Room-Temperature Chromatographic H₂/D₂ Separation via Solid Dihydrogen Complex with Balanced Thermodynamics and Kinetics

Abstract

To meet the growing demand for hydrogen isotopes, the development of efficient and practical isotope separation techniques for dihydrogen is essential to replace the current cryogenic distillation method operating at 20 K. One of the most promising alternatives is chemical affinity quantum sieving (CAQS), which exploits differences in adsorption enthalpy (|ΔΔH°|) arising from variations in zero-point vibrational energy (ZPVE) between isotopologues. However, low |ΔΔH°| value of previous materials prevented effective separation under ambient conditions, and it is challenging to design the materials with high |ΔΔH°| value. Here, we report the largest |ΔΔH°| value of 5.0 kJ/mol observed in the solid-state dihydrogen complex [Mn(PCy3)2(CO)3][BARF], exceeding all previously known materials. Quantum chemical calculations and statistical analyses were employed to elucidate the origin of this separation ability. Furthermore, we successfully demonstrated H2/D2 separation at ambient temperature using a gas chromatography technique. This work presents a novel strategy to enhance isotope separation efficiency, enabling H2/D2 separation at room temperature.