Sodium metasilicate (Na2SiO3): A thermo-kinetic analysis of its CO2 chemical sorption

Sodium metasilicate (Na2SiO3) was prepared by two different methods, solid-state reaction and precipitation. Then, samples were characterized by powder X-ray diffraction, scanning electron microscopy, N2 adsorption and thermogravimetric analysis. Thermal analyses showed that Na2SiO3 has the capacity to absorb small quantities of CO2 between room temperature and 130 °C. Modeling the surface reaction and sodium diffusion, the activation energies for these two processes were estimated to be 17,482 J/mol and 23,968 J/mol, respectively. Finally, the effect of the particle size, on the CO2 sorption, was found to be very important. The quantities of CO2 absorbed increased three times, when the particle size decreased and consequently the surface area increased.