; Seshan, Kulathuiyer; Lercher, J.A.

    2000-01-01

    The catalytic dehydroisomerization of n-butane over Pt–ZSM5, Pt–TON, and Pt–FER was investigated. Pt–ZSM5 showed the highest yield and selectivity to isobutene. Most of the by-products of Pt–ZSM5 were formed by oligomerization/cracking of butene, while acid-catalyzed cracking and metal-catalyzed

  6. Quantitative 3D Fluorescence Imaging of Single Catalytic Turnovers Reveals Spatiotemporal Gradients in Reactivity of Zeolite H-ZSM-5 Crystals upon Steaming

    NARCIS (Netherlands)

    Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Hofmann, Jan P.|info:eu-repo/dai/nl/355351110; De Cremer, Gert; Kubarev, Alexey V.; Rohnke, Marcus; Meirer, Florian; Hofkens, Johan; Roeffaers, Maarten B. J.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2015-01-01

    Optimizing the number, distribution, and accessibility of Bronsted acid sites in zeolite-based catalysts is of a paramount importance to further improve their catalytic performance. However, it remains challenging to measure real-time changes in reactivity of single zeolite catalyst particles by

  7. Generación de mesoporosidad en zeolitas ZSM-5 sintetizadas en medio inorgánico

    Directory of Open Access Journals (Sweden)

    Carmen M. López

    2011-10-01

    Full Text Available In this work we presented a study over the generation of mesoporosity in ZSM-5 zeolites with ratio Si/Al of 10 and 35 synthesized in inorganic medium. A mesoporous phase with hexagonal arrangement that coexists with the zeolite ZSM-5 remnant, was obtained after alkaline treatment of zeolite followed by hydrothermal treatment in the presence of CTAB surfactant micelles. The acidity and catalytic activity of the zeolite ZSM-5 with higher relation Si/Al were kept after the treatment, whereas a notable decrease of these properties was obtained for the zeolite with minor relation Si/Al

  8. Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite

    Science.gov (United States)

    Jiang, Jinlong; Wu, Mei; Yang, Yong; Duanmu, Chuansong; Chen, Jing; Gu, Xu

    2017-10-01

    ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N2 adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.

  9. Effects of different level addition of zeolite ZSM-5 additive on quality and composition of the dry gas, LPG (Liquefied Petroleum Gas) and gasoline, produced in FCC (Fluid Catalytic Cracking); Efeito dos diferentes niveis de adicao de aditivos de ZSM-5 na qualidade e composicao do gas combustivel, GLP e gasolina produzidos em FCC

    Energy Technology Data Exchange (ETDEWEB)

    Bastiani, Raquel; Pimenta, Ricardo D.M.; Almeida, Marlon B.B.; Lau, Lam Y. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The effects of the addition of different level of ZSM-5 additives on different FCC catalysts formulations have been studied on laboratory scale FST (Fluidized Simulation Test). The main objective of the present work is to perform a qualitative identification of the main parameters of FCC catalyst which affect the ZSM-5 additives performance concerning quality and composition of Dry Gas, LPG and Gasoline. The product composition of each test was analyzed by PIANO groups separated by carbon number. The effect of ZSM-5 on products composition was evaluated. The results showed that the ZSM-5 additive cracks gasoline range olefins and isoparaffins into Dry Gas and LPG, favoring the formation of ethylene, propylene and butylenes, while the absolute yield of gasoline aromatics changes little. The aromatics fraction in gasoline, MON and RON numbers in gasoline increase. The ZSM-5 effectiveness is negatively affected by high levels of rare earth on FCC catalyst (RE-USY). Higher hydrogen transfer provides lower olefins (higher than C6) formation, which are the most reactive species for ZSM-5 cracking. (author)

  10. Preparation, characterization and antimicrobial property of ag+- nano Chitosan/ZSM-5: novel Hybrid Biocomposites

    Directory of Open Access Journals (Sweden)

    Maasoumeh Khatamiana

    2016-10-01

    Full Text Available Objective(s: Binary hybrids of chitosan-zeolite have many interesting applications in separation and bacteriostatic activity. Materials and Methods: Template free ZSM-5 zeolite was synthesized by hydrothermal method, physical hydrogels of nano chitosan in the colloidal domain were obtained in the absence of toxic organic solvent and then nano chitosan/ZSM-5 hybrid composites with nano chitosan contents of 0.35%, 3.5%, 35% wt.% were prepared. The as prepared hybrid composites were ion-exchanged with Ag cations. Results: XRD and FT-IR results revealed a good crystalinity of as synthesized template frees ZSM-5 with BET surface area of 307 m2g-1. Presence of chitosan in composites was confirmed by XRD patterns and FT-IR spectroscopic analysis, the chitosan content in composite was obtained with TG analysis. SEM analysis of composites shows that chitosan particles were dispersed within the nanometer scale. The antimicrobial activity of different samples was investigated and the results showed that the Ag+-exchanged samples have the highest antibacterial properties. Cancer cell line A549 cell line were cultured in designated medium treated with Ag+-exchanged samples at the concentration of 0.01 to 0.5 mg/ml. After 24 and 48 hours incubation, the efficacy of Ag+-exchanged samples to treat cancer cell lines were measured by means of cell viability test via MTT assay. Concentrations of 0.05 and 0.1 mg/ml of Ag+-exchanged samples induced a very low toxicity. Conclusion: These hybrid composite materials have potential applications on tissue engineering and antimicrobial food packaging.

  11. Preparação e caracterização de compósitos poliméricos baseados em amido termoplástico e materiais de alta área superficial: zeólita ZSM-5 e sílica coloidal Preparation and characterization of polymeric composites based on thermoplastic starch and high surface area materials: ZSM-5 zeolite and colloidal silica

    Directory of Open Access Journals (Sweden)

    Fábio Plotegher

    2013-01-01

    Full Text Available Foram produzidas amostras de amido termoplástico (TPS reforçadas com materiais de alta área superficial, com o intuito de verificar a variação nas propriedades do polímero, com especial enfoque na sua permeabilidade a vapor d'água. Foram utilizadas como carga a sílica coloidal (área superficial de 122,7 m²/g e uma zeólita do tipo ZSM-5, produzida em laboratório (área superficial de 261,3 m²/g, em teores de 2 a 10% em massa. Os resultados demonstraram que a adição de ambos os materiais melhorou as propriedades mecânicas do TPS, embora nos maiores teores houve redução da qualidade das interfaces e dessas propriedades, principalmente para a ZSM-5. Em todos os casos a introdução da carga inorgânica reduziu a permeabilidade ao vapor d'água em até 20% quando comparada à permeabilidade do TPS, porém a melhor dispersão da sílica coloidal na matriz permitiu as maiores reduções, apesar da área superficial inferior.Compositions of thermoplastic starch (TPS reinforced by high surface area materials were produced, intending to study the variation in polymer properties, focusing on the permeability to water vapor. Colloidal silica (surface area 122.7 m²/g and a ZSM-5 zeolite (surface area 261.3 m²/g were used, in loadings from 2 to 10% weight. The results demonstrated that the addition of both materials was favorable to the TPS mechanical properties, however in higher loadings the quality of polymer interfaces and these properties were negatively affected, especially for ZSM-5. In all the cases the inorganic particles reduced the permeability to water vapor in levels below 20% when compared to pure TPS, although the best dispersion of colloidal silica determined better reductions, despite its lower surface area.

  12. Active sites in Fe/ZSM-5 for nitrous oxide decomposition and benzene hydroxylation with nitrous oxide

    NARCIS (Netherlands)

    Sun, K.; Xia, H.; Feng, Z.; Santen, van R.A.; Hensen, E.J.M.; Li, Can

    2008-01-01

    The effect of the iron content and the pretreatment conditions of Fe/ZSM-5 catalysts on the Fe speciation and the catalytic activities in nitrous oxide decomposition and benzene hydroxylation with nitrous oxide has been investigated. Iron-containing ZSM-5 zeolites with varying iron content (Fe/Al =

  13. Cu-ZSM-5, Cu-ZSM-11, and Cu-ZSM-12 Catalysts for Direct NO Decomposition

    DEFF Research Database (Denmark)

    Kustova, Marina; Kustov, Arkadii; Christiansen, Sofie E.

    2006-01-01

    Cu-ZSM-5 has for many years been recognized as a unique catalyst for direct NO decomposition. Here, it is discovered that both Cu-ZSM-11 and Cu-ZSM-12 are about twice as active as Cu-ZSM-5. This difference is attributed to the active sites located almost exclusively in the straight zeolite pores...

  14. FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

    Directory of Open Access Journals (Sweden)

    Luis Fioravanti Isernia

    2013-01-01

    Full Text Available The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560‑960 °C of the ZSM‑5 catalyst (framework Si/Al ratio of 13, suggests an association between adsorbed molecular water and extra‑framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Brönsted and Lewis sites, when treatment temperature rises, with contradicts the frequently accepted mechanism of the transformation of two bridged Si‑OH‑Al groups for each Lewis site generated. The gradual conversion of the octahedral extra-framework aluminum (Lewis‑associated in polymeric species with low acidity is the most probable cause of this behavior. On the other hand, the apparent decline of the acid Brönsted strength, with the increase in the temperature of the hydrothermal treatment, has two possible causes: a the decreasing accessibility, of the pyridine molecular probe to bridged Si-OH-Al groups with the strongest Brönsted acidity, inside the channels, and b the gradual transformation of these groups into extra framework species of weak acidity.

  15. Kinetics and thermodynamic for sorption of arsenate by Lanthanum-exchanged zeolite

    International Nuclear Information System (INIS)

    Mohd Jelas Haron; Saiful Adli Masdan; Mohd Zobir Hussein; Zulkarnain Zainal; Anuar Kassim

    2007-01-01

    Zeolites are crystalline, hydrated aluminosilicate containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Since zeolites have permanent negative charges on their surfaces, they have no affinity for anions. However recent studies have shown that modification of zeolites with certain surfactants or metal cations yield sorbents with a strong affinity for many anions. In this paper, modification of zeolites (zeolite A, X and ZSM5) were performed by exchange of naturally occurring cations with lanthanum ion that forms low solubility arsenate salt. The exchanged zeolites were used to sorb arsenate from aqueous solution. Among parameters investigated were effect of pH, arsenate initial concentrations, contact time and temperature. The maximum exchanged capacity of La (III) ion was obtained when using solution with initial pH of 4. Zeolite X gives the highest La (III) exchanged capacity compared to other zeolites. The results showed that As (V) sorption by La-zeolites occurred at about pH 6.5 and increased as pH increased and reaching maximum at equilibrium pH about 7.8. On the other hand, almost no arsenate sorption occurred on un exchanged zeolites. This indicates that La (III) ion on the exchanged zeolites is taking part on the As(V) sorption via surface precipitation. The results also showed that the sorption capacities increased with increasing initial As (V) concentrations. The sorption followed Langmuir model with maximum sorption capacities of 0.41, 0.21 and 0.19 mmol/g at 25 degree Celsius for La exchanged zeolite X (La-ZX), La exchanged zeolite ZSM5 (La-ZSM) and La exchanged zeolite A (La-ZA), respectively. The amounts of sorption of As (V) by La exchanged zeolite increased as temperature increased from 25 to 70 degree Celsius indicating that the process is endothermic. The free energy changes ( ΔG degree) for the sorption at 25 degree Celsius were -10.25, -9.65 and -8.49 kJ/ mol for La-ZX, La-ZSM and La-ZA, respectively. The

  16. X-ray emission spectroscopy study of iron silicate catalyst FeZSM-5

    International Nuclear Information System (INIS)

    Csencsits, R.; Lyman, C.E.; Gronsky, R.

    1988-03-01

    Iron silicate analogs of the zeolite ZMS-5 may be directly synthesized from iron silicate gels in a manner which differs slightly from the alumino-silicate ZSM-5. The resultant white, crystalline iron silicate is referred to as FeZSM-5 in the as-synthesized form. Thermal treatment removes the organic crystal-directing agent and moves some of the framework iron into non-framework sites producing the calcined form of the molecular sieve FeZSM-5. Homogeneity in the distribution of catalytic iron throughout the particles is desired in an optimal catalyst. Distribution of the iron throughout the framework in the as-synthesized forms would affect the final distribution of catalytic iron in the calcined and steamed forms; thus, the iron distribution throughout the as-synthesized and calcined forms of FeZSM-5 were studied using the high spatial resolution on the analytical electron microscope. 7 refs., 3 figs

  17. Synthesis and characterization of ZSM-5 and calcined kaolin evaluation using the content of structure-directing

    International Nuclear Information System (INIS)

    Rodrigues, J.J.; Silva, V.J. da; Rodrigues, M.G.F.

    2012-01-01

    This study aims to evaluate the effect of the structure-directing content, tetrapropylammonium bromide, on the structural and morphological characteristics of ZSM-5 zeolite obtained using calcined kaolin as silicon and aluminum. The samples were characterized by XRD, EDX, SEM and Physics Adsorption N 2 . Trough X ray diffraction patterns was possible to observed the formation of the structure of ZSM-5 with intense peaks and well-defined characteristic of crystalline. The micrographs showed that the samples consist of agglomerates and/or aggregates of particles characteristic of the MFI structure typical of ZSM-5 zeolite. And through the adsorption-desorption isotherms physical N2 was possible to observe that the samples show hysteresis type I typical of microporous materials with specific surface areas of 218 and 222 m 2 /g. Therefore, the use of calcined kaolin to obtain ZSM-5 zeolite was effective. (author)

  18. Conversion of South African coal fly ash into high-purity ZSM-5 zeolite without additional source of silica or alumina and its application as a methanol-to-olefins catalyst

    CSIR Research Space (South Africa)

    Missengue, RNM

    2018-03-01

    Full Text Available Characteristics of ZSM-5 synthesized from H2SO4-treated coal fly ash and fused coal fly ash extracts are compared in this study. In the synthesis process, fused coal fly ash extract (without an additional silica source) was used in the synthesis...

  19. Partial oxidation of methane to methanol over catalyst ZSM-5 from coal fly ash and rice husk ash

    Directory of Open Access Journals (Sweden)

    Mirda Yanti Fusia

    2017-01-01

    Full Text Available Methane is one of the greenhouse gases that can be converted into liquid fuels such as methanol to retain most of the energy of methane and produce a cleaner environment. The conversion of methane to methanol using ZMS-5 represents a breakthrough in the utilization of methane. However, material sources for zeolite synthesis as catalyst usually are pro-analysis grade materials, which are expensive. Therefore, in this research, coal fly ash and rice husk ash were used as raw materials for mesoporous ZSM-5 zeolite synthesis. First, coal fly ash and rice husk were subjected to pre-treatment to extract silicate (SiO44− and aluminate (AlO45− and impurities separation. The ZSM-5 zeolite was synthesized through hydrothermal treatment using two types of templates. After ZSM-5 was synthesized, it was modified with Cobalt through impregnation method. The catalytic activity of both ZSM-5 and Co/ZSM-5 zeolites as heterogeneous catalysts in partial oxidation of methane were preliminary tested and compared with that commercial one. The result showed that the zeolite catalyst ZSM-5 from fly ash coal and rice husk ash has the potential to be used as catalysts in the partial oxidation of methane to methanol.

  20. Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts

    Directory of Open Access Journals (Sweden)

    Masakazu Iwamoto

    2015-12-01

    Full Text Available The aromatization of 2-octanol derived from castor oil as a byproduct in the formation of sebacic acid was investigated on various zeolite catalysts. Zn ion-exchanged MFI (ZSM-5 zeolites with small silica/alumina ratios and zinc contents of 0.5 to 2.0 wt. % were determined to exhibit good and stable activity for the reaction at 623 to 823 K. The yield of aromatics was 62% at 773 K and the space velocity 350 to 1400 h−1. The temperature and contact time dependences of the product distributions indicated the reaction pathways of 2-octanol→dehydration to 2-octene→decomposition to C5 and C3 compounds→further decomposition to small alkanes and alkenes→aromatization with dehydrogenation. Alcohols with carbon numbers of 5 to 8 exhibited similar distributions of products compared to 2-octanol, while corresponding carbonyl compounds demonstrated different reactivity.

  1. Catalytic properties of extraframework iron-containing species in ZSM-5 for N2O decomposition

    NARCIS (Netherlands)

    Li, G.; Pidko, E.A.; Filot, I.A.W.; Santen, van R.A.; Li, Can; Hensen, E.J.M.

    2013-01-01

    The reactivity of mononuclear and binuclear iron-containing complexes in ZSM-5 zeolite for catalytic N2O decomposition has been investigated by periodic DFT calculations and microkinetic modeling. On mononuclear sites, the activation of a first N2O molecule is favorable. The rate of catalytic N2O

  2. Nafion®/H-ZSM-5 composite membranes with superior performance for direct methanol fuel cells

    NARCIS (Netherlands)

    Yildirim, M.H.; Curos, Anna Roca; Motuzas, Julius; Motuzas, J.; Julbe, Anne; Stamatialis, Dimitrios; Wessling, Matthias

    2009-01-01

    Solution cast composite direct methanol fuel cell membranes (DEZ) based on DE2020 Nafion® dispersion and in-house prepared H-ZSM-5 zeolites with different Si/Al ratios were prepared and thoroughly characterized for direct methanol fuel cell (DMFC) applications. All composite membranes have indeed

  3. Location of Framework Al Atoms in the Channels of ZSM-5: Effect of the (Hydrothermal) Synthesis

    Czech Academy of Sciences Publication Activity Database

    Pashková, Veronika; Sklenák, Štěpán; Klein, Petr; Urbanová, Martina; Dědeček, Jiří

    2016-01-01

    Roč. 22, č. 12 (2016), s. 3937-3941 ISSN 1521-3765 R&D Projects: GA ČR GA15-13876S Institutional support: RVO:61388955 Keywords : ZSM-5 * synthesis * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry

  4. Thermogravimetry of alpha, omega-diaminoalkanes used in synthesizing zsm-5

    CSIR Research Space (South Africa)

    Howden, MG

    1993-04-01

    Full Text Available Thermogravimetry was determined on a series of alpha, omega-diaminoalkanes, in which the alkane chain contained from three to eight carbon atoms that were located in zeolite ZSM-5 during synthesis. Of the series, 1, 6-diaminohexane functions best...

  5. Ion exchange and hydrolysis reactions in zeolites

    International Nuclear Information System (INIS)

    Harjula, Risto.

    1993-09-01

    Among other uses, zeolites are efficient cation exchangers for aquatic pollution control. At present they they are mainly used in nuclear waste effluent treatment and in detergency. In the thesis, several ion exchange equilibria, important in these main fields of zeolite applications, were studied, with special emphasis on the formulation and calculation of the equilibria. The main interest was the development of thermodynamic formulations for the calculation of zeolite ion exchange equilibria in solutions of low or very low (trace) ion concentration, which are relevant for the removal of trace pollutants, such as radionuclides, from waste waters. Two groups of zeolite-cation systems were studied. First, binary Ca 2+ /Na + exchange in zeolites X and Y, which are of interest for detergency applications. Second, binary Cs + /Na + and Cs + /K + exchanges, and ternary Cs + /Na + /K + exchange in mordenite, which are important in nuclear waste effluent treatment. The thesis is based on five previous publications by author. (100 refs., 7 figs.)

  6. Synthesis of hierarchical porous materials with ZSM-5 structures via template-free sol–gel method

    Directory of Open Access Journals (Sweden)

    Wei Han et al

    2007-01-01

    Full Text Available Interests are focused on preparation of hierarchical porous materials with zeolite structures by using soft or rigid templates in order to solve diffusion and mass transfer limitations resulting from the small pore sizes of zeolites. Here we develop a convenient template-free sol–gel method to synthesize hierarchical porous materials with ZSM-5 structures. This method involves hydrothermal recrystallization of the xerogel converted from uniform ZSM-5 sol by a vacuum drying process. By utilizing this method we can manipulate the size of zeolite nanocrystals as building units of porous structures based on controlling temperature of recrystallization, consequently obtain hierarchical porous materials with different intercrystalline pore sizes and ZSM-5 structures.

  7. The Fabrication of Ga2O3/ZSM-5 Hollow Fibers for Efficient Catalytic Conversion of n-Butane into Light Olefins and Aromatics

    Directory of Open Access Journals (Sweden)

    Jing Han

    2016-01-01

    Full Text Available In this study, the dehydrogenation component of Ga2O3 was introduced into ZSM-5 nanocrystals to prepare Ga2O3/ZSM-5 hollow fiber-based bifunctional catalysts. The physicochemical features of as-prepared catalysts were characterized by means of XRD, BET, SEM, STEM, NH3-TPD, etc., and their performances for the catalytic conversion of n-butane to produce light olefins and aromatics were investigated. The results indicated that a very small amount of gallium can cause a marked enhancement in the catalytic activity of ZSM-5 because of the synergistic effect of the dehydrogenation and aromatization properties of Ga2O3 and the cracking function of ZSM-5. Compared with Ga2O3/ZSM-5 nanoparticles, the unique hierarchical macro-meso-microporosity of the as-prepared hollow fibers can effectively enlarge the bifunctionality by enhancing the accessibility of active sites and the diffusion. Consequently, Ga2O3/ZSM-5 hollow fibers show excellent catalytic conversion of n-butane, with the highest yield of light olefins plus aromatics at 600 °C by 87.6%, which is 56.3%, 24.6%, and 13.3% higher than that of ZSM-5, ZSM-5 zeolite fibers, and Ga2O3/ZSM-5, respectively.

  8. Chemical reactivity of cation-exchanged zeolites

    OpenAIRE

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed by Brønsted acid sites in the hydrogen forms of zeolites, the nature of chemical reactivity, and related, the structure of the metal-containing ions in cation-exchanged zeolites remains the subject...

  9. Decomposition of NO on Cu-loaded zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Escribano, A; Marquez-Alvarez, C; Rodriquez-Ramos, I; Fierro, J L.G. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain); Guerrero-Ruiz, A [Departamento de Quimica Inorganica, UNED, Madrid (Spain)

    1993-05-26

    Two copper ion-exchanged zeolites, Cu/NaY and Cu/NaZSM-5 have been studied by several techniques (TPR, TPD of NO, IR spectroscopy of adsorbed NO and XPS) and their catalytic activity for NO-decomposition have been determined under dynamic conditions. The results obtained here show that copper is stabilized as Cu[sup +] in Cu/NaZSM-5 after calcination in air at 673K, while in Cu/NaY the initial Cu[sup +]-ions are easier oxidized to Cu[sup 2+], this leading to a completely different catalytic behavior in the reaction of NO-decomposition. So, whereas the Cu/NaZSM-5 exhibits a high NO-conversion at the reaction temperatures (573 and 873K), the parent Cu/NaY zeolite becomes deactivated in the first stages of reaction.

  10. Perturbed angular correlation study of the ion exchange of indium into silicalite zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Ramallo-Lopez, J.M., E-mail: requejo@venus.fisica.unlp.edu.ar; Requejo, F.G., E-mail: requejo@venus.fisica.unlp.edu.ar; Renteria, M., E-mail: requejo@venus.fisica.unlp.edu.ar; Bibiloni, A.G. [UNLP, Programa TENAES (CONICET) and Departamento de Fisica, Faculdad Cs Ex (Argentina)], E-mail: requejo@venus.fisica.unlp.edu.ar; Miro, E.E. [UNL, INCAPE (CONICET) and Faculdad Ing. Quimica (Argentina)

    1999-09-15

    Two indium-containing silicalite zeolites (In/H-ZSM5) catalysts prepared by wet impregnation and ionic exchange were characterized by the Perturbed Angular Correlation (PAC) technique using {sup 111}In as probe to determine the nature of the indium species. Some of these species take part in the catalytic reaction of the selective reduction (SCR) of NO{sub x} with methane. PAC experiments were performed at 500 deg. C in air before and after reduction-reoxidation treatments on the catalysts in order to determine the origin of the different hyperfine interactions and then the degree of ionic exchange. Complementary catalytic activity characterizations were also performed.PAC experiments performed on the catalyst obtained by wet impregnation showed that all In-atoms form In{sub 2}O{sub 3} crystallites while almost 70% of In-atoms form In{sub 2}O{sub 3} in the catalyst obtained by ionic exchange. The PAC experiments of both catalysts performed after the reduction-reoxidation treatment revealed the presence of two hyperfine interactions, different from those corresponding to indium in In{sub 2}O{sub 3}. These hyperfine interactions should be associated to disperse In species responsible of the catalytic activity located in the ionic exchange-sites of the zeolites.

  11. Perturbed angular correlation study of the ion exchange of indium into silicalite zeolites

    International Nuclear Information System (INIS)

    Ramallo-Lopez, J.M.; Requejo, F.G.; Renteria, M.; Bibiloni, A.G.; Miro, E.E.

    1999-01-01

    Two indium-containing silicalite zeolites (In/H-ZSM5) catalysts prepared by wet impregnation and ionic exchange were characterized by the Perturbed Angular Correlation (PAC) technique using 111 In as probe to determine the nature of the indium species. Some of these species take part in the catalytic reaction of the selective reduction (SCR) of NO x with methane. PAC experiments were performed at 500 deg. C in air before and after reduction-reoxidation treatments on the catalysts in order to determine the origin of the different hyperfine interactions and then the degree of ionic exchange. Complementary catalytic activity characterizations were also performed.PAC experiments performed on the catalyst obtained by wet impregnation showed that all In-atoms form In 2 O 3 crystallites while almost 70% of In-atoms form In 2 O 3 in the catalyst obtained by ionic exchange. The PAC experiments of both catalysts performed after the reduction-reoxidation treatment revealed the presence of two hyperfine interactions, different from those corresponding to indium in In 2 O 3 . These hyperfine interactions should be associated to disperse In species responsible of the catalytic activity located in the ionic exchange-sites of the zeolites

  12. A MAS NMR and DRIFT study of the Ga species in Ga/H-ZSM5 catalysts and their effect on propane ammoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Pal, P. [Indian Inst. of Petroleum, Dehradun (India). Catalysis Division; Quartararo, J. [Liverpool Univ., Liverpool (United Kingdom). Leverhulme Centre for Innovative Catalysis, Dept. of Chemistry; Abd Hamid, S.B. [Malaya Univ., Postgraduate School, Bangunan (Malaysia); Derouane, E.G. [Algarve Univ., Faro (Portugal). Faculdade de Ciencias e Tecnologia; Vedrine, J.C. [Laboratoire de Physico-Chimie des Surface, Paris (France). Faculdade de Ciencias e Tecnologia; Magusin, P.C.M.M.; Anderson, B.G. [Eindhoven Univ. of Technology, Eindhoven (Netherlands). Schuit Institute of Catalysis

    2005-07-01

    This paper presents the results of a study that sought information about the nature and environment of the gallium (Ga) species in Ga/H-ZSM5 zeolites following H{sub 2}-O{sub 2} redox treatments applied during their activation by use of magic-angle spinning (MAS) {sup 71}Ga, {sup 27}Al, and {sup 29}Si NMR spectroscopy (Ga coordination) complemented by diffuse reflectance FT IR (DRIFT) spectroscopy (Bronsted acidity). This information was then correlated with their catalytic behavior for the ammoxidation of propane. Ga species were observed in several environments: octahedrally coordinated gallium in small Ga{sub 2}O{sub 3} particles at the external surface of the zeolite crystals; octahedrally coordinated gallium in GaO(OH) or related species; and tetrahedrally coordinated gallium in cationic-exchange positions inside the zeolite. Redox (H{sub 2}-O{sub 2}) cycles promote the migration of gallium from the GaO(OH) or Ga{sub 2}O{sub 3} species at the external surface of the zeolite crystals to cationic-exchange sites within the zeolite channels. It was concluded that the redox treatment had a beneficial effect on its catalytic performance for the ammoxidation of propane, which occurs via a bifunctional mechanism. The main product was acetonitrile at high gallium and aluminium contents. It was suggested that higher yields in acrylonitrile could be obtained through Ga-modified zeolites with a higher gallium and lower aluminium content. 22 refs., 1 tab., 6 figs.

  13. Studies of N{sub 2}0 adsorption and decomposition on Fe-ZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Benjamin R.; Reimer, Jeffrey A.; Bell, Alexis T.

    2002-03-08

    The interactions of N2O with H-ZSM-5 and Fe-ZSM-5 have been investigated using infrared spectroscopy and temperature-programmed reaction. Fe-ZSM-5 samples with Fe/Al ratios of 0.17 and 0.33 were prepared by solid-state exchange. It was determined that most of the iron in the samples of Fe-ZSM-5 is in the form of isolated cations, which have exchanged with Bronsted acid H+ in H-ZSM-5. The infrared spectrum of N2O adsorbed on H-ZSM-5 at 298 K exhibits bands at 2226 and 1308 cm-1 associated with vibrations of the N-N and N-O bonds, respectively. The positions of these bands relative to those seen in the gas phase suggest that N2O adsorbs through the nitrogen end of the molecule. The heat of N2O adsorption in H-ZSM-5 is estimated to be 5 kcal/mol. In the case of Fe-ZSM-5, additional infrared bands are observed at 2282 and 1344 cm-1 due to the interactions of N2O with the iron cations. Here too, the directions of the shifts in the vibrational features relative to those for gas-phase N2O suggest that the molecule adsorbs through its nitrogen end. The heat of adsorption of N2O on the Fe sites is estimated to be 16 kcal/mol. The extent of N2O adsorption on Fe depends on the oxidation state of Fe. The degree of N2O adsorption is higher following pretreatment of the sample in He or CO at 773 K, than following pretreatment in O2 or N2O at the same temperature. Temperature-programmed decomposition of N2O was performed on the Fe-ZSM-5 samples and revealed that N2O decomposes stoichiometrically to N2 and O2. A higher activity was observed if the catalysts were pretreated in He than if they were pretreated in N2O. For the He-pretreated samples, the activation energy for N2O decomposition was estimated to be 42 kcal/mol and the preexponential factor of the rate coefficient for this process was found to increase with Fe/Al ratio. This trend was attributed to the increasing auto reducibility of Fe3+ cations to Fe2+ cations with increasing Fe/Al ratio.

  14. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  15. N2O decomposition over Fe/ZSM-5: reversible generation of highly active cationic Fe species

    NARCIS (Netherlands)

    Zhu, Q.; Hensen, E.J.M.; Mojet, B.L.; Wolput, van J.H.M.C.; Santen, van R.A.

    2002-01-01

    Fe-oxide species in Fe/ZSM-5 (prepared by chemical vapor deposition of FeCl3)-active in N2O decomposition-react with zeolite protons during high temperature calcination to give highly active cationic Fe species, this transformation being reversible upon exposure to water vapor at lower temperature

  16. Characterization of UO22+ exchanged Y zeolite

    International Nuclear Information System (INIS)

    Olguin, M.T.; Bosch, P.; Bulbulian, S.; Duque, J.; Pomes, R.; Villafuerte-Castrejon, M.E.; Sansores, L.E.; Bosch, P.

    1997-01-01

    The present study discusses the incorporation of uranyl ion into Y-zeolite framework. The UO 2 2+ sorption was measured by neutron activation analyses. The Y-zeolite framework distorts in response to the cations present in the structure. Hence, depending on the amount and the location of the exchanged cations, the features of the X-ray diffraction pattern may vary. From the Rietveld analysis of these patterns, the positions occupied by the UO 2 2 + cations in the zeolite network were determined. (author)

  17. Xenon capture on silver-loaded zeolites: characterization of very strong adsorption sites

    International Nuclear Information System (INIS)

    Daniel, Cecile; Elbaraoui, Adnane; Aguado, Sonia; Schuurman, Yves; Farrusseng, David; Springuel-Huet, Marie-Anne; Nossov, Andrei; Fontaine, Jean-Pierre; Topin, Sylvain; Taffary, Thomas; Deliere, Ludovic

    2013-01-01

    The number and strength of adsorption sites for Xe in silver-modified zeolites are estimated from isotherm measurements at various temperatures over a broad range of pressure (from 1 ppm to atmospheric pressure). Fully and partially exchanged silver zeolites were synthesized starting from Na-ZSM-5(25), Na-ZSM-5(40), Na-Beta, NaX, and NaY. We have discovered that silver-modified zeolites may present one or two distinct adsorption sites depending on the nature of the material and silver loadings. The strongest adsorption sites are characterized by isosteric heat of adsorption in the order of -40 to -50 kJ.mol -1 . For Pentasil-type zeolites, we observe a linear 2:1 correlation between the total amount of silver and the number of strong sites. The highest concentration of strong sites is found for fully silver exchanged ZSM-5 (5.7 * 10 -4 mol/g), which presents the largest silver content for Pentasil-type zeolite. The equilibrium constant of Ag-ZSM-5 at low pressure is about 50 times larger than that of AgX. Qualitative correlations were established between Xe adsorption isotherms and Xe NMR signals. We show that Xe NMR could be used as a quantitative method for the characterization of the strength and of the number of strong Xe adsorption sites on silver-exchanged zeolites. The numbers of strong adsorption sites responsible for the Xe adsorption at 10-1000 ppm can be determined by the length of the plateau observed at low Xe uptake. In practice, our findings give guidelines for the discovery and optimization of silver-loaded zeolites for the capture of Xe at ppm levels. It appears that the amount of silver is a key parameter. Silver-modified ZSM-5 shows adsorption capacities 2-3 orders of magnitude larger than currently applied adsorbents for atmospheric Xe capture. (authors)

  18. One-Step Synthesis of Hierarchical ZSM-5 Using Cetyltrimethylammonium as Mesoporogen and Structure-Directing Agent

    OpenAIRE

    Meng, Lingqian; Mezari, Brahim; Goesten, Maarten G.; Hensen, Emiel J. M.

    2017-01-01

    Hierarchical ZSM-5 zeolite is hydrothermally synthesized in a single step with cetyltrimethylammonium (CTA) hydroxide acting as mesoporogen and structure-directing agent. Essential to this synthesis is the replacement of NaOH with KOH. An in-depth solid-state NMR study reveals that, after early electrostatic interaction between condensed silica and the head group of CTA, ZSM-5 crystallizes around the structure-directing agent. The crucial aspect of using KOH instead of NaOH lies in the faster...

  19. Nanocrystalline Hierarchical ZSM-5: An Efficient Catalyst for the Alkylation of Phenol with Cyclohexene.

    Science.gov (United States)

    Radhika, N P; Selvin, Rosilda; Kakkar, Rita; Roselin, L Selva

    2018-08-01

    In this paper, authors report the synthesis of nanocrystalline hierarchical zeolite ZSM-5 and its application as a heterogeneous catalyst in the alkylation of phenol with cyclohexene. The catalyst was synthesized by vacuum-concentration coupled hydrothermal technique in the presence of two templates. This synthetic route could successfully introduce pores of higher hierarchy in the zeolite ZSM-5 structure. Hierarchical ZSM-5 could catalyse effectively the industrially important reaction of cyclohexene with phenol. We ascribe the high efficiency of the catalyst to its conducive structural features such as nanoscale size, high surface area, presence of hierarchy of pores and existence of Lewis sites along with Brønsted acid sites. The effect of various reaction parameters like duration, catalyst amount, reactant mole ratio and temperature were assessed. Under optimum reaction conditions, the catalyst showed up to 65% selectivity towards the major product, cyclohexyl phenyl ether. There was no discernible decline in percent conversion or selectivity even when the catalyst was re-used for up to four runs. Kinetic studies were done through regression analysis and a mechanistic route based on LHHW model was suggested.

  20. Co-conversion of Ethane and Methanol into Higher Hydrocarbons over Ga/H-ZSM-5, Mo/H-ZSM-5 and Ga-Mo/H-ZSM-5

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Rovik, Anne; Christensen, Claus H.

    2009-01-01

    Ethane and methanol are converted simultaneously over Ga/H-ZSM-5, Mo/H-ZSM-5 and Ga-Mo/H-ZSM-5 to produce light olefins and aromatics. The presence of methanol in the reactant stream is intended to facilitate activation of ethane following literature reports on co-conversion of methane and methan...... and in the carbonaceous compounds deposited on the catalysts. This indicates that both reactants take part in the formation of the hydrocarbon pool, which is the origin of all products....

  1. Structure-activity relations for Ni-containing zeolites during NO reduction. II. Role of the chemical state of Ni

    NARCIS (Netherlands)

    Mosqueda Jimenez, B.I.; Jentys, A.; Seshan, Kulathuiyer; Lercher, J.A.

    2003-01-01

    The influence of the metal in Ni-containing zeolites used as catalysts for the reduction of NO with propane and propene was studied. In the fresh catalysts, Ni is located in ion exchange positions for Ni/MOR, Ni/ZSM-5, and Ni/MCM-22. The formation of carbonaceous deposits, the removal of Al from

  2. Location of Framework Al Atoms in the Channels of ZSM-5: Effect of the (Hydrothermal) Synthesis.

    Science.gov (United States)

    Pashkova, Veronika; Sklenak, Stepan; Klein, Petr; Urbanova, Martina; Dědeček, Jiří

    2016-03-14

    (27) Al 3Q MAS NMR and UV/Vis spectroscopy with bare Co(II) ions as probes of Al pairs in the zeolite framework were employed to analyze the location of framework Al atoms in the channel system of zeolite ZSM-5. Furthermore, the effect of Na(+) ions together with tetrapropylammonium cation (TPA(+)) in the ZSM-5 synthesis gel on the location of Al in the channel system was investigated. Zeolites prepared using exclusively TPA(+) as a structure-directing agent (i.e., in the absence of Na(+) ions) led to 55-90% of Al atoms located at the channel intersection, regardless the presence or absence of Al pairs [Al-O-(Si-O)2 -Al sequences in one ring] in the zeolite framework. The presence of Na(+) ions in the synthesis gel did not modify the Al location at the channel intersection (55-95% of Al atoms) and led only to changes in i) the distribution of framework Al atoms between Al pairs (decrease) and single isolated Al atoms (increase), and ii) the siting of Al in distinguishable framework tetrahedral sites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. TUNGSTOPHOSPHORIC ACID HETEROGENIZED ONTO NH4ZSM5 AS AN EFFICIENT AND RECYCLABLE CATALYST FOR THE PHOTOCATALYTIC DEGRADATION OF DYES

    Directory of Open Access Journals (Sweden)

    Candelaria Leal Marchena

    2015-05-01

    Full Text Available Materials based on tungstophosphoric acid (TPA immobilized on NH4ZSM5 zeolite were prepared by wet impregnation of the zeolite matrix with TPA aqueous solutions. Their concentration was varied in order to obtain TPA contents of 5%, 10%, 20%, and 30% w/w in the solid. The materials were characterized by N2 adsorption-desorption isotherms, XRD, FT-IR, 31P MAS-NMR, TGA-DSC, DRS-UV-Vis, and the acidic behavior was studied by potentiometric titration with n-butylamine. The BET surface area (SBET decreased when the TPA content was raised as a result of zeolite pore blocking. The X-ray diffraction patterns of the solids modified with TPA only presented the characteristic peaks of NH4ZSM5 zeolites, and an additional set of peaks assigned to the presence of (NH43PW12O40. According to the Fourier transform infrared and 31P magic angle spinning-nuclear magnetic resonance spectra, the main species present in the samples was the [PW12O40]3- anion, which was partially transformed into the [P2W21O71]6- anion during the synthesis and drying steps. The thermal stability of the NH4ZSM5TPA materials was similar to that of their parent zeolites. Moreover, the samples with the highest TPA content exhibited band gap energy values similar to those reported for TiO2. The immobilization of TPA on NH4ZSM5 zeolite allowed the obtention of catalysts with high photocatalytic activity in the degradation of methyl orange dye (MO in water, at 25 ºC. These can be reused at least three times without any significant decrease in degree of degradation.

  4. The nature of cationic adsorption sites in alkaline zeolites-single, dual and multiple cation sites

    Czech Academy of Sciences Publication Activity Database

    Nachtigall, P.; Delgado, M. R.; Nachtigallová, Dana; Arean, C. O.

    2012-01-01

    Roč. 14, č. 5 (2012), s. 1552-1569 ISSN 1463-9076 R&D Projects: GA ČR GA203/09/0143 Institutional research plan: CEZ:AV0Z40550506 Keywords : exchanged ZSM-5 zeolites * carbon-monoxide adsorption * low-temperature CO * solid-state NMR * high-silica zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.829, year: 2012

  5. Reduction of Nitrogen Oxides using zeolite catalysts exchanged with cobalt

    International Nuclear Information System (INIS)

    Garcia M, E.A.; Bustamante L, F.; Montes de C, C.

    1999-01-01

    The Selective Catalytic Reduction (SCR) of NOx by methane in excess oxygen was studied over several zeolite catalysts; namely cobalt loaded mordenite, ferrierite, SM-5 and the corresponding acid forms. When NO2 predominated n the NOx mixture the acid forms showed the highest N2 formation rates under dry conditions. Mordenite supported catalysts were the most active ones followed by ferrierite and ZSM-5. The most active Co-Mordenite catalyst was tested using a NOx mixture, containing mostly NO, under dry conditions and in the presence of water and SO2. The addition of 8 % water to the reaction mixture lead to a reversible deactivation, mainly at low temperatures. When the reaction mixture contained 60 ppm SO2, the N2 formation rate decreased about a half likely due to SO2 poisoning

  6. Sorption of methanol in alkali exchange zeolites

    NARCIS (Netherlands)

    Rep, M.; Rep, M.; Corma, Avelino; Palomares, A.E.; Palomares gimeno, A.E.; van Ommen, J.G.; Lefferts, Leonardus; Lercher, J.A.

    2000-01-01

    Metal cation methanol sorption complexes in MFI (ZSM5), MOR and X have been studied by in situ i.r. spectroscopy in order to understand the nature of interactions of methanol in the molecular sieve pores. The results show that (a) a freely vibrating hydroxy and methyl group of methanol exist on

  7. Multicomponent liquid ion exchange with chabazite zeolites

    International Nuclear Information System (INIS)

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

    1993-10-01

    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

  8. Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

    DEFF Research Database (Denmark)

    Giordanino, Filippo; Vennestrøm, Peter N. R.; Lundegaard, Lars Fahl

    2013-01-01

    concentration of reduced copper centres, i.e. isolated Cu+ ions located in different environments, able to form Cu+(N2), Cu+(CO)n (n = 1, 2, 3), and Cu+(NO)n (n = 1, 2) upon interaction with N2, CO and NO probe molecules, respectively. Low temperature FTIR, DRUV-Vis and EPR analysis on O2 activated samples...... an intense and finely structured d–d quadruplet, unique to Cu-SSZ-13, which is persistent under SCR conditions. This differs from the 22 700 cm−1 band of the mono(μ-oxo)dicopper species of the O2 activated Cu-ZSM-5, which disappears under SCR conditions. The EPR signal intensity sets Cu-β apart from...

  9. Effect of aluminium distribution in the framework of ZSM-5 on hydrocarbon transformation. Cracking of 1-butene

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Dědeček, Jiří; Gábová, Vendula; Wichterlová, Blanka; Spoto, G.; Bordiga, S.

    2008-01-01

    Roč. 254, č. 2 (2008), s. 180-189 ISSN 0021-9517 R&D Projects: GA AV ČR IAA4040308; GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : H-ZSM-5 * Al destribution * catalytic cracking * zeolite acidity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.167, year: 2008

  10. Characteristics of supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    Energy Technology Data Exchange (ETDEWEB)

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia)

    2010-02-15

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO{sub 2} as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO{sub 2}:ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m{sup 2}/g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  11. Characteristics of supported nano-TiO2/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    International Nuclear Information System (INIS)

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi; Mohamed, Abdul Rahman

    2010-01-01

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO 2 /ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO 2 as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO 2 :ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m 2 /g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  12. Adsorption of nicotine on different zeolite types, from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Stošić Dušan K.

    2007-01-01

    Full Text Available The plant alkaloid, nicotine, is a strongly toxic heterocyclic compound: the lethal dose for an adult human being (40-60 mg is importantly lower in comparison with the other known poisons such as arsenic or strychni­ne. Cigarettes represent "the most toxic and addictive form of nicotine". Besides the negative effects of nicotine on public health produced by self-administration, recently another potentially very dangerous effect has been recognized: because of its miscibility with water, nicotine can be found in industrial wastewaters, and consequently, in groundwater. Therefore, the problem of nicotine removal from aqueous solutions has became an interesting topic. In this work, the removal of nicotine has been probed by adsorption on solid materials. Adsorption of nicotine on different zeolites (clinoptilolite, ZSM-5 and β zeolite and on activated carbon was investigated from aqueous solutions, at 298 K. The obtained results are presented as adsorption isotherms: the amount of adsorbed nicotine as a function of equilibrium concentration. These data were obtained from the residual amount of nicotine in the aqueous phase, by the use of UV spectroscopy. The highest amounts of adsorbed nicotine was found for activated carbon and p zeolite (~ mmol·g-1. The attempt to modify the adsorption properties of ZSM-5 zeolite has been also done: ZSM-5 was modified by ion-exchange with VIII group metal (Cu2+ and Fe3+. In addition, the adsorption of nicotine on ZSM-5 zeolite with different Si/Al ratios has been done. It has been noticed that ion-exchange did not improve the adsorption possibilities, while the adsorption was importantly lower in the case of higher silicon content in ZMS-5 structure. 13C NMR spectra were collected for suspensions formed of solid adsorbent and aqueous solution of nicotine; in this way, the part of nicotine molecule which is most probably connected with the adsorbent was recognized.

  13. The Catalytic Conversion of Thiophenes over Large H-ZSM-5 Crystals: An X-Ray, UV/Vis, and Fluorescence Microspectroscopic Study

    NARCIS (Netherlands)

    Kox, M.H.F.; Mijovilovich, A.E.; S ättler, J.J.H.B.; Stavitski, I.; Weckhuysen, B.M.

    2013-01-01

    X-ray absorption, UV/Vis, and fluorescence microspectroscopy have been used to characterize the catalytic conversion of thiophene derivatives within the micropores of an individual H-ZSM-5 zeolite crystal. Space-resolved information into the Si/ Al ratios and sulfur content was provided by X-ray

  14. Exchange of deuterium with hydrogen of zeolite catalyst surface

    International Nuclear Information System (INIS)

    Minachev, Kh.M.; Dmitriev, R.V.; Penchev, V.; Kanazirev, V.; Minchev, Kh.; Kasimov, Ch.K.; Bylgarska Akademiya na Naukite, Sofia. Inst. za Obshta i Organichna Khimiya; AN Azerbajdzhanskoj SSR, Baku. Inst. Neftekhimicheskikh Protsessov)

    1981-01-01

    Isotope heteromolecular exchange of hydrogen on the reduced nickel-containing zeolites takes places at the temperatures above 100 deg and it is controlled by activated hydrogen transfer from metal particles on the substrate surface. High-temperature redox treatment of nickel-containing zeolites results in the formation of large nickel crystallites on zeolite external faces. The rest part of nickel remains in zeolite pores and conditions a high promoting effect in the exchange reaction. Catalytic activity of reduced zeolites NiCaNaY in toluene disproportionation increases considerably only in the cases when nickel is introduced into zeolite by means of ion exchange. Close spatial location of nickel particles and OH groups promotes the procedure of both isotope exchange and disproportionation of toluene [ru

  15. Energetics of sodium-calcium exchanged zeolite A.

    Science.gov (United States)

    Sun, H; Wu, D; Guo, X; Shen, B; Navrotsky, A

    2015-05-07

    A series of calcium-exchanged zeolite A samples with different degrees of exchange were prepared. They were characterized by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). High temperature oxide melt drop solution calorimetry measured the formation enthalpies of hydrated zeolites CaNa-A from constituent oxides. The water content is a linear function of the degree of exchange, ranging from 20.54% for Na-A to 23.77% for 97.9% CaNa-A. The enthalpies of formation (from oxides) at 25 °C are -74.50 ± 1.21 kJ mol(-1) TO2 for hydrated zeolite Na-A and -30.79 ± 1.64 kJ mol(-1) TO2 for hydrated zeolite 97.9% CaNa-A. Dehydration enthalpies obtained from differential scanning calorimetry are 32.0 kJ mol(-1) H2O for hydrated zeolite Na-A and 20.5 kJ mol(-1) H2O for hydrated zeolite 97.9% CaNa-A. Enthalpies of formation of Ca-exchanged zeolites A are less exothermic than for zeolite Na-A. A linear relationship between the formation enthalpy and the extent of calcium substitution was observed. The energetic effect of Ca-exchange on zeolite A is discussed with an emphasis on the complex interactions between the zeolite framework, cations, and water.

