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.