The Effect of Na2ZrO3 Synthesis Method on the CO2 Sorption Kinetics at High Temperature

Abstract

Sodium zirconate (Na2ZrO3) can capture CO2 at high temperature with high efficiency. In this study, Na2ZrO3 sorbents were synthesized by wet-mixing and sol-gel methods. Both heated-drying and freeze-drying were applied for drying the solutions to form different porous structures in the prepared samples. The material characterization and cyclic sorption test were carried out, and the effects of synthesis methods and drying methods on the sorption properties of Na2ZrO3 were studied. The experimental results showed that Na2ZrO3 sorbents prepared by sol-gel mixing and freeze-drying possessed a more porous structure and smaller crystals, which favored the initial sorption rate of the materials. But sol-gel method and freeze-drying method could also reduce the content of monoclinic crystal in the sorbent, which limited the sorption of Na2ZrO3 in the later stage. Wet-mixing followed by heated-drying was unfavorable to porous structure, but the sample prepared via wet-mixing and heated-drying was the richest in monoclinic phase. Even though it captured CO2 at the slowest rate in the initial minute, the CO2 sorption by this sorbent was much more sustainable and the CO2 capacity was the highest over all the cycles. The findings in this study indicated that the content of monoclinic crystal form was the most important determinant of sorption performance. Seeking for highly porous property of Na2ZrO3 is not necessary.