Tubular zeolite *BEA membrane was prepared by a hydrothermal secondary growth method in the absence of an organic structure directing agent (OSDA). Membrane formation process was carefully observed by using FE-SEM, XRD, and N2 adsorption, and the role of seed crystals on the support surface was discussed. Seed crystals loaded on the outer surface of a tubular porous alumina support partially dissolved and a small amount of seeds remained in an amorphous layer formed on the support surface in the early stage of secondary growth step. Subsequently, crystal growth of remaining crystals occurred, and a continuous *BEA layer was obtained following crystallization for 7 days at 393 K. In the secondary growth step, the supported seed layer played an important role in inducing the formation of a high local concentration in the vicinity of the support surface. The prepared OSDA-free *BEA membrane was then applied in the separation of hydrocarbons. We found that this membrane contained very few defects, and exhibited a high ideal selectivity for cyclohexane/1,3,5-trimethylbenzene mixture of 100, with cyclohexane permeance of 1.0 × 10−7 mol m−2 s−1 Pa−1 based on molecular sieving effect at 623 K.
ASJC Scopus subject areas
- 化学 (全般)