Enhancing the volumetric heat storage capacity of Mg(OH)2 by the addition of a cationic surfactant during its synthesis

Synthesis of Me Doped Mg(OH)2 Materials for Thermochemical Heat Storage

“…In this study, for a preliminary comparison, the samples were subjected to 3 cycles experiments. To be consistent with previous studies [ 17 , 22 , 23 , 25 ] the materials performances were expressed in terms of reacted fraction ( β (%)) defined by Equation (4): where Δ m real (%) was the instantaneous real mass change and Δ m th (%) was the theoretical mass change due to the dehydration of 1 mol Mg(OH) 2 , respectively expressed by Equations (5) and (6): where m in ( g ) and m inst ( g ) were respectively the initial sample mass and the instantaneous mass during TG analysis. While, M Mg ( OH )2 (g/mol) and M MgO (g/mol) were respectively the molecular weight of Mg(OH) 2 and MgO.…”

“…The almost general behavior of doped samples (MH-Ca and MH-Ni), in fact, reflects a higher density of the material and a lower value of the porosity, except for the MH-Ni1 sample, which morphology ( Figure 4 e) appears to be less stacked than the samples with the highest metal load and more similar to MH-Co1 and MH-Co2 ( Figure 4 h,i), which show a comparable pore volume (Entries 8 and 9 in Table 3 ). The same peculiar morphology was found for Mg(OH) 2 prepared in the presence of CTAB, which promotes the formation of well separated Mg(OH) 2 particles, lowering the hydroxide mean particle diameter and increasing the bulk density likely due to the peculiar stacked configuration of hydroxide particles, reported elsewhere [ 22 ].…”

“…The pelletized storage material, decreasing the tablets volume required to store the same amount of thermal energy of Mg(OH) 2 pellets of almost 13.6%, increases volume energy density [ 21 ]. In previous studies it was found that, synthesizing Mg(OH) 2 in presence of a cationic surfactant (cetyl trimethyl ammonium bromide—CTAB), an optimum CTAB concentration exists and it exhibits the highest volumetric stored/released heat capacity, ∼560 MJ/m 3 two times higher than that measured over Mg(OH) 2 prepared in absence of CTAB [ 22 ]. The purpose of this work is to investigate the influence of metal (Ca 2+ , Co 2+ and Ni 2+ ) doping in Mg(OH) 2 synthesis on its structural and morphological properties and consequently on its thermochemical behavior.…”

Comparison of the Effect of Coaddition of Li Compounds and Addition of a Single Li Compound on Reactivity and Structure of Magnesium Hydroxide

“…In previous studies, several additives, such as cetyl trimethyl ammonium bromide, lithium chloride, and lithium hydroxide-modified Mg(OH) 2 , have been shown to enhance the reactivity of Mg(OH) 2 . 11−15 In particular, LiCl-added Mg(OH) 2 and LiOH-added Mg(OH) 2 were much more efficiently dehydrated at 270–300 °C than pure Mg(OH) 2 . 12−14 Therefore, we believe that the Mg(OH) 2 /MgO system has a significant potential for thermal energy storage at 200–300 °C, which constitutes a large part of the industrial waste heat in Japan.…”

Tuning Mg(OH)2 Structural, Physical, and Morphological Characteristics for Its Optimal Behavior in a Thermochemical Heat-Storage Application

“…Aiming to achieve high efficiency Mg(OH) 2 synthesis production, Kim et al increased the MgO surface area by forming micro-beams on the surface of the millimeter-size MgO pellets by electron beam irradiation [ 34 ]. On the other hand, we enhanced the heat storage aptitude per volume unit of Mg(OH) 2 by adding the cationic surfactant CTAB (cetyl trimethylammonium bromide) during its synthesis, reaching, at an optimal CTAB concentration, the maximum volumetric stored and released heat capacity, ~560 MJ/m 3 [ 35 ], associated to a significant increase of specific surface area and mean particle size reduction. Despite Mg(OH) 2 /MgO systems for TES application having been studied also in larger-scale reactors [ 36 ], the results achieved so far still have the potential to be improved for the applicability of this material at the industrial level.…”