CO2 utilization as an oxidant in the dehydrogenation of ethylbenzene to styrene over MnO2-ZrO2 catalysts

MnO2-ZrO2 binary oxide catalytic system was applied for the effective utilization of CO2 as an oxidant in the ethylbenzene dehydrogenation (EBD) to styrene monomer (SM). MnO2-ZrO2 oxides were prepared by co-precipitation method and characterized as solid solution mixture having surface area more than 1002 g−1. 10% MnO2-ZrO2 mixed oxide catalyst exhibited conversion of 73% with the selectivity of 98% at 650 °C. The MnO2-ZrO2 binary oxides were X-ray amorphous whereas the individual oxides (MnO2 and ZrO2) having much lower surface areas were crystalline in nature. As a result, MnO2-ZrO2 binary oxides exhibited greatly elevated catalytic activity for the conversion of ethylbenzene (EB) than those of individual oxides in the presence of CO2. However, in the absence of CO2 poor catalytic activity and stabilities were observed. Gradual enhancement of activities were demonstrated in the higher CO2 to EB ratios. Hence, CO2 had a profound role as a soft oxidant by improving both activity and stability in the EBD over MnO2-ZrO2 mixed oxide catalysts.