Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (09): 811-816.doi: 10.3866/PKU.WHXB20010910

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Ab initio Study on B, Al or Ga Isomorphously Substituted Mordenites

Yuan Shu-Ping;Wang Jian-Guo;Li Yong-Wang;Peng Shao-Yi   

  1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry,Chinese Academy of Sciences, Taiyuan 030001
  • Received:2001-03-07 Revised:2001-05-09 Published:2001-09-15
  • Contact: Wang Jian-Guo E-mail:iccjgw@sxicc.ac.cn

Abstract: The siting of B, Al or Ga and the bridging hydroxyl group in mordenite framework were studied by using ab initio HartreeFock methods. The influence of the presence of B or Ga in the framework on the Bronsted acidity of mordenite was investigated. It was shown that energetically, heteroatoms including B,Al or Ga prefer the same Tsites, T3 and T4, when replacing Si in mordenite framework. For the preferred substitution site T4, the chargecompensating proton prefers to attach to O10 in case of Al and Ga substitution while the proton prefers to bond with O2 or O10 in case of B substitution. The proton affinity calculations showed that the acidity of isomorphously substituted mordenite increases in the order:BMORGaMOR< AlMOR.

Key words: B, Al or Ga, Isomorphous substitution, Mordenite, Acidity, Ab initio