Cyclic CO2 chemisorption-desorption behavior of Na2ZrO3: Structural, microstructural and kinetic variations produced as a function of temperature

A structural, microstructural and kinetic analysis of the Na2ZrO3-CO2 system was performed over 20 chemisorption-desorption cycles. Different cyclic experiments were performed between 500 and 800 degrees C. Although the best results were obtained in Na2ZrO3 sample treated at 550 degrees C, all the samples treated between 500 and 700 degrees C presented good CO2 chemisorption efficiencies and stabilities. On the contrary. Na2ZrO3 sample treated at 800 degrees C presented a continuous decrement of the CO2 chemisorption. After 20 cycles all the samples presented a partial Na2ZrO3 decomposition, determined by the ZrO2 formation, which was associated to sodium sublimation. Additionally, the Na2ZrO3 microstructural analysis showed a systematic morphological evolution. It was microscopically observed that Na2ZrO3 particles tend to fracture due to the Na2CO3 formation. Later, after several cycles these tiny fractured particles sinter producing new polyhedral and dense Na2ZrO3-ZrO2 particles. Finally, an exhaustive kinetic analysis showed a high CO2 chemisorption-desorption stability at different temperatures. (C) 2013 Elsevier Inc. All rights reserved.