(719t) Adsorption of Btx on MSC5A in Supercritical CO2,Molecular Simulation

Supercritical CO2 fluid is attractive solvent whose solubility of organics can be changed with changes of pressure and temperature. New process of adsorptive separation using supercritical fluid might be possible since removal of adsorbate from adsorbent can be performed efficiently. Molecular simulation is now attracting much attention as a powerful means of understanding and estimating adsorption phenomena, i.e., adsorption equilibria and adsorption dynamics in microporous adsorbents. In this study, chromatographic measurements were made for the adsorption of benzene, toluene and m-xylene on molecular sieving carbon (MSC) in supercritical fluid CO2. Supercritical chromatograph packed with MSC was used to detect pulse responses of organics. Adsorption equilibria and adsorption dynamics for organics were obtained by moment analysis of the response peaks. Dependences of adsorption equilibrium constants, K*, and micropore diffusivity, D, on the amount adsorbed were examined.And, molecular simulation of multicomponent adsorption equilibria was performed, and potential parameters were determined in comparing the simulation with experimental results. Simulation soft ware is Cerius2 (Version4.2) made by MSI. The purpose of performing simulation is to elucidate an adsorption mechanism on the molecule level. The dependencies of adsorption equilibrium constants, K*, and micropore diffusivity, D, of toluene, benzene and m-xylene, on molarity of toluene with each parameters of temperature or pressure were obtained. It was found that the values of K* and D for an organic substance depended on the amount adsorbed of other organics strongly.