Preparation of ZIF-78/ZnO membranes and their application in gasoline vapor recovery

ZIF-78 membranes were prepared on ZnO supports (zinc source) via a reactive seeding synthesis method, and XRD, TGA and SEM were employed to characterize the synthesized powder and membranes. The prepared ZIF-78/ZnO membranes were applied for gasoline vapor recovery, and the effects of operating pressure and temperature, feed concentration and cutting aspect ratio on the separation performance of the ZIF-78 membranes were investigated. The results show that the separation factor increases with the increase of feed concentration, and it reaches maximum under conditions of feed pressure 0.06 MPa, operating temperature 20℃ and cutting aspect ratio 0.2. The permeability of the membrane increases with the increase of operating pressure, feed concentration, operating temperature and cutting aspect ratio. (C5~C7)/N₂ mixtures were used as the model for evaluating membrane performance under different operating pressures. At 20℃, the separation factors of the membrane for n-C₅H₁₂/N₂, n-C₆H₁₄/N₂ and n-C₇H₁₆/N₂ are 2.45, 2.27 and 2.13 respectively, with corresponding permeability of 9.20×10^-8, 6.22×10^-8 and 3.96×10^-8 mol·(m²·s·Pa)^-1 at a feeding pressure of 0.06 MPa and alkane volume fraction of 30 %(V).