화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.58, No.51, 23304-23316, 2019
Investigation into the Effective Chemical Structure of Metal-Containing Ionic Liquids for Oxygen Absorption
To control the properties of Co(II)(salen)-based metal-containing ionic liquids (MCILs) for use as O-2 absorbents, the effects of the MCIL chemical structures on viscosity, O-2 absorption amount, and complex-formation reaction rates between O-2 and MCILs were investigated. The chemical structures of the MCILs were systematically changed by coordinating the ligand ILs composed of phosphonium cations with different alkyl-chain lengths and N-methylglycinate or bis(trifluoromethylsulfonyl)imide anion to Co(salen). A series of investigations indicated that intermolecular hydrogen bonding and entanglement of the alkyl chain affected the viscosity of the MCILs. Furthermore, small MCILs afforded large O-2 absorption amounts, high O-2/N-2 absorption selectivities, and fast O-2 absorption reaction. From a numerical calculation of the overall MCIL O-2 absorption rate, it was clarified that the dominant mass-transfer resistance was the diffusion of the O-2-MCIL complex in the MCIL. Based on these results, the design criteria of the MCILs for an efficient O-2 absorbent were revealed.