Structure and hydration state characterizations of MgSO4-zeolite 13x composite materials for long-term thermochemical heat storage

Abstract

Salt hydrate based composite materials are promising to be used for long-term thermochemical heat storage. MgSO4-Zeolite 13x composite materials were prepared in the present work using the solution impregnation method to reveal detailed characteristics of salt hydrates-zeolite composite materials. The porous structure of the composite materials with different MgSO4 contents was characterized, and the adsorption ability and hydration state of MgSO4 of the composite materials under different relative humidities (RH) were investigated. The results show, although the porous surface area and the pore volume were reduced after the penetration of the MgSO4 salt, the water adsorption ability can still be increased. The water adsorption ability also depended highly on the RH. Besides, not all the MgSO4 formed the hydrate state of MgSO4·6H2O and no MgSO4·7H2O were detected even for the equilibrium adsorption at high RH of 80%. The composite with 8 wt% MgSO4 showed the best performance, and could be a promising thermochemical material for long-term heat storage.