Quantum sieving effect of three-dimensional Cu-based organic framework for H2 and D2

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable nanoporous structures for gas adsorption and separation.
• Understanding quantum effects in gas adsorption is crucial for developing advanced separation technologies.

Purpose of the Study:

• To investigate the quantum molecular sieving effect for hydrogen (H 2) and deuterium (D 2) adsorption in a copper-based MOF (CuBOTf).
• To determine the influence of temperature and pore structure on gas adsorption selectivity and hysteresis.

Main Methods:

• Synchrotron X-ray powder diffraction for crystal structure determination.
• Nitrogen adsorption for effective nanoporosity measurement.
• Experimental H 2 and D 2 adsorption isotherm measurements at 40 K and 77 K.
• Grand Canonical Monte Carlo (GCMC) simulations and quantum simulations using Feynman-Hibbs effective potential.

Main Results:

• Experimental and quantum simulations confirmed the quantum molecular sieving effect for H 2 and D 2 adsorption on CuBOTf at 77 K, with a selectivity of 1.2 for a mixed gas.
• Adsorption hysteresis due to pore blocking was observed at 40 K, with higher selectivity for D 2 over H 2 (2.6–5.8).
• Quantum molecular sieving was also suggested for a 3D MOF structure at 77 K.

Conclusions:

• CuBOTf exhibits quantum molecular sieving behavior for H 2 and D 2 adsorption.
• Temperature-dependent pore blocking effects significantly impact gas selectivity.
• MOFs show promise for selective hydrogen isotope separation via quantum sieving.