Optimizing supramolecular interactions within metal-organic frameworks for ultra-high purity propylene purification

Purifying ultra-high purity propylene (>99.995%) with an energy-efficient adsorptive separation method is a promising yet challenging technology that remains unfulfilled. Instead of solely considering the effect of adsorbents on guest molecules, we propose a synergistic adsorption mechanism for the deep removal of propane and propyne, utilizing supramolecular interactions in both "host-guest" and "guest-guest" systems. Through modulation of the pore environment, Ni-DMOF-DM exhibits exceptionally high adsorption capacities for propane and propyne (171 and 197 cm(3)/g at ambient temperature and pressure, respectively), and unprecedented propane/propylene separation selectivity (2.74). Theoretical calculations confirm the geometric interactions of C-H<middle dot><middle dot><middle dot>pi bonds and C-H<middle dot><middle dot><middle dot>O hydrogen bonds resulting from host-guest interactions, alongside C-H<middle dot><middle dot><middle dot>H guest-guest interactions within the confined pore space. Breakthrough experiments demonstrated that ultra-high purity propylene (propane < 0.005% and propyne < 1.0 ppm) can be directly collected from ternary mixtures on Ni-DMOF-DM, achieving a productivity of up to 152.14 L/kg.