Cracking catalysts base exchanging properties

Acidity is the main property required of a zeolite catalyst, especially when used in a cracking process. Decationation, attained, as previously mentioned (Sect. 6.2) via cation-exchange with NH and successive deammoniation, increases the concentration of acid sites. Since only the strong acidic sites are catalytically effective, it is of extreme interest to obtain information on the abundance and distribution of such sites. This may be done by several techniques, such as IR spectroscopy [63] or calorimetry [64], but also thermal procedures may be applied. In this case the preactivated zeolite catalyst is allowed to absorb a weak base, such as an amine or more often ammonia, and then is subjected to thermal analysis (TPD, DSC), in order to record the thermal profile of the desorption. 

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