High performance MFI-type zeolite membrane was successfully prepared in ultradilute solution(H_2O/SiO_2= 1000) on inexpensive and macroporous α-Al_2O_3 tubular support by secondary growth.Influences of seed size and H_2O/SiO_2 on morphology and pervaporation performance of the zeolite membranes were investigated.Results showed that the seed layer prepared with 0.4 μm seeds had higher crystal nucleus density which could increase the amount of the nucleation site on the support surface,resulting in a stronger...