Using MAS NMR method to determine the geometry of the Bronsted acid, the distribution of aluminium atoms in ZSM-5 and ZSM-5/MCM-41.

  • Lê Thị Hoài Nam
  • Nguyễn Đình Tuyến
  • Nguyễn Trọng Hưng
  • Nguyễn Ngọc Trìu


Z5M-5/MCM-41 composite was prepared by using a dual-template synthetic get svstern Tetrapropylamoniumhydroxit TPAOH and cetyltritmetylamoniumbromide CTMAB. The structure of that material was investigated by IR, XRD, TEM, and TPD-NH3, and nitrogen adsorption/desorption [1]. The results of IR, XRD, NMR showed that the most of aluminum atoms distributed in the framework. In this paper, 27Al, 1H MAS NMR are used to determine the geometry of the Bronsted acid and the distribution of aluminum atoms in ZSM-5/MCM-41. Acidic(-bridging-) OH groups in ZSM-5/MCM-41 are responsible for the catalytic activity. They can exist ill materials infourfonns: SiOHAl (δ= 4,1 ppm), AlOH (δ = 2.7ppm), SiOH1 (δ = 1,8 ppm), and SiOH2 (δ = 2.2 ppm). Here, we call see the differences of acidities between ZSM-5 and ZSM5-/MCM-41 base on the signals of the formation of bridging OH groups (SiOHAl)

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