Synthetic strategies for the enhancement of Mg(OH)2 thermochemical performances as heat storage material

This work deals with the study of influence of multi walled carbon nanotubes (CNTs) characteristics on thermochemical performance of hybrid materials based on Mg(OH)2 (M) as heat storage medium. Two different functionalized CNTs samples are investigated, separated curly tubes (SN) and bundles of straight nanotubes (BN). Hybrids were synthesized by reverse deposition precipitation method and their structure was characterized by X-ray analysis and scanning electron microscopy. The heat storage performance was studied through a thermogravimetric apparatus, simulating heat storage/release cycles. It is demonstrated that separated CNTs owning mainly carboxylic groups increase the interaction with precipitated magnesium hydroxide, improving the reacted fraction during dehydration/hydration cycle. In terms of dehydration/hydration conversion the samples’ rank is SN- M>Mg(OH)2>BN-M. SN-M exhibits higher heat storage/output capacity (~1250 kJ/kgMg(OH)2, ~350 MJ/m3).