Effect of pore size and acidity on the coke formation during ethylbenzene conversion on zeolite catalysts

Jun Huang, Yijiao Jiang, V. R Reddy Marthala, Arne Bressel, Joerg Frey, Michael Hunger*

*Corresponding author for this work

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

The present work provides solid-state 13C NMR spectroscopic evidence that the zeolites acidity and the pore size strongly affect the catalytic behavior of ethylbenzene disproportionation and coke formation. The medium-pore zeolite H-ZSM-5 (ca. 0.56 nm) and the large-pore zeolite H-Y (ca. 0.74 nm) used in this study have exclusively Brønsted acid sites, but with different acid strength. Due to the transition state shape selectivity of ethylbenzene disproportionation, ethylbenzene transalkylation on H-Y takes place at low reaction temperature without side-reactions. On H-ZSM-5, dealkylation/realkylation was observed and generation of alkylcarbenium ions resulted in secondary reactions. These alkylcarbenium ions initiate coke formation on zeolite H-ZSM-5 via oligomerization, six-ring closure, and aromatization of alicyclic hydrocarbons. Ethylbenzene disproportionation on large-pore zeolites Y is an attractive reaction due to its low reaction temperature, high selectivity without side-reactions, and low coke formation. Medium-pore zeolite H-ZSM-5 showed higher reactivity for dealkylation of ethylbenzene and protolytic cracking of light alkanes due to its narrow channels and stronger Brønsted acid sites.

Original languageEnglish
Pages (from-to)277-283
Number of pages7
JournalJournal of Catalysis
Volume263
Issue number2
DOIs
Publication statusPublished - 25 Apr 2009
Externally publishedYes

Keywords

  • Acidic zeolites
  • Coke formation
  • Ethylbenzene disproportionation
  • In situ solid-state NMR spectroscopy
  • Pore size
  • Transition state shape selectivity

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