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

Reverse water gas shift（RWGS） reaction can serve as a pivotal stage in the COconversion processes,which is vital for the utilization of CO.In this study,RWGS reaction was performed over Pt/CeOcatalysts at the temperature range of 200-500℃ under ambient pressure.Compared with pure CeO,Pt/CeOcatalysts exhibited superior RWGS activity at lower reaction temperature.Meanwhile,the calculated TOF and Evalues are approximately the same over these Pt/CeOcatalysts 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.TPR and XPS results indicated that the incorporation of Pt promoted the reducibility of CeOsupport and remarkably increased the content of Cesites on the catalyst surface.Furthermore,the CO TPSR-MS signal under the condition of pure COflow over Pt/CeOcatalyst is far lower than that under the condition of adsorbed COwith H-assisted flow,revealing that COmolecules adsorbed on Ceactive sites have difficult in generating CO directly.Meanwhile,the adsorbed COwith the assistance of Hcan form formate species easily over Ceactive sites and then decompose into Ce-CO species for CO production,which was identified by in-situ FTIR.