Syngas Production by Biogas Reforming in a Redox-Stable and CO2-Tolerant Oxygen Transporting Membrane Reactor

A novel membrane reactor consisting of Ce0.9Gd0.1O2−δ–Gd0.1Sr0.9Fe0.9Ti0.1O3−δ (CGO–GSFT) is used to combine air separation with biogas reforming in a single unit. The composite material CGO–GSFT was synthesized via a combined EDTA–citrate complexing sol–gel method. Characterization with XRD, SEM, and EDXS revealed that the composite material was a two-phase fluorite–perovskite system with good compatibility and a homogeneous percolative network. XRD demonstrated that the CGO–GSFT membrane shows a good phase stability not only in CO2 but also in simulated biogas atmosphere. Under the gradient of air/simulated biogas, the oxygen permeability and methane conversion was increased by either raising the operating temperature or increasing the CO2 concentration. At 890 °C and a CH4/CO2 molar ratio of 1.5, an oxygen permeation flux of 1.1 cm3 min–1 cm–2 through the CGO–GSFT membrane was achieved while methane conversion reached 83%, and remained stable for nearly 150 h before the measurement was intentionally st...