Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (8): 20230063.doi: 10.7503/cjcu20230063

• Physical Chemistry • Previous Articles     Next Articles

Theoretical Calculation of Relationship Between Zeolite Confinement Effect and Adsorbed 2-13C-acetone 13C Chemical Shift

XIONG Wenpeng1,2, CHU Yueying1(), WANG Qiang1(), XU Jun1, DENG Feng1()   

  1. 1.National Center for Magnetic Resonance in Wuhan,State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430071,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2023-02-17 Online:2023-08-10 Published:2023-04-12
  • Contact: CHU Yueying E-mail:chuyueying@wipm.ac.cn;qiangwang@wipm.ac.cn;dengf@wipm.ac.cn
  • Supported by:
    the National Energy R&D Center of Petroleum Refining Technology;the National Natural Science Foundation of China(21991092);the National Key Research and Development Program of China(2022YFB3504001)

Abstract:

The relationship between adsorbed 2-13C-acetone 13C chemical shift and zeolite confinement effect and acid strength(deprotonation energy, DPE) has been assessed by the quantum chemical calculation with the aim of decoupling the influence of acid site strength and zeolite confinement on the measured 13C chemical shift, both of which are key factors in zeolite catalysis. We found the hydrogen-bond complex exist for acetone adsorption independent of the location of the Brønsted acid sites. The calculational results show that although the 13C chemical shift of adsorbed acetone increases with the increase of zeolite intrinsic acid strength(DPE decreasing), but a linear correlation is not present between them. For the Brønsted sites located in the zeolites with different pore sizes, the subtle difference in the DPE values would lead to significant differences in the 13C chemical shift, which demonstrated the zeolite pore confinement played a pivotal role in the measured 13C chemical shift in zeolite catalysis. The acetone adsorption energy increases with the decreasing of the zeolite pore size, which could reflect the strength of the zeolite pore confinement effect. Furthermore, a linear correlation is obtained for the 13C chemical shift of adsorbed acetone versus its adsorption energy, which can be used as a scale for quantitatively measuring the zeolite pore confinement effect.

Key words: Zeolite, Quantum chemical calculation, Confinement effect, Acid strength, Chemical shift

CLC Number: 

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