Supported fluorocarbon liquid membranes for hydrogen/oxygen separation

• Perfluorocarbon supported liquid membranes were studied for H2/O2 separation.
• Perfluorodecyl acrylate-based membrane showed the highest performance.
• H2 permeance was 2.4×10−9 mol m−2 s−1 Pa−1 (4500 barrers) and H2/O2 selectivity 10.
• The lifetime of the membrane was over 48 h, much longer than previous.

Photocatalytic water splitting is an environmentally-friendly method for hydrogen formation, but usually H2 and O2, are produced together, so separation is needed. This paper describes the separation of the gases with supported liquid membranes. The permselective liquids were various perfluorocarbon-based fluids, Dimethyl perfluorosebacate ((CF2)6(COOCH3)2), ethyl perfluorononanoate (CF3(CF2)7COOC2H5), perfluoro(perhydrophenanthrene) (C14F24) and 1H,1H,2H,2H-perfluorodecyl acrylate (CF3(CF2)7(CH2)2OCOCH=CH2). It was found that the perfluorodecyl acrylate-based liquid membrane showed the highest performance with H2 permeance of 2.4×10−9 mol m−2 s−1 Pa−1 (6700 barrers) and a H2/O2 selectivity of 10. The permeance properties of H2 and O2 were measured by a time-lag technique and respective diffusivities of 1.1×10−8 and 6.7×10−9 m2 s−1 and solubilities of 2.7×10−4 and 4.1×10−5 mol m−3 Pa−1, were obtained. The lifetime of the membrane was over 48 h, which was much longer than that of other perfluorocarbon-based liquid membranes. The membrane was also stable at humid conditions.

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