Effect of a Li2SiO3 phase in lithium silicate-based sorbents for CO2 capture at high temperatures

Abstract

The Li4SiO4 sorbent is considered one of the most promising CO2 acceptor materials at high temperatures, but it has the disadvantage of poor CO2 capture performance due to aggregation. In this study, a novel lithium silicate-based sorbent containing both Li4SiO4 phase and Li2SiO3 phase was developed to overcome the decrease of CO2 capture capacity of the sorbent for CO2 capture in the high temperature range of 550–700 °C. This sorbent was simply prepared by physical mixing of Li2CO3 and SiO2 (Ludox®) in a 1.8:1 M ratio. The effect of the developed lithium silicate-based sorbent on CO2 capture was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature-programmed desorption (TPD) analysis. The novel lithium silicate-based sorbent exhibited a high CO2 capture capacity (∼250 mg CO2/g sorbent) during multiple cycles at a regeneration temperature of 700 °C. In addition, we found that the CO2 capture performance was affected by Li2SiO3 phase in the lithium silicate-based sorbents. This is because the Li2SiO3 in the sorbent helps prevent growth of particle size and aggregation.