A kinetic study of CO2 sorption/desorption of lithium silicate synthesized through a ball milling method

Abstract

Lithium silicates show high CO2 sorption capacity and excellent cyclic stability at high temperatures. Lithium orthosilicate was synthesized through a planetary ball milling route from LiOH and silica powder and was characterized for its structural and morphological features using TG, DSC, XRD, FTIR and FESEM techniques. Thermogravimetry was employed to study the CO2 sorption capacity of the synthesized sorbent under dynamic, isothermal and cyclic conditions. The material absorbed 30.5 % CO2 and retained its sorption capacity even after 10 cycles. The CO2 sorption and desorption kinetics of the synthesized sorbent were studied using Avrami–Erofeev method and Kissinger–Akahira–Sunose method respectively. The sorption of CO2 on lithium silicate took place by surface chemisorption and diffusion and activation energies required are 79 kJ mol−1 and 109 kJ mol−1 respectively. The activation energy for CO2 desorption increases with the progress in desorption from 91 kJ mol−1 to 146 kJ mol−1.