Dynamic Studies on Kinetic H2/D2 Quantum Sieving in a Narrow Pore Metal–Organic Framework Grown on a Sensor Chip

The separation of deuterium from hydrogen still remains a challenging and industrially relevant task. Compared to traditional cryogenic methods for separation, based on different boiling points of H and D, the use of ultramicroporous materials offers a more efficient alternative method. Due to their rigid structures, permanently high porosity, tunable pore sizes and adjustable internal surface properties, metal–organic frameworks (MOFs), a class of porous materials built through the coordination between organic linkers and metal ions/clusters, are more suitable for this approach than zeolites or carbon-based materials. Herein, dynamic gas flow studies on H/D quantum sieving in MFU-4, a metal-organic framework with ultra-narrow pores of 2.5 Å, are presented. A specially designed sensor with a very fast response based on surface acoustic waves is used. On-chip measurements of diffusion rates in the temperature range 27–207 K reveal a quantum sieving effect, with D diffusing faster than H below 64 K and the opposite selectivity above this temperature. The experimental results obtained are confirmed by molecular dynamic simulation regarding quantum sieving of H and D on MOFs for which a flexible framework approach was used for the first time.D.V. and A.W. are grateful for financial support by DFG: priority program 1928 “Coordination Networks: Building Blocks for Functional Systems”. This work was supported in part by the Cluster of Excellence NIM (Nanosystems Initiative Munich) of the German Government. B.P. gratefully acknowledges financial support by the Bavarian Science Foundation. G.S. thanks MINECO of Spain for funding (SEV‐2016‐0683 and MAT2015‐71842‐P) and ASIC‐UPV for the use of computational facilities