Author(s)

Shenggen Wu, Xiaoli Liang, Qi Zhang^*, Guiru Zhang

Department of Chemical Engineering, East China University of Science and Technology, Shanghai, China.

It is urgent to develop excellent solid CO₂ sorbents with higher sorption capacity, simpler synthetic process, better thermal stability and lower costs of synthesis in CO₂ capture and storage technologies. In this work, a number of Li₄SiO₄-based sorbents synthesized by lithium carbonate with three different kinds of fly ashes in various molar ratios were developed. The results indicate that the Li₂CO₃:SiO₂ mole ratio used in the sorbents synthesis significantly affects the CO₂ absorption properties. The sorption capacity increased with the excess of Li₂CO₃ first and then decreased when the excessive quantity was beyond a certain amount. The experiments found that FA-Li₄SiO₄_0.6, CFA-Li₄SiO₄_0.4, HCl/CFA-Li₄SiO₄_0.3 presented the best sorption ability among these fly ash derived Li₄SiO₄ samples, and the corresponding weight gain was 28.2 wt%, 25.1 wt% and 32.5 wt%, respectively. The three sorbents with the optimal molar ratio were characterized using various morphological characterization techniques and evaluated by thermogravimetric analysis for their capacity to chemisorb CO₂ at 450°C - 650°C, diluted CO₂ (10%, 20%) and in presence of water vapor (12%). The adsorption curve of FA- Li₄SiO₄_0.6 at different temperatures was simulated with the Jander-Zhang model to explore the influence of carbon dioxide diffusion on adsorption reaction. Further experiments showed that the adsorbent had a good sorption capacity in a lower partial pressure of CO₂ and the presence of steam enhanced the mobility of Li⁺. What’s more, FA-Li₄SiO₄_0.6, CFA-Li₄SiO₄_0.4 and HCl/CFA-Li₄SiO₄_0.3 particles showed satisfactory sorption capacity in fixed-bed reactor and excellent cyclic sorption stability during 10 sorption/ desorption cycles.

Fly Ash, Lithium Orthosilicates, Molar Ratios, CO₂ Capture

Wu, S. , Liang, X. , Zhang, Q. and Zhang, G. (2021) High Performance of Fly Ash Derived Li ₄SiO₄-Based Sorbents for High Temperature CO₂ Capture. Journal of Encapsulation and Adsorption Sciences, 11, 1-17. doi: 10.4236/jeas.2021.111001.