Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (10): 907-912.doi: 10.3866/PKU.WHXB20031005

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Hydrothermally Stable Mesoporous Aluminosilicates with Strongly Acidic Sites

Zheng Jun-Lin;Zhang Ye;Wei Wei; Wu Dong;Sun Yu-Han;Deng Feng;Luo Qing;Yue Yong   

  1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001;State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071
  • Received:2003-03-24 Revised:2003-05-27 Published:2003-10-15
  • Contact: Sun Yu-Han

Abstract: Mesoporous aluminosilicates were synthesized through S+X-I+ route using preformed β zeolitic nanoclusters as building units in acidic media and subsequent ammonia hydrothermal treatment. The ordered mesoporous aluminosilicates were characterized by XRD, N2 adsorption and desorption, HRTEM, SEM, NMR and NH3-TPD methods. The results indicated that the sample had the same hexagonal mesostructures as normal MCM-41 synthesized in acidic media. The presence of strongly acidic sites was substantiated by NH3-TPD study, and the hexagonal mesoporous structure was maintained even after 120 h treatment in boiling water. The synthesized materials were superior to conventional MCM-41 with respect to their stronger acidity and higher hydrothermal stability. The short period of assembly in acidic media and the ambient temperature reduced the dealumination effect considerably. The retention of zeolite-like connectivity of tetrahedral AlO4 and SiO4 units upon assembling the nanoclusters into mesostructured materials and the thicker framework pore walls contributed to the especially good hydrothermal stability greatly, which also gave rise to the presence of strong acidity.

Key words: Mesoporous molecular sieves, Acidity, Hydrothermal stability, SXI route