Hydrogen isotope separation in “trapdoor” chabazite as measured by a novel sonic gas sensor

Clean energy from nuclear fusion will require efficient technologies for hydrogen isotope separation. Separation by adsorption has shown high isotope selectivity, but only at impracticably low temperatures (<100 K). In this paper, the D 2 /H 2 hydrogen isotope selectivity of ‘trapdoor’ chabazite is measured for the first time and compared to zeolite 5A, zeolite 3A, HKUST-1 and MOF-74(Ni). H 2 and D 2 isotherms for potassium chabazite show that between 143 and 195 K, H 2 adsorption is selectively blocked leading to high ideal isotope selectivity (D 2 /H 2 = 1.83 at 143 K). Adsorption hysteresis is measured for the first time in trapdoor chabazite and zeolite 3A at similar temperatures which indicates trapdoor behaviour. An innovative breakthrough setup is developed including a whistle gas density sensor for deuterium detection. The D 2 /H 2 separation factor of Na–K chabazite from frontal breakthrough is 2.71 at 159 K, which is much higher than for zeolite 5A at 1.25 at 159 K and 1.7 at 77 K. • Trapdoor K-chabazite blocks H 2 adsorption between 143 and 195 K but not D 2 . • H 2 and D 2 isotherms of K-CHA, zeolite 3A and 5A, MOF-74(Ni) and HKUST-1. • Bespoke whistle sensor for real-time isotopic measurements. • Breakthrough experiments show D 2 /H 2 selectivity of 2.71 for trapdoor CHA at 159 K.