Inelastic Neutron Scattering to probe H/D exchange in Zeolitic Imidazolate Frameworks for hydrogen isotope separations

Separating hydrogen and deuterium isotopes is presently among the most formidable separation challenges, due to their similar size, boiling point, and properties. Despite this there is a growing demand for deuterium, due to its use for isotope specific experiments and labelling studies in chemistry, biology, materials science, nuclear fusion, and medicine.[1] Current technologies to separate hydrogen (1H) and deuterium (2H), either require incredibly low temperatures (~30 K), have low D2/H2 separation efficiencies, or very low uptake capacities, making them inefficient. One approach is to employ materials that can exchange hydrogen and deuterium atoms. Metal organic frameworks (MOFs) are of particular interest for this, as they have higher concentrations of H atoms than other porous systems (e.g., zeolites or mesoporous silicas), whilst having an incredibly high surface area (> 1500 m2 g-1), increasing the interactions between the framework host and any gaseous species.[1] Recently using a combination of 1H and 2H solid state magic-angle spinning NMR (ssNMR), we have shown that the MOF Zn-ZIF-8, has potential in exchanging, and storing hydrogen and deuterium. In this experiment we will compare the INS spectra of hydrogenated Zn-ZIF-8, and fully deuterated Zn-ZIF-8, with our Zn-ZIF-8 sample after H/D exchange, allowing us to quantify the H/D exchange, and determine where this exchange occurs.