“As shown in , the equilibrium temperatures of absorption and regeneration increase as the CO2 partial pressure rises monotonously. In other words, each equilibrium temperature corresponds with a partial pressure of CO2 in the absorption atmosphere. Essaki et al. [77] reported that when the absorption temperature of Li4SiO4 pellets provided by Toshiba varied from 400 to 600 °C in 5 vol.% CO2, and results showed that weight increase at 500 °C was 20 wt.%, which was much higher than those at 400 °C and 600 °C. Additionally, Quinn et al. [81] reported that 625 °C was the most appropriate temperature for the absorption of Toshiba-provided Li4SiO4 pellets in a pure CO2 atmosphere. This confirmed the conclusion that the equilibrium temperature of the reaction between Li4SiO4 and CO2 rises with increasing CO2 partial pressure.
Different kinds of Li
4SiO
4 materials accommodate diverse appropriate absorption temperatures. Qiao et al. [
60] synthesized Li
4SiO
4 material from RHA and Li
2CO
3, and they found that the most suitable temperature for absorption was 650 °C in a pure CO
2, while Puccini et al. [
78] reported that 580 °C was the optimum temperature for K-doped Li
4SiO
4 materials, and Wang et al. [
30] pointed out that 575 °C was the most appropriate for the CO
2 absorption by Li
4SiO
4.
Temperature during the regeneration process also had a deep effect on CO
2 absorption performance on Li
4SiO
4 material. Ochoa-Fernández et al. [
80] reported that the ratio and degree of regeneration increased when the regeneration temperature rose from 525 to 575 °C. This indicates that a higher regeneration temperature is possibly advantageous for the regeneration of Li
4SiO
4 material, while too high a regeneration temperature intensifies the sintering of the material, which is extremely harmful.”
