doi: 10.3850/978-981-08-7614-2_IMPRES017


Dehydration and Hydration Behavior of LiCl-modified Mg(OH)2 as a Material for Chemical Heat Pumps


Hirokazu Ishitobi1, Yoshitomo Sato1, Keirei Uruma2, Junichi Ryu2,a and Yukitaka Kato2

1Department of Nuclear Engineering, Tokyo Institute of Technology, 2-12-1-N1-22, Ookayama, Meguro-ku, Tokyo 152-8550, Japan

2Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-22, Ookayama, Meguro-ku, Tokyo 152-8550, Japan.

acyliu@nr.titech.ac.jp

ABSTRACT

Lithium chloride (LiCl)-modified magnesium hydroxide (Mg(OH)2) is potentially a new material for chemical heat pumps, but there is insufficient information for its dehydration and hydration behaviors. In this study, dehydration and hydration reactions (corresponding to the heat storage operation and the heat output operation) of authentic Mg(OH)2 and LiCl-modified Mg(OH)2 were investigated by using thermogravimetric methods and near infrared spectroscopy. The dehydration of authentic Mg(OH)2 proceeded as a one-step reaction, but dehydration of LiCl-modified Mg(OH)2 was a two-step reaction. The activation energy for dehydration of Mg(OH)2 was lowered by LiCl modification. The mechanism of hydration for magnesium oxide (MgO) was different to that for hydration of LiCl-modified MgO. This difference was explained by the contribution of LiCl on the MgO particle surface.

Keywords: Chemical heat pump, Dehydration reaction, Hydration reaction, Gas-solid reaction.


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