نتایج جستجو برای: reuseable catalysts
تعداد نتایج: 32969 فیلتر نتایج به سال:
In this study, the nanoporous γ-alumina catalysts were prepared by the sol-gel method using hydrolysis of aluminum isopropoxide in the presence of TX-100 or gelatin/TX-100 mixture. Catalysts were characterized by XRD, FT-IR, TEM, BET-BJH and N2 adsorption-desorption isotherms. To investigate reactivity and selectivity of the synthesized catalysts, dehydration reaction of 2-octanol was carried o...
Received: 15 December 2004; Revised: 26 January 2005 Abstract Copper zinc oxide catalysts prepared similar to industrially used catalysts were studied by high-resolution electron microscopy. The microstructure of the Cu/ZnO catalysts deviates considerably from that of bulk copper metal and idealized copper model systems. In order to reveal reliable structure-activity relationships for copper ca...
Copper-manganese oxide catalysts are prepared with an atomic ratio of Cu/Mn=2/1 using a coprecipitation procedure under air atmosphere. The time of aging, i.e., the time that precipitate remains in contact with the precipitating medium, has been varied from 0 (for unaged precursor) to 300 minutes and the effect of precipitate aging time in each atmosphere upon the structure and morphology of di...
Using MeN=CMe(2) as an imine model, computational chemistry has been applied to design metal-free hydrogenation catalysts. The implementation includes designing proper electronic structures to split H(2) and building appropriate chemical scaffolds to prevent possible side reactions which may deactivate the catalysts. Interestingly, the designed catalysts bear resemblances to the well-known meta...
Atomically dispersed catalysts refer to substrate-supported heterogeneous catalysts featuring one or a few active metal atoms that are separated from one another. They represent an important class of materials ranging from single-atom catalysts (SACs) and nanoparticles (NPs). While SACs and NPs have been extensively reported, catalysts featuring a few atoms with well-defined structures are poor...
In contrast to solid acid catalysts, much fewer efforts have been made to study solid base catalysts. In this thesis, preparation, characterization and application of oxides and modified oxide as solid base catalysts were studied. The catalysts include MgO prepared by different methods, potassium-modified ZrO2, calcined Mg-Al hydrotalcites, and a novel catalyst system Mg(O,F), which was prepare...
the series of mono-metallic and bi-metallic catalysts have been prepared by impregnatingwith solutions containing compound of h2ptc15,nbc15 and lml hc1 (0.1 mol). the activityand selectivity of the catalysts have been determined under conditions at 450-500°c, 15-30atm. molar ratio h2/c7h16=5 and vvh=1.5/h for converting n-heptane. under theseexperimental conditions it has been established that ...
Cyanide leaching was used to obtain Au/SiO2 catalysts with very low gold loadings. A number of catalysts with a nominal 5 wt% target loading were prepared using impregnation and deposition precipitation techniques and these were found to be active catalysts for the solvent-free aerobic oxidation of benzyl alcohol. Exposure of these catalysts to a basic solution of NaCN for 10 min leached gold f...
In this research different types of Al2O3 were used as supports to prepare catalysts for dehydrogenation of isobutane to isobutene. These supports were Al2O3 from Merck, Axen and gamma Al2O3 synthesized from Al(OH)3. Sn/Pt/Al2O3 catalysts were prepared by sequential impregnation, at first Pt and then Sn was deposited. Characterization of catalysts was performed by X-ray powder diffraction (XRD)...
Microporous carbon catalysts with large surface areas (800-1100 m(2) g(-1)) and high densities of SO3H groups (ca. 1.1 mmol g(-1)) were synthesized by sulfonation of zeolite-templated microporous carbon. The resulting SO3H-bearing microporous carbon catalysts exhibited higher catalytic performance for the hydrolysis of cellobiose and the Beckmann rearrangement than conventional solid acid catal...
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