The effect of different exchangeable cations on the CO2 adsorption capacity of Laponite RD®
Résumé
Tri-octahedral clay minerals have a potential to be used as CO2 sorbents for intermediate temperatures (200-400 °C) owing to their thermal stability in this temperature range. In this study, laponite RD ® , a commercially synthesized hectorite (with Na+ as exchangeable cation) was used to investigate its capacity of CO2 adsorption at 200 °C and ambient pressure. Different cations such as Co2+ , Ni2+ , Mg2+ and Ca2+ were employed to exchange Na+ with the aim to study their effect on the capacity of adsorbing CO2. The commercial sample showed an adsorption capacity of 144 µmolCO2/g. Most of other exchanged sample displayed a deficit in the quantity of CO2 adsorbed. An exception was the Ca 2+ saturated sample, which exhibited a better performance (163 µmolCO2/g) compared to the Laponite RD ® . Thus, with higher affinity towards CO2, such sample could be a good candidate for CO2 capture. For all samples, most of 2 the CO2 was desorbed, and the formation of carbonate bonds was not observed by FTIR spectroscopy suggesting that the CO2 was mainly physisorbed.