Experimental Study of Hydration/Dehydration Behaviors of Metal Sulfates M2(SO4)3 (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) in Search of New Low-Temperature Thermochemical Heat Storage Materials
Experimental Study of Hydration/Dehydration Behaviors of Metal Sulfates M2(SO4)3 (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) in Search of New Low-Temperature Thermochemical Heat Storage Materials
复制标题
DOI：
10.1021/acsomega.9b04308
复制
发表时间：
2020-06
期刊：
影响因子：
4.1
通讯作者：
Kunihiko Shizume;Naoyuki Hatada;T. Uda
中科院分区：
文献类型：
--
作者：
Kunihiko Shizume;Naoyuki Hatada;T. Uda
为了确定潜在的低温热化学储热材料，用热重法研究了M_2(SO_4)_3(M=Sc，Yb，Y，Dy，Al，Ga，Fe，In)的水合/脱水反应。这些材料具有相同的菱面体晶体结构，其中一种是菱面体Y2(SO4)3，最近被认为是一种很有前途的材料。所有的M2(SO4)3·xH2O在30℃到200℃之间，在相对较低的pH_2O(=0.02atm)下可逆脱水。其中，稀土(RE)硫酸盐RE2(SO4)3·xH2O(RE=Sc，Yb，Y，Dy)表现出较窄的热滞(小于50℃)，表明它们的反应速率比其他硫酸盐M2(SO4)3·xH2O(M=Al，Ga，Fe，In)快。对于储热密度，Y2(SO4)3·xH2O是最有希望的，因为在反应过程中质量变化最大(>；10%无水基)。这比现有的候选CaSO4·0.5H2O(6.6质量%无水基)的值要大。三方相RE2(SO4)3(RE=Yb，Y，Dy)插入水生成RE2(SO4)3·H2O的反应温度随RE3+离子半径的增大而升高。由于在β-RE_2(SO_4)_3·xH_2O、RE(OH)_3和REPO_4·xH_2O中也观察到了这种关系，这一经验知识应该有助于预测稀土化合物的脱水/水化反应温度。
To identify potential low-temperature thermochemical heat storage (TCHS) materials, hydration/dehydration reactions of M2(SO4)3 (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) are investigated by thermogravimetry (TG). These materials have the same rhombohedral crystal structure, and one of them, rhombohedral Y2(SO4)3, has been recently proposed as a promising material. All M2(SO4)3·xH2O hydrate/dehydrate reversibly between 30 and 200 °C at a relatively low pH2O (=0.02 atm). Among them, rare-earth (RE) sulfates RE2(SO4)3·xH2O (RE = Sc, Yb, Y, Dy) show narrower thermal hystereses (less than 50 °C), indicating that they have faster reaction rates than the other sulfates M2(SO4)3·xH2O (M = Al, Ga, Fe, In). As for the heat storage density, Y2(SO4)3·xH2O is most promising due to the largest mass change (>10 mass % anhydrous basis) during the reactions. This is larger than that of the existing candidate CaSO4·0.5H2O (6.6 mass % anhydrous basis). Regarding the reaction temperature of the water insertion into rhombohedral RE2(SO4)3 (RE = Yb, Y, Dy) to form RE2(SO4)3·H2O, it increases as the ionic radius of RE3+ becomes larger. Since such a relationship is also observed in β-RE2(SO4)3·xH2O, RE(OH)3, and REPO4·xH2O, this empirical knowledge should be useful to expect the dehydration/hydration reaction temperatures of the RE compounds.