Acta Phys. -Chim. Sin. ›› 1985, Vol. 1 ›› Issue (06): 533-542.doi: 10.3866/PKU.WHXB19850606

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AN INFRARED SPECTROSCOPY METHOD FOR MEASURING THE BRÖNSTED ACID OF ZSM-5 AND THE STUDY OF SURFACE ACIDITY OF MODIFIED ZSM-5 ZEOLITES

Liu Xingyun; She Liqin; Li Xuanwen   

  1. Department of Chemistry, Peking University
  • Received:1984-10-17 Revised:1985-06-22 Published:1985-12-15

Abstract: Based on the studies of IR Spectra of various ZSM-5 zeolites it was found that there are two strong bands at ca. 1875 and 2000 cm~(-1) and their absorbance ratio is a characteristic value. A method to treat the data of IR spectra by using relative absorbance with 2000 cm~(-1) band as a “internal standard” has been develo- ped. The acidity of various ZSM-5 samples has been determined by this method and related to their concentrations of Brönsted acid measured by potential titration and activity of cumeue cracking. Good relationships have been found. The assignment of 1875 cm~(-1) and 2000 cm~(-1) bands has been discussed according to the experimental results. The theoretical base of this quantitive method for treating the IR spectra of ZSM-5 zeolite has been found by inferring the relation between relative absorbance and the concentration by the Beer-Lambert law.