Activity of cobalt sulfide catalysts in the hydrogenolysis of dimethyl disulfide to methanethiol: Effects of the nature of a support and the procedure of supporting a cobalt precursor

Abstract

The conversion of dimethyl disulfide to methanethiol on various catalysts containing supported cobalt sulfide in an atmosphere of hydrogen was studied at atmospheric pressure and T = 190°C. On CoS introduced into the channels of zeolite HSZM-5, the process occurred at a high rate but with a low selectivity for methanethiol because the proton centers of the support participated in a side reaction with the formation of dimethyl sulfide and hydrogen sulfide. Under the action of sulfide catalysts supported onto a carbon support, aluminum oxide, silicon dioxide, and an amorphous aluminosilicate, the decomposition of dimethyl disulfide to methanethiol occurred with 95–100% selectivity. The CoS/Al2O3 catalysts were found to be most efficient. The specific activity of alumina-cobalt sulfide catalysts only slightly depended on the phase composition and specific surface area of Al2O3. The conditions of the thermal treatment and sulfurization of catalysts and, particularly, the procedure of supporting a cobalt precursor onto the support were of key importance. Catalysts prepared through the stage of supporting nanodispersed cobalt hydroxide were much more active than the catalysts based on supported cobalt salts.