Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (2): 519-526.doi: 10.3866/PKU.WHXB201511243

• ARTICLE • Previous Articles     Next Articles

Synthesis and Low-Temperature Detemplation of High-Silica MFI Zeolite Membranes

Shu-Heng ZHAO1,2,Lin LANG1,*(),Jun-Fei JIANG1,2,Xiu-Li YIN1,Chuang-Zhi WU1   

  1. 1 CAS Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
    2 University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2015-09-24 Published:2016-01-30
  • Contact: Lin LANG E-mail:langlin@ms.giec.ac.cn
  • Supported by:
    the National Natural Science Foundation of China(51202245, 51106165);Natural Science Foundation ofGuangdong Province, China(S2013010014896, 10251007006000000)

Abstract:

High-silica MFI zeolite membranes supported on porous α-alumina discs were prepared by a seeded secondary growth method, using tetrapropylammonium hydroxide (TPAOH) as organic template. First, nanocrystals were deposited on rough α-Al2O3 discs by a spin-on process. Then, based on controlling the H2O/Si molar ratio of the synthetic solution, a restricting in-plane h0h-oriented growth method with an ultra-dilute precursor was designed to prepare non-defective zeolite membranes that were as thin as possible. Finally, crosslinked and dense MFI zeolite membranes were prepared after the third synthesis step, giving a membrane layer thickness of about 8 μm, including ~5 μm dense layers and ~3 μm intermediate layers. Anovel, two-step method, coupling by low-temperature hydrocracking and oxidation, is proposed for efficient removal of the template from zeolite membranes. Compared with traditional high-temperature calcination, template removal by the two-step method could eliminate the grain boundary defects formed in response to stresses induced by heat treatment. As a result, the membranes treated by the two-step detemplation method displayed a preferable CO2/N2 separation factor (about 5.2) and high CO2 permeance (5.8 × 10-7 mol·m-2·s-11·Pa-1) at 30 ℃.

Key words: High-silica MFI zeolite membrane, Template removal, Low-temperature hydrocracking, Gas permeation, Support

MSC2000: 

  • O647