CATALYTIC SYNTHESIS OF METHANETHIOL FROM METHANOL AND HYDROGEN-SULFIDE

The mechanisms of the reaction between methanol and H2S at 320-500-deg rees-C in the presence of aluminum oxide that is modified with alkali metal compounds have been studied. L sites and basic sites occur on th e surface of the catalysts. The acidity of Al2O3 is reduced with the a ddition of sodium or potassium hydroxide and carbonate while the basic ity is increased compared to an alumopotassium-tungsten catalyst. In t erms of their overall activity the hydroxide and carbonate samples are superior to the tungstate sample while in terms of selectivity toward s the formation of methanethiol they are inferior to the latter. From a study of the acid-base properties of the catalysts and analysis of t he kinetic data, a reaction scheme is proposed that involves the forma tion of methanethiol via a rapid methoxylation of the surface of the c atalyst followed by reaction between the CH3O groups and activated H2S .