Synthesis, kinetic study, and reaction mechanism of Li4SiO4 with CO2 in a slurry bubble column reactor

This study was performed to investigate the synthesis, kinetic and reaction mechanism of Li4SiO4 with CO2 in a slurry bubble column reactor. The Li4SiO4 powder sample was prepared via a solid-state reaction. The sample was characterized via X-ray diffraction (XRD) analysis and verified as a single phase. The median diameter of the sample was measured using the laser diffraction and scattering method as about 20 mu m. The synthesized sample was suspended in binary molten carbonate of Li2CO3-K2CO3 having a molar ratio of 38:62. The experimental results show that Li4SiO4 in the slurry bubble column absorbed approximately a stoichiometric amount of CO2. The kinetic study shows that the CO2 reaction behavior on the Li4SiO4 surface was fitted to a double exponential model and the limiting step of the reaction was lithium diffusion. The mass transfer coefficient of CO2 and rate constant of reaction with Li4SiO4 were studied to understand the overall absorption mechanism in the reactor. The resistance for the direct reaction of CO2 on the Li4SiO4 was much smaller than the resistance for the mass transfer of CO2 to the Li4SiO4. We can conclude that the direct contact of CO2 with Li4SiO4 was the main path for the reaction.