Influence of coke deposition on acidity, intercrystalline mass transfer and catalytic properties of Pt-H-ZSM-5.Al₂O₃ catalyst

Abstract

Influence of coke deposition on Pt . H-ZSM-5 Al₂O₃ catalyst on its acidity distribution, intercrystalline mass transfer, and catalytic activity/selectivity (in iso-octane cracking, o-xylene isomerization and methanol-to-aromatics conversion) has been investigated by carrying out measurements on the catalyst with different extents of coke deposition. The effective intercrystalline diffusivity of iso-octane (which does not penetrate the zeolite channels) in the catalyst at 473 K was measured by the GC pulse technique. The coke deposition has resulted in an increase in the adsorption. apparent heat of adsorption of iso-octane, and xylene isomerization activity, but a decrease in the intercrystalline diffusivity of iso-octane and para selectivity in the o-xylene isomerization and methanol conversion reactions. The influence of coke deposition (to different extents) on the catalyst on its surface, intercrystalline mass transfer, and catalytic activity/selectivity in the above reactions has been discussed.