  16. Ion Exchange Properties of Georgian Natural Zeolites

    Directory of Open Access Journals (Sweden)

    Vladimer Tsitsishvili

    2017-06-01

    Full Text Available Ion-exchange properties of natural zeolites of Georgia with a relatively low Si/Al ratio have been studied: analcimes are characterized by selectivity series: Na+>K+>Ag+>NH4+>Ca+2>Sr+2>Li+; for phillipsites selectivity sequences are different for calcium- and potassium forms; selectivity sequence for scolecite is: Sr+2>Ba+2>Rb+>Ca+2>Cs+>K+>NH4+>Na+>Mg+2>Li+>Cd+2>Cu+2> Mn+2> Zn+2>Co+2>Ni+2.

  17. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

    International Nuclear Information System (INIS)

    Barnabas, M.V.; Trifunac, A.D.

    1994-01-01

    Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations

  18. Structure and critical function of Fe and acid sites in Fe-ZSM-5 in propane oxidative dehydrogenation with N2O and N2O decomposition

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Sathu, Naveen Kumar; Tabor, Edyta; Wichterlová, Blanka; Sklenák, Štěpán; Sobalík, Zdeněk

    2013-01-01

    Roč. 299, MAR 2013 (2013), s. 188-203 ISSN 0021-9517 R&D Projects: GA ČR GAP106/11/0624; GA ČR GA203/09/1627 Institutional support: RVO:61388955 Keywords : Fe-ZSM-5 zeolite * Structure of Fe species * Steamed Fe-zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.073, year: 2013

  19. Oxidation of cyclohexane catalyzed by metal-ion-exchanged zeolites.

    Science.gov (United States)

    Sökmen, Ilkay; Sevin, Fatma

    2003-08-01

    The ion-exchange rates and capacities of the zeolite NaY for the Cu(II), Co(II), and Pb(II) metal ions were investigated. Ion-exchange equilibria were achieved in approximately 72 h for all the metal ions. The maximum ion exchange of metal ions into the zeolite was found to be 120 mg Pb(II), 110 mg Cu(II), and 100 mg Co(II) per gram of zeolite NaY. It is observed that the exchange capacity of a zeolite varies with the exchanged metal ion and the amount of metal ions exchanged into zeolite decreases in the sequence Pb(II) > Cu(II) > Co(II). Application of the metal-ion-exchanged zeolites in oxidation of cyclohexane in liquid phase with visible light was examined and it is observed that the order of reactivity of the zeolites for the conversion of cyclohexane to cyclohexanone and cyclohexanol is CuY > CoY > PbY. It is found that conversion increases by increase of the empty active sites of a zeolite and the formation of cyclohexanol is favored initially, but the cyclohexanol is subsequently converted to cyclohexanone.

  20. Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation

    KAUST Repository

    Imran, Ali; Bramer, Eddy; Seshan, Kulathuiyer; Brem, Gerrit

    2016-01-01

    -staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low

  1. Effect of Steam Deactivation Severity of ZSM-5 Additives on LPG Olefins Production in the FCC Process.

    Science.gov (United States)

    Gusev, Andrey A; Psarras, Antonios C; Triantafyllidis, Konstantinos S; Lappas, Angelos A; Diddams, Paul A

    2017-10-21

    ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC) process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam), FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-5 in Olefins boosting additives) are prone to dealumination and partial structural collapse, thereby losing activity, micropore surface area, and undergoing changes in selectivity. Fresh catalyst and additives are added at appropriate respective levels to the FCC unit on a daily basis to maintain overall targeted steady-state (equilibrated) activity and selectivity. To mimic this process under accelerated laboratory conditions, a commercial P/ZSM-5 additive was hydrothermally equilibrated via a steaming process at two temperatures: 788 °C and 815 °C to simulate moderate and more severe equilibration industrial conditions, respectively. n -Dodecane was used as probe molecule and feed for micro-activity cracking testing at 560 °C to determine the activity and product selectivity of fresh and equilibrated P-doped ZSM-5 additives. The fresh/calcined P/ZSM-5 additive was very active in C 12 cracking while steaming limited its activity, i.e., at catalyst-to-feed (C/F) ratio of 1, about 70% and 30% conversion was obtained with the fresh and steamed additives, respectively. A greater activity drop was observed upon increasing the hydrothermal deactivation severity due to gradual decrease of total acidity and microporosity of the additives. However, this change in severity did not result in any selectivity changes for the LPG (liquefied petroleum gas) olefins as the nature (Brønsted-to-Lewis ratio) of the acid/active sites was not significantly altered upon steaming. Steam deactivation of ZSM-5 had also no significant effect on aromatics formation which was enhanced at higher

  2. Effect of Steam Deactivation Severity of ZSM-5 Additives on LPG Olefins Production in the FCC Process

    Directory of Open Access Journals (Sweden)

    Andrey A. Gusev

    2017-10-01

    Full Text Available ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam, FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-5 in Olefins boosting additives are prone to dealumination and partial structural collapse, thereby losing activity, micropore surface area, and undergoing changes in selectivity. Fresh catalyst and additives are added at appropriate respective levels to the FCC unit on a daily basis to maintain overall targeted steady-state (equilibrated activity and selectivity. To mimic this process under accelerated laboratory conditions, a commercial P/ZSM-5 additive was hydrothermally equilibrated via a steaming process at two temperatures: 788 °C and 815 °C to simulate moderate and more severe equilibration industrial conditions, respectively. n-Dodecane was used as probe molecule and feed for micro-activity cracking testing at 560 °C to determine the activity and product selectivity of fresh and equilibrated P-doped ZSM-5 additives. The fresh/calcined P/ZSM-5 additive was very active in C12 cracking while steaming limited its activity, i.e., at catalyst-to-feed (C/F ratio of 1, about 70% and 30% conversion was obtained with the fresh and steamed additives, respectively. A greater activity drop was observed upon increasing the hydrothermal deactivation severity due to gradual decrease of total acidity and microporosity of the additives. However, this change in severity did not result in any selectivity changes for the LPG (liquefied petroleum gas olefins as the nature (Brønsted-to-Lewis ratio of the acid/active sites was not significantly altered upon steaming. Steam deactivation of ZSM-5 had also no significant effect on aromatics formation which was enhanced at

  3. Aluminium distribution in ZSM-5 revisited: The role of Al–Al interactions

    International Nuclear Information System (INIS)

    Ruiz-Salvador, A. Rabdel; Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W.

    2013-01-01

    We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al–Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si 94 Al 2 O 192 cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g., the T14 site), and the Al–Al interaction, which at this Si/Al maximises Al–Al distances in general agreement with Dempsey’s rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al–Al distances. - Graphical abstract: Role of Al–Al interactions in high silica ZSM-5 is shown to be anisotropic in nature and not dependent solely on Coulombic interactions. Highlights: ► Si–Al distribution in ZSM-5 is revisited, stressing the role of the Al–Al interaction. ► Coulomb interactions are not the key factors controlling the Al siting. ► Anisotropy of the framework is identified as a source of departure from Dempsey’s rule.

  4. Synthesis of 4A zeolites from kaolin for obtaining 5A zeolites through ionic exchange for adsorption of arsenic

    International Nuclear Information System (INIS)

    Resmini Melo, Carolina; Gracher Riella, Humberto; Cabral Kuhnen, Nivaldo; Angioletto, Elidio; Melo, Aline Resmini; Bernardin, Adriano Michael; Rocha, Marcio Roberto da; Silva, Luciano da

    2012-01-01

    Highlights: ► We synthesize 4A zeolite from kaolin by hydrothermal reaction with sodium hydroxide. ► The 4A zeolite synthesized underwent ion exchange with calcium ions, with different parameters, to obtain 5A zeolites. ► The best 4A zeolite obtained was used as adsorbent material for arsenic ions. ► The results showed that the 5A zeolite material obtained is a good adsorber of heavy ions. - Abstract: The synthesis of adsorbing zeolite materials requires fine control of the processing variables. There are distinct process variable settings for obtaining specific desired types of zeolites. The intent of this study was to obtain 4A zeolites from kaolin in order to obtain 5A zeolites through ionic exchange with the previously synthesized zeolite. This zeolite 5A was used as an adsorbent for arsenic ions. The results obtained were satisfactory.

  5. Deactivation of La-Fe-ZSM-5 catalyst for selective catalytic reduction of NO with NH{sup 3}. Field study results

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Gongshin; Yang, Ralph T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Chang, Ramsay; Cardoso, Sylvio [Air Pollution Control, Power Generation, Electric Power Research Institute, Palo Alto, CA 94304-1395 (United States); Smith, Randall A. [Fossil Energy Research Corporation, Laguna Hills, CA 92653 (United States)

    2004-11-08

    Results are summarized for a study on the effects of poisons on the La-Fe-ZSM-5 catalyst activity for the selective catalytic reduction of NO by ammonia. The deactivation of La-Fe-ZSM-5 honeycombs was studied in field tests. A honeycomb catalyst containing 25%La-Fe-ZSM-5 had an overall activity similar to that of a commercial vanadia honeycomb catalyst. Long-term activity test results show that the 25%La-Fe-ZSM-5 catalyst activity decreased to 50% after 300h and 25% after 1769h of on-stream flue gas exposure. The deactivation is correlated to the amounts of poisons deposited on the catalyst. Poisons include alkali and alkaline earth metals, As and Hg. Hg was found to be ion-exchanged from HgCl{sup 2} to form Hg-ZSM-5, and Hg was found to be among the strongest poisons. The poisoning effects of these elements appeared to be additive. Thus, from the chemical analysis of the deactivated catalyst, the deactivation of Fe-ZSM-5 can be predicted.

  6. Metal oxide blended ZSM-5 nanocomposites as ethanol sensors

    Indian Academy of Sciences (India)

    Framework of ZSM-5 structure consists of intersecting ... ges quality monitoring, environmental monitoring, indoor air quality and .... metric stretching vibrations of Si–O group [22]. ..... [17] Cheng Y, Liao R H, Li J S, Sun X Y and Wang L J 2008.

  7. Aromatic Transformations Over Mesoporous ZSM-5: Advantages and Disadvantages

    Czech Academy of Sciences Publication Activity Database

    Musilová, Zuzana; Žilková, Naděžda; Park, S.-E.; Čejka, Jiří

    2010-01-01

    Roč. 53, 19-20 (2010), s. 1457-1469 ISSN 1022-5528 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous ZSM-5 * alkylation * disproportionation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.359, year: 2010

  8. CoX zeolites and their exchange with deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Novakova, J; Kubelkova, L; Jiru, P [Ceskoslovenska Akademie Ved, Prague. Ustav Fyzikalni Chemie

    1976-04-01

    An analysis of the gaseous phase using a mass spectrometer and analysis of the solid phase using an infrared spectrophotometer was made to investigate the deuterium exchange with hydrogen mostly bound in hydroxyl groups of zeolites CoX(21 and 47%) and NaX. It was found that with the increasing amount of cobalt ions the number of exchangeable hydrogens of the zeolite increases; the respective types of the hydrogen are discussed with respect to the particular dehydration temperatures. The rate of the D/sub 2/+OH exchange is substantially faster with the CoX than with the NaX zeolite, and exhibits a decrease with increasing dehydration. On the other hand, the rate of D/sub 2/+H/sub 2/ exchange without zeolite hydrogen incorporation, catalyzed by CoX zeolites, increases with increasing dehydration. The increased activation of gaseous hydrogen molecules is related to the presence in the zeolite of cobalt ions whose properties change during dehydration with the change in their environment. Hydroxyl groups of the CoX zeolites are not equivalent during the exchange; the hydroxyl hydrogens of the 3740 cm/sup -1/ band are exchanged more slowly than are the other hydrogens.

  9. CoX zeolites and their exchange with deuterium

    International Nuclear Information System (INIS)

    Novakova, J.; Kubelkova, L.; Jiru, P.

    1976-01-01

    An analysis of the gaseous phase using a mass spectrometer and analysis of the solid phase using an infrared spectrophotometer was made to investigate the deuterium exchange with hydrogen mostly bound in hydroxyl groups of zeolites CoX(21 and 47%) and NaX. It was found that with the increasing amount of cobalt ions the number of exchangeable hydrogens of the zeolite increases; the respective types of the hydrogen are discussed with respect to the particular dehydration temperatures. The rate of the D 2 +OH exchange is substantially faster with the CoX than with the NaX zeolite, and exhibits a decrease with increasing dehydration. On the other hand, the rate of D 2 +H 2 exchange without zeolite hydrogen incorporation, catalyzed by CoX zeolites, increases with increasing dehydration. The increased activation of gaseous hydrogen molecules is related to the presence in the zeolite of cobalt ions whose properties change during dehydration with the change in their environment. Hydroxyl groups of the CoX zeolites are not equivalent during the exchange; the hydroxyl hydrogens of the 3740 cm -1 band are exchanged more slowly than are the other hydrogens. (author)

  10. Synthesis of Nd-doped ZSM-5 and its application to treating slightly polluted water

    Directory of Open Access Journals (Sweden)

    Mang Lu

    2018-03-01

    Full Text Available In this study, ZSM-5 zeolite was synthesized using diatomaceous mud as the raw material, and then doped with different amounts of Nd2O3. The orthogonal experiments were performed to investigate the influence of Nd:Si molar ratio, zeolite dosage, contact time, solution pH and temperature on the removal of humic acid (HA. The removal of HA was comprehensively evaluated by chemical oxygen demand (COD, UV254 and UV410 of the solution. The results demonstrate that solution pH and zeolite dosage are the two most important factors influencing HA adsorption. The optimum experimental conditions were determined to be: 35 °C, Nd:Si molar ratio of 1:100, 2.0 g/L zeolite, pH 4 and 50 min contact time. Under these conditions, the removal efficiencies of UV254, UV410 and COD are 82.70%, 76.00% and 82.10%, respectively, corresponding to a comprehensive removal of 81.02%.

  11. Investigation of thermodynamic parameters of cetyl pyridinium bromide sorption onto ZSM-5 and natural clinoptilolite

    International Nuclear Information System (INIS)

    Ghiaci, M.; Kia, R.; Kalbasi, R.J.

    2004-01-01

    A study was undertaken to determine the influence of temperature and surfactant concentration on the adsorption of cetyl pyridinium bromide on two ZSM-5 zeolites, and on natural clinoptilolite. The effect of temperature on adsorption and thermodynamic properties was investigated by making measurements at (297, 303, 307, 313) K. The results show that the calculated curves from the general isotherm equation can represent the experimental data very well up to T=313 K. Based on the calculation of the thermodynamics of adsorption, it is evident that the principle contribution to the ΔG compfn hm of negative value is the large positive value of ΔS compfn hm (36 to 52 J · mol -1 ), whereas ΔH compfn hm is positive and in the range of 1 to 7 kJ · mol -1 . Therefore, similar to the micellisation in bulk solution, the second step of surfactant adsorption is an entropy-driven process

  12. Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Ahmed K. Aboul-Gheit

    2012-12-01

    Full Text Available H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm and the smallest pores (0.4–1.7 nm. The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give Ea and ΔS∗ values compatible with the characterization data of the catalysts.

  13. NOx reduction over metal-ion exchanged novel zeolite under lean conditions. Activity and hydrothermal stability

    International Nuclear Information System (INIS)

    Subbiah, Ayyappan; Gujar, Amit; Price, Geoffrey L.; Cho, Byong K.; Blint, Richard J.; Yie, Jae E.

    2003-01-01

    Zeolite SUZ-4 was synthesized and tested for its hydrothermal stability using a standard aging procedure coupled with NMR spectroscopy, and was identified as a promising support for lean-NO x catalysts for high temperature applications. Various metals such as Cu, Ag, Fe, Co were ion exchanged onto the SUZ-4 zeolite, and their catalytic activity for NO/NO x conversion was measured in the presence of excess oxygen using ethylene as the reducing agent. Among the metal-ions exchanged, copper proved to be the best metal cation for lean-NO x catalysis with the optimum level of exchange at 29-42%. The optimized, fresh Cu/SUZ-4 catalyst achieved 70-80% of NO/NO x conversion activity over a wide range of temperature from 350 to 600C with the maximum conversion temperature at 450C. The presence of H 2 O and SO 2 reduced the NO/NO x conversion by about 30% of the fresh Cu/SUZ-4 catalyst due possibly to the blocking of active sites for NO/NO x adsorption. Substitution of gasoline vapor for ethylene as the reductant improved the NO x reduction activity of the fresh Cu/SUZ-4 catalyst at high temperatures above 350C. Aging the Cu/SUZ-4 catalyst resulted in a slight shift of activity profile toward higher temperatures, yielding an increase of NO conversion by 16% and a decrease of NO x conversion by 15% at 525C. The effect of H 2 O and SO 2 on the aged catalyst was to reduce the NO activity by 20% and NO x activity by 30% at 500C. The effect of space velocity change was not significant except in the low temperature range where the reaction light-off occurs. Adsorption/desorption measurements indicate that aging Cu/SUZ-4 results in partial migration/agglomeration of Cu particles in the pores thereby reducing the NO/NO x activity. Overall, the NO x conversion efficiency of Cu/SUZ-4, for both fresh and aged, is much better than the benchmark Cu/ZSM-5 in the presence of H 2 O and/or SO 2

  14. CONVERSION OF (±-CITRONELLAL AND ITS DERIVATIVES TO (--MENTHOL USING BIFUNCTIONAL NICKEL ZEOLITE CATALYSTS

    Directory of Open Access Journals (Sweden)

    Indri Badria Adilina

    2015-06-01

    Full Text Available (±-Citronellal and its derivatives were converted to (--menthol by a one-pot reaction system using zeolite based nickel catalysts. The catalysts were prepared by immobilization of nickel on natural zeolite (NZ or synthetic zeolite (ZSM-5 by a simple cation exchange method. Calcination and hydrogen treatment procedures were able to significantly increase the surface area and pore volume of NZ based catalysts whereas negligible changes in the properties were observed for that of ZSM-5. Catalytic reactions were carried out at 70ºC by stirring the mixture in the air for cyclization of (±-citronellal to (±-isopulegol followed by hydrogenation towards the desired (--menthol at 2 Mpa of H2 pressure. The Ni/NZ catalyst was able to convert a (±-citronellal derivative yielding 9% (--menthol (36% selectivity with conversion up to 24%, whereas Ni/ZSM5 catalyst directly converted 65% (±-citronellal to give 4% menthol (6% selectivity. These zeolite based catalysts are therefore potential materials for the conversion of biomass feed stock to value-added chemicals.

  15. Ion exchange properties of zeolite-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Koval' chuk, L V; Takhtarova, G N; Topchieva, K V [Moskovskii Gosudarstvennyi Univ. (USSR). Kafedra Fizicheskoi Khimii

    1975-03-01

    In the paper the reaction of sodium ion exchange for ammonium cations, cations of calcium and lanthanum in the amorphous aluminium silicate Na/sub 0,856/(AlO/sub 2/)(SiO/sub 2/)/sub 9,831/, zeolite Na/sub 1/(AlO/sub 2/)(SiO/sub 2/)/sub 2,33/ and zeolite containing catalyst Na/sub 1,09/(AlO/sub 2/)(SiOsub(2))/sub 7,93/ were studied; exchange isotherms of sodium for ammonium, calcium and lanthanium are presented. Results received in the study indicate high selectivity of zeolite for calcium and lanthanum cations in comparison with amorphous aluminium silicate and also display electroselectivity effect. The highest separation coefficient takes place for lanthanum in the sodium exchange in zeolite.

  16. Effect of ZSM-5 on the production of reformulated gasoline. Comparison between FCC pilot plant and commercial results

    International Nuclear Information System (INIS)

    Lappas, A.A.; Iatridis, D.; Vasalos, I.A.; Phyxogios, G.

    1999-01-01

    One of the more interesting ways for production of light olefins and for minimization of Gasoline olefins is the use of catalytic additives in the FCC (fluid catalytic cracking) inventory. The most widely used additive for the FCC process is the ZSM-5 which is a shape selective zeolite. When this additive is added to FCC units, it boosts the yields of LPG's olefins at the expense of gasoline, while increasing gasoline RON. The addition of ZSM-5 offers a great flexibility to a refinery since, in a relatively simple and cheap way, it can increase the RON and produces higher yields of light olefins. For all the above reasons the last years more studies are carried out in order to investigate the effect of this additive. In study presented in this paper, main emphasis was given, for the investigation of the effect of ZSM- 5 addition on FCC product distribution and especially on gasoline olefins. Moreover, in the previous literature works the ZSM-5 influences were examined using mainly fixed bed reactors. In the present study the investigation was carried out in a FCC pilot plant. The additive was also added in a commercial FCC unit of a Greek refinery (Hellenic Aspropyrgos Refinery - HAR) and thus comparison results of commercial and pilot plant test are also presented. The above study is part of a research collaboration which exists the last 10 years between the laboratory of Environmental Fuels and hydrocarbons of Chemical Process Engineering Research Institute (LEFH/CPERI) and the main Greek refineries (HEL.PETROLEUM, Motor Oil Hellas Refinery). The target of this research collaboration is i) the development of technology for the production of reformulated fuels and hydrocarbons and ii) to assist the Greek refineries to face the new regulations for environmental friendly fuels

  17. Direct NO decomposition over conventional and mesoporous Cu-ZSM-5 and Cu-ZSM-11 catalysts

    DEFF Research Database (Denmark)

    Kustova, Marina; Rasmussen, Søren Birk; Kustov, Arkadii

    2006-01-01

    Conventional Cu-ZSM-5 has for many years been recognized as a unique catalyst for direct NO decomposition. Zeolite-based catalysts have a crystallographically well-defined microporous structure. In such microporous catalysts, the creation and accessibility of the active sites is often influenced...... that ZSM-11 has only straight microporous channels, while ZSNI-5 has both straight and sinusoidal channels. Apparently, there is a preferential formation of active sites and/or improved accessibility in the straight channels compared to the sinusoidal channels, which make the ZSM-11 material a better...

  18. Zeolite-based SCR catalysts and their use in diesel engine emission treatment

    Science.gov (United States)

    Narula, Chaitanya K; Yang, Xiaofan

    2015-03-24

    A catalyst comprising a zeolite loaded with copper ions and at least one trivalent metal ion other than Al.sup.+3, wherein the catalyst decreases NO.sub.x emissions in diesel exhaust. The trivalent metal ions are selected from, for example, trivalent transition metal ions, trivalent main group metal ions, and/or trivalent lanthanide metal ions. In particular embodiments, the catalysts are selected from Cu--Fe-ZSM5, Cu--La-ZSM-5, Fe--Cu--La-ZSM5, Cu--Sc-ZSM-5, and Cu--In-ZSM5. The catalysts are placed on refractory support materials and incorporated into catalytic converters.

  19. Characterization of the Cu+ Sites in High-Silica Zeolites Interacting with CO Molecule: Combined Computational and Experimental Study

    Czech Academy of Sciences Publication Activity Database

    Davidová, Markéta; Nachtigallová, Dana; Bulánek, R.; Nachtigall, Petr

    2003-01-01

    Roč. 107, - (2003), s. 2327-2332 ISSN 1089-5647 R&D Projects: GA MŠk LN00A032; GA ČR GA203/00/0637 Institutional research plan: CEZ:AV0Z4040901 Keywords : exchanged ZSM-5 zeolite * x-ray absorption * photoluminescence spectra Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.679, year: 2003

  20. Performance Evaluations of Ion Exchanged Zeolite Membranes on Alumina Supports

    Energy Technology Data Exchange (ETDEWEB)

    Bhave, Ramesh R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jubin, Robert Thomas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Spencer, Barry B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nair, Sankar [Georgia Inst. of Technology, Atlanta, GA (United States)

    2017-08-27

    This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. In the first phase of this effort, several monovalent and divalent cation-exchanged silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on disk supports and characterized with gas and vapor permeation measurements. In the second phase, Linde Type A (LTA) zeolite membranes were synthesized in disk and tubular supports. The pervaporation process performance was evaluated for the separation and concentration of tritiated water.

  1. An operando optical fiber UV–vis spectroscopic study of the catalytic decomposition of NO and N2O over Cu-ZSM-5

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Groothaert, M.H.; Lievens, K.; Leeman, H.; Schoonheydt, R.A.

    2003-01-01

    The role of the bis(μ-oxo)dicopper core, i.e., [Cu2(μ-O)2]2+, in the decomposition of NO and N2O by the Cu-ZSM-5 zeolite has been studied with combined operando UV–vis monitoring of the catalyst and on-line GC analysis. An optical fiber was mounted on the outer surface of the quartz wall of the

  2. Conversion of methanol to hydrocarbons over conventional and mesoporous H-ZSM-5 and H-Ga-MFI: Major differences in deactivation behavior

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Højholt, Karen Thrane; Holm, Martin Spangsberg

    2012-01-01

    . In the methanol-to-hydrocarbons (MTH) process, H-ZSM-5 is subjected to coke formation leading to catalyst deactivation. Here we show that when the gallium containing zeotypes are employed in the MTH process, only insignificant amounts of coke are present in the deactivated catalysts, indicating distinct...... (hydrolysis) of the Ga&sbnd;O bonds in the zeolite structure rather than coke deposition....

  3. The investigation of order–disorder transition process of ZSM-5 induced by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Wang, Lianjun, E-mail: wanglj@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Jiang, Wan [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Lin, He, E-mail: linhe@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong, Shanghai 200120 (China)

    2014-04-01

    Based on the amorphization of zeolites, an order–disorder transition method was used to prepare silica glass via Spark Plasma Sintering (SPS). In order to get a better understanding about the mechanism of amorphization induced by SPS, the intermediate products in this process were prepared and characterized by different characterization techniques. X-ray diffraction and High-energy synchrotron X-ray scattering show a gradual transformation from ordered crystal to glass. Local structural changes in glass network including Si–O bond length, O–Si–O bond angle, size of rings, coordination were detected by Infrared spectroscopy and {sup 29}Si magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. Topologically ordered, amorphous material with a different intermediate-range structure can be obtained by precise control of intermediate process which can be expected to optimize and design material. - Graphical abstract: Low-density, ordered zeolites collapse to the rigid amorphous glass through spark plasma sintering. The intermediate-range structure formed in the process of order–disorder transition may give rise to specific property. - Highlights: • Order–disorder transition process of ZSM-5 induced by spark plasma sintering was investigated using several methods including XRD, High-energy synchrotron X-ray scattering, SAXS, IR, NMR, ect. • Order–disorder transition induced by SPS was compared with TIA and PIA. • Three stages has been divided during the whole process. • The collapse temperature range which may give rise to intermediate-range structure has been located.

  4. Aromatic hydrocarbon production via eucalyptus urophylla pyrolysis over several metal modified ZSM-5 catalysts – an analysis by py-GC/MS

    Science.gov (United States)

    Metal modified HZSM-5 catalysts were prepared by ion exchange of NH4ZSM-5 (SIO2/Al2O3 = 23) using gallium, molybdenum, nickel and zinc, and their combinations thereof. The prepared catalysts were used to evaluate catalytic pyrolysis for the conversion of Eucalyptus urophylla to fuels and chemicals, ...

  5. Chemical reactivity of cation-exchanged zeolites

    NARCIS (Netherlands)

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed

  6. Stability and activity of doped transition metal zeolites in the hydrothermal processing

    Directory of Open Access Journals (Sweden)

    Thomas François Robin

    2015-12-01

    Full Text Available This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper and iron in under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered as a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds which have an impact on the physical and chemical propriety of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts but their stability and activity under hydrothermal conditions is not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350 °C. Catalysts have been characterised before and after treatment using XRD, BET physisorption and STEM microscopy. Metal leaching was determined by analysis of the water phase following hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5 for example molybdenum improves the crystallinity of the zeolite. In general, metal doped zeolites were relatively stable under subcritical water. Activity of the catalysts for processing lipids, protein and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella and P. ellipsoidea. The catalysts exhibited greater activity towards converting lipids for example MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  7. Stability and Activity of Doped Transition Metal Zeolites in the Hydrothermal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Robin, Thomas François, E-mail: thomas.cognac@gmail.com; Ross, Andrew B.; Lea-Langton, Amanda R.; Jones, Jenny M. [School of Chemical and Process Engineering, University of Leeds, Leeds (United Kingdom)

    2015-12-14

    This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper, and iron under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion-exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds that have an impact on the physical and chemical properties of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts, but their stability and activity under hydrothermal conditions are not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350°C. Catalysts have been characterized before and after treatment using X-ray diffraction, BET physisorption, and scanning transmission electronic microscopy. Metal leaching was determined by the analysis of the water phase following the hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5, for example, molybdenum improves the crystallinity of the zeolite. In general, metal-doped zeolites were relatively stable in subcritical water. The activity of the catalysts for processing lipids, protein, and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella, and Pseudochoricystis ellipsoidea. The catalysts exhibited greater activity toward converting lipids, for example, MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  8. Stability and Activity of Doped Transition Metal Zeolites in the Hydrothermal Processing

    International Nuclear Information System (INIS)

    Robin, Thomas François; Ross, Andrew B.; Lea-Langton, Amanda R.; Jones, Jenny M.

    2015-01-01

    This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper, and iron under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion-exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds that have an impact on the physical and chemical properties of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts, but their stability and activity under hydrothermal conditions are not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350°C. Catalysts have been characterized before and after treatment using X-ray diffraction, BET physisorption, and scanning transmission electronic microscopy. Metal leaching was determined by the analysis of the water phase following the hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5, for example, molybdenum improves the crystallinity of the zeolite. In general, metal-doped zeolites were relatively stable in subcritical water. The activity of the catalysts for processing lipids, protein, and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella, and Pseudochoricystis ellipsoidea. The catalysts exhibited greater activity toward converting lipids, for example, MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  9. Ultrasound assisted dispersion of different amount of Ni over ZSM-5 used as nanostructured catalyst for hydrogen production via CO2 reforming of methane

    International Nuclear Information System (INIS)

    Vafaeian, Yaser; Haghighi, Mohammad; Aghamohammadi, Sogand

    2013-01-01

    Graphical abstract: A series of Ni/ZSM-5 nanocatalysts with different amount of Ni were prepared via ultrasound assisted method and characterized with XRD, FESEM, TEM, BET and FTIR techniques. The research deals with catalyst development for dry reforming of methane with the aim of reaching the most stable catalyst specifically over nano-sized catalysts. About more than 99% of Ni particles size is less than 100 nm for the sample prepared with 8% Ni, which is essential to the relative suppression of the carbon formation on catalysts. Catalyst prepared with 8% Ni content showed superior activity in process expected due to its better catalytic properties. - Highlights: • Using ZSM-5 zeolite in dry reforming of methane. • Employing ultrasound energy in synthesis of Ni/ZSM-5 nanocatalyst. • Enhancement of Ni particles size to meet desired catalyst at lower amount of Ni loading. • Dry reforming of methane over Ni/ZSM-5 nanocatalyst with different Ni-loading. • Superior activity of Ni/ZSM-5 nanocatalyst synthesized with 8% Ni content. - Abstract: Carbon dioxide reforming of methane is an interesting route for synthesis gas production especially over nanostructured catalysts. The present research deals with nanocatalyst development by sonochemical method for dry reforming of methane with the aim of reaching the most efficient nanocatalyst. Effect of Ni metal content, one of the most significant variables, on the properties of the ZSM-5 supported nanocatalysts was taken into account. The Ni/ZSM-5 nanocatalysts were prepared via assisted traditional impregnation method via ultrasound irradiation and characterized with XRD, FESEM, TEM, BET and FTIR techniques. Comparison of XRD patterns implies that the peaks related to NiO become sharper by increasing metal content over the support. In the case of nanocatalysts with lower metal content (3% and 8%), the beneficial influence of ultrasound assisted procedure become more pronounced and the observed reduction in

  10. Ion exchangers in radioactive waste management: natural Iranian zeolites.

    Science.gov (United States)

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

    2006-01-01

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

  11. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.

    2005-01-01

    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  12. ZEOLITE PERFORMANCE AS AN ANION EXCHANGER FOR ARSENIC SEQUESTRATION IN WATER

    Science.gov (United States)

    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...

  13. Influence of zeolite structure on the activity and durability of Co-Pd-zeolite catalysts in the reduction of NOx with methane

    International Nuclear Information System (INIS)

    Pieterse, J.A.Z.; Van den Brink, R.W.; Booneveld, S.; De Bruijn, F.A.

    2003-01-01

    Selective catalytic reduction of NO with CH 4 was studied over ZSM-5, MOR, FER and BEA zeolite-based cobalt (Co) and palladium (Pd) catalysts in the presence of oxygen and water. As compared to other catalytic systems reported in literature for CH 4 -SCR in the presence of water, zeolite supported Co-Pd combination catalysts are very active and selective. The most active catalysts, based on MOR and ZSM-5, are characterised by well-dispersed Pd ions in the zeolite that activate methane. Wet ion exchange is a good method to achieve high dispersion of Pd provided that it is carried out in a competitive manner. The presence of cobalt (Co 3 O 4 , Co-oxo ions) boosts SCR activity by oxidising NO to NO 2 . The activity of the zeolite-based Co-Pd combination catalysts decreases with prolonged times on stream. The severity of the deactivation was found to be different for different zeolite topologies. The characterisation and evaluation of freshly calcined catalysts and spent catalysts show two things that occur during reaction: (1) zeolite solvated metal cations disappear in favour of (inactive) metal oxides and presumably larger metal entities, i.e. loss of dispersion; (2) loss of crystallinity affiliated with steam-dealumination and the concomitant formation of extra-framework aluminium (EFAL) in the presence of water. Both phenomena strongly depend on the (reaction) temperature. The deactivation of Co-Pd-zeolite resembles the deactivation of Pd-zeolite. Hence, future research could encompass the stabilisation of Pd (cations) in the zeolite pores by exploring additives other than cobalt. For this, detailed understanding on the siting of Pd in zeolites is important

  14. Exchange, x-ray and IR spectral behaviour of lanthanum and praseodymium exchanged zeolite X

    International Nuclear Information System (INIS)

    Das, D.; Upreti, M.C.

    1995-01-01

    Exchange behaviour of lanthanum and praseodymium ions in zeolite X involves three steps: preferential exchange, intrazeolitic exchange and irreversible exchange. At room temperature , higher exchange has been observed with La(III) than with Pr(III) which is attributed to the smaller hydrosphere of lanthanum than praseodymium. IR spectra of these zeolites in KBr pellets show a shift in the major Si-O stretching vibration of 972 cm -1 to higher frequencies. Their x-ray diffraction patterns remain unchanged except a large decrease of the line intensities caused by the absorption of x-rays by heavy La(III) and Pr(III) ions. The present study reports the preparation and physicochemical properties of lanthanum and praseodymium exchanged zeolite X. (author). 12 refs., 3 figs., 3 tabs

  15. Progress on Zeolite-membrane-aided Organic Acid Esterification

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Dharmawijaya, P. T.

    2017-07-01

    Esterification is a common route to produce carboxylic acid esters as important intermediates in chemical and pharmaceutical industries. However, the reaction is equilibrium limited and needs to be driven forward by selective removal one of the products. There have been some efforts to selectively remove water from reaction mixture via several separation processes (such as pervaporation and reactive distillation). Integrated pervaporation and esterification has gained increasing attention towards. Inorganic zeolite is the most popular material for pervaporation due to its high chemical resistant and separation performance towards water. Zeolite also has proven to be an effective material in removing water from organic compound. Zeolite can act not only as selective layer but also simultaneously act as a catalyst on promoting the reaction. Hence, there are many configurations in integrating zeolite membrane for esterification reaction. As a selective layer to remove water from reaction mixture, high Si/Al zeolite is preferred to enhance its hydrophilicity. However, low Si/Al zeolite is unstable in acid condition due to dealumination thus eliminate its advantages. As a catalyst, acid zeolites (e.g. H-ZSM-5) provide protons for autoprotolysis of the carboxylic acid similar to other catalyst for esterification (e.g. inorganic acid, and ion exchange resins). There are many studies related to zeolite membrane aided esterification. This paper will give brief information related to zeolite membrane role in esterification and also research trend towards it.

  16. Hollow ZSM-5 encapsulated Pt nanoparticles for selective catalytic reduction of NO by hydrogen

    Science.gov (United States)

    Hong, Zhe; Wang, Zhong; Chen, Dan; Sun, Qiang; Li, Xuebing

    2018-05-01

    Pt nanoparticles were successfully encapsulated in hollow ZSM-5 single crystals by tetrapropylammonium hydroxide (TPAOH) hydrothermal treatment with an "dissolution-recrystallization" process. The prepared Pt/hollow ZSM-5 (Pt/h-ZSM-5re) sample exhibited the best activity and a maximum NO conversion of 84% can be achieved at 90 °C with N2 selectivity of 92% (GHSV = 50,000 h-1). Meanwhile, Pt/h-ZSM-5re catalyst exhibited excellent SO2, H2O resistance and durability, which was related to the stabilization of Pt active sites by hollow structure during H2-SCR. It was found that the increase of NO2 concentration in the feed gas mixture led to an activity decline. In addition, the H2-SCR reaction routes over Pt/hollow ZSM-5 catalyst at different temperature were investigated.

  17. Ion-exchange properties of cesium and strontium into zeolites from sodium salt solutions

    International Nuclear Information System (INIS)

    Kanno, Takuji; Hashimoto, Hiroyuki; Ohtani, Tozo.

    1978-01-01

    The ion-exchange properties of cesium and strontium into zeolite from sodium salt solution has been studied in zeolite A, zeolite X, zeolite Y, mordenite and clinoptilolite. The distribution of cesium into mordenite from about 1 -- 2 M sodium chloride and sodium hydroxide solutions is considerably larger than that into zeolite A. The distribution coefficient for 2 M solution of sodium salts was about 300. Therefore, the separation of cesium from sodium salt solution is possible by using mordenite. The distribution of strontium into zeolites form 1 -- 2 M solutions of sodium chloride and sodium nitrate were in the order of zeolite A>zeolite X>zeolite Y asymptoticaly equals mordenite. The distribution coefficient of 230 was obtained for 1 M solutions of sodium salts. The anion in solutions had no effect on the distribution of cesium and strontium into zeolite from sodium salt solution. (author)

  18. Organic iodide capture using a zeolite dry filtration

    International Nuclear Information System (INIS)

    Park, Sanggil; Sung, Joonyoung; Kim, Gi-ppeum; Lee, Jaeyoung

    2017-01-01

    An organic iodide, especially, methyl iodide (CH 3 I) would generated non-negligibly from a severe accident in a nuclear power plant. This CH 3 I will be dangerous for human when it was inhaled, it is highly toxic and causes a serious nerve disorder. Even it is a major contributor to a thyroid cancer. In order to prevent its environmental release, it is required to decontaminate using a filtration system. For the removal of CH 3 I from the release gases, wet-type is not ideal due to a high re-volatile characteristics of CH 3 I. It may become volatile after dissolving in a pool and forms CH 3 I again at the surface of water pool. Therefore, a dry-filtration should be installed to remove the CH 3 I. In this study, we preliminary investigate the characteristics of zeolite filtration methods for the removal of CH 3 I. We used both silver ion exchanged ZSM-5-zeolite (Ag+-ZSM-5) to study the effect of silver ion for the removal of iodine from CH 3 I. In summary, the CH 3 I capture tests using a silver ion exchanged zeolite was conducted in the coupled TGAGC test set-up. The mass change of the sample and concentration of CH 3 I were measured. The samples were investigated by the SEM/EDS to see its surface characteristics.

  19. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  20. The potential of medium-pore zeolites for improved propene yields from catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Bager, F.; Salas, N.; Ernst, S. [Technische Univ. Kaiserslautern (Germany). Dept. of Chemistry, Chemical Technology

    2011-07-01

    The medium-pore zeolites ZSM-5 (MFI), ZSM-22 (TON), ZSM-23 (MTT), and EU-1 (EUO) were synthesized under hydrothermal conditions and modified by ion exchange to obtain the Broensted-acid forms. The activity and selectivity of these catalysts in catalytic cracking of a model compound, viz. n-octane, was studied in a fixed-bed flow-type reactor. The catalytic results clearly reflect the differences in the pore architectures of the tested zeolites on n-octane conversion and on the product selectivities. Over the zeolites with one-dimensional pore systems and without large intracrystalline cavities, a remarkable increase of the contribution of the monomolecular cracking mechanism could be observed as compared to the standard catalyst zeolite ZSM-5. This is indicated by a high selectivity for unsaturated products and, hence, increasing yields of propene. Large cavities in the pore system, viz. in the case of zeolite EU-1, increase the conversion in particular at lower temperatures. However, the large cavities also favor the formation of large transition states required for the classical bimolecular cracking mechanism, resulting in decreased selectivities for unsaturated products, increased selectivities for aromatics formation and faster deactivation. (orig.)

  1. Synthesis of novel perfluoroalkylglucosides on zeolite and non-zeolite catalysts.

    Science.gov (United States)

    Nowicki, Janusz; Mokrzycki, Łukasz; Sulikowski, Bogdan

    2015-04-08

    Perfluoroalkylglucosides comprise a very important class of fluorine-containing surfactants. These compounds can be synthesized by using the Fisher reaction, starting directly from glucose and the required perfluoroalcohols. We wish to report on the use of zeolite catalysts of different structure and composition for the synthesis of perfluoroalkylglucosides when using glucose and 1-octafluoropentanol as substrates. Zeolites of different pore architecture have been chosen (ZSM-5, ZSM-12, MCM-22 and Beta). Zeolites were characterized by XRD, nitrogen sorption, scanning electron microscopy (SEM) and solid-state 27Al MAS NMR spectroscopy. The activity of the zeolite catalysts in the glycosidation reaction was studied in a batch reactor at 100 °C below atmospheric pressure. The performance of zeolites was compared to other catalysts, an ion-exchange resin (Purolite) and a montmorillonite-type layered aluminosilicate. The catalytic performance of zeolite Beta was the highest among the zeolites studied and the results were comparable to those obtained over Purolite and montmorillonite type catalysts.

  2. Effect of Annealing Temperature on Broad Luminescence of Silver-Exchanged Zeolites Y and A

    Science.gov (United States)

    Gui, Sa Chu Rong; Lin, H.; Bao, W.; Wang, W.

    2018-05-01

    The annealing temperature dependence of luminescence properties of silver (Ag)-exchanged zeolites Y and A was studied. It was found that the absorbance and excitation/emission bands are strongly affected by the thermal treatments. With increase in annealing temperature, the absorbance of Ag in zeolite Y increases at first and then decreases. However, the position of the excitation/emission band in zeolite Y was found to be insensitive to the annealing temperature. In contrast, the excitation/emission bands in zeolite A are particularly sensitive to the annealing temperature. The difference of such temperature dependence in zeolites Y and A may be due to the different microporous structure of the two minerals. Moreover, the fact that this dependence is not observed in Ag-exchanged zeolite Y is likely to be due to the difficulty in dehydration of zeolite Y in air or due to the weak Ag+-Ag+ interaction in zeolite Y.

  3. Assessing the acid properties of desilicated ZSM-5 by FTIR using CO and 2,4,6-trimethylpyridine (collidine) as molecular probes

    DEFF Research Database (Denmark)

    Holm, Martin Spangsberg; Svelle, S.; Joensen, F.

    2009-01-01

    Lewis acid sites were generated, presumably from dislodged framework aluminium. Collidine, which is too bulky to enter the micropore system of ZSM-5, could access Lewis acidity, suggesting that these sites were predominantly generated on the external surface or in the newly created mesopores....... Additionally, by first saturating the zeolite surface with collidine and subsequently adsorbing CO, we show that barely any Lewis acidity was uncoordinated post-collidine saturation while the Bronsted acidity continuously was protected behind the micropore system. It is hypothesized from the present study...

  4. Tailoring of the structure of Fe-cationic species in Fe-ZSM-5 by distribution of Al atoms in the framework for N2O decomposition and NH3-SCR-NOx

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Wichterlová, Blanka; Tabor, Edyta; Šťastný, Petr; Sathu, Naveen Kumar; Sobalík, Zdeněk; Dědeček, Jiří; Sklenák, Štěpán; Klein, Petr; Vondrová, Alena

    2014-01-01

    Roč. 312, APR 2014 (2014), s. 123-138 ISSN 0021-9517 R&D Projects: GA ČR GAP106/11/0624; GA TA ČR TA01021377 Institutional support: RVO:61388955 Keywords : Fe-ZSM-5 zeolite * Structure of Fe species * Fe(III)-oxo species Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.921, year: 2014

  5. Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

    Science.gov (United States)

    Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

    2014-03-01

    Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Selective adsorption of thiophene and 1-benzothiophene on metal-ion-exchanged zeolites in organic medium.

    Science.gov (United States)

    Xue, Mei; Chitrakar, Ramesh; Sakane, Kohji; Hirotsu, Takahiro; Ooi, Kenta; Yoshimura, Yuji; Feng, Qi; Sumida, Naoto

    2005-05-15

    Adsorption of the organic sulfur compounds thiophene (TP) and 1-benzothiophene (1-BTP) in an organic model solution of hydrodesulfurizated gasoline (heptane with 1 wt% toluene and 0.156 mM (5 ppmw as sulfur) TP or 1-BTP) was studied by a batch method at 80 degrees C using metal-ion-exchanged Y-zeolites. Although NaY-zeolite or its acid-treated material rarely adsorbed the organic sulfur compounds, NaY-zeolites exchanged with Ag+, Cu2+, and Ce3+ ions and NH(4)Y-zeolites exchanged with Ce3+ ions showed markedly high adsorptive capacities for TP and 1-BTP. The sulfur uptake increased in the order CuY-zeolite(Na)(Na) for both the organic sulfur compounds. The adsorption isotherms for TP and 1-BTP followed the Langmuir's relationship and the saturation capacities by CeY-zeolite(Na) were calculated as 0.022 and 0.033 mmol/g, respectively. The mole ratios of TP/Ce and 1-BTP/Ce were 0.031 and 0.047, respectively. CeY-zeolite(NH4) which was prepared from NH4Y-zeolite showed less uptake of TP and 1-BTP than CeY-zeolite(Na), probably due to its lower cerium content.

