Theoretical studies of energetics and diffusion of aromatic compounds in supercritical carbon dioxide

Atomic and molecular interactions of aromatic compounds in carbon dioxide a re studied with ab initio and molecular dynamics techniques. Ab initio calc ulations are used to determine the nature of the CO2-CO2, CO2-benzene, and benzene-benzene interactions. We select an explicit all-atom force field wi thout partial atomic charges to describe the intermolecular and intramolecu lar pair interactions of CO2 with benzene and toluene. Molecular dynamics s imulations are used to calculate diffusion coefficients for benzene and tol uene at infinite dilution in CO2 along isotherms at 313.15, 323.15, and 333 .15 K, in the density range from 1.35 rho(c) to 2.10 rho(c) (rho(c) = criti cal CO2 density). Diffusion coefficients are also calculated with a model b ased on perturbation theory of simple liquids. The calculated diffusion coe fficients agree fairly well with the experimental results of Suarez et al. (Chem. Eng. Sci. 1993, 48, 2419).