Understanding the competition between carbonation and sulfation of Li4SiO4-based sorbents for high-temperature CO2 capture

High-temperature CO 2 adsorption is an important method in reducing the excessive CO 2 emissions for the mitigation of global climate change. As a potential high-temperature CO 2 sorbent, Li 4 SiO 4 attracted extensive concern due to its high CO 2 capacity with excellent stability. However, gas impurities in industrial flue gas, especially SO 2 affect the CO 2 adsorption process, and the competition between SO 2 and CO 2 during the adsorption process by Li 4 SiO 4 is lack of understanding. This work studied the competitive behavior between carbonation and sulfation through experimental tests, characterizations, and DFT calculations. Results show that carbonation can slightly inhibit the proceeding of sulfation while sulfation almost prevents the occurrence of carbonation for both Li 4 SiO 4 and K-Li 4 SiO 4 . In addition, the doping of K 2 CO 3 in Li 4 SiO 4 is observed to significantly promote both the carbonation and sulfation process. Furthermore, stable adsorption structures of CO 2 and SO 2 on Li 4 SiO 4 were obtained via DFT calculation, which verifies the mutual inhibition between carbonation and sulfation. These results provide a well understanding of the competition between carbonation and sulfation of Li 4 SiO 4 -based sorbents, and are helpful for the design and optimization of CO 2 adsorption process.