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 degrees C. N-2 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 degrees 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. (C) 2014 Elsevier B.V. All rights reserved.