New Approach to Enhance CO₂ Capture of "molecular Basket" Sorbent by Using 3-Aminopropyltriethoxysilane to Reshape Fumed Silica Support

Here we report a new approach to enhance CO₂ capture and separation over a solid molecular basket sorbent by reorganizing the aggregation of fumed silica (FS) support particles with the addition of 3-aminopropyltriethoxysilane (APTES). After APTES modification, although the surface area of fumed silica decreased, the total pore volume increased significantly, more than 2 times larger than that of fumed silica itself. Compared to fumed silica supported PEI sorbent, the 30PEI/APTES-FS sorbent can achieve a CO₂ capacity as high as 130.4 mg-CO₂/g-sorb, a 44% increase from 90.4 mg-CO₂/g-sorb over 30PEI/FS. The amine efficiency of PEI for CO₂ sorption was also improved by over 25%. Furthermore, both the CO₂ sorption and desorption kinetics were greatly enhanced by 1.23 and 1.61 times, respectively, compared to the PEI/FS sorbent without APTES modification. In addition, the stability and regenerability of PEI/FS sorbent was also greatly improved.