Facile hydrogen/nitrogen separation through graphene oxide membranes supported on YSZ ceramic hollow fibers

Abstract

From the early of 1990s, intensive research has been started to seek a possible more efficient gas separation using inorganic membranes with more hopes on zeolite membrane. Although prohibitive difficulties have been encountered, our enthusiasm or imagination has never been quenched out, particular with the modern era of “magic” material-graphene. In this work, we explored the possibility of using supported graphene oxide (GO) membrane for gas separation. For this purpose, the porous YSZ hollow fiber ceramic support and GO flakes with size up to 5 µm were separately prepared; subsequently, vacuum-suction impregnation was applied to assemble the GO laminates on the fiber external surface with the thickness of 230 nm. The 2D nano-channels formed by the two neighboring one-atom-thick GO layers endow the membrane with molecular-sieving function. Gas permeation behavior was investigated by the measurement of gas permeances from the single gas components and the gas mixture (H2/N2). The ideal selectivity of H2/N2 at 20 oC was up to 76, mirroring the molecular sieving function via molecular size limited diffusion and preferable adsorption. Compared to the ideal selectivity, the H2/N2 separation factor is lower due to the blocking effect of the other components. At higher temperature, N2 permeance was increased by a percentage more than that of H2 thus decreasing the separation factor from 68 (20 oC) to 37 (100 oC). The H2 separation test for 240 h highlights stable performance in maintaining the separation factor and the permeance. H2 permeation using GO/YSZ hollow fiber was also theoretically probed. Simulation implies that in achieving the overall H2 permeance, the front part (near the inlet) of the hollow fiber makes much more contribution than the rear part. To more effectively use the GO hollow fiber, the feed gas pressure can be increased or the vacuum pressure can be applied in the permeate side.