High-Throughput Experiments and Kinetic Modeling of Oxidative Coupling of Methane, OCM Over La₂O₃/CeO₂ Catalyst

A reliable dataset covering a parametric space of process conditions is essential for realizing catalyst informatics. A high-throughput screening (HTS) instrument was employed to obtain a parametric dataset to develop a detailed reaction microkinetic model for the oxidative coupling of methane (OCM) over La₂O₃/CeO₂ catalyst. The model was combined with well-validated gas-phase kinetics to describe the interactions between homogeneous and heterogeneous reaction chemistry. Methane and oxygen conversions and selectivities of ethylene, ethane, carbon monoxide, and carbon dioxide were measured experimentally in the temperature range of 500-800 °C, CH₄/O₂ ratio between 3-13, and pressure between 1 to 10 bar. The proposed reaction network consists of 52 irreversible elementary steps describing catalytic reactions between 11 surface species and 123 reversible steps describing the contribution of gas-phase between 25 species. A packed-bed reactor model was developed based on dimensions of experimental setup and catalyst characterization results to account for homogeneous-heterogeneous interactions. The proposed mechanism was tested and validated over a wide range of operating conditions and showed a reasonable fit with an average difference of less than 5% compared to experimentally measured methane conversion and selectivities of ethylene and ethane. Rate-of-production (ROP) and sensitivity analysis were performed to identify main reaction pathways and highlight the important reactions in the OCM.