Catalytic and Electronic Properties of Platinum Particles Encaged in Zeolite. Particles Size and Environment Effects on N-Butane Conversion

The catalytic activity in n-butane conversion of platinum particles encaged in Y-type zeolites has been studied as a function of particle size, support acidity, exchange of Ce 3+ ions and presence of Mo atoms. A correlation has been found between the hydrogenolysis rates and the electrophilic character (e.c.) of the metal evaluated from X-ray absorption edge spectroscopy. It is assumed that the e.c. of Pt in PtCeY and PtNaHY zeolites modifies the adsorption equilibrium between H 2 and n-C 4 H 10 on the surface. The platinum is not electrophilic in PtMoY zeolite. The high activity of this catalyst seems to be due to a synergetic effect of Pt and Mo both participating in the reaction mechanism.