Christian Forquy

Synthesis of methyl mercaptan from carbon oxides and H2S with tungsten-alumina catalysts

Abstract The direct synthesis of methylmercaptan from carbon oxide(s) (CO or CO2), hydrogen sulfide and hydrogen was studied in the presence of tungsten-based catalysts. The optimization of W—K—Al2O3 catalysts makes it possible to obtain rather high activity and selectivity while keeping a fair stability. The main steps of the reaction are the formation of carbonylsulfide and hydrogenation of carbonylsulfide to methylmercaptan. The second step is generally the slow one, owing to the low hydrogenating properties of sulfide catalysts. Water has a strong inhibiting effect in the (CO2, H2S, H2) reaction and the activity of the catalyst is lower than in the (CO, H2, H2S) reaction. ESCA experiments provide some important information on the behaviour of these catalysts during the sulfidation step of the catalytic reaction(s).