Ultra-Efficient Ortho-Para Hydrogen Conversion by Ni-MOF-74

Forbidden interexchange between molecular hydrogen's nuclear spin isomers, namely, ortho-hydrogen and para-hydrogen, is drastically accelerated with matal-organic framework (MOF) of Ni-MOF-74.While the highly porous, open-metal-site-rich material reportedly shows promising ortho-para conversion efficiency (Polyukhov et al., ACS Energy Letters 7 (2022) 4336), we further unlock the power of Ni-MOF-74 by eliminating alumina medium used abundantly so far, also removing impurities, and thereby optimizing the chance for the hydrogen molecules to encounter the nickel open metal sites as they pass through the column packed with the ortho-para conversion accelerating material.With 1 H nuclear magnetic resonance studies, we reveal a soared ortho-para conversion efficiency up to 400 s -1 , up two orders of magnitude compared to the current-best materials.