High-precision diffusion measurement of ethane and propane over SAPO-34 zeolites for methanol-to-olefin process

Research Article

Abstract

The methanol-to-olefin (MTO) process has attracted much attention and many problems including lifetime and selectivity of light olefins have all been connected to the diffusion problems in zeolite crystals. However, a quantitative study of diffusion problems in SAPO-34 zeolites is lacking. In this paper, we performed a high-precision diffusion measurement of the diffusion behavior of ethane and propane, which represent ethylene and propylene respectively, over SAPO-34. The diffusions of ethane and propane over fresh and coked SAPO-34 zeolites with different crystal sizes were carefully studied. Ethane and propane show different diffusion behavior in SAPO-34. The diffusion of ethane is almost not influenced by the crystal size and coke percentage, whereas that of propane is strongly affected. A slower diffusion velocity was observed in bigger crystals, and the diffusion velocity decline significantly with the coke percentage increasing. The diffusion coefficient was calculated with both the internal and surface diffusion models, and the results show that the surface diffusion plays a key role in the diffusion process of both ethane and propane. We believe that this work would be helpful for understanding the diffusion of different molecules in SAPO-34 zeolites, and may lay the foundation of MTO research.

Keywords

diffusion measurement methanol-to-olefin process 

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References

  1. 1.
    Su D S, Wen G, Wu S, Peng F, Schlögl R. Carbocatalysis in liquidphase reactions. Angewandte Chemie International Edition, 2017, 56(4): 936–964CrossRefGoogle Scholar
  2. 2.
    Losch P, Pinar A B, Willinger M G, Soukup K, Chavan S, Vincent B, Pale P, Louis B. H-ZSM-5 zeolite model crystals: Structurediffusion-activity relationship in methanol-to-olefins catalysis. Journal of Catalysis, 2017, 345: 11–23CrossRefGoogle Scholar
  3. 3.
    Liang T, Chen J, Qin Z, Li J, Wang P, Wang S, Wang G, Dong M, Fan W, Wang J. Conversion of methanol to olefins over H-ZSM-5 zeolite: Reaction pathway is related to the framework aluminum siting. ACS Catalysis, 2016, 6(11): 7311–7325CrossRefGoogle Scholar
  4. 4.
    Fickel D W, Sabnis K D, Li L, Kulkarni N, Winter L R, Yan B, Chen J G. Chloromethane to olefins over H-SAPO-34: Probing the hydrocarbon pool mechanism. Applied Catalysis A, General, 2016, 527: 146–151CrossRefGoogle Scholar
  5. 5.
    Li Y, Zhang M, Wang D, Wei F, Wang Y. Differences in the methanol-to-olefins reaction catalyzed by SAPO-34 with dimethyl ether as reactant. Journal of Catalysis, 2014, 311: 281–287CrossRefGoogle Scholar
  6. 6.
    Li J, Wei Y, Liu G, Qi Y, Tian P, Li B, He Y, Liu Z. Comparative study of MTO conversion over SAPO-34, H-ZSM-5 and H-ZSM-22: Correlating catalytic performance and reaction mechanism to zeolite topology. Catalysis Today, 2011, 171(1): 221–228CrossRefGoogle Scholar
  7. 7.
    Sun X, Mueller S, Shi H, Haller G L, Sanchez-Sanchez M, van Veen A C, Lercher J A. On the impact of co-feeding aromatics and olefins for the methanol-to-olefins reaction on HZSM-5. Journal of Catalysis, 2014, 314: 21–31CrossRefGoogle Scholar
  8. 8.
    Sun X, Mueller S, Liu Y, Shi H, Haller G L, Sanchez-Sanchez M, van Veen A C, Lercher J A. On reaction pathways in the conversion of methanol to hydrocarbons on HZSM-5. Journal of Catalysis, 2014, 317: 185–197CrossRefGoogle Scholar
  9. 9.
    Ilias S, Bhan A. Mechanism of the catalytic conversion of methanol to hydrocarbons. ACS Catalysis, 2013, 3(1): 18–31CrossRefGoogle Scholar
  10. 10.
    Zhou H, Wang Y, Wei F, Wang D, Wang Z. Kinetics of the reactions of the light alkenes over SAPO-34. Applied Catalysis A, General, 2008, 348(1): 135–141CrossRefGoogle Scholar
  11. 11.
    Li M, Wang Y, Bai L, Chang N, Nan G, Hu D, Zhang Y, Wei W. Solvent-free synthesis of SAPO-34 nanocrystals with reduced template consumption for methanol-to-olefins process. Applied Catalysis A, General, 2017, 531: 203–211CrossRefGoogle Scholar
  12. 12.
