Research progress of CO_(2)oxidative dehydrogenation of propane to propylene over Cr-free metal catalysts

CO_(2)-assisted oxidative dehydrogenation of propane(CO_(2)-ODHP)is an attractive strategy to offset the demand gap of propylene due to its potentiality of reducing CO_(2)emissions,especially under the demands of peaking CO_(2)emissions and carbon neutrality.The introduction of CO_(2)as a soft oxidant into the reaction not only averts the over-oxidation of products,but also maintains the high oxidation state of the redox-active sites.Furthermore,the presence of CO_(2)increases the conversion of propane by coupling the dehydrogenation of propane(DHP)with the reverse water gas reaction(RWGS)and inhibits the coking formation to prolong the lifetime of catalysts via the reverse Boudouard reaction.An effective catalyst should selectively activate the C–H bond but suppress the C–C cleavage.However,to prepare such a catalyst remains challenging.Chromium-based catalysts are always applied in industrial application of DHP;however,their toxic properties are harmful to the environment.In this aspect,exploring environment-friendly and sustainable catalytic systems with Cr-free is an important issue.In this review,we outline the development of the CO_(2)-ODHP especially in the last ten years,including the structural information,catalytic performances,and mechanisms of chromium-free metal-based catalyst systems,and the role of CO_(2)in the reaction.We also present perspectives for future progress in the CO_(2)-ODHP.