CO2 Capture at High Temperature and Low Concentration on Li4SiO4 Based Sorbents

Abstract

Solid sorbents based on lithium orthosilicate (Li₄SiO₄) have shown promise for CO₂ capture at high temperature. Improved sorption properties can be obtained by appropriate doping. In this study, different promoted Li₄SiO₄-based sorbents were prepared by addition of potassium carbonate and binary/ternary alkali (Li, K and Na) carbonate eutectic mixtures. The CO₂ sorption properties of the sorbents were investigated by thermal gravimetric analysis (TGA) at different temperatures in the range between 500 and 600 °C and at low CO₂ partial pressure (0.04 atm). The results showed that all the promoters used noticeably improved the CO₂ sorption capacity in comparison to no-promoted Li₄SiO₄. At the optimum sorption temperature of 580 °C, Li₄SiO₄ with addition of 30 wt% of K₂CO₃ showed the best CO₂ adsorption proprieties with sorption capacities of 230 mg CO₂/g sorbent corresponding to a conversion of about 80 %. Besides this sample maintained its original capacity during multiple CO₂ sorption/desorption cycles.