DIFFERENTIAL HEATS OF TOLUENE ADSORPTION ON ZEOLITE Cu2+ZSM-5

Abstract

This article presents the results of differential heats and entropy of adsorption of toluene in CuZSM-5 zeolite. For measurements of isotherms and differential heat of adsorption, a system consisting of a universal high-vacuum adsorption unit and an attached differential modified Tian-Calve microcalorimeter DAC-1-1A was used to provide direct quantitative and qualitative characteristics of the nature and forces of adsorption interaction. The correlation between the adsorption-energy characteristics was found and the molecular mechanism of toluene adsorption in CuZSM-5 zeolite in the whole filling region was revealed. Toluene adsorbed in CuZSM-5 zeolite is located in the first coordination sphere with Cu2+ cation, forming two-dimensional complexes. It was found that the charge density significantly affects the mechanism, the energy of adsorption and the number of adsorbed molecules. This work shows how calorimetric data can be used to complement crystal structure results and detect subtle adsorbent/adsorbate interactions at the molecular level.