物理化学学报 >> 2001, Vol. 17 >> Issue (09): 811-816.doi: 10.3866/PKU.WHXB20010910

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B、Al、Ga同晶取代丝光沸石的从头计算

袁淑萍;王建国;李永旺;彭少逸   

  1. 中国科学院山西煤炭化学研究所 煤转化国家重点实验室,太原　030001
  • 收稿日期:2001-03-07 修回日期:2001-05-09 发布日期:2001-09-15
  • 通讯作者: 王建国 E-mail:iccjgw@sxicc.ac.cn

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

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摘要： 用从头计算HartreeFock方法研究了B、Al、Ga等同晶取代进入丝光沸石骨架后可能存在的位置，确定了与电荷平衡质子结合的氧位置，考察了B、Ga等杂原子进入骨架对丝光沸石Brnsted酸性的影响.能量分析表明B、Al、Ga在丝光沸石骨架中最容易进入T3和T4位；当Al、Ga在T4位时，质子与O10结合为能量最低即最稳定结构，而当B在T4位时，质子与O2或O10结合比较稳定.质子亲合势分析表明与硅铝丝光沸石相比， B和Ga进入骨架导致丝光沸石分子筛的Brnsted酸性有所减弱，其酸性依次为：BZSM5GaZSM5< AlZSM5.

关键词: B、Al、Ga, 同晶取代, 丝光沸石, 酸性, 从头计算

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