Refining Pore Polarity in Metal–Organic Frameworks for Efficient Olefin Separation from MTO Products

High Resolution Image Download MS PowerPoint Slide The advancement of the methanol-to-olefins (MTO) process has intensified the urgent demand for the efficient separation of high-purity ethylene (C 2 H 4 ) and propylene (C 3 H 6 ) from MTO products, which remains a formidable challenge. Herein, we report three isostructural pillar-layered metal–organic frameworks with optimized pore environments by synergistically refining the methyl site density and pore sizes. Among them, the dimethyl-functionalized Ni-DMBDC exhibits superior olefin purification performances, delivering record ethane (C 2 H 6, 120.3 cm 3 g –1 at 1.0 bar) and C 3 H 6 (97.2 cm 3 g –1 at 0.1 bar) uptakes at 298 K. Moreover, it achieves high C 3 H 6 /C 2 H 4 (13.5) and C 2 H 6 /C 2 H 4 (1.8) selectivity, outperforming most reported MOF adsorbents. Dynamic breakthrough experiments confirm the exceptional separation sufficiency of Ni-DMBDC for C 3 H 6 /C 2 H 4 (50/50, v/v ) gas mixture even at a high flow rate of 10.0 mL min –1, yielding 124.2 and 76.8 L kg –1 of high-purity C 2 H 4 (99.9%) and C 3 H 6 (99.5%) in a single adsorption–desorption cycle, respectively. Notably, high-purity C 2 H 4 and C 3 H 6 (99.5%) can be simultaneously produced from a ternary C 2 H 4 /C 3 H 6 /C 2 H 6 mixture (50/20/7, v/v/v ) via this one-step process. Computational simulations further reveal that the synergistic effect of abundant methyl/phenyl groups and accessible O sites in Ni-DMBDC facilitates multiple guest–host interactions for efficient MTO product separation.