Magneto-chemistry of catalysts for liquid hydrogen production and storage

A body of accumulated knowledge on the magneto-chemistry of catalysts for the hydrogen ortho-para conversion is reviewed in order to bridge the gap between theoretical work, laboratory experiments and current industrial needs. Some key issues raised by the conversion of hydrogen nuclear spin isomers, such as its magnetic patterns, which are only partially resolved, are first summarized and the industrial challenges currently faced regarding hydrogen liquefaction and storage are discussed. The theoretical analysis required to understand the quantum characteristics of hydrogen molecules begins with the thermodynamic properties of non-equilibrium mixtures of their two varieties, ortho and para. This is followed by a description of the various electro-magnetic catalytic channels linked to the specific properties of the catalysts, and a study of the energy and momenta exchanges between the catalysts and hydrogen gas. The third section is devoted to the magnetochemistry of catalysts, their morphologies, surfaces and porous structures, their ability to diffuse or adsorb a flow of hydrogen, and measurements of catalytic rates, with particular emphasis on "in situ" and "site-specific" experimental methods. The fourth section presents current industrial challenges, highlighting the importance of catalytic steps, and their modeling, in hydrogen liquefaction and storage. The irreversible nature of hydrogen flow through porous catalysts in liquefiers is discussed, and an original short-term hydrogen reservoir model is presented. It is based on the cryogenic, cybernetic, hydrodynamic and catalytic properties of a barrage system of successive microporous catalysts. Finally, break-even times for storage processes are introduced and discussed.