Promoting effect of carbon dioxide on the dehydrogenation of ethylbenzene over silica-supported vanadium catalysts

► CO2 has a prominent promoting effect on ethylbenzene (EB) dehydrogenation. ► EB dehydrogenation over VOx/SiO2 in CO2 may follow a redox mechanism. ► CO2 can effectively keep/regain high valence active vanadium species. ► CO2 can alleviate catalyst deactivation, but cannot suppress coke formation. ► Coke quantity deposited is only related to the amount of EB converted.