Diffusion behavior of the model diesel components in different polymer membranes by molecular dynamic simulation

Abstract

Molecular dynamic (MD) simulation was used to investigate the diffusion behavior of the model diesel components (dibenzothiophene (DBT) and methylnaphthalene (MNA)) in four different membranes of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polymethyl acrylate (PMA), and polymethyl methacrylate (PMMA). The simulation results of PVA were quite consistent with the experimental results, which indicated that the dynamic simulation method might be able to roughly predict the diffusion behavior of the model diesel components in polymer membranes. The diffusion coefficients of DBT and MNA in four different membranes were calculated, and it was obviously discovered that the PVC membrane was the only material improving the diffusion selectivity of DBT over MNA in this study, which demonstrated that the PVC membrane might be beneficial to diesel fuel desulfurization. The micro diffusion mechanism of DBT and MNA inside polymer membrane was investigated by analyzing the interaction energy between diffusion molecule and polymer membrane, fractional free volume of polymer membrane, and the mobility of polymer chains. And it was concluded that interaction energy was the key factor for all the polymer systems.