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Alunihum and gallium isomorphs of omega zeolites in Na(super +), H(super +) and La(super 3+) cationic forms re characterized by equilibrium sorption uptakes of different probe molecules such as water, benzene and n-hexane. For NH3 sorption, Na-Al-omega offered the most homogeneous surface, whereas the other cation forms showed herteogeneous characters of the surface.

Epoxidation of styrene over vanadium silicalite with ferrierite (FER) type topology is undertaken. Influence of temperature, pressure, various solvents and solvent to substrate mole ratio was investigated. Conversion increased with increase in temperature and pressure. Solvent to substrate mole ratio is found to play a crucial role in increasing the conversion and selectivity. Catalytic activity of V FER was compared with those of Ti FER, TS 1 and Fe FER. In the case of V and Ti ferrierite analogs, styrene oxide was the major product, whereas phenylacetaldehyde was the major product in the case of TS 1. The catalyst could be recycled after washing by a suitable solvent such as acetone and showed no significant loss in catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: The liquid-phase acylation of veratrole with acetic anhydride and alkylation of toluene with 1-dodecene were carried out over WO x /ZrO2 solid acid catalysts. The catalysts were prepared by wet impregnation method using zirconium oxyhydroxide and ammonium metatungstate. Catalysts with different WO3 loading (5–30wt.%) were prepared and calcined at 800°C and catalyst with 15% WO3 was calcined from 650 to 850°C. All the catalysts were characterized by nitrogen adsorption, XRD and NH3-TPD. The catalyst with 15% WO3 calcined at 800°C (15 WZ-800) was found to be the most active in acylation and alkylation reactions. The effect of temperature, molar ratio and catalyst weight on the conversions of acetic anhydride and dodecene were studied in detail. The catalyst 15 WZ-800 gave 67% acetic anhydride conversion in veratrole acylation under the reaction conditions of 70°C, veratrole/acetic anhydride molar ratio 2, time 4h and 99% dodecene conversion with >99% monododecyl toluene selectivity at 100°C, toluene/1-dodecene molar ratio 10 and time 1h. [Copyright &y& Elsevier]

Cu-ZSM-5 and Cu-AlTS-1 catalysts were prepared by solid state ion exchange and studied in DeNOx reactions. A NO3 type surface complex was found to be an active intermediate in the decomposition of NO and N2O. Copper was oxidized to Cu2+ in the decomposition reactions. Oscillations at full N2O conversion were observed in the gas phase O2 concentration, without any change in the N2 concentration. The oscillation was synchronized by gas phase NO formed from the NO3 complex. The same complex seems to be an active intermediate also in NO selective catalytic reduction (SCR) by methane, whereas carbonaceous deposits play a role in NO SCR by propane. TPD reveals that only 10–20% of the total copper in the zeolites participates in the catalytic cycles. [Copyright &y& Elsevier]