CoOx Modified VOx/Al2O3 Catalysts for Propane Dehydrogenation in CO2 and CO2-Free Conditions

Vanadium oxide (VOx)-based catalysts for propane (C3H8) dehydrogenation (PDH) demonstrate excellent redox properties due to the multivalent property of vanadium; however, the unsatisfactory catalytic efficiency and recondite catalytic mechanisms seriously restrict their widespread applications. Herein, we proposed the doping of cobalt oxide (CoOx) species into VOx supported on alumina for simultaneously facilitating the catalytic performance in PDH with (oxidative) and without CO2 (nonoxidative). The CoOx-doped VOx species are uniformly impregnated onto alumina supports through a ligand-free wet chemical impregnation method, without any additives. The results show that the CoOx doping modulates the electronic interactions between VOx species, thus increasing the reductive capability of the catalyst and mitigating the competitive absorption of CO2 with C3H8. Consequently, superior catalytic performances are achieved in both nonoxidative and CO2-oxidative PDH reactions compared to pristine VOx species without CoOx doping. Otherwise, the dry reforming of C3H8 is significantly inhibited compared to pristine CoOx species without VOx doping. Notably, a higher and impressive conversion rate up to 55.5% for target products (C3H6) is achieved in nonoxidative PDH compared to CO2-oxidative PDH on the CoOx-doped VOx catalyst, indicative of the competitive adsorption between reactants (CO2 and C3H8) during the catalytic process. This study provides a forward-looking mechanism to establish separate reaction pathways for each reactant (CO2 and C3H8) to improve mass transfer, thereby enhancing the efficiency of CO2-oxidative PDH.