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 C₂H₆/CH₄ (205 min g⁻¹) and C₃H₈/CH₄ (710 min g⁻¹) from the ternary gas mixture with one‐step CH₄ 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.