Hydrogen-bond-directed regulation of the stacking pattern in MOF adsorbents for efficient reversed C₃H₈/C₃H₆...

The adsorptive separation of propylene (C₃H₆) and propane (C₃H₈) is critically important in the petroleum industry. Nevertheless, the development of C₃H₈-selective metal-organic framework adsorbents is challenging, with only preferential C₃H₈ adsorption under low-pressure conditions. The non-uniform distribution of inert adsorption sites results in poor separation performance across a wide pressure range. Herein, we regulate the stacking pattern via hydrogen bonds of interlayers to construct uniform and parallel π-electron surfaces. As a result, the optimized Co-MOF-H-bond exhibits preferential C₃H₈ adsorption across the 0-1.0 bar range with a high C₃H₈ adsorption capacity of 2.03 mmol g^-1 at 298 K compared to Co-MOF-vdW (1.24 mmol g^-1). Moreover, the adsorption selectivity for C₃H₈/C₃H₆ increases from 0.9 to 2.6. Dynamic breakthrough experiments demonstrate that polymer-grade C₃H₆ (>99.9%) can be directly obtained with a productivity of 12.2 L kg^-1. Grand Canonical Monte Carlo simulations and density functional theory calculations reveal that the synergistic effect of uniform distribution of adsorption sites and superimposed van der Waals forces is responsible for the enhanced adsorption of C₃H₈.