Novel Cobalt-Free, Noble Metal-Free Oxygen-Permeable 40Pr_0.6Sr_0.4FeO_3-δ–60Ce_0.9Pr_0.1O_2−δ Dual-Phase Membrane

Abstract

A novel cobalt-free and noble metal-free dual-phase oxygen-transporting membrane with a composition of 40 wt % Pr0.6Sr0.4FeO3−δ–60 wt % Ce0.9Pr0.1O2−δ (40PSFO–60CPO) has been successfully developed via an in situ one-pot one-step glycine-nitrate combustion process. In situ XRD demonstrated that the 40PSFO–60CPO dual-phase membrane shows a good phase stability not only in air but also in 50 vol % CO2/50 vol % N2 atmosphere. When using pure He or pure CO2 as sweep gases, at 950 °C steady oxygen permeation fluxes of 0.26 cm3 min–1 cm–2 and 0.18 cm3 min–1 cm–2 are obtained through the 40PSFO–60CPO dual-phase membrane. The partial oxidation of methane (POM) to syngas was also successfully investigated in the 40PSFO–60CPO dual-phase membrane reactor. Methane conversion was found to be higher than 99.0% with 97.0% CO selectivity and 4.4 cm3 min–1 cm–2 oxygen permeation flux in steady state at 950 °C. Our dual-phase membrane - without any noble metals such as Ag, Pd or easily reducible metals oxides of Co or Ni - exhibits high oxygen permeation fluxes as well as good phase stability at high temperatures. Furthermore, the dual-phase membrane shows a good chemical stability under the harsh conditions of the POM reaction and in a CO2 atmosphere at high temperatures.