PT-AU/AL2O3 CATALYSTS - PREPARATION, CHARACTERIZATION, AND DEHYDROGENATION ACTIVITY

The physicochemical characteristics of Pt-Au catalysts, such as the dispersion, chemisorption. and thermodesorption of hydrogen, have been studied in terms of gold content. The catalysts were prepared by coimpregnation of a γ-alumina by a mixture of hexachloroplatinic and tetrachloroauric acids, calcination in oxygen and slow reduction in H2-He from 25 to 400°C. The most outstanding result is the very large increase in the dispersion with the gold concentration. For example, with the alloy containing 80% gold more than 70% of the detectable particles are below 10 Å. In the same way, the activity per site and the selectivity in the dehydrogenation of methylcyclohexane to toluene increase with the gold concentration. © 1993 Academic Press, Inc.