Vacuum assisted desorption of sodium zirconate sorbent for enhancing cyclic stability in pre-combustion CO2 capture

Abstract

Sodium zirconate (Na₂ZrO₃) is a promising material for pre-combustion CO₂ capture due to its fast sorption kinetics and excellent cyclic stability at high temperatures under ideal condition (desorption in 100% N₂). Still, there is a lack of study on the performance of Na₂ZrO₃ cyclic capture under harsh condition (desorption in high concentration CO₂). In this study, Na₂ZrO₃ was prepared by wet-mixing and heated-drying, and the difference in the cyclic CO₂ capture performance of the sample was compared between desorption under harsh condition and vacuum condition. The crystal structure of Na₂ZrO₃ was identified during the sorption-desorption cycles. The crystal structure was also modeled and simulated to analyze the reason for the superior capture performance from the monoclinic Na₂ZrO₃. It was found that the special interlocked and multilayered stacked structure of the monoclinic Na₂ZrO₃ allowed for high reactivity with CO₂. It was found that high temperature solely had little help in the desorption of Na₂ZrO₃ under harsh condition, but vacuum condition promoted desorption of Na₂ZrO₃ in high fraction CO₂, and vacuum desorption at 1000 °C-1050 °C resulted in Na₂ZrO₃ with both good capture performance and cycling stability. Vacuum desorption led to more complete reversion of Na₂ZrO₃ to the monoclinic state, benefiting for CO₂ capture. This study attempted to simulate the harsh capture environments of real industrial applications and to explore the possibility of Na₂ZrO₃ as a carbon capture material for pre-combustion capture.