Adsorption characteristics of toluene and naphthalene on silica gel under the subcritical and supercritical conditions using chromatographic techniques

Chromatographic techniques were used for measuring the adsorption of toluene and naphthalene on silica gel packed beds under the supercritical and subcritical conditions at 301-318 K, 54-150 atm, and 0.3<N_Re<7. The moment method was used to determine the equilibrium constants and rate parameters. The results showed a significant reduction of the adsorption equilibrium constant as the pressure changed from subcritical to supercritical; the axial dispersion coefficients at supercritical conditions were intermediate to those of what would be obtained in gases and liquids; in the pressure range where density fluctuations with concentration were large, axial dispersion was influenced by both natural convection and molecular diffusion; diffusion within the pores of the adsorbent was found to be the major resistance to adsorption. In addition to these parameters, partial molar volumes were determined from the chromatographic experiment and were found to agree well with the values reported in earlier work.