Molecular Dynamic Simulation of Diffusion Coefficients for Alkanols in Supercritical CO21

Abstract

The infinite dilution diffusion coefficients (D₁₂) of methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol in supercritical CO₂ (scCO₂) at 313.2 K and 10–16 MPa were simulated by molecular dynamics (MD) simulation. The microscopic structure was also analyzed by calculation of the radial distribution function, coordination number (CN) between the center mass of solute and solvent molecules, and the average number of hydrogen bonding of this system. In infinite dilute solution, the probability of forming hydrogen bond between alkanol molecules is greatly reduced relative to pure alkanol fluid, and the weak hydrogen bonds formed between alkanol and CO₂ molecules. In general, this work provides a reliable simulation method for transfer properties of solutes in scCO₂. The prediction data were provides for the design and development of chemical processing. The results are helpful for one to deeper understand the relationship between microscopic structures of fluid and its transfer properties.