Abstract: The adsorption thermodynamics (adsorption heat, enthalpy change, entropy change) and the related regularities of n-octane adsorbed on REY zeolites with different content of rare earth ion was studied by high precision intelligent gravimetric analyzer (IGA) and temperature programmed desorption (TPD) techniques. The activity modification principle was analyzed by TPD combined with dynamic results. It is discovered that the interaction magnitude of the adsorbent with the adsorption sites on the zeolite is related to the content of the rare earth. A higher content of rare earth introduction strengthens interaction and make the adsorbent stay in zeolite long time, leading to an excessive cracking and coking due to strong adsorption and difficult desorption. The introduction of appropriate amount of rare earth (4% Ce2O3) can mildly modulate the adsorption strength on zeolite active sites, so that the order is regularized and the residence time of adsorbate molecule in the zeolite pores is changed, which is helpful macromolecule cracking reaction occur and improve the yield of the target product.

Key words: rare earth content, adsorption thermodynamics, interaction, activity, catalytic activity