2 research outputs found

    Self-Reactivated Mesostructured Ca–Al–O Composite for Enhanced High-Temperature CO<sub>2</sub> Capture and Carbonation/Calcination Cycles Performance

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    In this study, highly efficient high-temperature CO<sub>2</sub> 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 Ca<sub>12</sub>Al<sub>14</sub>O<sub>33</sub> phase and the CaO matrix was obtained. The Ca–Al–O mesostructured sorbents with a Ca<sup>2+</sup>/Al<sup>3+</sup> ratio of 5:1 exhibit an enhanced increasing CO<sub>2</sub> absorption kinetics in the CO<sub>2</sub> 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-CaCO<sub>3</sub> conversion attained from the mesostructured Ca–Al–O composite can be explained using the concept combined with available mesoporous structure and Ca<sub>12</sub>Al<sub>14</sub>O<sub>33</sub> phase content. However, a high Ca<sup>2+</sup>/Al<sup>3+</sup> =8:1 Ca–Al–O composite causes degradation because the pores become blocked and partial sintering induces CaO agglomeration
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