On the water stability of ionic liquids/Cu-BTC composites: an experimental study

Abstract

AbstractIonic liquids/metal-organic framework composites are recognized as promising adsorbents for CO2 capture due to the outstanding adsorption performance, whereas their water stability, which is critical for the real application of ILs/MOF composites, has not been taken into consideration. In this work, the water stability of two ILs/Cu-BTC composites, i.e., 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) /Cu-BTC and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) /Cu-BTC, were investigated. We found that the loading of ILs does not impose remarkable impacts on the crystalline structure of Cu-BTC upon water exposure; whereas the thermal stability and surface area of Cu-BTC were decreased by the incorporation of ILs, thereby leading to the reduced CO2 uptake in spite of the enhanced CO2 heat of adsorption. Furthermore, it was revealed that the decomposition of Cu-BTC occurred within the first hour of water exposure. Nevertheless, the loading of ILs retarded the decomposition of Cu-BTC according to the variations in BET surface area upon water exposure.\n Graphical abstract