Investigation of Mg modified mesoporous silicas and their CO 2 adsorption capacities

Abstract

CO 2 adsorption properties on Mg modified silica mesoporous materials were investigated. By using the methods of co-condensation, dispersion and ion-exchange, Mg 2+ was introduced into SBA-15 and MCM-41, and transformed into MgO in the calcination process. The basic MgO can provide active sites to enhance the acidic CO 2 adsorption capacity. To improve the amount and the dispersion state of the loading MgO, the optimized modification conditions were also investigated. The XRD and TEM characteristic results, as well as the CO 2 adsorption performance showed that the CO 2 adsorption capacity not only depended on the pore structures of MCM-41 and SBA-15, but also on the improvement of the dispersion state of MgO by modification. Among various Mg modified silica mesoporous materials, the CO 2 adsorption capacity increased from 0.42 mmol g −1 of pure silica SBA-15 to 1.35 mmol g −1 of Mg–Al–SBA-15-I1 by the ion-exchange method enhanced with Al 3+ synergism. Moreover, it also increased from 0.67 mmol g −1 of pure silica MCM-41 to 1.32 mmol g −1 of Mg–EDA–MCM-41-D10 by the dispersion method enhanced with the incorporation of ethane diamine. The stability test by 10 CO 2 adsorption/desorption cycles showed Mg–urea–MCM-41-D10 possessed quite good recyclability.