Scalable copper-based coordination frameworks with tailored pore chemistry for energy-efficient C2H2/CO2 separation

Abstract

The separation of C₂H₂/CO₂ mixtures for acetylene purification presents both industrial significance and fundamental challenges due to their nearly identical kinetic diameters and similar physical properties. This study demonstrates the effectiveness of ultramicroporous metal–organic frameworks (MOFs) in addressing this challenge through precise pore confinement effects. We introduce two ultramicroporous materials, Cu(cyhdc) and Cu(bdc), and assess their ability to capture C₂H₂. Under ambient conditions, Cu(cyhdc) and Cu(bdc) exhibit C₂H₂ uptakes of 1.92 mmol g⁻¹ and 1.44 mmol g⁻¹, respectively. The most promising candidate is Cu(cyhdc), which possesses a C₂H₂/CO₂ selectivity of 8.45 at 298 K and 1 bar. Grand canonical Monte Carlo simulations revealed that the enhanced performance originates from multiple van der Waals interactions between C₂H₂ molecules and the curved cyclohexane-derived pore walls of Cu(cyhdc). Importantly, dynamic breakthrough experiments and scalable synthesis processes validated the practical separation potential of Cu(cyhdc) for C₂H₂/CO₂ mixtures. This work provides both mechanistic insights into gas–framework interactions and a potential solution for energy-efficient acetylene purification.

Keywords: C₂H₂/CO₂ separation; Ultramicroporous; Metal–organic framework; Pore confinement; Scalable synthesis.