    Wu X C, Abraha M G, Anthony R G. Methanol conversion on SAPO-34: Reaction condition for fixed-bed reactor. Applied Catalysis A, General, 2004, 260(1): 63–69CrossRefGoogle Scholar
  13. 13.
    Wei Y, Li J, Yuan C, Xu S, Zhou Y, Chen J, Wang Q, Zhang Q, Liu Z. Generation of diamondoid hydrocarbons as confined compounds in SAPO-34 catalyst in the conversion of methanol. Chemical Communications, 2012, 48(25): 3082CrossRefGoogle Scholar
  14. 14.
    Li Y, Huang Y, Guo J, Zhang M, Wang D, Wei F, Wang Y. Hierarchical SAPO-34/18 zeolite with low acid site density for converting methanol to olefins. Catalysis Today, 2014, 233: 2–7CrossRefGoogle Scholar
  15. 15.
    Wei Z, Chen Y, Li J, Wang P, Jing B, He Y, Dong M, Jiao H, Qin Z, Wang J, et al. Methane formation mechanism in the initial methanolto-olefins process catalyzed by SAPO-34. Catalysis Science & Technology, 2016, 6(14): 5526–5533CrossRefGoogle Scholar
  16. 16.
    Xu S, Zheng A, Wei Y, Chen J, Li J, Chu Y, Zhang M, Wang Q, Zhou Y, Wang J, et al. Direct observation of cyclic carbenium ions and their role in the catalytic cycle of the methanol-to-olefin reaction over chabazite zeolites. Angewandte Chemie International Edition, 2013, 52(44): 11564–11568CrossRefGoogle Scholar
  17. 17.
    Qi L, Li J, Wei Y, Xu L, Liu Z. Role of naphthalene during the induction period of methanol conversion on HZSM-5 zeolite. Catalysis Science & Technology, 2016, 6(11): 3737–3744CrossRefGoogle Scholar
  18. 18.
    Wei Y, Yuan C, Li J, Xu S, Zhou Y, Chen J, Wang Q, Xu L, Qi Y, Zhang Q, Liu Z. Coke formation and carbon atom economy of methanol-to-olefins reaction. ChemSusChem, 2012, 5(5): 906–912CrossRefGoogle Scholar
  19. 19.
    Tian P, Wei Y, Ye M, Liu Z. Methanol to olefins (MTO): From fundamentals to commercialization. ACS Catalysis, 2015, 5(3): 1922–1938CrossRefGoogle Scholar
  20. 20.
    Chen D, Rebo H P, Moljord K, Holmen A. Methanol conversion to light olefins over SAPO-34. Sorption, diffusion, and catalytic reactions. Industrial & Engineering Chemistry Research, 1999, 38 (11): 4241–4249CrossRefGoogle Scholar
  21. 21.
    Aguayo A T, Del Campo A, Gayubo A G, Tarrio A, Bilbao J. Deactivation by coke of a catalyst based on a SAPO-34 in the transformation of methanol into olefins. Journal of Chemical Technology and Biotechnology (Oxford, Oxfordshire), 1999, 74 (4): 315–321CrossRefGoogle Scholar
  22. 22.
    Hwang A, Prieto-Centurion D, Bhan A. Isotopic tracer studies of methanol-to-olefins conversion over HSAPO-34: The role of the olefins-based catalytic cycle. Journal of Catalysis, 2016, 337: 52–56CrossRefGoogle Scholar
  23. 23.
    Yang G, Wei Y, Xu S, Chen J, Li J, Liu Z, Yu J, Xu R. Nanosizeenhanced lifetime of SAPO-34 catalysts in methanol-to-olefin reactions. Journal of Physical Chemistry C, 2013, 117(16): 8214–8222CrossRefGoogle Scholar
  24. 24.
    Zhu W, Kapteijn F, Moulijn J A, den Exter M C, Jansen J C. Shape selectivity in adsorption on the all-silica DD3R. Langmuir, 2000, 16 (7): 3322–3329CrossRefGoogle Scholar
  25. 25.
    Olson D H, Camblor M A, Villaescusa L A, Kuehl G H. Light hydrocarbon sorption properties of pure silica Si-CHA and ITQ-3 and high silica ZSM-58. Microporous and Mesoporous Materials, 2004, 67(1): 27–33CrossRefGoogle Scholar
  26. 26.
    Cui Y, Zhang Q, He J, Wang Y, Wei F. Pore-structure-mediated hierarchical SAPO-34: Facile synthesis, tunable nanostructure, and catalysis applications for the conversion of dimethyl ether into olefins. Particuology, 2013, 11(4): 468–474CrossRefGoogle Scholar
  27. 27.
    Bhatia S K, Perlmutter D D. A random pore model for fluid-solid reactions: II. Diffusion and transport effects. AIChE Journal. American Institute of Chemical Engineers, 1981, 27(2): 247–254CrossRefGoogle Scholar
  28. 28.
    Thiele E W. Relation between catalytic activity and size of particle. Industrial & Engineering Chemistry, 1939, 31(7): 916–920CrossRefGoogle Scholar

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© Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical EngineeringTsinghua UniversityBeijingChina

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