Enabling C₂H₂/CO₂ Separation Under Humid Conditions with a Methylated Copper MOF

As a unique subclass of metal-organic frameworks (MOFs), MOFs with open metal site (OMS) are demonstrated efficient gas separation performance through pi complexation with unsaturated hydrocarbons. However, their practical application faces the challenge of humidity that causes structure degradation and completive binding at the OMS. In this work, the effect of linker methylation of a copper MOF (BUT-155) on the C₂H₂/CO₂ separation performance under humid condition is evaluated. The water adsorption isotherm, adsorption kinetics, and breakthrough under dry and humid conditions are performed. The BUT-155 with methylated linker exhibits lower water uptake and adsorption kinetics under humid condition (RH = 20%), in comparison with HKUST-1. Therefore, the C₂H₂/CO₂ separation performance of BUT-155 is much less affected by water, especially under higher gas flow rate. Moreover, the dynamic C₂H₂/CO₂ separation performance of BUT-155 can maintain five breakthrough cycles under humid conditions (RH = 20% and RH = 80%) without obvious performance degradation.