Development of high-temperature CO2 sorbents made of CaO-based mesoporous silica

This study develops a modified CaO-based mesoporous CO2 sorbent with high sorption capacity (about 10 mol/kg sorbent) and long-term durability. Highly ordered mesoporous SBA-15 molecular sieves used as carriers were successfully synthesized through direct-synthesis by using non-ionic surfactants as the structure-directing agent under strong acidic conditions. Calcium ions using calcium acetate as the precursor were finely dispersed onto prepared carriers using an impregnation method. Calcium oxide was obtained under calcination at high temperature. Analytical techniques, such as X-ray diffraction patterns, nitrogen physisorption isotherms, scanning electron microscopy/energy dispersive spectrometer, and transmission electron microscopy, were used to characterize the synthesized mesoporous materials. The thermo-gravimetric analysis was used to test the performance of CO2 capture using prepared CaO-modified sorbents. The property and carbon dioxide sorption ability of the substrates and sorbents were examined and discussed. Carbon dioxide was effectively adsorbed, concentrated, and separated using the reasonable reaction paths. Durability tests showed that the CO2 adsorption ratio remains at 80% after 40 cyclic runs under a carbonation temperature at 700 °C and calcination temperature at 910 °C, respectively. The results showed that the structural stability of the sorbents was improved sufficiently under high temperature and cyclic sorption–desorption operations.