Promotion Effect of Steam on Hydrogen and Oxygen Separation in Electrochemical Membrane Reactor: Investigation Under the Aromatization Reaction Temperature Window

Methane aromatization mainly proceeds at 650–750 °C. Simultaneous separation of hydrogen and oxygen can boost conversion efficiency and mitigate catalyst coking, yet most non-electrochemical membrane reactors fail to achieve synchronous hydrogen–oxygen separation within this temperature range. Accordingly, an electrochemical membrane reactor is adopted in this work, and steam is introduced to improve gas separation efficiency. BZCY hollow fiber membranes with mixed proton and oxygen ion conductivity are selected as the research material, and the influences of three distinct steam feeding modes (anode side only, cathode side only, simultaneous feeding on both sides) on H₂ and O₂ permeation and separation are systematically investigated. Experimental results reveal that steam humidification significantly enhances the permeation fluxes of hydrogen and oxygen. Notably, such promotional effect strongly depends on the steam feeding location. At 700 °C and 1.5 V, the hydrogen permeation flux increases to 1.469 mL⋅min⁻¹⋅cm⁻², in sharp contrast to 0.189 mL⋅min⁻¹⋅cm⁻² under dry atmosphere. Meanwhile, the oxygen permeation flux reaches 0.824 mL⋅min⁻¹⋅cm⁻² at 700 °C with steam, which is approximately four times that under dry conditions. This study verifies the intrinsic H₂ and O₂ permeation capability of electrochemical membrane reactors and the remarkable promotion effect originating from steam, facilitating further practical applications of such membrane reactors in methane aromatization.