Molecular-level investigation on supported CrOx catalyst for oxidative dehydrogenation of propane with carbon dioxide

•Highly dispersed CrSiβ catalyst is prepared via a two-step post-synthesis method.•The 3CrSiβ catalyst shows the best performance for CO2-ODP.•The amount of Cr6+ oxides is responsible for the activity of CrSiβ for CO2-ODP.•In-situ formed coordinatively unsaturated Cr3+ oxides are active sites for CO2-ODP.•A detailed redox mechanism including the formation of active sites is proposed.