Oxygen-Vacancies Enriched SrMnO3 for Chemical Looping Oxidative Dehydrogenation of Ethylbenzene

Abstract

Oxygen vacancies (OV) affect the catalytic activity of the catalyst by changing the crystal and electronic structure. Therefore, the regulation of the oxygen vacancy is the key to enhancing the catalytic ability of the catalysts. This paper presents a way to regulate OV in SrMnO₃ during chemical looping oxidative dehydrogenation (CL-ODH) for ethylbenzene by incorporating urea into the conventional citrate process. The creation of oxygen vacancies can be regulated by modifying the quantity of urea introduced, thereby enhancing the oxygen storage capabilities and catalytic efficacy of the catalyst. The optimized catalyst demonstrated effective dehydrogenation activity at 500 °C, but the material became deactivated after the initial 13 redox cycles. This results from the extensive carbonization and degradation of the perovskite catalyst’s structure. The deactivated catalyst was decarbonized in an oxygen environment at 950 °C, while the carbonate was successfully removed, and the perovskite structure was restored. Moreover, the decarbonized catalyst maintained 90% ethylbenzene conversion and 95% styrene selectivity in the redox cycle at 500 °C. This study provides a strategy for modulating oxygen vacancies on oxygen carriers and also offers novel perspectives for designing efficient ODH catalysts, which has significant potential for energy savings in styrene production.