Exploration of functional group effects on D2/H2 separation selectivity within the UiO-66 framework

Abstract

The efficient separation of deuterium from hydrogen remains a significant challenge due to the limitations of conventional techniques, such as cryogenic distillation and the Girdler-sulfide process combined with electrolysis, which are char-acterized by substantial energy demands and relatively low separation coefficients. In contrast, the quantum sieving effect, based on porous materials, offers a promising approach to overcoming these challenges. This study presents a novel application of strong adsorption sites (μ3-OH group) within the nanoporous metal-organic framework of UiO-66 for hydrogen isotope separation. By incorporating diverse organic functional groups into UiO-66, we successfully synthesized four derivative materials: UiO-66-NH2, UiO-66-CH3, UiO-66-NO2, and UiO-66-Ph. Experimental data reveal that the introduction of these functional groups modulated the material's pore size and channel polarity, significantly impacting its adsorption and separation performance for hydrogen isotopes. Notably, UiO-66-NH2, with the smallest pore size and highest channel polarity, exhibited superior hydrogen isotope adsorption capacity and selectivity, highlighting its potential as an effective adsorbent for isotope separation.