From Coal Ashes to Solid Sorbents for Hydrogen Storage

The purpose of this work is the literature review in the field of hydrogen storage in solid sorbents. The best solid sorbents for hydrogen storage were selected with the possibility of synthesis them from coal fly ash. In addition, the on-board hydrogen storage analysis was carried out. The review method consists of two parts. The first part based on research questions included types of the best sorbents for hydrogen storage, the possibility to obtain them from coal fly ash and practical use in hydrogen storage system on-board. The second part was the selection of publications from The Web of Science and Elsevier Scopus databases and the analysis as well as available reports on the websites at this scope. After searching the relevant articles in the databases, abstracts were analysed in terms of the questions asked. The links between references and research were checked. The search procedure was repeated several times. Finally, articles with high Impact Factor index published by authors recognized on a global scale were selected for the presented review. The collected information proved that carbon materials are suited to hydrogen storage because of their high porosity, large specific surface area and thermal stability. Besides, solid sorbents such as zeolites, metal-organic frameworks, activated carbons or zeolite template carbons can be obtained from coal fly ash. Thanks to silicon, aluminium and unburned carbon content fly ash is a good material for the synthesis of hydrogen sorbents. Under cryogenic conditions and high pressure, it is possible to adsorb as much as 8.5 wt% of hydrogen. Although the Department of Energy (DOE) requirements for the hydrogen storage system on-board vehicles are not met, the review of scientific publications shows that research in this area is developing and better parameters are being obtained.