Spherical amine grafted silica aerogels for CO₂capture

The objective of this research was to develop a novel spherical amine grafted silica aerogel for CO2 capture. A spherical silica gel was synthesized by dropping a sodium silicate based silica sol into an oil bath. Amine grafting was achieved by bonding 3-aminopropyltriethoxysilane onto the framework of the silica gel. The spherical amine grafted silica gels were dried using vacuum drying to prepare the spherical amine grafted silica aerogels (SASAs). The synthetic mechanism of the SASAs was proposed. The structures and the CO2 adsorption performances of SASAs were researched. The amine loading of the SASAs increased with the grafting time, however, the specific surface area and pore volume sharply decreased owing to the blockage of the pore space. Excess amine loading led to the decrease of the CO2 adsorption capacity. The optimal CO2 adsorption capacity was 1.56 mmol g-1 with dry 1% CO2 and at 35 °C. This work provides a low-cost and environmentally friendly way to design a capable and regenerable adsorbent material.