Easy fabrication method of Li₄SiO₄-K₂CO₃ based pellets for CO₂ capture at high temperature

This study focuses on a novel fabrication method of K₂CO₃-Li₄SiO₄ based sorbents for CO₂ capture from hot flue gas of gas turbines. The developed pellets were produced by sintering K₂CO₃-Li₄SiO₄ powders at 550 ◦C using viscous polyalphaolefins as pore formers. This mild calcination temperature was selected as the optimal condition for the development of a suitable porosity preventing powder degradation which typically occurs at higher temperatures. The sorption/desorption performance was tested by thermogravimetric analysis conducted at 580 ◦C under 0.04 atm of CO₂ and 620 ◦C under 1 atm of N₂, respectively. Results showed that the use of 20 wt% K₂CO₃ represents the optimal content to achieve a stable formation of molten eutectic K₂CO₃-Li₂CO₃ mixture during CO₂ chemisorption, while avoiding K₂CO₃ crystals phase segregation during multiple sorption cycles. In addition, the use of 30 wt% olefin allowed the development of resistant and porous pellets of tuneable dimension and shape with a stable sorption capacity up to 130 mgCO₂/g obtained over 25 multiple cycles of 30 min each. The present research lays the groundwork for the adoption of a novel pelletizing technique to produce innovative sorbents with enhanced CO₂ capture and cycling capabilities, manufactured via a simple and more sustainable approach.