Continuous generation of mesoporous silica particles via the use of sodium metasilicate precursor and their potential for CO2 capture

Fast synthesis of spherical mesoporous silica materials using the inorganic silica source of sodium metasilicate (Na2SiO3·9H2O) via aerosol spray of evaporation induced self-assembly method is presented in this study. The XRD, TEM and N2 adsorption–desorption measurements indicated the presence of a well ordered hexagonal array with uniform mesostructures. The mesoporous silica spherical particles (MSPs) obtained via sodium metasilicate precursor, denoted as MSP(NaSi), possessed high specific surface areas (820–1060 m2/g), narrow pore size distributions (2.4–2.8 nm) and large pore volumes (0.60–0.88 cm3/g). Their particle sizes were smaller while the particle size distributions were narrower than the MSP made from the organic silica precursor of TEOS, denoted as MSP(TEOS). The MSPs were further applied as adsorbents for the capture of CO2 greenhouse gas. It was demonstrated that the amine functionalized MSP(NaSi) adsorbent, TEPA/MSP(NaSi)-18, exhibited an adsorption capacity (67 mg CO2/g adsorbent) of only slightly less than that of MSP(TEOS) (83 mg CO2/g adsorbent), and its capacity is much higher than that of TEPA functionalized ZSM-5 zeolite (12 mg CO2/g adsorbent). The results suggested that MSPs synthesized using low-cost Na2SiO3 via aerosol route can be a cost-effective mesoporous adsorbent for CO2 capture.