Hydrogen production over Co-promoted Mo-S water gas shift catalysts supported on ZrO2

[Display omitted] •Co addition enhanced the WGS activity of Mo-S/ZrO2 catalysts.•The formation of CoMo-S species increased with Co content up to Co/Mo = 0.3.•CO conversion was stable during 4 weeks of WGS reaction in 7000 ppm H2S containing feed at 35,000 h−1 GHSV and 350 °C.•The optimal atomic Co/Mo ratio at monolayer coverage on ZrO2 resulted in enhanced WGS activity.•The active metal loading in the best CoMo-S catalyst was lower than in pure Mo-S/ZrO2 and commercial catalysts. A series of CoMo-S/ZrO2 catalysts were prepared by modifying Co and Mo content using incipient wetness impregnation method, investigated in the water gas shift (WGS) reaction in the presence of H2S and characterized by TEM, XRD, Raman, TPR, and XPS. The supported CoMo-S catalyst corresponding to the CoMo-O monolayer coverage displayed the presence of highly dispersed CoMo-S species that were characterized by the highest extent of sulfidation. The presence of cobalt facilitated the formation of active CoMo-S species that were more H2S-dependent as compared to Mo-S entities. The Co/Mo = 0.3 catalyst at monolayer CoMo-O coverage was the most active and thermally stable, as well as the least H2S-dependent during 4 weeks of WGS reaction among all catalysts investigated.