  7. Design of zeolite ion-exchange columns for wastewater treatment

    International Nuclear Information System (INIS)

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

    1991-01-01

    Oak Ridge National Laboratory plans to use chabazite zeolites for decontamination of wastewater containing parts-per-billion levels of 90 Sr and 137 Cs. Treatability studies indicate that such zeolites can remove trace amounts of 90 Sr and 137 Cs from wastewater containing high concentrations of calcium and magnesium. These studies who that zeolite system efficiency is dependent on column design and operating conditions. Previous results with bench-scale, pilot-scale, and near-full-scale columns indicate that optimized design of full-scale columns could reduce the volume of spent solids generation by one-half. The data indicate that shortcut scale-up methods cannot be used to design columns to minimize secondary waste generation. Since the secondary waste generation rate is a primary influence on process cost effectiveness, a predictive mathematical model for column design is being developed. Equilibrium models and mass-transfer mechanisms are being experimentally determined for isothermal multicomponent ion exchange (Ca, Mg, Na, Cs, and Sr). Mathematical models of these data to determine the breakthrough curves for different column configurations and operating conditions will be used to optimize the final design of full-scale treatment plant. 32 refs., 6 figs., 3 tabs

  8. Theoretical evidence of the observed kinetic order dependence on temperature during the N(2)O decomposition over Fe-ZSM-5.

    Science.gov (United States)

    Guesmi, Hazar; Berthomieu, Dorothee; Bromley, Bryan; Coq, Bernard; Kiwi-Minsker, Lioubov

    2010-03-28

    The characterization of Fe/ZSM5 zeolite materials, the nature of Fe-sites active in N(2)O direct decomposition, as well as the rate limiting step are still a matter of debate. The mechanism of N(2)O decomposition on the binuclear oxo-hydroxo bridged extraframework iron core site [Fe(II)(mu-O)(mu-OH)Fe(II)](+) inside the ZSM-5 zeolite has been studied by combining theoretical and experimental approaches. The overall calculated path of N(2)O decomposition involves the oxidation of binuclear Fe(II) core sites by N(2)O (atomic alpha-oxygen formation) and the recombination of two surface alpha-oxygen atoms leading to the formation of molecular oxygen. Rate parameters computed using standard statistical mechanics and transition state theory reveal that elementary catalytic steps involved into N(2)O decomposition are strongly dependent on the temperature. This theoretical result was compared to the experimentally observed steady state kinetics of the N(2)O decomposition and temperature-programmed desorption (TPD) experiments. A switch of the reaction order with respect to N(2)O pressure from zero to one occurs at around 800 K suggesting a change of the rate determining step from the alpha-oxygen recombination to alpha-oxygen formation. The TPD results on the molecular oxygen desorption confirmed the mechanism proposed.

  9. Measurement of cation exchange capacity (CEC) on natural zeolite by percolation method

    Science.gov (United States)

    Wiyantoko, Bayu; Rahmah, Nafisa

    2017-12-01

    The cation exchange capacity (CEC)measurement has been carried out in natural zeolite by percolation method. The natural zeolite samples used for cation exchange capacity measurement were activated beforehand with physical activation and chemical activation. The physically activated zeolite was done by calcination process at 600 °C for 4 hours. The natural zeolite was activated chemically by using sodium hydroxide by refluxing process at 60-80 °C for 3 hours. In summary, cation exchange capacity (CEC) determination was performed by percolation, distillation and titration processes. Based on the measurement that has been done, the exchange rate results from physical activated and chemical activated of natural zeolite were 181.90cmol (+)/kg and 901.49cmol (+)/kg respectively.

  10. Temperature-Induced Desorption of Methyl tert-Butyl Ether Confined on ZSM-5: An In Situ Synchrotron XRD Powder Diffraction Study

    Directory of Open Access Journals (Sweden)

    Elisa Rodeghero

    2017-02-01

    Full Text Available The temperature-induced desorption of methyl tert-butyl ether (MTBE from aqueous solutions onto hydrophobic ZSM-5 was studied by in situ synchrotron powder diffraction and chromatographic techniques. This kind of information is crucial for designing and optimizing the regeneration treatment of such zeolite. The evolution of the structural features monitored by full profile Rietveld refinements revealed that a monoclinic (P21/n to orthorhombic (Pnma phase transition occurred at about 100 °C. The MTBE desorption process caused a remarkable change in the unit-cell parameters. Complete MTBE desorption was achieved upon heating at about 250 °C. Rietveld analysis demonstrated that the desorption process occurred without any significant zeolite crystallinity loss, but with slight deformations in the channel apertures.

  11. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

    Directory of Open Access Journals (Sweden)

    Debarpita Ghosal

    2015-07-01

    Full Text Available The performance of toluene methylation reaction was studied on H-ZSM-5 catalyst modified with La, Ce and Nb at different percentage loading. It was found that 10% metal loading produced the best performance in the reaction in terms of toluene conversion. The catalyst was coated on silicon carbide foam support which showed better conversion than the pelleted catalyst. Again, among the treated and untreated H-ZSM-5, the La-ZSM-5 catalyst is chosen for the reaction for its highest selectivity towards xylene, the main product. All catalysts were characterized in terms of surface properties, SEM, XRD and NH3-TPD. Kinetic study was done on La-ZSM-5 catalyst with 10% loading. In this kineticstudy, Langmuir Hinshelwood kinetic model with surface reaction as rate controlling step was selected as the rate equation. The activation energy was found to be 47 kJ/mol. © 2015 BCREC UNDIP. All rights reserved. Received: 9th December 2014; Revised: 27th April 2015; Accepted: 29th April 2015  How to Cite: Ghosal, D., Basu, J.K., Sengupta, S. (2015. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 201-209. (doi:10.9767/bcrec.10.2.7872.201-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7872.201-209  

  12. Occluded cobalt species over ZSM-5 matrix: Design, preparation, characterization and magnetic behavior

    International Nuclear Information System (INIS)

    Pierella, Liliana B.; Saux, Clara; Bertorello, Hector R.; Bercoff, Paula G.; Botta, Pablo M.; Rivas, J.

    2008-01-01

    Co-containing molecular sieves with MFI structure was synthesized by the hydrothermal crystallization method and cobalt was incorporated in it by wet impregnation at different percentages. Thermal post-treatments were applied to Co-ZSM-5: calcination and reduction. X ray diffraction (XRD) and FTIR studies confirmed crystallinity, structure and orthorhombic symmetry of the obtained samples (Co-ZSM-5 calcined and Co-ZSM-5 reduced). The XRD, Raman spectroscopy, SEM and TPR techniques for the calcined samples showed the presence of Co 3 O 4 which diminished in the reduced samples and Co 0 appeared. The magnetic behavior of the materials was evaluated by magnetization (M) variation with applied magnetic field (H) at different temperatures. Low magnetization is observed in the calcined samples while high values are attained in the reduced samples, due to the presence of metallic Co

  13. Ion-exchange properties of zeolite/glass hybrid materials

    International Nuclear Information System (INIS)

    Taira, Nobuyuki; Yoshida, Kohei; Fukushima, Takuya

    2017-01-01

    Hybrid materials were prepared from ground glass powder and various zeolites such as A-type, mordenite, X-type, and Y-type zeolites, and their ion removal effect was investigated. The hybrid materials of A-type, Y-type, and mordenite zeolites showed similar Sr"2"+ removal rates from aqueous solutions. The removal rate of Sr"2"+ ions increased as the amount of zeolite in the hybrid materials increased. Compared with other hybrid materials, the hybrid materials of X-type zeolite showed higher Sr"2"+ removal rates, especially for zeolite content greater than 25%. As the amount of X-type zeolite in the hybrid materials increased, the Sr"2"+ removal rate increased greatly, with a 100% removal rate when the content of X-type zeolite exceeded 62.5%. (author)

  14. Catalytic reduction of nitric oxide with ammonia over transition metal ion-exchanged Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Sciyama, T; Arakawa, T; Matsuda, T; Yamazoe, N; Takita, Y

    1975-01-01

    The catalytic reduction of nitric oxide with ammonia was studied over transition metal ion-exchanged Y zeolite (Me-Y) catalysts. The reaction products are nitrogen, nitrous oxide, and water in all cases. Selectivities to N/sub 2/ are 60 to 80% on all the cation exchanged zeolite catalysts exhibiting a relatively minor variation with the cationic species exchanged. The copper (II)-Y catalyst exhibits low temperature activity and has an unusual catalytic activity-temperature profile with a maximum at 120/sup 0/C. The catalytic activity is enhanced considerably when a second cation, especially cobalt (II) or iron (III) is coexchanged together with Cu (II) in Y zeolite.

  15. Electrospun Zeolite/Cellulose Acetate Fibers for Ion Exchange of Pb2+

    Directory of Open Access Journals (Sweden)

    Daniel N. Tran

    2014-12-01

    Full Text Available The ion exchange capability of electrospun cellulose acetate (CA fibers containing zeolite A nanoparticles is reported. Solid and porous CA fibers were used to make a zeolite-embedded filter paper, which was then used to ion exchange Na+ with Cu2+ and Pb2+. The composite Linde Type A (LTA zeolite CA fibers exchanged 0.39 mmol/g more Pb2+ than LTA nanoparticles in the solid CA fibers. These fibers could provide a simple and effective method for heavy metal ion removal in water.

  16. Evidence for F-/SiO- anion exchange in the framework of As-synthesized all-silica zeolites

    KAUST Repository

    Liu, Xiaolong; Ravon, Ugo; Tuel, Alain

    2011-01-01

    Not everything changes: Charge-compensating anions can be exchanged in as-synthesized zeolite frameworks with changes in both the density of defect sites and of the hydrophobic character of the zeolite. The reversible transformation occurs without

  17. Environmental applications of natural zeolitic materials based on their ion-exchange properties

    International Nuclear Information System (INIS)

    Colella, C.

    1998-01-01

    Natural zeolites, such as clinoptilolite, chabazite, phillipsite and mordenite, exhibit good selectivities for some water pollutants, e.g., Cs + , NH 4 + and Pb 2+ . Zeolite-rich tuffs may be therefore utilized for removing the above and other cations from wastewaters before discharge. Continuous processes with fixed beds are usually employed for water purification, such as those in service in the U.S.A for ammonium removal from municipal sewage. Direct action of the ion exchanger is needed when the pollutant must be removed from soil and trapped in the zeolite framework. Discontinuous processes (addition of zeolite to the waste solution) are also possible, provided the polluted zeolitic sludge is stabilized-solidified in a cement matrix matrix before disposal. Removal of radionuclides from nuclear power plant waters with natural zeolites is discussed

  18. Desorption of acetone from alkaline-earth exchanged Y zeolite after propane selective oxidation

    NARCIS (Netherlands)

    Xu, J.; Mojet, Barbara; van Ommen, J.G.; Lefferts, Leonardus

    2004-01-01

    The desorption of products from a series of alkaline-earth exchanged Y zeolites after room-temperature propane selective oxidation was investigated by in situ infrared and mass spectroscopy. The intermediate product, isopropylhydroperoxide (IHP), did not desorb during

  19. Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts

    NARCIS (Netherlands)

    Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.

    2016-01-01

    Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved

  20. Direct synthesis of carbon-templating mesoporous ZSM-5 using microwave heating

    Czech Academy of Sciences Publication Activity Database

    Koo, J.-B.; Jiang, N.; Saravanamurugan, S.; Voláková, Martina; Musilová, Zuzana; Čejka, Jiří; Park, S.-E.

    2010-01-01

    Roč. 276, č. 2 (2010), s. 327-334 ISSN 0021-9517 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous ZSM-5 * template * microwave irradiation * carbon Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.415, year: 2010

  1. The conversion of dimethyl ether over Pt/H-ZSM5. A bifunctional catalyzed reaction

    NARCIS (Netherlands)

    Engelen, C.W.R.; Wolthuizen, J.P.; Hooff, van J.H.C.; Imelik, B.; Naccache, C.; Coudurier, G.

    1985-01-01

    At low temperatures dimethylether mixed with hydrogen reacts over a platinum loaded H-ZSM5 catalyst selectivity to methane. Two successive steps can be distinguished; first the acid-catalyzed formation of a trimethyloxoniumion, followed by a metal-catalyzed hydrogenation to methane. Experiments with

  2. DFT calculations on N2O decomposition by binuclear Fe complexes in Fe/ZSM-5

    NARCIS (Netherlands)

    Yakovlev, A.L.; Zhidomirov, G.M.; Santen, van R.A.

    2001-01-01

    N2O decomposition catalyzed by oxidized Fe clusters localized in the micropores of Fe/ZSM-5 has been studied using the DFT approach and a binuclear cluster model of the active site. Three different reaction routes were found, depending on temperature and water pressure. The results show that below

  3. Synthesis of ZSM-5 on the Surface of Foam Type Porous SiC Support

    International Nuclear Information System (INIS)

    Jung, Eunjin; Lee, Yoon Joo; Won, Ji Yeon; Kim, Younghee; Kim, Soo Ryong; Shin, Dong-Geun; Kwon, Woo Teck; Lee, Hyun Jae

    2015-01-01

    ZSM-5 crystals grew by hydrothermal synthesis method on the surface of foam type porous silicon carbide ceramics which fabricated by polymer replica method. Oxide layer was developed on the surface of the porous silicon carbide ceramics to induce growth of ZSM-5 from the surface. In this study, hydrothermal synthesis was carried out for 7 h at 150 .deg. C using TEOS, Al(NO 3 )•9H 2 O and TPAOH as raw materials in the presence of the porous silicon carbide ceramics. X-ray Powder Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were confirmed 1-3 μm sized ZSM-5 crystals have grown on the surface of porous silicon carbide ceramics. BET data shows that small pores about 10Å size drastically enhanced and surface area increased from 0.83 m 2 /g to 30.75 m 2 /g after ZSM-5 synthesis on the surface of foam type porous silicon carbide ceramics.

  4. Oxygen exchange between C18O2 and ''acidic'' oxide and zeolite catalysts

    International Nuclear Information System (INIS)

    Peri, J.B.

    1975-01-01

    The exchange of oxygen between C 18 O 2 and several high-area oxides, including silica, γ-alumina, silica--alumina, and zeolite catalysts, was studied. Infrared spectra of adsorbed CO 2 and of surface ''carbonates'' were used to follow the rate of oxygen exchange and investigate the nature of unusually exchangeable surface oxide ions, present at low concentrations. Interaction of CO 2 with the surface typically produced initial exchange of one oxygen atom, as expected from interaction with a single oxide ion (CO 2 + O 2- reversible CO 3 2- ), and the number of exchangeable ions increased with increasing temperature. The rate of oxygen exchange did not correlate with chemisorption to form stable surface carbonates or with the extent of strong physical adsorption of CO 2 . With dry silica, exchange was insignificant below 600 0 ; with catalytically active zeolites and dry γ-alumina, it was detectable at 200 0 and fairly rapid at 300--400 0 . Silica--alumina required 100--150 0 higher temperature for exchange than did an active zeolite. Activity for cracking and other hydrocarbon reactions may be related to the ease of exchange of some surface oxide ions with CO 2 . Active zeolites have reactive oxide sites resembling those on dry γ-alumina, but such sites on zeolites are probably less-readily eliminated by chemisorption of H 2 O or other compounds. (U.S.)

  5. Livestock wastewater treatment by zeolite ion exchange and gamma-ray irradiation

    International Nuclear Information System (INIS)

    Lee, Sang Ryul; Kim, Tak Hyun; Lee, Myun Joo

    2008-01-01

    Livestock wastewater containing high concentrations of organic matters and ammonia-nitrogen has been known as one of the recalcitrant wastewater. It is difficult to treat by conventional wastewater treatment techniques. This study was carried out to evaluate the feasibility of zeolite ion exchange and gamma-ray irradiation treatment of livestock wastewater. The removal efficiencies of SCOD Cr and NH3-N were significantly enhanced by gamma-ray irradiation after zeolite ion exchange as a pre-treatment. However, the effects of zeolite particle size on the SCOD Cr and NH 3 -N removal efficiencies were insignificant. These results indicate that the combined process of zeolite ion exchange and gamma-ray irradiation has potential for the treatment of livestock wastewater

  6. Zeolite and wollastonite synthesis from rice hull ash

    International Nuclear Information System (INIS)

    Fernandes, Alberto de Andrade

    2006-01-01

    Rice hull ash (RHA) is a industry scrap rich in amorphous silica. A simple and low-energy cost method for the extraction of this silica was researched. A low level of impurity and high reactivity material was produced, which is appropriate for the synthesis of zeolites and wollastonite (CaSiO 3 ). The synthetic zeolites has not similar structures in nature, and they have been more and more valued in the market due to their purity and efficiency in specific applications like ion exchange, molecular sieve and catalysis areas. High purity wollastonite has many applications in manufacturing and agriculture. The mineral wollastonite can be formed in nature in different ways; it is generally accepted two forming processes, both encompassing limestone metamorphism (heat and pressure). In this work, a new process for the synthesis of zeolites and wollastonite from RHA colloidal silica was developed. Moreover, the process is aimed at lower energy costs, fewer stages and fewer reactants consume. In this work, zeolite A used in detergent and zeolite ZSM-5, employed in the petrochemical industry due to its high selectivity in catalytic reactions and its high thermo and acid stability, were synthesized. The first step of the wollastonite synthesis was studied, with the purpose of obtaining calcium hydrosilicate. Eleven different hydrosilicates occur in the system Ca(OH) 2 -SiO 2 -H 2 O, in the second step it was annealed to form the wollastonite phase. (author)

  7. Thermal change and ion exchange properties of zeolite L with cesium and strontium

    International Nuclear Information System (INIS)

    Mimura, Hitoshi; Akiba, Kenichi

    1986-01-01

    Thermal change and ion exchange properties of Cs and Sr have been studied for zeolite L. The zeolite structure is stable below 900 deg C and converts to the amorphous phase above 1000 deg C. The cesium form of zeolite L recrystallized to pollucite (CsAlSi 2 O 6 ) by calcination at 1400 deg C for 1 h or under hydrothermal condition (300 deg C, 290 atm, 24 h). Hydrogen-form zeolites were prepared by the acid treatment in 10 -2 ∼ 10 -1 M HNO 3 solutions or thermal decomposition of NH 4 form zeolites at 460 ∼ 500 deg C. The distribution of Cs and Sr was dependent on equilibrium pH and the distribution coefficient (K d ) was about 10 4 (ml/g) at pH 5 ∼ 7. The exchange capacity of Cs and Sr was 0.89 (meq./g zeolite) and exchanging ratio was 68 % at D sites in main channel. These cations in zeolite were completely eluted with 10 -1 M HNO 3 solution. (author)

  8. New ion-exchanged zeolite derivatives: antifungal and antimycotoxin properties against Aspergillus flavus and aflatoxin B1

    Science.gov (United States)

    Savi, Geovana D.; Cardoso, Willian A.; Furtado, Bianca G.; Bortolotto, Tiago; Da Agostin, Luciana O. V.; Nones, Janaína; Torres Zanoni, Elton; Montedo, Oscar R. K.; Angioletto, Elidio

    2017-08-01

    Zeolites are microporous crystalline hydrated aluminosilicates with absorbent and catalytic properties. This material can be used in many applications in stored-pest management such as: pesticide and fertilizer carriers, animal feed additives, mycotoxin binders and food packaging materials. Herein, four 4A zeolite forms were prepared by ion-exchange and their antifungal effect against Aspergillus flavus was highlighted. Additionally, the antimycotoxin activity and the aflatoxin B1 (AFB1) adsorption capacity of these zeolites as well as their toxic effects on Artemia sp. were investigated. The ion-exchanged zeolites with Li+ and Cu2+ showed the best antifungal activity against A. flavus, including effects on conidia germination and hyphae morphological alterations. Regarding to antimycotoxin activity, all zeolite samples efficiently inhibited the AFB1 production by A. flavus. However, the ion-exchanged zeolites exhibited better results than the 4A zeolite. On the other hand, the AFB1 adsorption capacity was only observed by the 4A zeolite and zeolite-Li+. Lastly, our data showed that all zeolites samples used at effective concentrations for antifungal and antimycotoxin assays (2 mg ml-1) showed no toxic effects towards Artemia sp. Results suggest that some these ion-exchanged zeolites have great potential as an effective fungicide and antimycotoxin agent for agricultural and food safety applications.

  9. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my; Ibrahim, Zaharah

    2016-01-01

    Graphical abstract: - Highlights: • Functionalization of Ag-exchanged zeolite NaY with 3-aminopropyltriethoxysilane APTES (ZSA) as antibacterial agent. • Antibacterial assay of ZSA was performed against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538. • Functionalization of Ag-exchanged zeolite NaY with APTES significantly increased the antibacterial agent. • Different mechanisms of bacterial death were suggested for each bacteria type by the functionalized Ag-exchanged zeolite NaY. - Abstract: Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver

  10. Influence of oxalate ligand functionalization on Co/ZSM-5 activity in Fischer Tropsch synthesis and hydrodeoxygenation of oleic acid into hydrocarbon fuels.

    Science.gov (United States)

    Ayodele, Olumide Bolarinwa

    2017-08-30

    Achieving high degree of active metal dispersions at the highest possible metal loading and high reducibility of the metal remains a challenge in Fischer Tropsch synthesis (FTS) as well as in hydrogeoxygenation (HDO).This study therefore reports the influence of oxalic acid (OxA) functionalization on the metal dispersion, reducibility and activity of Co supported ZSM-5 catalyst in FTS and HDO of oleic acid into paraffin biofuel. The Brunauer-Emmett-Teller (BET) results showed that cobalt oxalate supported ZSM-5 catalyst (CoOx/ZSM-5) synthesized from the incorporation of freshly prepared cobalt oxalate complex into ZSM-5 displayed increase in surface area, pore volume and average pore size while the nonfunctionalized cobalt supported on ZSM-5 (Co/ZSM-5) catalyst showed reduction in those properties. Furthermore, both XRD and XPS confirmed the presence of Co° formed from the decomposition of CoOx during calcination of CoOx/ZSM-5 under inert atmosphere. The HRTEM showed that Co species average particle sizes were smaller in CoOx/ZSM-5 than in Co/ZSM-5, and in addition, CoOx/ZSM-5 shows a clear higher degree of active metal dispersion. The FTS result showed that at CO conversion over Co/ZSM-5 and CoOx/ZSM-5 catalysts were 74.28% and 94.23% and their selectivity to C 5+ HC production were 63.15% and 75.4%, respectively at 4 h TOS. The HDO result also showed that the CoOx/ZSM-5 has higher OA conversion of 92% compared to 59% over Co/ZSM-5. In addition CoOx/ZSM-5 showed higher HDO and isomerization activities compared to Co/ZSM-5.

  11. Characterization Of Cobalt-Exchanged Zeolite A By DRIFT Spectroscopy

    Science.gov (United States)

    Kappers, M. J.; van der Maas, John H.; Chalmers, J. M.; Howard, J.

    1989-12-01

    In-situ DRIFT spectroscopy has been succesfully used for the characterization of Co4Na4-A. Dehydration of the zeolite A appears to involve formation and breakdown of hydration complexes and hydrolysis. The position of cations and hydroxyl groups within the zeolite structure was derived from the adsorption of carbon monoxide and acetonitrile.

  12. Selective catalytic reduction of nitric oxide by ammonia over Cu-exchanged Cuban natural zeolites

    International Nuclear Information System (INIS)

    Moreno-Tost, Ramon; Santamaria-Gonzalez, Jose; Rodriguez-Castellon, Enrique; Jimenez-Lopez, Antonio; Autie, Miguel A.; Glacial, Marisol Carreras; Gonzalez, Edel; Pozas, Carlos De las

    2004-01-01

    The catalytic selective reduction of NO over Cu-exchanged natural zeolites (mordenite (MP) and clinoptilolite (HC)) from Cuba using NH 3 as reducing agent and in the presence of excess oxygen was studied. Cu(II)-exchanged zeolites are very active catalysts, with conversions of NO of 95%, a high selectivity to N 2 at low temperatures, and exhibiting good water tolerance. The chemical state of the Cu(II) in exchanged zeolites was characterized by H 2 -TPR and XPS. Cu(II)-exchanged clinoptilolite underwent a severe deactivation in the presence of SO 2 . However, Cu(II)-exchanged mordenite not only maintained its catalytic activity, but even showed a slight improvement after 20h of reaction in the presence of 100ppm of SO 2

  13. Investigatons on the local structure of AG+/ZSM-5 catalysts and their photocatalytic reactivities for the decomposition of N2O at 298 κ

    International Nuclear Information System (INIS)

    Matsuoka, Masaya; Ju, Woo-Sung; Yamashita, Hiromi; Anpo, Masakazu

    2001-01-01

    Ag + /ZSM-5 catalysts were prepared by an ion-exchange method and UV-irradiation of the catalysts in the presence of N 2 O led to the photo-catalytic decomposition of N 2 O into N 2 and O 2 at 298 κ. Investigations on the effective wavelength of irradiated UV-light for the reaction as well as the in-situ characterization of the catalysts by means of XAFS, UV-Vis, photoluminescence and FT-IR spectroscopies revealed that the photoexcitation of the Ag + -N 2 O complexes formed between gaseous N 2 O and the isolated Ag + ions play a significant role in this reaction. (au)

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

    Science.gov (United States)

    Hui, K S; Chao, C Y H

    2008-10-01

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

  15. Copper removal and nickel for exchange cationic with a natural zeolite

    International Nuclear Information System (INIS)

    Estupinan, Arnoldy; Sarmiento, Diego; Belalcazar de Galvis, Ana Maria

    1998-01-01

    Natural zeolite clinoptilolite, was used to remove copper and nickel from waste waters of a galvanotechnical company. Exchange capacity determined for the zeolite after its transformation to homoionic sodium form, was 0.794 meq/g for copper and 0.447 meq/g for nickel. There were made batch and column experiments, reaching the last one a better approach to the equilibrium. From the degeneration essays, the sodical zeolite concentrates the copper in the waste waters to 23.5 up times the level found for the acid rinsing waters; it shows its potential use in treatment of these waste, because its effectiveness and low cost

  16. The improvement of gas-sensing properties of SnO2/zeolite-assembled composite

    Science.gov (United States)

    Sun, Yanhui; Wang, Jing; Li, Xiaogan; Du, Haiying; Huang, Qingpan

    2018-05-01

    SnO2-impregnated zeolite composites were used as gas-sensing materials to improve the sensitivity and selectivity of the metal oxide-based resistive-type gas sensors. Nanocrystalline MFI type zeolite (ZSM-5) was prepared by hydrothermal synthesis. Highly dispersive SnO2 nanoparticles were then successfully assembled on the surface of the ZSM-5 nanoparticles by using the impregnation methods. The SnO2 nanoparticles are nearly spherical with the particle size of 10 nm. An enhanced formaldehyde sensing of as-synthesized SnO2-ZSM-5-based sensor was observed whereas a suppression on the sensor response to other volatile organic vapors (VOCs) such as acetone, ethanol, and methanol was noticed. The possible reasons for this contrary observation were proposed to be related to the amount of the produced water vapor during the sensing reactions assisted by the ZSM-5 nanoparticles. This provides a possible new strategy to improve the selectivity of the gas sensors. The effect of the humidity on the sensor response to formaldehyde was investigated and it was found the higher humidity would decrease the sensor response. A coating layer of the ZSM-5 nanoparticles on top of the SnO2-ZSM-5-sensing film was thus applied to further improve the sensitivity and selectivity of the sensor through the strong adsorption ability to polar gases and the "filtering effect" by the pores of ZSM-5.

  17. Parametric study on catalytic cracking of LDPE to liquid fuel over ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Wong, S.L.; Tuan Abdullah, T.A.; Ngadi, N.; Ahmad, A.; Inuwa, I.M.

    2016-01-01

    Highlights: • Catalytic cracking of low density polyethylene in fixed bed reactor was studied. • Full factorial design involving five parameters and two responses was used. • Regression models were developed for LDPE conversion and liquid product yield. • Liquid product at optimized run contained C4–C8 aliphatic compounds. • Alkyl radicals combine with minor amount of benzenes during cracking. - Abstract: Pyrolysis or cracking of plastic waste is considered as a potential solution to the environmental problems brought about by plastic waste, with the production of hydrocarbon fuel as a value added benefit. In order to explore the potentials of such process, parametric study have been conducted on the catalytic cracking of LDPE dissolved in benzene in a fixed bed reactor. The five factors studied were temperature (A), catalyst mass (B), feed flow rate (C), carrier gas flow rate (D), as well as concentration of LDPE solution (E), while the responses were LDPE conversion (Y_1) and liquid yield (Y_2). The parametric study showed that four out of five factors (A, B, C and D) have significant effects on Y_1 and Y_2. The optimum conditions that produced maximum responses for Y_1 and Y_2 simultaneously are 600 °C (A), 0.10 g catalyst (B), 1 ml/s LDPE solution (C), 80 ml/min N_2 flow (D). The numerical values for Y_1 and Y_2 were 98.6% and 99.5%, respectively. Analysis on products composition indicated that catalytic cracking of LDPE in fixed bed reaction generally produced high amount of aliphatic branched-chain compounds, together with moderate amount of cyclic compounds. Aromatization of LDPE cracking products is less due to the short retention time of the compounds on the catalysts bed.

  18. Characterization of ZSM-5 zeolites synthesized by amorphous seed method by 29 Si solid state NMR

    International Nuclear Information System (INIS)

    Souza, Claudia M.G. de; Lau, Yiu Lam; Menezes, Sonia Cabral de

    1993-01-01

    The main objective of this analysis was to study the structure of samples synthesised by the amorphous seed method. The implications of this process upon the synthesized material were unknown. In the synthesis it was used ethanol and amorphous seed, which were added to the final synthesis mixture. It was observed a very significant reduction in the reaction time when compared to conventional synthesis. NMR was used to study the defects in the crystal lattice. Results are presented and discussed

  19. Hydrogen output from radiolytic split of water in the presence of some zeolites

    International Nuclear Information System (INIS)

    Cecal, A.; Colisnic, D.; Popa, K.; Paraschivescu, A.; Bilba, N.

    2002-01-01

    Radiolytic decomposition of water under the action of gamma rays in the presence of some zeolites such as ZSM-5, SAPO-5 and MOR was studied. The irradiation was performed using a gamma 60 Co source at an activity of 3 . 10 4 Ci and dose rate 8.3 KGy/h. The stable products of radiolysis as well as the other chemical species were identified by mass spectrometry. The calculated radiochemical yield decreased in order: H-ZSM-5 > Na-ZSM-5 > H-SAPO-5 > MOR and was higher in the presence of these catalysts than in their absence

  20. On the nature of gallium species in gallium-modified mordenite and MFI zeolites. A comparative DRIFT study of carbon monoxide adsorption and hydrogen dissociation.

    Science.gov (United States)

    Serykh, Alexander I; Kolesnikov, Stanislav P

    2011-04-21

    The results of a DRIFT study of carbon monoxide molecular adsorption and hydrogen dissociative adsorption on gallium-modified mordenite and MFI (ZSM-5) zeolites are presented. It was found that in the reduced gallium-modified mordenite (Ga-MOR) both Ga(3+) and Ga(+) exchanged cations are present and can be detected by CO adsorption. Ga(3+) cations in Ga-MOR dissociatively adsorb molecular hydrogen at elevated temperatures, resulting in the formation of gallium hydride species and acidic hydroxyl groups. In the reduced Ga-MFI evacuated at 823 K under medium vacuum conditions only Ga(+) exchanged intrazeolite cations were detected. It was found, however, that Ga(3+) intrazeolite exchanged cations which form upon high-temperature disproportionation of Ga(+) cations in the reduced Ga-MFI and Ga-MOR can be stabilized by high-temperature oxidation of these zeolites.

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

    Science.gov (United States)

    Demirci, Selami; Ustaoğlu, Zeynep; Yılmazer, Gonca Altın; Sahin, Fikrettin; Baç, Nurcan

    2014-02-01

    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.

  2. Crystal dimension of ZSM-5 influences on para selective disproportionation of ethylbenzene.

    Science.gov (United States)

    Hariharan, Srinivasan; Palanichamy, Muthaiahpillai

    2014-03-01

    Crystal size and crystal dimensions are vital role in shape selective feature. Para selective disproportionation of EthylBenzene (Dip-EB) was investigated over ZSM-5 synthesized in acidic medium. The catalysts were prepared by hydrothermal process with various Si/Al ratios (50, 75 and 100) using fluoride ion precursor. This fluoride ion precursor dissolves the ZSM-5 nutrients below it neutral pH between 4 and 6. The synthesized material was subjected into various physico chemical characterizations such as XRD, SEM, TGA and BET analyses. The XRD patterns showed high crystalline nature and their resulting SEM images were also indicate thin prismatic crystals of large dimension compared with alkaline medium synthesized one. The BET results earned good textural property. Catalytic activity of vapor phase Dip-EB was carried out between 523 and 673 K. As their result, diethylbenzene (DEB) isomers were obtained, but para selective Diethylbenzene (p-DEB) was observed higher than others. The high selectivity towards p-DEB was due to large crystal dimension of ZSM-5 catalysts synthesized in fluoride medium. Hence it is good commercial application for petrochemical feed stock production.

  3. A Mesopore-Dependent Catalytic Cracking of n-Hexane Over Mesoporous Nanostructured ZSM-5.

    Science.gov (United States)

    Qamar, M; Ahmed, M I; Qamaruddin, M; Asif, M; Sanhoob, M; Muraza, O; Khan, M Y

    2018-08-01

    Herein, pore size, crystalinity, and Si/Al ratio of mesoporous ZSM-5 (MFI) nanocrystals was controlled by synthesis parameters, such as surfactant concentration ([3-(trimethoxysilyl)propyl] hexa-decyl dimethyl ammonium chloride), sodium hydroxide concentrations, synthesis temperature and time. The morphology, surface structure and composition of the MFI particles was systematically investigated. More notably, the mesopore-dependent catalytic activity of ZSM-5 was evaluated by studying the cracking of n-hexane. The findings suggest the porosity has pronounced impact on the catalytic activity, selectivity and stability of ZSM-5 nanocrystals. Critical surface attributes such as nature of acid sites (Brønsted and Lewis), concentration, and strength are obtained by the infrared study of adsorbed probe molecules (pyridine) and the temperature programmed desorption. In spite of being weaker in Si/Al ratio or acidic strength, mesoporous catalysts showed more stable and efficient cracking of n-hexane suggesting that acidity seems not the predominant factor operative in the activity, selectivity and stability.

  4. Antibacterial properties of Ag-exchanged Philippine natural zeolite-chitosan composites

    Science.gov (United States)

    Taaca, Kathrina Lois M.; Olegario, Eleanor M.; Vasquez, Magdaleno R.

    2017-12-01

    Zeolites are microporous minerals composed of silicon, aluminum and oxygen. These aluminosilicates consist of tetrahedral units which produce open framework structures to generate a system of pores and cavities of molecular dimensions. Zeolites are naturally abundant and can be mined in most parts of the world. In this study, natural zeolites (NaZ) which are locally-sourced here in the Philippines were investigated to determine its properties. An ion-exchange process was utilized, using the zeolite to silver (Ag) solution ratio of 1:20 (w/v), to incorporate Ag into the zeolite framework. Characterizations such as XRD, AAS, and Agar diffusion assay were used to evaluate the properties of the synthesized Ag-exchanged zeolites (AgZ). X-ray diffraction revealed that both NaZ and AgZ have peaks mostly corresponding to the clinoptilolite structure, with some trace peaks of the mordenite and quartz. Absorption spectroscopy revealed that the ion exchange process added about 0.61188g of silver into the zeolite structure. This Ag content was seen to be enough to make the AgZ sample exhibit an antibacterial effect where clearing zones against E. coli and S. aureus were observed in the agar diffusion assay, respectively. The AgZ sample was also tested as ceramic filler to a polymer matrix-chitosan. The diffusion assay revealed presence of antibacterial activity to the polymer composite with AgZ fillers. These results indicate that the Philippine natural zeolite, incorporated with metals such as Ag, can be used as an antibacterial agent and can be developed as a ceramic filler to improve the antibacterial property of composite materials for biomedical application.

  5. On the location, strength and accessibility of Brønsted acid sites in hierarchical ZSM-5 particles

    DEFF Research Database (Denmark)

    Tzoulaki, Despina; Jentys, Andreas; Pérez-Ramírez, Javier

    2012-01-01

    Microporous and mesoporous (hierarchical) ZSM-5 samples, prepared by desilication, dealumination and templating with carbon nanoparticles have been characterized by adsorbing benzene, cyclohexane and 1,3,5-trimethylbenzene (mesitylene) to probe the location, the strength and the accessibility...

  6. Metal-Exchanged β Zeolites as Catalysts for the Conversion of Acetone to Hydrocarbons

    Directory of Open Access Journals (Sweden)

    Aurora J. Cruz-Cabeza

    2012-01-01

    Full Text Available Various metal-β zeolites have been synthesized under similar ion-exchange conditions. During the exchange process, the nature and acid strength of the used cations modified the composition and textural properties as well as the Brönsted and Lewis acidity of the final materials. Zeolites exchanged with divalent cations showed a clear decrease of their surface Brönsted acidity and an increase of their Lewis acidity. All materials were active as catalysts for the transformation of acetone into hydrocarbons. Although the protonic zeolite was the most active in the acetone conversion (96.8% conversion, the metal-exchanged zeolites showed varied selectivities towards different products of the reaction. In particular, we found the Cu-β to have a considerable selectivity towards the production of isobutene from acetone (over 31% yield compared to 7.5% of the protonic zeolite. We propose different reactions mechanisms in order to explain the final product distributions.

  7. Radiochemical and thermal studies of the cation-exchanged forms of synthetic zeolite Linde sieve A

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, S P [Saugar Univ. (India). Dept. of Chemistry

    1976-02-01

    The compositions of the cobalt and silver-exchanged forms of synthetic zeolite Sieve A have been determined by radiochemical and TGA studies and correspond to Co/sub 6/A.19.8H/sub 2/O and Ag/sub 12/..cap alpha... 20H/sub 2/O respectively (A=Al/sub 12/Si/sub 12/O/sub 48//sup 12/-). Heating of these zeolites inhibits their capacity for cation exchange and water absorption. No evidence of occluded NaAlO/sub 2/ has been found.

  8. The structure of actinide ions exchanged into native and modified zeolites and clays

    International Nuclear Information System (INIS)

    Wasserman, S. R.; Soderholm, L.; Giaquinta, D. M.

    2000-01-01

    X-ray absorption spectroscopy (XAS) has been used to investigate the structure and valence of thorium (Th 4+ ) and uranyl (UO 2 2+ ) cations exchanged into two classes of microporous aluminosilicate minerals: zeolites and smectite clays. XAS is also employed to examine the fate of the exchanged cations after modification of the mineral surface using self-assembled organic films and/or exposure to hydrothermal conditions. These treatments serve as models for the forces that ultimately determine the chemical fate of the actinide cations in the environment. The speciation of the cations depends on the pore size of the aluminosilicate, which is fixed for the zeolites and variable for the smectites

  9. Spontaneous dispersion of PdO onto acid sites of zeolites studied by in situ DXAFS

    CERN Document Server

    Okumura, K; Niwa, M; Yokota, S; Kato, K; Tanida, H; Uruga, T

    2003-01-01

    The generation of highly dispersed PdO over zeolite supports was studied using in situ energy-dispersive XAFS (DXAFS) technique. From the comparison with the Na-ZSM-5, it was found that the oxidation as well as the spontaneous dispersion of Pd was promoted through the interaction between PdO and acid sites of H-form zeolites. (author)

  10. Effect of varied quantities of zeolite on the reduction of polycyclic ...

    African Journals Online (AJOL)

    This research was carried out to determine the possibility of total and selective reduction of polycyclic aromatic hydrocarbons (PAHs) content in cigarette smoke by applying different amounts of zeolite directly to the cigarette blend. Zeolite catalysts CuZSM-5 were applied in the form of suspension to the cut tobacco blend in ...

  11. Synthesized TiO{sub 2}/ZSM-5 composites used for the photocatalytic degradation of azo dye: Intermediates, reaction pathway, mechanism and bio-toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Kefu; Hu, Xin-Yan [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chen, Bor-Yann; Hsueh, Chung-Chuan [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan, Taiwan (China); Zhang, Qian [Department of Environmental Engineering, National Taiwan University, Taipei, Taiwan (China); Wang, Jiajie; Lin, Yu-Jung [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chang, Chang-Tang, E-mail: ctchang73222@gmail.com [Department of Environmental Engineering, National I-Lan University, I-Lan, Taiwan (China)

    2016-10-15

    Highlights: • The major photo-catalytic degradation pathway of azo-dye was elaborated according to the identification of by-products from GC–MS and IC analysis. • Comparative assessment on characteristics of abiotic and biotic dye decolorization was analyzed. • EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to determine the main active oxidative species in the system. • The toxicity effects of degradation intermediates of Reactive Black 5 (RB5) on the cellular respiratory activity were assessed. - Abstract: In this study, a one-step solid dispersion method was used to synthesize titanium dioxide (TiO{sub 2})/Zeolite Socony Mobil-5 (ZSM-5) composites with substantially reduced time and energy consumption. A degradation efficiency of more than 95% was achieved within 10 min using 50% PTZ (synthesized TiO{sub 2}/ZSM-5 composites with TiO{sub 2} contents of 50 wt% loaded on ZSM-5) at pH 7 and 25 °C. The possible degradation pathway of azo-dye Reactive Black 5 (RB5) was investigated using gas chromatography–mass spectrometry and ion chromatography (IC). The bonds between the N atoms and naphthalene groups are likely attacked first and cleaved by hydroxyl radicals, ultimately resulting in the decolorization and mineralization of the azo dye. A comparative assessment of the characteristics of abiotic and biotic dye decolorization was completed. In addition, the toxicity effects of the degradation intermediates of azo-dye RB5 on cellular respiratory activity were analyzed. The bio-toxicity results showed that the decay rate constants of CO{sub 2} production from the azo-dye RB5 samples at different degradation times increased initially and subsequently decreased, indicating that intermediates of higher toxicity could adhere to the catalyst surface and gradually destroyed by further photocatalytic oxidation. Additionally, EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system

  12. Selective Synthesis of Gasoline-Ranged Hydrocarbons from Syngas over Hybrid Catalyst Consisting of Metal-Loaded ZSM-5 Coupled with Copper-Zinc Oxide

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2014-04-01

    Full Text Available The conversion of syngas (CO + H2 to gasoline-ranged hydrocarbons was carried out using a hybrid catalyst consisting of metal-loaded ZSM-5 coupled with Cu-ZnO in a near-critical n-hexane solvent. Methanol was synthesized from syngas over Cu-ZnO; subsequently, was converted to hydrocarbons through the formation of dimethyl ether (DME over the metal-loaded ZSM-5. When 0.5 wt% Pd/ZSM-5 and 5 wt% Cu/ZSM-5 among the metal-loaded ZSM-5 catalysts with Pd, Co, Fe or Cu were employed as a portion of the hybrid catalyst, the gasoline-ranged hydrocarbons were selectively produced (the gasoline-ranged hydrocarbons in all hydrocarbons: 59% for the hybrid catalyst with Pd/ZSM-5 and 64% for that with Cu/ZSM-5 with a similar CO conversion during the reaction. An increase in the Cu loading on ZSM-5 resulted in increasing the yield of the gasoline-ranged hydrocarbons, and in decreasing the yield of DME. Furthermore, the hybrid catalyst with Cu/ZSM-5 exhibited no deactivation for 30 h of the reaction. It was revealed that a hybrid catalyst containing Cu/ZSM-5 was efficient in the selective synthesis of gasoline-ranged hydrocarbons from syngas via methanol in the near-critical n-hexane fluid.

  13. Synthesis of high capacity cation exchangers from a low-grade Chinese natural zeolite

    International Nuclear Information System (INIS)

    Wang Yifei; Lin Feng

    2009-01-01

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100 g respectively, which are greatly higher than that of the natural zeolite (97 meq/100 g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca 2+ > K + > Mg 2+ .

  14. Hydrogen cyanide formation in selective catalytic reduction of nitrogen oxides over Cu/ZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, F; Koeppel, R; Baiker, A [Department of Chemical Engineering and Industrial Chemistry, Swiss Federal Institute of Technology, Zurich, (Switzerland)

    1994-01-06

    Hydrogen cyanide is formed over Cu/ZSM-5 during the selective catalytic reduction of NO[sub x] by either propylene or ethylene in the temperature range 450-600 K. Under the reaction conditions used (reactant feed: 973 ppm NO, 907 ppm propene or 1448 ppm ethylene, 2% oxygen, W/F=0.1 g s cm[sup -3]), the concentration of hydrogen cyanide reaches 20, respectively, 30 ppm, depending on whether ethylene or propene are used as hydrocarbons. In addition, significant N[sub 2]O formation is observed at temperatures lower than 700 K, independent of the hydrocarbon used

  15. Removal of pyridine from liquid and gas phase by copper forms of natural and synthetic zeolites

    International Nuclear Information System (INIS)

    Rehakova, Maria; Fortunova, Lubica; Bastl, Zdenek; Nagyova, Stanislava; Dolinska, Silvia; Jorik, Vladimir; Jona, Eugen

    2011-01-01

    Zeoadsorbents on the basis of copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) have been studied taking into account their environmental application in removing harmful pyridine (py) from liquid and gas phase. Sorption of pyridine by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN, X-ray photoelectron spectroscopy, X-ray powder diffractometry, FTIR spectroscopy, thermal analysis (TG, DTA and DTG) and analysis of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(py) x ZSM5, Cu-CT and Cu-(py) x CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine) clearly confirmed their different thermal properties as well as the sorption of pyridine. In the zeolitic pyridine containing samples the main part of the pyridine release process occurs at considerably higher temperatures than is the boiling point of pyridine, which proves strong bond and irreversibility of py-zeolite interaction. FTIR spectra of Cu-(py) x zeolite samples showed well resolved bands of pyridine. The results of thermal analysis and FTIR spectroscopy are in a good agreement with the results of other used methods.

  16. FTIR study of carbon monoxide adsorption on ion-exchanged X, Y and mordenite type zeolites

    Directory of Open Access Journals (Sweden)

    R. HERCIGONJA

    2003-05-01

    Full Text Available In this work Fourier transform infrared (FTIR study has been applied to study the adsorption of carbon monoxide on transition metal (Mn+, Co2+, Ni2+ ion-exchanged zeolites type Y, X and mordenites. The adsorption of CO at room temperature produces overlapping IR absorption bands in the 2120–2200 cm-1 region. The frequency of the band around 2200 cm-1 is found to be dependent not only on the charge-balancing transition metal cation, but also on the framework composition. The frequencies of the band near 1600 cm-1 was found to be dependent on the Si/Al ratio of the investigated zeolites.

  17. Europium-151 Moessbauer spectroscopic and XANES investigation of europium-exchanged Y-zeolite

    International Nuclear Information System (INIS)

    Berry, F.J.; Marco, J.F.; Steel, A.T.

    1994-01-01

    Eu 3+ in ca. 10 wt% europium-exchanged Y-zeolite is partially reduced by treatment in hydrogen at 600 C to Eu 2+ . The reduction of Eu 3+ is more readily achieved in Y-zeolite than in europium(III) oxide. The discrepancy in the extent of reduction as revealed by 151 Eu Moessbauer spectroscopy and near edge X-ray absorption fine structure (XANES) is associated with any difference in the recoil free fractions of Eu 2+ and Eu 3+ which may exist at 298 K and the enhanced sensitivity of the XANES to changes in the europium oxidation state. (orig.)

