One-step purification of ethylene by porous coordination polymers: from impurity-specific design logic to quantitative structure–property relationships

The purification of ethylene (C 2 H 4 ) constitutes a foundational yet energetically demanding operation in the petrochemical industry, where conventional separation technologies remain intrinsically energy-intensive. In recent years, adsorptive separation employing porous coordination polymers (PCPs) has emerged as a promising and sustainable alternative or transitional strategy. This review consolidates recent advances in the one-step purification of C 2 H 4 from multi-component C2 light hydrocarbon and carbon dioxide (CO 2 ) mixtures, delineated through four overarching design principles: (i) pore geometry and size engineering for molecular sieving and kinetic control; (ii) pore chemistry and functional-site engineering for thermodynamic selectivity toward impurities; (iii) pore electrostatic potential engineering for the differential recognition of impurities over C 2 H 4 ; and (iv) dynamic structural effects in flexible PCPs enabling adaptive separation. Going beyond a qualitative inventory of materials, we further translate these design principles into a set of quantitative mechanistic descriptors—including the pore-to-kinetic-diameter ratio (λ), the electrostatic potential extremum (ΔESP), the isosteric heat difference (Δ Q st ), the diffusion barrier difference (Δ E a ), and the gate-opening pressure ratio (Π)—and examine how they correlate with selectivity, capacity, and regenerability. On this basis, the review examines the process-level challenges that must be surmounted for industrial deployment and outlines prospective research directions spanning materials chemistry, process engineering, and machine learning, thereby offering mechanistic and design insights for the next generation of PCPs.