Effects of Drying Methods on Wet Chemistry Synthesis of Al-Stabilized CaO Sorbents for Cyclic CO2 Capture

Abstract

Al-stabilized CaO sorbents synthesized by wet chemistry methods have demonstrated effectiveness to mitigate CaO sintering during Ca-looping cycles (CaO + CO2 ⇌ CaCO3) for CO2 capture. To further screen the synthesis techniques and recipes, a series of Al-stabilized CaO sorbents, namely, CaO–Ca9Al6O18 hybrid materials, derived from cosolutions of calcium acetate and aluminum nitrate were prepared using three different drying methods, i.e., freeze drying, spray drying, and evaporation drying. These sorbents were then characterized by X-ray diffraction, N2 physisorption, scanning electron microscopy, and energy dispersive spectrometry. The effects of drying methods on the CO2 capture performance of the sorbents were analyzed comprehensively. Out of the three drying methods, spray drying enabled the optimal textural property and the hard skeleton with sufficient mechanical strength, resulting in the supreme CO2 capture capacity. Furthermore, it was found that, by spray drying, the inert spacer Ca9Al6O18 could...