A highly efficient CaO-based CO2 sorbent prepared by a citrate-assisted sol–gel technique

This work describes the development of an efficient Al-stabilized CaO sorbent for CO2 capture. The sorbent (92.5 wt% CaO/7.5 wt% Al2O3) was prepared using a citrate-assisted sol–gel technique followed by calcination in two steps, under inert and air atmospheres. The material was tested over 31 cycles of carbonation–calcination under mild and severe operating conditions. Under mild calcination condition (800–900 °C. N2 flow), the working adsorption capacity was 0.57 g-CO2/g-ads over 31 cycles without any deactivation. The high stability was attributed to the favorable structural properties and high dispersion of Ca9Al6O18 binder throughout the CaO matrix. Moreover, a number of parametric studies were performed to investigate the influence of carbonation and calcination temperatures on the activity of the material. Application of severe calcination condition (930 °C in the presence of 100% CO2) yielded an uptake of 0.33 g-CO2/g-ads at the end of operation, indicating the superior activity and stability of the current material in comparison to previously reported Al-stabilized CaO adsorbents operated under similar conditions.