Study On Mass Transfer Behavior Of Gasoline Components In Polymer Membrane

The application of gasoline desulphurization by pervaporation membrane in the petrochemical industry has not only widened the research field of membrane technology, but also provided a new and effective gasoline desulphurization technology. The aim of this paper is to study the solution and diffusion behavior of small-molecule solvent in polymer membrane based on the solution-diffusion model.The adsorption coefficient and diffusion coefficient of pure component for five component simulated gasoline in PEG membrane can be regressed from sorption experiment. It is precisely because the difference between adsorption coefficient and diffusion coefficient provides a theoretical basis for the gasoline desulphurization by PEG membrane. Through analayzing the swelling experiment results of the two component simulated gasoline in PEG membrane we can see, the total degree of swelling increases with the increasing surful content of raw material and the solubility separation coefficient keeps steady or a little lower after decreasing with the surful content of raw material.The solution behavior research between the pure component for five component simulated gasoline and the two component simulated gasoline in PEG membrane by UNIFAC, UNIFAV-FV, UNIFAC-ZM and Entropic-FV model indicates that the predictive results consistent with the experimental results. The results show that improved UNIFAC model is a high feasible research method to predict the solubility of small-molecule solvents in membrane.The Vrentas-Duda model is used to predict the diffusion coefficient, and compare with experimental values. The compared results show that the diffusion coefficient through the Vrentas-Duda model is in good agreement with the diffusion coefficient obtained by swelling experiments, the error is generally 20~60%. The results indicate that the Vrentas-Duda model is a reliable method in predicting the solvent diffusion coefficient in the polymer membrane. Furthermore, Vrentas-Duda model is used to predict the relationship of diffusion coefficient changed with the temperature and the concentration for the pure component of five component simulated gasoline in PEG membrane. Molecular simulation is used to calculate the diffusion coefficient of thiophene and n-heptane in PEG membrane.