  18. Radiochemical and thermal studies of the copper(II)-exchanged form of synthetic zeolite linde sieve A

    International Nuclear Information System (INIS)

    Banerjee, S.P.

    1978-01-01

    Synthetic zeolite Linde Sieve A displays a double ion-sieve action. Only small cations can penetrate the single 6-rings into the beta cages. The radiochemical and thermal studies of copper(II)-exchanges form of 4A shows evidence of hydrated copper(II) ions in the zeolite structure. (author)

  19. Catalytic transformation of methyl benzenes over zeolite catalysts

    KAUST Repository

    Al-Khattaf, S.; Akhtar, M. N.; Odedairo, T.; Aitani, A.; Tukur, N. M.; Kubů, M.; Musilová -Pavlačková , Z.; Čejka, J.

    2011-01-01

    experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction

  20. Adsorption of Water and Ethanol in MFI-Type Zeolites

    KAUST Repository

    Zhang, Ke; Lively, Ryan P.; Noel, James D.; Dose, Michelle E.; McCool, Benjamin A.; Chance, Ronald R.; Koros, William J.

    2012-01-01

    Water and ethanol vapor adsorption phenomena are investigated systematically on a series of MFI-type zeolites: silicalite-1 samples synthesized via both alkaline (OH -) and fluoride (F -) routes, and ZSM-5 samples with different Si/Al ratios as well

  1. Redox Catalysis over Metallo-Zeolites. Contribution to Environmental Catalysis

    Czech Academy of Sciences Publication Activity Database

    Wichterlová, Blanka; Sobalík, Zdeněk; Dědeček, Jiří

    2003-01-01

    Roč. 41, - (2003), s. 97-114 ISSN 0926-3373 R&D Projects: GA AV ČR IBS4040016; GA AV ČR IAA4040007 Institutional research plan: CEZ:AV0Z4040901 Keywords : metallo-zeolites * Co-beta * Fe-ZSM-5 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.476, year: 2003

  2. Effect of Zn/ZSM-5 and FePO4 Catalysts on Cellulose Pyrolysis

    Directory of Open Access Journals (Sweden)

    Haian Xia

    2015-01-01

    Full Text Available A series of Zn/ZSM-5 catalysts with different Zn contents and FePO4 were used to pyrolyze cellulose to produce value added chemicals. The nature of these catalysts was characterized by ammonia-temperature programmed desorption (NH3-TPD, IR spectroscopy of pyridine adsorption, and X-ray diffraction (XRD techniques. Noncatalytic and catalytic pyrolytic behaviors of cellulose were studied by thermogravimetric (TG technique. The pyrolytic liquid products, that is, the biooils, were analyzed by gas chromatography-mass spectrometry (GC-MS. The major components of the biooils are anhydrosugars such as levoglucosan (LGA, 1,6-anhydro-β-D-glucofuranose (AGF, levoglucosenone (LGO, 1,6-anhydro-3,4-dideoxy-β-D-pyranosen-2-one, and 1,4:3,6-dianhydro-α-D-glucopyranose (DGP, as well as furan derivatives, alcohols, and so forth. Zn/ZSM-5 samples with Brønsted and Lewis acid sites and the FePO4 catalyst with Lewis acid sites were found to have a significant effect on the pyrolytic behaviors of cellulose and product distribution. These results show that Brønsted and Lewis acid sites modified remarkably components of the biooil, which could promote the production of furan compounds and LGO. On the basis of the findings, a model was proposed to describe the pyrolysis pathways of cellulose catalyzed by the solid acid catalysts.

  3. Optimization of catalytic glycerol steam reforming to light olefins using Cu/ZSM-5 catalyst

    International Nuclear Information System (INIS)

    Zakaria, Z.Y.; Amin, N.A.S.; Linnekoski, J.

    2014-01-01

    Highlights: • Glycerol steam reforming to light olefin using Cu/ZSM-5 process was optimized. • Response surface methodology and multi-objective genetic algorithm were employed. • Second order polynomial model produced adequately fitted experimental data. • Thermodynamic study inferred high temperature requirement for ethylene formation. • Turn-over-frequency at optimized responses is higher than the non-optimized process. - Abstract: Response surface methodology (RSM) and multi-objective genetic algorithm was employed to optimize the process parameters for catalytic conversion of glycerol, a byproduct from biodiesel production, to light olefins using Cu/ZSM-5 catalyst. The effects of operating temperature, weight hourly space velocity (WHSV) and glycerol concentration on light olefins selectivity and yield were observed. Experimental results revealed the data adequately fitted into a second-order polynomial model. The linear temperature and quadratic WHSV terms gave significant effect on both responses. Optimization of both the responses indicated that temperature favouring high light olefin formation lied beyond the experimental design range. The trend in the temperature profile concurred commensurately with the thermodynamic analysis. Multi-objective genetic algorithm was performed to attain a single set of processing parameters that could produce both the highest light olefin selectivity and yield. The turn-over-frequency (TOF) of the optimized responses demonstrated a slightly higher value than the one which was not optimized. Combination of RSM, multi-objective response and thermodynamic is useful to determine the process optimal operating conditions for industrial applications

  4. [Adsorption characteristics of acetone and butanone onto honeycomb ZSM-5 molecular sieve].

    Science.gov (United States)

    Du, Juan; Luan, Zhi-Qiang; Xie, Qiang; Ye, Ping-Wei; Li, Kai; Wang, Xi-Qin

    2013-12-01

    Adsorption capacity of acetone and acetone-butanone mixture onto honeycomb ZSM-5 molecular sieve was measured in this paper, and the influences of relative humidity, initial adsorbate concentration and airflow velocity on the adsorption process were investigated. Besides, adsorption performance parameters were calculated by Wheeler's equation. The results showed that relative humidity had no obvious influence on the acetone adsorption performance, which suggests that this material has good hydrophobic ability; in the low concentration range, the dynamic saturated adsorption capacity of acetone increased with the increase of initial concentration, but in the occasion of high concentration of acetone gas (more than 9 mg x L(-1)), the dynamic saturated adsorption capacity maintained at a certain level and did not vary with the increase of initial concentration; the increase of air flow velocity resulted in significant increase of acetone adsorption rate constant, at the same time the critical layer thickness of the adsorbent bed also increased significantly. In the cases of acetone-butanone mixture, the adsorption capacity of butanone onto ZSM-5 was clearly higher than that of acetone.

  5. Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment

    Science.gov (United States)

    Aguilar-Mamani, Wilson; Akhtar, Farid; Hedlund, Jonas; Mouzon, Johanne

    2018-04-01

    The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

  6. The Effect of Zeolite Composition and Grain Size on Gas Sensing Properties of SnO2/Zeolite Sensor

    Directory of Open Access Journals (Sweden)

    Yanhui Sun

    2018-01-01

    Full Text Available In order to improve the sensing properties of tin dioxide gas sensor, four kinds of different SiO2/Al2O3 ratio, different particle size of MFI type zeolites (ZSM-5 were coated on the SnO2 to prepared zeolite modified gas sensors, and the gas sensing properties were tested. The measurement results showed that the response values of ZSM-5 zeolite (SiO2/Al2O3 = 70, grain size 300 nm coated SnO2 gas sensors to formaldehyde vapor were increased, and the response to acetone decreased compared with that of SnO2 gas sensor, indicating an improved selectivity property. The other three ZSM-5 zeolites with SiO2/Al2O3 70, 150 and 470, respectively, and grain sizes all around 1 μm coated SnO2 sensors did not show much difference with SnO2 sensor for the response properties to both formaldehyde and acetone. The sensing mechanism of ZSM-5 modified sensors was briefly analyzed.

  7. Local structure of Pb2 ion catalysts anchored within zeolite cavities and their photo-catalytic reactivity for the elimination of N2O

    International Nuclear Information System (INIS)

    Ju, Woo-Sung; Matsuoka, Masaya; Yamashita, Hiromi; Anpo, Masakazu

    2001-01-01

    The Pb 2+ /ZSM-5 catalyst was prepared by an ion-exchange method and its photo-catalytic activity for the decomposition of N 2 O under UV irradiation was investigated. In-situ UV-Vis absorption spectroscopy and XAFS (XANES and FT-EXAFS) investigations revealed that the Pb 2+ ions exist in a highly dispersed state within the pores of the zeolites. UV irradiation of the catalysts in the presence of N 2 O led to the photo-catalytic decomposition of N 2 O into N 2 at temperatures as low as 298κ. The effective wavelength of the irradiated UV light indicated that the excited state of the Pb 2+ ions included within the zeolite cavities plays a significant role in the photo-catalytic decomposition of N 2 O molecules. (au)

  8. Controlled growth of gold nanoparticles in zeolite L via ion-exchange reactions and thermal reduction processes

    KAUST Repository

    Zeng, Shangjing; Ding, Shuang; Li, Shangyu; Wang, Runwei; Zhang, Zongtao

    2014-01-01

    The growth of gold nanoparticles in zeolite can be controlled using ion-exchange reactions and thermal reduction processes. We produce a number of different sizes of the gold nanoparticles with the particle size increasing with increased temperature

  9. Evaluation of Silver-Exchanged Zeolites Under Development by University of Maine for Chemical Warfare Agent Decontamination Applications

    National Research Council Canada - National Science Library

    Brickhouse, Mark D; Lalain, Teri A; D'Onofrio, Terrence G; Procell, Lawrence R; Zander, Zachary B

    2007-01-01

    This effort is for the evaluation of a non-toxic photo-catalytic decontamination technology based on silver-exchanged zeolites being developed by the University of Maine research team under the direction of Dr. Howard H...

  10. Catalytic transformation of methyl benzenes over zeolite catalysts

    KAUST Repository

    Al-Khattaf, S.

    2011-02-01

    Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over ZSM-5, TNU-9, mordenite and SSZ-33 catalysts in a novel riser simulator at different operating conditions. Catalytic experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction conditions on the isomerization to disproportionation product ratio, distribution of trimethylbenzene (TMB) isomers, and p-xylene/o-xylene ratios are reported. The sequence of reactivity of the three alkyl benzenes depends upon the pore structure of zeolites. The zeolite structure controls primarily the diffusion of reactants and products while the acidity of these zeolites is of a secondary importance. In the case of medium pore zeolites, the order of conversion was m-xylene > 1,2,4-TMB > toluene. Over large pore zeolites the order of reactivity was 1,2,4-TMB > m-xylene > toluene for SSZ-33 catalyst, and m-xylene ∼ 1,2,4-TMB > toluene over mordenite. Significant effect of pore size between ZSM-5 and TNU-9 was observed; although TNU-9 is also 3D 10-ring channel system, its slightly larger pores compared with ZSM-5 provide sufficient reaction space to behave like large-pore zeolites in transformation of aromatic hydrocarbons. We have also carried out kinetic studies for these reactions and activation energies for all three reactants over all zeolite catalysts under study have been calculated. © 2011 Elsevier B.V.

  11. Characterization of zeolites by magic-angle-spinning NMR

    International Nuclear Information System (INIS)

    Brunner, E.; Ernst, H.; Freude, D.; Hunger, M.; Pfeifer, H.

    1988-01-01

    Magic-angle-spinning nuclear magnetic resonance (MAS NMR) has been used to study structure defects in TPA/ZSM-5, the dealumination process caused by hydrothermal treatment and acid leaching of zeolites, the influence of Lewis sites upon water as a probe molecule, the boron incorporation into the ZSM-5 framework, and the acid sites and structure defects in SAPO-5. The nuclei under study are 1 H, 11 B, 27 Al, 29 Si, and 31 P. 24 refs.; 7 figs.; 1 table

  12. Ion exchange of Cobalt and Cadmium in Zeolite X

    International Nuclear Information System (INIS)

    Nava M, I.

    1994-01-01

    The growing development in the industry has an important contribution to the environmental damage, where the natural effluents are each day more contaminated by toxic elements, such as: mercury, chromium, lead and cadmium. So as to separate such elements it has sorbent must have enough stability, and have a sharp capacity of sorption. In this work it was studied the sorption behavior of cobalt and on the other hand, cadmium in aqueous solutions, which along with sodic form of the Zeolite X, undergoes a phenomenon of ionic interchange. Such interchange was verify to different concentration of cadmium, cobalt and hydronium ion. The content of cobalt and sodium in the interchanged samples was detected through the neutronic activation analysis. The results disclose a higher selectivity for cadmium than cobalt. (Author)

  13. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

  14. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

    International Nuclear Information System (INIS)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-01-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

  15. Synthesis of biodiesel using local natural zeolite as heterogeneous anion exchange catalyst

    Science.gov (United States)

    Hartono, R.; Wijanarko, A.; Hermansyah, H.

    2018-04-01

    Production of biodiesel using homogen catalyst: alkaline catalysts, acid catalysts, biocatalysts, and supercritical methanol are very inefficient, because these catalysts have a very high cost production of biodiesel and non-ecofriendly. The heterogeneous catalyst is then used to avoid adverse reaction of biodiesel production. The heterogeneous catalysts used is ion exchanger using natural zeolit catalists bayah banten (ZABBrht) and macroporous lewatit that can be used to produce biodiesel in the solid phase so that the separation is easier and can be used repeatedly. The results of biodiesel reach its optimum in engineering ion exchange catalyst natural zeolit bayah and macroporous lewatit which has been impregnated and calcinated at temperature 60 °C at reaction time 2 hours, are 94.8% and 95.24%, using 100 gr.KOH/100 mL Aquadest.

  16. Hydrothermal preparation of zeolite Li-A and ion exchange properties of Cs and Sr in salt waste

    International Nuclear Information System (INIS)

    Lee, S. H.; Kim, J. G.; Lee, J. H.; Kim, J. H.

    2005-01-01

    An advanced spent fuel management process that were based on Li reduction of the oxide spent fuel to a metallic form will generate a LiCl waste. Zeolite A has been reported as a promising immobilization medium for waste salt with CsCl and SrCl 2 . However, Sodium is accumulated as an ionic form (Na + -ion) in molten salt during ion exchange step between Na + -ion in zeolite A and Li + -ion in the molten salt. Therefore, zeolite Na-A need to be replaced by the Li-type zeolite for recycling the salt waste by removing the Cs and Sr ions. In this study, the hydrothermal preparation of zeolite Li-A was performed in 350ml pressure vessel by P. Norby method. The preparation characteristics of zeolite Li-A was investigated. And the ion exchange properties of Cs and Sr in molten LiCl salt were investigated under the condition of 923K using zeolite 4A and prepared zeolite Li-A

  17. A comparative study on the quality of bio-oil derived from green macroalga Enteromorpha clathrata over metal modified ZSM-5 catalysts.

    Science.gov (United States)

    Wang, Shuang; Cao, Bin; Liu, Xinlin; Xu, Lujiang; Hu, Yamin; Afonaa-Mensah, Stephen; Abomohra, Abd El-Fatah; He, Zhixia; Wang, Qian; Xu, Shannan

    2018-05-01

    The green macroalga Enteromorpha clathrata was pyrolyzed with or without catalysts at the temperature of 550 °C for producing high-quality bio-oil. The ZSM-5 and 1,2,3 mmol Mg-Ce/ZSM-5 catalysts were introduced to investigate the yields and components distribution of bio-oil. Increase of bio-oil production was obtained with the use of ZSM-5 and 1,2,3 mmol Mg-Ce/ZSM-5 catalysts. The 1 mmol Mg-Ce/ZSM-5 catalyst exhibited more promising property for promoting the relative content of C 5 -C 7 compounds, and decreasing the relative content of acids in bio-oil. The results suggested that E. clathrata had potential as pyrolysis feedstocks for producing the high-quality bio-oil with large amounts of C 5 -C 7 compounds and low relative content of acids when the 1 mmol Mg-Ce/ZSM-5 catalyst was used. Furthermore, the physicochemical properties of ZSM-5 and 1 mmol Mg-Ce/ZSM-5 catalysts were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed desorption of ammonia. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Study of iron exchanged zeolites by Moessbauer effect and electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Aguirre Campuzano, C.E.

    1993-01-01

    Crystalline iron exchanged NaY zeolites, prepared from aqueous solutions and calcined at atmospheric conditions, have been studied and characterized by XRD, Moessbauer and EPR spectroscopies and TGA analysis. Three iron sites are clearly distinguished from Moessbauer and EPR measurements. Firstly, characteristic Moessbauer and EPR spectra may arise from framework sites, suggesting that Fe has substituted Al. It is also found that their spectroscopic signals are not intensity affected by thermal treatments. Secondly, a Moessbauer doublet which may arise from octahedral sites in the large cavity of the zeolite, shows however, that this doublet and its EPR signal are intensity temperature affected. An additional line broadening is observed on the low velocity line of this doublet, Thirdly, characteristic Moessbauer and EPR signals, which are also intensity temperature dependent have been associated to accluded material, where the Moessbauer doublet presents the line broadening effect before mentioned. Such line broadening effect may be due to perturbing signals from iron ions in tetrahedral sites. Finally, it has been observed that during calcination of the FeY zeolites, the three characteristic EPR signals for the three iron sites, do not increase at the expenses of the other. A result that may suggest a strong bonding between Fe-site of the Y zeolite, irrespective of the iron source. (Author)

  19. Tracing compartment exchange by NMR diffusometry: Water in lithium-exchanged low-silica X zeolites

    Science.gov (United States)

    Lauerer, A.; Kurzhals, R.; Toufar, H.; Freude, D.; Kärger, J.

    2018-04-01

    The two-region model for analyzing signal attenuation in pulsed field gradient (PFG) NMR diffusion studies with molecules in compartmented media implies that, on their trajectory, molecules get from one region (one type of compartment) into the other one with a constant (i.e. a time-invariant) probability. This pattern has proved to serve as a good approach for considering guest diffusion in beds of nanoporous host materials, with the two regions ("compartments") identified as the intra- and intercrystalline pore spaces. It is obvious, however, that the requirements of the application of the two-region model are not strictly fulfilled given the correlation between the covered diffusion path lengths in the intracrystalline pore space and the probability of molecular "escape" from the individual crystallites. On considering water diffusion in lithium-exchanged low-silica X zeolite, we are now assuming a different position since this type of material is known to offer "traps" in the trajectories of the water molecules. Now, on attributing the water molecules in the traps and outside of the traps to these two types of regions, we perfectly comply with the requirements of the two-region model. We do, moreover, benefit from the option of high-resolution measurements owing to the combination of magic angle spinning (MAS) with PFG NMR. Data analysis via the two-region model under inclusion of the influence of nuclear magnetic relaxation yields satisfactory agreement between experimental evidence and theoretical estimates. Limitations in accuracy are shown to result from the fact that mass transfer outside of the traps is too complicated for being adequately reflected by simple Fick's laws with but one diffusivity.

  20. Zeolites for nitrosamine and pharmaceutical removal from demineralised and surface water: Mechanisms and efficacy

    KAUST Repository

    De Ridder, David J.

    2012-03-01

    Zeolites with a high Si/Al ratio can be used as selective adsorbents in water treatment, targeting organic micropollutants which are removed poorly with activated carbon. Due to size exclusion, many Natural Organic Matter (NOM) components cannot access the pores, thus limiting adsorption competition between organic micropollutant and NOM. Furthermore, zeolite channel diameters are close to molecule diameters, which results in strong van der Waals interaction. MOR200 and ZSM5, the two most hydrophobic zeolites, showed the highest removal of neutral nitrosamines in demineralised water, with higher efficacy than activated carbon. DAY and MOR30, which were relatively hydrophilic zeolites, did not show appreciable removal of any of the nitrosamines. When nitrosamines were adsorbed from surface water, there was no influence of competition with, or pore blockage by, NOM components on nitrosamine removal for ZSM5 zeolite, in contrast to activated carbon. Repulsion of negatively charged pharmaceuticals was significant for ZSM5, which had a Si/Al ratio of 80. MOR200 had a Si/Al ratio of 200, indicating a lower Al content than ZSM5 and, as such, a lower negative surface charge. Charge effects were not observed for MOR200. A relationship was found between the Stokes diameter of the pharmaceuticals and nitrosamines, and their removal by ZSM5 and MOR200, indicating that a "close fit" adsorption mechanism is more likely than hydrophobic interaction in these zeolites. Due to their selective nature, adsorption on zeolites should only be considered as an additional treatment step to existing processes, dedicated for the removal of specific organic micropollutants. Less specific treatment techniques, such as activated carbon filtration, are still required to ensure a broad barrier for organic micropollutants in water treatment. © 2012 Elsevier B.V. All rights reserved.

  1. High-throughput preparation and testing of ion-exchanged zeolites

    International Nuclear Information System (INIS)

    Janssen, K.P.F.; Paul, J.S.; Sels, B.F.; Jacobs, P.A.

    2007-01-01

    A high-throughput research platform was developed for the preparation and subsequent catalytic liquid-phase screening of ion-exchanged zeolites, for instance with regard to their use as heterogeneous catalysts. In this system aqueous solutions and other liquid as well as solid reagents are employed as starting materials and 24 samples are prepared on a library plate with a 4 x 6 layout. Volumetric dispensing of metal precursor solutions, weighing of zeolite and subsequent mixing/washing cycles of the starting materials and distributing reaction mixtures to the library plate are automatically performed by liquid and solid handlers controlled by a single common and easy-to-use programming software interface. The thus prepared materials are automatically contacted with reagent solutions, heated, stirred and sampled continuously using a modified liquid handling. The high-throughput platform is highly promising in enhancing synthesis of catalysts and their screening. In this paper the preparation of lanthanum-exchanged NaY zeolites (LaNaY) on the platform is reported, along with their use as catalyst for the conversion of renewables

  2. Zeolite synthesis from the pyrrolidine containing system and their catalytic properties in the methanol conversion reaction

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kunio; Kiyozumi, Yoshimichi; Shin, Shigemitsu; Ogawa, Kiyoshi; Yamazaki, Yasuyoshi; Watanabe, Hideo

    1987-12-18

    Systhesis of zeolite from a system containing cheaper pyrrolidine as a crystallization regulator than quaternary ammonium ion was carried out and the methanol conversion reaction was studied over the systhesized zeolite to get C/sub 2/ and C/sub 3/ olefins. Hydrous gels were prepared by adding and agitating pyrrolidine, water glass and sulfuric acid to aluminum sulfate solution; and aluminum nitrate, colloidal silica and pyrrolidine to NaOH solution. Five zeolite, that is, ZSM-5, ZSM-35, ZSM-39, ZSM-48 and KZ-1 were synthesized by changing gel components. X-ray powder diffraction, BET specific surface areas, micropore diameters, micropore volumes, oxygen contents by scanning electron photomicrographs and infra-red spectra were examined. The organic base in hydrous gels influenced greatly on the zeolite composition and structure. The ZSM-5 zeolite exhibited the superior performance as to a high selectivity of light olefins over the target of development. (12 figs, 1 tab, 20 refs)

  3. High ion-exchange properties of hybrid materials from X-type zeolite and ground glass powder

    Science.gov (United States)

    Taira, Nobuyuki; Yoshida, Kohei

    2017-10-01

    Zeolites are crystalline aluminosilicates with a homogeneous distribution of micropores with a superior cation-exchange capacity. Because they have especially excellent selective exchange properties, a considerable number of studies have been conducted on treating water containing radioisotopes using the zeolites. When using artificial zeolites, they have inferior sinterability; in addition, it is quite hard for them to remove from polluted liquid since these artificial zeolites are principally synthesized as a form of powder, which is a disadvantage. In this study, hybrid materials were prepared from X-type zeolite and waste glass powder. Their ion-removal effect and mechanical strength were investigated. The zeolite and waste glass were ground in an agate mortar in several ratios. 0.5 g of the mixture was pressure-molded into pellets having a diameter of 7 mm. These pellets were slowly heated at the speed of 240°C/h to 700°C and maintained at 700°C for 2 h. The removal rate of Sr2+ ions increased as the amount of X-type zeolite in the hybrid materials increased; the former increased up to 100% when the content of latter exceeded 50%. The mechanical strength increased by increasing the amount of glass in the hybrid materials. This is attributed to the fact that the glass powder acts as a binder that improves the densification and consequently the mechanical strength of the hybrid materials.

  4. The selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hun Hwee; Min, Byeog Heon [Hoseo University, Taegu (Korea)

    1998-04-01

    This study shows the selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites such as clinoptilolite, Y-type CBV760, CBV780 and A-type 3A. The selective separation of Cs and Sr on these zeolites was examined using batch and continuous column experiments. For the selective separation of Cs and Sr from a synthetic wastewater, adsorption rate of Cs increased in the order, clinoptilolite> 3A>> CBV760> CBV780, adsorption rate of Sr increased in the other, 3A>> clinoptilolite> CBV760> CBV780. For the clinoptilolite, the adsorption rate of Cs reached about 96 {approx} 98% within 3h. The adsorption rate of Sr on 3A reached about 99% within 3h. (author). 40 refs., 27 figs., 4 tabs.

  5. OBTAINING OF THE MG2+ FORM OF THE ZEOLITE 4A WITH ION EXCHANGE OF MAGNESIUM SALTS

    Directory of Open Access Journals (Sweden)

    Blagica Cekova

    2016-01-01

    Full Text Available Zeolites are sodium alumino silicates which in in their composition contain zeolite water. They have a three-dimensional structure. Spatial structure defined by a strictly defined geometry of pores and cavities. For ionic еchange is used magnesium salt (MgCl2*6H2O whose aqueous solutions were with the following concentrations (MgCl2*6H2O = 2,5; 3.5; 4,5 mol / dm3 , and other parameters of the ion exchange: time t = 20, 30, 40 and temperature of 298 and 330 K. Ionian capacity is calculated as mmgMgO / 1g zeolite.

  6. Evidence for F-/SiO- anion exchange in the framework of As-synthesized all-silica zeolites

    KAUST Repository

    Liu, Xiaolong

    2011-05-12

    Not everything changes: Charge-compensating anions can be exchanged in as-synthesized zeolite frameworks with changes in both the density of defect sites and of the hydrophobic character of the zeolite. The reversible transformation occurs without dissolution/recrystallization of the zeolite and preserves the size and shape of the crystals (see picture). Fluoride removal is not possible in all-silica D4R units, for which fluoride ions play a structure-directing role. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Molecular exchange of n-hexane in zeolite sieves studied by diffusion-diffusion and T{sub 1}-diffusion nuclear magnetic resonance exchange spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Neudert, Oliver; Stapf, Siegfried; Mattea, Carlos, E-mail: carlos.mattea@tu-ilmenau.de [Fachgebiet Technische Physik II/Polymerphysik, Institute of Physics, Technische Universitaet Ilmenau, PO Box 100 565, 98684 Ilmenau (Germany)

    2011-03-15

    Molecular exchange properties and diffusion of n-hexane embedded in a bimodal pore structure with characteristic length scales in the order of nano and micrometres, respectively, formed by packing of zeolite particles, are studied. Two-dimensional (2D) nuclear magnetic resonance (NMR) diffusion correlation experiments together with relaxation-diffusion correlation experiments are performed at low magnetic field using a single-sided NMR scanner. The exchange time covers a range from 10{sup -3} to 10{sup -1} s. The molecular exchange properties are modulated by transport inside the zeolite particles. Different exchange regimes are observed for molecules starting from different positions inside the porous sample. The influence of the spin-lattice relaxation properties of the fluid molecules inside the zeolite particles on the signal intensity is also studied. A Monte Carlo simulation of the exchange process is performed and is used to support the analysis of the experimental data.

  8. Towards a methanol economy: Zeolite catalyzed production of synthetic fuels

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie

    The main focus of this thesis is zeolite catalyzed conversion of oxygenates to hydrocarbon fuels and chemicals. Furthermore, conversion of ethane to higher hydrocarbons has also been studied. After a brief introduction to the concept of “the methanol economy” in the first chapter, the second...... a commercial H-ZSM-5 zeolite impregnated with gallium and/or molybdenum is described. The object was to investigate if the presence of methanol in the feed could enhance the conversion of ethane, but in all cases the opposite is observed; the presence of methanol actually suppresses the conversion of ethane...... various zeolite catalysts is studied in Chapter 4. When 2-propanol or 1-butanol is converted over H-ZSM-5, the total conversion capacities of the catalyst are more than 25 times higher than for conversion of methanol and ethanol. Furthermore, for conversion of C3+ alcohols, the selectivity shifts during...

  9. HYDROPHOBIC ZEOLITE-SILICONE RUBBER MIXED MATRIX MEMBRANES FOR ETHANOL-WATER SEPARATION: EFFECT OF ZEOLITE AND SILICONE COMPONENT SELECTION ON PERVAPORATION PERFORMANCE

    Science.gov (United States)

    High-silica ZSM 5 zeolites were incorporated into poly(dimethyl siloxane) (PDMS) polymers to form mixed matrix membranes for ethanol removal from water via pervaporation. Membrane formulation and preparation parameters were varied to determine the effect on pervaporation perform...

  10. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

    Science.gov (United States)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Zeolite and wollastonite synthesis from rice hull ash; Sintese de zeolitas e wolastonita a partir da cinza da casca de arroz

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Alberto de Andrade

    2006-07-01

    Rice hull ash (RHA) is a industry scrap rich in amorphous silica. A simple and low-energy cost method for the extraction of this silica was researched. A low level of impurity and high reactivity material was produced, which is appropriate for the synthesis of zeolites and wollastonite (CaSiO{sub 3}). The synthetic zeolites has not similar structures in nature, and they have been more and more valued in the market due to their purity and efficiency in specific applications like ion exchange, molecular sieve and catalysis areas. High purity wollastonite has many applications in manufacturing and agriculture. The mineral wollastonite can be formed in nature in different ways; it is generally accepted two forming processes, both encompassing limestone metamorphism (heat and pressure). In this work, a new process for the synthesis of zeolites and wollastonite from RHA colloidal silica was developed. Moreover, the process is aimed at lower energy costs, fewer stages and fewer reactants consume. In this work, zeolite A used in detergent and zeolite ZSM-5, employed in the petrochemical industry due to its high selectivity in catalytic reactions and its high thermo and acid stability, were synthesized. The first step of the wollastonite synthesis was studied, with the purpose of obtaining calcium hydrosilicate. Eleven different hydrosilicates occur in the system Ca(OH){sub 2}-SiO{sub 2}-H{sub 2}O, in the second step it was annealed to form the wollastonite phase. (author)

  12. Beyond Creation of Mesoporosity: The Advantages of Polymer-Based Dual-Function Templates for Fabricating Hierarchical Zeolites

    KAUST Repository

    Tian, Qiwei

    2016-02-05

    Direct synthesis of hierarchical zeolites currently relies on the use of surfactant-based templates to produce mesoporosity by the random stacking of 2D zeolite sheets or the agglomeration of tiny zeolite grains. The benefits of using nonsurfactant polymers as dual-function templates in the fabrication of hierarchical zeolites are demonstrated. First, the minimal intermolecular interactions of nonsurfactant polymers impose little interference on the crystallization of zeolites, favoring the formation of 3D continuous zeolite frameworks with a long-range order. Second, the mutual interpenetration of the polymer and the zeolite networks renders disordered but highly interconnected mesopores in zeolite crystals. These two factors allow for the synthesis of single-crystalline, mesoporous zeolites of varied compositions and framework types. A representative example, hierarchial aluminosilicate (meso-ZSM-5), has been carefully characterized. It has a unique branched fibrous structure, and far outperforms bulk aluminosilicate (ZSM-5) as a catalyst in two model reactions: conversion of methanol to aromatics and catalytic cracking of canola oil. Third, extra functional groups in the polymer template can be utilized to incorporate desired functionalities into hierarchical zeolites. Last and most importantly, polymer-based templates permit heterogeneous nucleation and growth of mesoporous zeolites on existing surfaces, forming a continuous zeolitic layer. In a proof-of-concept experiment, unprecedented core-shell-structured hierarchical zeolites are synthesized by coating mesoporous zeolites on the surfaces of bulk zeolites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Comparative Study Between Ethylbenzene Disproportionation Reaction and its Ethylation Reaction with Ethanol over ZSM-5

    KAUST Repository

    Tukur, N. M.

    2009-06-23

    Ethylation of ethylbenzene with ethanol has been studied over ZSM-5 catalyst in a riser simulator that mimics the operation of a fluidized-bed reactor. The feed molar ratio of ethylbenzene:ethanol is 1:1. The study was carried out at 350, 400, 450, and 500°C for reaction times of 3, 5, 7, 10, 13, and 15 s. Comparisons are made between the results of the ethylbenzene ethylation reaction with that of ethylbenzene disproportionation reaction earlier reported. The effect of reaction conditions on ethylbenzene reactivity, p-diethylbenzene selectivity, total diethylbenzene (DEB) isomers selectivity, p-DEB-to-m-DEB ratio, benzene-to-DEB molar ratio, and benzene selectivity, are reported. Benzene selectivity is about 10 times more in the EB disproportion reaction as compared to its ethylation reaction with ethanol at 350°C. In addition, the results showed a p-DEB/m-DEB ratio for the EB ethylation reaction varying between 1.2-1.7, which is greater than the equilibrium values. Increase in temperature shifts the alkylation/dealkylation equilibrium towards dealkylation, thereby decreasing conversion and selectivity to DEB. © Springer Science+Business Media, LLC 2009.

  14. BIOFUEL PRODUCTION FROM PALM OLEIN BY CATALYTIC CRACKING PROCESS USING ZSM-5 CATALYST

    Directory of Open Access Journals (Sweden)

    Rondang Tambun

    2017-06-01

    Full Text Available The depletion of fossil energy reserves raises the potential in the development of renewable fuels from vegetable oils. Indonesia is the largest palm oil producer in the world, where palm oil can be converted into biofuels such as biogasoline, kerosene and biodiesel. These biofuels are environmentally friendly and free of the content of nitrogen and sulfur through catalytic cracking process. In this research, palm olein is used as feedstock using catalytic cracking process. ZSM-5 is used as a catalyst, which has a surface area of 425 m2/g and Si/Al ratio of 50. Variables varied are the operating temperature of 375 oC - 450 °C and reaction time of 60 minutes - 150 minutes. The result shows that the highest yield of liquid product is 84.82%. This yield is obtained at a temperature of 400 °C and reaction time of 120 minutes. The yield of the liquid product in the operating conditions consisting of C6-C12 amounted to 19.47 %, C14-C16 amounted to 16.56 % and the C18-C28 amounted to 48.80 %.

  15. Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcanti, Rodrigo M.; Barros, Ivoneide de C.L., E-mail: ibarros@ufam.edu.br [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Inst. de Ciencias Exatas; Dias, Jose A.; Dias, Silvia C.L. [Universidade de Brasilia (UnB), DF (Brazil). Inst. de Quimica

    2013-01-15

    ZSM-5 adsorbents impregnated with Nb{sub 2}O{sub 5} were applied in the sulfur removal in the form of thiophene, refractory substance of difficult removal of liquid fuels. For this purpose, a model fuel containing iso-octane contaminated with thiophene in concentrations of 877.5 to 1155 ppmw was prepared. The samples were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR) and Fourier transform-Raman (FT-Raman) spectroscopies for confirmation of the adsorbents, being prioritized the adsorption study with that containing 5 wt.% of niobium pentoxide, because it showed a greater capacity for removal of thiophene. The best results of adsorption were achieved at 353 K, a longer time to reach equilibrium was observed. Under these conditions, the best kinetic fitting was achieved using the equation of pseudo-second order, demonstrating the domain of the phenomenon of chemisorption. While under lower temperatures, the diffusion model presented a better approximation of the experimental results. Also, the increasing of temperature did enhance spontaneous processes. (author)

  16. High-Flux Zeolitic Imidazolate Framework Membranes for Propylene/Propane Separation by Postsynthetic Linker Exchange.

    Science.gov (United States)

    Lee, Moon Joo; Kwon, Hyuk Taek; Jeong, Hae-Kwon

    2018-01-02

    While zeolitic imidazolate framework, ZIF-8, membranes show impressive propylene/propane separation, their throughput needs to be greatly improved for practical applications. A method is described that drastically reduces the effective thickness of ZIF-8 membranes, thereby substantially improving their propylene permeance (that is, flux). The new strategy is based on a controlled single-crystal to single-crystal linker exchange of 2-methylimidazole in ZIF-8 membrane grains with 2-imidazolecarboxaldehyde (ZIF-90 linker), thereby enlarging the effective aperture size of ZIF-8. The linker-exchanged ZIF-8 membranes showed a drastic increase in propylene permeance by about four times, with a negligible loss in propylene/propane separation factor when compared to as-prepared membranes. The linker-exchange effect depends on the membrane synthesis method. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Isotopic exchange kinetics of zinc ions in Zn-A zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Radak, V M; Gal, I J; Salai, J J [Belgrade Univ. (Yugoslavia)

    1976-01-01

    The isotopic exchange kinetics of Zn/sup 2 +/ ions in hydrated Zn-A zeolite of composition (Znsub(5.55)Nasub(0.90)(A10/sub 2/)/sub 12/(Si0/sub 2/)/sub 12/.aq) have been investigated by measuring the fractional attainment of isotopic equilibrium between a ZnCl/sub 2/ solution and a /sup 65/Zn-labelled Zn-A zeolite (30 and 45 ..mu..m particle radii) as a function of time, in the temperature range 25 to 60/sup 0/C. The exchange mechanism is a two-step process which has been resolved, using the Brown-Sherry-Krambeck model (J.Phys.Chem.;75:3846(1971)) into diffusion in the solid particles, with Zn/sup 2 +/ diffusivity of D = 10sup(-3.97 + -0.03) exp(-Esub(D)/RT)m/sup 2/ s/sup -1/, Esub(D) = 67.1 +- 0.5 kJ molee/sup -1/, and an intracrystalline first-order exchange between bound and mobile Zn/sup 2 +/ ions in the network, with a rate constant of k/sub 2/ = 10sup(3.05 +- 0.25) exp(-Esub(k)/RT)s/sup -1/, Esub(k) = 56.5 +- 1.5 kJ mol/sup -1/.

  18. Factors affecting alcohol-water pervaporation performance of hydrophobic zeolite-silicone rubber mixed matrix membranes

    Science.gov (United States)

    Mixed matrix membranes (MMMs) consisting of ZSM-5 zeolite particles dispersed in silicone rubber exhibited ethanol-water pervaporation permselectivities up to 5 times that of silicone rubber alone and 3 times higher than simple vapor-liquid equilibrium (VLE). A number of conditi...

  19. Removal of pyridine from liquid and gas phase by copper forms of natural and synthetic zeolites

    Czech Academy of Sciences Publication Activity Database

    Reháková, M.; Fortunová, L.; Bastl, Zdeněk; Nagyová, S.; Dolinská, S.; Jorík, V.; Jóna, E.

    2011-01-01

    Roč. 186, č. 1 (2011), s. 699-706 ISSN 0304-3894 R&D Projects: GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : natural zeolite * clinoptilolite * ZSM5 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.173, year: 2011

  20. Characterization of the Cu+ sites in MFI zeolites: combined computational and experimental study

    Czech Academy of Sciences Publication Activity Database

    Bludský, Ota; Nachtigall, Petr; Čičmanec, P.; Knotek, P.; Bulánek, R.

    2005-01-01

    Roč. 100, - (2005), 385-389 ISSN 0920-5861 R&D Projects: GA MŠk(CZ) LN00A032 Institutional research plan: CEZ:AV0Z40550506 Keywords : ZSM-5 zeolite * carbon-monoxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.365, year: 2005

  1. Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

    Science.gov (United States)

    Zhokh, Alexey A.; Strizhak, Peter E.

    2018-01-01

    H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

  2. Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

    Science.gov (United States)

    Zhokh, Alexey A.; Strizhak, Peter E.

    2018-07-01

    H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

  3. for zeolite coating

    Directory of Open Access Journals (Sweden)

    Carlos Renato Rambo

    2006-01-01

    Full Text Available Biotemplating is the processing of microcellular ceramics by reproduction of natural morphologies, where the microstructural features of the biotemplate are maintained in the biomorphic ceramic. Different biotemplates with distinct pore anatomies were used to produce biomorphic supports for the zeolite coating: wood, cardboard, sea-sponge and sisal. The biomorphic ceramics were produced by distinguished processing routes: Al-gas infiltration-reaction, liquid-metal infiltration, dip-coating and sol-gel synthesis, in order to produce nitrides, carbides and oxides, depending on the processing conditions. The zeolite coating was performed by hydrothermal growth of MFI-type (Silicalite-1 and ZSM-5 zeolite crystals onto the internal pore walls of the biomorphic templates. The final biomorphic ceramic-zeolite composites were physically characterized, evaluated in terms of their gas adsorption capabilities and correlated to their microstructure and specific pore anatomy. The combination of the properties of the biomorphic ceramics with the adsorption properties of zeolites results in materials with distinct properties as potential candidates for adsorption and catalytic applications due to their characteristic porosity, molecular sieving capabilities and high thermo-mechanical strength.

  4. The effect of metal ion exchange and alkali metal doping on the electrical conductivity of the Faujasite-type zeolite 13X

    International Nuclear Information System (INIS)

    Swart, S.

    1983-12-01

    Zeolite 13X was synthesized in the sodium form. Some transition metal cations were introduced into the zeolite framework by ion exchange reactions. These different cationic zeolite forms were doped or impregnated with sodium metal, utilizing the adsorptive properties of the zeolite. An A.C. technique was used to determine the electrical conductivity of the dehydrated ion exchanged zeolites and the sodium impregnated zeolite samples as a function of temperature. The conductivity value obtained was used to determine some thermodynamic parameters relating to the conduction process. For the dehydrated ion exchanged zeolites the electrical conductivity showed a general decrease with a decreasing ion exchange capacity. The sodium impregnated zeolites showed an increase in conductivity with respect to the dehydrated unimpregnated samples. This was attributed to the presence of Na 6 5 + centres in the impregnated zeolites. The reduction of some of the metal cations by the sodium on impregnation did not appear to have any significant effect on the overall ionic conductivity of the samples. The conductivity as a function of temperature and pressure for the dehydrated sodium form of zeolite 13X and its impregnated counterpart was determined. The conductivity was found to increase with increasing pressure and temperature

  5. Adsorption of parent nitrosamine on the nanocrystaline M-ZSM-5 ...

    Indian Academy of Sciences (India)

    interactions were predicted from adsorption of nitrosamine on the M-zeolite clusters. The comparison of inter- ... 1. Introduction. Approximately 60–90% of human cancers are ... catalysts that have been widely used in the adsorption of serious ...

  6. Hidroxilación de fenol con catalizadores ZSM-5 modificado con cobre

    Directory of Open Access Journals (Sweden)

    César Augusto Caro

    2005-01-01

    Full Text Available Se sintetizaron varios catalizadores Cu-ZSM-5 con diferentes relaciones Si/Al y Si/Cu. Usando metilamina o hidróxido de sodio como agente mineralizante. Los catalizadores se caracterizaron por DRX, IR, análisis BET, UV-VIS y análisis elemental. El desempeño catalítico de los catalizadores sintetizados se evaluó en la hidroxilación de fenol con H2O2. Se encontró que la relación catecol (CAT/(hidroquinona (HQ + p-benzoquinona (PBQ aumentó con el contenido de agua, presentó un máximo cuando la relación en peso de agua/fenol fue de 53/1 y se favoreció a altas temperaturas, con el aumento del contenido de aluminio o con la disminución en el contenido de catalizador. El contenido de cobre no fue un factor determinante para la conversión ni para la selectividad en la hidroxilación de fenol. La producción de la p-benzoquinona (PBQ, producto de oxidación de la hidroquinona, fue mínimo cuando se usaron las siguientes condiciones: 80 ºC, fenol: 1 mmol, relación molar fenol/H2O2 de 3/1, catalizador: 20 mg, agua: 5 g, tiempo de reacción: 4 h.

  7. Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

    2017-11-15

    As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous

  8. Comparative study of the active sites in zeolites by different probe molecules

    Directory of Open Access Journals (Sweden)

    ALINE AUROUX

    2005-03-01

    Full Text Available This review summarizes some of the recently published results concerning the acid sites in the zeolites ZSM-5 and Y studied by temperature-programmed desorption (TPD and adsorption calorimetry using different probe molecules NH3, CO, N2O and n-hexane. For the first time it has been shown that the acid sites in hydrated zeolites are accessible for n-hexane adsorption

  9. Low-Temperature Pd/Zeolite Passive NO x Adsorbers: Structure, Performance, and Adsorption Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yang [Institute for Integrated; Kovarik, Libor [Institute for Integrated; Engelhard, Mark H. [Institute for Integrated; Wang, Yilin [Institute for Integrated; Wang, Yong [Institute for Integrated; Gao, Feng [Institute for Integrated; Szanyi, János [Institute for Integrated

    2017-07-14

    Pd/zeolite passive NOx adsorber (PNA) materials were prepared with solution ion-exchange between NH4/zeolites (Beta, ZSM-5 and SSZ-13) and PdCl2 solutions. The nature of Pd (dispersion, distribution and oxidation states) in these materials was characterized with Na+ ion-exchange, TEM imaging, CO titration with FTIR and in situ XPS. The NOx trapping and release properties were tested using feeds with different compositions. It is concluded that multiple Pd species coexist in these materials: atomically dispersed Pd in the cationic sites of zeolites, and PdO2 and PdO particles on the external surfaces. While Pd is largely atomically dispersed in ZSM-5, the small pore opening for SSZ-13 inhibits Pd diffusion such that the majority of Pd stays as external surface PdO2 clusters. NOx trapping and release are not simple chemisorption and desorption events, but involve rather complex chemical reactions. In the absence of CO in the feed, cationic Pd(II) sites with oxygen ligands and PdO2 clusters are reduced by NO to Pd(I) and PdO clusters. These reduced sites are the primary NO adsorption sites. In the presence of H2O, the as-formed NO2 desorb immediately. In the presence of CO in the feed, metallic Pd, “naked” Pd2+, and Pd+ sites are responsible for NO adsorption. For Pd adsorption sites with the same oxidation states but in different zeolite frameworks, NO binding energies are not expected to vary greatly. However, NO release temperatures do vary substantially with different zeolite structures. This indicates that NO transport within these materials play an important role in determining release temperatures. Finally, some rational design principles on efficient PNA materials are suggested. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a

  10. Leaching and antimicrobial properties of silver nanoparticles loaded onto natural zeolite clinoptilolite by ion exchange and wet impregnation

    CSIR Research Space (South Africa)

    Missengue, RNM

    2015-11-01

    Full Text Available This study aimed to compare the leaching and antimicrobial properties of silver that was loaded onto the natural zeolite clinoptilolite by ion exchange and wet impregnation. Silver ions were reduced using sodium borohydride (NaBH(sub4...

  11. Controlled growth of gold nanoparticles in zeolite L via ion-exchange reactions and thermal reduction processes

    KAUST Repository

    Zeng, Shangjing

    2014-09-01

    The growth of gold nanoparticles in zeolite can be controlled using ion-exchange reactions and thermal reduction processes. We produce a number of different sizes of the gold nanoparticles with the particle size increasing with increased temperature of the final heat treatment. © 2014 Elsevier B.V.

  12. On two alternative mechanisms of ethane activation over ZSM-5 zeolite modified by Zn2+ and Ga1+ cations

    NARCIS (Netherlands)

    Kazansky, V.B.; Subbotina, I.R.; Rane, N.J.; Santen, van R.A.; Hensen, E.J.M.

