DETERMINATION OF ACID SITES IN SOLID CATALYSTS BY MASS-SPECTROMETRY

This paper reports a temperature-programmed desorption mass spectrometry method for determining the nature, number and distribution, according to relative strength, of acid sites in solid catalysts. By using pyridine as the titrant, the overall, Bronsted (B) and Lewis (L) acidities are determined. The Bronsted acidity is obtained individually by titration with 2,6-dimethylpyridine, whereas the Lewis acidity is calculated by difference. The desorption temperatures for the amines are used as measures of the relative strengths of the different types of acid sites. The results obtained are compared with those provided by a UV-visible spectrophotometric method reported elsewhere (J. M. Campelo et al., Can. J. Chem. Vol. 61, p. 544 (1983)).