Controllably Modulating Oxygen Vacancies on Nonstoichiometric Nd−Ce−O Binary Oxides for Low‐temperature Oxidative Coupling of Methane

Abstract Herein, we synthesised a series of nonstoichiometric Nd−Ce−O composite oxides with a fluorite or rare‐earth C‐type phase structure using the glycine combustion method for the oxidative coupling of methane (OCM) reaction. As the amount of Nd 3+ increases, the oxygen vacancies in this series of composite oxides gradually increase, leading to an amount increasing in the C 2 ‐selective oxygen species O 2 − generated by the oxygen vacancies. In addition, with the increase in Nd 3+ , the number of moderate basic sites on the catalyst surface also improves, another significant factor affecting the OCM reaction performance of the composite oxides. Nd 0.9 Ce 0.1 O 1.55 possesses optimal low‐temperature OCM reaction performance, achieving 8.0 % C 2 yield at 450 °C and 14.1 % C 2 yield at 700 °C. This can be attributed to the nonstoichiometric rare‐earth C‐type crystalline phase structure of Nd 0.9 Ce 0.1 O 1.55 , which exhibits the highest abundance of oxygen vacancies, selective oxygen species O 2 − , and moderate basic sites.