The following content is about using steam to activate CaO, aiming to enhance the stability of CaO for carbon capture. They are copied from an open access paper (https://doi.org/10.3390/ijerph7083129). It is clear that steam activation is an effective method to enhance the stability of CaO-based sorbents for CO2 capture.
” Our research on spent sorbent reactivation was based on experience with reactivation of sorbent utilized for SO2 retention [46–48]. Carbonation, like sulphation, is a gas-solid reaction with solid product formation at the surface of the reactant; therefore, similar limits and methods for reactivation were expected. An important difference is reversibility of carbonation, i.e., the product layer may be easily removed to expose sintered sorbent surface area to hydration. Taking into account the above analysis, sorbent hydration appears to be the most promising method for reactivation. It is based on a simple chemical reaction: CaO + H2O → Ca(OH)2. Considering the hydration technique, hydration by steam was chosen because there is no excess water to be removed, sample drying is not required and there is no loss of sorbent with liquid reactant [15].
“Figure 3. Steam reactivation effect on sorbent activity during carbonation in the TGA [15]. Kelly Rock limestone; 20 cycles (20% CO2, N2 balance, 650 °C, 30 min/100% N2, 850 °C, 30 min); reactivation by steam (saturated steam, 200 °C, 30 min); and carbonation in TGA (15% CO2, N2 balance, 700 °C).”
