DETERMINATION OF ACID SITES IN SOLID CATALYSTS BY MASS-SPECTROMETRY

This paper reports a temperature-programmed desorption mass spectromet ry method for determining the nature, number and distribution, accordi ng to relative strength, of acid sites in solid catalysts. By using py ridine as the titrant, the overall, Bronsted (B) and Lewis (L) aciditi es are determined. The Bronsted acidity is obtained individually by ti tration with 2,6-dimethylpyridine, whereas the Lewis acidity is calcul ated by difference. The desorption temperatures for the amines are use d 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)).