Influence of the Au-Rh /ASA catalyst preparation method on the benzene hydrogenation reaction

Abstract

Comparative hydrogenation of benzene and toluene in ethanol under hydrogen pressure on rhodium and gold supported on synthetic amorphous aluminosilicate (ASA, trade name is siral-40)   with a developed surface area prepared by two methods: impregnation by using the incipient wetness technique and colloidal method. Moreover, the catalysts were prepared by impregnation in two versions: co-impregnation and sequential impregnation of rhodium and gold salts. The catalysts are characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES) methods. It is shown that the catalysts prepared by impregnation according to the incipient wetness technique were the most acceptable for selective hydrogenation of benzene. The activity of the catalyst depends on the amount of rhodium on the surface of the available surface for the activation of benzene and toluene. On catalysts prepared by the colloidal method, the active metal rhodium goes inside the pores, and gold on the surface, so the activity is low, while on catalysts prepared by impregnation, the amount of rhodium on the surface is close to the theoretically possible amount. The selectivity of benzene hydrogenation in the presence of toluene on this catalyst is 84%.