    2005-01-01

    The activation of ethane over zinc- and gallium-modified HZSM-5 dehydrogenation catalysts was studied by diffuse reflectance infrared spectroscopy. Hydrocarbon activation on HZSM-5 modified by bivalent Zn and univalent Ga cations proceeds via two distinctly different mechanisms. The stronger

  13. Ion exchange and dehydration experimental studies of clinoptilolite: Implications to zeolite dating

    International Nuclear Information System (INIS)

    WoldeGabriel, G.

    1995-02-01

    Variable effects were noted on the argon (Ar) and potassium (K) contents of clinoptilolite fractions used in ion-exchange and dehydration experiments. The K contents of clinoptilolite fractions were differently affected during cation exchange with Ca-, Cs-, K-, and Na-chloride solutions. Ar was generally less affected during these experiments, except for a Na-clinoptitolite fraction exchanged for five days. Loss of Ar during organic heavy-liquid treatment and cleaning using acetone and deionized water does occur, as indicated by comparing the amounts of radiogenic Ar of treated and untreated fractions. Moreover, a regular decrease in radiogenic Ar contents was noted in clinoptilolite fractions during dehydration experiments at different temperatures for 16 hours. Comparable losses do not occur from saturated samples that were heated in 100 C for more than five months. Water appears to play a vital role in stabilizing the clinoptilolite framework structure and in the retention of Ar. The radiogenic Ar depletion pattern noted in clinoptilolite fractions dehydrated in unsaturated environment at different temperatures is similar to variations in the amount of radiogenic Ar observed in clinoptilolite samples from the unsaturated zone of an altered tuff. These results can be used to evaluate the extent of zeolitic water (and hence Ar) retention in unsaturated geologic settings. The utility of alkali zeolites (e.g., phillipsite, clinoptilolite, and mordenite) from low-temperature, open-hydrologic alteration as potential dateable minerals was evaluated using the K/Ar method as part of the Yucca Mountain Site Characterization Project, which is evaluating Yucca Mountain, Nevada, as a potential high-level radioactive waste repository site

  14. The PILO process: zeolites and titanates in the treatment of spent ion exchange resins

    International Nuclear Information System (INIS)

    Hultgren, Aa.; Thegerstroem, C.; Forberg, S.; Westermark, T.; Faelt, L.

    1981-01-01

    Spent ion exchange resins from power reactor operation contain more than 95% of the total radioactivity of wet reactor wastes. Cementation and bituminization are the two methods applied in Sweden up to now for the immobilization of spent resins. Over the last years, however, research and development work has resulted in a proposed process (PILO), where > 99.9 % of cesium and strontium and around 90 % of other radioactive nuclides are eluted from the spent resins and sorbed in zeolites and titanates in a chromatographic process. The inorganic sorbents are dried after loading and sintered to yield long-term stable products, while the treated resins may be incinerated to give ash residues of fairly short-lived activity. The development work has included production, characterization and testing of different zeolites and titanates, bench-scale optimization of the chromatographic process using actual spent resins, heat treatment of the loaded inorganic sorbents, and resin incineration. Over-all system design studies including transport requirements, integrated process flowsheets, and cost estimates are now in progress. The aim is to have a sufficient basis during spring 1982 to decide on the merits of a PILO plant at the planned repository for low and medium level waste (SFR), to be commissioned in 1988. (Auth.)

  15. Elucidation of the mechanism of conversion of methanol and ethanol to hydrocarbons on a new type of synthetic zeolite

    NARCIS (Netherlands)

    Derouane, E.G.; Nagy, J.B.; Dejaifve, P.; Hooff, van J.H.C.; Spekman, B.P.A.; Védrine, J.C.; Naccache, C.

    1978-01-01

    13C nuclear magnetic resonance and vapor-phase chromatography have been used to investigate the conversions of methanol and ethanol to hydrocarbons on a synthetic zeolite of the type H-ZSM-5 as described by Mobil. Methanol is first dehydrated to dimethyl ether and ethylene. Then the reaction

  16. Does Density of Cationic Sites Affect Catalytic Activity of Co Zeolites in Selective Catalytic Reduction of NO with Methane?

    Czech Academy of Sciences Publication Activity Database

    Dědeček, Jiří; Kaucký, Dalibor; Wichterlová, Blanka

    2002-01-01

    Roč. 18, 3/4 (2002), s. 283-290 ISSN 1022-5528 R&D Projects: GA AV ČR IBS4040016 Institutional research plan: CEZ:AV0Z4040901 Keywords : Co zeolites * ZSM-5 * NO reduction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.648, year: 2002

  17. Catalytic Performance of Zeolite-Supported Vanadia in the Aerobic Oxidation of 5-hydroxymethylfurfural to 2,5- diformylfuran

    DEFF Research Database (Denmark)

    Sádaba, Irantzu; Gorbanev, Yury; Kegnæs, Søren

    2013-01-01

    on the four different zeolite supports H-beta, H-Y, H-mordenite, and H-ZSM-5 with 1–10 wt% vanadia loading were prepared and characterized by nitrogen physisorption, X-ray powder diffraction, scanning electron  microscopy, ammonia temperature-programmed desorption, Raman spectroscopy and UV...

  18. Characterization by Sem, EDS and micro-Raman of the influence of the molar ratio SiO2/Al2O3 and reduction temperature on the system CuZSM5

    International Nuclear Information System (INIS)

    Chavez R, F.; Rodriguez I, I.; Petranovskii, V.

    2014-01-01

    The morphological and spectroscopic changes caused by reduction of ion-exchanged CuZSM5 samples with SiO 2 /Al 2 O 3 molar ratios (MR) of 30 and 70 in H 2 flow at 150 and 350 grades C are discussed. the nominal copper loading was of 1% by weight. Scanning electron microscopy of CuZSM5 sample set showed that the treatment in reducing atmosphere at 350 grades C produces particle agglomeration and smoother surface texture that treatment at 150 grades C, this effect was more pronounced for the sample with MR 30. Furthermore, the particles corresponding to the sample with MR 30 are of irregular shape and have rough texture (cubic or rectangular crystals, protrusions) while the particles of the sample with MR 70 are in the majority of spherical smooth texture (leaf-shaped crystals/platelet, reclining). Energy Dispersive X-ray spectroscopy elemental analysis reveals a heterogeneous distribution of copper as well other elements in each sample. The micro-Raman spectroscopy shows some changes in the vibrational modes for the studied samples. (Author)

  19. The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil

    Directory of Open Access Journals (Sweden)

    Amalia Putri Purnamasari

    2017-10-01

    Full Text Available Transesterification of used cooking oil was carried out over calcium oxide supported on mesoporous H-ZSM-5 prepared from kaolin as solid base catalysts. Solid basic catalysts investigated in this study were characterized by XRD, FTIR spectroscopy, and N2 adsorption-desorption techniques. The XRD pattern showed peaks corresponding to the CaO and mesoporous ZSM-5 in the sample. The peak intensity of the CaO increased as CaO loading in ZSM-5 was increased. The characterization based on FTIR spectroscopy revealed that CaO/H-ZSM-5 solids have functional groups characteristics of both CaO and mesoporous H-ZSM-5 which appeared in the band at around  550 cm-1 and 480 cm-1. The isotherm of N2 adsorption-desorption of CaO/H-ZSM-5 indicated the type IV isotherm with the presence of hysteresis loop. For the catalytic activity, the biodiesel yield using catalyst of 10 % CaO/HZSM-5 (100 %, 30 % CaO/HZSM-5 (100 %, 50 % CaO/HZSM-5 (100 % were 24.34, 27.37, and 29.73 %, respectively. It also related with the basic active site, when loading CaO increased, the basic active site also increased. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 8th March 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Purnamasari, A.P., Sari, M.E.F., Kusumaningtyas, D.T., Suprapto, S., Hamid, A., Prasetyoko, D. (2017. The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 329-336 (doi:10.9767/bcrec.12.3.802.329-336

  20. Solution exchange corrosion testing with the glass-zeolite ceramic waste form in demineralized water at 900C

    International Nuclear Information System (INIS)

    Simpson, L. J.

    1998-01-01

    A ceramic waste form of glass-bonded zeolite is being developed for the long-term disposition of fission products and transuranic elements in wastes from the U.S. Department of Energy's spent nuclear fuel conditioning activities. Solution exchange corrosion tests were performed on the ceramic waste form and its potential base constituents of glass, zeolite 5A, and sodalite as part of an effort to qualify the ceramic waste form for acceptance into the Civilian Radioactive Waste Management System. Solution exchange tests were performed at 90 C by replacing 80 to 90% of the leachate with fresh demineralized water after set time intervals. The results from these tests provide information about corrosion mechanisms and the ability of the ceramic waste form and its constituent materials to retain waste components. The results from solution exchange tests indicate that radionuclides will be preferentially retained in the zeolites without the glass matrix and in the ceramic waste form, with respect to cations like Li, K, and Na. Release results have been compared for simulated waste from candidate ceramic waste forms with zeolite 5A and its constituent materials to determine the corrosion behavior of each component

  1. Substitution clustering in a non-stoichiometric celsian synthesized by the thermal transformation of barium exchanged zeolite X

    International Nuclear Information System (INIS)

    Clayden, Nigel J.; Esposito, Serena; Ferone, Claudio; Pansini, Michele

    2006-01-01

    The thermal transformation of Ba exchanged zeolite X to celsian has been studied by 27 Al and 29 Si MAS NMR spectroscopy. Evidence for the degradation of the zeolite framework is present in the 29 Si NMR spectra after thermal treatment at 850 deg. C. Confirmation is provided by the 29 Si NMR data that synthesis of celsian via the decomposition of Ba exchanged zeolite leads to a single defect phase. Clustering of the isomorphous replacement of aluminium by silicon must occur to explain the observed 29 Si chemical shifts. The 27 Al NMR data show distorted aluminium co-ordination sites upon the thermal transformation of Ba exchanged zeolite X. The distortions present in the amorphous matrix are greater than those present in the monoclinic and hexagonal crystalline phases of celsian. - Graphical abstract: Monte Carlo simulation of the Q 4 (mAl) silicon connectivity in the α-hexagonal celsian lattice, for a Si/Al ratio of 1:1. Si atoms are shown in yellow and the Al atoms in black

  2. Selective reduction of nitric oxide over Cu/ZSM-5: The role of oxygen in suppressing catalyst deactivation by carbonaceous deposits

    Energy Technology Data Exchange (ETDEWEB)

    d' Itri, Julie L; Sachtler, Wolfgang M.H. [V.N. Ipatieff Laboratory, Center for Catalysis and Surface Science, Departments of Chemical Engineering and Chemistry, Northwestern University, Evanston, IL (United States)

    1993-06-15

    The role of oxygen in the selective reduction of nitrogen monoxide by either propane or propene over 'excessively' ion-exchanged Cu/ZSM-5 has been studied. In a wide temperature region and in the absence of additives such as steam, propane is a more effective reductant than propene; with propane and in the presence of oxygen reduction of nitric oxide to nitrogen approaches 100% above 600 K. The difference in effectiveness is due to the different degree of catalyst deactivation by carbonaceous deposits: more carbonaceous material is deposited from propene than from propane. Temperature-programmed oxidation shows that above 600 K the rate of oxidation of carbonaceous deposits by oxygen is significant. The amount of such carbonaceous deposits is, therefore, lower when catalytic tests above 600 K are done in the presence of oxygen. At very high temperatures, the in situ volatilization of the deposits by reaction with oxygen keeps the catalyst surface clean in the steady state of nitric oxide reduction.

  3. Cryogenic adsorption of low-concentration hydrogen on charcoal, 5A molecular sieve, sodalite, ZSM-5 and Wessalith DAY

    International Nuclear Information System (INIS)

    Willms, R.S.

    1993-01-01

    The separation of low-concentration hydrogen isotopes from helium is a processing step that is required for ceramic lithium breeding blanket processing. Cryogenic adsorption is one method of effecting this separation. In this study live adsorbents were considered for this purpose: charcoal, 5A molecular sieve, UOP S-115, ZSM-5 and Wessalith DAY. The first two adsorbents exhibit good equilibrium loadings and are shown to be quite effective at adsorbing low-concentration hydrogen isotopes. The latter three adsorbents display considerably lower equilibrium loadings. This study concludes that by using either charcoal or 5A molecular sieve, cryogenic adsorption would be an effective means of separating hydrogen isotopes from helium

  4. Characterization by Sem, EDS and micro-Raman of the influence of the molar ratio SiO{sub 2}/Al{sub 2}O{sub 3} and reduction temperature on the system CuZSM5; Caracterizacion por SEM, EDS y micro-Raman de la influencia de la relacion molar SiO{sub 2}/Al{sub 2}O{sub 3} y temperatura de reduccion sobre el sistema CuZSM5

    Energy Technology Data Exchange (ETDEWEB)

    Chavez R, F. [Instituto Politecnico Nacional, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, 07738 Mexico D. F. (Mexico); Rodriguez I, I. [Universidad de la Habana, Instituto de Ciencia y Tecnologia de Materiales, Zapata y G. s/n, 10400 La Habana (Cuba); Petranovskii, V., E-mail: fchavez@esfm.ipn.mx [UNAM, Centro de Nanociencias y Nanotecnologia, Apdo. Postal 14, 22800 Ensenada, Baja California (Mexico)

    2014-07-01

    The morphological and spectroscopic changes caused by reduction of ion-exchanged CuZSM5 samples with SiO{sub 2}/Al{sub 2}O{sub 3} molar ratios (MR) of 30 and 70 in H{sub 2} flow at 150 and 350 grades C are discussed. the nominal copper loading was of 1% by weight. Scanning electron microscopy of CuZSM5 sample set showed that the treatment in reducing atmosphere at 350 grades C produces particle agglomeration and smoother surface texture that treatment at 150 grades C, this effect was more pronounced for the sample with MR 30. Furthermore, the particles corresponding to the sample with MR 30 are of irregular shape and have rough texture (cubic or rectangular crystals, protrusions) while the particles of the sample with MR 70 are in the majority of spherical smooth texture (leaf-shaped crystals/platelet, reclining). Energy Dispersive X-ray spectroscopy elemental analysis reveals a heterogeneous distribution of copper as well other elements in each sample. The micro-Raman spectroscopy shows some changes in the vibrational modes for the studied samples. (Author)

  5. Formation of hydroxyl groups and exchange with deuterium on NaHX and NaHY zeolites

    International Nuclear Information System (INIS)

    Kubelkova, L.; Novakova, J.

    1976-01-01

    Deammoniation and dehydroxylation of Na(NH 4 )X and Na(NH 4 )Y zeolites were compared. With the X type, both processes overlapped and proceeded more easily than with the Y type. Both H forms contained structural OH groups and hydroxyls denoted as SiOH, to which the 3740 cm -1 band in the IR spectrum was assigned. In addition, the NaHX zeolite contained OH groups characterized by the 3700 and 3600 cm -1 bands. Certain differences in the behaviour of NaHX and NaHY zeolites during deammoniation and dehydroxylation might be attributed to the presence of ''non-localizable'' H atoms. The active sites for the D 2 -OH exchange were probably formed during dehydroxylation. Hydrogen in SiOH groups was replaced by deuterium in both zeolite types more slowly than H atoms in other OH groups, which influenced the kinetic variations in the gaseous phase. The presence of water in the gaseous phase affected the kinetics and could distort the determination of the number of H atoms bound in the zeolites. (author)

  6. Relevance of the Mo-precursor state in H-ZSM-5 for methane dehydroaromatization

    KAUST Repository

    Vollmer, Ina

    2018-01-04

    Although the local geometry of Mo in Mo/HZSM-5 has been characterized before, we present a systematic way to manipulate the configuration of Mo and link it to its catalytic properties. The location and geometry of cationic Mo-complexes, the precursor of the active metal site for methane dehydroaromatization, are altered by directing the way they anchor to the framework of the zeolite. The feature used to direct the anchoring of Mo is the location of Al in the zeolite framework. According to DFT calculations, the local geometry of Mo should change, while UV-vis and pyridine FTIR spectroscopy indicated differences in the dispersion of Mo. Both aspects, however, did not influence the catalytic behavior of Mo/HZSM-5, indicating that as long as enough isolated Mo species are present inside the pores of the zeolite, the catalytic behavior is unaffected. This paves the way to better understand how the Mo oxo precursor transforms into the active phase under the reaction conditions.

  7. Relevance of the Mo-precursor state in H-ZSM-5 for methane dehydroaromatization

    KAUST Repository

    Vollmer, Ina; Li, Guanna; Yarulina, Irina; Kosinov, Nikolay; Hensen, Emiel J.; Houben, Klaartje; Mance, Deni; Baldus, Marc; Gascon, Jorge; Kapteijn, Freek

    2018-01-01

    Although the local geometry of Mo in Mo/HZSM-5 has been characterized before, we present a systematic way to manipulate the configuration of Mo and link it to its catalytic properties. The location and geometry of cationic Mo-complexes, the precursor of the active metal site for methane dehydroaromatization, are altered by directing the way they anchor to the framework of the zeolite. The feature used to direct the anchoring of Mo is the location of Al in the zeolite framework. According to DFT calculations, the local geometry of Mo should change, while UV-vis and pyridine FTIR spectroscopy indicated differences in the dispersion of Mo. Both aspects, however, did not influence the catalytic behavior of Mo/HZSM-5, indicating that as long as enough isolated Mo species are present inside the pores of the zeolite, the catalytic behavior is unaffected. This paves the way to better understand how the Mo oxo precursor transforms into the active phase under the reaction conditions.

  8. Waste crab shell derived CaO impregnated Na-ZSM-5 as a solid base catalyst for the transesterification of neem oil into biodiesel

    Directory of Open Access Journals (Sweden)

    Vijayalakshmi Shankar

    2017-11-01

    Full Text Available Activated calcium oxide extracted from crab shell impregnated on Na-ZSM-5 has been investigated. Crab shells were collected, powdered and calcined at 900 °C, and CaO was impregnated on Na-ZSM-5 and calcined at 550 °C for 10 h. The CaO/Na-ZSM-5 was characterized by X-ray diffraction, scanning electron microscopy and BET surface area. The prepared catalyst was tested for its catalytic activity by transesterifing neem oil into biodiesel in the presence of methanol. The influence of various parameters including reaction time, temperature, methanol to oil ratio, catalyst concentration and dosage were also investigated. Produced biodiesel have also been tested using proton NMR spectroscopy. Biodiesel yield as 95% has been achieved with 15% CaO impregnated on Na-ZSM-5 at 75 °C. The optimum transesterification reaction conditions were identified as follows: reaction temperature, 75 °C; reaction time, 6 h; methanol-to-neem oil molar ratio, 12:1; catalyst dosage, 0.2 g; and catalyst concentration, 15%. Based on the above study, it can be concluded that the calcium oxide impregnated Na-ZSM-5 can be a potential catalyst for biodiesel production.

  9. Hydrogen production by steam reforming of bio-oil aqueous fraction over Co-Fe/ZSM-5

    Science.gov (United States)

    Chen, Mingqiang; Wang, Yishuang; Liang, Tian; Yang, Zhonglian

    2018-02-01

    A series of Co-Fe/ZSM-5 catalysts were prepared by impregnation method and their catalytic performance under steam reforming bio-oil aqueous fraction (SRBAF). The as-prepared catalysts were characterized by XRD, BET, and SEM. The characterization results revealed the Co-Fe alloy phase was formed in Co0.5Fe0.5/ZSM-5 catalyst, and this catalyst exhibited unique pore volume (0.28 cm3/g) and pore size (8.4 nm). The results of experiment demonstrated the addition of Fe species could significantly increase C conversion and H2 yield, and the formation of Co-Fe alloy effectively inhibited methanation reaction and improved water-gas shift (WGS) reaction. The highest H2 yield (81%) and C conversion (85%) was obtained at the following reaction conditions: 2.5 g of C0.5F0.5/Z catalyst, T = 700 °C, S/C = 10-14,.feed flow rate was 10.0 gbio-oil/h, N2 flow rate was 0.16 L/min.

  10. The conversion of biomass to light olefins on Fe-modified ZSM-5 catalyst: Effect of pyrolysis parameters.

    Science.gov (United States)

    Zhang, Shihong; Yang, Mingfa; Shao, Jingai; Yang, Haiping; Zeng, Kuo; Chen, Yingquan; Luo, Jun; Agblevor, Foster A; Chen, Hanping

    2018-07-01

    Light olefins are the key building blocks for the petrochemical industry. In this study, the effects of in-situ and ex-situ process, temperature, Fe loading, catalyst to feed ratio and gas flow rate on the olefins carbon yield and selectivity were explored. The results showed that Fe-modified ZSM-5 catalyst increased the olefins yield significantly, and the ex-situ process was much better than in-situ. With the increasing of temperature, Fe-loading amount, catalyst to feed ratio, and gas flow rate, the carbon yields of light olefins were firstly increased and further decreased. The maximum carbon yield of light olefins (6.98% C-mol) was obtained at the pyrolysis temperature of 600°C, catalyst to feed ratio of 2, gas flow rate of 100ml/min, and 3wt% Fe/ZSM-5 for cellulose. The selectivity of C 2 H 4 was more than 60% for all feedstock, and the total light olefins followed the decreasing order of cellulose, corn stalk, hemicelluloses and lignin. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Salt-Zeolite Ion Exchange Equilibrium Studies for Complete Set of Fission Products in Molten LiCl-KCl

    International Nuclear Information System (INIS)

    Yoo, Tae-Sic; Frank, Steven M.; Simpson, Michael F.; Hahn, Paula A.; Battisti, Terry J.; Phongikaroon, Supathorn

    2010-01-01

    This paper presents results on LiCl-KCl based molten salts/zeolite-A contact experiments and the associated equilibrium ion exchange model. Experiments examine the contact behaviors of various ternary salts (LiCl-KCl-YCl3, LiCl-KCl-LaCl3, and LiCl-KCl-PrCl3) and quaternary salts (LiCl-KCl-CsCl-NdCl3 and LiCl-KCl-CsCl-SrCl2) with the zeolite-A. The developed equilibrium model assumes that there are ion exchange and occlusion sites, both of which are in equilibrium with the molten salt phase. A systematic approach in estimating total occlusion capacity of the zeolite-A is developed. The parameters of the model, including the total occlusion capacity of the zeolite-A, were determined from fitting experimental data collected via multiple independent studies including the ones reported in this paper. Experiments involving ternary salts were used for estimating the parameters of the model, while those involving quaternary salts were used to validate the model.

  12. Synthesis and characterization of mesoporous ZSM-5 core-shell particles for improved catalytic properties

    DEFF Research Database (Denmark)

    Kustova, Marina; Holm, Martin Spangsberg; Christensen, Claus H.

    2008-01-01

    samples were tested in the MTG reaction, and the results showed that both the shell-coated and the desilicated zeolites are significantly more resistant to coke formation. These results are ascribed to the effect of the removal of structural defects rather than to an improvement of the diffusion......HZSM-5 is a unique catalyst for the conversion of methanol, dimethyl ether and other oxygenates into gasoline. During this process, catalyst deactivation by coking requires frequent regeneration and the improvement of catalyst life time is one of the challenges in catalyst development...

  13. Adsorptive Desulfurization of Model Gasoline by Using Different Zn Sources Exchanged NaY Zeolites

    Directory of Open Access Journals (Sweden)

    Jingwei Rui

    2017-02-01

    Full Text Available A series of Zn-modified NaY zeolites were prepared by the liquid-phase ion-exchange method with different Zn sources, including Zn(NO32, Zn(Ac2 and ZnSO4. The samples were tested as adsorbents for removing an organic sulfur compound from a model gasoline fuel containing 1000 ppmw sulfur. Zn(Ac2-Y exhibited the best performance for the desulfurization of gasoline at ambient conditions. Combined with the adsorbents’ characterization results, the higher adsorption capacity of Zn(Ac2-Y is associated with a higher ion-exchange degree. Further, the results demonstrated that the addition of 5 wt % toluene or 1-hexene to the diluted thiophene (TP solution in cyclohexane caused a large decrease in the removal of TP from the model gasoline fuel. This provides evidence about the competition through the π-complexation between TP and toluene for adsorption on the active sites. The acid-catalyzed alkylation by 1-hexene of TP and the generated complex mixture of bulky alkylthiophenes would adsorb on the surface active sites of the adsorbent and block the pores. The regenerated Zn(Ac2-Y adsorbent afforded 84.42% and 66.10% of the initial adsorption capacity after the first two regeneration cycles.

  14. Study of isotopic exchange of radioactive calcium and cerium cations with y zeolites in aqueous and alcoholic solution

    Energy Technology Data Exchange (ETDEWEB)

    Guilloux, M

    1974-12-31

    Thesis. The isotopic exchange of y zeolite cations with calcium and cerium was studied. The experimental work was carried out utilizing the heterogeneous isotopic exchange between aqueous and alcoholic solutions of the cation considered and a zeolite powder containing a corresponding radioisotope. Aqueous phase exchanges demonstrate that a complex diffusion phenomenon is taking place which is capable of being decomposed into at least two distinct phases: a very slowly occurring phase representing 25 to 30% of the total exchange at ordinary temperatures and a very rapidly occurring phase. In alcoholic solutions, a rapid phase is always observed together with a slow diffusion phase although the exchange rates and diffusion coefficients may vary considerably with the nature and composition of the solvent. The results enable a hypothesis to be advanced on the ion exchange mechanism. The migration of the ions requires the crossing of two types of barrier: the large windows of the supercages (8A); the windows of the sodalite cages (2A). The two stages of the exchange kinetics can be related to these two types of barrier. (FR)

  15. Selective catalytic reduction of NO{sub x} to nitrogen over Co-Pt/ZSM-5: Part A. Characterization and kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Maisuls, S.E.; Seshan, K.; Feast, S.; Lercher, J.A. [Laboratory for Catalytic Processes and Materials, Faculty of Chemical Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2001-01-01

    The selective catalytic reduction of NO by propene in the presence of excess oxygen has been studied over catalysts based on Co-Pt supported on ZSM-5. Pure Pt based catalysts are highly active, but produce large amounts of N{sub 2}O. Bimetallic Co-Pt/ZSM-5 catalysts with low Pt contents (0.1wt.%) show a synergistic effect by combining high stability and activity of Pt catalysts with the high N{sub 2} selectivity of Co catalysts. The lower selectivity to N{sub 2}O is attributed to its selective conversion over Co. The catalysts also showed high water and sulfur tolerance above 350C.

  16. Capture and isotopic exchange method for water and hydrogen isotopes on zeolite catalysts up to technical scale for pre-study of processing highly tritiated water

    Energy Technology Data Exchange (ETDEWEB)

    Michling, R.; Braun, A.; Cristescu, I.; Dittrich, H.; Gramlich, N.; Lohr, N. [Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Glugla, M.; Shu, W.; Willms, S. [ITER Organization, Saint-Paul-lez-Durance (France)

    2015-03-15

    Highly tritiated water (HTW) may be generated at ITER by various processes and, due to the excessive radio toxicity, the self-radiolysis and the exceedingly corrosive property of HTW, a potential hazard is associated with its storage and process. Therefore, the capture and exchange method for HTW utilizing Molecular Sieve Beds (MSB) was investigated in view of adsorption capacity, isotopic exchange performance and process parameters. For the MSB, different types of zeolite were selected. All zeolite materials were additionally coated with platinum. The following work comprised the selection of the most efficient zeolite candidate based on detailed parametric studies during the H{sub 2}/D{sub 2}O laboratory scale exchange experiments (about 25 g zeolite per bed) at the Tritium Laboratory Karlsruhe (TLK). For the zeolite, characterization analytical techniques such as Infrared Spectroscopy, Thermogravimetry and online mass spectrometry were implemented. Followed by further investigation of the selected zeolite catalyst under full technical operation, a MSB (about 22 kg zeolite) was processed with hydrogen flow rates up to 60 mol*h{sup -1} and deuterated water loads up to 1.6 kg in view of later ITER processing of arising HTW. (authors)

  17. INVESTIGATION OF CLINOPTILOLITE NATURAL ZEOLITE REGENERATION BY AIR STRIPPING FOLLOWED BY ION EXCHANGE FOR REMOVAL OF AMMONIUM FROM AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    A. R. Rahmani ، M. T. Samadi ، H. R. Ehsani

    2009-07-01

    Full Text Available The purpose of this study was to regenerate clinoptilolite natural zeolite by air stripping followed by removal of ammonium from aqueous solutions. The research was carried out in continuous system. The characteristics of graded clinoptilolite from Semnan (one of the central provinces in Iran mines were determined and then regeneration tests were done by contacting of 1 N NaCl solution with given weights of ammonium saturated zeolite. Then the brine of column was transferred to the air stripping column for regeneration. The pH of brine solution before entrance to a stripping column was increased to 11. Air stripped ammonia from the brine was converted to the ammonium ion by using acid scrubber. The outlet effluent from stripping column was collected for reuse. The results showed that the cation exchange capacities were 17.31 to 18.38 mg NH4+/g of zeolite weight. Regeneration efficiency of zeolite by NaCl solution and air stripping was in the range of 92%-97% under various operational conditions. However, the efficiency of acid absorption of released ammonia in stripping process was 55% with a major rejection of the surplus ammonia to the atmosphere. It could be concluded that the method studied may be considered as an advanced and supplementary process for treating effluents of aqueous solution and fishponds in existing treatment plants.

  18. Redox properties of phenosafranine at zeolite-modified electrodes-Effect of surface modification and solution pH

    International Nuclear Information System (INIS)

    Easwaramoorthi, S.; Natarajan, P.

    2008-01-01

    Redox properties of cationic dye phenosafranine (3,7-diamino-5-phenylphenazenium chloride) (PS + ) were studied at zeolite-modified electrodes using Zeolite-Y and NaZSM-5. The peak current and peak potential of phenosafranine-adsorbed zeolite were found to be influenced by the pH of the electrolyte solution. Observation of a second redox couple is suggested to be due to formation of new species at low concentration from the reduced phenosafranine at the zeolite-modified electrodes. Titanium dioxide nanoparticles encapsulated in the cavities of the zeolite or anchored on the external surface of the zeolite do not seem to affect the redox properties of adsorbed PS + . When the cyclic voltammograms are recorded immediately after the electrode is immersed into the solution, the redox potential of PS + is found to be sensitive to the nature of the zeolite surface. The peak potential shifts towards positive region under continuous cycles as the surface hydroxyl groups get protonated in acidic electrolyte solution thereby forcing the movement of dye molecules from the zeolite surface to the zeolite electrode solution interface. The electron transfer rate constants for the adsorbed dye at the electrode are calculated to be 2.5 ± 0.2 s -1 and 3.5 ± 0.2 s -1 for the zeolite-Y electrode and the ZSM-5 electrode, respectively by the Laviron equation

  19. Fe-BEA Zeolite Catalysts for NH3-SCR of NOx

    DEFF Research Database (Denmark)

    Frey, Anne Mette; Mert, Selcuk; Due-Hansen, Johannes

    2009-01-01

    Iron-containing zeolites are known to be promising catalysts for the NH3-SCR reaction. Here, we will investigate the catalytic activity of iron-based BEA catalysts, which was found to exhibit improved activities compared to previously described iron-containing zeolite catalysts, such as ZSM-5...... and ZSM-12. Series of Fe-BEA zeolite catalysts were prepared using a range of different preparation methods. Furthermore, we found that an iron concentration around 3 wt% on BEA showed a small optimum in SCR activity compared to the other iron loadings studied....

  20. Ageing and structural effects on the sorption characteristics of Cd2+ by clinoptilolite and Y-type zeolite studied using isotope exchange technique

    International Nuclear Information System (INIS)

    Ahmed, I.A.M.; Young, S.D.; Crout, N.M.J.

    2010-01-01

    This research investigates the long-term kinetics of Cd 2+ sorption and desorption by calcium-exchanged clinoptilolite (CaCpt) and Y-type (CaY) zeolite using isotopic exchange with 109 Cd while maintaining pH at circumneutral values. The effects of Si/Al ratio and crystal structure of these zeolitic materials on intracrystalline transport of Cd are discussed. A first-order kinetic model was developed to describe the progressive transfer of Cd 2+ to a less reactive form within the zeolite structure, following initial sorption and subsequent desorption of Cd subject to different initial contact times. The kinetic model differentiates between two forms of sorbed Cd 2+ designated 'labile' and 'non-labile' in which the labile form is in immediate equilibrium with the free Cd 2+ ion activity in solution. A model combining diffusion and first-order kinetics for cation exchange was also employed to determine Cd 2+ diffusivity and intracrystalline exchange rates in CaY and CaCpt. The efficiency of Permeable Reactive Barriers (PRBs) containing zeolitic materials in protecting water systems against lateral flow of metal-contaminated leachate was simulated for three contrasting zeolites. The slow transfer of Cd between labile and non-labile forms was particularly important in moderating high concentration pulses of Cd traversing the PRB. In addition, the reversibility of Cd fixation effectively restored the sorption capability of the zeolite through slow leakage to drainage water.

  1. Bonding of Co Ions in ZSM-5, Ferrierite, and Mordenite: An X-ray Absorption, UV-Vis and IR Study

    Czech Academy of Sciences Publication Activity Database

    Drozdová, L.; Prins, R.; Dědeček, Jiří; Sobalík, Zdeněk; Wichterlová, Blanka

    2002-01-01

    Roč. 106, č. 9 (2002), s. 2240-2248 ISSN 1089-5647 R&D Projects: GA ČR GA104/00/0640 Institutional research plan: CEZ:AV0Z4040901 Keywords : ZSM-5 * Co(II)ions * Vis spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.611, year: 2002

  2. Coke formation during the methanol-to-olefin conversion: in situ microspectroscopy on individual H-ZSM-5 crystals with different Brønsted acidity

    NARCIS (Netherlands)

    Mores, D.; Kornatowski, J.; Olsbye, U.; Weckhuysen, B.M.

    2011-01-01

    Coke formation during the methanol-to-olefin (MTO) conversion has been studied at the single-particle level with in situ UV/Vis and confocal fluorescence microscopy. For this purpose, large H-ZSM-5 crystals differing in their Si/Al molar ratio have been investigated. During MTO, performed at 623 and

  3. A MAS NMR and DRIFT study of the Ga species in Ga/H-ZSM5 catalysts and their effect on propane ammoxidation

    NARCIS (Netherlands)

    Pal, P.; Quartararo, J.; Hamid, abd S.B.; Derouane, E.G.; Védrine, J.C.; Magusin, P.C.M.M.; Anderson, B.G.

    2005-01-01

    71Ga, 27Al and 29Si MAS-NMR and DRIFT spectroscopies were used to characterize the state of gallium in Ga/H-ZSM5 catalysts tested for their ability to catalyse the ammoxidation of propane. Ga-species were observed in two different possible environments: octahedrally-coordinated gallium in small

  4. CuY zeolite catalysts prepared by ultrasonication-assisted ion-exchange for oxidative carbonylation of methanol to dimethyl carbonate.

    Science.gov (United States)

    Woo, Je-Min; Seo, Jung Yoon; Kim, Hyunuk; Lee, Dong-Ho; Park, Young Cheol; Yi, Chang-Keun; Park, Yeong Seong; Moon, Jong-Ho

    2018-06-01

    The influence of ultrasonication treatment on the catalytic performance of CuY zeolite catalysts was investigated for the liquid-phase oxidative carbonylation of methanol to dimethyl carbonate (DMC). The deammoniation method of NH 4 Y into HY zeolites was optimized and characterized by elemental analyzer, derivative thermogravimetry, Brunauer-Emmett-Teller (BET) analyzer, and powder X-ray diffractometry, revealing that the HY zeolite deammoniated at 400 °C presented the highest surface area, complete ammonium/proton ion exchange, and no structure collapse, rendering it the best support from all the prepared zeolites. CuY zeolites were prepared via aqueous phase ion exchange with the aid of ultrasonication. Upon ultrasonication, the Cu + active centers were uniformly dispersed in the Y zeolites, penetrating the core of the zeolite particles in a very short time. In addition to enhancing the Cu dispersity, the ultrasonication treatment influenced the BET surface area, acid amount, Cu + /Cu 2+ ratio, and also had a relatively small impact on the Cu loading. Consequently, adequate exposure to ultrasonication was able to increase the conversion rate of methanol into dimethyl carbonate up to 11.4% with a comparable DMC selectivity of 23.7%. This methanol conversion is 2.65 times higher than that obtained without the ultrasonication treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. The porosity, adicity, and reactivity of dealuminated zeolite ZSM-5 at the single partical level: The influence of the zeolite architecture

    NARCIS (Netherlands)

    Aramburo, L.R.; Karwacki, L.; Cubillas, P.; Asahina, S.; de Winter, D.A.M.; Drury, M.R.; Buurmans, I.L.C.; Stavitski, I.; Mores, D.; Daturi, M.; Bazin, P.; Dumas, P.; Thibault-Starzyk, F.; Post, J.A.; Anderson, M.W.; Terasaki, O.; Weckhuysen, B.M.

    2011-01-01

    A combination of atomic force microscopy (AFM), high-resolution scanning electron microscopy (HR-SEM), focused-ion-beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), confocal fluorescence microscopy (CFM), and UV/Vis and synchrotronbased IR microspectroscopy was

  6. Enhanced 29Si spin-lattice relaxation and observation of three-dimensional lattice connectivity in zeolites by two-dimensional 29Si MASS NMR

    International Nuclear Information System (INIS)

    Sivadinarayana, C.; Choudhary, V.R.; Ganapathy, S.

    1994-01-01

    It is shown that considerable sensitivity enhancement is achieved in the 29 Si magic angle sample spinning (MASS) NMR spectra of highly siliceous zeolites by pre treating the material with oxygen. The presence of adsorbed molecular oxygen in zeolite channels promotes an efficient 29 Si spin-lattice relaxation via a paramagnetic interaction between the lattice 29 Si T-site and the adsorbed oxygen on zeolite channels. This affords an efficient 2-D data collection and leads to increased sensitivity. The utility of this method is demonstrated in a two-dimensional COSY-45 NMR experiment of a high silica zeolite ZSM-5. (author). 20 refs., 3 figs., 1 tab

  7. Methods for eluting radiocesium from zeolite ion exchange material in a column in the TMI-2 reactor containment building

    International Nuclear Information System (INIS)

    Knauer, J.B.; Campbell, D.O.; Collins, E.D.; King, L.J.

    1982-07-01

    Two alternative procedures were evaluated at Oak Ridge National Laboratory for potential use in eluting the radiocesium from Linde Ionsiv IE-95 zeolite in the pushcart ion exchange column in the TMI-2 containment building. The elution mechanism was iosotopic exchange of the radiocesium with stable cesium. Small zeolite ion exchange columns that had been loaded during ORNL tests of the Submerged Demineralizer System (SDS) flowsheet were eluted during these tests. One column was eluted using 0.25 M CsNO 3 , and a second column was eluted using 0.25 M CsH 2 BO 3 . Both eluent solutions were effective for removing the cesium. The 0.25 CsNO 3 eluent removed approx. 91% of the 137 Cs in 20 bed volumes and approx. 92% in 37.5 bed volumes. The 0.25 M CsH 2 BO 3 eluent removed approx. 82% of the 137 Cs in 20 bed volumes and approx. 85% in 40 bed volumes. In both cases, the radiation levels on the columns were reduced by a factor of approx. 30

  8. Ethylene formation by dehydration of ethanol over medium pore zeolites

    Science.gov (United States)

    Gołąbek, Kinga; Tarach, Karolina A.; Filek, Urszula; Góra-Marek, Kinga

    2018-03-01

    In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C3 + products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5 > TNU-9 > ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene.

  9. Effect of Co and Mo Loading by Impregnation and Ion Exchange Methods on Morphological Properties of Zeolite Y Catalyst

    Directory of Open Access Journals (Sweden)

    Didi Dwi Anggoro

    2016-03-01

    Received: 10th November 2015; Revised: 16th January 2016; Accepted: 16th January 2016 How to Cite: Anggoro, D.D., Hidayati, N., Buchori, L., Mundriyastutik, Y. (2016. Effect of Co and Mo Loading by Impregnation and Ion Exchange Methods on Morphological Properties of Zeolite Y Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 75-83. (doi:10.9767/bcrec.11.1.418.75-83 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.418.75-83

  10. Design and fabrication of zeolite macro- and micromembranes

    Science.gov (United States)

    Chau, Lik Hang Joseph

    2001-07-01

    The chemical nature of the support surface influences zeolite nucleation, crystal growth and elm adhesion. It had been demonstrated that chemical modification of support surface can significantly alter the zeolite film and has a good potential for large-scale applications for zeolite membrane production. The incorporation of titanium and vanadium metal ions into the structural framework of MFI zeolite imparts the material with catalytic properties. The effects of silica and metal (i.e., Ti and V) content, template concentration and temperature on the zeolite membrane growth and morphology were investigated. Single-gas permeation experiments were conducted for noble gases (He and Ar), inorganic gases (H2, N2, SF6) and hydrocarbons (methane, n-C4, i-C4) to determine the separation performance of these membranes. Using a new fabrication method based on microelectronic fabrication and zeolite thin film technologies, complex microchannel geometry and network (supported zeolite films. The zeolite micropatterns were stable even after repeated thermal cycling between 303 K and 873 K for prolonged periods of time. This work also demonstrates that zeolites (i.e., Sil-1, ZSM-5 and TS-1) can be employed as catalyst, membrane or structural materials in miniature chemical devices. Traditional semiconductor fabrication technology was employed in micromachining the device architecture. Four strategies for the manufacture of zeolite catalytic microreactors were discussed: zeolite powder coating, uniform zeolite film growth, localized zeolite growth, and etching of zeolite-silicon composite film growth inhibitors. Silicalite-1 was also prepared as free-standing membrane for zeolite membrane microseparators.

  11. STUDY OF EPOXIDE DECYCLISATION OF CARYOPHYLENE OXIDE WITH SYNTHETIC ZEOLITE AS CATALYSTS

    Directory of Open Access Journals (Sweden)

    Winarto Haryadi

    2010-06-01

    Full Text Available The reaction of epoxide ring opening of caryophillene oxide has been done using zeolite H-Y, H-sodalit, and H-ZSM-5 as catalysts. The reactions were done in two types, there were in dioxane solvent at temperature of 110 oC and without solvent at temperature of 175 oC. The catalyst weight was 10 % from caryophillene oxide weight, and the time of reaction was four hours. The product of reaction was analyzed using GC, FTIR, and GC-MS. The reactions of caryophillene oxide in dioxane solvent with the three kinds of zeolites did not give any targeted product. Whereas, the reactions without solvent gave three main products, there was one compound with one group of secondary hidroxyl (secondary alcohol, and two compounds of ketone from caryophillene. The reaction product of caryophillene oxide obtained without using solvent with the three type of catalysts were then compared. Conversion of three main products produced by H-ZSM-5 catalyst, H-sodalit catalyst and H-Y catalyst were 82.11 %, 54.92 % and 38.53 % respectively. For that reason, the transformation of caryophillene oxide using H-ZSM-5 catalyst was considered to be the best selective product. The alcohol product was resulted from reaction between caryophillene oxide and Bronsted acid, and  the ketone products was resulted from the reaction with Lewis acid in zeolite.   Keywords: Epoxide ring opening, HY, H-sodalit and HZSM-5

  12. Study of the thermal transformations of Co- and Fe-exchanged zeolites A and X by 'in situ' XRD under reducing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ronchetti, Silvia, E-mail: silvia.ronchetti@polito.it [Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Turcato, Elisa Aurelia; Delmastro, Alessandro [Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Esposito, Serena; Ferone, Claudio; Pansini, Michele [Laboratorio Materiali del Dipartimento di Meccanica, Strutture, Ambiente e Territorio, Facolta di Ingegneria dell' Universita di Cassino, Via G. Di Biasio 43, 03043 Cassino (Italy); Onida, Barbara; Mazza, Daniele [Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2010-06-15

    'In situ' high temperature X-ray diffraction under reducing atmosphere is used for the first time to study the thermal stability and transformations of Co- and Fe-exchanged A and X zeolites. TG-DTA and 'ex situ' XRD characterization were also carried out. The temperature of incipient crystallization of metallic phase was found to be 700 {sup o}C in Fe-zeolites and 800 {sup o}C in Co-zeolites. Moreover, ex situ X-ray experiments, after thermal treatment both under inert and reducing atmosphere, revealed the formation of ceramic phases upon the thermal collapse of the zeolitic framework. Metal nanoparticles were obtained by reduction and the size of metal clusters was found to range between 24 and 40 nm.

  13. Nano ZSM-5 type ferrisilicates as novel catalysts for ethylbenzene dehydrogenation in the presence of N 2O

    Science.gov (United States)

    Khatamian, M.; Khandar, A. A.; Haghighi, M.; Ghadiri, M.

    2011-11-01

    Nanosized ZSM-5 type ferrisilicates were successfully prepared using hydrothermal process. Several parameters including gel initiative compositions (Na+ or K+ alkali system), SiO2/Fe2O3 molar ratios and hydrothermal temperature were systematically investigated. The samples were characterized by XRD, TEM, SEM-EDS, BET surface area and ICP techniques. It was found that surface areas and the total pore volume increase with increasing in the SiO2/Fe2O3 molar ratio at Na-FZ ferrisilicates. The catalytic performance of the synthesized catalysts was evaluated in ethylbenzene dehydrogenation to styrene in the presence of N2O or steam at temperatures ranging from 400 °C to 660 °C under atmospheric pressure. The effects of gel initiative compositions, SiO2/Fe2O3 molar ratio as well as the hydrothermal synthesis temperature on the catalytic performance of these catalysts have been addressed. It was shown that styrene yield significantly influenced by altering in the SiO2/Fe2O3 ratio but was not greatly influenced by changes in hydrothermal synthesis temperatures. The comparison between performance of potassium and sodium containing catalysts was shown that the one with potassium has higher yield and selectivity toward styrene production at an optimum temperature of 610 °C.

  14. Catalytic Cracking of Triglyceride-Rich Biomass toward Lower Olefins over a Nano-ZSM-5/SBA-15 Analog Composite

    Directory of Open Access Journals (Sweden)

    Xuan Hoan Vu

    2015-10-01

    Full Text Available The catalytic cracking of triglyceride-rich biomass toward C2–C4 olefins was evaluated over a hierarchically textured nano-ZSM-5/SBA-15 analog composite (ZSC-24 under fluid catalytic cracking (FCC conditions. The experiments were performed on a fully automated Single-Receiver Short-Contact-Time Microactivity Test unit (SR-SCT-MAT, Grace Davison at 550 °C and different catalyst-to-oil mass ratios (0–1.2 g∙g−1. The ZSC-24 catalyst is very effective for transformation of triglycerides to valuable hydrocarbons, particularly lower olefins. The selectivity to C2–C4 olefins is remarkably high (>90% throughout the investigated catalyst-to-oil ratio range. The superior catalytic performance of the ZSC-24 catalyst can be attributed to the combination of its medium acid site amount and improved molecular transport provided by the bimodal pore system, which effectively suppresses the secondary reactions of primarily formed lower olefins.

