Catalytic para-xylene maximization II -: alkylation of toluene with methanol on platinum loaded H-ZSM-5 zeolite catalysts prepared via different routes

Two series of catalysts, A and B, each containing 0.2%, 0.4%, and 0.6% Pt on H-ZSM-5 zeolite, were prepared via two different procedures; catalysts of series A were prepared via impregnating H-ZSM-5 with the Pt precursor (H2PtCl6) solution, whereas those of series B were prepared via impregnating NH4-ZSM-5 zeolite with the Pt precursor solution followed by deammoniation to the Pt/H-ZSM-5 forms. The prepared catalysts were examined for toluene alkylation with methanol in a flow reactor under atmospheric conditions using HZ gas carrier. The catalysts were characterized for acidity magnitude and strength via temperature programmed desorption of ammonia (TPD) and for Pt dispersion in the zeolite via H-2 chemisorption. Correlation of the catalysts characteristics with their reactivities for toluene conversion, xylenes production, trimethylbenzenes formation and xylene isomers in product relative to their thermodynamic equilibrium values were carried out. (C) 1999 Elsevier Science B.V. All rights reserved.