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 C 2 H 2 from C 2 H 4 is crucial for producing polymer-grade C 2 H 4, yet it presents a significant challenge due to their similar physicochemical properties. Conventional carbon materials typically show preferential C 2 H 4 adsorption and poor C 2 H 2 uptake, particularly under low-pressure conditions. Herein, we demonstrate π-conjugated C 2 N-type carbon materials (CHAT- x ) as high-performance adsorbents for removing trace C 2 H 2 impurities from bulk C 2 H 4 . 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 C 2 H 2 uptake of 19.7 cm 3 /g at 298 K and 0.01 bar among carbon materials, coupled with excellent C 2 H 2 /C 2 H 4 separation selectivity of 4.5. Breakthrough experiments demonstrate the clear separation of a C 2 H 2 /C 2 H 4 (1/99, v/v) mixture dynamically, enabling the production of C 2 H 4 with a purity exceeding 99.9% in a single adsorption process. Theoretical calculations reveal that the high C 2 H 2 capacity and separation selectivity arise from the polar pore channels, enriched with pyrazinic nitrogen atoms, which act as enthalpically favored binding sites for C 2 H 2 molecules by stronger multibinding interactions. This work holds significant promise for developing C x N y -type carbon materials with a well-controlled pore interface, designed for systems requiring the deep removal of trace impurities.