Enhancement of CO₂ Absorbance for Lithium Ferrite—Combinatorial Application of X-Ray Absorption Fine Structure Imaging

Abstract

Lithium ferrite powder was prepared at quite a low temperature by solid-state reaction, and its performance as a CO₂ absorbent was tested. In order to evaluate its performance efficiently, the idea of combinatorial-material development was introduced and combined with novel X-ray fluorescence (XRF) imaging analysis. The XRF of multiple samples on a combinatorial substrate were observed in parallel—and therefore in a short space of time—thus enabling the X-ray absorption fine structure (XAFS) of the samples to be compared with one another. Thermogravimetry (TG) was also used to estimate the absorption speed and absorbing mass of CO₂ quantitatively. The X-ray diffraction pattern showed that the obtained lithium ferrite was mainly α-LiFeO₂, and the broadening of the lines suggested a nano-crystalline product. LiFeO₂ reacted with CO₂ to form Li₂CO₃ and γ-Fe₂O₃. Changes in the XAFS spectra and the weight changes observed by TG with CO₂ exposure showed quick and voluminous absorbance by the low-temperature synthesized sample, and a higher performance was confirmed compared with samples prepared by the conventional ceramic method.