ROOM-TEMPERATURE OXIDATION OF K2CO3/MOS2 CATALYSTS AND ITS EFFECTS ON ALCOHOL SYNTHESIS FROM CO AND H2

Abstract

Potassium-promoted MoS2 is used as a catalyst for mixed alcohol synthesis from CO and H2. This study investigates the room-temperature oxidation of the catalyst and its effect on the surface structure and catalytic activity in alcohol synthesis at 573 K and 1.5 MPa. Catalysts were stored in the atmosphere or in a vacuum oven for several weeks. The characterization of catalyst was performed using XRD, XPS, FT-IR, and TGA/DTA methods. The XPS data of K2CO3/MoS2 stored in the atmosphere for extended periods indicated the oxidations of Mo(IV) (as sulfide) to Mo(VI) (as oxide) as well as S2- (as sulfide) to S6+ (as sulfate) on the MoS2 surface. The IR results showed that sulfate species first produced by oxidation had Td symmetry, which was further transformed into C2ν (bidentate) upon a prolonged storage. The sulfate species formed on the catalyst surface were stable until they were decomposed above 1000 K. The oxidized K2CO3/MoS2 catalyst showed enhanced catalytic activity and high selectivity to C2+ hydrocarbons, rather than forming alcohols as did fresh K2CO3/MoS2. These modified catalytic properties were similar to those of fresh K2SO4/MoS2. © 1992.