Microstructural Thermal Evolution of the Na2CO3Phase Produced during a Na2ZrO3–CO2Chemisorption Process

Na 2 ZrO 3 was synthesized by a solid-state reaction, and a CO 2 chemisorption process was evaluated as a function of temperature to determine whether structural and/or microstructural modifications occurred during the reaction process. This study was performed using the following techniques: thermogravimetry, X-ray diffraction, scanning and transmission electron microscopy, and N 2 adsorption. The results clearly show that Na 2 CO 3 –ZrO 2 was produced on the external shell of Na 2 ZrO 3 during the CO 2 chemisorption process. The microstructural properties varied as a function of temperature. The Na 2 ZrO 3 –CO 2 chemisorption reaction was not limited at T ≤ 550 °C because the Na 2 CO 3 –ZrO 2 external shell contained mesopores. CO 2 diffused through the mesoporous shell, and the reaction continued. Conversely, if the CO 2 chemisorption occurred at T > 550 °C, the mesoporosity on the Na 2 CO 3 –ZrO 2 external shell was not observed, and the chemisorption was kinetically controlled by the diffusion of CO 2 through the sodium crystal phases.