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Catalysis Letters

, Volume 28, Issue 2–4, pp 211–222 | Cite as

A quantum-chemical study of adsorbed nonclassical carbonium ions as active intermediates in catalytic transformations of paraffins. II. Protolytic dehydrogenation and hydrogen-deuterium hetero-isotope exchange of paraffins on high-silica zeolites

  • V. B. Kazansky
  • M. V. Frash
  • R. A. van Santen
Article

Abstract

HF-21G quantum-chemical analysis of the protolytic attack of acid protons in zeolites at the C-H bonds in methane and ethane indicated that the resulting transition states depend on the sign of the bond polarization. If a hydride ion is split off from the paraffin, then the transition state resembles the adsorbed carbonium ion and the reaction results in molecular hydrogen and in formation of the surface alkoxy group. The case, when a proton tends to split off from the paraffin, corresponds to the hetero-isotope exchange of paraffins with surface OH groups. This is a concerted acid-base reaction with a transition state different from adsorbed carbonium ion.

Keywords

quantum-chemical calculations protolytic dehydrogenation zeolites paraffins 

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Copyright information

© J.C. Baltzer AG, Science Publishers 1994

Authors and Affiliations

  • V. B. Kazansky
    • 1
  • M. V. Frash
    • 1
  • R. A. van Santen
    • 2
  1. 1.Zelinsky Institute of Organic ChemistryRussian Academy of SciencesMoscowRussia
  2. 2.Schuit Institute of CatalysisEindhoven University of TechnologyMB EindhovenThe Netherlands

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