CRCU

Chemical Research in Chinese Universities ›› 1992, Vol. 8 ›› Issue (4): 337-342.

• Articles •     Next Articles

A Study of Acidic Sites in H[M]-ZSM-5 Zeolites by XPS, IR and TPD

XTAO Feng-shou1, XU Ru-ren1, XU Yi-hua1, WEI Quan2   

  1. 1. Department of Chemistry, Jilin University, Changchun, 130023;
    2. Center of Measurement and Analysis, Jilin University, Changchun, 130023
  • Received:1991-08-05 Online:1992-12-24 Published:2011-08-17

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Abstract: The present paper covers an X-ray photoelectron spectroscopic (XPS) method proposed for identifying Bronsted and Lewis acidic sites in zeolites and estimating acidic strength of these sites. It was found that the adsorption of pyridine on different acidic sites of H[M]-ZSM-5 zeolites exhibited three peaks: A(402.20-401.30 eV), B(400.95-400.40 eV) and C(399. 40-399. 10 eV). The peaks Aand Bare assigned to the N1xlevel of pyridine adsorbed on Bronsted and Lewis acidic sites, and peak Cis assigned to the N1xlevel of pyridine adsorbed on a weak Lewis site and/or strongly physisorbed pyridine, respectively. The comparison of the ratio of the Bronsted and Lewis acidic sites determined from the relative intensities of the N1x, peaks with IRspectroscopic data shows that there is an inhomoge-neous distribution of Bronsted and Lewis acidic sites in H[M]-ZSM-5 zeolites.

Key words: Acidity, XPS,H[M]-ZSM-5 zeolites, Adsorption of pyridine, IR and TPD