Self-reactivated mesostructured Ca-Al-O composite for enhanced high-temperature CO2 capture and carbonation/calcination cycles performance

In this study, highly efficient high-temperature CO2 sorbents of calcium aluminate (Ca–Al–O) mesostructured composite were synthesized using presynthesized mesoporous alumina (MA) as a porous matrix to react with calcium nitrate through a microwave-assisted process. Upon annealing at 600 °C, a highly stable mesoporous structure composed of poorly crystalline Ca12Al14O33 phase and the CaO matrix was obtained. The Ca–Al–O mesostructured sorbents with a Ca2+/Al3+ ratio of 5:1 exhibit an enhanced increasing CO2 absorption kinetics in the CO2 capture capacity from 37.2 wt % to 48.3 wt % without apparent degradation with increasing carbonation/calcination cycling up to 50 at 700 °C due to the strong self-reactivation effect of the mesoporous Ca–Al–O microstructure. Remarkable improvements in the CaO-CaCO3 conversion attained from the mesostructured Ca–Al–O composite can be explained using the concept combined with available mesoporous structure and Ca12Al14O33 phase content. However, a high Ca2+/Al3+ =8:1 Ca–Al...