Ethane oxidative dehydrogenation by CO2 over stable CsRu/CeO2 catalyst

• ODH of ethane by CO 2 is an energy-efficient way of utilizing shale gas. • The reversion between Ce 3+ and Ce 4+ keeping the catalyst active and stable. • CsRu/CeO 2 has higher selectivity of light olefins than Ru/CeO 2 . Oxidative and non-oxidative ethane dehydrogenation were studied and compared over Cs-promoted Ru/CeO 2 catalyst. The presence of CO 2 improved the ethane conversion to ethylene and led to the formation of C 3 and C 4 olefins as well. The olefin selectivity and yield in ODH were affected by reaction variables including CO 2 /C 2 H 6 ratio, temperature, and feed rate. The CsRu/CeO 2 remained stable activity for 93 days under reactive conditions wherein intermittent shutdowns and startups were performed. Mechanistically, the interaction between Cs and Ru with ceria in the crystalline structure facilitated reduction and oxidation cycles. It was postulated that Ce 3+ had a strong tendency to react with CO 2 to form Ce 4+ , whereas Ce 4+ was reduced by hydrogen from ethane dehydrogenation to form Ce 3+ . The redox cycle can be repeated during the ODH reaction keeping the catalyst active. Furthermore, in the ODH reaction, the CsRu/CeO 2 catalyst exhibited resistance to carbon deposition, evidenced by the carbon balance measurement.