Fourier-transform infrared analysis of the dehydration mechanism of Mg(OH)2 and chemically modified Mg(OH)2

研究業績

水酸化マグネシウムの脱水反応におけるリチウム化合物添加効果に関する論文が公開されました.
R. Kurosawa, M. Takeuchi and J. Ryu, J. Phys. Chem. C, 125, 5559-5571 (2021).
小人さんがケーキのイチゴを掘り出しているイラストは,水酸化マグネシウム表面に存在するリチウム化合物が異なる役割を持つことを表現したものです.
Cover Artに応募しましたが,マンガっぽいのはNGということだったので,ここに載せておきます(苦笑)

Abstract
Mg(OH)2 is a medium-temperature chemical heat storage material. The addition of LiCl and/or LiOH to Mg(OH)2 has been reported to promote the dehydration of Mg(OH)2. However, the mechanism underlying the effect of the addition of Li compounds on the dehydration of Mg (OH)2 has not yet been elucidated. This study focused on the dehydration of pure Mg(OH)2 and Mg(OH)2 with added LiCl and/or LiOH. We analyzed the role of the Li compounds in the dehydration of Mg(OH)2 using X-ray diffraction and Fourier-transform infrared (FT-IR) spectroscopy. Our FT-IR measurements assigned the peaks of the bulk OH groups of Mg(OH)2, which are not referred to in previous studies. FT-IR measurements revealed that the surface state of Mg(OH)2 with added LiOH with a Mg(OH)2:LiOH mole rate of 100:20 was similar to that of MgO. This indicated that the addition of LiOH to Mg(OH)2 affected the dehydration of the Mg(OH)2 surface. Moreover, we confirmed that LiCl affected the dehydration of the bulk Mg(OH)2 phase. Using these results, we proposed possible mechanisms for the effects of the addition of LiCl and/or LiOH on the dehydration of Mg(OH)2. Lastly, we discuss the reason for the Li compounds promoting the dehydration of Mg(OH)2.

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