(253h) Studies on the Self-Activation Mechanism of Lithium-Based Sorbent for Enhancing Its Sorption Capacity

In this work, the self-activation behaviours of the lithium-based sorbent were studied. It is found that compared with that of Li₄SiO₄, the capacity of K-doped Li₄SiO₄ sorbent was largely improved after several absorption-desorption cycles. A series of characterization methods were performed and the results showed that the pore widening occurred on the K-doped Li₄SiO₄ sorbent during cycling. This phenomenon that the sorption capacity increases with cycling was defined as self-activation. It was also found that the key point of this self-activation process was the existence of the eutectic compound, because during cycling, the eutectic compound enhances the CO₂ diffusion and large pores were formed. The pore widening during activation process was proved to be beneficial to the sorption ability by reducing the CO₂ diffusion resistance, for the capacity of 20-40 mesh activated K-doped Li₄SiO₄ sorbent (c.a. 5.0 mmolCO₂/g sorbent) is quite similar with that of the fine powder sorbent (c.a. 5.2mmol/g). Furthermore, the activated sorbent showed superior sorption ability under critical conditions, nearly 20 times that of the untreated one at 450°C under 10vol% CO₂ atmosphere. Finally, the activated K-doped Li₄SiO₄ sorbent present excellent cyclic performance, indicating its good application prospect.