Promotional nature of Sn on Pt/CeO2 for the oxidative dehydrogenation of propane with carbon dioxide

The oxidative dehydrogenation of propane with CO2 (CO2-ODP) is a promising technology for the efficient production of propene in tandem with CO2 reduction to CO. However, the rational design of high-performance catalysts for this green process is still challenged by limited understanding of the nature of active sites and the reaction mechanism. In this work, the effects of SnO2 promoter on Pt/CeO2 activity and propene selectivity in CO2-ODP are elucidated through varying the Sn/Pt molar ratio. When the ratio increases, propane conversion gradually decreases, while the propene selectivity increases. These dependences are explained by increasing the electron density of Pt through the promoter. The strength of this effect is determined by the Sn/Pt ratio. Owing to the electronic changes of Pt, CO2-ODP becomes more favorable than the undesired CO2 reforming of propane. Sn-modified Pt-O-Ce bonds are reasonably revealed as the active sites for CO2-ODP occurring through a redox mechanism involving the activation of CO2 over oxygen vacancies at Sn-modified Pt and CeO2 boundaries. These atomic-scale understandings are important guidelines for purposeful development of high-performance Pt-based catalysts for CO2-ODP.