CO2-stable Ce0.9Gd0.1O2−δ-perovskite dual phase oxygen separation membranes and the application in partial oxidation of methane to syngas

- Universal stability in CO2 of CGO-perovskite dual phase membranes was demonstrated.
- Good performance of partial oxidation of methane was achieved in a membrane reactor.
- No performance degradation was observed with pure CH4 as reactant in long-term test.

To improve the chemical stability of perovskite materials (alkaline earth metal containing) in CO2-containing atmosphere, based on the dual phase structure membranes, we prepared three CO2-stable CGO (Ce0.9Gd0.1O2−δ)-perovskite dual phase membranes, which takes the perovskite oxides as the electrons conducting phase and the fluorite CGO oxide (possesses inherently high chemical stability against CO2) as the oxygen ionic conductor. During the oxygen separation tests, all the membranes exhibit good reversibility when periodically changing the sweep gases from CO2 to Helium and good long-term stability in CO2, which demonstrate these CGO-perovskite dual phase membranes possess universal stability in CO2. Then one of these dual phase membranes (Ce0.9Gd0.1O2−δ-Ba0.5Sr0.5Co0.8Fe0.2O3−δ (CGO-BSCF)) was chosen as a model material to be applied in partial oxidation of methane (POM) to syngas. At 900 °C, the oxygen permeation flux of 14 mL/min cm2, CH4 conversion of 96% and CO selectivity of 97%, and the H2/CO of 2 were achieved. And no performance degradation of the membrane reactor was observed during continuously 230 h operation by using pure CH4 for POM at 900 °C. Due to the good CO2 stability and good performance in POM, the CGO-perovskite dual phase membranes could potentially stimulate their applications in industrial applications.

Three type CGO-perovskite dual phase membranes were prepared to demonstrated their universal stability in CO2. Then one model material (Ce0.9Gd0.1O2−δ-Ba0.5Sr0.5Co0.8Fe0.2O3−δ) was chosen as a dual phase membrane reactor to be applied in partial oxidation of methane (POM) to syngas. At 900 °C, the oxygen permeation flux of 14 mL/min cm2, CH4 conversion of 96% and CO selectivity of 97% were achieved. And no performance degradation of the membrane reactor was observed during continuously 230 h operation by using pure CH4 for POM at 900 °C, which indicates that the CGO-perovskite dual phase membranes can be steadily operated in POM process with good performance.64