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Soft-chemistry routes were used to synthesize Ce0.9Gd0.1O1.95 (CGO) membrane materials with attractive structural, morphological and textural properties. In the intermediate temperature domain between 500°C and 700°C, the average crystallite size is in the range 8–22 nm and the specific surface area varies from 43.4 m2/g to 8 m2/g. The corresponding supported membranes were synthesized by an infiltration method on/in α-Al2O3 tubular supports. The specific surface area of the CGO supported membrane reaches 18.5 m2/g at 700°C, i.e. a higher value than for powders. The gas permeation properties of the membranes were studied up to 500°C. A dispersion of Pt nanoparticles within the membrane material has been also investigated in order to study the role of noble metals in the oxygen transfer from the gas phase to the ceria crystallites (solid/gas interface). Post-impregnation of Pt revealed an adapted synthesis method to enhance surface oxygen transport for the CGO material.

Soft-chemistry routes can yield homogeneous nanophase material consisting of the Ce0.9Gd0.1O1.95 fluorite phase. The method was used for preparing a series of membranes in which the CGO material was infiltrated inside the pores of a tubular alumina support. In order to evidence an activated surface transport for oxygen through this type of membrane, single gas permeance studies, using pure N2 and O2, were performed with the series of infiltrated membranes (Pt-free-CGO, Ptinsol-CGO and PtpostCGO membranes). Results showed that, even under the applied conditions (no sweep gas, O2 on the tube side, atmospheric air on the shell side) specific adsorption and surface diffusion effect can favor the transport of oxygen through a CGO membrane including a dispersion of post-impregnated Pt particles. Other tests focusing on the influence of a sweep gas and of a greater difference in oxygen partial pressure (∆pO2) through the membrane, on the total pressure and on the permeation of gas mixture are also under way with these membranes.