Hydrogen separation by Pd–CaZr₀.₉Y₀.₁O₃₋δ cermet composite membranes

• Published in: Separation and purification technology 2011-06, Vol.79 (3), p.337-341
• Main Authors: Jeon, S.-Y, Lim, D.-K, Choi, M.-B, Wachsman, E.D, Song, S.-J
• Format: Article
• Language: English
• Subjects: Applied sciences; carbon dioxide; ceramics; Chemical engineering; energy; Exact sciences and technology; gases; hydrogen; permeability; temperature; thermodynamics
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2011.03.018

A cermet composite membrane composed of a hydrogen-transporting metal (Pd) embedded in a thermodynamically stable, proton-conducting, ceramic matrix (CaZr₀.₉Y₀.₁O₃₋δ) was proposed to achieve the successful combination of high permeability and chemical stability in a CO₂-containing atmosphere at elevated temperatures (>600°C). The influence of both applied hydrogen chemical potential gradient and temperature on the hydrogen permeation properties of 0.5-mm-thick, Pd–CZY cermet membranes were studied using dry feed gases with 20–80% H₂. The hydrogen permeation flux increased from 1.3 to 2.3cm³(STP)/min-cm² with increasing temperature and [Formula: see text] gradient. The effect of the ceramic matrix on the permeability of the Pd–cermet membranes was also compared. The proton-conducting ceramic matrix exhibited the maximum hydrogen permeation flux, which was attributed to the additional ambipolar hydrogen permeation through the cermet membrane. Finally, the hydrogen permeability in CO₂-containing gas streams was investigated using a dry feed gas stream comprised of 30% CO₂, 20% H₂ and 50% He. The decrease in hydrogen permeation flux with increasing temperature was ascribed to the decrease in the H₂ content in the feed gas stream as calculated using the Gibbs energy minimization method.