Discovery of Catalysts That Prevent Boil-Off Losses in Liquid Hydrogen Production

Hydrogen, a promising source of next-generation clean energy, needs to be liquefied at a cryogenic temperature of −253°C or lower in order to be stored and transported efficiently. Meanwhile, there are two types of hydrogen molecules with different nuclei spin directions: ortho hydrogen and para hydrogen (Figure). The ortho-para ratio in room-temperature hydrogen gas is 3:1, whereas at a liquid hydrogen temperature, hydrogen is stable when almost 100% is in the para form. However, if hydrogen is rapidly liquefied, the conversion from ortho hydrogen to para hydrogen is delayed, and a substantial quantity of unstable ortho hydrogen will remain in the liquid. This residual ortho hydrogen continues to be converted during storage, causes energy release and partial vaporization of liquid hydrogen, and results in substantial loss (the red broken line in Figure). In order to prevent the loss, a high-performance catalyst that converts ortho hydrogen to para hydrogen before liquefaction (the blue broken line in Figure) is needed. However, conventional catalysts using magnetism, such as iron oxide, were insufficient in performance.

The research team proposed an original hypothesis that ortho-para hydrogen conversion is promoted, not by conventional magnetism, but by an inhomogeneous electric field (uneven static electricity) generated by the cation/anion arrangement on the surface of an oxide catalyst. Based on this hypothesis, the team succeeded in developing high-performance catalysts that surpass conventional catalysts, by combining low-cost oxide like silica (SiO₂) and alumina (Al₂O₃) with common metallic nanoparticles, such as iron (Fe) and cobalt (Co).

Liquid hydrogen plays a particularly important role in long-distance maritime transportation between hydrogen producing/exporting countries, such as Australia and the Middle East, and hydrogen importing countries, such as Japan. The catalysis design approach and high-performance catalysts discovered in this research are expected to contribute to the development of a hydrogen economy in Japan.

• This project was conducted by a research team consisting of Hideo Hosono (Team Leader, ElectroActive Materials Team, Research Center for Materials Nanoarchitectonics (MANA), NIMS [also Honorary Professor, Institute of Science Tokyo]) and Hideki Abe (Group Leader, Hydrogen Production Catalyst Materials Group, Research Center for Energy and Environmental Materials (GREEN), NIMS) as well as Takeshi Fujita (Professor, Kochi University of Technology). The work was supported by JST-Mirai program JPMJMI18A3.
• This research result was published online in The Journal of Physical Chemistry Letters on March 12, 2026.