A shape-selective platinum-loaded mordenite catalyst for the hydrocracking of paraffins by the chemical vapour deposition of silicon alkoxide

Abstract

A platinum-loaded H-mordenite (PtHM) catalyst has been modified by the chemical vapour deposition of silicon alkoxide in order to improve its shape-selectivity for the hydrocracking of paraffins. The paraffins reacted on the silica-coated PtHM according to their molecular size, and reactant shape-selectivity was achieved by choosing the extent of modification. Silica was only deposited on the external surface of the zeolite to form mono-, di- or tri-layers of SiO₂, with the internal acid and metal sites unpoisoned, thus effectively narrowing the pore exit size only. Platinum metal on the external surface was not completely covered by the silicon oxide.