Investigation of Ca12Al14O33 Mayenite for hydration/dehydration thermochemical energy storage

Abstract Thermal energy storage using a reversible chemical reaction is a key parameter for increasing the storage capacity especially for medium and high temperature applications. The reversible hydration/dehydration reaction of calcium hydroxide Ca(OH)2 to calcium oxide CaO is among the most investigated system due to its reaction cyclability and interesting operating temperature above 450 °C suitable for high temperature applications. However, the indicated reaction temperature was considered too high for some industrial applications which limit a further development of thermal energy storage technologies using this promising reaction system. In this regard, the material development is a key point to broaden the application of sustainable technologies. In this work, the investigation of Mayenite with general formula Ca12Al14O33 as a thermochemical energy storage material was conducted. Thereby, it was confirmed the possibility of the pair “Ca12Al14O12(OH)42”/Ca12Al14O33 to store and release the heat through chemical reaction thanks to a novel activation process of the pristine Mayenite that is presented for the first time in this work. This study might help to identify new pairs based on materials that have already been classified as inactive for the hydration/dehydration reaction. In addition, it was found that the hydration reaction temperature of “Ca12Al14O12(OH)42”/Ca12Al14O33 pair of 228 °C is much lower compared to that of CaO/Ca(OH).