Synthesis and gas permeation properties of silicalite-1 zeolite membrane

Silicalite 1/ceramic composite membrane was prepared on the outer surface of the α Al 2O 3 tubular support by in situ hydrothermal synthesis. The membrane was characterized by X ray diffraction (XRD) and scanning electron microscope (SEM). The pure gas permeances of H 2, N 2, Ar, CH 4, C 2H 4, C 2H 6, C 3H 8, n C 4H 10 and i C 4H 10 were measured as a function of the pressure difference at 298 and 473 K. The permeances of H 2, N 2 and Ar showed little dependence on the pressure differences; the permselectivities of H 2/ i C 4H 10 were 249 and 36.2 at 298 and 473 K respectively, which is a characteristic of molecular transport in silicalite 1 channels. The permeances of light alkanes decreased in the following order: CH 4>C 2H 6>C 3H 8> n C 4H 10 > i C 4H 10 . The permselectivity of n C 4H 10 / i C 4H 10 was above 15 at 298 K. As the temperature increased, the permeances of all gases increased except those of N 2 and Ar, and a significant increment was found for alkanes. The permselectivity of n C 4H 10 / i C 4H 10 decreased to about 9 at 473 K. The gas permeation results showed that the silicalite 1/ceramic composite membrane was defect free.