Inelastic neutron spectroscopy to probe high pressure H2 adsorption in zeolites

Separating hydrogen and deuterium is among the most challenging separations in the chemical industry due to their similarities, often requiring energy intensive processes at 30 K to achieve meaningful separation. Therefore, alternative technologies that operate at higher temperatures are being explored to achieve both energy and cost savings. Recent studies have shown that zeolites, microporous frameworks (pores less than 2 nm), are able to differentiate hydrogen and deuterium, through a process known as quantum sieving. Purely siliceous (SiO2) chabazite (CHA) has poor D2/H2 selectivity. But replacing framework Si4+ species with Al3+, creates a charge imbalance, which is countered by extra-framework cations binding to the zeolite. To understand the hydrogen interactions, it is important to observe changes in the hydrogen rotor band. Originally, we attempted to observe this in our NaK/CHA system before and after the introduction of 0.95 Bars of hydrogen to mimic our uptake data. But, while this material can effectively separate hydrogen and deuterium, it has a very low hydrogen uptake, showing scarce few differences in the spectra. In an industrial separation process, hydrogen pressures would exceed 20 Bars, as such we wish to repeat this experiment, with 20 Bars of pressure, resulting in a tenfold hydrogen uptake, within our NaK/CHA system.