Particle size depenclence of CO2 absorption rate of powdered Li4SiO4 with different particle size

Particle size dependence Of CO2 absorption rate of powdered Li4SiO4 with four kinds of particle sizes was studied by SEM observation, particle size distribution measurement, and thermogravimetry. Average particle sizes of the powdered single phase Li4SiO4 samples were estimated about 26 mu m, 34 mu m, 53 mu m, 70 mu m, respectively by the particle size distribution measurement and SEM observation. The measurement of apparent rate constant k for the CO2 absorption reaction showed that k values of all the powdered Li4SiO4 samples increase with the increasing measurement temperature T, following the Arrhenius equation in the region of 620-660 degrees C, while the k values abruptly increase deviating the Arrhenius equation over 670 degrees C. It was also noted that the k values seem to depend on the particle size of the powdered Li4SiO4 samples, that is, the k values increase with the decreasing particle size. Moreover, difference between the k values of all the powdered samples at same temperature was found small in the region of 620-660 degrees C, while the difference was found large over 670 degrees C. For Li4SiO4 with smaller particle size, Delta k = k(700 degrees C) - k(660 degrees C) was found larger, vice versa, the Delta k was found smaller for Li4SiO4 with larger particle size. The values seem to correspond with reaction mechanism for CO2 absorption of Li4SiO4 particle. (c) 2008 The Ceramic Society of Japan. All rights reserved.