Comparative study of lithium-based CO2 sorbents at high temperature: Experimental and modeling kinetic analysis of the carbonation reaction

Abstract

This work focuses on the study of the CO2 capture kinetic properties and reactivity of different alkali-based sorbents. Three samples, K-doped Li2ZrO3, mixed Li2ZrO3-Na2ZrO3, and Li4SiO4, were characterized and evaluated by thermogravimetric analysis under different reaction conditions. The presence of alkali zirconate and silicate phases was confirmed by XRD and Raman spectroscopy. The Li-Na zirconate showed the fastest initial reaction rates and the strongest dependence on the temperature, while the K-doped Li zirconate presented a higher dependence on the CO2 concentration. The activation energies derived from the modeling with the double exponential and the Avrami Erofeev model were consistent with the calculated apparent activation energy. Finally, the phase evolution followed by operando Raman Spectroscopy during the capture process was in agreement with the kinetic analysis, confirming the higher reactivity of the Li4SiO4 and Li-Na zirconate derived samples.