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...

identification of homogenous watershed sub basins allows generalization of environmental study results. for this purpose, first available data for 27 selected watersheds in north alborz regarding 21 variables including physiographic and climatic characteristics was gathered. the most important factors impacting upon soil erosion and sediment yield were equivalent rectangular length, mean annual...

highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefins such as norbornene (n) or of copolymerizing them with ethene (e) or propene (p). the polymers obtained show exciting structures and properties. e-n copolymers are industrially produced materials, with variable and high glass transitions depending on the wide range of their micr...

fischer-tropsch catalysts with high activity and selectivity for olefins were produced using mordenite type sio2/al2o3= 12, 20, 28, 62 zeolite supported iron carbonyl compounds and were characterized by x-ray powder diffraction. the adsorptionof volatile fe(co)5 on the support surface was carried out under vacuum at room temperature. reduction les were monitored by vibrating sample magnetometer...

The aim within this project was to optimise the CO oxidation over TiO2 supported gold catalysts, focusing on two different preparation methods; deposition precipitation (DP) and photodeposition (PD), using different types of TiO2 and varying the theoretical gold loading. The catalyst were characterised with TEM (size) and ICP-AES (loading). For DP catalysts, the support is important for high ac...

bioleaching of spent refinery processing catalysts using adapted indigenous strains ofacidithiobacillus ferrooxidans to recover ni and mo, and the separation of ni from bioleaching liquor usingiron magnetic nanoparticles were optimized in this study. bioleaching optimization was performed usingcentral composite design (ccd) method to optimize temperature (32 to 38oc), initial ph (1.5 to 2), par...

in this study we have tested the ability of a standard dft computational protocol to reproduce the experimentally obtained stereoselectivity of 26 different c2-symmetric zirconocene catalysts active in propylene polymerization. the catalysts were chosen for their relevance in metallocene catalyzed polymerization of propylene. to this end, primary insertion of both si- and re-propylene enantiofa...

beside ziegler-natta and phillips catalysts the development of methylaluminoxane (mao) as cocatalyst incombination with metallocenes or other transition metal complexes for the polymerization of olefins haswidely increased the possibilities in controlling the polymer composition, polymer structure, tacticity and special properties with high precision. these catalysts allow the synthesis of isot...