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Zeolite Catalysts (zeolite + catalyst)
Selected AbstractsSelective Petroleum Refining Over a Zeolite Catalyst with Small Intracrystal Mesopores,ANGEWANDTE CHEMIE, Issue 41 2009Ho Park Prof. Vom Zeolith zerkleinert: Mesoporöse ZSM-5-Zeolithkatalysatoren (siehe TEM-Bild), die mithilfe weicher Template erhalten wurden, weisen höhere Aktivitäten für das Cracken von Gasöl und bessere Produktselektivitäten als übliches ZSM-5 auf. Große Kohlenwasserstoffe werden in den Mesoporen der Kristalle in Benzin- und Dieselmoleküle gespalten, die Umwandlung kleinerer Moleküle in Olefine findet in den Mikroporen des Netzwerks statt. [source] Synthesis of ,-Amino Alcohols from Aromatic Amines and Alkylene Carbonates Using Na-Y Zeolite Catalyst.CHEMINFORM, Issue 40 2006Anandkumar B. Shivarkar Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Hierarchical Zeolite Catalysts: Zeolite Catalysts with Tunable Hierarchy Factor by Pore-Growth Moderators (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Mater. On page 3972, Pérez-Ramírez et al. introduce the hierarchy factor as a valuable descriptor to categorize hierarchical zeolites and to optimize their design for catalytic applications. They demonstrate a direct correlation between the catalytic performance of ZSM-5 in benzene alkylation and the hierarchy factor. Maximization of the hierarchy factor is achieved by enhancing the mesopore surface area without reducing the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment in the presence of pore growth moderators (quaternary ammonium cations) is presented. [source] Zeolite Catalysts with Tunable Hierarchy Factor by Pore-Growth ModeratorsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Javier Pérez-Ramírez Abstract The design of hierarchical zeolite catalysts is attempted through the maximization of the hierarchy factor (HF); that is, by enhancing the mesopore surface area without severe penalization of the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment of ZSM-5 in the presence of quaternary ammonium cations is developed. The organic cation (TPA+ or TBA+) acts as a pore-growth moderator in the crystal by OH, -assisted silicon extraction, largely protecting the zeolite crystal during the demetallation process. The protective effect is not seen when using cations that are able to enter the micropores, such as TMA+ Engineering the pore structure at the micro- and mesolevel is essential to optimize transport properties and catalytic performance, as demonstrated in the benzene alkylation with ethylene, a representative mass-transfer limited reaction. The hierarchy factor is an appropriate tool to classify hierarchically structured materials. The latter point is of wide interest to the scientific community as it not only embraces mesoporous zeolites obtained by desilication methods but it also enables to quantitatively compare and correlate various materials obtained by different synthetic methodologies. [source] One-Step Preparation of 1-Substituted Tetrahydroisoquinolines via the Pictet,Spengler Reaction Using Zeolite Catalysts.CHEMINFORM, Issue 7 2005Adrienn Hegedues Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of 2-Substituted Indoles by Palladium-Catalyzed Heteroannulation with Pd,NaY Zeolite Catalysts.CHEMINFORM, Issue 18 2004Ki Bum Hong Abstract For Abstract see ChemInform Abstract in Full Text. [source] Catalytic Combustion of Ethyl Acetate over Nanostructure Cobalt Supported ZSM-5 Zeolite CatalystsCHINESE JOURNAL OF CHEMISTRY, Issue 3 2009Aligholi NIAEI Abstract Gas phase catalytic combustion of ethyl acetate, as one of volatile organic compounds (VOC), was studied on nanostructure ZSM-5, HZSM-5 and Co-ZSM-5 with different cobalt loadings. Nanostructure of ZSM-5 was determined by XRD, SEM and TEM. Catalytic studies were carried out under atmospheric pressure in a fixed bed reactor. Results showed that the Co-ZSM-5 catalysts had better activity than others and at temperatures below 350 °C, amount of Co loading was more effective on catalytic activity. The order of conversion of ethyl acetate over different Co loading is as follows: Co-ZSM-5 (0.75 wt%) Enhancing the Porosity of Mesoporous Carbon-Templated ZSM-5 by DesilicationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2008Martin S. Holm Abstract A tunable desilication protocol applied on a mesoporous ZSM-5 zeolite synthesized by carbon-templating is reported. The strategy enables a systematic manufacture of zeolite catalysts with moderate to very high mesoporosities. Coupling carbon-templating and desilication thus allow for more than a doubling of the original mesopore volume and mesopore surface area. The porosity effect arising from various treatment times and base amounts in the media has beenthoroughly mapped. Initially, small mesopores are created, and as desilication strength increases the average mesopore