Hydrogen permeation and chemical stability of In-doped SrCe0.95Tm0.05O3−δ membranes

A series of SrCe0.95−xInxTm0.05O3−δ (x = 0.00, 0.05, 0.10, 0.15, 0.20) samples were prepared by the sol-gel technique using ethylenediaminetetraacetic acid and citric acid as the complexing agents. The X-ray diffraction (XRD) measurements were carried out to study the formation of SrCe0.75In0.20Tm0.05O3−δ oxide. The results indicate that In can dissolve in the orthorhombic lattice of strontium cerate to form a solid solution at 1300 °C. The effects of In doping on the sinterability, chemical stability and hydrogen permeation flux of SrCe0.95Tm0.05O3−δ oxides were investigated by a variety of characterization methods. According to the results of XRD and scanning electron microscopy (SEM), increasing In content in the oxides causes lattice constriction and promotes grain growth during sintering process at 1300 °C. The relative density and morphology variation of the sintered membranes reveals that In doping improves the sintering activity of SrCe0.95Tm0.05O3−δ membrane. The stability test shows that the stability of strontium cerate against CO2 increases with the increasing In content. Hydrogen permeation through the SrCe0.95−xInxTm0.05O3−δ membranes was carried out between 700 and 900 °C using 40% H2/He mixture as feed gas and Ar as sweep gas, respectively. The H2 permeation flux decreases with the increase of the In content. Activation energies of SrCe0.95Tm0.05O3−δ, SrCe0.85In0.10Tm0.05O3−δ and SrCe0.75In0.20Tm0.05O3−δ are 36.61, 52.25 and 73.06 kJ/mol, respectively.