A stable-performance ortho-to para-hydrogen conversion catalyst MIL-Br@MS

Abstract To enable long-term cryogenic storage of liquid hydrogen, the development of advanced catalytic systems for efficient o- to p-H 2 conversion during liquefaction processes has become imperative. This study presents the rational design of molecular sieve-supported catalysts (MIL@MS and MIL-Br@MS) through solvothermal synthesis, with particular emphasis on Br-induced magnetic regulation for catalytic performance. The results show that compared with MIL@MS, MIL-Br@MS had a high specific surface area, small pores, and a disordered magnetic field, which effects collectively contribute to increased adsorption potential and abundant active sites for nuclear spin conversion. MIL-Br@MS demonstrates superior catalytic activity with para-H 2 peak area reaching 54.2 μV·min –1 (100 mL min –1 ,). This work provides new insights into designing magnetic catalysts through halogen-induced electronic modulation, advancing the development of efficient hydrogen liquefaction systems.