Fabrication of yttrium-doped Li4SiO4 sorbents for CO2 capture and solar energy storage

High-temperature CO 2 capture based on Li 4 SiO 4 sorbents has been well recognized as an effective approach to mitigate the global warming issues. However, the relatively low sorption performance is one of the biggest challenges for the practical application. In the current investigation, Na- and Y-based dopants have been employed to enhance cyclic CO 2 sorption performance of Li 4 SiO 4 sorbents. Various physicochemical properties and cyclic CO 2 sorption performance of the prepared sorbents have been systematically studied. The results indicated that Na 2 CO 3 and Y 2 O 3 codoped Li 4 SiO 4 sorbent (Li 4 SiO 4 -10Na-15Y) exhibited excellent cyclic CO 2 capture performance with stable capacity of >0.27 g CO 2 /g sorbent (corresponding to the carbonation conversion of ∼96 %) during 15 sorption/desorption cycles. Even under lower CO 2 concentration and longer cycles, satisfying conversions of 85 % could be kept in the cyclic tests for the codoped Li 4 SiO 4 sorbent. In addition, the materials also showed high heat storage density of 557.8 kJ/kg and the performance was stabilized in the multicycle energy storage/release tests. The characterization results showed that the introduction of Y-based dopants induced triple positive effects for Li 4 SiO 4 including porosity creation, sintering-resistant ability, and producing Li 4 SiO 4 lattice defects. As a result, the enhanced specific surface area and reduced diffusion resistance were achieved and, thus, the CO 2 sorption performance including sorption capacity (heat storage density) and cyclic stability was obviously improved.