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Effect of temperature and branching on the nature and stability of alkene cracking intermediates in H-ZSM-5

(2017) JOURNAL OF CATALYSIS. 345. p.53-69
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Abstract
Catalytic cracking of alkenes takes place at elevated temperatures in the order of 773–833 K. In this work, the nature of the reactive intermediates at typical reaction conditions is studied in H-ZSM-5 using a complementary set of modeling tools. Ab initio static and molecular dynamics simulations are performed on different C4single bond C5 alkene cracking intermediates to identify the reactive species in terms of temperature. At 323 K, the prevalent intermediates are linear alkoxides, alkene π-complexes and tertiary carbenium ions. At a typical cracking temperature of 773 K, however, both secondary and tertiary alkoxides are unlikely to exist in the zeolite channels. Instead, more stable carbenium ion intermediates are found. Branched tertiary carbenium ions are very stable, while linear carbenium ions are predicted to be metastable at high temperature. Our findings confirm that carbenium ions, rather than alkoxides, are reactive intermediates in catalytic alkene cracking at 773 K.
Keywords
Metadynamics, Molecular dynamics, Density functional theory, Zeolite ZSM-5, Catalysis, Alkene adsorption, INITIO MOLECULAR-DYNAMICS, TOTAL-ENERGY CALCULATIONS, AUGMENTED-WAVE METHOD, N-BUTENE CONVERSION, C-13 MAS NMR, AB-INITIO, CATALYTIC CRACKING, ZEOLITE CATALYSTS, CARBENIUM IONS, ACIDIC ZEOLITE

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Chicago
Cnudde, Pieter, Kristof De Wispelaere, Jeroen Van der Mynsbrugge, Michel Waroquier, and Veronique Van Speybroeck. 2017. “Effect of Temperature and Branching on the Nature and Stability of Alkene Cracking Intermediates in H-ZSM-5.” Journal of Catalysis 345: 53–69.
APA
Cnudde, P., De Wispelaere, K., Van der Mynsbrugge, J., Waroquier, M., & Van Speybroeck, V. (2017). Effect of temperature and branching on the nature and stability of alkene cracking intermediates in H-ZSM-5. JOURNAL OF CATALYSIS, 345, 53–69.
Vancouver
1.
Cnudde P, De Wispelaere K, Van der Mynsbrugge J, Waroquier M, Van Speybroeck V. Effect of temperature and branching on the nature and stability of alkene cracking intermediates in H-ZSM-5. JOURNAL OF CATALYSIS. 2017;345:53–69.
MLA
Cnudde, Pieter, Kristof De Wispelaere, Jeroen Van der Mynsbrugge, et al. “Effect of Temperature and Branching on the Nature and Stability of Alkene Cracking Intermediates in H-ZSM-5.” JOURNAL OF CATALYSIS 345 (2017): 53–69. Print.
@article{8509795,
  abstract     = {Catalytic cracking of alkenes takes place at elevated temperatures in the order of 773--833 K. In this work, the nature of the reactive intermediates at typical reaction conditions is studied in H-ZSM-5 using a complementary set of modeling tools. Ab initio static and molecular dynamics simulations are performed on different C4single bond C5 alkene cracking intermediates to identify the reactive species in terms of temperature. At 323 K, the prevalent intermediates are linear alkoxides, alkene \ensuremath{\pi}-complexes and tertiary carbenium ions. At a typical cracking temperature of 773 K, however, both secondary and tertiary alkoxides are unlikely to exist in the zeolite channels. Instead, more stable carbenium ion intermediates are found. Branched tertiary carbenium ions are very stable, while linear carbenium ions are predicted to be metastable at high temperature. Our findings confirm that carbenium ions, rather than alkoxides, are reactive intermediates in catalytic alkene cracking at 773 K.},
  author       = {Cnudde, Pieter and De Wispelaere, Kristof and Van der Mynsbrugge, Jeroen and Waroquier, Michel and Van Speybroeck, Veronique},
  issn         = {0021-9517},
  journal      = {JOURNAL OF CATALYSIS},
  keyword      = {Metadynamics,Molecular dynamics,Density functional theory,Zeolite ZSM-5,Catalysis,Alkene adsorption,INITIO MOLECULAR-DYNAMICS,TOTAL-ENERGY CALCULATIONS,AUGMENTED-WAVE METHOD,N-BUTENE CONVERSION,C-13 MAS NMR,AB-INITIO,CATALYTIC CRACKING,ZEOLITE CATALYSTS,CARBENIUM IONS,ACIDIC ZEOLITE},
  language     = {eng},
  pages        = {53--69},
  title        = {Effect of temperature and branching on the nature and stability of alkene cracking intermediates in H-ZSM-5},
  url          = {http://dx.doi.org/10.1016/j.jcat.2016.11.010},
  volume       = {345},
  year         = {2017},
}

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