Silica Supported MgO as An Adsorbent for Precombustion CO₂ Capture

MgO-silica nanocomposites were synthesized by dispersing MgO on three different silica supports, viz., ordered mesoporous MCM-41, SBA-15, and the nonporous fibrous silica nanospheres material (KCC-1; KAUST Catalysis Center-1) using a simple wet impregnation-calcination procedure. The materials were evaluated for intermediate-temperature CO₂ adsorption (200 °C) applicable to precombustion CO₂ capture in integrated gasification combined cycle (IGCC). The results indicate that both CO₂ adsorption capacity and kinetics are substantially improved upon dispersion of MgO on silica supports compared with single component MgO. The morphology of the silica regulates the degree of improvement in CO₂ adsorption capacity. Nanoflower silica KCC-1 supported MgO, studied for CO₂ capture for the first time, shows an approximately 1700% higher CO₂ capacity than pristine MgO and 80-110% higher than MgO supported by the other conventional ordered mesoporous silica, that is, MCM-41 or SBA-15. The outstanding adsorption performance of KCC-1 supported MgO is attributed to superior dispersion and 35-1000% higher accessible specific surface area of the bioinspired nanoflower KCC-1 composite compared with MCM-41- and SBA-15-based composites. This research paves the way for developing silica supported adsorbents with readily accessible surface for various gas separation, sensoring, and storage applications.