Methane conversion to syngas and hydrogen in a dual phase Ce0.8Sm0.2O2-δ-Sr2Fe1.5Mo0.5O5+δ membrane reactor with improved stability

Abstract Coupling of partial oxidation of methane (POM) with water dissociation in an oxygen transport membrane is a promising technology for methane utilization. However, cobalt-based membrane materials show poor stability under the above harsh conditions. In this work, a nominal 60 wt % Ce 0.8 Sm 0.2 O 2-δ -40 wt % Sr 2 Fe 1.5 Mo 0.5 O 5+δ (CSO-SFMO) dual phase membrane is reported, which was synthesized by using a one-pot EDTA-citric acid complexing method. The phase structure and morphology of the CSO-SFMO membrane were characterized by XRD, SEM and EDXS. It was found that a uniform distribution of CSO phase with a fluorite structure and SFMO phase with a perovskite structure was achieved in the dual phase membrane. The CSO-SFMO membrane exhibited an improved stability compared with cobalt based perovskite Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ, (BSCF) membrane under CO 2 or reductive gas atmospheres. The oxygen permeation flux of the dual phase membrane was investigated under different oxygen partial pressure gradients: air/He, air/CO 2 , air/POM, and H 2 O/POM. At 950 °C, the oxygen permeation fluxes of the CSO-SFMO membrane under air/POM and H 2 O/POM gradients were 2.7 cm 3 (STP) min −1 cm −2 and 0.75 cm 3 (STP) min −1 cm −2 , respectively, which were much higher than the oxygen flux of 0.1 cm 3 (STP) min −1 cm −2 under air/He. Moreover, a CO selectivity of 98%, a CH 4 conversion of 97% on the POM side and a H 2 production of 1.5 cm 3 (STP) min −1 cm −2 on the H 2 O splitting side were achieved in CSO-SFMO membrane reactor under the oxygen partial pressure gradient of H 2 O/POM, which was steadily run for 100 h before the measurement was intentionally stopped.