Adsorption of benzene from benzene/n-C6 and n-C7 mixture by nano Beta zeolite with different Si/Al ratios

Abstract

The adsorption of benzene from benzene/n-alkane mixtures was studied by two types of nano Beta zeolite with Si/Al ratios of 11.5 and 24.5. Benzene was adsorbed into benzene/n-hexane and n-heptane mixtures which had 0.5% up to 10%mole fraction of benzene using batch technique in the ambient temperature. The nano Beta zeolite has active sites on its surface, which have interaction with π electron in benzene, and this can increase the heat of adsorption. The Si/Al ratio defines the number of active sites in the zeolite surface and the heat of adsorption. However, an increase in the active sites of Beta zeolite declines the entropy of adsorption. Therefore, free energy of mixing specifies the potential of adsorption in Beta zeolite.As the results indicated in all mixtures, benzene is adsorbed more than n-hexane and n-heptane into the Beta zeolite surface, which suggests that this type of zeolite has a high separation factor (∼50) for benzene in Beta zeolite (Si/Al=24.5). Also, Beta zeolite with Si/Al=24.5 had a greater separation factor than Beta zeolite with Si/Al=11.5 in similar mixtures.