Surface grafting of silica nanoparticles using 3-aminopropyl (triethoxysilane) to improve the CO2 absorption and enhance the gas consumption during the CO2 hydrate formation

In this study, the surface of silica nanoparticles is modified using an organosilane (APTES: 3-aminopropyl (Triethoxysilane)). The surface-grafted nanosilica is employed as an additive to increase the CO2 storage capacity of gas hydrate. The hydrate formation experiments are performed to measure the amounts of stored gas in the hydrate phase in the presence of various aqueous mixtures, that is, APTES, silica, and the surface-grafted nanosilica. The experiments are implemented for APTES with volume concentrations of 0.3 and 0.5%, grafted nanosilica with mass concentrations of 0.05, 0.1, 0.15, 0.2, and 0.25%, and the nanosilica with mass fraction of 0.2%. The amounts of CO2 consumption, water to hydrate conversions, storage capacities, and apparent rate constants are obtained for all of the experiments. The results are compared with the formation of gas hydrate in the presence of pure water. The results indicate that the two concentrations of APTES have a slight positive effect (around 10% improvement) on the amount of CO2 consumption during the hydrate formation compared to the pure water. The surface-grafted nanosilica leads to more CO2 consumption compared to the APTES and nanosilica for all concentrations. The maximum amount of stored CO2 and CO2 storage capacity are achieved by using surface-grafted nanosilica with a mass fraction of 0.2%. The surface-grafted nanosilica improves the CO2 storage about 42.6% in comparison with the pure water and 35% compared to the silica nanoparticles. Improvement of heat transfer, mass transfer, and CO2 absorption into the modified silica nanofluid results in an enhancement in the CO2 storage compared to the other mixtures. (c) 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.