Determination of diffusion coefficient of C2H6 and CO2 in hydrocarbon solvents by molecular dynamics simulation.

• Diffusion coefficients of C 2 H 6 and CO 2 in some hydrocarbon solvents were predicted by molecular dynamics simulation. • COMPASS force field showed better predictions in comparison with other force fields (Universal, Dreiding, Cvff, and Pcff). • Effect of temperature on the diffusivities and the activation energies and pre-exponential constants were determined. In this paper, the diffusion coefficients of C 2 H 6 and CO 2 in various hydrocarbon solvents have been determined using molecular dynamics simulation at different temperatures and atmospheric pressure. Effect of force field type and number of cell molecules on MD simulation results were investigated. The optimum number of molecules in amorphous cell was obtained and it was found that COMPASS force field showed the best result in comparison with the other investigated force fields forces (Universal, Dreiding, Cvff, and Pcff). In addition, the diffusion coefficients of ethane and CO 2 were found to comply with the Stokes–Einstein equation. These coefficients were calculated from the slope of mean square displacement (MSD) curves. Temperature changes also showed an increasing effect on the diffusion coefficients and the activation energies (Ea) and pre-exponential constants (D 0) for C 2 H 6 diffusion in heptane and hexane solvents were obtained using Arrhenius theory. The simulated results indicated a good agreement with the experimental data for C 2 H 6 in heptane, hexane, octane, dodecane, and hexadecane solvents and CO 2 in hexadecane solvent. [ABSTRACT FROM AUTHOR]