  15. Mechanism of Framework Oxygen Exchange in Fe-Zeolites: A Combined DFT and Mass Spectrometry Study

    Czech Academy of Sciences Publication Activity Database

    Andrikopoulos, Prokopis C.; Sobalík, Zdeněk; Nováková, Jana; Sazama, Petr; Sklenák, Štěpán

    2013-01-01

    Roč. 14, č. 3 (2013), s. 520-531 ISSN 1439-4235 R&D Projects: GA AV ČR IAA400400812; GA ČR GA203/09/1627 Institutional support: RVO:61388955 Keywords : density functional theory * iron * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.360, year: 2013

  16. Aldol condensation of furfural with acetone over ion-exchanged and impregnated potassium BEA zeolites

    Czech Academy of Sciences Publication Activity Database

    Kikhtyanin, O.; Bulánek, R.; Frolich, K.; Čejka, Jiří; Kubička, D.

    2016-01-01

    Roč. 424, DEC 2016 (2016), s. 358-368 ISSN 1381-1169 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : activated hydrotalcites * carbon-monoxide * cyclic-ketones * Acetone * Furfural * Condensation * Potassium-BEA * Zeolite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.211, year: 2016

  17. Análise quantitativa das zeólitas ferrierita, ZSM-5 e mordenita presentes em amostras sintetizadas

    Directory of Open Access Journals (Sweden)

    B. J. B. Silva

    2015-03-01

    Full Text Available Nos estudos de obtenção de materiais zeolíticos é comum a formação de misturas de fases cristalinas devido à estabilidade relativa destes materiais no meio reacional empregado na síntese. Desta forma, é extremamente importante quantificar as diversas fases presentes no sistema para otimizar os métodos de sínteses de uma determinada zeólita sem a presença de contaminantes. Especificamente, foi verificado que durante a síntese das zeólitas ZSM-5(MFI, mordenita (MOR e ferrierita (FER, em diversas condições experimentais, ocorreram a formação de misturas de fases binárias (FER+MOR e (FER+MFI, às vezes ternárias (FER+MOR+MFI. O propósito do trabalho foi a realização de várias misturas binárias em diversos percentuais destes materiais, a fim de se obter uma metodologia para quantificar a presença de cada uma das fases (FER, MOR e MFI em amostras sintetizadas sob diferentes condições experimentais. Com este objetivo, foram preparadas misturas físicas com diversos teores das fases MFI, MOR e FER, a partir de amostras altamente cristalinas de cada fase. Estas fases de composições conhecidas foram analisadas por difração de raios X para quantificar as áreas dos picos característicos de cada material, podendo-se assim obter uma relação de percentual de fase/área de cada componente da mistura.

  18. A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO2/Ag-exchanged-zeolite-A nanocomposite

    Science.gov (United States)

    Nosrati, Rahimeh; Olad, Ali; Nofouzi, Katayoon

    2015-08-01

    The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO2/Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV-visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO2/Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO2/Ag-exchanged-zeolite-A nanocomposite additive with TiO2 to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination.

  19. Analysis of the Structural Parameters Controlling the Temperature Window of the Process of SCR-NOx by Low Paraffins over Metal-Exchanged Zeolites

    Czech Academy of Sciences Publication Activity Database

    Sobalík, Zdeněk; Vondrová, Alena; Tvarůžková, Zdenka; Wichterlová, Blanka

    2002-01-01

    Roč. 75, - (2002), s. 347-351 ISSN 0920-5861 R&D Projects: GA AV ČR IBS4040016; GA MŠk OC D15.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : catalytic activity * metal-exchanged zeolites * nitrogen oxides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.146, year: 2002

  20. Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

    Science.gov (United States)

    Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

    2011-01-01

    Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

  1. Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

    Directory of Open Access Journals (Sweden)

    Gunter Hagen

    2011-08-01

    Full Text Available Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers.

  2. Adsorption of Water and Ethanol in MFI-Type Zeolites

    KAUST Repository

    Zhang, Ke

    2012-06-12

    Water and ethanol vapor adsorption phenomena are investigated systematically on a series of MFI-type zeolites: silicalite-1 samples synthesized via both alkaline (OH -) and fluoride (F -) routes, and ZSM-5 samples with different Si/Al ratios as well as different charge-balancing cations. Full isotherms (0.05-0.95 activity) over the range 25-55 °C are presented, and the lowest total water uptake ever reported in the literature is shown for silicalite-1 made via a fluoride-mediated route wherein internal silanol defects are significantly reduced. At a water activity level of 0.95 (35 °C), the total water uptake by silicalite-1 (F -) was found to be 0.263 mmol/g, which was only 12.6%, 9.8%, and 3.3% of the capacity for silicalite-1 (OH -), H-ZSM-5 (Si/Al:140), and H-ZSM-5 (Si/Al:15), respectively, under the same conditions. While water adsorption shows distinct isotherms for different MFI-type zeolites due to the difference in the concentration, distribution, and types of hydrophilic sites, the ethanol adsorption isotherms present relatively comparable results because of the overall organophilic nature of the zeolite framework. Due to the dramatic differences in the sorption behavior with the different sorbate-sorbent pairs, different models are applied to correlate and analyze the sorption isotherms. An adsorption potential theory was used to fit the water adsorption isotherms on all MFI-type zeolite adsorbents studied. The Langmuir model and Sircar\\'s model are applied to describe ethanol adsorption on silicalite-1 and ZSM-5 samples, respectively. An ideal ethanol/water adsorption selectivity (α) was estimated for the fluoride-mediated silicalite-1. At 35 °C, α was estimated to be 36 for a 5 mol % ethanol solution in water increasing to 53 at an ethanol concentration of 1 mol %. The adsorption data demonstrate that silicalite-1 made via the fluoride-mediated route is a promising candidate for ethanol extraction from dilute ethanol-water solutions. © 2012

  3. A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO2/Ag-exchanged-zeolite-A nanocomposite

    International Nuclear Information System (INIS)

    Nosrati, Rahimeh; Olad, Ali; Nofouzi, Katayoon

    2015-01-01

    Graphical abstract: - Highlights: • A novel nanocomposite coating based on polyacrylic was prepared. • Nanostructured TiO 2 /Ag-exchanged-zeolite-A composite material was prepared. • Prepared nanocomposite used as additive for modification of polyacrylic latex. • Modified coatings show self-cleaning and antibacterial properties. • Modified coatings show better stability in water in versus of unmodified polymer. - Abstract: The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO 2 /Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV–visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO 2 /Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO 2 /Ag-exchanged-zeolite-A nanocomposite additive with TiO 2 to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination

  4. A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO{sub 2}/Ag-exchanged-zeolite-A nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Nosrati, Rahimeh, E-mail: ra.nosrati@gmail.com [Polymer Composite Research Laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Olad, Ali, E-mail: a.olad@yahoo.com [Polymer Composite Research Laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Nofouzi, Katayoon, E-mail: nofouzi@tabrizu.ac.ir [Faculty of Veterinary Medicine, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2015-08-15

    Graphical abstract: - Highlights: • A novel nanocomposite coating based on polyacrylic was prepared. • Nanostructured TiO{sub 2}/Ag-exchanged-zeolite-A composite material was prepared. • Prepared nanocomposite used as additive for modification of polyacrylic latex. • Modified coatings show self-cleaning and antibacterial properties. • Modified coatings show better stability in water in versus of unmodified polymer. - Abstract: The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO{sub 2}/Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV–visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO{sub 2}/Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO{sub 2}/Ag-exchanged-zeolite-A nanocomposite additive with TiO{sub 2} to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination.

  5. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    OpenAIRE

    E. Garrone; A. A. Tsyganenko; G. Turnes Palomino; C. Otero Areán

    2002-01-01

    Abstract: When adsorbed (at a low temperature) on alkali-metal-exchanged zeolites, CO forms both M(CO)+ and M(OC)+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO)+ t...

  6. Pyrolysis of polyethylene terephthalate containing real waste plastics using Ni loaded zeolite catalysts

    Science.gov (United States)

    Al-asadi, M.; Miskolczi, N.

    2018-05-01

    In this work the pyrolysis of polyethylene terephthalate (PET) containing real waste plastic was investigated using different Ni loaded catalysts: Ni/ZSM-5, Ni/y-zeolite, Ni/β-zeolite and Ni/natural zeolite (clinoptilolite). Raw materials were pyrolyzed in a horizontal tubular reactor between 600 and 900°C using 10% of catalysts. It was found, that both temperature increasing and catalysts presence can increase the gas yields, however owing to gasification reactions, the pyrolysis oil yield decreased with increasing temperature. Ni/y-zeolite catalyst had the most benefit in gas yield increasing at low temperature; however Ni/ZSM-5 showed advanced property in gas yield increasing at high temperature. Gases contained hydrogen, carbon oxides and hydrocarbons, which composition was significantly affected by catalysts. Ni loaded zeolites favoured to the formation of hydrogen and branched hydrocarbons; furthermore the concentrations of both CO and CO2 were also increased as function of elevated temperature. That phenomenon was attributed to the further decomposition of PET, especially to the side chain scission reactions. Owing to the Boudouard reaction, the ratio of CO2/CO can increased with temperature. Pyrolysis oils were the mixtures of n-saturated, n-unsaturated, branched, oxygen free aromatics and oxygenated hydrocarbons. Temperature increasing has a significant effect to the aromatization and isomerization reactions, while the catalysts can efficiently decreased the concentration of oxygen containing compounds.

  7. Radioisotope tracer study of co-reactions of methanol with ethanol using 11C-labelled methanol over alumina and H-ZSM-5

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Salmi, T.; Murzin, D.Yu

    2005-01-01

    Complete text of publication follows. The transformation of methanol has been investigated over alumina and H-ZSM-5 in our previous experiments by 11 C-radioisotope tracing. The main product in methanol conversion over alumina was dimethyl ether due to Lewis acid sites while over H-ZSM-5 mostly hydrocarbons were formed due to both Lewis and Brrnsted acid sites. With increasing temperature first the ethanol was dehydrated to diethyl ether followed by ethene formation over alumina and H-ZSM-5. In this work, 11 C-labelled methanol as radioisotope tracer was added to non-radioactive methanol for investigation of co-reaction with non-radioactive ethanol over alumina and H- ZSM-5. The 11 C-methanol tracer was used to distinguish the methanol derivates and co-reaction derivates of methanol with ethanol against non-radioactive ethanol derivates. The yield of methyl ethyl ether as mixed ether and the influence of ethanol for the yields of C 1 -C 5 hydrocarbons were studied as a function of reaction temperature and contact time. The 11 C-methanol was formed by a radiochemical process from 11 CO 2 produced at cyclotron. The mixture of methanol and ethanol was added to 11 C-methanol and injected to the catalyst. The catalysis was carried out in a glass tube fixed-bed reactor after its pretreatment. The derivates were analyzed by radio-gas chromatography (gas chromatograph with thermal conductivity detector coupled on-line with a radioactivity detector). The comparative analysis of yields of radioactive and non-radioactive products as a function of reaction temperature gives information about the reaction pathways. Over alumina the yields of dimethyl ether and methyl ethyl ether (co-product) as radioactive and diethyl ether with ethene as non-radioactive main products were monitored as a function of reaction temperature and reaction time in the range of 513-593 K. Alongside ethanol derivates the ethene turns into main product in contrast with methyl ethyl ether and diethyl

  8. Preparação do sistema Fe2O3/ZSM-5 para uso como catalisador na reação foto-Fenton

    Directory of Open Access Journals (Sweden)

    J. S. de Oliveira

    Full Text Available Resumo Este trabalho objetivou a preparação da zeólita ZSM-5 suportada com nanopartículas de óxido de ferro para uso como catalisador na degradação de um poluente orgânico em solução aquosa a partir do processo foto-Fenton. A zeólita foi preparada usando gel nucleante como indutor de formação da estrutura tipo MFI. Nanopartículas de óxido de ferro foram suportadas sobre a zeólita através da técnica de impregnação incipiente. Além disso, nanopartículas de óxido de ferro foram preparadas para fins de comparação entre as atividades catalíticas na reação foto-Fenton. Os materiais produzidos foram caracterizados por difração de raios X, microscopia eletrônica de varredura e análise de adsorção/dessorção de nitrogênio. Os resultados revelaram a formação do sistema Fe2O3/ZSM-5 com propriedades intrínsecas que resultaram em satisfatória atividade catalítica, sendo superior ao óxido de ferro. Além disso, esse sistema apresentou excelente atividade e estabilidade após três ciclos de reuso. O material Fe2O3/ZSM-5 produzido neste trabalho apresenta-se como um catalisador promissor para uso na reação foto-Fenton para a degradação de poluentes orgânicos em soluções aquosas.

  9. Catalytic reduction of NOx in gasoline engine exhaust over copper- and nickel-exchanged X-zeolite catalysts

    International Nuclear Information System (INIS)

    Bhattacharyya, S.; Das, R.K.

    2001-01-01

    Catalytic removal of NO x in engine exhaust gases can be accomplished by non-selective reduction, selective reduction and decomposition. Noble metals are extensively used for non-selective reduction of NO x and up to 90% of engine NO x emissions can be reduced in a stoichiometric exhaust. This requirement of having the stoichiometric fuel-air ratio acts against efficiency improvement of engines. Selective NO x reduction in the presence of different reductants such as, NH 3 , urea or hydrocarbons, requires close control of the amount of reductant being injected which otherwise may be emitted as a pollutant. Catalytic decomposition is the best option for NO x removal. Nevertheless, catalysts which are durable, economic and active for NO x reduction at normal engine exhaust temperature ranges are still being investigated. Three catalysts based on X-zeolite have been developed by exchanging the Na+ ion with copper, nickel and copper-nickel metal ions and applied to the exhaust of a stationary gasoline engine to explore their potential for catalytic reduction of NO x under a wide range of engine and exhaust conditions. Some encouraging results have been obtained. The catalyst Cu-X exhibits much better NO x reduction performance at any temperature in comparison to Cu-Ni-X and Ni-X; while Cu-Ni-X catalyst exhibits slightly better performance than Ni-X catalyst. Maximum NO x efficiency achieved with Cu-X catalyst is 59.2% at a space velocity (sv) of 31 000 h -1 ; while for Cu-Ni-X and Ni-X catalysts the equivalent numbers are 60.4% and 56% respectively at a sv of 22 000 h -1 . Unlike noble metals, the doped X-zeolite catalysts exhibit significant NO x reduction capability for a wide range of air/fuel ratio and with a slower rate of decline as well with increase in air/fuel ratio. (author)

  10. One-step preparation of zeolite silicalite-1 microspheres with adjustable macroporosity

    KAUST Repository

    Hua, Jia

    2009-06-23

    A facile one-step method was developed for the preparation of zeolite silicalite-1 (or ZSM-5) microspheres without the need of pre-synthesizing zeolite nanocrystals. In this method, Pluronic triblock copolymer F127 was added into a homogeneous silicalite-1 synthesis solution. During the hydrothermal synthesis, zeolite nanocrystals (∼ 100 nm) were formed and spontaneously assembled into uniform micrometer-sized (3-5 μm) spheres due to the presence of F127. The obtained microspheres possess significant textual porosity (up to 0.24 cm 3/g), which can be adjusted by simply adding different amounts of styrene in the synthesis. The zeolite microspheres are useful for enzyme immobilization, and the enzyme loading is proportional to the textual porosity. © 2009 American Chemical Society.

  11. Elastic behavior of MFI-type zeolites: 3 – Compressibility of silicalite and mutinaite

    International Nuclear Information System (INIS)

    Quartieri, Simona; Arletti, Rossella; Vezzalini, Giovanna; Di Renzo, Francesco; Dmitriev, Vladimir

    2012-01-01

    We report the results of an in-situ synchrotron X-ray powder diffraction study – performed using silicone oil as “non-penetrating” pressure transmitting medium – of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeled A and B) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P2 1 /n) to orthorhombic (Pnma) symmetry occurs at about 1.0 GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of the phase transition, are: K 0 =18.2(2) and K 0 =14.3 (2) GPa, respectively. These values makes silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition, at P amb and 0.9 GPa, respectively. The elastic behaviors of the three MFI-type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites – which are the phases with the highest Si/Al ratios and hence the lowest extraframework contents – show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and water molecules. - Graphical abstract: High-pressure behavior of silicalite compressed in silicone oil: projection of the structure along the [0 1 0] direction at Pamb(a), 0.9 GPa (b). (c) Comparison of the unit-cell volume variations as a function of pressure for mutinaite, H-ZSM5, Na-ZSM5, silicalite A, and silicalite B compressed in silicone oil. Highlights: ► X-ray powder diffraction study of silicalite and mutinaite

  12. Elastic behavior of MFI-type zeolites: 3 - Compressibility of silicalite and mutinaite

    Energy Technology Data Exchange (ETDEWEB)

    Quartieri, Simona, E-mail: squartieri@unime.it [Dipartimento di Scienze della Terra, Universita di Messina, Viale Ferdinando Stagno d' Alcontres 31, 98166 Messina S. Agata (Italy); Arletti, Rossella [Dipartimento di Scienze Mineralogiche e Petrologiche, Via Valperga Caluso 35, 10125 Torino (Italy); Vezzalini, Giovanna [Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia, Via S. Eufemia 19, 41100 Modena (Italy); Di Renzo, Francesco [Institut Charles Gerhardt de Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, 8 rue Ecole Normale, 34296 Montpellier (France); Dmitriev, Vladimir [Swiss-Norwegian Beam Line at ESRF, BP220, 38043 Grenoble Cedex (France)

    2012-07-15

    We report the results of an in-situ synchrotron X-ray powder diffraction study - performed using silicone oil as 'non-penetrating' pressure transmitting medium - of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeled A and B) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P2{sub 1}/n) to orthorhombic (Pnma) symmetry occurs at about 1.0 GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of the phase transition, are: K{sub 0}=18.2(2) and K{sub 0}=14.3 (2) GPa, respectively. These values makes silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition, at P{sub amb} and 0.9 GPa, respectively. The elastic behaviors of the three MFI-type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites - which are the phases with the highest Si/Al ratios and hence the lowest extraframework contents - show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and water molecules. - Graphical abstract: High-pressure behavior of silicalite compressed in silicone oil: projection of the structure along the [0 1 0] direction at Pamb(a), 0.9 GPa (b). (c) Comparison of the unit-cell volume variations as a function of pressure for mutinaite, H-ZSM5, Na-ZSM5, silicalite A, and silicalite B compressed in silicone oil. Highlights: Black-Right-Pointing-Pointer X-ray powder

  13. Performance test of silver ion-exchanged zeolite for the removal of gaseous radioactive methyl iodide at high temperature condition

    International Nuclear Information System (INIS)

    Byung-Seon Choi; Geun-Il Park; Jung-Won Lee; Ho-Yeon Yang; Seung-Kon Ryu

    2003-01-01

    Performance tests of silver ion-exchanged zeolite (AgX) adsorbent for the control of radioiodine gas generated from a high-temperature process were carried out using both non-radioactive and a radioactive methyl iodide tracers. From the identification of SEM-EDAX analysis, an experimental result of silver ion-exchanged ratio containing 10∼30 wt% of Ag was fit to that calculated by the weight increment, and it was confirmed that the silver was uniformly distributed inside the pores of the adsorbent. Demonstration test of AgX-10 adsorbent using radioactive methyl iodide tracer was performed. The removal efficiency of radioiodine with AgX-10 in the temperature ranges of 150 to 300 deg C was in the ranges of 99.9% to 99.99%, except for 300 deg C. The influence of the long-term weathering and the poisoning with NO 2 gas (200 ppm) on adsorption capacity of AgX-10 was also analyzed. The removal efficiency of radioactive methyl iodide by AgX-10 weathered for 14 weeks was 99.95%. Long-term poisoning test showed that the adsorption efficiency of methyl iodide started to decrease after 10 weeks, and the removal efficiency of radioiodine by AgX-10, poisoned for 16 weeks, was 99% (DF=100). (author)

  14. CALCULATION OF CATALYTIC REACTIVITY FOR PREPARING DICHLORODIMETHYLSILANE UTILIZING PRE- AND POST-MODIFIED 24T AlCl3/ZSM-5

    Directory of Open Access Journals (Sweden)

    Wenyuan Xu

    Full Text Available Dichlorodimethylsilane is the most important raw material for the preparation of organic silicon materials. Currently, the preparation of dichlorodimethylsilane is mainly based on disproportionation method. This method can turn wastes (by-products into treasures but the mechanism is still indeterminate. In this study, MP2/6-311++G (3df, 2pd basis set was used to study the mechanism of the disproportionation for producing dichlorodimethylsilane. Dichlorodimethylsilane is catalyzed by 24T cluster AlCl3/ZSM-5 catalyst and modified by (AlCl2+, and (BCl2+. The calculation results show that the rate-determining step is the reaction of the catalyst with trimethylchlorosilane . The activation energy of the rate-determining step of main reaction is: 393.83, 427.73, and 527.61 kJ mol-1, respectively. The structure analysis, activation energy analysis and LOL analysis for different catalysts all show that the catalytic effect of unmodified AlCl3/ZSM-5 is better.

  15. Upgrading of bio-oil derived from tobacco using ferrierite, ZSM-5 and Co-Mo/Al2 O3 catalysts

    Directory of Open Access Journals (Sweden)

    Sawitree Mulika

    2015-03-01

    Full Text Available This research aims to investigate bio-oil yield of tobacco leave by pyrolysis at 450-550o C. The bio-oil was upgraded by ferrierite, ZSM-5, Al2 O3 , Co-Mo/Al2 O3 and Mo2 C catalysts. Pyrolysis was carried out in a semi-batch reactor with a space velocity of 1.7 h-1 under nitrogen atmosphere. The highest liquid yield of 47.1% was observed at 500o C with the high heating value of 36.3 MJ/kg oil (organic phase. Furthermore, char and gas yields were 36.7 and 16.2%, respectively. As a result, the high heating values of the bio-oils catalyzed at 500o C by ferrierite, ZSM-5, Al2 O3 , Mo2 C and Co-Mo/Al2 O3 were 22.5, 24.7, 26.1, 35.8 and 36.8 MJ/kg oil (organic phase, respectively.

  16. Catalytic pyrolysis of woody biomass in a fluidized bed reactor: influence of the zeolite structure

    Energy Technology Data Exchange (ETDEWEB)

    A. Aho; N. Kumar; K. Eranen; T. Salmi; M. Hupa; D.Yu. Murzin [Aabo Akademi University, Aabo/Turku (Finland). Process Chemistry Centre, Laboratory of Industrial Chemistry and Reaction Engineering

    2008-09-15

    Catalytic pyrolysis of biomass from pine wood was carried out in a fluidized bed reactor at 450{sup o}C. Different structures of acidic zeolite catalysts were used as bed material in the reactor. Proton forms of Beta, Y, ZSM-5, and Mordenite were tested as catalysts in the pyrolysis of pine, while quartz sand was used as a reference material in the non-catalytic pyrolysis experiments. The yield of the pyrolysis product phases was only slightly influenced by the structures, at the same time the chemical composition of the bio-oil was dependent on the structure of acidic zeolite catalysts. Ketones and phenols were the dominating groups of compounds in the bio-oil. The formation of ketones was higher over ZSM-5 and the amount of acids and alcohols lower than over the other bed materials tested. Mordenite and quartz sand produced smaller quantities of polyaromatic hydrocarbons than the other materials tested. It was possible to successfully regenerate the spent zeolites without changing the structure of the zeolite. 12 refs., 9 figs., 5 tabs.

  17. An isotopic method to distinguish between ion exchange and adsorption of diazonium cations of zeolites

    International Nuclear Information System (INIS)

    Mohl, M.; Fejes, P.; Horvath, G.

    1984-01-01

    The ion exchange isotherms of two different diazonium cations have been determined on synthetic mordenite and faujasite using 22 Na as radiotracer. Under similar conditions (but with no radiotracer) the isotherms were followed spectrophotometrically so that a comparison between the amounts of ion exchanged and adsorbed cations can be made. (author)

  18. Nanocellulose-Zeolite Composite Films for Odor Elimination.

    Science.gov (United States)

    Keshavarzi, Neda; Mashayekhy Rad, Farshid; Mace, Amber; Ansari, Farhan; Akhtar, Farid; Nilsson, Ulrika; Berglund, Lars; Bergström, Lennart

    2015-07-08

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite-CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 μm thick zeolite-CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography-mass spectroscopy (GC/MS) analysis showed that the CNF-zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

  19. Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation

    KAUST Repository

    Imran, Ali

    2016-03-11

    Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liquid yield due to the increased production of non-condensables, primarily hydrocarbons. The catalytically produced bio-oil was less viscous and zeolites were effective at cracking heavy molecular weight compounds in the bio-oil. Acidic zeolites, H-Y and H-ZSM5, increased the desirable chemical compounds in the bio-oil such as phenols, furans and hydrocarbon, and reduced the undesired compounds such as acids. On the other hand reducing the acidity of zeolites reduced some of the undesired compounds in the bio-oil such as ketones and aldehydes. The performance of H-Y was superior to that of the rest of zeolites studied: bio-oil of high chemical and calorific value was produced with a high organic liquid yield and low oxygen content. H-ZSM5 was a close competitor to H-Y in performance but with a lower yield of bio-oil. Online fractionation of catalytic pyrolysis vapors was employed by controlling the condenser temperature and proved to be a successful process parameter to tailor the

  20. Aluminum siting in silicon-rich zeolite frameworks: A combined high-resolution Al-27 NMR spectroscopy and quantum mechanics/molecular mechanics study of ZSM-5

    Czech Academy of Sciences Publication Activity Database

    Sklenák, Štěpán; Dědeček, Jiří; Li, Chengbin; Wichterlová, Blanka; Gábová, Vendula; Sierka, M.; Sauer, J.

    2007-01-01

    Roč. 46, č. 38 (2007), s. 7286-7289 ISSN 1433-7851 R&D Projects: GA AV ČR 1ET400400413; GA ČR GA203/06/1449; GA AV ČR IAA4040308 Institutional research plan: CEZ:AV0Z40400503 Keywords : MQ MAS NMR * chemical-shifts * ab-initio * catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 10.031, year: 2007

  1. Lamellar and pillared ZSM-5 zeolites modified with MgO and ZnO for catalytic fast-pyrolysis of eucalyptus woodchips

    Czech Academy of Sciences Publication Activity Database

    Fermoso, J.; Hernando, H.; Jana, P.; Moreno, I.; Přech, Jan; Ochoa-Hernández, Cristina; Pizzaro, P.; Coronado, J. M.; Čejka, Jiří

    2016-01-01

    Roč. 277, č. 1 (2016), s. 171-181 ISSN 0920-5861 R&D Projects: GA ČR(CZ) GAP106/12/0189 EU Projects: European Commission(XE) 604307 - CASCATBEL Institutional support: RVO:61388955 Keywords : lignocellulosic biomass * catalytic fast-pyrolysis * bio-oil Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.636, year: 2016

  2. Síntese de zeólita tipo NaA a partir de caulim para obtenção de zeólita 5A através de troca iônica Synthesis of NaA zeolites from kaolin for obtaining 5A zeolites through ion exchange

    Directory of Open Access Journals (Sweden)

    C. R. Melo

    2010-12-01

    Full Text Available A síntese de zeólitas com o intuito de utilizá-las posteriormente como materiais adsorventes exige rigoroso controle das variáveis de processamento. Para cada tipo diferente de zeólita, existem variáveis de processo distintas para obtenção do tipo específico desejado. Neste trabalho os objetivos foram obter zeólita NaA partindo de caulim, para posteriormente obter zeólita 5A por meio de troca iônica com esta zeólita anteriormente sintetizada. Estas zeólitas, por sua vez, podem ser usadas como adsorventes altamente seletivos para adsorver, por exemplo, metais pesados de efluentes industriais. Os resultados obtidos foram satisfatórios, a metodologia utilizada mostrou-se eficiente. A partir do metacaulim comercial utilizado, obteve-se com sucesso zeólita tipo NaA, e por meio de trocas iônicas obteve-se zeólita 5A. A porcentagem de sódio trocada na zeólita final foi 61,4%.Zeolites synthesis as adsorbing materials requires accurate control of the variables. There are distinct process variables for obtaining specific desired types depending on each different kind of zeolite to be synthesized. This paper was aimed at obtaining NaA zeolites from kaolin in order to obtain zeolites A afterwards through ionic exchange with the previously synthesized zeolite. These zeolites can then be used as highly selective adsorbents to adsorb, for instance, heavy metals in industrial effluents. The results obtained were satisfactory, the methodology was efficient. From the commercial metakaolin used NaA zeolite was obtained successfully, and through ionic exchanges 5A zeolite was obtained. The exchangeable sodium percentage in the final zeolite was 61.4%.

  3. High-Performance Thin-Film-Nanocomposite Cation Exchange Membranes Containing Hydrophobic Zeolitic Imidazolate Framework for Monovalent Selectivity

    Directory of Open Access Journals (Sweden)

    Jian Li

    2018-05-01

    Full Text Available Zeolitic imidazolate framework-8 (ZIF-8 offers good hydrothermal, chemical, and thermal stabilities, and is therefore of interest in membrane synthesis. In this work, an interfacial polymerization (IP method was applied by anchoring ZIF-8 to the skin layer of thin-film nanocomposite (TFN membranes in order to obtain monovalent selectivity in electrodialysis. Organic trimesoyl chloride (TMC, 0.1 wt % solutions and aqueous m-phenyl diamine (MPD, 2% w/v solutions were used during the interfacial polymerization process. A range of polyamine (PA/ZIF-8 based membranes was fabricated by varying the concentration of ZIF-8 in the organic solution. The properties of the primary and modified membrane were characterized by scanning electron microscope (SEM, energy dispersive X-ray analysis (EDAX, atomic force microscopy (AFM, water uptake, ion exchange capacity, and contact angle measurements. No significant changes of the surface structure of the PA/ZIF-8 based membranes were observed. Nevertheless, the presence of ZIF-8 under the PA layer plays a key role in the separation process. For single salt solutions that were applied in electrodialysis (ED, faster transport of Na+ and Mg2+ was obtained after introducing the ZIF-8 nanoparticles, however, the desalination efficiency remained constant. When the hybrid membranes were applied to electrodialysis for binary mixtures containing Na+ as well as Mg2+, it was demonstrated that the monovalent selectivity and Na+ flux were enhanced by a higher ZIF-8 loading.

  4. A bioscaffolding strategy for hierarchical zeolites with a nanotube-trimodal network.

    Science.gov (United States)

    Li, Guannan; Huang, Haibo; Yu, Bowen; Wang, Yun; Tao, Jiawei; Wei, Yingxu; Li, Shougui; Liu, Zhongmin; Xu, Yan; Xu, Ruren

    2016-02-01

    Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

  5. Effect of diverse ions, column temperature and flow rate on the dynamic exchange-properties of cesium in various types of zeolites

    International Nuclear Information System (INIS)

    Mimura, Hitoshi; Kanno, Takuji; Kimura, Toshiya.

    1982-01-01

    The effect of various diverse ions in solution, column temperature and flow rate on the dynamic exchange-properties of Cs have been studied with various types of zeolites, i.e., synthetic mordenite, natural mordenite and clinoptilolite. The concentration of nitric acid considerably affects on the break-through properties of Cs; break-through capacity (B. T. Cap), total capacity (T. Cap) and column utilization (U) decrease with increasing acid concentration. The break-throgh data in the pH range (pH >= 1) are as follows; above 50 (meq./100 g zeolite) for B. T. Cap, 110 (meq./100 g zeolite) for T. Cap and 45 (%) for U, respectively. On the other hand, the concentration of formic acid (<= 2 M) and sodium ion (<= 0.1 M) give no critical change on the break-through properties, and T. Cap was found to be nearly constant. Break-through capacity and exchange rate increase with an increase in column temperature, while T. Cap remains constant. Thus, a similar profile was found in the curves of these properties as a function of temperature. Their inflection point gives the value of C/Co asymptotically equals 0.63. The decrease in flow rate (S. V) appears to give an increase in both B. T. Cap and U. (author)

  6. Effect Of Particle Size Of Zeolite On The Mass Transfer Coefficient Of Strontium In The Radioactive Waste Ion-Exchange Process

    International Nuclear Information System (INIS)

    Dewi-Susilowati; Suyitno

    1998-01-01

    This research is aimed for finding out the volumetric mass transfer coefficient of the zeolite particle, ks. The experiment has been conducted using an ion exchange column. The column diameter and length are 4.2 cm and 28 cm, respectively. The experiments have been conducted by flowing in the feed to the ion-exchange column containing zeolite with the varied particle diameters, I.e. 20, 40, 60, 80 and 100 mesh. The feed concentrations of Sr(NO 3 ) 2 , have been varied, I.e. 100, 250, 450, 550 and 650 ppm, and so have been the flow rates, I.e/ 35, 49, 70, 90 and 105 ml/minute. Samples of the effluents have been taken at certain series of time and subjected to analysis using an Atomic Absorption Spectrophotometer. The analytical data obtained have shown that the mass transfer coefficient of the zeolite particle is predominantly affected by the zeolite structure, in particular is effected by the number of AI atoms that hold the K ions. The analytical result from the above parameters has been presented in the forms of several groups of dimensionless number. The equations obtained are: (k L *dp)/D L 18.902(Re) 0 ,378 (dp/D) 0 ,6972(Co * ) 0 ,2667 with a mean error of 7.26%; k S 2240.268(dp/D) 1 .553; and each of them is valid in range of: Re: 0.182 - 0.856; dp/D: 0.004 - 0.022; Co * : 9.5408x10 - 5 - 6.2827x10 - 4

  7. Furfural to Furfuryl Alcohol: Computational Study of the Hydrogen Transfer on Lewis Acidic BEA Zeolites and Effects of Cation Exchange and Tetravalent Metal Substitution.

    Science.gov (United States)

    Prasertsab, Anittha; Maihom, Thana; Probst, Michael; Wattanakit, Chularat; Limtrakul, Jumras

    2018-06-04

    The hydrogen transfer of furfural to furfuryl alcohol with i-propanol as the hydrogen source over cation-exchanged Lewis acidic BEA zeolite has been investigated by means of density functional calculations. The reaction proceeds in three steps. First the O-H bond of i-propanol is broken to form a propoxide intermediate. After that, the furylmethoxy intermediate is formed via hydrogen transfer process, and finally furylmethoxy abstracts the proton to form the furfuryl alcohol product. The second step is rate-determining by requiring the highest activation energy (23.8 kcal/mol) if the reaction takes place on Li-Sn-BEA zeolite. We find that the catalytic activity of various cation-exchanged Sn-BEA zeolites is in the order Li-Sn-BEA > Na-Sn-BEA > K-Sn-BEA. The lower activation energy for Li-Sn-BEA compared to Na-Sn-BEA and K-Sn-BEA can be explained by the larger charge transfer from the carbonyl bond to the catalyst, leading to its activation and to the attraction of the hydrogen being transferred. The larger charge transfer in turn is due to the smaller gap between the energies of furfural HOMO and the zeolite LUMO in Li-Sn-BEA, compared to both Na-Sn-BEA and K-Sn-BEA. In a similar way, we also compare the catalytic activity of tetravalent metal centers (Sn, Zr, and Hf) substituted into BEA and find in the order Zr ≥ Hf > Sn, based on activation energies. Finally we investigate statistically which property of the reactants is a suitable descriptor for an approximative prediction of the reaction rate in order to be able to quickly screen promising catalytic materials for this reaction.

  8. On the impact of olefins and aromatics in the methanol-to-hydrocarbon conversion over H-ZSM-5 catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.; Mueller, S.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. of Chemistry

    2012-07-01

    Methanol-to-hydrocarbons processes using HZSM-5 archetype acidic zeolites or zeotype SAPO-34 catalysts are regarded as a vital suite of conversion technologies to bypass petroleum-based routes for the production of specific fuels and petrochemical commodities. Special significance of the methanol chemistry originates from its versatility enabling selective transformations towards various products. Industry demonstrated successfully implementations of Methanol-To-Gasoline, Methanol-To-Olefin, and Methanol-To-Propylene processes, although the typical single-pass selectivity remained limited and recycling is necessary. Considerable fundamental research efforts both from experimental and computational sides contributed to unravel the underlying complex reaction mechanism. The indirect hydrocarbon pool mechanism, in which Broensted acid sites combined with adsorbed light olefins or lower methylbenzenes act as active centers, is generally accepted to explain the formation of light olefins. As olefin and aromatics populated catalytic sites show different reactivity in terms of activity and selectivity to ethylene or propylene, one could envision optimizing the product distribution by suitable co-feeding of specific hydrocarbons. The present work addresses three questions with an experimental study conducted under realistic MTP operation conditions: (1) How are ethylene and propylene formed at molecular level? (2) Which reaction pathway leads to the formation of undesired hydrogen transfer products? (3) Does olefin or aromatics co-feeding change the selectivity to ethylene or propylene? Xylenes and various olefins were co-fed with methanol to achieve a detailed understanding of the reaction mechanism over acidic HZSM-5 zeolites. Results suggest, that an olefin homologation/cracking route (olefin cycle) accounts for the autocatalytic (-like) nature and the majority of methanol consumption rather than the route involving aromatic intermediates (aromatics cycle). Co

  9. Effect of high-temperature treatment on Fe/ZSM-5 prepared by chemical vapor deposition of FeCl3. II. Nitrous oxide decomposition, selective oxidation of benzene to phenol, and selective reduction of nitric oxide by isobutane

    NARCIS (Netherlands)

    Zhu, Q.; Teeffelen, van R.M.; Santen, van R.A.; Hensen, E.J.M.

    2004-01-01

    The catalytic performance (nitrous oxide decomposition, hydroxylation of benzene to phenol with nitrous oxide, and selective reduction of nitric oxide by i-butane) was evaluated for a set of HZSM-5 and sublimed Fe/ZSM-5 catalysts, which have been extensively characterized in an earlier contribution

  10. Single-crystal Structure of Cd2+-exchanged Zeolite Y (FAU, Si/Al = 1.56), |Cd27.5(Cd8O4)2.5|[Si117Al75O384]-FAU

    International Nuclear Information System (INIS)

    Seo, Sung Man; Lim, Woo Taik

    2012-01-01

    The cations are quite mobile and may usually be exchanged by other cations. Ion exchange is the most important method for the modification of the physical and chemical properties of zeolites for use as catalysts, sorbents, and molecular sieves. The results of ion exchange into zeolites from aqueous solution are usually not simple. Often only a fraction of the original cations can be replaced, and attempts to overcome this may reveal a relatively sharp upper limit to exchange. When acetate salt of metal cations dissolves in water for exchange solution, metal hydroxide ions occurred. It can be exchanged for Na + ions into zeolite framework, leading to over exchange. The catalytic activity of Cd 2+ -exchanged zeolite Y for the formation of acetonitrile was studied for comparison with activated alumina (Al 2 O 3 ) and also examined for the formation of acetonitrile from ethane and ammonia. Its catalytic activity had much higher than that of Al 2 O 3 . It was found to be essentially inactive for the formation of acetonitrile from ethylamine

  11. Separation of cesium and strontium with zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Kanno, T; Hashimoto, H [Tohoku Univ., Sendai (Japan). Research Inst. of Mineral Dressing and Metallurgy

    1976-06-01

    The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it.

  12. Separation of cesium and strontium with zeolites

    International Nuclear Information System (INIS)

    Kanno, Takuji; Hashimoto, Hiroyuki

    1976-01-01

    The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it. (auth.)

  13. A novel zeolite process for clean end use of hydrocarbon products

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, K M [Neste Oy, Porvoo (Finland). Technology Centre

    1997-12-31

    In recent years zeolites such as ZSM-5 have attracted considerable interest for the catalysis of a wide range of hydrocarbon transformations. A novel process developed by Neste converts light olefins to higher molecular weight hydrocarbon products. A wide range of high quality diesel, solvents and lube oils can be produced by the new NESKO process. Hydrotreated products have excellent properties; negligible sulphur or nitrogen compounds, very low aromatic content and pour point lower than -50 deg C. Proprietary technology is used in this olefin oligomerization process. (author) (7 refs.)

  14. A novel zeolite process for clean end use of hydrocarbon products

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, K.M. [Neste Oy, Porvoo (Finland). Technology Centre

    1996-12-31

    In recent years zeolites such as ZSM-5 have attracted considerable interest for the catalysis of a wide range of hydrocarbon transformations. A novel process developed by Neste converts light olefins to higher molecular weight hydrocarbon products. A wide range of high quality diesel, solvents and lube oils can be produced by the new NESKO process. Hydrotreated products have excellent properties; negligible sulphur or nitrogen compounds, very low aromatic content and pour point lower than -50 deg C. Proprietary technology is used in this olefin oligomerization process. (author) (7 refs.)

  15. Selective transformation of syngas into gasoline-range hydrocarbons over mesoporous H-ZSM-5-supported cobalt nanoparticles.

    Science.gov (United States)

    Cheng, Kang; Zhang, Lei; Kang, Jincan; Peng, Xiaobo; Zhang, Qinghong; Wang, Ye

    2015-01-26

    Bifunctional Fischer-Tropsch (FT) catalysts that couple uniform-sized Co nanoparticles for CO hydrogenation and mesoporous zeolites for hydrocracking/isomerization reactions were found to be promising for the direct production of gasoline-range (C5-11 ) hydrocarbons from syngas. The Brønsted acidity results in hydrocracking/isomerization of the heavier hydrocarbons formed on Co nanoparticles, while the mesoporosity contributes to suppressing the formation of lighter (C1-4 ) hydrocarbons. The selectivity for C5-11 hydrocarbons could reach about 70 % with a ratio of isoparaffins to n-paraffins of approximately 2.3 over this catalyst, and the former is markedly higher than the maximum value (ca. 45 %) expected from the Anderson-Schulz-Flory distribution. By using n-hexadecane as a model compound, it was clarified that both the acidity and mesoporosity play key roles in controlling the hydrocracking reactions and thus contribute to the improved product selectivity in FT synthesis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Adsorption behaviors of thiophene, benzene, and cyclohexene on FAU zeolites: Comparison of CeY obtained by liquid-, and solid-state ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yucai [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Province, Liaoning Shihua University, Fushun 113001, Liaoning (China); Mo, Zhousheng; Yu, Wenguang; Dong, Shiwei; Duan, Linhai [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Gao, Xionghou, E-mail: gaoxionghou@petrochina.com.cn [Petrochemical Research Institute, PetroChina Company Limited, 9 Dongzhimen North Street, Dongcheng District, Beijing 100007 (China); Song, Lijuan, E-mail: lsong56@263.net [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Province, Liaoning Shihua University, Fushun 113001, Liaoning (China)

    2014-02-15

    Cerium containing Y zeolites were prepared by liquid- (L-CeY) and solid- (S-CeY) state ion exchange from NaY and HY, respectively. The structural and textural properties were characterized by XRD and N{sub 2} adsorption, and acidity properties were characterized by NH{sub 3} temperature-programmed desorption (NH{sub 3}-TPD) and in situ FTIR spectrum of chemisorbed pyridine (in situ Py-FTIR). Furthermore, the single component adsorption and multi-component competitive adsorption behavior of thiophene, benzene and cyclohexene on those zeolites have also been studied by using vapor adsorption isotherms, solution adsorption breakthrough curves, thermogravimetry and derivative thermogravimetry (TG/DTG), frequency response (FR) and in situ FTIR techniques. The results indicate that the primary adsorption mode of benzene is simply micropore filling process, but the nature of effect of aromatics on selective adsorption of thiophene is competitive adsorption. The strong chemical adsorptions and protonization reactions of thiophene and cyclohexene occur upon the Brönsted acid sites of the HY and L-CeY zeolites, and the preferable acid catalytic protonization reactions of olefins hinder the further adsorption of sulfur compounds.

  17. Review of the thermal stability and cation exchange properties of the zeolite minerals clinoptilolite, mordenite, and analcime; applications to radioactive waste isolation in silicic tuff

    International Nuclear Information System (INIS)

    Smyth, J.R.; Caporuscio, F.A.

    1981-06-01

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 85 0 C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks

  18. Study on Modification of NaX Zeolites: The Cobalt (II-Exchange Kinetics and Surface Property Changes under Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Hoai-Lam Tran

    2016-01-01

    Full Text Available The cobalt (II ion-exchange process followed the Freundlich and Langmuir adsorption models as well as the pseudo-second-order kinetic model. The cobalt-exchanged contents increased when the initial Co(NO32 solution concentration increased up to 0.14 mol L−1 at the optimal pH of 6.05. The N2 adsorption isotherms are mixed types I/II isotherms and H3 type hysteresis. Both the micropore and mesopore adsorptions occurred during the adsorption process. The modification, which is both the cobalt (II exchange and thermal treatment, significantly improved the surface properties of NaX zeolites. Accordingly, the optimal temperature range is 500 to 600°C for a thermal treatment. This is consistent with the results of XRD analysis.

  19. Investigation of zeolites by solid state quadrapole NMR

    International Nuclear Information System (INIS)

    Janssen, R.

    1990-01-01

    The subject of this thesis is the NMR investigation of zeolites. The nature and properties of zeolites are discussed. Some of the basic priniples of NMR techniques on quadrupole nuclei are presented. A special technique, namely a two-dimensional nutation experiment is discussed in detail. The theory of the nutation experiment for quadrupole spin species with spin quantum number 3/2 as well as 5/2 is presented. For both spin spcies the theoretical spectra are compared with experimental results. It is also shown that the nutation expeirment can be performed with several pulse schemes. It is shown how phase-sensitive pure-absorption nutation spectra can be obtained and an NMR-probe is presented that is capable of performing NMR experiments at high (up to 500 degree C) temperatures. The two-dimensional nutation NMR technique has been applied to sodium cations in zeolite NaA. For this purpose a numbre of zeolite samples were prepared that contained different amounts of water. With the aid of nutation NMR the hydration of the zeolite can be studied and conclusions can be drawn about the symmetry of the surrounding of the sodium cations. With the aid of an extension of the nutation NMR experiment: Rotary Echo Nutation NMR, it is shown that in zeolite NaA, in various stages of hydration, the sodium cations or water molecules are mobile. Proof is given by means of high-temperature 23 Na-NMR that dehydrates zeolite NaA undergoes a phase transition at ca. 120 degree C. In a high-temperature NMR investigation of zeolite ZSM-5 it is shown that the sodium ions start to execute motions when the temperature is increased. (author). 198 refs.; 72 figs.; 6 tabs

  20. The Potential of Fe-exchanged Y Zeolite as a Heterogeneous Fenton-type Catalyst for Oxidative Degradation of Reactive Dye in Water

    OpenAIRE

    Aleksić, M.; Koprivanac, N.; Lončarić Božić, A.; Kušić, H.

    2010-01-01

    The study aimed to investigate the potential of Fe-exchanged zeolites of Y-type as a catalyst in heterogeneous Fenton-type processes for the degradation of model organic pollutant, reactive azo dye C.I. Reactive Blue 137, in water. The research work was directed to investigate the influence of process variables, such as FeY catalyst dosage, Fenton reagent ratio, and initial operating pH on the efficiency of the treatment process. The performance of the studied heterogeneous process was compar...

