Influence of Carbonization Conditions on Structural and Surface Properties of K-Doped Mo 2 C Catalysts for the Synthesis of Methyl Mercaptan from CO/H 2 /H 2 S.

The cooperative transition of sulfur-containing pollutants of H₂S/CO/H₂ to the high-value chemical methyl mercaptan (CH₃SH) is catalyzed by Mo-based catalysts and has good application prospects. Herein, a series of Al₂O₃-supported molybdenum carbide catalysts with K doping (denoted herein as K-Mo₂C/Al₂O₃) are fabricated by the impregnation method, with the carbonization process occurring under different atmospheres and different temperatures between 400 and 600 °C. The CH₄-K-Mo₂C/Al₂O₃ catalyst carbonized by CH₄/H₂ at 500 °C displays unprecedented performance in the synthesis of CH₃SH from CO/H₂S/H₂, with 66.1% selectivity and a 0.2990 g·g_cat⁻¹·h⁻¹ formation rate of CH₃SH at 325 °C. H₂ temperature-programmed reduction, temperature-programmed desorption, X-ray diffraction and Raman and BET analyses reveal that the CH₄-K-Mo₂C/Al₂O₃ catalyst contains more Mo coordinatively unsaturated surface sites that are responsible for promoting the adsorption of reactants and the desorption of intermediate products, thereby improving the selectivity towards and production of CH₃SH. This study systematically investigates the effects of catalyst carbonization and passivation conditions on catalyst activity, conclusively demonstrating that Mo₂C-based catalyst systems can be highly selective for producing CH₃SH from CO/H₂S/H₂. [ABSTRACT FROM AUTHOR]