The original model of P systems with symbol objects introduced by Păun was shown to be computationally universal, provided that catalysts and priorities of rules are used. By reduction via register machines Sosík and Freund proved that the priorities may be omitted from the model without loss of computational power. Freund, Oswald, and Sosík considered several variants of P systems with catalys...

The vapour phase selective conversion of glycerol to acetol at normal atmospheric pressure in a fixed-bed micro reactor was investigated over SO4 2 and WOx promoted ZrO2 and M-ZrO2 (M = Al2O3 or TiO2) solid acid catalysts. The investigated sulfate and tungstate ion promoted zirconia-based catalysts were prepared by both coprecipitation and impregnation methods and calcined at 923 K. The synthes...

This article reviews the surface science of the heterogeneous olefin polymerization catalysts. The specific focus is on how to prepare and characterize stereochemically specific heterogeneous model catalysts for the Ziegler-Natta polymerization. Under clean, ultra-high vacuum conditions, low-energy electron irradiation during the chemical vapor deposition of model Ziegler-Natta catalysts can be...

Heterogeneous catalysts are now being tried extensively for biodiesel synthesis. These catalysts are poised to play an important role and are perspective catalysts in future for biodiesel production at industrial level. The review deals with a comprehensive list of these heterogeneous catalysts which has been reported recently. The mechanisms of these catalysts in the transesterification reacti...

Cu+l(Si02/A1203), Cu+/A1203 and Cu+/Si02 catalysts were prepared by a combination of the ion-exchange method and thermovacuum treatment. In-situ XANES and EXAFS investigations of the catalysts have revealed that Cu+ ions are anchored onto Alz03 or SiO2 as planar 3-coordinate Cu+, while being anchored onto SiOz/A1203 as linear 2-coordinate Cu+. Photoluminescence measurements of the catalysts and...

The influence of hydrazine reduction on metal dispersion, particle size distribution, and support morphology was investigated for a series of bimetallic Ru-AuiMgO catalysts. The catalysts were prepared by impregnation of MgO with chlorine-containing precursor salt solutions. Hydrazine reduction significantly lowered the residual chlorine content of the catalysts and allowed the formation of hig...

The complete oxidation of n-Hexane and iso-Octane was studied individually in a fixed bed tubular flow reactor over CuO-CeO2 catalysts synthesized via four different methods namely urea-nitrate combustion method, urea gelation/co-precipitation method, citric acid sol-gel method and co-impregnation method. Laser diffraction was employed in catalysts characterization. The results obtained from th...

A biomimetic model complex of the [FeFe]-hydrogenase active site (FeFeOH) with an ethylene bridge and a pendant hydroxyl group has been synthesized, characterized evaluated as catalyst for light-driven hydrogen production. The interaction present in 3-isocyanopropyltriethoxysilane provided carbamate triethoxysilane bearing diiron dithiolate (NCOFeFe), thus becoming potentially promising candida...

Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation JAVIER BARRIENTOS Akademisk avhandling som med tillstånd av KTH i Stockholm framlägges till offentlig granskning för avläggande av teknologie doktorsexamen fredagen den 23 september kl. " True wisdom comes to each of us when we realize how little we understand about life, ourselves, and the world around us....

Homogeneous catalysts usually show higher catalytic activities than heterogeneous catalysts because of their high dispersion of catalytically active sites. We demonstrate here that heterogeneous catalysts of ionic liquids functionalized on superhydrophobic mesoporous polymers exhibit much higher activities in transesterification to form biodiesel than homogeneous catalysts of the ionic liquids ...