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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·gcat−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]

• Collaborative removal and recycling treatment of CO and H 2 S into CH 3 SH is promising. • MSI, SMSI and EMSI are constructed and investigated for the synthesis of CH 3 SH. • SMSI favors the production of smaller sizes of K-MoS 2 particles and enhances the CH 3 SH formation rate. • EMSI is not in favor to the synthesis of CH 3 SH from CO/H 2 /H 2 S mixtures. Modulation of the metal-support interactions (MSI) is an effective means to improve the performance of supported catalysts, but the role of the metal-support effect in the synthesis of CH 3 SH from CO/H 2 /H 2 S mixtures has not been recognized. Here, three different interactions, namely weak MSI, strong MSI and electronic MSI are constructed over K-promoted MoS 2 -base catalysts and investigated for the synthesis of CH 3 SH. The catalytic activity experiments show that the K-Mo catalyst with strong MSI has the highest formation rate toward CH 3 SH, while the K-Mo catalyst with electronic MSI instead shows the worst formation rate toward CH 3 SH. The characterizations suggest that the strong MSI facilitates the enhancement of Mo-S bond strength and the production of few layers, shorter slab and ordered K-MoS 2 particles. The former benefits the formation and stabilization of C-S intermediate species and subsequent hydrogenation to CH 3 SH, while the latter promotes the generation of more Mo-coordinatively unsaturated sites (Mo-CUS) and thus facilitates the first-step adsorption and activation of reactants. In contrast, electronic MSI weakens the strength of the Mo-S bond, which inhibits the generation of C-S intermediate species. On the other hand, the presence of electronic MSI leads to the generation of Mo-O v -Ti interfacial sites, which is favorable for the hydrogenolysis of CH 3 SH to CH 4. This work provides an insight into the construction and selection of metal-support interactions for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]