Influence of temperature and high-pressure on the adsorption behavior of scCO2 on MCM-41 and SBA-15

Actually there is a growing interest in various so-called adsorption precipitation processes. Thereby, an organic molecule is dissolved in supercritical CO2, followed by the adsorption of the molecule onto a substrate (e.g. MCM-41, SBA-15) and subsequent solute precipitation due to pressure decrease. For the design of such processes it is essential to understand the complex nature of the multicomponent adsorption behavior. Thus as a first step, there is a need for studying the adsorption behavior of the particular CO2-substrate system at the respective process conditions. Due to a lack of experimental data adsorption isotherms of CO2 on MCM-41 and SBA-15 were measured at temperatures from T = 298 to 353 K and pressures up to p = 25 MPa. Based on these results, the absolute amount adsorbed was calculated from the surface excess amount. Finally, the isosteric heat of adsorption for CO2 was calculated by using the Clausius - Clapeyron equation.