Emission of gasoline vapor always existed in the petroleum transportation,processing and usage processes,which would cause serious environmental problems and resources loss [1].Membrane technology is expected to provide a better alternative method.Zeolitic imidazole frameworks (ZIFs),a subfamily of MOFs,have awakened great interest as an active layer of membranes in recent years,due to their hydrothermal and chemical stability [2].ZIF-8 membranes supported on α-alumina discs were prepared by a seeded growth method [3] and the separation performance was evaluated by n-hexane/nitrogen mixture in this study.