  1. Catalytic oxidation of butyl acetate over silver-loaded zeolites

    International Nuclear Information System (INIS)

    Wong, Cheng Teng; Abdullah, Ahmad Zuhairi; Bhatia, Subhash

    2008-01-01

    The performance of silver-loaded zeolite (HY and HZSM-5) catalysts in the oxidation of butyl acetate as a model volatile organic compound (VOC) was studied. The objective was to find a catalyst with superior activity, selectivity towards deep oxidation product and stability. The catalyst activity was measured under excess oxygen condition in a packed bed reactor operated at gas hourly space velocity (GHSV) = 15,000-32,000 h -1 , reaction temperature between 150 and 500 deg. C and butyl acetate inlet concentration of 1000-4000 ppm. Both AgY and AgZSM-5 catalysts exhibited high activity in the oxidation of butyl acetate. Despite lower silver content, AgY showed better activity, attributed to better metal dispersion, surface characteristics and acidity, and its pore system. Total conversion of butyl acetate was achieved at above 400 deg. C. The oxidation of butyl acetate followed a simple power law model. The reaction orders, n and m were evaluated under differential mode by varying the VOC partial pressure between 0.004 and 0.018 atm and partial pressure of oxygen between 0.05 and 0.20 atm. The reaction rate was independent of oxygen concentration and single order with respect to VOC concentration. The activation energies were 19.78 kJ/mol for AgY and 32.26 kJ/mol for AgZSM-5, respectively

  2. Zeolite studies. Aluminium phosphate zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Haegh, G.S.; Blindheim, U.

    1983-12-01

    Alpo-zeolites (ALPO4-zeolites) have been synthesized by hydrothermal synthesis in an autoclave from alumina, tetralkylammonium hydroxide and phosphorus acid. Catalysis tests with hydrocarbons indicate that the compounds have good olefinisomerization activity and selectivity.

  3. Carbon dioxide adsorption over zeolite-like metal organic frameworks (ZMOFs) having a sod topology: Structure and ion-exchange effect

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.; Kim, J.; Yang, D.A.; Ahn, W.S. [Inha University, Inchon (Republic of Korea). Dept. of Chemical Engineering

    2011-04-15

    Zeolite-like metal organic framework (ZMOF) materials having rho and sod topologies were experimentally investigated as CO{sub 2} adsorbents for the first time. As-prepared ZMOF materials showed reasonably high CO{sub 2} adsorption capacities (ca. 51 and 53 mg/g(adsorbent) for rho- and sod-ZMOF, respectively) and high CO{sub 2}/N{sub 2} selectivity (> 20) at 298 K and 1 bar. The latter showed a higher heat of adsorption (27-45 kJ/mol). These ZMOFs exhibited better CO{sub 2} adsorption than ZIF-8, a commonly investigated zeolitic imidazolate framework (ZIF) material having the same sod topology but in a neutral framework. Partially ion-exchanged sod-ZMOFs by alkali-metals resulted in improved CO{sub 2} adsorption performance compared with the as-prepared ZMOF. The highest CO{sub 2} adsorption was obtained with K{sup +}-exchanged sod-ZMOF (61 mg/g(adsorbent)), representing a ca. 15% increase in adsorption capacity. Complete desorption of CO{sub 2} in the K{sup +}-sod-ZMOF was attained at mild conditions (40{sup o}C, He purging), and reversible and sustainable CO{sub 2} adsorption performance was demonstrated in 5 sets of recycling runs.

  4. Experimental investigation of attrition resistance of zeolite catalysts in two particle gas-solid-solid fluidization system

    International Nuclear Information System (INIS)

    Nawaz, Z.; Ziaoping, T.; Shu, Q.; Wei, F.; Naveed, S.

    2010-01-01

    In the study of mechanical degradation of 34 ZSM-5 and SAPO catalysts, using the gas jet attrition - ASTM standard fluidized bed test (D-5757), the effect of particle size and its quantitative analysis in co-fluidization environment was investigated on the air jet index (AJI) basis. In gas-solid-solid fluidized bed reactors (GSS-FBR), two different sized particles were fluidized under isothermal conditions. In case of ZSM-5 and SAPO-34, significant attrition resistance was observed, which was attributed to small pore size and specific structural strength of the mobile framework image (MFI) and chabasite (CHA) structures, respectively. The optimum AJI for SAPO-34 and ZSM-5 (of particle size 0.2 mm) in GSS-fluidization system was observed to be 0.0118 and 0.0062, respectively. In co-fluidization, deviations from Gwyn relationship were observed due to change in impact of collision. Therefore, zeolites are recommended as suitable catalysts or catalytic supports (for doping of expensive metals) and for commercial use in GSS-FBR. (author)

  5. Experimental Determination of the Molar Absorption Coefficient of n-Hexane Adsorbed on High-Silica Zeolites.

    Science.gov (United States)

    Gatti, Giorgio; Olivas Olivera, Diana F; Sacchetto, Vittoria; Cossi, Maurizio; Braschi, Ilaria; Marchese, Leonardo; Bisio, Chiara

    2017-09-06

    Determination of the molar absorption coefficients of the CH 3 bending mode at ν˜ =1380 cm -1 (ϵ 1380 ) of n-hexane adsorbed from the gas phase on two different dealuminated zeolites is derived by a combination of IR spectroscopy and microgravimetric analysis. High-silica zeolite Y (HSZ-Y) and zeolite ZSM-5 (with SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively) with different textural and surface features are selected to evaluate the effect of the pore structure and architecture on the value of ϵ 1380 of the adsorbed n-hexane. Experimental data indicate that the molecule experiences a different adsorption environment inside zeolites; thus resulting in a significant change of the dipole moment and very different ϵ 1380 values: (0.278±0.018) cm μmol -1 for HSZ-Y and (0.491±0.032) cm μmol -1 for ZSM-5. Experimental data are also supported by computational modeling, which confirms the effect of different matrices on the IR absorption intensity. This study reveals that the use of probe molecules for quantitative measurements of surface sites has to be judiciously adopted, especially if adsorption occurs in the restricted spaces of microporous materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. ESTUDIO SOBRE LA INFLUENCIA DE LA INCORPORACIÓN DE CATIÓN METÁLICO EN LA ACTIVIDAD CATALÍTICA Y COMPORTAMIENTO MAGNÉTICO DE ZEOLITAS ZSM-5

    Directory of Open Access Journals (Sweden)

    Clara Saux

    2011-01-01

    Full Text Available Se sintetizaron zeolitas ZSM-5 con relación molar Si/Al 17 por el método hidrotérmico, las que fueron modificadas con cobalto y cromo por la técnica de impregnación por vía húmeda en un 3 % p/p del metal. Los resultados obtenidos por DRX, indican que la incorporación de ambos metales de transición no altera la estructura, ni la cristalinidad de la matriz original. Se detecta la presencia de especies Co3O4 para Co-ZSM-5 y Cr2O3 para el caso de Cr-ZSM-5. De las medidas de magnetización a temperatura ambiente se observa el efecto de los metales de transición sobre el comportamiento netamente diamagnético de la matriz zeolítica con la aparición de ciclos de histéresis que no saturan por presentar una componente paramagnética. Ambos materiales fueron probados como catalizadores para la reacción de oxidación selectiva de estireno con peróxido de hidrógeno, presentando buenos resultados en actividad con una elevada selectividad (superior al 70 % hacia benzaldehído.

  7. Recent advances of pore system construction in zeolite-catalyzed chemical industry processes.

    Science.gov (United States)

    Shi, Jing; Wang, Yangdong; Yang, Weimin; Tang, Yi; Xie, Zaiku

    2015-12-21

    The kaleidoscopic applications of zeolite catalysts (zeo-catalysts) in petrochemical processes has been considered as one of the major accomplishments in recent decades. About twenty types of zeolite have been industrially applied so far, and their versatile porous architectures have contributed their most essential features to affect the catalytic efficiency. This review depicts the evolution of pore models in zeolite catalysts accompanied by the increase in industrial and environmental demands. The indispensable roles of modulating pore models are outlined for zeo-catalysts for the enhancement of their catalytic performances in various industrial processes. The zeolites and related industrial processes discussed range from the uni-modal micropore system of zeolite Y (12-ring micropore, 12-R) in fluid catalytic cracking (FCC), zeolite ZSM-5 (10-R) in xylene isomerization and SAPO-34 (8-R) in olefin production to the multi-modal micropore system of MCM-22 (10-R and 12-R pocket) in aromatic alkylation and the hierarchical pores in FCC and catalytic cracking of C4 olefins. The rational construction of pore models, especially hierarchical features, is highlighted with a careful classification from an industrial perspective accompanied by a detailed analysis of the theoretical mechanisms.

  8. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    Directory of Open Access Journals (Sweden)

    E. Garrone

    2002-07-01

    Full Text Available Abstract: When adsorbed (at a low temperature on alkali-metal-exchanged zeolites, CO forms both M(CO+ and M(OC+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO+ than for M(OC+ carbonyls, although the corresponding difference decreases substantially when going from Li+ to Cs+. By means of variable-temperature FTIR spectroscopy, this energy difference was determined for several alkali-metal cations, and the existence of a thermal equilibrium between M(CO+ and M(OC+ species was established. The current state of research in this field is reviewed here, with a view to gain more insight into the thermal isomerization process.

  9. Thermodynamics of reversible gas adsorption on alkali-metal exchanged zeolites - the interplay of infrared spectroscopy and theoretical calculations

    Czech Academy of Sciences Publication Activity Database

    Otero Areán, C.; Nachtigallová, Dana; Nachtigall, Petr; Garrone, E.; Rodríguez Delgado, M.

    2007-01-01

    Roč. 9, č. 12 (2007), s. 1421-1437 ISSN 1463-9076 R&D Projects: GA MŠk LC512; GA ČR GA203/06/0324 Grant - others:UIB(ES) MAT2006-05350 Institutional research plan: CEZ:AV0Z40550506 Keywords : adsorption * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.343, year: 2007

  10. Direct electron crystallographic determination of zeolite zonal structures

    International Nuclear Information System (INIS)

    Dorset, Douglas L.; Gilmore, Christopher J.; Jorda, Jose Luis; Nicolopoulos, Stavros

    2007-01-01

    The prospect for improving the success of ab initio zeolite structure investigations with electron diffraction data is evaluated. First of all, the quality of intensities obtained by precession electron diffraction at small hollow cone illumination angles is evaluated for seven representative materials: ITQ-1, ITQ-7, ITQ-29, ZSM-5, ZSM-10, mordenite, and MCM-68. It is clear that, for most examples, an appreciable fraction of a secondary scattering perturbation is removed by precession at small angles. In one case, ZSM-10, it can also be argued that precession diffraction produces a dramatically improved 'kinematical' data set. There seems to no real support for application of a Lorentz correction to these data and there is no reason to expect for any of these samples that a two-beam dynamical scattering relationship between structure factor amplitude and observed intensity should be valid. Removal of secondary scattering by the precession mode appears to facilitate ab initio structure analysis. Most zeolite structures investigated could be solved by maximum entropy and likelihood phasing via error-correcting codes when precession data were used. Examples include the projected structure of mordenite that could not be determined from selected area data alone. One anomaly is the case of ZSM-5, where the best structure determination in projection is made from selected area diffraction data. In a control study, the zonal structure of SSZ-48 could be determined from selected area diffraction data by either maximum entropy and likelihood or traditional direct methods. While the maximum entropy and likelihood approach enjoys some advantages over traditional direct methods (non-dependence on predicted phase invariant sums), some effort must be made to improve the figures of merit used to identify potential structure solutions

  11. The roles of ozone and zeolite on reactive dye degradation in electrical discharge reactors.

    Science.gov (United States)

    Peternel, L; Kusic, H; Koprivanac, N; Locke, B R

    2006-05-01

    In this study high voltage pulsed corona electrical discharge advanced oxidation processes (AOPs) were applied to bleach and degrade C.I. Reactive Green 8 and C.I. Reactive Red 45 organic dyes in water solutions. Two types of hybrid gas/liquid high voltage electrical discharge (corona) reactors, known as hybrid series and hybrid parallel were studied. The difference between these reactors relates to electrode configuration, which affects the amounts of ozone, hydrogen peroxide and hydroxyl radicals produced. Experiments were conducted using dye concentrations of 20 mgl(-1) and 75 mgl(-1), with and without NH4ZSM5 zeolite addition in order to determine possible effects of added solid particles to total process efficiency. The role of ozone in combination with zeolites was assessed through comparative direct ozonation experiments with ozone supplied by an ozone generator. UV/VIS spectrophotometric measurements and measurements of total organic carbon (TOC) were used for the determination of decolorization and mineralization rates.

  12. Long-living positron and positronium states in zeolites and microcrystalline oxides

    International Nuclear Information System (INIS)

    Kajcsos, Zs.; Liszkay, L.; Varga, L.; Lohonyai, L.; Lazar, K.

    1995-01-01

    Positron annihilation (PA) investigation were performed on zeolites (X, Y and ZSM-5) and on microcrystalline MgO, Al 2 O 3 and SiO 2 , providing long lifetime components attributed to o-Ps atoms. In addition to the positron lifetime (LT) measurements, the energy distribution (ED) of the annihilation gamma radiation spectrum was recorded in the 30 keV - 1.5 MeV range for different samples and was compared to reference distributions for Si and GaAs samples, where no long-living Ps states are formed. Apart from the strong correlation with the water content in the samples, the positron data collected testify much more pronounced positronium hosting features for powders of the mentioned oxides than for zeolites. Positron LT spectroscopy combined with recording of the ED of the annihilation radiation provides reliable information on the forming of long living 3γ states. (author) 15 refs.; 4 figs

  13. Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

    International Nuclear Information System (INIS)

    Motojima, K.; Kawamura, F.

    1984-01-01

    Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time

  14. Adsorption site of ammonia on copper-exchanged Y-type zeolite under coexisting water vapor. Temperature-programed desorption and infrared adsorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kasaoka, S.; Sasaoka, E.; Shiraga, T.; Ono, Y.

    1978-03-01

    Sodium Y zeolites were copper-exchanged with cupric nitrate in water, in aqueous ammonia, and in aqueous ammonia/ammonium chloride, and calcined at 500/sup 0/C. Temperature-programed desorption and IR spectroscopy showed three types of adsorption sites for 0.1-1.0% ammonia gas from nitrogen containing 0-12% water vapor: physisorption, adsorption as tetraamminocopper(II) on copper(II) sites (type 2 site), and adsorption as ammonium ion on hydroxyl sites (type 3 site). Adsorption on type 2 sites occurred only at high ammonia concentration; desorption occurred around 175/sup 0/C. Type 3 sites consisted of Cu(OH)/sup +/ and Al(OH)/sup +/, adsorbed ammonia from low concentrations, and at temperatures above 200/sup 0/C, were probably the active sites for the reduction of nitric oxide by ammonia.

  15. Influence of zeolite pore structure on product selectivities for protolysis and hydride transfer reactions in the cracking of n-pentane.

    Science.gov (United States)

    Miyaji, Akimitsu; Iwase, Yasuyoshi; Nishitoba, Toshiki; Long, Nguyen Quang; Motokura, Ken; Baba, Toshihide

    2015-02-21

    The conversion of n-pentane was carried out to examine the effects of reaction conditions on changes in product selectivities at 823 K, using zeolites with 10- and 12-membered rings. We also investigated the influence of the pore structure of these zeolites on their catalytic activities for both protolysis and hydride transfer reactions. In the first half of this work, we examined the influence of acidic proton concentration and n-pentane pressure on the reaction rates for protolysis and hydride transfer reactions using ZSM-5 zeolites. The rates of hydride transfer reactions were more influenced by pentane pressure compared to protolysis reactions, and were proportional to the square of n-pentane pressure and the concentration of acidic protons. In the second half of this work, the influence of the zeolite pore structure on changes in product selectivities with n-pentane conversion and that on the rates of protolysis and the hydride transfer reactions were revealed using various zeolites with 10- and 12-membered rings. The catalytic activities of zeolites for the protolysis and hydride transfer reactions were influenced more by the spatial volume of the zeolite cavity than the acid strength of protons on the zeolite.

  16. The use of Zeolite into the controlling of Lithium concentration in the PWR primary water coolant (I) : the influences of Ca, Mg and Boric Acid concentration into the exchanges capacity of Ammonium Zeolite

    International Nuclear Information System (INIS)

    Sumijanto; Siti-Amini

    1996-01-01

    In this first part of research, the influences of calsium, magnesium and boric acid concentrations to the zeolite uptake of lithium in the PWR primary water coolant have been studied. The ammonium form of zeolite was found by modification of the natural zeolite which was originated from Bayah. The results showed that the boric acid concentration in the normal condition of PWR operation absolutely did not affects the lithium uptake. The Li uptake efficiency was influenced by the presence of Ca and Mg ions in order to the presence of cations competition which was dominated by Ca ion

  17. Zeolites in poultry and swine production

    Directory of Open Access Journals (Sweden)

    Aline Félix Schneider

    Full Text Available ABSTRACT: Zeolites are minerals that have intriguing properties such as water absorption, ion adsorption and cation exchange capacity. There are approximately 80 species of natural zeolites recognized and hundreds of artificial zeolites, which have been researched in several fields. Due to their chemical characteristics, zeolites have great potential for use in animal production, especially in poultry and swine farms, as food additives, litter amendment and treatment of residues, with direct and indirect effects on performance, yield and quality of carcass, ambience of farm sheds and reduction of environmental pollution.

  18. Zeolite function studied by neutron diffraction

    International Nuclear Information System (INIS)

    Newsam, J.M.

    1988-01-01

    Some recent figures relating to industrial uses of zeolites are summarized. Recent advances in the application of neutron diffraction to zeolite science are overviewed, with particular emphasis on powder diffraction (PND) results. Single crystal neutron diffraction studies of some 17 hydrated natural and synthetic zeolites have now appeared and they provide a consistent picture of zeolite-water interactions. Complete PND studies of hydrated synthetic ABW- and SOD-framework zeolites have also been reported. Other PND studies have explored the structural consequences of non-framework cation exchange, of framework modification by dealumination, and of framework cation substitution. Relatively simple zeolite-hydrocarbon sorbate complexes that have been studied include benzene in zeolite Y, and benzene and pyridine in zeolite L. Areas that are well poised for further development include further extensions to lower symmetry systems, the use of PND data for zeolite structure solution, studies at elevated temperatures and pressures, and further studies of zeolite sorbate complexes. (author) 68 refs., 7 figs

  19. Biochemical evolution. I. Polymerization on internal, organophilic silica surfaces of dealuminated zeolites and feldspars

    Science.gov (United States)

    Smith, Joseph V.

    1998-01-01

    Catalysis at mineral surfaces might generate replicating biopolymers from simple chemicals supplied by meteorites, volcanic gases, and photochemical gas reactions. Many ideas are implausible in detail because the proposed mineral surfaces strongly prefer water and other ionic species to organic ones. The molecular sieve silicalite (Union Carbide; = Al-free Mobil ZSM-5 zeolite) has a three-dimensional, 10-ring channel system whose electrically neutral Si-O surface strongly adsorbs organic species over water. Three -O-Si tetrahedral bonds lie in the surface, and the fourth Si-O points inwards. In contrast, the outward Si-OH of simple quartz and feldspar crystals generates their ionic organophobicity. The ZSM-5-type zeolite mutinaite occurs in Antarctica with boggsite and tschernichite (Al-analog of Mobil Beta). Archean mutinaite might have become de-aluminated toward silicalite during hot/cold/wet/dry cycles. Catalytic activity of silicalite increases linearly with Al-OH substitution for Si, and Al atoms tend to avoid each other. Adjacent organophilic and catalytic Al-OH regions in nanometer channels might have scavenged organic species for catalytic assembly into specific polymers protected from prompt photochemical destruction. Polymer migration along weathered silicic surfaces of micrometer-wide channels of feldspars might have led to assembly of replicating catalytic biomolecules and perhaps primitive cellular organisms. Silica-rich volcanic glasses should have been abundant on the early Earth, ready for crystallization into zeolites and feldspars, as in present continental basins. Abundant chert from weakly metamorphosed Archaean rocks might retain microscopic clues to the proposed mineral adsorbent/catalysts. Other framework silicas are possible, including ones with laevo/dextro one-dimensional channels. Organic molecules, transition-metal ions, and P occur inside modern feldspars. PMID:9520372

  20. Evaluation of LTA-, FAU- and MFI-type zeolites as sorbents of some toxic components of tobacco smoke

    International Nuclear Information System (INIS)

    Iucolano, F.; Caputo, D.; Monetta, T.; Bellucci, F.; Colella, C.

    2008-01-01

    Zeolites 3A, 4A, 13X, H-ZSM-5 were investigated in order to evaluate their possible use in removing toxic compounds from cigarette smoke. Ammonia and acetaldehyde were selected as representative of a wide range of possible sorbates. Adsorption equilibrium data at 313K were collected and analyzed by Langmuir and virial equations to estimate the relevant values of Henry's constant, a useful parameter to estimate the affinity sorbents-sorbates at low pressure. Unlike the Langmuir model, the virial equation provided a good fit for both ammonia and acetaldehyde equilibrium data for all sorbents in the whole range of pressures, especially at low pressure. As already assessed for nitrosamines, FAU- and MFI-type zeolites showed the highest affinity for ammonia and acetaldehyde, allowing these sorbents to be considered an effective potential resource for the removal of some of the main pollutants of tobacco smoke.

  1. Solvent-Free Biginelli Reactions Catalyzed by Hierarchical Zeolite Utilizing a Ball Mill Technique: A Green Sustainable Process

    Directory of Open Access Journals (Sweden)

    Ameen Shahid

    2017-03-01

    Full Text Available A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing of solvent was applied. The hierachical zeolite catalyst (MFI27_6 showed high yield (86%–96% of DHPMs in a very short time (10–30 min. The recyclability of the catalyst for the subsequent reactions was examined in four subsequent runs. The catalyst was shown to be robust without a detectable reduction in catalytic activity, and high yields of products showed the efficient protocol of the Biginelli reactions.

  2. Biotemplating of Luffa cylindrica sponges to self-supporting hierarchical zeolite macrostructures for bio-inspired structured catalytic reactors

    International Nuclear Information System (INIS)

    Zampieri, Alessandro; Mabande, Godwin T.P.; Selvam, Thangaraj; Schwieger, Wilhelm; Rudolph, Alexander; Hermann, Ralph; Sieber, Heino; Greil, Peter

    2006-01-01

    Biomorphic self-supporting MFI-type zeolite frameworks with hierarchical porosity and complex architecture were prepared using a 2-step (in-situ seeding and secondary crystal growth) hydrothermal synthesis in the presence of a biological template (Luffa sponge), employed as a macroscale sacrificial structure builder. The bio-inspired zeolitic replica inherited the complex spongy morphology and the intricate open-porous architecture of the biotemplate. Moreover, it exhibited reasonable mechanical stability in order to study the applicability of the biomorphic catalyst in a technical catalytic process. A bio-inspired catalytic reactor utilising the self-supporting ZSM-5 scaffold in monolithic configuration was developed in order to test the catalytic performance of the material

  3. Electrical conductivity of polyaniline/zeolite composites and synergetic interaction with CO

    International Nuclear Information System (INIS)

    Densakulprasert, Nataporn; Wannatong, Ladawan; Chotpattananont, Datchanee; Hiamtup, Piyanoot; Sirivat, Anuvat; Schwank, Johannes

    2005-01-01

    The effects of zeolite content, pore size and ion exchange capacity on electrical conductivity response to carbon monoxide (CO) of polyaniline/zeolite composites were investigated. Zeolite Y, 13X, and synthesized AlMCM41, all having the common cation Cu 2+ , were dry mixed with synthesized maleic acid (MA) doped polyaniline and compressed to form polyaniline (PANI)/zeolite pellet composites. The Y, 13X and AlMCM41 zeolite have the nominal pore sizes of 7, 10, 36 A, and the Cu 2+ exchange capacities of 0.161, 0.087, and 0.044 mol/g, respectively. With an addition of 13X zeolite to pristine polyaniline, the electrical conductivity sensitivity to CO/N 2 gas increases with zeolite content. For the effect of zeolite type, the highest electrical conductivity sensitivity is obtained with the 13X zeolite, followed by the Y zeolite, and the AlMCM41 zeolite, respectively. Poor sensitivity of zeolite AlMCM41 is probably due to its very large pore size and its lowest Cu 2+ exchange capacity. Y zeolite and 13X zeolite have comparable pore sizes but the latter has a greater pore free volume and a more favorable location distribution of the Cu 2+ ions within the pore. The temporal response time increases with the amount of zeolite in the composites but it is inversely related to the amount of ion exchange capacity

  4. Dry method for recycling iodine-loaded silver zeolite

    International Nuclear Information System (INIS)

    Thomas, T.R.; Staples, B.A.; Murphy, L.P.

    1978-01-01

    Fission product iodine is removed from a waste gas stream and stored by passing the gas stream through a bed of silver-exchanged zeolite until the zeolite is loaded with iodine, passing dry hydrogen gas through the bed to remove the iodine and regenerate the bed, and passing the hydrogen stream containing the hydrogen iodide thus formed through a lead-exchanged zeolite which absorbs the radioactive iodine from the gas stream and permanently storing the lead-exchanged zeolite loaded with radioactive iodine

  5. Geração de mesoporos em zeólitas ZSM-5 e seus efeitos na conversão do etanol em olefinas

    Directory of Open Access Journals (Sweden)

    Ingryd Carvalho Alves

    2012-01-01

    Full Text Available Developing mesoporosity in HZSM-5 zeolites is an alternative for improving their catalytic performance on chemical reactions. In this work, alkaline and thermal treatments were used to produce mesoporosity. These treatments increased mesoporous area and volume. They also influenced the acid properties of the samples. Concerning catalytic performance, treatments modified reaction product distribution. Whereas alkaline treatment favored formation of olefins and increased propene ratio in the beginning of the reaction, thermal treatment resulted in formation of only ethylene due to the low acidity of the sample.

  6. Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules.

    Science.gov (United States)

    Hendriks, Frank C; Schmidt, Joel E; Rombouts, Jeroen A; Lammertsma, Koop; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2017-05-05

    A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system. The developed method was extended to BEA (Beta) crystals, showing that the previously observed hourglass pattern is a general feature of BEA crystals with this morphology. Furthermore, the probes can accurately identify at which crystal faces of BEA straight or sinusoidal pores open to the surface. The results show this method can spatially resolve the architecture-dependent internal pore structure of microporous materials, which is difficult to assess using other characterization techniques such as X-ray diffraction. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  7. Catalytic reduction of NO{sub x} in gasoline engine exhaust over copper- and nickel-exchanged X-zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, S. [Indian Inst. of Technology, Kharagpur (India). Dept. of Mechanical Engineering; Das, R.K. [Indian School of Mines, Dhanbad (India). Dept. of Engineering and Mining Machinery

    2001-10-11

    Catalytic removal of NO{sub x} in engine exhaust gases can be accomplished by non-selective reduction, selective reduction and decomposition. Noble metals are extensively used for non-selective reduction of NO{sub x} and up to 90% of engine NO{sub x} emissions can be reduced in a stoichiometric exhaust. This requirement of having the stoichiometric fuel-air ratio acts against efficiency improvement of engines. Selective NO{sub x} reduction in the presence of different reductants such as, NH{sub 3}, urea or hydrocarbons, requires close control of the amount of reductant being injected which otherwise may be emitted as a pollutant. Catalytic decomposition is the best option for NO{sub x} removal. Nevertheless, catalysts which are durable, economic and active for NO{sub x} reduction at normal engine exhaust temperature ranges are still being investigated. Three catalysts based on X-zeolite have been developed by exchanging the Na+ ion with copper, nickel and copper-nickel metal ions and applied to the exhaust of a stationary gasoline engine to explore their potential for catalytic reduction of NO{sub x} under a wide range of engine and exhaust conditions. Some encouraging results have been obtained. The catalyst Cu-X exhibits much better NO{sub x} reduction performance at any temperature in comparison to Cu-Ni-X and Ni-X; while Cu-Ni-X catalyst exhibits slightly better performance than Ni-X catalyst. Maximum NO{sub x} efficiency achieved with Cu-X catalyst is 59.2% at a space velocity (sv) of 31 000 h{sup -1}; while for Cu-Ni-X and Ni-X catalysts the equivalent numbers are 60.4% and 56% respectively at a sv of 22 000 h{sup -1}. Unlike noble metals, the doped X-zeolite catalysts exhibit significant NO{sub x} reduction capability for a wide range of air/fuel ratio and with a slower rate of decline as well with increase in air/fuel ratio. (author)

  8. Phosphorus promotion and poisoning in zeolite-based materials: synthesis, characterisation and catalysis.

    Science.gov (United States)

    van der Bij, Hendrik E; Weckhuysen, Bert M

    2015-10-21

    Phosphorus and microporous aluminosilicates, better known as zeolites, have a unique but poorly understood relationship. For example, phosphatation of the industrially important zeolite H-ZSM-5 is a well-known, relatively inexpensive and seemingly straightforward post-synthetic modification applied by the chemical industry not only to alter its hydrothermal stability and acidity, but also to increase its selectivity towards light olefins in hydrocarbon catalysis. On the other hand, phosphorus poisoning of zeolite-based catalysts, which are used for removing nitrogen oxides from exhaust fuels, poses a problem for their use in diesel engine catalysts. Despite the wide impact of phosphorus-zeolite chemistry, the exact physicochemical processes that take place require a more profound understanding. This review article provides the reader with a comprehensive and state-of-the-art overview of the academic literature, from the first reports in the late 1970s until the most recent studies. In the first part an in-depth analysis is undertaken, which will reveal universal physicochemical and structural effects of phosphorus-zeolite chemistry on the framework structure, accessibility, and strength of acid sites. The second part discusses the hydrothermal stability of zeolites and clarifies the promotional role that phosphorus plays. The third part of the review paper links the structural and physicochemical effects of phosphorus on zeolite materials with their catalytic performance in a variety of catalytic processes, including alkylation of aromatics, catalytic cracking, methanol-to-hydrocarbon processing, dehydration of bioalcohol, and ammonia selective catalytic reduction (SCR) of NOx. Based on these insights, we discuss potential applications and important directions for further research.

  9. Graphene/TiO2/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    Science.gov (United States)

    Hu, Xin-Yan; Zhou, Kefu; Chen, Bor-Yann; Chang, Chang-Tang

    2016-01-01

    This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO2 loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO2), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV-vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min photocatalytic treatment, OTC solution treated by GTZ (1:8:1) showed insignificant biotoxicity to receptor DH5α cells. Furthermore, EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system. The results showed that the holes are the main oxidation species in the photocatalytic process.

  10. Direct activation of microcrystalline zeolites

    NARCIS (Netherlands)

    Ortiz-Iniesta, Maria Jesus; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    In this work a direct activation route of zeolites is assessed. It consists of NH4-exchanging the as-synthesized solids before removing the organic template. Calcination afterwards serves to combust the organic template and creates the Bronsted sites directly; thus applying merely a single thermal

  11. The selection and performance of the natural zeolite clinoptilolite in British Nuclear Fuels' site ion exchange effluent plant, SIXEP

    International Nuclear Information System (INIS)

    Baxter, S.G.; Berghauser, D.C.

    1986-01-01

    SIXEP has been conducted by British Nuclear Fuels plc at its Sellafield reprocessing site as part of its committment to reduce radioactive discharges to the Irish Sea. An extensive development program identified the natural ion exchange mineral clinoptilolite, from a particular deposit in California now owned by Tenneco Specialty Minerals, as the most suitable for use in SIXEP to extract caesium and strontium from spent nuclear fuel storage pond water. Close cooperation with the supplier in a Quality Assurance scheme ensured the supply of a fully-characterised, high grade ion exchanger. Since SIXEP commenced treating pond water on 28 May 1985, the plant has performed well, exceeding the design expectation in terms of discharge reduction and availability

  12. Graphene/TiO{sub 2}/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xin-Yan; Zhou, Kefu [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chen, Bor-Yann, E-mail: boryannchen@yahoo.com.tw [Department of Chemical and Materials Engineering, National I-Lan University, Ilan, Taiwan (China); Chang, Chang-Tang, E-mail: ctchang73222@gmail.com [Department of Environmental Engineering, National I-Lan University, Ilan, Taiwan (China)

    2016-01-30

    Graphical abstract: The mechanism of OTC degradation can be described as follows. At first, the OTC molecule was adsorbed onto the surface of GTZ material. The conduction band electron (e{sup −}) and valence band holes (h{sup +}) are generated when aqueous GTZ suspension is irradiated with visible light. The generation of (e{sup −}/h+) pair leading to the formation of reactive oxygen species. The ·OH radical and ·O{sub 2}{sup −} can oxidize OTC molecular, resulting in the degradation and mineralization of the organics. - Highlights: • Determine optimal composites of graphene, TiO{sub 2}, and zeolite for maximal photodegradation efficiency via triangular mixture design. • Unravel most promising composites for high stability and absorptive capabilities for photocatalytic degradation. • Disclose time-series profiles of toxicity of advanced oxidation processes (AOPs) treatment of wastewater. • Propose plausible routes of mechanism of photocatalytical degradation of OTC. - Abstract: This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO{sub 2} loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO{sub 2}), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV–vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min

  13. Graphene/TiO_2/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    International Nuclear Information System (INIS)

    Hu, Xin-Yan; Zhou, Kefu; Chen, Bor-Yann; Chang, Chang-Tang

    2016-01-01

    Graphical abstract: The mechanism of OTC degradation can be described as follows. At first, the OTC molecule was adsorbed onto the surface of GTZ material. The conduction band electron (e"−) and valence band holes (h"+) are generated when aqueous GTZ suspension is irradiated with visible light. The generation of (e"−/h+) pair leading to the formation of reactive oxygen species. The ·OH radical and ·O_2"− can oxidize OTC molecular, resulting in the degradation and mineralization of the organics. - Highlights: • Determine optimal composites of graphene, TiO_2, and zeolite for maximal photodegradation efficiency via triangular mixture design. • Unravel most promising composites for high stability and absorptive capabilities for photocatalytic degradation. • Disclose time-series profiles of toxicity of advanced oxidation processes (AOPs) treatment of wastewater. • Propose plausible routes of mechanism of photocatalytical degradation of OTC. - Abstract: This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO_2 loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO_2), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV–vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min photocatalytic treatment, OTC solution treated

  14. Removal of strontium ions from solutions using granulated zeolites

    International Nuclear Information System (INIS)

    Bronic, J.; Subotic, B.

    1992-01-01

    The ion-exchange process on columns filled with granulated zeolites is determined by several physico-chemical parameters. The influence of these parameters (zeolite type, concentration of exchangeable ions in solution, temperature, flow rate, etc.) on the kinetics of ion-exchange process was studied by measuring the Sr 2+ ion concentration in solution before and after passing through a column filled with various granulated zeolites (zeolite 13X, zeolite A and synthetic mordenite). Using the experimental technique of radioactive labeling by 89 Sr, the distribution of Sr 2+ ions in column fillings were also determined. From the results obtained, the optimal conditions for the most efficient removal of strontium ions from solutions using granulated zeolites can be defined. (author) 24 refs.; 9 figs

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

    Science.gov (United States)

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

    2012-08-15

    Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Influence of the desilication process on the acidity of HZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Rac, Vladislav, E-mail: vrac@ffh.bg.ac.rs [Faculty of Agriculture, Department of Chemistry, University of Belgrade, Belgrade (Serbia); Rakić, Vesna [Faculty of Agriculture, Department of Chemistry, University of Belgrade, Belgrade (Serbia); Miladinović, Zoran [Institute of General and Physical Chemistry, Belgrade (Serbia); Stošić, Dušan; Auroux, Aline [Institut de Recherches sur la Catalyse et l’Environnement de Lyon (IRCELYON), Villeurbanne (France)

    2013-09-10

    Highlights: ► Mesopore creation in three different HZSM-5 zeolites was performed via desilication. ► Acidity was assessed by microcalorimetric and thermokinetic data. ► ZSM-5 with SiO{sub 2}/Al{sub 2}O{sub 3} = 23 proved to be the least susceptable to mesopore creation. ► Acidity of samples with SiO{sub 2}/Al{sub 2}O{sub 3} = 50 and 80 remained mostly unchanged by desilication, while the surface diffusion was improved. - Abstract: The influence of the alkaline treatment on the acidity of zeolite ZSM-5 (SiO{sub 2}/Al{sub 2}O{sub 3} = 23, 50 and 80) modified by desilication was investigated. The samples were characterized by X-ray diffraction, low temperature adsorption of nitrogen and solid-state {sup 27}Al MAS NMR. Acidity of the samples was investigated using microcalorimetry-volumetry of ammonia adsorption at 423 K. Acid sites accessibility and intracrystalline diffusion were estimated by the thermokinetic parameter. The desilication process was shown to be Si/Al ratio dependant. Relative enhancement of mesopore surface decreased in the following order of SiO{sub 2}/Al{sub 2}O{sub 3}: 50 > 8 0 >23. Pore size distribution broadened and mesopore sizes increased with increasing Si/Al ratio. For samples with SiO{sub 2}/Al{sub 2}O{sub 3} = 50 and 80 almost full preservation of acid sites strength and distribution was achieved. Significant alteration of the acidity was found for the mesoporous sample with SiO{sub 2}/Al{sub 2}O{sub 3} = 23. Thermokinetic parameter values indicate facilitated intracristalline diffusion for mesoporous samples.

  17. Synthesis and Characterization of Zeolite Na−Y and Its Conversion to the Solid Acid Zeolite H−Y

    DEFF Research Database (Denmark)

    Warner, Terence Edwin; Galsgaard Klokker, Mads; Nielsen, Ulla Gro

    2017-01-01

    Zeolite Y has an iconic crystal structure, but more importantly, the hydrogen modification zeolite H−Y is the classic example of a solid acid which is used extensively as a catalyst in the oil industry. This metastable compound cannot be synthesized directly, which creates an opportunity to discuss...... various preparative strategies with the students, such as the three-stage procedure described here. Stage I concerns the hydrothermal synthesis of zeolite Na−Y, followed by ion-exchange with an ammonium acetate solution to form zeolite NH4−Y, and the latter is subsequently converted to zeolite H......−Y by thermolysis. Stages II and III may instead be performed using commercially available zeolites, Na−Y and NH4−Y, respectively, which shifts the learning objectives to structural characterization of zeolites. The characterization of the product and intermediate materials gives the students a practical insight...

  18. Natural zeolite reactivity towards ozone: The role of compensating cations

    International Nuclear Information System (INIS)

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

    2012-01-01

    Highlights: ► Chemical and thermal treatment enhances catalytic activity of natural zeolite. ► Modified natural zeolite exhibits high stability after thermal treatment. ► Reducing the compensating cation content leads to an increase on ozone abatement. ► Surface active atomic oxygen was detected using the DRIFT technique. ► The highest reactivity toward ozone was performed by NH4Z3 zeolite sample. - Abstract: Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L −1 ). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77 K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH 3 -TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  19. Natural zeolite reactivity towards ozone: The role of compensating cations

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Hector, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologias Limpias (F. Ingenieria), Universidad Catolica de la Santisima Concepcion, Alonso de Ribera 2850, Concepcion (Chile); Alejandro, Serguei; Zaror, Claudio A. [Departamento de Ingenieria Quimica (F. Ingenieria), Universidad de Concepcion, Concepcion (Chile)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Chemical and thermal treatment enhances catalytic activity of natural zeolite. Black-Right-Pointing-Pointer Modified natural zeolite exhibits high stability after thermal treatment. Black-Right-Pointing-Pointer Reducing the compensating cation content leads to an increase on ozone abatement. Black-Right-Pointing-Pointer Surface active atomic oxygen was detected using the DRIFT technique. Black-Right-Pointing-Pointer The highest reactivity toward ozone was performed by NH4Z3 zeolite sample. - Abstract: Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L{sup -1}). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77 K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH{sub 3}-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  20. Oxygen-containing coke species in zeolite-catalyzed conversion of methanol to hydrocarbons

    KAUST Repository

    Liu, Zhaohui

    2016-10-06

    Zeolites are the most commonly used catalysts for methanol-to-hydrocarbon (MTH) conversion. Here, we identified two oxygen-containing compounds as coke species in zeolite catalysts after MTH reactions. We investigated the possible influences of the oxygen-containing compounds on coke formation, catalyst deactivation, product selectivity, and the induction period of the MTH reaction through a series of controlled experiments in which one of the identified compounds (2,3-dimethyl-2-cyclopenten-1-one) was co-fed with methanol over a zeolite H-ZSM-5 catalyst. Our results allow us to infer that once produced, the oxygen-containing compounds block the Brønsted acid sites by strong chemisorption and their rapid conversion to aromatics expedites the formation of coke and thus the deactivation of the catalyst. A minor effect of the production of such compounds during the MTH reaction is that the aromatic-based catalytic cycle can be slightly promoted to give higher selectivity to ethylene.

  1. Metal compounds in zeolites as active components of chemisorption and catalysis. Quantum chemical approach

    International Nuclear Information System (INIS)

    Zhidomirov, G.M.

    1996-01-01

    A short review of possible catalitic active sites associated with various types of metal species in zoolite is presented. The structural and electronic peculiarity of aluminum ions in zeolite lattice and their distribution in the lattice are discussed on the basis of quantum chemical calculations in connection with the formation of Broensted activity of zeolites. Various molecular models of Lewis Acid Sites associated the extra-lattice oxide-hydroxide aluminum species have been investigated by means of density functional model cluster calculations using CO molecule as a probe. Probable ways of formation of the selective oxidation center in FeZSM-5 by decomposition of dinitrogen monoxide have been studied by ab-initio quantum chemical calculations. The immediate oxidizing site is reasonably represented by the binuclear iron-hydroxide cluster with peroxo-like fragment located between iron atoms. Various probable intermediates of the selective oxidation center formation resulted from interaction of a hydroperoxide molecule with a lattice titanium ion in titanium silicalite have been investigated by quantum chemical calculations. It was concluded that this reaction requires essential structural reconstruction in the vicinity of the titanium ion. Probability of this structural reconstruction is discussed. Possible reasons of an electron-deficient and electron-enriched state of metal particles entrapped in zoolite cavities are discussed. Also, various probable molecular models of such modified metal particles in zeolite are considered

  2. The assessment of pore connectivity in hierarchical zeolites using positron annihilation lifetime spectroscopy: instrumental and morphological aspects.

    Science.gov (United States)

    Zubiaga, Asier; Warringham, Robbie; Boltz, Marilyne; Cooke, David; Crivelli, Paolo; Gidley, David; Pérez-Ramírez, Javier; Mitchell, Sharon

    2016-04-07

    Recent studies demonstrated the power of positron annihilation lifetime spectroscopy (PALS) to characterise the connectivity and corresponding effectiveness of hierarchical pore networks in zeolites. This was based on the fractional escape of ortho-positronium (Ps), formed within the micropore framework, to vacuum. To further develop this technique, here we assess the impact of the positron implantation energy and of the zeolite crystal size and the particle morphology. Conventional measurements using fast positrons and beam measurements applying moderated positrons both readily distinguish purely microporous ZSM-5 zeolites comprised of single crystals or crystal aggregates. Unlike beam measurements, however, conventional measurements fail to discriminate model hierarchical zeolites with open or constricted mesopore architectures. Several steps are taken to rationalise these observations. The dominant contribution of Ps diffusion to the PALS response is confirmed by capping the external surface of the zeolite crystals with tetraethylorthosilicate, which greatly enhances the sensitivity to the micropore network. A one-dimensional model is constructed to predict the out-diffusion of Ps from a zeolite crystal, which is validated experimentally by comparing coffin-shaped single crystals of varying size. Calculation of the trends expected on the application of fast or moderated positrons indicates that the distinctions in the initial distribution of Ps at the crystal level cannot explain the limited sensitivity of the former to the mesopore architecture. Instead, we propose that the greater penetration of fast positrons within the sample increases the probability of Ps re-entry from intercrystalline voids into mesopores connected with the external surface of zeolite crystals, thereby reducing their fractional escape.

  3. Nuclear waste treatment using Iranian natural zeolites

    International Nuclear Information System (INIS)

    Kazemian, H.; Ghannadi Maraghe, M.

    2001-01-01

    Full text: The zeolite researches in Iran is a relatively new subject which has started about 10 years ago. The motivation for this scientific and interesting field was provided after discovery of significant deposits of natural zeolites in different regions of Iran as well as further developments of research institutions and the national concern to environmental protection especially the wastewater clean-up in point of view of recycling of such waste water to compensate some needs to water in other utilizations. This paper intends to review and describes scientific researches which have done on using zeolites in the field of nuclear waste treatment in Iran to introduce the potential resources to the world in more details. Zeolite tuffs are widely distributed in huge deposits in different regions of Iran. So far, the clinoptilolite tuffs are the most abundant natural zeolite which exist with zeolite content of 65%- 95%. Nowadays several different types of Iranian natural zeolites are characterized in point of view of chemical composition, type of structure, chemical, thermal, and radiation resistance using different instrumental and classical methods such as; X-ray diffraction (XRD), X-ray fluoresce (XRF), thermal methods of analysis (TA), scanning electron microscopy (SEM), analytical chemistry and radioanalytical methods as well as different ion-exchange techniques (e.g.3-7). The ability of Iranian natural clinoptilolite for removal of some fission products from nuclear wastewaters have been investigated. The selectivity of all investigated zeolites toward radiocesium and radiostrontium have been promising (e.g. 8-10). The successful synthesize of P zeolite from Iranian clinoptilolite-reach tuffs under different conditions were performed. The compatibility of zeolites with glass and cement matrices, for final disposal of radwaste, as well as their selectivity toward most dangerous heat generating radionuclides (e.g. 137 Cs and 90 Sr) is very important in using

  4. Structure of a carbon monoxide adduct of cobalt-exchanged zeolite A (Co/sub 5.25/Na/sub 1.5/-A x 1.5CO) by neutron profile refinement

    International Nuclear Information System (INIS)

    Adams, J.M.; Haselden, D.A.

    1984-01-01

    The structure of a carbon monoxide adduct of cobalt-exchanged zeolite A, Co/sub 5.25/Na/sub 1.5/-A x 1.5CO, has been determined by Rietveld neutron profile refinement. All exchangeable cations are located in sites adjacent to the 6-ring; 3.75 of the cobalt cations sit 0.4 A inside the β-cage (Co(2)) and are arranged tetrahedrally about the eight 6-rings sites in the β-cage. The sodium cations (Na(1)) reside just inside the α-cage in sites similar to those found previously for zeolites 3A, 4A, and 5A. The remaining 1.5 cobalt cations (Co(1)) are located in sites similar to those for sodium, but they are also coordinated to the carbon monoxide molecules, which lie on, or close-to, the threefold axis which passes through the 6-ring. Inside the β-cage there is a tetrahedral aluminum complex of AlO 4 type, the oxygen atoms (O*) of which point toward six rings not occupied by cobalt cations, Co(2). Each of the oxygen atoms of this complex is involved in a hydrogen bond (2.83 A) to the 6-ring oxygen O(3). Approximately 2/3 of these bonds are of type O*-H ... O(3) and 1/3 of type O* ...H-O(3)

  5. Effect of rare earth cations on activity of type Y zeolites in ethylene transformations

    International Nuclear Information System (INIS)

    Amezhnova, G.N.; Zhavoronkov, M.N.; Dorogochinskij, A.Z.; Proskurin, A.L.; Shmailova, V.I.

