Adaptacao da Porosidade de Zeolitos ZSM-5 para Reaccoes Selectivas (PorosityAdaptation of ZSM-5 Catalysts for Selective Reactions)

摘要

Porosity adaptation of ZSM-5 catalysts by chemical vapor deposition of variousspecies was performed in order to make them more selective. The solids were synthesized with different morphologies and Si/Al ratios. Modifications of the porosity were obtained on a gas-solid reaction between zeolites and the following species: SiCl4, Si(OCH3)4, ZnCl2 and GaCl3. Slight modifications on the acidity and on the porous volume of the catalysts were observed. The catalytic behavior of all ZSM-5 modified zeolites was investigated through the alkylation of toluene by methanol at 350C. The modified solids shown an enhanced selectivity for p-xylene and p-ethyltoluene. The study of the transformation of propane and propene on the metallic grafted catalysts (ZnHZSM-5 and GaHZSM-5) was performed at 530 C. It was found that zinc and gallium species have dehydrogenating activity, increasing both propane activation and naphthene aromatization.