Density, Viscosity, and Performances of Carbon Dioxide Capture in 16 Absorbents of Amine + Ionic Liquid + H2O, Ionic Liquid + H2O, and Amine + H2O Systems

A series of novel ionic liquids, 2-aminoethanol tetrafluoroborate ([MEA][BF4]), 2-[2-hydroxyethyl(methyl)amino] ethanol tetrafluoroborate ([MDEA][BF4]), 2-[2-hydroxyethyl(methyl)amino] ethanol chloride ([MDEA][Cl]), 2-[2-hydroxyethyl(methyl)amino] ethanol phosphate ([MDEA][PO4]), and 2-[2-hydroxyethyl(methyl)amino] ethanol sulfate ([MDEA][SO4]), were synthesized and characterized for carbon dioxide capture in this work. Densities and viscosities of ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, [MEA][BF4], [MDEA][BF4], [MDEA][Cl], [MDEA][PO4], and [MDEA][SO4]), amines + ionic liquids + H2O, ionic liquids + H2O, and amines + H2O were measured at temperatures ranging from (303.15 to 343.15) K at different mass fractions. These 16 different absorbents were prepared by mixing two or three compounds of 2-aminoethanol (MEA), 2-[2-hydroxyethyl(methyl)amino] ethanol (MDEA), 2-[bis(2-hydroxyethyl)amino] ethanol (TEA), ionic liquids, and water. The carbon dioxide capture rate and carbon dioxide capture capacity in the 16 different absorbents were measured at 303.15 K and 1.50 MPa. The experimental results showed that the viscosities of these absorbents are less than 17.00 mPa·s at 303.15 K. Among these absorbents, the MDEA + [MDEA][Cl] + H2O + piperazine system shows the best performance on carbon dioxide capture.