Doubling CO2/N2 separation performance of CuBTC by incorporation of 1-n-ethyl-3-methylimidazolium diethyl phosphate

Abstract

1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) was incorporated into copper benzene-1,3,5-tricarboxylate, CuBTC. Consequences of molecular interactions on the CO2 separation performance of CuBTC were investigated. Scanning electron microscopy and X-ray diffraction results showed that the surface morphology and crystal structure of CuBTC remained intact upon the incorporation of the ionic liquid (IL); and the results of thermogravimetric analysis and infrared spectroscopy indicated the presence of interactions between the anion of the IL and the open metal sites of CuBTC. Gas adsorption measurements for the pristine CuBTC and IL-incorporated CuBTC were performed at 25 °C in a pressure range of 0.1–1 bar. Data showed that ideal CO2/CH4 and CO2/N2 selectivities of IL-incorporated CuBTC were 1.6- and 2.4-times higher compared to those of the pristine CuBTC at 0.01 bar, respectively. Moreover, for the CO2/CH4:50/50 and CO2/N2:15/85 mixtures, the corresponding selectivities were improved by more than 1.5- and 1.9-times compared to that of pristine CuBTC at 0.01 bar, respectively.