CO2 absorption on Na2ZrO3:: A kinetic analysis of the chemisorption and diffusion processes

The kinetics analysis of carbon dioxide (CO2) chemisorption on sodium zirconate (Na2ZrO3), which implies a sodium diffusion process, was investigated. Initially, Na2ZrO3 was analyzed by X-ray diffraction, scanning electron microscopy, and N-2 adsorption, to characterize the material. Finally, the material was thermally analyzed under a CO2 flux. Later, different isothermal experiments were performed under a CO2 flux to study kinetically the CO2 chernisorption on Na2ZrO3. Results showed that there is a sintering effect of the sample during the heating process. This effect produced, at low temperatures, a decrease in the CO2 chernisorption efficiency. However, at high temperatures, once the sodium diffusion was activated, the sintering effect did not interfere with the CO, chernisorption process. Modeling the CO2 chemisorption on Na2ZrO3 (in terms of a double process: chernisorption and sodium diffusion) allowed us to estimate the activation energy for these processes, 33 866 J/mol (chemisorption) and 48 009 J/mol (diffusion), which demonstrated that the diffusion process is the limiting step.