A. Auroux et al., Acid sites investigation of simple and mixed oxides by TPD and microcalorimetric techniques, THERMOC ACT, 379(1-2), 2001, pp. 227-231
The present work deals with the acid properties of silica, alumina and two
mixed oxides obtained by grafting silica on alumina (SA sample) or alumina
on silica (AS sample). The. surface acidity of the samples, of both Lewis a
nd Bronsted type, was determined by means of microcalorimetry and temperatu
re programmed desorption (TPD), using pyridine and 2,6-dimethylpyridine as
probe molecules. Both techniques point out that the grafted mixed oxides SA
and AS have acidic properties different from those of the pure alumina and
silica starting supports. Some differences exist, in terms of acid sites s
trength distribution, between TPD and calorimetric results, which can be re
asonably attributed to the different activating conditions of the samples.
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