Adsorption study of CO2 on Li4SiO4 nanoparticle via reactive molecular dynamics

Abstract

CO2 emission has been severe environmental issue for several decades due to global warming, and recently lithium silicates have been considered as a promising adsorbent for CO2 capture. In this study, we investigated CO2 adsorption mechanism on Li4SiO4 at high temperatures (500~650 ℃) using reactive molecular dynamics simulation (i.e. using ReaxFF). First, we developed ReaxFF parameters compatible for bulk and surface systems of Li4SiO4, Li2SiO3, Li2CO3 and optimized the parameters comparing with quantum mechanics (QM) results. With the optimized parameters, we checked phase transition of Li4SiO4, Li2SiO3 and Li2CO3 surface depending on temperature. Second, we observed CO2 adsorption on Li4SiO4 thin layer at different temperatures. In these reactions, we predict thin bilayer and double shell formation on Li4SiO4 surface after CO2 adsorption. In addition, multilayer system (Li4SiO4-Li2SiO3-Li2CO3) was modeled to observe the diffusion of Li+ and O2- ions after thin bilayer formation. The thermal conductivity was estimated by analyzing the temperature profile. Finally, in order to investigate the overall reaction mechanism, we performed time-dependent CO2 adsorption simulation of Li4SiO4 spherical nanoparticle.