Citrate Sol–Gel Method for the Preparation of Sodium Zirconate for High-Temperature CO₂ Sorption

Abstract

The use of sorbents capable of capturing high-temperature CO2 increases the overall efficiency of CO2 removal processes, without the need for cooling the flue gases. In this study, Na2ZrO3 for high-temperature CO2 sorption was newly prepared using a citrate sol–gel method. The characteristics and CO2 sorption behavior of the prepared Na2ZrO3 were examined by field-emission scanning electron microscopy, N2 adsorption analysis, X-ray diffraction, and thermogravimetric analysis, and compared with those of Na2ZrO3 synthesized using a conventional solid-state method. Na2ZrO3 could be synthesized at lower temperature by using the citrate sol–gel method compared to the case of solid-state method. Na2ZrO3 prepared using the citrate sol–gel method showed excellent CO2 sorption performance: high sorption capacity (17.5–21.0 wt % at 823 K and 1 bar), fast sorption kinetics, and good cycling stability. Kinetic analysis was also conducted by fitting the CO2 sorption behavior to the double exponential model.