High CO2 Capture in Sodium Metasilicate (Na2SiO3) at Low Temperatures (30-60 °C) through the CO2-H2O Chemisorption Process

Na2SiO3 was synthesized by two different routes: solid-state reaction and combustion method. It was determined that Na2SiO3 sample prepared by the combustion method presented a surface area 3 times larger than the solid-state reaction sample. Different water vapor sorption experiments were performed using N-2 or CO2 as carrier gases. If N-2 was used as carrier gas, it was evidenced that Na2SiO3 is able to trap water in two different ways: physically and chemically producing Na-OH and Si-OH species. Moreover, when CO2 was used, Na2SiO3 continued trapping water, as in the previous case, but in this case CO2 was trapped, forming Na2CO3 and NaHCO3 phases. Additionally, as it could be expected, the surface area resulted to be a very important factor controlling the CO2 capture efficiency. The Na2SiO3 sample prepared by the combustion method captured up to 8.5 mmol of CO2 per gram of ceramic (efficiency of 52%), a considerably high CO2 amount among different materials. Therefore, the presence of water vapor strongly favored the CO2 chemisorption on Na2SiO3.