Oxygen Transport Membrane for Thermochemical Conversion of Water and Carbon Dioxide into Synthesis Gas

Abstract

Conversion of CO2 and H2O into synthesis gas via the solar thermochemical process is usually carried out at a high temperature of above 1500 °C and requires long-term durability of metal oxide catalysts during frequent heating–cooling cycles. Herein, a dual-phase Ce0.9Pr0.1O2−δ-Pr0.6Sr0.4FeO3-δ oxygen transport membrane made of mixed metal oxides was employed for the one-step thermochemical conversion of CO2 and H2O to synthesis gas with a H2/CO ratio of 2:1. Benefitting from the in situ removal of the generated oxygen through the highly oxygen-ion permeable membrane, the effective splitting of CO2 and H2O was achieved at the relatively low temperature of <1000 °C. A synthesis gas production rate of 1.3 mL min–1cm–2 was obtained at 930 °C for a H2O/CO2 feed ratio of 5:1 with a H2O conversion of above 1.7% and a CO2 conversion of above 4.2%. Compared with the discontinuous two-step thermochemical decomposition, the combination of solar energy, catalytic thermolysis, and oxygen transport membrane reactor as proposed in this work offers a new perspective and an alternative route to convert H2O and CO2 into synthesis gas.