Perfluorooctanol-based liquid membranes for H2/O2 separation

Hydrogen is an important substance in the chemical industry which can be generated by different methods, including photocatalytic water splitting. Photocatalysis is an environmentally friendly technique to generate H-2, but produces it in a mixture with O-2. This paper reports the use of a perfluorooctanol-based liquid membrane to separate the gases. The membrane shows an excellent separation performance at room temperature with an average H-2/O-2 selectivity of 100 with a H-2 flux of 2.9 x 10(-10) mol m(-2) s(-1) Pa-1 (1030 barrers) for a 50/50 mixed gas feed. The separation was tested at various operating conditions, and it was found that higher temperatures and flow rates did not affect considerably the performance of the membrane, but decreased its stability. The diffusivity and solubility of H-2 and O-2 in the perfluorooctanol membrane were measured by a time-lag technique, resulting in diffusivities of 1.4 x 10(-4) and 3.2 x 10(-5) cm(2) s(-1) and solubilities of 4.4 x 10(-4) and 5.4 x 10(-4) mol m(-3) Pa-1 for H-2 and O-2, respectively. The membrane was tolerant of water, but increase in hydrogen partial pressure decreased permeance. (C) 2013 Elsevier B.V. All rights reserved.