Kinetic separation of hydrogen isotopes over lignin-rich biomass-derived carbon molecular sieves
Deuterium (D2) is indispensable for isotope tracing, neutron scattering, and fusion reactions, yet its separation from hydrogen (H2) remains challenging due to their nearly identical physicochemical properties. Adsorptive separation exploiting the kinetic quantum sieving (KQS) effect at cryogenic temperatures offers a promising route, but demands precise pore engineering. Here, we report a biomass-derived carbon molecular sieve that permits rapid D2 transport while imposing a significant diffusion barrier for H2, enabling effective separation from D2/H2 mixtures. The molecular sieving micropores are generated by transforming cellulose components into slit-type carbon micropores, with lignin acting as a pore-size modifier. At 77 K, the diffusion rate of D2 is 1.8 times that of H2, leading to a D2 concentration in the recovered gas approximately 10% higher than that achieved with conventional microporous carbons. Aspen adsorption simulations demonstrate that D2 can be enriched to 90.1% from a 1.0% D2/H2 mixture within 12 successive cycles following a two-bed cryogenic pressure swing adsorption process. These findings advance the development of effective adsorbents for kinetic D2/H2 separation, offering a sustainable, low-cost route to deuterium enrichment.