Theoretical Study on the Structure Sensitivity of La₂O₂CO₃ in Oxidative Coupling of Methane and Its Comparison with La₂O₃

Converting methane into C2+ hydrocarbon products through oxidative coupling of methane (OCM) can more effectively enhance the utilization value of methane, and previous studies are usually focused on La2O3, but there are few reports on the derivative catalyst La2O2CO3. Therefore, this work aims to deeply explore the structural sensitivity of La2O2CO3 in the OCM reaction and compare its catalytic performance with that of La2O3. In this article, we used DFT calculations and microkinetic simulations to investigate the reaction mechanisms on the surfaces of La2O3(110), La2O2CO3(100), and La2O2CO3(110), and explored the catalytic activity and C2+ species selectivity of different crystal planes for the OCM reaction. The calculation results show that the La2O2CO3 catalyst with higher selectivity for C2+ species compared to the La2O3 catalyst, based on the difference in activation energy between the CH3· decomposition reaction and the CH3· coupling reaction. Microkinetic simulations reveal that methane oxidative decomposition is the main rate-limiting step in the entire OCM reaction process, and the La2O2CO3 (110) surface is more favorable for the formation of C2+ species than that of La2O2CO3 (100). It is hoped that the findings of this study can deepen researchers’ understanding of the OCM reaction mechanism and provide important theoretical guidance and practical reference for the development of more efficient and selective catalysts.