CO2 absorption property of Li4SiO4 was investigated by thermogravimetry under controlled P(CO2) between 1.0 bar and 2x10-2 bar. By using scanning type TG, equilibrium temperature of chemical reaction described as Li4SiO4+CO2↔Li2CO3+Li2SiO3 at fixed P(CO2) could be evaluated. The obtained equilibrium temperature and P(CO2) by using particle with small diameter showed fair agreement with thermodynamically calculated ones. CO2 absorption rate increased with increasing temperature or P(CO2) and decreasing particle size. Under P(CO2) larger than 0.3 bar, reaction kinetics could be explained with Jander model assuming Li+ diffusion as rate determining step. With decreasing P(CO2) as small as 0.03 bar, it was suggested that reaction model varied to one with surface reaction as rate determining step.
Keywords:Li4SiO4, CO2 absorbent, Thermogravimetry, Ellingham diagram, CO2 absorption kinetics
Publication Date: 2018-04-25