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

The development of novel Li4SiO4-based sorbents is hampered by a lack of understanding of the mechanisms governing CO2 adsorption on the Li4SiO4 surface. In this work, the adsorption of CO2 and flue gas components (such as H2O and SOX (SO2 and SO3)) on a simulated Li4SiO4 surface was investigated using ab initio-based energetic calculations. The Li4SiO4 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: CO2 weakly sorbed on the oxygen sites of Li4SiO4 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 Li4SiO4 resulted in promoted CO2 capture, while the presence of competitive SOX sorption on the same active sites as CO2 sorption showed an inhibition effect. The results clarify the complex adsorption mechanisms on the Li4SiO4 surface. (c) 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901-1907, 2018