Achieving high-performance acetylene/carbon dioxide separation via green and scalable synthesis of high-density cobalt-based MOF.

A high-density Co-based metal-organic framework (3D-PL-MOF) was successfully synthesized, featuring a heptanuclear cobalt cluster for highly efficient C2H2/CO2 separation. The material exhibits exceptional stability and significant gas uptake, achieving adsorption capacities of 66.3 cm3 g-1 for C2H2 and 49.7 cm3 g-1 for CO2 at 298 K and 1 bar. Critically, the C2H2 uptake markedly exceeds that of CO2 in the low-pressure region. Molecular simulations and calculated isosteric heats of adsorption reveal that the framework's interaction forces with C2H2 are significantly stronger than those with CO2. The 3D-PL-MOF demonstrates outstanding separation performance, enabling the recovery of high-purity C2H2 from an equimolar C2H2/CO2 mixture with a yield of 51.4 L kg-1. The stability of the material has been demonstrated through breakthrough tests under both three consecutive cycles and 50 % relative humidity conditions. Importantly, the 3D-PL-MOF is amenable to low-cost, gram-scale synthesis utilizing a simple, green water/ethanol solvent system. This work not only introduces a promising material for energy-efficient gas separation but also offers new strategies for developing adsorption separation materials that effectively combine high density with environmentally friendly synthesis.