Study of heterogeneous catalytic processes over cobalt, molybdenum, and cobalt-molybdenum catalysts supported on alumina studied by temperature-programmed desorption and temperature-programmed reaction .4. Conversions of propanethiol and butanethiol

Propanethiol and butanethiol conversions on Co black and alumina-supported Co, Mo, and Co-Mo catalysts are studied by the method of temperature-programmed reaction. It is found that all the catalysts have several types of active sites on which the rupture of the C-S bond in thiol molecules occurs. More complete conversion of the sulfur-containing substances to corresponding hydrocarbons (propanethiol to propene and propane and butanethiol to butene and butane) proceeds on the sites characterized by stronger bonding with thiol molecules. A two-route mechanism for desulfurization of propanethiol and butanethiol is proposed. The first route involves elimination of the beta-hydrogen atom and simultaneous dissociation of the C-S bond in thiol molecules to yield unsaturated hydrocarbons, whereas hydrogenation of the alpha-carbon atom and simultaneous rupture of the C-S bond to give rise to saturated hydrocarbons occur via the second route.