Copper-doped CeZn catalysts for efficient CO$_2$-assisted oxidative dehydrogenation of propane: Mechanistic insights and performance optimization

The use of CO$_2$ as a mild oxidant for the oxidative dehydrogenation of propane (CO$_2$-ODHP) is crucial for achieving net-zero carbon emissions and mitigating greenhouse gases that contribute to global warming. In this study, a CeZn catalyst was synthesized using the wet impregnation method and applied for CO$_2$-ODHP. Incorporating Cu into the (CeZn) lattice enhanced both propane conversion and yield by leveraging the redox properties of (CeZn) to activate CO$_2$ into CO and O*, which facilitated the cleavage of propane Csingle bondH bonds. Characterization of the catalyst’s physicochemical properties revealed that doping Cu into (Ce/Zn) significantly increased the specific surface area and pore volume due to the presence of Cu$^{2+}$ species, promoting the mobility of lattice oxygen (O$_{Lat}$), and thereby improving C$_3$H$_8$ conversion. Additionally, the transfer of oxygen from Ce$^{4+}$ to Ce$^{3+}$ during the reaction contributed to the highest propene selectivity observed for the copper-free catalyst. The catalytic activity was maintained even after several hours of propane conversion at 550 °C. All catalysts demonstrated relatively stable performance, with the highest and lowest relative deactivation rates of < 6 % and 4 %, respectively, observed in 0 %Cu(Ce/Zn) and 3 %Cu(Ce/Zn). ... mehrDFT calculations revealed that the CuO-ZnO cluster on the CeO$_2$ (111) surface effectively promotes the activation of CO$_2$. Thus, modifying (Ce/Zn) with Cu is a promising strategy for enhancing propene yield in CO$_2$-ODHP.