The effects of high-pressure on the chemisorption process of CO2 on lithium oxosilicate (Li8SiO6)

• CO2 capture was evaluated on Li8SiO6 at high-pressure.
• CO2 is trapped chemical and physically on Li8SiO6.
• High-pressure enhances the CO2 capture between 30 and 350 °C.

High-pressure CO2 capture was evaluated on Li8SiO6. Several different high-pressure experiments were performed using CO2, and the sample products were analyzed using XRD, N2 adsorption, SEM and DSC. The results clearly showed that CO2 is chemically and physically trapped and that the CO2 chemisorption improved as a function of temperature. Depending on the temperature, Li8SiO6 reacted with 2 mol or less of CO2 to produce an external shell composed of Li4SiO4, Li2CO3 and Li2O in a non-stoichiometric reaction. Independently of the external shell composition, the final surface area and pore volume increased independent of the external shell composition and favored the second sorption process: CO2 adsorption. Therefore, high pressures enhance CO2 capture between 30 and 350 °C, promoting the chemisorption and adsorption processes.