CO2 absorption reaction of Li4SiO4 studied by the rate theory using thermogravimetry

Abstract

The CO2 absorption property of Li4SiO4 was investigated by thermogravimetry. Two kinds of sintered Li4SiO 4 samples were prepared at 700°C and 1000°C. The CO 2 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.