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

Abstract

A series of novel ionic liquids, 2-aminoethanol tetrafluoroborate ([MEA][BF 4 ]), 2-[2-hydroxyethyl(methyl)amino] ethanol tetrafluoroborate ([MDEA][BF 4 ]), 2-[2-hydroxyethyl(methyl)amino] ethanol chloride ([MDEA][Cl]), 2-[2-hydroxyethyl(methyl)amino] ethanol phosphate ([MDEA][PO 4 ]), and 2-[2-hydroxyethyl(methyl)amino] ethanol sulfate ([MDEA][SO 4 ]), were synthesized and characterized for carbon dioxide capture in this work. Densities and viscosities of ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, [MEA][BF 4 ], [MDEA][BF 4 ], [MDEA][Cl], [MDEA][PO 4 ], and [MDEA][SO 4 ]), amines + ionic liquids + H 2 O, ionic liquids + H 2 O, and amines + H 2 O 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] + H 2 O + piperazine system shows the best performance on carbon dioxide capture.