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

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.