Metal-support interactions in zeolite supported platinum catalysts.

摘要

Metal-support interactions were investigated for a set of Pt/L-zeolite and Pt/Y-zeolite catalysts. Careful preparation of the catalysts enabled us to distinguish between electronic effects and particle morphology effects. The catalysts have been characterized by chemisorption measurements, Temperature Programmed Desorption (TPD) of hydrogen, X-ray Absorption Spectroscopy (XAS) and infrared absorption spectroscopy. The infrared absorption of adsorbed carbon monoxide (CO) demonstrates that the zeolite lattice influences the specific morphology of the metal particles formed. The catalytic activity and selectivity for model probe reactions (neopentane isomerization/hydrogenolysis and n-hexane reforming) have been explained in terms of metal-support interaction effects. It was observed that both the activation energies for neopentane conversion and the aromatization selectivity for n-hexane reforming over these catalysts increased with increasing electron density of the supported metal particles. The nature of the metal-zeolite interaction is discussed.