Chinese Journal of Catalysis ›› 2016, Vol. 37 ›› Issue (2): 227-233.DOI: 10.1016/S1872-2067(15)61025-7

• Communications • Previous Articles     Next Articles

Charge compensation dominates the distribution of silica in SAPO-34

Huiru Zhaoa, Shumei Shia,b, Jinxiong Wua, Yue Dinga, Niu Lia,b   

  1. a Institute of New Catalytic Material Science, School of Materials Science and Engineering, Nankai University, Tianjin 300071, China;
    b National Institute for Advanced Materials, Nankai University, Tianjin 300071, China
  • Received:2015-11-13 Revised:2015-11-23 Online:2016-01-30 Published:2016-01-31
  • Supported by:

    This work was supported by the Natural Science Foundation of Tianjin (12JCYBJC 12700).

Abstract:

The distribution of Si atoms in the SAPO-34 framework determines its acidity and catalytic effects. This was investigated using the charge balance between the inorganic framework and trapped template ions. Three types of templates, which yielded R+, 2R+ and 2R2+ positive charges in the cages of SAPO-34, were obtained from single crystal data and they were used to direct the synthesis of SAPO-34 with different Si contents and formation of isolated Si atoms and Si islands in the lattice. The concentration limits of SiO2 in the gel for constituting isolated Si atoms were calculated and verified experimentally. Si islands, including 5-Si, 8-Si, 11-Si, 14-Si island were described on the basis of host-guest charge compensation. An overall view of the distribution of Si atoms in SAPO-34 was given and a criterion for the strength and density of acid sites in SAPO-34 for it to be an efficient catalyst for MTO was made available.

Key words: SAPO-34, Si distribution, Synthesis, Silicon island, Methanol to olefins