CO2 Absorption Reaction of Li4SiO4 studied by the Rate Theory using Thermogravimetry

The CO2 absorption property of Li4SiO4 was investigated by thermogravimetry. Two kinds of sintered Li4SiO4 samples were prepared at 700°C and 1000°C. The CO2 absorption rate of the powdered Li4SiO4 samples was measured in 100 vol% CO2 atmosphere at nine selected temperatures in the 620~700°C region, and the measured data were discussed by the rate theory. The CO2 absorption reaction of the Li4SiO4 would be a pseudo first order reaction. For these samples, apparent reaction rate constants k were measured at different measurement temperatures, and activation energies were estimated by the Arrhenius plot. For both the samples, the estimated activation energies were about 115 kJ/mol in the 620-660°C region and about 56 kJ/mol in the 680-700°C region. The large difference between these activation energies seems to depend on the surface state of the Li4SiO4 particle reacting with CO2.