First Measurements for the Simultaneous Sorption of Difluoromethane and Pentafluoroethane Mixtures in Ionic liquids Using the Integral Mass Balance Method

Multicomponent absorption measurements are notoriously difficult both experimentally and analytically, which is why the literature is lacking information, even though the results are important for understanding real separation systems. In the case of designing a separation process for hydrofluorocarbon (HFC) refrigerant mixtures using an ionic liquid (IL), it is important to understand multicomponent effects; however, almost all published results are for single component HFC/IL systems. To address this challenge, new gravimetric microbalances utilizing the Integral Mass Balance (IMB) method have been designed by Hiden Isochema to efficiently and accurately measure multicomponent gas sorption in liquids with low volatility (e.g., ILs) and solids. The present work investigates the mixture absorption of difluoromethane (HFC-32) and pentafluoroethane (HFC-125) in two ILs (1- n -butyl-3-methylimidazolium tetrafluoroborate and 1- n -butyl-3-methylimidazolium hexafluorophosphate) at 298.15 K for the purpose of understanding HFC mixture/IL interactions. For the first time, these state-of-the-art instruments have allowed for the measurement of an HFC binary gas mixture in ILs that can be compared with existing single gas solubility measurements.