Adsorption kinetics of rhodium (III) acetylacetonate onto mesoporous silica adsorbents in the presence of supercritical carbon dioxide

摘要

The adsorption kinetics of rhodium (III) acetylacetonate (Rh(acac)(3)) onto three types of mesoporous silica adsorbents, MCM-41, HMS, and MSU-H, in the presence of supercritical carbon dioxide (scCO(2)) at temperatures from 313 to 353 K and at a pressure of 15.0 MPa were studied using fixed-bed adsorption measurements. The breakthrough curves obtained with the measurements were correlated by a mathematical kinetic model using only one fitting parameter, the effective diffusion coefficient of Rh(acac)(3) in pores (D-e). The determined D-e values depended strongly on the temperature and the types of mesoporous silica used, which could be described using a generalized model that includes the parameters in consideration of the pore structure of the adsorbents (porosity and tortuosity) and the diffusion coefficient of Rh(acac)(3) in the bulk scCO(2) phase.