Response in the catalytic properties to presulphidation for promoted and nonpromoted molybdenum hydrorefining catalysts

Abstract

The sensitivity of nonpromoted molybdenum catalysts to presulphidation was examined on the adsorption of hydrocarbons and pyridine, hydrodesulphurization of thiophene and benzothiophene, and cracking and dehydrogenation of isopropylbenezene. Published data of other authors concerning the hydrodesulphurization of thiophene and benzothiophene and hydrogenation of cyclohexene were also evaluated. In all cases except the dehydrogenation of isopropylbenzene, the change in the adsorption properties and catalysts activity brought about by the presulphidation were lower for the nonpromoted catalysts than for the promoted ones, thus indicating that cobalt is directly involved in the active surface of CoMo/Al2O3 catalysts.