Efficient inverse CO2/C2H2 separation driven by rare thermodynamic affinities difference in a porous MOF

Abstract

Separating C2H2 from CO2 is crucial in the industry of petrochemicals but extremely difficult, owing to their very close molecular sizes and similar physical characteristics. Herein, a new porous MOF with 1D rhombus channels featuring plentiful open metal sites was built. The activated framework presents a high CO2 uptake of 83.1 cm3 cm-3 at 298 K under 100 kPa and uncomon inverse selectivity for the CO2/C2H2 mixtures. What’s more, the MOF can directly yield high-purity C2H2 (≥ 99.9 %) from CO2/C2H2 mixtures (v/v = 50/50 and 10/90) under ambient conditions through single breakthrough separation process, which significantly increased the separation efficience and reduced energy consumption. The GCMC simulations revealed that highly efficient inverse CO2/C2H2 separation performance arose from the higher thermodynamic affinities for CO2 than C2H2.