Seeded growth of beta zeolite membranes using zeolite structure-directing agent

摘要

In this work, beta zeolite membranes were prepared on seeded α-Al_2O_3 substrate tubes using zeolite structure-directing agent (ZSDA), instead of directly using organic agent as templates. This ZSDA method consists of two steps: preparation of beta ZSDA and growth of beta zeolite membranes with ZSDA by the secondary hydrothermal synthesis. The molar compositions of the synthesis solution of ZSDA and zeolite membrane are of 1SiO_2/0.012Al_2O_3/0.167(TEA)_2O/0.031Na_2O/9.4H_2O and lSiO_2/0.03Al_2O_3/0.027(TEA)_2O/0.27Na_2O/25H_2O, respectively. Preparing the membranes only needed a little ZSDA, which was used to substitute for conventional templates in the secondary growth process of the membrane. The membranes were characterized by SEM, XRD and nitrogen permeance. It was found that the prepared membranes are continuous and defect-free. The mechanism of membrane growth with ZSDA was discussed simply.