Identification of relevant active sites and a mechanism study for reverse water gas shift reaction over Pt/CeO2 catalysts

Abstract Reverse water gas shift (RWGS) reaction can serve as a pivotal stage in the CO 2 conversion processes, which is vital for the utilization of CO 2 . In this study, RWGS reaction was performed over Pt/CeO 2 catalysts at the temperature range of 200–500 °C under ambient pressure. Compared with pure CeO 2 , Pt/CeO 2 catalysts exhibited superior RWGS activity at lower reaction temperature. Meanwhile, the calculated TOF and E a values are approximately the same over these Pt/CeO 2 catalysts pretreated under various calcination conditions, indicating that the RWGS reaction is not affected by the morphologies of anchored Pt nanoparticles or the primary crystallinity of CeO 2 . TPR and XPS results indicated that the incorporation of Pt promoted the reducibility of CeO 2 support and remarkably increased the content of Ce 3+ sites on the catalyst surface. Furthermore, the CO TPSR-MS signal under the condition of pure CO 2 flow over Pt/CeO 2 catalyst is far lower than that under the condition of adsorbed CO 2 with H 2 -assisted flow, revealing that CO 2 molecules adsorbed on Ce 3+ active sites have difficult in generating CO directly. Meanwhile, the adsorbed CO 2 with the assistance of H 2 can form formate species easily over Ce 3+ active sites and then decompose into Ce 3 + –CO species for CO production, which was identified by in-situ FTIR.