Hydrogen-permeation characteristics of a SrCeO 3-based ceramic separation membrane: Thermal, ageing and surface-modification effects

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 Sr 0.97Ce 0.9Yb 0.1O 3 − 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 SiO 2–B 2O 3–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% H 2:90% N 2 at 804 °C, the H 2 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.