A Homogeneous-Heterogeneous Kinetic Study of Oxidative Coupling of Methane (OCM) on La₂O₃/CeO₂ Catalyst

A La₂O₃/CeO₂ catalyst was synthesized and achieved 19 % C₂₊ yield with 65 % C₂₊ selectivity at 650 °C. The doping of CeO₂ not only enhanced catalytic performance, but also improved catalyst stability in the presence CO₂ and H₂O. This study investigated the kinetics on La₂O₃/CeO₂ over a wide range of operating conditions. Planar laser-induced fluorescence was implemented to directly observe the presence of formaldehyde, as the first time reported in OCM. A packed bed reactor model was constructed based on the dimensions of experimental setup and catalyst characterization. Rather than using a tuned gas phase model, the experimentally validated mechanism NUIGMech1.1 was implemented. The proposed homogeneous-heterogeneous OCM mechanism kinetic model was validated against experimental data under isothermal conditions, and the results show good agreement with measured species. The rate of production (ROP) was performed to identify the important reactions and prove the necessity of surface reactions for the OCM process.