Support Effects on Water Gas Shift Activity and Sulfur Dependence of Mo Sulfide Catalysts

Molybdenum (Mo) sulfide catalysts supported on ZrO2, Al2O3, TiO2, CeO2, and SiO2 were prepared by the incipient wetness impregnation method and explored with respect to their catalytic activity and H2S dependence in the water gas shift (WGS) reaction. The highest WGS activity at 450 °C and S/Mo atomic ratio among all Mo sulfide catalysts investigated were observed for the Mo–S/ZrO2 catalyst. Moreover, the WGS activity of the Mo–S/ZrO2 catalyst was stable for 72 h of reaction, regardless of the presence of H2S in the feed. The extent of sulfidation of supported Mo–S catalysts increased with decreasing MoO3 reduction temperature in temperature-programmed reduction, which indicated a decreased strength of MoO3–support interactions. A comparison of fresh and used supported Mo catalysts suggested that the active Mo–S sites of the Mo–S/ZrO2 catalyst maintained their catalytic activity without the crystallization of Mo–S species during 72 h of WGS reaction. Therefore, ZrO2 was indicated by this study as a promising support for the Mo-based WGS catalysts.