A series of supported Mo-based catalysts for methanethiol synthesis from high H₂S-containing syngas were investigated by kinetics and XPS, ESR characterization.The activity evaluating results show that upon the potassium-promoted Mo-based catalysts, the methanethiol will become dominant product of the reaction, and the activity sequence of several Mo-based catalysts for the reaction is as follows: K₂MoO₄/CoO/SiO₂K₂MoO₄/SiO₂MoO₃/K₂CO₃/SiO₂K₂MoS₄/SiO₂MoS₂/K₃CO₃/SiO₂.In the ESR characterization of the catalysts used the resonant signals of "oxo-Mo(V)" and "thio-Mo(V)" can be detected.The XPS characterization indicates that mixed valence Mo species Mo⁴⁺, Mo⁵⁺ and Mo⁶⁺ and three kinds of S species S^2-, (S—S)^2- and S⁶⁺ exist in the catalysts.As a promoter CoO was introduced into Mo-based catalysts.It was observed that the addition of CoO leads to decrease of the amount of "oxo-Mo(V)" in the catalysts, but increase of the amount of "thio-Mo(V)", which may be connected with "Mo-S-K" phase or "Co-Mo-S-K" phase, meanwhile CoO in the catalyst was found to enhance the formation of S^2-, but inhibit the formation of (S—S)^2-.It was found also that the methanethiol synthesis is favored if the peak intensity ratios of (Mo⁴⁺+Mo⁵⁺)/Mo⁶⁺ and S^2-/(S—S)^2- are kept at about 0.75 and 1 level respectively.A possible mechanism about the relationship of CH₃SH formation with "Mo-S-K" phase was proposed.

Key words: methanethiol, H₂S-containing syngas, Mo-based catalyst