Influence of the K-, Na- and K-Na-carbonate additions during the CO ₂ chemisorption on lithium oxosilicate (Li₈SiO ₆)

Lithium oxosilicate (Li₈SiO₆) was synthesized and mechanically mixed with potassium carbonate, sodium carbonate, or a mixture of both. While the product sample composition was characterized using X-ray diffraction, the CO₂ chemisorption was evaluated using dynamic (30-800°C), isothermal (350-650°C) and cyclic thermogravimetric analyses. The presence of the K, Na, or K-Na-carbonates in Li ₈SiO₆ changes the sorption properties in a wide temperature range. K-, Na-, K-Na-Li₈SiO₆ samples captured a maximum weight of 32 wt% at 400 °C, 42 wt% at 550 °C, and 38 wt% at 600 °C, respectively. The results revealed that the weight gained on Li ₈SiO₆ mixed with K-, Na- and K-Na-carbonates was attributed to the formation of the eutectic phases. These materials would be suitable for CO₂ capture over a wide temperature range depending on the application process. Nevertheless, the cyclic experiments showed important variations in their respective efficiencies, depending on the temperature.