Facet-Specific Bifunctional Li–La/MgO Catalyst for Oxidative Coupling of Methane with High Ethylene Yields and Thermal Stability

The oxidative coupling of methane (OCM) to produce ethylene remains a critical challenge due to inherently low yield, deep oxidation, and catalyst deactivation. This study reports a Li–La co-loaded MgO catalyst (Li–La/MgO) with bifunctional active sites, which significantly improves the ethylene yield and catalyst stability in OCM. The catalyst achieves a maximum ethylene yield of 15.1% and a high ethylene formation rate of 1.31 mol·g –1 ·h –1 achieved at 900 °C. The Li and La sites on a specific MgO(111) facet promote the activation of methane and oxygen, respectively, limiting deep oxidation by suppressing the competition adsorption. Furthermore, the surface-anchored structure formed between La 2 O 3 and Li 2 CO 3 effectively prevented lithium loss from the catalyst. After 100 h of continuous operation at 900 °C, the Li–La/MgO catalyst maintained an ethylene yield of approximately 15%, demonstrating markedly improved catalytic stability. This work provides a valuable insight for designing bifunctional catalysts with improved ethylene productivity and long-term stability in OCM.