Novel lithium-based sorbents from fly ashes for CO2 capture at high temperatures.

Abstract: In this work several Li₄SiO₄-based sorbents from fly ashes for CO₂ capture at high temperatures have been developed. Three fly ash samples were collected and subjected to calcination at 950°C in the presence of Li₂CO₃. Both pure Li₄SiO₄ and fly ash-based sorbents were characterised and tested for CO₂ sorption at different temperatures between 400 and 650°C and adding different amounts of K₂CO₃ (0–40mol%). To examine the sorbents performance, multiple CO₂ sorption/desorption cycles were carried out. The temperature and the presence of K₂CO₃ strongly affect the CO₂ sorption capacity for the sorbents prepared from fly ashes. When the sorption temperature increases by up to 600°C both the CO₂ sorption capacity and the sorption rate increase significantly. Moreover when the amount of K₂CO₃ increases, the CO₂ sorption capacity also increases. At optimal experimental conditions (600°C and 40mol% K₂CO₃), the maximum CO₂ sorption capacity for the sorbent derived from fly ash was 107mgCO₂/gsorbent. The Li₄SiO₄-based sorbents can maintain its original capacity during 10 cycle processes and reach the plateau of maximum capture capacity in less than 15min, while pure Li₄SiO₄ presents a continual upward tendency for the 15min of the capture step and attains no equilibrium capacity. [Copyright &y& Elsevier]