TITLE:
High Performance of Fly Ash Derived Li 4SiO4-Based Sorbents for High Temperature CO2 Capture
AUTHORS:
Shenggen Wu, Xiaoli Liang, Qi Zhang, Guiru Zhang
KEYWORDS:
Fly Ash, Lithium Orthosilicates, Molar Ratios, CO2 Capture
JOURNAL NAME:
Journal of Encapsulation and Adsorption Sciences,
Vol.11 No.1,
March
19,
2021
ABSTRACT: 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.