Modeling carbon dioxide adsorption on polyethylenimine-functionalized TUD-1 mesoporous silica

Samples of porous, foam-like TUD (Technische Universität Delft)-1 mesoporous silica were functionalizedwith polyethylenimine and were used as a substrate for CO2 adsorption. Produced solids were characterizedby means of electron microscopy, thermogravimetric analysis, and N2 adsorption/desorption at 77 K,in order to prove that polymer chains efficiently filled the pores of functionalized samples. CO2 adsorptionisotherms on polyethylenimine-containing TUD-1 were evaluated at T = 298, 313, 328, and 348 K forpressures up to 100 kPa by means of a volumetric technique. The CO2 adsorption capacity proved to besignificantly dependent on temperature, with the highest capacity encountered at T = 348 K. Theexperimental data for CO2 adsorption were satisfactorily described by means of the Langmuir isotherm,and the dependence of the isosteric heat on the fractional coverage of the adsorbent was evaluated bymeans of the van’t Hoff equation, showing values in the order of 80 kJ/mol for a fractional coverage ofabout 50%.