Calorimetric study on the state of benzene and cyclopentane sorbed on H-ZSM-5 with different Si/Al ratios

Differential molar heats of sorption have been determined calorimetrically for benzene and cyclopentane on H-ZSM-5-type zeolites with different aluminium contents. The results show that the structural OH-groups represent energetically preferred sorption sites for benzene and presumably also for cyclopentane. The occurrence of inflection points in the sorption isotherms as well as of pronounced maxima in the heat of sorption curves of benzene and cyclopentane on the Al-poor H-ZSM-5 samples indicates that the influence of sorbate-sorbate interactions on the state of the sorbed molecules rises with decreasing Al content.