Catalysts that prevent boil-off losses in liquid hydrogen production hold promise for a hydrogen-energy society

Catalysts that prevent boil-off losses in liquid hydrogen production hold promise for a hydrogen-energy society Stephanie Baum Scientific Editor Andrew Zinin Lead Editor A joint research team has discovered high-performance catalysts capable of significantly reducing "boil-off losses," which had been a longstanding issue in liquid hydrogen storage and transportation. These composite catalysts, in which metallic nanoparticles, such as iron, are supported on silicon dioxide (silica) or other low-cost oxide, demonstrate significantly superior performance compared to conventional iron oxide-based catalysts. In this research, the team demonstrated a new mechanism where ortho to para hydrogen conversion is promoted, not by magnetism as in conventional mainstream mechanisms, but by an inhomogeneous electric field on the surface of the catalyst. This research result, which is expected to contribute to a hydrogen-energy society, is published in The Journal of Physical Chemistry Letters. The team included researchers from NIMS, the Institute of Science Tokyo, and Kochi University of Technology. Hydrogen, a promising source of next-generation clean energy, must 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. 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. In order to prevent the loss, a high-performance catalyst that converts ortho hydrogen to para hydrogen before liquefaction is needed. However, conventional catalysts using magnetism, such as iron oxide, have been 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. Publication details Hiroshi Mizoguchi et al, Exploring Ortho–Para Hydrogen Conversion Catalysts Based on Surface Electric Field Gradient, The Journal of Physical Chemistry Letters (2026). DOI: 10.1021/acs.jpclett.6c00357 Journal information: Journal of Physical Chemistry Letters Provided by National Institute for Materials Science