Analysis of CO₂ sorption/desorption kinetic behaviors and reaction mechanisms on Li₄SiO₄

Abstract

The CO 2 sorption/desorption kinetic behaviors on Li 4 SiO 4 were analyzed. The theoretical compositions of the sorption/desorption reactions were calculated using FactSage. The sorption/desorption process on Li 4 SiO 4 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 Li 2 CO 3 and Li 2 SiO 3 . The whole desorption process is found to be controlled by the rate of the formation and growth of the Li 4 SiO 4 crystals. Furthermore, the influence of steam on the CO 2 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. © 2012 American Institute of Chemical Engineers AIChE J, 59: 901–911, 2013