    1984-01-01

    The ethylene transformations on type Y rare earth zeolites with high degrees of sodium exchange are studied. It is shown that rare earth cations increase zeolites activity with growth of electronoacceptor capacity. The ethylene oligomerization occurs on polyvalent cations while subsequent oligomer transformations - on hydroxyl groups of zeolites

  6. Templating mesoporous zeolites

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Christensen, Christina Hviid; Kustova, Marina

    2008-01-01

    The application of templating methods to produce zeolite materials with hierarchical bi- or trimodal pore size distributions is reviewed with emphasis on mesoporous materials. Hierarchical zeolite materials are categorized into three distinctly different types of materials: hierarchical zeolite...... crystals, nanosized zeolite crystals, and supported zeolite crystals. For the pure zeolite materials in the first two categories, the additional meso- or macroporosity can be classified as being either intracrystalline or intercrystalline, whereas for supported zeolite materials, the additional porosity...... originates almost exclusively from the support material. The methods for introducing mesopores into zeolite materials are discussed and categorized. In general, mesopores can be templated in zeolite materials by use of solid templating, supramolecular templating, or indirect templating...

  7. Characterisation of poly(methacrylates) formed inside zeolites by gamma irradiation

    International Nuclear Information System (INIS)

    Kwiatkowski, J.; Whittaker, A.K.

    1996-01-01

    Full text: Inclusion polymerisation was first developed in the second half of the 50's as an alternative to Ziegler-Natta co-ordination polymerisation to obtain highly stereo-regular polymers. Inclusion polymerisation was performed in organic clathrates such as thio-urea channels. However the channels are only stable when formed around the monomer. This means there is a specific concentration of monomer, namely saturation, for which the host/channel system can exist. There is also a limited number of monomers which are suitable for use with a given clathrate and the channel dimension is not usually a variable parameter for a given monomer/clathrate system. One exception is Tris(o-phenolenedioxy)cycotriphosphazene. Initiation of the monomer can be easily achieved by high energy irradiation and many of the polymers obtained show considerable chemical and steric regularity. For example poly (2,3 -dimethylbutadiene) obtained by polymerisation in a thio-urea inclusion compound has only the 1,4 trans structure and is highly crystalline. The restriction on the number of clathrate and monomer systems has lead us to investigate the use of zeolites as hosts for inclusion compounds. Zeolites exist independently of any included guest compound. They are aluminosilicate compounds whose structures form molecular-dimension channels and belong to a class of materials known as molecular sieves. Channel structures can be in 1,2 or 3 dimensions. The structural aluminium in the zeolite creates a negative charge on the lattice which is balanced by cations. In this study we have diffused methyl and ethyl methacrylate into Na-ZSM5, Beta, Y and Mordenite zeolites. The samples where irradiated under vacuum and then extracted. The structures of the exrtracted polymer have been characterized by GPC, NMR and DSC The results will be correlated as a function of the channel size of the zeolite and compared to the bulk system

  8. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  9. Polyphosphates substitution for zeolite to in detergents

    International Nuclear Information System (INIS)

    Restrepo V, Gloria M.; Ocampo G, Aquiles; Saldarriaga M, Carlos

    1996-01-01

    The detergents, as well as the cleaning products, contain active ingredients that are good to increase their efficiency and some of them, as the sodium Tripoli-phosphate (TPF), they have turned out to be noxious for the environment. The zeolites use in the formulation of detergents has grown substantially since they fulfill the same function of the TPF and they have been recommended ecologically as substitutes from these when not being polluting. The objective of this work is to obtain a zeolite with appropriate characteristics for its use in the formulation of detergents, reproducing those of the zeolites used industrially. The zeolite synthesis is studied 4A starting from hydro-gels of different composition, varying the operation conditions and using two raw materials: (sodium meta-silicate, commercial degree and metallic aluminum) and clay type kaolin like silica source and aluminum It is looked for to get a product of beveled cubic morphology, or spherical, with glass size between 1 and 3 microns and that it possesses good capacity of conical exchange. Since the capacity and speed of ionic exchange is influenced by the particle size, time of contact and temperature, experimentation conditions settle down to measure the exchange of ions calcium and magnesium in watery solutions that they simulate the real situation of a laundry process in the country. This way the ability of the zeolite 4A obtained to diminish the concentration of these ions in the laundry waters is evaluated and its possibilities like component in the formulation of detergents non-phosphatates. Of the synthesized zeolites, the best in agreement is chosen with chemical properties as ionic and physical exchange capacity as crystalline, particle size and color, to prepare a detergent in which the polyphosphates is substituted partial and totally for the synthesized zeolite

  10. Mixing of zeolite powders and molten salt

    International Nuclear Information System (INIS)

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

    1996-01-01

    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

  11. Exceptionally stable and hierarchically porous self-standing zeolite monolith based on a solution-mediated and solid-state transformation synergistic mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Do, Manh Huy [Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Zhejiang University, Hangzhou 310027, Zhejiang (China); College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Institute of Chemical Technology, Vietnamese Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh (Viet Nam); Cheng, Dang-guo, E-mail: dgcheng@zju.edu.cn [College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Chen, Fengqiu [Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Zhejiang University, Hangzhou 310027, Zhejiang (China); College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhan, Xiaoli [College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China)

    2015-11-15

    Although many strategies exist for fabricating hierarchical zeolite monolith, it is still challenging to synthesize pure hierarchical zeolite monolith with intracrystalline meso-/macropores and stability suitable for industrial application in a general and efficient process. Here we describe a simple quasi-solid gel crystallization route to prepare hierarchical self-standing ZSM-5 zeolite monolith via the use of Na{sup +} and OH{sup −} as counterions to modify the breaking and remaking of T–O–T (T = Si or Al) bonds. X-ray diffraction (XRD), scanning electron microcopy (SEM), transmission electron microscopy (TEM), laser scan confocal microscopy (LSCM), N{sub 2} adsorption–desorption, mercury porosimetry, solid-state nuclear magnetic resonance (NMR), and compression mechanical testing were applied to elucidate the structure and mechanical stability of the obtained monolith. The self-standing monolith is composed of self-interconnected meso-/macroporous MFI crystals with tunable intracrystalline meso-/macropores and possesses an unusually mechanical stability with a crushing strength of 5.01 MPa. Combined with controllable structure of the defect-free membrane layer on the monolith top, the self-standing zeolite monolith should widen their potential applications. - Highlights: • Hierarchical self-standing MFI zeolite monoliths were synthesized via a facile method. • Na{sup +} and OH{sup −} are used as counterions for breaking and remaking of T–O–T (T = Si or Al) bonds. • Hierarchical self-standing MFI zeolite monoliths result from zeolite crystal intergrowth. • Self-standing zeolite monolith has an excellent mechanical stability with tunable intracrystalline meso-/macropores.

  12. High Zn/Al ratios enhance dehydrogenation vs hydrogen transfer reactions of Zn-ZSM-5 catalytic systems in methanol conversion to aromatics

    DEFF Research Database (Denmark)

    Pinilla-Herrero, Irene; Borfecchia, Elisa; Holzinger, Julian

    2018-01-01

    suggest that catalytic activity is associated with [Zn(H2O)n(OH)]+ species located in the exchange positions of the materials with little or no contribution of ZnO or metallic Zn. The effect of Zn/Al ratio on their catalytic performance in methanol conversion to aromatics has been investigated. In all...... cases, higher Zn content causes an increase in the yield of aromatics while keeping the production of alkanes low. For similar Zn contents, high densities of Al sites favour the hydrogen transfer reactions and alkane formation whereas in samples with low Al contents, and thus higher Zn/Al ratio...

  13. Possibility of Modification of Zeolites by Iron Oxides and its Utilization for Removal of Pb(II from Water Solutions

    Directory of Open Access Journals (Sweden)

    Michal Lovás

    2004-12-01

    Full Text Available Ion-exchange properties of cations from lattice and ions from solutions are characteristic for zeolites. Zeolites as sorbents are used in many branches of industry. Ion-exchange reactions of cations on zeolites have been a theme of many works. With the exception of using natural zeolites as the sorbent, a modification of surface of zeolites and preparation of synthetic zeolites has received interest lately. One of the common modification of zeolites is modification by iron oxides, which increases capacity of adsorption. In this work, we prepared a modified zeolite by the precipitation of magnetite on the surface of zeolite. This new adsorbent was used to remove of Pb(II from waste water. The maximum adsorption capacity was 73,25 mg/g from the solution of Pb with the concentration of 400 mg/l.

  14. Human bile sorption by cancrinite-type zeolites

    International Nuclear Information System (INIS)

    Linares, Carlos F.; Colmenares, Maryi; Ocanto, Freddy; Valbuena, Oscar

    2009-01-01

    A nitrated cancrinite-type zeolite was synthesized from zeolite X, NaOH and NaNO 3 solutions under autogeneous pressure at 80 deg. C for 48 h. This zeolite was characterized by X-ray diffraction (XRD), FT-IR-spectroscopy, scanning electron microscopy (SEM) and BET surface area. XRD, SEM and FT-IR confirmed the presence of nitrated cancrinite-type zeolite without other collateral phases as sodalite. Then, this sodium zeolite was exchanged with potassium and calcium cations and finally, these modified zeolites were reacted with biliar solutions from human gallbladder. Several factors such as: mass of used cancrinite, nature of the exchanged cation and reaction time of the cancrinite-bile solution interactions were studied. The composition of bile solutions (bile acids, phospholipids and bilirubin) was analyzed before and after the cancrinite-bile solution reaction. Results showed that the components of the bile were notably reduced after the contact with solids. Ca-cancrinite, 120 min of reaction time and 500 mg of solids were the best conditions determined for the bile acid reduction in human bile. When the modified zeolites were compared with the commercial cholestyramine, it was found that zeolites were more active than the latter. These zeolites may be an alternative choice to diminish cholesterol levels in hypercholesterolemic patients

  15. Fly ash based zeolitic pigments for application in anticorrosive paints

    International Nuclear Information System (INIS)

    Shaw, Ruchi; Tiwari, Sangeeta

    2016-01-01

    The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na + with Mg 2+ and Ca 2+ ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxy resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).

  16. Positron spectroscopy studies of zeolites

    Science.gov (United States)

    Hung, Ku-Jung

    The lineshapes of two-dimensional angular correlation of electron-positron annihilation radiation (2D-ACAR) in alumina and several zeolites were measured as a function of internal surface areas. In all cases, the lineshape parameter S from 2D-ACAR spectra were found to vary proportionally with internal surface area. In order to investigate the Bronsted acidity in NaHY zeolite, the lineshape parameter evaluation from 2D-ACAR measurements for varied acidity in NaHY zeolites by ion-exchange and thermal desorption were presented. The result from this investigation has demonstrated that the Bronsted acidity in NaHY zeolite was found to vary linearly with the lineshape parameter of the angular correlation spectrum of the sample. The lineshapes of 2D-ACAR spectra were determined for different base adsorbed HY-zeolite samples under a temperature controlled heating system in order to investigate, in-situ, the acid strength and number of Bronsted acid sites in the sample. Results have shown that the lineshape parameter of the angular correlation spectrum of the sample increases with the strength of adsorbed base and decreases with the number of Bronsted acid sites in the sample. This indicated that the lineshape parameter is sensitive to all of the strengths and concentrations of Bronsted acid sites in the HY-zeolite samples. The result from this study has also demonstrated that the large size base, pyridine, would reduce the possibility of positronium formation in the sample by filling the cage to eliminate the internal surface areas where the positroniums are likely to form. However, the small size base, ammonia, did not show any effect on the internal surface areas. Owing to the fact that this technique monitors only the Bronsted acid sites that situate on the surface which relates to the catalytic activity, there is little ambiguity about the location of the source of information obtained. The findings presented in this dissertation point out the fact that such lineshape

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

    Science.gov (United States)

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

    2013-10-11

    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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. An alternative preparation method for ion exchanged catalysts: Solid state redox reaction

    DEFF Research Database (Denmark)

    Schneider, E.; Hagen, A.; Grunwaldt, J.-D.

    2004-01-01

    A new method for modifying zeolites with zinc is proposed. The solid state redox reaction between metallic zinc and ZSM-5 zeolites with different Si/Al ratios was investigated by temperature programmed hydrogen evolution (TPHE), X-ray absorption near edge structure (XANES) and diffuse reflectance...... infrared Fourier transform spectroscopy (DRIFTS). The evolution of hydrogen was detected at temperatures above 620 K. The source of hydrogen was the solid state redox reaction of the metal with protons of the support. The samples exhibit catalytic activity in ethane aromatization indicating that zinc...... should be located at the same sites as in catalysts prepared by conventional methods. Combination of XANES and catalytic activity point to zinc being mainly present in tetrahedral geometry under reaction conditions....

  19. Method of processing radioactive liquid wastes by using zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Kanno, T; Mimura, H

    1975-09-18

    The object is to processing radioactive liquid waste by zeolites to be fixed to a solidified body having a very small lixiviation property. The nuclide in radioactive liquid waste is exchanged and adsorbed into natural or synthetic zeolites, which are then burnt to a temperature lower than 1000/sup 0/C -- melting point. Thus, the zeolite structure is broken to form fine amorphous silicate aluminate or silicate aluminate of the nuclide exchanged and adsorbed. Both are very hard to be soluble in water. Further, the lixiviation from the solidified body is limited to the surface thereof, and it will no longer be detected in a few days.

  20. Sorption of 60 Co in natural zeolite (clinoptilolite)

    International Nuclear Information System (INIS)

    Hernandez B, E.

    1996-01-01

    A Mexican zeolite (clinoptilolite) from Taxco, Guerrero, was partially stabilized with sodium cations. Radioactive Cobalt ( 60 Co) was used to study the Co 2+ sorption in the stabilized zeolite (Na + ). It was found that sorption in general does not favour the diffusion of cobalt between framework, it explains because of it is a natural zeolite and its composition heterogeneous decrease its exchange capacity by the generated competence to the existence other type of exchange ions. The cobalt retention reached the highest level, around 0.408 m eq Co 2+ /g in the Na-Clinoptilolite. The crystallinity of the aluminosilicates was maintained during experiments, it was verified by XRD patterns. (Author)

  1. Properties of glass-bonded zeolite monoliths

    International Nuclear Information System (INIS)

    Lewis, M.A.; Fischer, D.F.; Murphy, C.D.

    1994-01-01

    It has been shown that mineral waste forms can be used to immobilize waste salt generated during the pyrochemical processing of spent fuel from the Integral Fast Reactor (IFR). Solid, leach resistant monoliths were formed by hot-pressing mixtures of salt-occluded zeolite A powders and glass frit at 990 K and 28 MPa. Additional samples have now been fabricated and tested. Normalized release rates for all elements, including iodide and chloride, were less than 1 g/m 2 d in 28-day tests in deionized water and in brine at 363 K (90 degrees C). Preliminary results indicate that these rates fall with time with both leachants and that the zeolite phase in the glass-bonded zeolite does not function as an ion exchanger. Some material properties were measured. The Poisson ratio and Young's modulus were slightly smaller in glass-bonded zeolite than in borosilicate glass. Density depended on zeolite fraction. The glass-bonded zeolite represents a promising mineral waste form for IFR salt

  2. Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

    Directory of Open Access Journals (Sweden)

    Zeeshan Nawaz

    2009-12-01

    Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

  3. Catalytic pyrolysis of wheat bran for hydrocarbons production in the presence of zeolites and noble-metals by using TGA-FTIR method.

    Science.gov (United States)

    Lazdovica, K; Liepina, L; Kampars, V

    2016-05-01

    Pyrolysis of wheat bran with or without catalysts was investigated using TGA-FTIR method in order to determine the influence of zeolite and noble metal catalysts on the evolution profile and relative yield of the volatile compounds. The addition of all catalysts decreased the volatile matter of wheat bran from 76.3% to 75.9%, 73.9%, 73.5%, 69.7% and increased the solid residue from 18.0% to 18.4%, 20.4%, 20.8%, 24.6% under the catalyst of ZSM-5, 5% Pd/C, MCM-41, and 5% Pt/C. Noble-metal catalysts had higher activity for deoxygenation of compounds containing carbonyl, carboxyl, and hydroxyl groups than zeolites. Degradation of nitrogen containing compounds atom proceeded better in presence of zeolites. Noble-metal catalysts promoted formation of aromatics and changed the profiles of evolved compounds whereas zeolites advanced formation of aliphatics and olefins. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Isobutane/2-butene alkylation with zeolite Y without BrÆnsted acidity

    OpenAIRE

    Rosenbach Jr,Nilton; Mota,Claudio J. A.

    2005-01-01

    Alkylation of isobutane with 2-butene was performed on metal-exchanged Y zeolites, using an alkylchloride as carbocation initiator. The results indicated that, compared with a protonic zeolite, the deactivation was significantly slower and the production of trimethylpentanes was higher on the metal-exchanged zeolites. The metal cations act as Lewis acids, interacting with the chloride initiating the carbocationic reactions. The results also support the view that protonic sites on the catalyst...

  5. Modification of Natural Zeolite with Fe(III) and Its Application as Adsorbent Chloride and Carbonate ions

    Science.gov (United States)

    Suhartana; Sukmasari, Emmanuella; Azmiyawati, Choiril

    2018-04-01

    The aim of the research is to natural zeolite with Fe(III) using anion exchange process to improve the anion exchange capacity. Natural zeolite was activated using HNO3 1 N and then mixed with FeCl3 solution and refluxed followed by oven and calcination at a temperature of 550°C. The influence of Fe(III) to zeolite was characterized by FTIR while presence of Fe in zeolite characterized by AAS. Zeolite and Zeolite-Fe adsorption capacity of chloride and carbonate anions were determined through adsorption test by variation of pH and contact time. In advanced, and then to determining the Fe adsorbed concentration at Zeolite using UV-Vis spectrophotometer. FTIR analysis result showed that the addition of Fe does not affect the zeolite’s structure but change the intensity of the zeolite spectra. The Fe concentration in Zeolite-Fe of 714 mg L-1, indicate that Fe was present in the zeolite. Both Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Chloride anion is 2, with adsorption capacity 2,33 x 10-3 gg-1 and optimum contact time is 8 minutes. While Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Carbonate anion is 5, with adsorption capacity 5,31 x 10-3 gg-1 and optimum contact time is 8 minutes.

  6. Site blocking in silver-exchanged zeolite Y by carbon monoxide and ethene using xenon adsorption and 129Xe NMR spectroscopy

    Science.gov (United States)

    Boddenberg, B.; Watermann, J.

    1993-03-01

    The adsorption isotherms and 129Xe NMR chemical shifts of xenon in the zeolites NaY, AgY, and in AgY preloaded with ≈ 1 molecule/supercage ethene and carbon monoxide were measured at 25°C. The experimental data reveal the blocking of the silver-cation sites for xenon by the preadsorbed molecules. Ethene and CO are found to block the previously postulated two types of silver-cation species in the supercages of AgY in a different way.

  7. ZEOLITIZATION OF SEWAGE SLUDGE ASH WITH A FUSION METHOD

    Directory of Open Access Journals (Sweden)

    Jolanta Latosińska

    2016-11-01

    Full Text Available The study shows the results of zeolitization of municipal sewage sludge ash with the indirect fusion method followed by a hydrothermal method. The zeolitization of sewage sludge ash was conducted at the melting temperature of 550°C and the melting time of 60 minutes, crystallization temperatures of 60°C and 90°C, crystallization time of 6 hours and the SSA:NaOH ratio of 1:1.8; 1:1.4. The research of modified sewage sludge ashes included the observation of changes of ash particles surface and the identification of crystalized phases. The zeolitization of sewage sludge ash at the ratio of SSA:NaOH 1.0:1.4 did not cause the formation of zeolite phases. On the other hand, the zeolitization at the ratio of SSA:NaOH 1.0:1.8 resulted in the formation of desired zeolite phases such as zeolite Y (faujasite and hydroxysodalite. The presented method of sewage sludge ash zeolitization allows to obtain highly usable material. Synthesized zeolites may be used as adsorbents and ion exchangers. They can be potentially used to remove heavy metals as well as ammonia from water and wastewater.

  8. Preparation of Synthetic Zeolites from Myanmar Clay Mineral

    International Nuclear Information System (INIS)

    Phyu Phyu Win

    2004-04-01

    Faujasite type zeolite X was successfully synthesized from Myanmar clay mineral kaolinite, by treating with sodium hydroxide at 820 C followed by dissolution in water and hydrothermal treatment. It was found that the solution of fused clay powder can be crystallized at 90C under ambient pressure to synthesize faujasite type zeolite X. The effects of aging time and the amount of water on the formation of the product phase and Si/ Al ratios of the resulting products were investigated. Most of the Si and Al components in kaolinite might be dissolved into an alkaline solution and reacted to form ring-like structures. Then it was effectively transformed into zeolite materials. The maximum relative crystallinity of faujasite zeolite obtained was found to be 100%. Zeolite P was found to be a competitive phase present in some resulting products during hydrothermal treatment. The cation exchange capacity of kaolinite is very low, but increased after a proper treatment. It was found that the prepared faujasite type zeolite X, zeolite P and hydrogen zeolite (HZ) can reduce the hardness, the alkalinity, the total dissolved solid and the dissolved iron of raw water in the batch wise operation of water treatment. Therefore, it can be used as the cation exchanged resin for water treatment

  9. Development of spent salt treatment technology by zeolite column system. Performance evaluation of zeolite column

    International Nuclear Information System (INIS)

    Miura, Hidenori; Uozumi, Koichi

    2009-01-01

    At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)

  10. Detergents - Zeolites and Enzymes Excel Cleaning Power

    Indian Academy of Sciences (India)

    Presently used detergent formulations generally consist of surfactants, builder and cobuilder, bleaching agents, addi- tives for secondary benefits and enzymes. Zeolites are basically hydrated crystalline aluminium silicates which function as ion exchangers and make the water soft by removing calcium, magnesium and ...

  11. Zeolites and clays behavior in presence of radioactive solutions

    International Nuclear Information System (INIS)

    Carrera Garcia, L.M.

    1991-01-01

    Natural aluminosilicates have found application as selective ion exchangers for radioactive cations, present in liquid wastes arising from nuclear facilities. Among severals cations and complex mixtures of them, Co is a common constituent of liquid radioactive wastes. Two types of zeolites (Y zeolite, and natural mexican erionite), and two types of clays (natural bentonite, and Al-expanded bentonite (Al-B) were used. Previous to the experiments, the zeolites and the natural bentonite were stabilized to their respective Na + form using 5N NaCl solution. 2Na + → 60 Co 2+ ion exchange kinetics in zeolites and clays was followed by gamma spectrometry using a NaCl-Co(NO 3 ) 2 isonormal solution (0.1N) labeled with 60 Co-Co(NO 3 ) 2 (100 μ Ci). Before and after experiments, the structural changes in the cristallinity of aluminosilicates were determined by X-ray diffraction. XRD analyzes show that the cristallinity of the aluminosilicates was not affected by ion exchange. After Co exchange the cell parameters were determined in all samples. The efficiency of zeolites, natual clays and expanded clays to remove cobalt ions from solutions depends on the ion echange capacity of the material. Results for long contacts time, 18 days, show that Co is more effectively removed by Y zeolite ( 4.07 wt %), followed by erionite (3.09 wt %), then bentonite ( 2.36 wt %) and finally expanded bentonite ( 0.70 wt %). In Y zeolite an unusual fast soportion uptake of 4.51 % wt Co was observed followed by a desorption process to 4.07 %. This effect is due to the different hydration degree of zeolites during the contact time between the zeolite and the 60 Co solution. In erionite the exchange is lower than in Y-zeolite, frist because the Si/Al ratio is higher for erionite than for Y-zeolite and second because K ions in erionite cannot be exchanged during the stabilization of erionite in 5N NaCl solution. The low exchange in expanded bentonite was expected because its cation exchange

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

    Science.gov (United States)

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

    2014-06-15

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Pengaruh Kandungan Ca Pada Cao-zeolit Terhadap Kemampuan Adsorpsi Nitrogen

    OpenAIRE

    M Nasikin; Tania Surya Utami; Agustina TP Siahaan

    2002-01-01

    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 CaO-zeolite with Ca concentration = 0,682%, 0,849% and 1,244% to oxygen and nitrogen with ...

  14. Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

    International Nuclear Information System (INIS)

    Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

    1978-01-01

    In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

  15. Electron irradiation of zeolites

    International Nuclear Information System (INIS)

    Wang, S.X.; Wang, L.M.; Ewing, R.C.

    1999-01-01

    Three different zeolites (analcime, natrolite, and zeolite-Y) were irradiated with 200 keV and 400 keV electrons. All zeolites amorphized under a relatively low electron fluence. The transformation from the crystalline-to-amorphous state was continuous and homogeneous. The electron fluences for amorphization of the three zeolites at room temperature were: 7.0 x 10 19 e - /cm 2 (analcime), 1.8 x 10 20 e - /cm 2 (natrolite), and 3.4 x 10 20 e - /cm 2 (zeolite-Y). The different susceptibilities to amorphization are attributed to the different channel sizes in the structures which are the pathways for the release of water molecules and Na + . Natrolite formed bubbles under electron irradiation, even before complete amorphization. Analcime formed bubbles after amorphization. Zeolite-Y did not form bubbles under irradiation. The differences in bubble formation are attributed to the different channel sizes of the three zeolites. The amorphization dose was also measured at different temperatures. An inverse temperature dependence of amorphization dose was observed for all three zeolites: electron dose for amorphization decreased with increasing temperature. This unique temperature effect is attributed to the fact that zeolites are thermally unstable. A semi-empirical model was derived to describe the temperature effect of amorphization in these zeolites

  16. Positron annihilation in modified zeolites LTA and 13X

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Prieto, A.; Garcia-Sosa, I.; Jimenez-Becerril, J. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Col. Escandon, Del. M. Hidalgo, Mexico D. F., c. p. 11801 (Mexico); Lopez-Castanares, R.; Olea-Cardoso, O. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Paseo Tollocan esquina paseo Tollocan, esquina paseo Colon, Toluca, c. p. 50120, Estado de Mexico (Mexico)

    2007-07-01

    The pick-off annihilation lifetimes of o -Ps, {tau}{sub po}, in dehydrated Co{sup 2+} and Mn{sup 2+} exchanged zeolites LTA, in dehydrated Co{sup 2+} exchanged zeolite 13X, and in dehydrated Na{sup +} zeolites LTA and 13X, are estimated. Although {tau}{sub po} can be estimated from the lifetime spectra of the cation exchanged zeolites LTA and 13X, this lifetime can not be estimated from those spectra of Na{sup +} zeolite LTA unambiguously. The estimated pick-off lifetimes due to the annihilation of o-Ps in the internal walls of the zeolites are systematically lower than the average lifetime of p-Ps and o-Ps in vacuum {tau}{sub a}=0.5 ns. Since the pick-off process of o-Ps occurs particularly on the internal cavity walls of dehydrated zeolites, the replacement of {tau}{sub a} by {tau}{sub po} within the classical model of Tao-Eldrup to calculate cavity radius should provide more realistic cavity radii of these porous materials than when using {l_brace}{tau}{sub a}{r_brace}. This suggestion is supported by previous and present results. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Detection and Quantification of 4-Methylimidazole in Cola by Matrix-assisted Laser Desorption Ionization Mass Spectrometry with Fe2O3 Nanoparticles on Zeolite.

    Science.gov (United States)

    Fujii, Yosuke; Ding, Yuqi; Umezawa, Taichi; Akimoto, Takafumi; Xu, Jiawei; Uchida, Takashi; Fujino, Tatsuya

    2018-01-01

    Food additives generally used in carbonated drinks, such as 4-methylimidazole (4MI), caffeine (Caf?), citric acid (CA), and aspartame (Apm), were measured by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) using nanometer-sized particles of iron oxide (Fe 2 O 3 NPs). The quantification of 4MI in Coca Cola (C-cola) was carried out. In order to improve the reproducibility of the peak intensities, Fe 2 O 3 NPs loaded on ZSM5 zeolite were used as the matrix for quantification. By using 2-ethylimidazole (2EI) as the internal standard, the amount of 4MI in C-cola was determined to range from 88 to 65 μg/355 mL. The results agree with the published value (approx. 72 μg/355 mL). It was found that MALDI using Fe 2 O 3 was applicable to the quantification of 4MI in C-cola.

  18. Detergent zeolite filtration plant

    OpenAIRE

    Stanković Mirjana S.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for detergent zeolite filtration plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with a capacity of 75,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production, from 50,000 to 100,000 t/y. The main goal was to increase the detergent zeoli...

  19. CO hydrogenation on zeolite-supported Ru: Effect of neutralizing cations

    International Nuclear Information System (INIS)

    Oukaci, R.; Wu, J.C.S.; Goodwin, J.G. Jr.

    1986-01-01

    Previous results for zeolite-supported Ru prepared by ion exchange suggested a possible effect of the nature and concentration of the neutralizing cations in the zeolite on the catalytic properties of the metal. However, the interpretation of these results was complicated by the fact that a series of zeolites with different Si/Al ratios was used. The present study was undertaken to investigate systematically the influence of the nature of alkali neutralizing cations on CO hydrogenation over ion-exchanged Y-zeolite-supported ruthenium catalysts

  20. Cupric natural zeolites as microbic ides

    International Nuclear Information System (INIS)

    Contreras A, D.; Olguin G, M. T.; Alcantara D, D.; Burrola A, C.

    2009-01-01

    The Escherichia coli and the Candida albicans are considered contamination indicators for what these organisms reflect the water quality. The natural zeolites by their characteristics and properties, they could incorporate to a waters treatment system, as ion exchange, adsorbents and/or microbiocid agents, representing an alternative method of low cost. Inside this investigation work was found that depending on the microorganism type, it varies the quantity of cupric zeolite that is required to carry out the water disinfection, being great for the case of yeasts than the bacteria s. In addition to that marked differences are presented in the required time to reach this process. The characterization of the natural zeolite material, sodium and cupric, was realized by means of scanning electron microscopy, determining the elementary composition (Energy Dispersive Spectroscopy) of each one of them, and by X-ray diffraction. (Author)

  1. Natural zeolites: characteristic, properties and uses

    International Nuclear Information System (INIS)

    Bosch, P.; Bulbulian, S.; Olguin, M. T.

    2011-01-01

    The zeolites are a crystalline aluminium silicates family of volcanic origin. It characterizes them a porous structure, nano metric, regular and homogeneous. Therefore, they turn out to be excellent molecular sieves besides exchangers of ions. This last property it has been extremely exploited, in order to retain the radioactive ions of the contaminated waters in the accident of Three Mile Island (USA), of Chernobyl (Russia) and Fukushima Daiichi (Japan). Nevertheless, the use of the zeolites goes but there ... these they can work as much as nutritional supplement for chickens and pigs, as well as for to retain odors or to separate gases. The construction industry has welcomed this mineral, when either using it as quarry or additive in the called pozzolanic cements. In this book the authors explain the zeolites formation in the nature, their structure and the main uses of these minerals that some authors have baptized as the magic rocks. (Author)

  2. Thermal Analysis of Lampung Zeolite as Ion Cesium Replacement

    International Nuclear Information System (INIS)

    Aslina-Br-Ginting; Dian-Anggraini; Arif-Nugroho

    2007-01-01

    Zeolite have the cation can move freely and as exchangeable partly or totally with other cations. Therefore, it can serve the purpose of ion exchanger very selectively to ion cesium which is present in fuel waste. In this research analysis of pore surface area, radius pore, and adsorption have been done. After the characters of Lampung zeolite is known and then analysis of cation exchange capacity (CEC) toward ion 137 Cs is conducted, analysis of Lampung zeolite adsorption to ion 137 Cs in waste of fissile product and in research waste is subsequently done. Result of analysis show Lampung zeolite has surface area of 10,0478 m 2 , specific surface area of 47,0841 m 2 /g, pore radius of 19,3020 o A and adsorption of 24,500 cc/g. For application as a ion exchange, Lampung zeolite can adsorb ion 137 Cs reaching maximum at concentration of CsCl 0,5 N with the contact time 1 day and the optimum KTK value is 0,8360 m eq/g. While Lampung zeolite is able to adsorb 86,4 % ion Cs in waste of fission product. (author)

  3. Decomposição do NO sobre Cu suportado em zeólitas

    Directory of Open Access Journals (Sweden)

    Oliveira Andréa Marins de

    2004-01-01

    Full Text Available Direct decomposition of NO on copper supported on zeolite catalysts such as MCM-22 and Beta was compared with that on the thoroughly studied Cu-ZSM-5. The catalysts were prepared by ion-exchange in basic media. They were characterized by atomic absorption, surface area, nitrogen adsorption at 77K, X-ray diffraction and temperature programmed reduction. The products of the reaction were analyzed by Fourier transform infrared spectroscopy using a gas cell. Catalytic activity tests indicated that zeolite catalysts, like Beta and MCM-22, lead to NO conversion values comparable to ZSM-5.

  4. Acidity in zeolite catalysis

    NARCIS (Netherlands)

    Santen, van R.A.; Gauw, de F.J.M.M.; Corma, A.; Melo, F.; Mendioroz, S.; Fierro, J.L.G.

    2000-01-01

    A review with 21 refs. is provided on our current understanding of the activation of hydrocarbons by protonic zeolites. One has to distinguish the proton affinity of a zeolite, measured in an equil. expt., from proton activation that dets. a kinetic catalytic result. The proton affinity depends on

  5. Zeolite ZSM-57

    International Nuclear Information System (INIS)

    Valyocsik, E.W.; Page, N.M.; Chu, C.T.W.

    1989-01-01

    This patent describes a synthetic porous crystalline zeolite having a molar ratio of XO 2 ; Y 2 O 3 of at least 4. Wherein X represents silicon and/or germanium and Y represents aluminum, boron, chromium, iron and/or gallium. The porous crystalline zeolite having at least the X-ray diffraction lines as set forth in the text

  6. Utilization of Zeolites in environmentally protection

    Energy Technology Data Exchange (ETDEWEB)

    Kallo, D. [Hungarian Academy of Sciences, Chemical Research Center, Institute of Chemistry, Budapest (Hungary)

    2000-07-01

    It has been attempted to present the most important fields of natural zeolite applications in environmental protection. Realized and approved utilizations were demonstrated inciting the reader to take these materials into consideration for solution of similar problems. The outlined properties can be used for other purposes not discussed in this review. They can be applied, e.g., in fish farming, transportation of living fishes when simultaneous ammonium and carbon dioxide removals is required: ammonium is exchanged for calcium present in the zeolite and CO{sub 2} is then precipitated in the form of CaCO{sub 3}; in treatment of diluted manure when undesired organics can be fixed and bactericide effects can be attained. Natural zeolites are used, therefore, as deodorant of litter of dogs or cats. Small amounts of metal cations, e.g., Cu{sup 2+}, Ag{sup +} or Zn{sup 2+}, introduced by ion exchange may disinfect contacting water. Due to water adsorption and desorption capability natural zeolite as construction materials exert some conditioning effect without any mechanical accessory. It seems likely the human ingenuity will continue to discover new applications in the future.

  7. Zeolites applications in pollution control; radioactive-, municipal-, industrial- and agricultural-waste water treatments: part-I

    International Nuclear Information System (INIS)

    Akbar, S.

    1991-01-01

    Zeolite cations exchangers provide a unique combination of selectivity, capacity and stability not available in other ion-exchangers. In this era of environmental concern, the attractive physical and chemical properties of zeolites have been utilized worldwide in the solution to this problem. The desirable characteristics of high ion-exchange selectivity and resistance to radiolytic degradation have made certain zeolites quite useful for the separation and purification of radioisotopes from radioactive wastewater. Zeolites have also been effectively used in nuclear industry for treatment of radioactive wastes and selectively removing ammonium ions from wastewater. (author)

  8. Investigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons

    KAUST Repository

    Liu, Zhaohui

    2015-08-26

    Hierarchically porous zeolite Beta (Beta-MS) synthesized by a soft-templating method contains remarkable intra-crystalline mesoporosity, which reduces the diffusion length in zeolite channels down to several nanometers and alters the distribution of Al among distinct crystallographic sites. When used as a catalyst for the conversion of methanol to hydrocarbons (MTH) at 330 oC, Beta-MS exhibited a 2.7-fold larger conversion capacity, a 2.0-fold faster reaction rate, and a remarkably longer lifetime than conventional zeolite Beta (Beta-C). The superior catalytic performance of Beta-MS is attributed to its hierarchical structure, which offers full accessibility to all catalytic active sites. In contrast, Beta-C was easily deactivated because a layer of coke quickly deposited on the outer surfaces of the catalyst crystals, impeding access to interior active sites. This difference is clearly demonstrated by using electron microscopy combined with electron energy loss spectroscopy to probe the distribution of coke in the deactivated catalysts. At both low and high conversions, ranging from 20% to 100%, Beta-MS gave higher selectivity towards higher aliphatics (C4-C7) but lower ethene selectivity compared to Beta-C. Therefore, we conclude that a hierarchical structure decreases the residence time of methylbenzenes in zeolite micropores, disfavoring the propagation of the aromatic-based catalytic cycle. This conclusion is consistent with a recent report on ZSM-5 and is also strongly supported by our analysis of soluble coke species residing in the catalysts. Moreover, we identified an oxygen-containing compound, 4-methyl-benzaldehyde, in the coke, which has not been observed in the MTH reaction before.  

  9. Investigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons

    KAUST Repository

    Liu, Zhaohui; Dong, Xinglong; Zhu, Yihan; Emwas, Abdul-Hamid M.; Zhang, Daliang; Tian, Qiwei; Han, Yu

    2015-01-01

    Hierarchically porous zeolite Beta (Beta-MS) synthesized by a soft-templating method contains remarkable intra-crystalline mesoporosity, which reduces the diffusion length in zeolite channels down to several nanometers and alters the distribution of Al among distinct crystallographic sites. When used as a catalyst for the conversion of methanol to hydrocarbons (MTH) at 330 oC, Beta-MS exhibited a 2.7-fold larger conversion capacity, a 2.0-fold faster reaction rate, and a remarkably longer lifetime than conventional zeolite Beta (Beta-C). The superior catalytic performance of Beta-MS is attributed to its hierarchical structure, which offers full accessibility to all catalytic active sites. In contrast, Beta-C was easily deactivated because a layer of coke quickly deposited on the outer surfaces of the catalyst crystals, impeding access to interior active sites. This difference is clearly demonstrated by using electron microscopy combined with electron energy loss spectroscopy to probe the distribution of coke in the deactivated catalysts. At both low and high conversions, ranging from 20% to 100%, Beta-MS gave higher selectivity towards higher aliphatics (C4-C7) but lower ethene selectivity compared to Beta-C. Therefore, we conclude that a hierarchical structure decreases the residence time of methylbenzenes in zeolite micropores, disfavoring the propagation of the aromatic-based catalytic cycle. This conclusion is consistent with a recent report on ZSM-5 and is also strongly supported by our analysis of soluble coke species residing in the catalysts. Moreover, we identified an oxygen-containing compound, 4-methyl-benzaldehyde, in the coke, which has not been observed in the MTH reaction before.  

  10. The vibrational dynamics of carbon monoxide in a confined space-CO in zeolites.

    Science.gov (United States)

    Nachtigallová, Dana; Bludský, Ota; Otero Areán, Carlos; Bulánek, Roman; Nachtigall, Petr

    2006-11-14

    Based on theoretical calculations, and a survey of infrared spectra of CO adsorbed on different cation exchanged zeolites, a model is proposed to explain the influence of the zeolite framework on the vibrational behaviour of CO confined into small void spaces (zeolite channels and cavities). The concepts developed should help to understand a number of details relevant to both, precise interpretation of IR spectra and a better understanding of the vibrational dynamics of small molecules in a confined space.

  11. Highly selective oxidation of styrene to benzaldehyde over a tailor-made cobalt oxide encapsulated zeolite catalyst.

    Science.gov (United States)

    Liu, Jiangyong; Wang, Zihao; Jian, Panming; Jian, Ruiqi

    2018-05-01

    A tailor-made catalyst with cobalt oxide particles encapsulated into ZSM-5 zeolites (Co 3 O 4 @HZSM-5) was prepared via a hydrothermal method with the conventional impregnated Co 3 O 4 /SiO 2 catalyst as the precursor and Si source. Various characterization results show that the Co 3 O 4 @HZSM-5 catalyst has well-organized structure with Co 3 O 4 particles compatibly encapsulated in the zeolite crystals. The Co 3 O 4 @HZSM-5 catalyst was employed as an efficient catalyst for the selective oxidation of styrene to benzaldehyde with hydrogen peroxide as a green and economic oxidant. The effect of various reaction conditions including reaction time, reaction temperature, different kinds of solvents, styrene/H 2 O 2 molar ratio and catalyst dosage on the catalytic performance were systematically investigated. Under the optimized reaction condition, the yield of benzaldehyde can achieve 78.9% with 96.8% styrene conversion and 81.5% benzaldehyde selectivity. Such an excellent catalytic performance can be attributed to the synergistic effect between the confined reaction environment and the proper acidic property. In addition, the reaction mechanism with Co 3 O 4 @HZSM-5 as the catalyst for the selective oxidation of styrene to benzaldehyde was reasonably proposed. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Isobutane/2-butene alkylation with zeolite Y without BrÆnsted acidity

    OpenAIRE

    Rosenbach Jr, Nilton; Mota, Claudio J. A.

    2005-01-01

    Alkylation of isobutane with 2-butene was performed on metal-exchanged Y zeolites, using an alkylchloride as carbocation initiator. The results indicated that, compared with a protonic zeolite, the deactivation was significantly slower and the production of trimethylpentanes was higher on the metal-exchanged zeolites. The metal cations act as Lewis acids, interacting with the chloride initiating the carbocationic reactions. The results also support the view that protonic sites on the catalyst...

  13. Two crystal structures of Ag sup + -and Tl sup + -exchanged zeolite X, Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X

    CERN Document Server

    Kim, S Y; Kim, Y

    2002-01-01

    Two crystal structures of dehydrated Ag sup + -and Tl sup + -exchanged zeolite X (Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) .deg. C (a = 24.758(4) A, a = 24.947(4) A, respectively). Their structures were refined to the final error indices R sub 1 = 0.055 and wR sub 2 = 0.057 with 375 reflections, and R sub 1 = 0.058 and wR sub 2 = 0.057 with 235 reflections, respectively, for which I> 3 sigma(I). In the structure of Ag sub 2 sub 7 Tl sub 6 sub 5 -X, 27 Ag sup + ions were found at two crystallographic sites: 15 Ag sup + ions at site I at the center of the hexagonal prism and the remaining 12 Ag sup + ions at site II' in the sodalite cavity. Sixty-five Tl sup + ions were located at three crystallographic sites: 20 Tl sup + ions at site II opposite single six-rings in the supercage, 18 Tl sup + ions at site I' in the sodalite cavity opposite the D6Rs, and the remaining 27 Tl sup ...

  14. Hydrothermally grown zeolite crystals

    International Nuclear Information System (INIS)

    Durrani, S.K.; Qureshi, A.H.; Hussain, M.A.; Qazi, N.K.

    2009-01-01

    The aluminium-deficient and ferrosilicate zeolite-type materials were synthesized by hydrothermal process at 150-170 degree C for various periods of time from the mixtures containing colloidal reactive silica, sodium aluminate, sodium hydroxide, iron nitrate and organic templates. Organic polycation templates were used as zeolite crystal shape modifiers to enhance relative growth rates. The template was almost completely removed from the zeolite specimens by calcination at 550 degree C for 8h in air. Simultaneous thermogravimetric (TG) and differential thermal analysis (DTA) was performed to study the removal of water molecules and the amount of organic template cations occluded inside the crystal pore of zeolite framework. The 12-13% weight loss in the range of (140-560 degree C) was associated with removal of the (C/sub 3/H/sub 7/)/sub 4/ N+ cation and water molecules. X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) techniques were employed to study the structure, morphology and surface features of hydrothermally grown aluminium-deficient and ferrosilicate zeolite-type crystals. In order to elucidate the mode of zeolite crystallization the crystallinity and unit cell parameters of the materials were determined by XRD, which are the function of Al and Fe contents of zeolites. (author)

  15. Design and characterization of chitosan/zeolite composite films — Effect of zeolite type and zeolite dose on the film properties

    International Nuclear Information System (INIS)

    Barbosa, Gustavo P.; Debone, Henrique S.; Severino, Patrícia; Souto, Eliana B.; Silva, Classius F. da

    2016-01-01

    Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance. - Highlights: • Zeolite/chitosan composite films were prepared by casting technique. • Micrographs showed slight difference according to the content and A-type zeolite. • The barrier properties of the films were suitable to the dressing application. • Film characterization suggested that zeolites interacted with the chitosan chain.

  16. Design and characterization of chitosan/zeolite composite films — Effect of zeolite type and zeolite dose on the film properties

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Gustavo P.; Debone, Henrique S. [Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema (Brazil); Severino, Patrícia [Universidade Tiradentes, Instituto de Tecnologia e Pesquisa, Aracaju (Brazil); Souto, Eliana B. [Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra (Portugal); Center for Neuroscience and Cell Biology & Institute for Biomedical Imaging and Life Sciences (CNC-IBILI), University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra (Portugal); Silva, Classius F. da, E-mail: cfsilva@unifesp.br [Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema (Brazil)

    2016-03-01

    Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance. - Highlights: • Zeolite/chitosan composite films were prepared by casting technique. • Micrographs showed slight difference according to the content and A-type zeolite. • The barrier properties of the films were suitable to the dressing application. • Film characterization suggested that zeolites interacted with the chitosan chain.

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

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro, Serguei [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco (Chile); Valdés, Héctor, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Manéro, Marie-Hélène [Université de Toulouse (France); INPT, UPS (France); Laboratoire de Génie Chimique, 4, Allée Emile Monso, F–31030 Toulouse (France); CNRS (France); Laboratoire de Génie Chimique, F–31030 Toulouse (France); Zaror, Claudio A. [Departamento de Ingeniería Química (F. Ingeniería), Universidad de Concepción, Concepción, Correo 3, Casilla 160–C (Chile)

    2014-06-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: 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 823 K 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 623 K, 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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: 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 823 K 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 623 K, 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

  19. Local Environment and Nature of Cu Active Sites in Zeolite-Based Catalysts for the Selective Catalytic Reduction of NOx

    NARCIS (Netherlands)

    Deka, U.|info:eu-repo/dai/nl/325811202; Lezcano-Gonzalez, I.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Beale, A.M.|info:eu-repo/dai/nl/325802068

    2013-01-01

    Cu-exchanged zeolites have demonstrated widespread use as catalyst materials in the abatement of NOx, especially from mobile sources. Recent studies focusing on Cu-exchanged zeolites with the CHA structure have demonstrated them to be excellent catalysts in the ammonia-assisted selective catalytic

  20. Introduction to chemistry of crystalline zeolites and its applications

    International Nuclear Information System (INIS)

    Lobo Cabezas, Raul Francisco

    2006-01-01

    Establishes the zeolites as the most important group of solid acids and its relation to the contemporaneous chemical industry. It describes that zeolites are used in the following applications: refineries, chemicals/petrochemicals, environmental chemistry, separation of gas, adsorbent ia and ionic exchange in water purification in mineral processes, medicine and agricultural industry. Zeolites are defined as crystalline aluminium silicates with a compound structure of interconnected tetrahedrons. It mentions the key components in zeolites structure. It focuses that structural basic unity of the zeolite is the tetrahedron and compound structural unities are: cells and columns. Besides, it describes that pore system defines a lot of all its properties; but chemical composition affects them. Composition and properties of zeolites are established: adsorption, molecular sieves, acidity, selectivity, transition state in the hydrocarbon's chemistry. It concludes that the newer application of zeolite is in oxidations: Titanium-Silicate-1; production of propylene's oxide using peroxide of hydrogen as oxidizing. The catalysis is an active area of research, and the most popular areas are related to chemicals and the environment [es