Maximizing the Density of π‐Electron in Metal‐Organic Frameworks for Benchmark Paraffin Separation

Abstract Selective paraffin adsorption is crucial in chemical processes but faces significant challenges. Herein a promising strategy by maximizing the density of π‐electron (D π is defined to be Number (π‐electron) /Volume (single pore) ) of metal‐organic framewok (MOF) pore is proposed to boost paraffin separation. SNNU‐126 features a triangular prismatic pore with the highest D π value of 0.2070 e Å −3 is selected and rationally regulated by incorporating amino electron‐donating groups (EDGs) to demonstrate the feasibility of this strategy. As expected, extraordinary D π value together with multiple EDGs endow SNNU‐126‐129 with top‐level adsorption capacity, exceptional IAST selectivity, excellent separation ability as well as highest productivity. Specially, SNNU‐129 with nine EDGs demonstrates the longest breakthrough interval times for C 2 H 6 /CH 4 (205 min g −1 ) and C 3 H 8 /CH 4 (710 min g −1 ) from the ternary gas mixture with one‐step CH 4 productivity of 15.56 mmol g −1 (purity > 99.5%) at 298 K and 1 bar, which surpass the values of all current adsorbents and set a benchmark for paraffin separation. In situ infrared spectra and DFT simulations clearly verify that maximizing the D π of MOF pore effectively enlarges the C─H···π interactions, widens the affinity gap, and results in extraordinary separation performance.