A scalable ultramicroporous metal-organic framework for highly effective propylene/propane separation at elevated temperatures

The separation of propylene (C3H6) and propane (C3H8) presents a significant industrial challenge due to their similar molecular dimensions and physicochemical properties. Among various separation methods, molecular sieving emerges as the most promising approach, but it will be significantly compromised at high temperatures due to the significant thermal motion. Here, we report a thermally robust zinc-based metal-organic framework (MOF) that can be synthesized on sub-kilogram scale and achieve exceptional C3H6/C3H8 separation performances across a broad temperature range (298–353 K). Unlike conventional MOFs suffering from thermal lattice expansion to give poorer selectivity, this new MOF gives the adsorption capacity of C3H6 essentially unchanged and that of C3H8 negligible at elevated temperatures, outperforming most state-of-the-art adsorbents, in virtue of multiple hydrogen bonds at the aperture. Column breakthrough experiments confirmed the excellent separation capability, and showed no performance degradation over multi-round adsorption-desorption cycles at 353 K. This study addresses the critical challenge of the trade-off between temperature and selectivity in adsorptive separation, which offers new insights into the design of porous structures for highly effective separation at high temperatures.