A study on the sulfur-resistant catalysts for water gas shift reaction - I. TPR studies of Mo/gamma-Al2O3 catalysts

Mo/gamma-Al2O3 catalysts were prepared by impregnation method in various co nditions to identify the states of surface Mo species. TPR (Temperature-Pro grammed Reduction) and Raman spectroscopy were applied to analyze the surfa ce Mo species. TPR analysis revealed that MoO3 was reduced to Mo through Mo O2, the intermediate state and the increase of Mo loading enhanced the redu cibility of Mo oxide till the formation of monolayer coverage. High tempera ture calcination induced oxygen defects in MoO3 giving their unstable state s for easier reduction. Raman spectroscopy analysis showed that the increas e of Mo loading induced the polymeric Mo oxide.