Analysis of CO2 Sorption/Desorption Kinetic Behaviors and Reaction Mechanisms on Li4SiO4

The CO2 sorption/desorption kinetic behaviors on Li4SiO4 were analyzed. The theoretical compositions of the sorption/desorption reactions were calculated using FactSage. The sorption/desorption process on Li4SiO4 was investigated by comparing the shrinking core, double exponential, and Avrami-Erofeev models. The Avrami-Erofeev model fits the kinetic thermogravimetric experimental data well and, together with the double-shell mechanism, clearly explains the sorption/desorption mechanism. The sorption process is limited by the rate of the formation and growth of the crystals with double-shell structure consisting of Li2CO3 and Li2SiO3. The whole desorption process is found to be controlled by the rate of the formation and growth of the Li4SiO4 crystals. Furthermore, the influence of steam on the CO2 sorption process was analyzed. It has been observed that the presence of steam enhance the mobility of Li and, therefore, the rate of diffusion control stage. (C) 2012 American Institute of Chemical Engineers AIChE J, 59: 901-911, 2013