In this work, a CaO/CeO 2 composite was used in a process that coupled the calcium looping for CO 2 capture and CaO/H 2 O thermochemical heat storage. A four fixed-bed reactor system was used to investigate the effects of cerium addition and calcination conditions of calcium looping on simultaneous CO 2 capture and thermochemical heat storage capacity of the composite in the coupled process. The interaction effect of the coupled process on the CO 2 capture and thermochemical heat storage capacity of the CaO/CeO 2 composite was determined. The addition of CeO 2 in the composite alleviates CaO sintering and promotes the diffusion of CO 2 and steam in the coupled process. The composite with a CeO 2 content of 10 wt % exhibits the highest simultaneous CO 2 capture and heat storage capacities in the coupled process. The hydration conversion of the composite that experienced 10 calcium looping cycles and then 10 heat storage cycles is 0.87 mol/mol, which is 1.3 times as high as that of the limestone under the same conditions. The composite from calcium looping under the mild calcination condition possesses greater heat storage capacity than that under the severe calcination condition. The introduction of the heat storage cycles in the CO 2 capture cycles apparently increases the CO 2 capture capacity of the composite because of the improvement in the pore structure. When CO 2 capture efficiency is 90%, the supply cost for the composite is lower, compared with that for limestone. The CaO/CeO 2 composite seems promising in the process that coupled calcium looping and CaO/H 2 O heat storage.

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CaO/Ca(OH) 2 thermochemical heat storage (THS) technology is considered to be one of the most promising technologies for large-scale solar energy storage. However, the THS performance of raw CaO-based materials decreases during multiple cycles. In this work, CaO derived from calcium acetate (Ac-CaO) is prepared and applied to a coupled system that achieved simultaneous CaO/Ca(OH) 2 THS and CO 2 capture. The CO 2 capture and THS performances of Ac-CaO are always higher than those of calcined limestone owing to the preferable pore structure, whereas Ac-CaO exhibits decreasing CO 2 capture and THS performance resulting from sintering and the formation of CaCO 3 from CaO or Ca(OH) 2 with ambient CO 2 during air cooling, respectively. In the coupled CaO/Ca(OH) 2 THS and CO 2 capture system, Ac-CaO is subjected to 10 CO 2 capture cycles, 30 THS cycles, 1 CO 2 capture cycle, 10 THS cycles, 1 CO 2 capture cycle, and 10 THS cycles sequentially. The hydration and dehydration conversions of Ac-CaO in the 31st THS cycle reach 91.7 and 93.6%, respectively, which are 1.6 and 1.6 times higher than those recorded prior to the 11th CO 2 capture cycle owing to the decomposition of CaCO 3 during calcination. The carbonation conversion of Ac-CaO achieves 89.9% in the 11th CO 2 capture cycle, which is 22.3% higher than that recorded prior to the 10 THS cycles owing to reactivation from the hydration process during THS. The CO 2 capture and CaO/Ca(OH) 2 THS processes are enhanced in the coupled system using Ac-CaO; therefore, the coupled system appears promising for CaO/Ca(OH) 2 THS and CO 2 capture.

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