Catalytic partial oxidation of methane to syngas: review of perovskite catalysts and membrane reactors

Partial oxidation of methane (POM) offers a promising option to produce syngas for downstream processes such as hydrogen production and Fischer-Tropsch processes. POM in fixed-bed reactors requires an oxygen separation plant with high operation cost and safety risks. On the contrary, membrane reactors can provide an improved process by integrating both oxygen separation and catalytic reaction processes. With many advantages including high purity and efficient oxygen separation from the air at the catalytic reaction conditions, mixed ionic-electronic conducting membranes (MIEC) caught great attention in the scientific research field over the past two decades. In this review, POM using different catalysts in fixed-bed reactors was firstly summarized with emphasizing on perovskite-based catalysts, and then the material screening of MIEC membrane reactors was introduced and linked to the selection of conventional and perovskite catalysts. The catalytic activity, reaction mechanisms, and emerging challenges have been analyzed. Furthermore, future research directions have been outlined by highlighting the effect of electronic properties, continuous reduction-oxidation in the presence of oxygen flux, and chemical reaction mechanism on membrane/catalyst

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

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 SmCeO (SDC)/γ–AlO supported Ni catalyst was coated on LaSrCoFeO (LSCF) membrane for the reactor. It was found that activated oxygen species (O and O) from SDC surface favours syngas formation (86% CH 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 CH combustion at reduced temperature