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Enhanced H 2 Separation through Mixed Proton–Electron Conducting Membranes Based on La 5.5 W 0.8 M 0.2 O 11.25− δ
Author(s) -
Escolastico Sonia,
Seeger Janka,
Roitsch Stefan,
Ivanova Mariya,
Meulenberg Wilhelm A.,
Serra José. M.
Publication year - 2013
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201300091
Subject(s) - membrane , conductivity , analytical chemistry (journal) , doping , stoichiometry , proton , materials science , oxide , electrochemistry , chemical stability , permeation , chemistry , electrode , chromatography , physics , biochemistry , optoelectronics , organic chemistry , quantum mechanics , metallurgy
La 5.5 WO 11.25− δ is a proton‐conducting oxide that shows high protonic conductivity, sufficient electronic conductivity, and stability in moist CO 2 environments. However, the H 2 flows achieved to date when using La 5.5 WO 11.25− δ membranes are still below the threshold for practical application in industrial processes. With the aim of improving the H 2 flow obtained with this material, La 5.5 WO 11.25− δ was doped in the W position by using Re and Mo; the chosen stoichiometry was La 5.5 W 0.8 M 0.2 O 11.25− δ . This work presents the electrochemical characterization of these two compounds under reducing conditions, the H 2 separation properties, as well as the influence of the H 2 concentration in the feed stream, degree of humidification, and operating temperature. Doping with both Re and Mo enabled the magnitude of H 2 permeation to be enhanced, reaching unrivaled values of up to 0.095 mL min −1 cm −2 at 700 °C for a La 5.5 W 0.8 Re 0.2 O 11.25− δ membrane (760 μm thick). The spent membranes were investigated by using XRD, SEM, and TEM on focused‐ion beam lamellas. Furthermore, the stability in CO 2 ‐rich and H 2 S‐containing atmospheres was evaluated, and the compounds were shown to be stable in the atmospheres studied.