نتایج جستجو برای: zsm 12
تعداد نتایج: 582456 فیلتر نتایج به سال:
Fe2O3/ZSM-5 modified with Ce via citrate route (sol-gel approach) is applied for H2S removal in 500–700 ◦C temperature range. The sulfidation activity of Fe2O3/ZSM-5 is appreciably promoted by introduction of Ce plausibly attributed to the synergy of Fe2O3 and CeO2. 5Fe5Ce/ZSM-5 performs the optimal desulfurization behavior at 600 ◦C with sulfur capacity of 1020 μmol S/g, and the sulfidation pr...
Fe/ZSM-5 nanosheet zeolites of varying thickness were synthesized with di- and tetraquaternary ammonium structure directing agents and extensively characterized for their textural, structural, and catalytic properties. Introduction of Fe3+ ions in the framework of nanosheet zeolites was slightly less effective than in bulk ZSM-5 zeolite. Steaming was necessary to activate all catalysts for N2O ...
Aluminum coordination in the framework of USY and ZSM-5 zeolites containing charge-compensating cations (NH4+, H+, or Cu+) was investigated by Al K-edge EXAFS and XANES. This work was performed using a newly developed in-situ cell designed especially for acquiring soft X-ray absorption data. Both tetrahedrally and octahedrally coordinated Al were observed for hydrated H-USY and H-ZSM-5, in good...
Subtle structural details of siliceous zeolites are probed by using two-bond scalar (J) coupling constants to characterize covalently bonded 29Si-O-29Si site pairs and local framework order. Solid-state two-dimensional (2D) 29Si{29Si} NMR measurements and first-principles calculations of 2J(29Si-O-29Si) couplings shed insights on both the local structures of siliceous zeolites Sigma-2 and ZSM-1...
Interpretation of catalytic performance during the MTH process is hampered by heat transport phenomena. We demonstrate that large temperature rises can occur during fixed bed labscale catalyst testing of ZSM-5, even when a large catalyst bed dilution is applied. Formation of mesopores in ZSM-5 leads to partial mitigation of these effects because of a lower generation of heat per unit catalyst v...
Microspectroscopic methods were explored to investigate binder effects occurring in ZSM-5-containing SiO2- and Al2O3-bound millimetre-sized extrudates. Using thiophene as a selective probe for Brønsted acidity, coupled with time-resolved in situ UV/Vis and confocal fluorescence microspectroscopy, variations in reactivity and selectivity between the two distinct binder types were established. It...
The influence of a highly oxygenated, polar protic reaction medium, that is, levulinic acid in 2-ethylhexanoic acid, on the dealumination of two zeolite-supported ruthenium catalysts, namely Ru/H-β and Ru/H-ZSM-5, has been investigated by 27 Al triple-quantum magic-angle spinning nuclear magnetic resonance spectroscopy (3QMAS NMR). Upon use of these catalysts in the hydrogenation of levulinic a...
The adsorption and desorption of N2O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out to determine the desorbed temperature Tmax corresponding to the maximum mass intensity of N2O desorption peak and adsorption capacity of N2O on metal-ion-exchanged ZSM-5s. The results i...
A new catalyst comprising cerium and silver ion-exchanged ZSM-5 zeolite is reported in this paper, for the reduction of nitric oxide by methane in the presence of excess oxygen. The bi-cation exchanged Ce-Ag-ZSM-5 catalyst was very active for this reaction, while either Ce-ZSM-5 or Ag-ZSM-5 alone showed low activity. The presence of oxygen in the feed gas mixture enhanced the activity of the ca...
Kaolin with alumina and silica content is used as the main material in this research to study synthesis of ZSM-5 zeolite. The hydrothermal process was carried out through different aging times, namely 12, 24 36 hours. Tetrapropyl ammonium bromide (TPABr) a template for Mobile Five-1 (MFI) structure guide. X-ray diffraction (XRD) infrared spectroscopy (FTIR) instruments were characterize zeolite...
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