Tailored Postsynthetic Nitration of a Hypercrosslinked Polymer for Single‐Step Ethylene Purification from a Ternary C2 Gas Mixture

Abstract

AbstractPurifying C2H4 from a ternary C2H2/C2H4/C2H6 mixture poses a substantial industrial challenge due to their close physical and chemical properties. In this study, we introduce an innovative design approach to regulate and optimize the nitration degree of a hypercrosslinked polymer to achieve targeted separation performance. We synthesized a porous organic polymer (HCP) using the solvent knitting method and carried out its postsynthetic nitration, resulting in HCP‐NO2‐1 and HCP‐NO2‐2 with different nitration degrees. Notably, the adsorption capacity shifted from C2H6 > C2H4 ≈ C2H2 for HCP to C2H2 > C2H6 > C2H4 for HCP‐NO2‐1 and to C2H2 > C2H4 ≈ C2H6 for HCP‐NO2‐2, demonstrating the controllable nature of the separation process via the polar nitro group insertion. Remarkably, HCP‐NO2‐1 exhibited a desirable, selective separation of C2H4 from the C2H6/C2H4/C2H2 mixture thanks to an exquisite combination of the acidic proton‐polar nitro group and nonpolar C−H⋅⋅⋅π interactions. Separation capability was further corroborated by computational simulations and breakthrough tests. This work marks a significant advancement as the first successful postsynthetic functionalization strategy for C2H4 purification from a ternary gas mixture among porous organic polymers.