Chemists developed a liquid storage material for hydrogen

Aside developing more efficient methods in hydrogen production, researchers around the world are developing ways to store hydrogen for subsequent use. University of Oregon (UO) chemists developed a boron-nitrogen-based liquid-phase storage material for hydrogen which is more suitable than currently known ways to store hydrogen because it can perform safely at room temperature and is both air- and moisture-stable.

Most of the methods devised to store hydrogen as a compact energy carrier for mobile applications have major flaws that keep them away from commercial use. For example, storage of liquid hydrogen and slush hydrogen (which is a combination of liquid and solid hydrogen) requires a well insulated cryogenic storage (which consumes a lot of energy to maintain temperatures close to absolute zero) and compressed hydrogen has a large volume and it requires large tanks for storage.

“In addition to renewable hydrogen production, the development of hydrogen storage technologies continues to be an important task toward establishing a hydrogen-based energy infrastructure”, said Shih-Yuan Liu, professor of chemistry and researcher in the UO Material Sciences Institute.

The new UO approach differs from many other technologies because it liquid-based rather than solid, and researchers envision it as a potential instrument in transition from a gasoline to a hydrogen infrastructure.

“The field of materials-based hydrogen storage has been dominated by the study of solid-phase materials such as metal hydrides, sorbent materials and ammonia borane”, said Liu. “The availability of a liquid-phase hydrogen storage material could represent a practical hydrogen storage option for mobile and carrier applications that takes advantage of the currently prevalent liquid-based fuel infrastructure.”

Ironically, Liu’s team started with a solid material – a six-membered cyclic amine borane – that readily trimerizes (form a larger desired molecule) with the release of hydrogen. Reducing the ring size from a 6- to a 5-membered ring, the group succeeded in creating a cyclic amine borane-based platform called BN-methylcyclopentane – a liquid version that has low vapor pressures and does not change its liquid property upon hydrogen release.

In addition to its temperature and stability properties, it also features clean, fast and controllable hydrogen desorption which occurs without any phase change. It uses readily available iron chloride as a catalyst for desorption, and allows recycling of spent fuel into a charged state. However, the researchers cautioned that the technology still needs to increase hydrogen yield and develop a more energy efficient regeneration mechanism.

For more information, read the paper published in the Journal of the American Chemical Society named: “A Single-Component Liquid-Phase Hydrogen Storage Material”.