Effect of Li2SiO3 and Li8SiO6 components on multicycle CO2 capture performance of Li4SiO4

Li₄SiO₄, a high-temperature CO₂ capture material, has garnered significant attention due to its high adsorption capacity, but its cyclic stability still requires improvement. In this study, three different SiO₂ precursors, namely SiO₂ nanoparticles (SiO₂-NP), SiO₂ nanomesh (SiO₂-NM), and SiO₂ molecular sieves (SBA-15), were used as silicon sources to prepare Li₄SiO₄ materials for high-temperature CO₂ capture. The study found that the choice of SiO₂ precursor significantly impacts both the structure and adsorption performance of Li₄SiO₄. Using SiO₂-NP as the silicon source promotes the formation of Li₈SiO₆, which effectively increases the initial adsorption capacity of Li₄SiO₄-SiO₂-NP (34.79 wt%), but severely impacts its cyclic stability, with a capacity retention of only 23.99 % after 10 cycles. On the other hand, using SBA-15 as the silicon source promotes the formation of Li₂SiO₃, which effectively enhances the cyclic stability of Li₄SiO₄-SBA-15, with a capacity retention of 98.72 % after 10 cycles, though its initial adsorption capacity is only 28.20 wt%. However, using SiO₂-NM as the silicon source avoids the formation of Li₈SiO₆ while allowing for the generation of a small amount of Li₂SiO₃. The resulting Li₄SiO₄-SiO₂-NM sample exhibits excellent initial adsorption capacity (33.24 wt%) and good cyclic stability, with a capacity retention of 97.31 % after 10 cycles.