size enhances. Crystallinity of the treated samples is retained, and electron microscopy indicates solely intracrystalline mesoporosity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Zeolite Catalysts with Tunable Hierarchy Factor by Pore-Growth ModeratorsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Javier Pérez-Ramírez Abstract The design of hierarchical zeolite catalysts is attempted through the maximization of the hierarchy factor (HF); that is, by enhancing the mesopore surface area without severe penalization of the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment of ZSM-5 in the presence of quaternary ammonium cations is developed. The organic cation (TPA+ or TBA+) acts as a pore-growth moderator in the crystal by OH, -assisted silicon extraction, largely protecting the zeolite crystal during the demetallation process. The protective effect is not seen when using cations that are able to enter the micropores, such as TMA+ Engineering the pore structure at the micro- and mesolevel is essential to optimize transport properties and catalytic performance, as demonstrated in the benzene alkylation with ethylene, a representative mass-transfer limited reaction. The hierarchy factor is an appropriate tool to classify hierarchically structured materials. The latter point is of wide interest to the scientific community as it not only embraces mesoporous zeolites obtained by desilication methods but it also enables to quantitatively compare and correlate various materials obtained by different synthetic methodologies. [source] Investigation into the potential of a novel superacid catalyst for the catalytic upgrading of pyrolytic bio-oilINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2003Natalie G. Wilson Abstract Treatment of zirconium oxide with sulphate ions forms a highly acidic, or superacidic catalyst; sulphated zirconia. This catalyst has been found previously to be highly applicable to a range of reactions including acylation alkylation, isomerization, cracking and dehydration at temperatures in the range 150,200°C. These relatively low-temperature reactions offer potential in the field of bio-oil catalytic upgrading. Here zeolite catalysts have been used predominantly, but with associated problems due to the high reaction temperatures related with their use. The paper describes the processes involved in optimization of a process for the catalytic upgrading of a bio-oil produced by slow pyrolysis of pine wood. Copyright © 2002 John Wiley & Sons, Ltd. [source] Kinetic modeling of catalytic conversion of methylcyclohexane over USY zeolites: Adsorption and reaction phenomenaAICHE JOURNAL, Issue 6 2009Mustafa Al-Sabawi Abstract Catalytic conversion of cycloparaffins is a complex process involving competing reaction steps. To understand this process, FCC experiments using methylcyclohexane (MCH) on USY zeolite catalysts were carried out in the mini-fluidized CREC riser simulator. Runs were developed under relevant FCC process conditions in terms of partial pressures of MCH, temperatures (450,550°C), contact times (3,7 s), catalyst-oil mass ratios (5), and using fluidized catalysts. MCH overall conversions ranged between 4 to 16 wt %, with slightly higher conversions obtained using the larger zeolite crystallites. Moreover, it was found that MCH undergoes ring opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. A heterogeneous kinetic model for MCH conversion including thermal effects, adsorption and intrinsic catalytic reaction phenomena was established. Adsorption and kinetic parameters were determined, including the heat of adsorption (,40 kJ/mol), as well as thermal and primary catalytic intrinsic activation energies, which were in the range of 43,69 kJ/mol, and 50,74 kJ/mol, respectively. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Efficient Synthesis of Dimethyl Ether over HZSM-5 Supported on Medium-Surface-Area ,-SiC FoamCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 10 2008Svetlana Ivanova Dr. Abstract In this study, we aimed to produce a highly selective and stable catalyst for the production of dimethyl ether by methanol dehydration. The activities were compared of different active phases of the employed system, zeolite HZSM-5 or , -alumina, supported on silicon carbide as foam, and it was found that the supported zeolite catalysts are more active than and as selective as the alumina-based catalysts. The as-prepared zeolite/SiC composites reveal good stability in long-term tests in the presence or absence of steam. The high stability is attributed to the presence of highly dispersed micrometer-sized zeolite particles, which make the active sites more accessible to the reactants and promote the quick transfer of the desired product, dimethyl ether, out of the catalyst bed, minimizing deactivation of the catalyst. [source]
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