Diffusion coefficients for binary alkane mixtures to 573 K and 3.5 MPa

An automated Taylor dispersion apparatus, designed to operate from 298 to 573 K and 101 to 3,450 kPa (14.7 to 500 psia), was used to measure diffusion coefficients at infinite dilution for the solutes n‐octane, n‐decane, n‐dodecane, n‐tetradecane, and n‐hexadecane in the solvents n‐heptane and n‐dodecane. Dodecane viscosity and density also were measured at all conditions. Various predictive theories are tested in light of the new data, and a correlation based on the data at high temperature and pressure is presented. The data are well represented by a free‐volume expression of the form {article}{empty}{document}DAB /√ T = β \,(V - VD){document} . The data given here extend the available data base for alkane/alkane diffusion by 100 to 200 K, and allow evaluation of predictive theory over an extended range of temperatures.