Room-temperature chromatographic H2/D2 separation via a solid dihydrogen complex with balanced thermodynamics and kinetics

Abstract

To meet the growing demand for hydrogen isotopes, the development of efficient and practical methods for isotope separation 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°| values of materials have prevented effective separation under ambient conditions. In addition, designing materials with a high |ΔΔH°| value is challenging. Herein, we report the largest |ΔΔH°| value of 5.0 kJ mol⁻¹ observed in the solid-state dihydrogen complex [Mn(PCy₃)₂(CO)₃][BARF], exceeding that of all previously known materials. Quantum chemical calculations and statistical analyses were employed to elucidate the origin of this separation ability. Furthermore, we demonstrated H₂/D₂ separation at ambient temperature using gas chromatography. This work presents a novel strategy to enhance the efficiency of isotope separation, thereby enabling H₂/D₂ separation at room temperature.