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Cyclic CO2adsorption by using MgO as a sorbent at low temperatures is considered a promising route for postcombustion CO2capture. However, most MgO-based sorbents are in the form of fine powder and cannot be used in a fluidized bed reactor, and at the same time, suffer from a rapid loss in CO2uptake capacity due to the decrease of surface area aroused by pore shrinking and grain sintering. In this study, mesoporous silicas with highly ordered pore structures have been used as binders, for the first time, to fabricate MgO-based sorbent pellets via a simple and scalable extrusion–spheronization approach. The obtained MgO-based pellets exhibit high porosity attributed to the nature of the mesoporous binder, leading to a significantly increased stability and CO2uptake capacity. Especially for the low-concentration CO2that is comparable to the flue gas from a coal-fired power plant, the results show that the ordered mesoporous silica binder provides a remarkable promotion effect and excellent stability in the capture performance. The CO2uptake capacity of the best-performing sorbent, 20-KIT-6–100, displays a small decline of 6.86% (from 1.02 mmol of CO2/g in the first cycle to 0.95 mmol of CO2/g in the 10th cycle). It is envisaged that mesoporous materials hold great potential to be used as binders in reinforcing the metal oxide-based sorbents for flue-gas CO2capture in practical applications.

CuFe2O4is an emerging high-performance oxygen carrier for chemical looping combustion (CLC), which is hailed as the most promising technology to reduce combustion-derived CO2emission. CuFe2O4oxygen carriers with minute structural differences could be largely divergent in the reactivity for the CLC process, which seems not to raise much concern by either experimental or computational studies. Herein, based on density functional theory (DFT) calculations, we compare the performance of three well-documented CuFe2O4configurations as oxygen carriers in the CLC process and relate the reactivity difference to their structural nuances. The reaction mechanisms of representative CLC reactants (i.e., CH4, H2, and CO) over different CuFe2O4configurations are explored in-depth. DFT calculations indicate that among different CuFe2O4configurations, the distribution, orientation, and activity of the O/Cu/Fe sites vary largely over the respective CuFe2O4(100) surfaces, thus affecting the adsorption and oxidation of CLC reactants. Fe atoms, especially in configuration 3, are observed to exhibit a higher degree of exposure and afford lower steric hindrance to interact with CH4and H2, thereby facilitating higher adsorption energies and lower dissociation energy barriers correspondingly. The Fe–Cu synergistic effect is revealed to promote the dissociation reaction of both CH4and H2. CO exhibits direct oxidation to CO2over the O sites, which generally exhibit higher CO binding energies than Cu/Fe sites. Particularly, O sites in configuration 3 are observed with generally lower oxygen vacancy formation energy as well as steric hindrance, thus affording the oxidation of CO in a more facile way. The structure–performance relationship revealed in this work is of positive significance for the design of high-performance spinel CuFe2O4oxygen carriers.