Precision Cross‐Section Sieving via a Deterministic‐Lateral‐Displacement‐Inspired Metal–Organic Framework for Simultaneous Separation of C4 Olefin and Paraffin Isomers

ABSTRACT The simultaneous separation of n/iso‐C ₄ H ₈ and n/iso‐C ₄ H ₁₀ mixtures presents a significant challenge due to the minimal difference in kinetic diameters (Δ < 0.2 Å) between n‐butane and iso‐butene. Inspired by the passive sorting mechanism of droplets via deterministic lateral displacement (DLD) in microfluidic architectures, we designed and synthesized a zinc‐based metal–organic framework (CALF‐20) featuring a canonical DLD array‐like structure, wherein Zn' serves as periodic micropillar‐like structural motifs. CALF‐20 exhibits a critical pore cross‐section precisely tailored to lie between the minimum cross‐sectional areas of iso‐C ₄ H ₈ and n‐C ₄ H ₁₀ , enabling simultaneous specific recognition of n‐C ₄ H ₈ and n‐C ₄ H ₁₀ while achieving complete steric exclusion of iso‐C ₄ H ₈ and iso‐C ₄ H ₁₀ . The dual‐ligand system in CALF‐20 provides multiple cooperative binding sites for intelligent molecular recognition of linear C4 hydrocarbons, as further elucidated by theoretical calculations. Consequently, CALF‐20 demonstrates high adsorption capacities of 2.7 and 2.5 mmol g ⁻¹ for n‐C ₄ H ₈ and n‐C ₄ H ₁₀ , respectively, while effectively excluding branched isomers. Dynamic breakthrough experiments validated the capability of CALF‐20 to simultaneously produce high‐purity (>99.999%) iso‐C ₄ H ₈ and n‐C ₄ H ₁₀ in a single operational step. Moreover, subsequent desorption yielded n‐C ₄ H ₈ and n‐C ₄ H ₁₀ with instantaneous purity exceeding 99.99%. This work establishes a DLD‐inspired materials design paradigm, providing a groundbreaking and generalizable strategy for the efficient sieving separation of similarly challenging isomeric gas systems.