Sorption composite materials for solar thermal energy storage

Two different composites, one with disordered mesoporous iron silicate matrix and the other with ordered mesoporous matrix together with calcium chloride, are presented. The introduction of CaCl2 in the matrices improves the maximal water sorption capacity. The composite with disordered mesoporous matrix showed a maximal water uptake of 0.58 g/g at 5.6 kPa, while the composite with ordered mesoporous matrix revealed higher maximal water uptake of 0.88 g/g. These composites show good hydrothermal stability after 20 cycles of sorption/desorption between temperatures of 150 °C and 40 °C and at water vapor pressure of 5.6 kPa. After the cycling test no leakage of the salt hydrate from the composites was detected.