Adsorption behavior of BTX in Supercritical Carbon Dioxide on Molecular
Sieving Carbon Using Chromatography and Numerical Simulation Method
Separation method using chromatograph measurements were made for the adsorption of benzene, toluene and xylene (BTX) on binary porous structure possessing molecular sieving carbon (MSC) in supercritical fluid CO2 mixed with organics. Moment analysis considering function of micropore, macropore, axial dispersion and external mass transfer was applied to the response peak with experimental technique, and examined dependences of adsorption equilibrium constants, K*, and micropore diffusivity, D, on the amount adsorbed. Then, to use Markham-Benton equation for obtaining the saturation adsorption amount and equilibrium constant (BTX and CO2), the adsorption isotherms was carried out the curve fitting method of least squares by the solver.
Stop & Go method was used as one of the simulation methods of chromatography which examine adsorption equilibrium and rate. Experimental adsorption equilibria and adsorption rate parameters for organics and CO2 were made use of Stop & Go simulation. Fig.1 shows basic concept of this simulation thought completely-mixed-layer bank of N in axial direction of column. If the flow stopped only dt second, the adsorbate was made batch adsorption into each cells. After dt second, think material balance in absorption and desorption of each cell within a stopped time frame.
In this study, chromatographic measurements were made for the adsorption of BTX on MSC in supercritical fluid CO2. Supercritical fluids chromatograph (SFC) packed with MSC was used to detect pulse responses of organics. Adsorption equilibria and adsorption dynamics for organics and CO2 were obtained by moment analysis of the response peaks and Stop & Go simulation.

Fig. 1 Stop & Go method basic concept