Nature of spilt-over hydrogen on acid sites in zeolites: Observation of the behavior of adsorbed pyridine on zeolite catalysts by means of FTIR

Ryo Ueda, Toshiaki Kusakari, Keiichi Tomishige, Kaoru Fujimoto

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Spilt-over hydrogen is known to have a strong effect on the catalytic reaction on sold acid catalysts. Under a hydrogen atmosphere, the catalyst prepared by the physical mixture of Pt/SiO2 and H-ZSM-5 was very effective for the hydroisomerization or the hydrocracking of n-pentane, n-hexane, and other paraffinic hydrocarbons under a hydrogen atmosphere. FTIR and TPD were used to study the influence of spilt-over hydrogen on catalysts that were prepared by physically mixing zeolites or alumina with SiO2-supported noble metals on chemisorbed pyridine. Pyridine adsorbed on a Lewis acid site migrated to a Broensted acid site under a hydrogen atmosphere. This signified that spilt-over hydrogen should increase the desorption on the Lewis acid site, and that the possible state of spilt-over hydrogen on the Lewis acid site should be hydride, which has strong Lewis basicity. H-D exchange (-OH + D2) of the Broensted acid site was also conducted, which resulted in a complete description of interactions between spilt-over hydrogen and acid sites of zeolite.

Original languageEnglish
Pages (from-to)14-22
Number of pages9
JournalJournal of Catalysis
Volume194
Issue number1
DOIs
Publication statusPublished - 2000 Aug 15
Externally publishedYes

Keywords

  • Bronsted and Lewis acid sites
  • Hybrid catalyst
  • Hydrogen spillover
  • Proton and hydride
  • Pyridine migration
  • Zeolite

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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