CO2 Absorption/Release Properties of Lithium Zirconate Powder Prepared by the Sol-Gel Process

The sol-gel synthesized powder was a single phase Li2ZrO3. This synthesized powder reacted with CO2 at temperatures from the ambient temperature to a high temperature. The reaction products reacted reversibly to form Li2ZrO3 at temperatures above 925 K. The degree of absorption was defined as the value obtained by dividing the fractional mass gain of Li2ZrO3 after absorption by the fractional mass gain corresponding to a 100% reaction. Consequently, the degree of absorption was determined to be 95.2% under the absorption condition of 773 K and 7.2 ks. When CO2 absorption at 773 K and release at 993 K were repeated five times to examine the cyclic behavior, the degree of absorption was almost the same as the initial amount. The degree of absorption of commercial powder prepared by a solid-solid reaction of Li2CO3 and ZrO2 was 10.6% under the same absorption condition. The degrees of absorption with the sol-gel synthesized powder were determined to be 26, 31 and 43% under the absorption conditions of 293, 313 and 333 K for an exposure time of 115.2 ks. The absorption behavior could be best explained by an intraparticle diffusion mechanism. The diffusion of CO2 gas through the reaction product with an apparent activation energy of 24 kJ·mol−1 was a rate-determining step of the absorption reaction.