Separation of High-Purity C2H2 from Binary C2H2/CO2 Using Robust Al-Based MOFs Comprising Nitrogen-Containing Heterocyclic Dicarboxylate

In this study, three nitrogen-containing aluminum-based metal-organic frameworks (Al-MOFs), namely, CAU-10pydc, MOF-303, and KMF-1, were investigated for the efficient separation of a C₂H₂/CO₂ gas mixture. Among these three Al-MOFs, KMF-1 demonstrated the highest selectivity for C₂H₂/CO₂ separation (6.31), primarily owing to its superior C₂H₂ uptake (7.90 mmol g^-1) and lower CO₂ uptake (2.82 mmol g^-1) compared to that of the other two Al-MOFs. Dynamic breakthrough experiments, using an equimolar binary C₂H₂/CO₂ gas mixture, demonstrated that KMF-1 achieved the highest separation performance. It yielded 3.42 mmol g^-1 of high-purity C₂H₂ (>99.95%) through a straightforward desorption process under He purging at 298 K and 1 bar. To gain insights into the distinctive characteristics of the pore surfaces of structurally similar CAU-10pydc and KMF-1, we conducted computational simulations using canonical Monte Carlo and dispersion-corrected density functional theory methods. These simulations revealed that the secondary amine (C₂N-H) groups in KMF-1 played a more significant role in differentiating between C₂H₂ and CO₂ compared to that of the N atoms in CAU-10pydc and MOF-303. Consequently, KMF-1 emerged as a promising adsorbent for the separation of high-purity C₂H₂ from binary C₂H₂/CO₂ gas mixtures.