Novel Na-silicates CO2 Sorbents from Fly Ash

Despite the very good CO2 uptake of lithium based silicates at high temperature, this material is expensive and not very abundant. Therefore, there is the need to develop high temperature sorbents based on low-cost and widely available materials. In this work, Na-silicates prepared by mixing sodium carbonate with fly ash (FA) in the molar ratio of Na2CO3:SiO2 of 1:1 and 4:1 were evaluated for their capacity to chemisorb CO2 at 700 °C. This temperature was chosen as it is compatible with post-combustion technologies. Pure Na-FA sorbent (NaCO3:SiO2 molar ratio of 1:1) was able to adsorb 1.8 mmol CO2/g sorbent. The CO2 uptake capacity increased to 2mmol CO2/g sorbent in presence of 20% Li2CO3 as additive. Therefore, this work suggests that Na-silicate materials with acceptable CO2 uptake can be developed as high temperature sorbents for post-combustion technologies.