Effect of Lithium Compound Addition on the Dehydration and Hydration of Calcium Hydroxide as a Chemical Heat Storage Material

Abstract

Many studies on calcium hydroxide [Ca­(OH)2] as a chemical heat storage material have been conducted. Generally, calcium hydroxide undergoes a dehydration reaction (heat storage operation) efficiently at about 400 °C or higher. In this study, we aimed to lower the dehydration reaction temperature and increase the dehydration reaction rate to expand the applicability of calcium hydroxide as a chemical heat storage material. For the purpose of improving the dehydration reactivity, calcium hydroxide with added lithium compounds was prepared, and the dehydration/hydration reactivities were evaluated. From the results, it was confirmed that the addition of the lithium compounds lowered the dehydration reaction temperature of calcium hydroxide and enhanced the reaction rate. The dehydration reaction of Ca­(OH)2 with Li compounds proceeded efficiently even at 350 °C, and the reversibility of the dehydration/hydration reaction was confirmed. The reason for the improvement of the calcium hydroxide dehydration reactivity upon the addition of a lithium compound was examined from the viewpoint of its crystal structure. It was presumed that when lithium ions enter the calcium hydroxide crystals, the crystals became fragile and the dehydration reaction was accelerated.

Fourier-transform infrared and X-ray diffraction analyses of the hydration reaction of pure magnesium oxide and chemically modified magnesium oxide

“…Salt hydrates such as MgCl 2 $6H 2 O, 14,15 LiOH$H 2 O, 16 and metal sulfates 15,[17][18][19] have been used as CHS materials in the temperature range of 100-250 C. Mg(OH) 2 , [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Ca(OH) 2 , 28,[35][36][37] and MgCO 3 (ref. 38) can be used to store energy in the temperature range of 200-500 C. These materials exhibit high energy density and the property of reversibility.…”

The Effect of Silica Sand Proportion in Laser Scabbling Process on Cement Mortar

“…The heat affected zone (HAZ) is a zone of the base material that was not melted but impacted by the heat generated during the laser scabbling process. According to Maruyama et al [22], the temperature for the dehydration reaction of Ca(OH) 2 is 400 • C or higher. From this study it was reported that microcracks occurred in cement-based materials due to the breaking of chemical and physical bonds caused by temperature.…”

“…From this study it was reported that microcracks occurred in cement-based materials due to the breaking of chemical and physical bonds caused by temperature. The dehydration of calcium hydroxide is shown in Equation (3) [22]:…”

Lithium compounds for thermochemical energy storage: A state-of-the-art review and future trends

“…The lithium salts used as dopants are listed in Table 2. As can be seen in the table, the main doping lithium-based salts are LiCl [63,64], LiOH [61,64], LiNO3 [65,66], Li4SiO4 [67] and LiKNO3 [62,68]. These salts have been used in multiple investigations, showing good thermal stability and expanding the applicability of the compounds as a heat storage materials.…”