Enhanced Sorption Cycle Stability and Kinetics of CO2 on Lithium Silicates Using the Lithium Ion Channeling Effect of TiO2 Nanotubes

Lithium silicate (Li 4 SiO 4 ) is a promising high temperature CO 2 sorbent because of its large CO 2 capacity at elevated temperatures with low materials cost. However, the conventional nonporous Li 4 SiO 4 shows very poor CO 2 adsorption kinetics. Thus, a Li 4 SiO 4 –TiO 2 nanotubes complex was synthesized where LiOH and fumed silica would be calcined around TiO 2 nanotubes. TiO 2 nanotubes in Li 4 SiO 4 structure functioning as open highways, lithium ions were able to channel through the bulky structure and enhance the sorption kinetics, leading the total adsorption capacity to near theoretical values. Furthermore, cyclic studies at 700 °C revealed strong stability over at least 10 cycles. These findings indicate that stability and kinetics of CO 2 sorption can be greatly improved by the nanotube composites of known adsorbents.