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Abstract: An oxygen transport membrane made from La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF6428) has been tested for air separation by oxygen permeation at 900°C with the introduction of sulfur in the form of hydrogen sulfide. 200ppm of hydrogen sulfide was fed either in the sweep-side (argon-side) or the air-side. The membrane was exposed to hydrogen sulfide for 100h. Results show that the presence of hydrogen sulfide negatively influenced the oxygen permeation due to the formation of strontium sulfate blocking the oxygen permeation pathway. When the hydrogen sulfide was removed from the system, the oxygen permeation was partially restored in the case of argon-side contamination, while being fully restored in the case of air-side contamination. [Copyright &y& Elsevier]

Abstract: The use of wireless electrochemical promotion of catalysis (EPOC) of a Pt catalyst supported on a mixed ionic electronic conducting hollow fibre membranes is investigated. This reactor configuration offers high surface areas per unit volume and is ideally suited for scaled-up applications. The MIEC membrane used is the La0.6Sr0.4Co0.2Fe0.8O3 perovskite (LSCF) with a Pt catalyst film deposited on the outer surface of the LSCF membrane. Experimental results showed that after initial catalyst deactivation (in the absence of an oxygen chemical potential difference across the membrane) the catalytic rate can be enhanced by using an oxygen sweep and wireless EPOC can be used for the in situ regeneration of a deactivated catalyst. [Copyright &y& Elsevier]

Abstract: The mixed conducting perovskite-type La0.8Sr0.2Co1− y MnyO3±δ family has been synthesised by a combinatorial method. This system including the two end member materials (y=0 and 1) have been studied using temperature programmed methods in order to relate structure and composition to oxygen exchange under a hydrogen atmosphere. Oxygen is removed in two steps: firstly, labile surface oxygen from 350 to 450°C and then more strongly bound lattice oxygen. A relationship between the B-site manganese and cobalt content and ease of removal of lattice oxygen was demonstrated over the temperature range of 600–820°C. Removal of labile surface oxygen was independent of the B-site composition but associated with A-site cations on the external surface of the crystallites. [Copyright &y& Elsevier]

Abstract: Dense ceramics with mixed protonic–electronic conductivity are of considerable interest for the separation and purification of hydrogen and as electrochemical reactors. In this work, the hydrogen permeability of a Sr0.97Ce0.9Yb0.1O3− δ (SCYb) membrane with a porous Pt catalytic layer on the hydrogen feed-exposed side has been studied over the temperature range 500–804 °C employing Ar as the permeate sweep gas. A SiO2–B2O3–BaO–MgO–ZnO-based glass-ceramic sealant was successfully employed to seal the membrane to the dual-chamber reactor. After 14 h of exposure to 10% H2:90% N2 at 804 °C, the H2 flux reached a maximum of 33 nmol cm−2 s−1, over an order of magnitude higher than that obtained on membranes of similar thickness without surface modification. The permeation rate then decreased slowly and moderately on annealing at 804 °C over a further 130 h. Thereafter, the flux was both reproducible and stable on thermal cycling in the range 600–804 °C. The results indicate an important role of superficial activation processes in the flux rate and suggest that hydrogen fluxes can be further optimised in cerate-based perovskites. [Copyright &y& Elsevier]