Addressing safety risks and energy loss for a society with hydrogen energy
A research group led by Professor Hiroyuki Nishide and Professor Kenichi Oyaizu from the Department of Applied Chemistry developed a hydrogen-carrying polymer, which can be molded as a tangible, safe, and compact plastic sheet.
Although technology developments and research on realizing hydrogen as a major energy source have gone under way, the conventional methods of storing and carrying hydrogen were accompanied by safety risks such as explosions. Hence, hydrogen-exposed organic compounds have been recently studied as hydrogen storage materials, for their ability to stably and reversibly store hydrogen by forming chemical bonds. However, these compounds require vessels or sealed tanks operated at high pressure and/or temperature and often encounter difficulty in their separation from the evolved hydrogen gas. A much safer and more efficient system for storing and storing and carrying hydrogen has been in demand.
The research group discovered that ketone (fluorenone) polymer, which can be molded as a plastic sheet, can fix hydrogen via a simple electrolytic hydrogenation at -1.5V (versus Ag/AgCl) in water at room temperature. On the other hand, fluorenol polymer, a hydrogenated alcohol derivative of fluorenone, can release hydrogen when heated at 80 degree Celsius with an aqueous iridium catalyst. What’s more, the group proved that the cycle of repeatedly fixing and releasing hydrogen under mild conditions without significant deterioration, leading to the developement of a portable, plastic ketone polymer with hydrogen that can be carried around in your pocket.
The advantages of the ketone/alcohol polymer include easy handling, moldability, robustness, non-flammability and low toxicity, and the research results are expected to make contributions in building distributed energy systems in regional areas.
Hydrogen is often described as the fuel of the future, particularly when applied to hydrogen-powered fuel cell vehicles. One of the main obstacles facing this technology – a potential solution to future sustainable transport – has been the lack of a lightweight, safe on-board hydrogen storage material.
A major new discovery by scientists at the universities of Oxford, Cambridge and Cardiff in the UK, and the King Abdulaziz City for Science and Technology (KACST) in Saudi Arabia, has shown that hydrocarbon wax rapidly releases large amounts of hydrogen when activated with catalysts and microwaves.
This discovery of a potential safe storage method, reported in the Nature journal Scientific Reports, could pave the way for widespread adoption of hydrogen-fuelled cars.
Study co-author Professor Peter Edwards, who leads the KACST-Oxford Petrochemical Research Centre (KOPRC), a KACST Centre of Excellence in Petrochemicals at Oxford University, said: ‘This discovery of a safe, efficient hydrogen storage and production material can open the door to the large-scale application of fuel cells in vehicles.’
Co-author Dr Tiancun Xiao, a senior research fellow at Oxford University, said: ‘Our discovery – that hydrogen can be easily and instantly extracted from wax, a benign material that can be manufactured from sustainable processes – is a major step forward. Wax will not catch fire or contaminate the environment. It is also safe for drivers and passengers.’
Co-author Professor Hamid Al-Megren, from the Materials Research Institute at KACST, said: ‘This is an exciting development – it will allow society to utilise fossil fuels or renewable-derived wax to generate on-board hydrogen for fuel cell applications without releasing any carbon dioxide into the air.’
Hydrocarbons are natural, hydrogen-rich resources with well-established infrastructures. The research team has developed highly selective catalysts with the assistance of microwave irradiation, which can extract hydrogen from hydrocarbons instantly through a non-oxidative dehydrogenation process. This will help unlock the longstanding bottleneck hindering the widespread adoption of hydrogen fuel technology.
Co-author Professor Angus Kirkland, from the Department of Materials at Oxford University and Science Director at the new electron Physical Science Imaging Centre (ePSIC) at Harwell Science and Innovation Campus, described the breakthrough as an exemplar of how Oxford is able to respond to key academic and industrial problems by using interdisciplinary resources and expertise.
Co-author Professor Sir John Meurig Thomas, from the Department of Materials Science and Metallurgy at the University of Cambridge, said the work could be extended so that many of the liquid components of refined petroleum and inexpensive solid catalysts can pave the way for the generation of massive quantities of high-purity hydrogen for other commercial uses, including CO2-free energy production.
Professor Edwards added: ‘Instead of burning fossil fuels, leading to CO2, we use them to generate hydrogen, which with fuel cells produces electric power and pure water. This is the future – transportation without CO2 and hot air.’
Engineers at the University of California, San Diego, have created new ceramic materials that could be used to store hydrogen safely and efficiently.
The researchers have created for the first time compounds made from mixtures of calcium hexaboride, strontium and barium hexaboride. They also have demonstrated that the compounds could be manufactured using a simple, low-cost manufacturing method known as combustion synthesis.
The work is at the proof of concept stage and is part of a $1.2 million project funded by the National Science Foundation, a collaboration between UC San Diego, Alfred University in upstate New York and the University of Nevada, Reno. The manufacturing process for the ceramics is faster and simpler than traditional methods used to manufacture these types of materials. The researchers presented their work in March 2014 at the third International Symposium on Nanoscience and Nanomaterials in Mexico.