Study of the structure and selectivity of Pt–Au catalysts supported on Al 2O 3, TiO 2, and SiO 2

Abstract

A series of Pt–Au catalysts were prepared by the impregnation method on three different supports and different atomic concentrations and were characterized by conventional electron microscopy (TEM), X-ray diffraction, and as catalytic probes in the contact reaction of n-hexane. We observed changes in morphology and particle size when Au was added to Pt. A better dispersion of the metal was measured when Al 2O 3 and TiO 2 were used as supports than with SiO 2. We performed a selectivity study of the n-hexane reaction between 523 and 623 K, where the supporting materials Al 2O 3 and TiO 2 show no catalytic activity. For the Al 2O 3 support we found that selectivity is oriented to hydrogenolysis products followed by isomerization and cyclic products. For the SiO 2 support, we observed an increase in isomerization products and a slight increase in cyclic products. For the TiO 2 support the selectivity favored hydrogenolysis products, a tendency that increased with increasing Au concentration up to a maximum at 50–50 Pt–Au.