Operando Raman spectroscopic studies of lithium zirconates during CO2 capture at high temperature

Abstract

Li₂ZrO₃ based sorbents were synthesized for CO₂ capture at high temperature between 500 and 700 °C. Monoclinic ZrO₂, tetragonal Li₂ZrO₃, Li₂CO₃, K₂CO₃ and LiKCO₃ phases were detected by XRD and Raman spectroscopy. The sorbents showed high stability and moderate capture efficiency. The addition of K resulted in the improvement of capture efficiency from 0.052 g CO₂ g mat⁻¹ in materials without K to 0.083 g CO₂ g mat⁻¹ in the doped solid. Here, we report an experimental setup of Raman spectroscopy coupled with online mass spectrometry and a demonstration of its capabilities using lithium zirconates as sorbents for high temperature CO₂ capture. Operando Raman spectroscopy allowed us to follow up the phase evolution during the capture process for the first time. The results obtained confirmed the presence of molten K and Li carbonates when the K-doped zirconates were exposed to CO₂ at 500 °C.