Understanding the flue gas components on the mechanism governing CO2 adsorption on the Li4SiO4 surface

The development of novel Li 4 SiO 4 -based sorbents is hampered by a lack of understanding of the mechanisms governing CO 2 adsorption on the Li 4 SiO 4 surface. In this work, the adsorption of CO 2 and flue gas components (such as H 2 O and SO X (SO 2 and SO 3 )) on a simulated Li 4 SiO 4 surface was investigated using ab initio-based energetic calculations. The Li 4 SiO 4 surface was modeled by a cluster of lithium silicate, in which the atoms were unsaturated to simulate the active sites. Furthermore, Fourier transform infrared (FTIR) spectra were also analyzed. The calculated results showed that three possible configurations were determined: CO 2 weakly sorbed on the oxygen sites of Li 4 SiO 4 through physisorption; a carbonate species appeared, which was characterized by chemisorption; and a linear cluster of Li + -O = C=O formed, having the largest sorption energy. These three possible pathways were likewise in accordance with the FTIR results. Moreover, a pre-chemisorption of water on Li 4 SiO 4 resulted in promoted CO 2 capture, while the presence of competitive SO X sorption on the same active sites as CO 2 sorption showed an inhibition effect. The results clarify the complex adsorption mechanisms on the Li 4 SiO 4 surface. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901–1907, 2018