Electrical conduction and hydrogen permeation investigation on iron-doped barium zirconate membrane

• Combined electrochemical and permeation study of BaZr0.90Fe0.10O3−δ (BZF10).
• Bulk diffusion was the rate-limiting step in the thickness range of 0.97–1.40 mm.
• Two activation energies were obtained corresponding to high and low temperatures.
• Under exposure to >0.3 atm moisture, H2 permeation was promoted.
• BZF10 was chemically and mechanically stable over all permeation tests.

Mixed conducting 10% Fe-doped BaZrO3 (BZF10) membrane was investigated for electrical conduction and hydrogen permeation properties in the temperature range of 600–900 °C. A hydrogen permeation flux (JH2)(JH2) as high as 0.75 mL/(min cm2) was achieved at 900 °C using a 1.15 mm thick BZF10 membrane when 20% H2/inert and Ar were flowed in the feed and sweep, respectively. JH2JH2 increases monotonically with the reciprocal of the membrane thickness, indicating bulk diffusion is the rate-limiting step in the examined thickness range (0.97–1.40 mm). At constant temperature, JH2JH2 increases with the feed side hydrogen partial pressure. In the range of 600–700 °C, hydrogen permeation is limited by the electronic transport with high activation energy 72–94 kJ/mol. While in the higher temperature range of 700–900 °C, hydrogen permeation is limited by the mixed protonic-electronic transport with low activation energy 18–23 kJ/mol. The addition of moisture did not influence JH2JH2 when the steam level was below 0.1 atm. While when the steam level reached 0.3 atm, hydrogen permeation process was promoted by the formation of extra protons. BZF10 membrane is found to be mechanically and chemically stable over dry and humidified hydrogen containing gas environments.