Diffusion of Liquid Hydrocarbons in Supercritical CO2 by Photon Correlation Spectroscopy

Binary diffusion coefficients of benzene and heptane in supercritical CO2 were measured by photon correlation spectroscopy. The measurements were carried out along isochores in the dense gas region at concentrations less than 5 mole percent hydrocarbon. The results of an analysis of data using mode‐mode‐coupling theory indicated that the exponent of the correlation length, ν = 0.67 ± 0.03 on the critical isochore. On the other hand, ν = 0.86 ± 0.05 was obtained on isochores that were not critical and the background contribution became significant.