Amine-grafted mesoporous copper silicates as recyclable solid amine sorbents for post-combustion CO₂ capture

Highlights: • A novel amine-grafted mesoporous coppersilicate named CSNS-TA was synthesized for CO₂ capture. • The CO₂ adsorption was at relatively mild conditions, e.g., ambient temperature and pressure. • CSNS-TA presents high CO₂ capture capacity, recyclability and long-term stability. • The high efficiency was proposed from the unique microstructure, stable amines grafted on CSNS. - Abstract: Amine-functionalized nanomaterials have significant potential in CO₂ capture technology because of their low energy consumption, stable performance, and high regeneration capacity. Novel amine-functionalized adsorbents composed of copper silicate nanospheres (CSNSs) grafted with mono-, di- and tri-aminosilanes were synthesized for CO₂ capture. The synthetic process and formation mechanism were systematically investigated using transmission electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, and N₂ physisorption analysis, etc. The copper silicates with rich surface hydroxyl groups, significant surface areas and mesoporous structures facilitated chemical modification of amines, leading to a high CO₂ adsorption capacity (a maximum CO₂ uptake of 47.88 mg/g) and excellent cyclic regenerability (maximum deviation of 3.51% after 20-times test) for CSNS-TA. In addition, the CO₂ capture process was carried out under relatively mild conditions, e.g., adsorption at 298 K, desorption at 373 K and ambient pressure, suggesting that these amine-modified CSNSs have potential as solid sorbents for CO₂ capture.