Benchmark Paraffin Adsorption in a Super-Hydrophobic Porous Coordination Polymer with Blade-like Circular Phenyl Nanotraps

Abstract

Selective capture of paraffin from olefin that permits one-step purification of olefin is significantly important, yet developing adsorbents with high separation selectivity and hydrophobicity remains a daunting challenge. Although aromatic environments can enhance paraffin affinity and hydrophobicity through nonpolar interactions, water adsorption still occurs in regions distant from the aromatic rings, as well as in secondary pores that are always overlooked. Herein, we reported an ultramicroporous porous coordination polymer (ZnFPCP) featuring blade-like circular phenyl paraffin nanotraps. As further validated by DFTB calculations, GCMC simulations, and in situ FT-IR analysis, these ultramicroporous paraffin nanotraps created by surrounding benzene rings enhance the preferential adsorption of paraffin, and the segmented spaces between adjacent nanotraps in the blade-like structure combined with hydrophobic petal-like secondary pore channels enclosed by fluorinated functional groups further mitigates the water co-adsorption. Remarkably, ZnFPCP exhibited outstanding IAST selectivity of C3H8/C3H6 (2.08) and competitive selectivity of C2H6/C2H4 (2.93) under ambient conditions, while also exhibiting record-breaking C3H8 and C2H6 uptake at low pressures. Breakthrough experiments demonstrated the excellent performance of ZnFPCP in olefin purification, affording the exceptional productivity of ultra-high purity (99.99%) for C3H6 and C2H4. Robust stability and super hydrophobicity highlight its potential in harsh industrial application scenarios.