Partial oxidation of methane to syngas in catalytic membrane reactor: role of catalyst oxygen vacancies

Abstract

Methane partial oxidation (POM) by a catalytic membrane reactor is a promising process by integration of oxygen separation and catalytic reaction to produce syngas, an important feedstock for downstream processes. However, high methane conversion and syngas yield require high temperature operation (>850 °C) due to dry/steam reforming involvement, which leads to high-energy consumption and poor catalyst stability. In this study, a novel asymmetric membrane reactor incorporated with a catalyst layer of enriched oxygen vacancy was designed for direct partial oxidation (DPO) of methane to syngas. A composite of Sm₀.₂Ce₀.₈O₂₋δ (SDC)/γ–Al₂O₃ supported Ni catalyst was coated on La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃₋δ (LSCF) membrane for the reactor. It was found that activated oxygen species (O₂⁻² and O⁻²) from SDC surface favours syngas formation (86% CH₄ conversion and 92.5% CO selectivity) on the catalyst layer at 750 °C. The introduction of oxygen vacancies to the catalyst layer maintains the active oxygen species in catalysis and promotes DPO of methane over CH₄ combustion at reduced temperature.