Different sodium zirconate solid solutions containing aluminum (Na 2 (Zr 1−x Al x )O 3 ) were synthesized via a solid-state reaction. Samples were characterized using X-ray diffraction and solid-state nuclear magnetic resonance. Then, samples were tested as CO 2 captors. Characterization results show that aluminum ions can occupy zirconium or sodium sites in the Na 2 ZrO 3 structure. Thus, the aluminum dissolution is compensated by different structural defects. The CO 2 capture evaluation shows that the aluminum presence into the Na 2 ZrO 3 structure improves the CO 2 chemisorption within certain aluminum content under specific thermal conditions. These results were corroborated with the kinetic analysis, where the activation enthalpies were determined. The CO 2 chemisorption differences were attributed to different sodium secondary phases produced in each case and their corresponding diffusion properties. Finally, cyclic performance tests indicate that Na 2 (Zr 1−x Al x )O 3 ceramics exhibited high and stable CO 2 capture behaviors.

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To determine the influence of the aluminum content in the sodium zirconate during the CO 2 chemisorption process, specific compositions in the Na 2 (Zr 1−x Al x )O 3−x/2 solid solution were produced. The synthesis was performed in order to restrict the aluminum crystalline sites to tetrahedral positions, substituting zirconium atoms. Samples were characterized using Xray diffraction, N 2 adsorption−desorption and 27 Al solid-state nuclear magnetic resonance. Then, samples were tested as CO 2 captors using dynamic and isothermal analyses. Additionally, ionic conduction experiments were performed in different sodium containing phases to determine the effect of these phases in the CO 2 chemisorption process. Results showed that there are several factors that determine the CO 2 chemisorption in the pristine Na 2 ZrO 3 and compounds of the Na 2 (Zr 1−x Al x )O 3−x/2 solid solution. Some of these factors are the presence or absence of different structural vacancies, as well as the presence of different phases in the carbonated external shell.

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