Ultraviolet Raman spectroscopy characterization of coke formation in zeolites

Can Li*, Peter Stair

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

139 Scopus citations

Abstract

Ultraviolet (UV) Raman spectroscopy has been used to characterize coke formation in ZSM-5 and USY zeolites under propene at temperatures from 300K to 773K. The strong fluorescence background always present with normal Raman spectra is completely avoided in UV Raman spectra. Three groups of UV Raman bands near ~ 1390, ~ 1600 and ~ 3000 cm-1 regions were detected for the two zeolites, and these bands varied significantly at different stages of coke formation. At room temperature, adsorbed propene was formed in the two zeolites and showed similar spectra. At elevated temperatures, the coke formation behavior in the two zeolites is quite different. For example, at 773K the coke species in ZSM-5 are mainly polyolefinic and aromatic species, but poly aromatic and pregraphite species are predominant in USY. The major portion of coke species formed in ZSM-5 can be removed even by He purging at 773K while the coke species in USY are very stable and can only be removed in O2 flow at temperatures above 773K. The difference in coke formation in ZSM-5 and USY is likely due to the different pore structure and acidity of the two zeolites.

Original languageEnglish (US)
Pages (from-to)353-360
Number of pages8
JournalCatalysis Today
Volume33
Issue number1-3
DOIs
StatePublished - Jan 17 1997

Keywords

  • Carbonaceous
  • Coke formation
  • Deactivation
  • Resonance raman
  • USY
  • UV raman spectroscopy
  • ZSM-5
  • Zeolites

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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