CaO/H₂O Thermochemical Heat Storage Capacity of a CaO/CeO₂ Composite from CO₂ Capture Cycles

Abstract

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.

Review on the modifications of natural and industrial waste CaO based sorbent of calcium looping with enhanced CO2 capture capacity

“…Then, adding cerium (IV) oxide, CeO 2 exhibits high CO 2 capture capacity (0.72 g CO 2 /g sorbent), which slowly decreases to 0.65 CO 2 /g sorbent after 10 cycles due to its anti-sintering properties [ 127 ]. In addition to high CO 2 capture capacity, doped CeO maintains the stability of limestone after several cycles.…”

Calcium carbide residue – a promising hidden source of hydrogen

“…[55][56][57] In 2021, the production of calcium carbide amounted to more than 27 million tons, while more than 75% was used for the production of acetylene, 58 thereby approximately 23 million tons of CCR were produced. Of course, CCR can be used for soil stabilization, [59][60][61][62][63] as a cementing agent and binder, [64][65][66][67][68] for CO 2 capture, [69][70][71][72] and in chemistry. [73][74][75][76] However, the consumption of CCR is still too low to utilize all the collected and newly generated CCR, and therefore the rest of the carbide sludge is simply disposed of, polluting the environment.…”

Alkali Metal Nitrates Promoted MgO Composites with High CO2 Uptake for Thermochemical Energy Storage

“…5,20,24 Ca(OH) 2 /CaO shows promise for harvesting heat in the range of 450−550 °C, but its potential in medium-temperature heat storage is limited. 22…”

“…Compared to the wide attention dedicated to high-temperature TCES in CSP plants, harvesting and storage of industrial waste heat from exhaust gases (150–400 °C) has been overlooked. Mg­(OH) 2 /MgO, MgSO 4 ·7H 2 O/MgSO 4 , and Ca­(OH) 2 /CaO have been explored as thermochemical materials for low–medium temperature heat storage. − MgSO 4 ·7H 2 O/MgSO 4 is suitable for recovering low-temperature heat (<100 °C), while its application has been restricted by the low reversibility and long period of the hydration–dehydration process. ,, Ca­(OH) 2 /CaO shows promise for harvesting heat in the range of 450–550 °C, but its potential in medium-temperature heat storage is limited. , …”