Effects of the core of liquid-like SiO2 nanoparticle organic hybrid materials on CO2 capture

A series of specific liquid-like silicon dioxide (SiO2) nanoparticle organic hybrid materials (NOHMs) were successfully prepared by employing different contents of SiO2 as the core, 3-glycidoxypropyl trime thoxysilane (KH-560) or 3-(trihydroxysilyl)-1-propane sulfonic acid (SIT) as the corona and polyetheramine M-1000 (M-1000) as the canopy. These materials showed a solvent-free and liquid-like state at room temperature. The effect of the SiO2 content in the NOHMs with different bonding types on the CO2 capture capacity was investigated at 298 K and CO2 pressures ranging from 1.0 to 2.5 MPa. It was demonstrated that the capacity of the sorbents improved with the decreasing of SiO2 content. This result was due to the larger number of reactive groups and lower viscosity of the NOHMs. The reactive groups, such as secondary amine and ether groups, react with CO2 molecules, while the lower viscosity creates larger molecular gap and weaker intermolecular forces, which facilitates the penetration of CO2 molecules into the potential space between organic chains. In addition, the NOHMs synthesized via covalent bonds had a much better CO2 capture capacity than the NOHMs with ionic bonds and the same content of SiO2, owing to the protonation of the amine groups in the ionic bond-typed NOHMs, which renders them inactive for CO2 uptake.