Coupled CO₂ capture and thermochemical heat storage of CaO derived from calcium acetate

Abstract

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.

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

“…Acetic acid (AA) is commonly used as a modifier of limestone. The carbonation conversion of modified acetic acid is 2.33 higher than unmodified calcined limestone [ 108 ] and higher than other organic acids during the initial cycle [ 109 ]. This characteristic contributes to a high porous surface and small grain size due to the decomposition of calcium acetate into acetone, CO 2 and CaO [ 108 ].…”

“…The carbonation conversion of modified acetic acid is 2.33 higher than unmodified calcined limestone [ 108 ] and higher than other organic acids during the initial cycle [ 109 ]. This characteristic contributes to a high porous surface and small grain size due to the decomposition of calcium acetate into acetone, CO 2 and CaO [ 108 ]. Moreover, modified limestone with AA as sorbent can reduce the energy penalty when integrating with a power plant.…”

A Dual Modification Method to Prepare Carbide Slag into Highly Active CaO-Based Solar Energy Storage Materials

“…These results proved that calcium-based materials with acetic acid addition have richer pore structures, larger specific surface area, and pore volume compared with no acetic acid addition. 37 Sun et al 38 found that the energy storage performance of CaO prepared from calcium acetate was always higher than that of CaO prepared from limestone. Li et al 39 prepared CaO by using the thermal decomposition of calcium acetate to obtain higher CaO conversion.…”