Preparation And Characterization Of Novel Pervoskite-type Mixed Prontonic And Electronic Conducting Membrane

Dense ceramic membranes with protonic and electronic conductivity have been attracting significant attention over the past few decades, due to their potential application in hydrogen-based energy, petrochemical processes, hydrogen separation, hydrogen-air fuel cells and membrane reactors. Membrane materials especially for hydrogen permeation required to be stable at working temperature and in oxygen ambience. In general, cerate-based protonic conductors have a high conductivity but rather poor chemical and thermal stability, which decomposes to SrCO3 and CeO2. In contrast, zirconate-based protonic conductors are stable but have rather low conductivity. The combination of cerate and zirconate may have both high protonic conductivity and good chemical stability. From this point of view, this paper reports Zr-substituted, Tm-doped SrCeO3 to obtain dense ceramic membranes, which has high protonic conductivity and good chemical stability. eation membrane of the mateThe SrCe0.95-xZrxTm0.05O3-δ(x=0.0, 0.1, 0.2, 0.3, 0.4) membranes have been synthesized with Sr(NO3)2, Ce(NO3)3·6H2O, ZrO(NO3)2·2H2O, Tm(NO3)3·6H2O via the EDTA-Citric acid method, and the membranes of SrCe0.95-xZrxTm0.05O3-δwere prepared by pressing followed by sintering. TG-DSC, XRD and SEM-EDS were used to characterize the phase structure and microstructure of precursors , powder and sintered membranes. The total conductivities of SrCe0.95-xZrxTm0.05O3-δ(0≤x≤0.40) were measured by the four point DC method under different atmosphere and temperature(600-900℃). The hydrogen permeation experiments were carried out on the self-made high temperature permeation cell. All tests were conducted with silver seals, and the membranes were sealed within the temperature range of 948-953℃below the melting temperature of silver about 962℃. Zr4+ doping can not only enhance the stability of the materials, but also decrease the electrical conductivity. The total conductivities of SrCe0.75Zr0.20Tm0.05O3-δin air, at 900℃, keep about 0.025 S/cm, stably. Hydrogen permeation flux of SrCe0.75Zr0.20Tm0.05O3-δmembrane can reach up to 0.042 mL/min·cm2 at H2 partial pressure of 0.4 atm. So the SrCe0.75Zr0.20Tm0.05O3-δmembrane can be regarded as the best potential hydrogen permrials.According to the reduction in hydrogen permeation flux, we can reduce the membrane e the devices to offset the reduction in permeation flux which was caused by the doping Zr4+. thickness or improv...