Manipulation of Pore Interface of π-Conjugated Carbon Networks for Benchmark C ₂ H ₂ /C ₂ H ₄ Adsorptive Separation

The deep removal of trace C2H2 from C2H4 is crucial for producing polymer-grade C2H4, yet it presents a significant challenge due to their similar physicochemical properties. Conventional carbon materials typically show preferential C2H4 adsorption and poor C2H2 uptake, particularly under low-pressure conditions. Herein, we demonstrate π-conjugated C2N-type carbon materials (CHAT-x) as high-performance adsorbents for removing trace C2H2 impurities from bulk C2H4. Specifically, CHAT-600 features an ultrahigh nitrogen content (30.7 atom %) and well-defined micropores centered at 0.7 nm. Benefiting from the unique pore interface, CHAT-600 performs a record-high C2H2 uptake of 19.7 cm3/g at 298 K and 0.01 bar among carbon materials, coupled with excellent C2H2/C2H4 separation selectivity of 4.5. Breakthrough experiments demonstrate the clear separation of a C2H2/C2H4 (1/99, v/v) mixture dynamically, enabling the production of C2H4 with a purity exceeding 99.9% in a single adsorption process. Theoretical calculations reveal that the high C2H2 capacity and separation selectivity arise from the polar pore channels, enriched with pyrazinic nitrogen atoms, which act as enthalpically favored binding sites for C2H2 molecules by stronger multibinding interactions. This work holds significant promise for developing CxNy-type carbon materials with a well-controlled pore interface, designed for systems requiring the deep removal of trace impurities.