The surface acidity of a series of commercial Slid Chemie acid-treated montmorillonite clays (K-catalysts) has been evaluated by a wide range of complementary experimental techniques. The different methods applied allow a rather complete characterisation of the surface acidity providing a complete picture of the Lewis/Bronsted acid strength/density of the surface sites. IR data show that the Bronsted sites on these catalysts are relatively weak and provide evidence for a slight increase of the strength and the density of Bronsted sites in the order K5 < K10 <similar to> K20 < K30 in full agreement with the trend in iso-butene conversion, which is a measure of the strength and/or the abundancy of Bronsted sites. The apparent contradiction of these data with those obtained from the ammonia adsorption and iso-propanol conversion experiments can be explained by the structural and chemical modification of the clays upon acid treatment. (C) 2001 Elsevier Science B.V. All rights reserved.
A study of the surface acidity of acid-treated montmorillonite clay catalysts
Trombetta M;
2001-01-01
Abstract
The surface acidity of a series of commercial Slid Chemie acid-treated montmorillonite clays (K-catalysts) has been evaluated by a wide range of complementary experimental techniques. The different methods applied allow a rather complete characterisation of the surface acidity providing a complete picture of the Lewis/Bronsted acid strength/density of the surface sites. IR data show that the Bronsted sites on these catalysts are relatively weak and provide evidence for a slight increase of the strength and the density of Bronsted sites in the order K5 < K10I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
