Chem. J. Chinese Universities ›› 2026, Vol. 47 ›› Issue (10): 20260245.doi: 10.7503/cjcu20260245

• Physical Chemistry • Previous Articles     Next Articles

Theoretical Study of the Influence of H-SAPO-34 Modified with Zn2+ on Olefin-based Cycles During Methanol-to-olefins Reaction

GAO Fen’e1(), WANG Ruiying1, GUO Junlan1, ZHANG Xi1, CHENG Shangyuan2, YUAN Zhiguo2(), LIU Jingyao3()   

  1. 1.College of Energy Engineering,Shanxi College of Technology,Shuozhou 036000,China
    2.Shanxi Province Key Laboratory of Chemical Process Intensification,North University of China,Taiyuan 030051,China
    3.Institute of Theoretical Chemistry,College of Chemistry,Jilin University,Changchun 130023,China
  • Received:2026-06-23 Online:2026-10-10 Published:2026-09-03
  • Contact: GAO Fen’e, YUAN Zhiguo, LIU Jingyao E-mail:gaofene@sxct.edu.cn;ncustyzg@nuc.edu.cn;ljy121@jlu.edu.cn
  • Supported by:
    the Scientific and Technological Innovation Programs of Higher Education Institutions of Shanxi Province, China(2024L437);the Open Project of Shanxi Province Key Laboratory of Chemical Process Intensification, China(2024-CPI10);the Doctoral Research Start-up Funds of Shanxi College of Technology, China(022015)

Abstract:

The reaction mechanisms of the olefin‑based cycles for ethene and propene formation at Brønsted acid sites(BAS) in H‑SAPO‑34 and at BAS and Lewis acid sites(LAS) in Zn@H‑SAPO‑34 were systematically investigated by means of density functional theory(DFT) calculations combined with microkinetic simulations, with the aim of elucidating the influence of Zn2+ modification on the catalytic performance of the methanol‑to‑olefins(MTO) reaction. The results demonstrate that the selectivity to propene based on the olefin-based cycle catalyzed by H-SAPO-34 is higher than that to ethene(consistent with the previous reports). The Zn2+ modification enhances the acidic strength of neighbouring BAS, significantly reducing the overall free energy barriers for both the ethene and propene formation pathways and improving activity. It also decreases the difference in their barriers. At LAS, the overall free energy barrier for ethene formation has been found to be slightly lower than that for propene, indicating a relative selectivity advantage toward ethene; however, both barriers are significantly higher than those at BAS, suggesting that LAS are not the dominant active sites. Further microkinetic simulations show that BAS remain the main active sites after Zn2+ modification, with total turnover frequencies(TOF) increased by 2—3 orders of magnitude compared to unmodified H‑SAPO‑34. The propene selectivity advantage is kept and the relative selectivity towards ethene increases with rising temperature. In summary, the enhancement of B-acid strength and the introduction of LAS by Zn2+ modification improve the overall catalytic activity while maintaining the propene selectivity advantage and reducing the selectivity difference between ethene and propene. This work provides theoretical guidance for the rational design of high‑performance MTO catalysts.

Key words: Zn2+-modified H-SAPO-34, Density functional theory, Methanol?to?olefins(MTO), Olefin-based cycle

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