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...

accelerated deactivation of co/al2o3 catalysts in fischer-tropsch synthesis and the effect of re and ru as the catalytic promoters are reported. 15wt% co/al2o3 catalyst and 1wt% ru and 1.4wt% re  promoted cobalt catalysts have been formulated and extensively characterized. the deactivation of the unpromoted cobalt catalyst and those promoted with re and ru were studied by accelerated method at ...

Metallic nanoparticles are emerging as an exciting class of heterogeneous catalysts with the potential advantages of exceptional activity, stability, recyclability, and easier separation than homogeneous catalysts. The traditional colloid nanoparticle syntheses usually involve strong surface binding ligands that could passivate the surface active sites and result in poor catalytic activity. The...

The Grubbs' first and second generation catalysts were occluded into cross-linked slabs of polydimethylsiloxane with volumes from 1 mm3 to 1 cm3 by swelling the polymer with catalyst and methylene chloride. Methylene chloride was evaporated under vacuum to yield occluded catalysts where their solvent was polydimethylsiloxane. These occluded catalysts were reacted with alkenes dissolved in H2O o...

Increased oxygen reduction reaction (ORR) kinetics, improved CO tolerance, and more efficient water and heat management represent significant advantages that high-temperature polymer electrolyte fuel cells (HT-PEFCs) operating with a phosphoric acid-doped polybenzimidazole (PBI) membrane offer over traditional Nafion-based, low-temperature PEFCs. However, before such HT-PEFCs become viable, the...

Selective catalytic reduction (SCR) with NH3 is the most efficient and economic flue gas denitrification technology developed to date. Due to its high low-temperature catalytic activity, Mn-based catalysts present a great prospect for application in SCR de-NOx at low temperatures. However, overcoming the poor resistance of Mn-based catalysts to H2O and SO2 poison is still a challenge. This pape...