Role of adsorption in zeolite-catalyzed hydrocarbon cracking reaction

The activity for hydrocarbon cracking of zeolite catalysts depends on the type of zeolite and steam treatment. By comparing the activities of different zeolites under the condition where the catalyst did not undergo deactivation and the product distributions were identical, and presumably for the monomolecular mechanism, it was found that there were no differences in the chemical properties of the active sites in the zeolites. The apparent differences in catalytic activities among zeolites could be attributed to different concentrations of adsorbed alkane reactants, which is a consequence of the different strength of interaction of the alkyl groups with the zeolite walls. The latter may also be a significant contribute to the observed different strengths of interaction of alkyl amines with the Brønsted acid sites in zeolites.