Effect of solvents coexistence on the intracrystalline diffusivity of toluene and phenol within Y-type zeolite in the liquid phase

The intracrystalline diffusivities of phenol and toluene within H–Y-type zeolite (Si/Al = 2.8) in the mesitylene, cyclohexane and 2-propanol in the temperature range from 313 to 353 K were measured using the constant volumetric method. The activation energy for the intracrystalline diffusivity of toluene within H–Y in the liquid phase was larger than that in the gas phase, indicating that the solvent coexisting within the H–Y pores affected the diffusion mechanism of toluene. The intracrystalline diffusivity of phenol within H–Y in mesitylene was smaller than that of toluene. Moreover, the intracrystalline diffusivity of phenol within dealuminated H–Y was higher than those within H–Y, which further indicated that the phenol molecule was more strongly adsorbed on the Brønsted acid sites of H–Y, and this affected the residence time of phenol on the acid sites leading to a decrease in the diffusivity. The intracrystalline diffusivities of phenol within H–Y for the three solvents were in the following order: 2-propanol > cyclohexane > mesitylene. The amount of adsorbed phenol on H–Y in 2-propanol was smallest relative to the amounts of phenol adsorbed on H–Y in the other solvents. The results indicated that the adsorption of phenol on H–Y in the different solvents affected the intracrystalline diffusivity of phenol and its activation energy.