Viscosity and density measurements of aqueous amines at high pressures: MDEA-water and MEA-water mixtures for CO₂ capture

Highlights: • Density and viscosity behavior of MDEA and MEA aqueous solutions is reported. • Measurements were carried out up to 120 MPa and four temperatures (298.15–353.15) K. • The data were correlated using Tammant–Tait and VFT models for densities and viscosities, respectively. • The fitting results are good and close to the measurement uncertainties. - Abstract: Viscosity and density are thermophysical properties crucial to characterizing any kind of fluid such as aqueous amines. These blends are becoming more and more relevant for their CO₂ capture potential, such that having accurate viscosity and density measurements would prove useful. Densities and viscosities of these mixtures at atmospheric pressure may be found in the literature although it is more difficult to find values at high pressures, these potentially proving interesting when seeking to provide a full description of these fluids. Viscosity and density measurements at high pressures (up to 120 MPa) and at temperatures between 293.15 K and 353.15 K of MDEA + water and MEA + water mixtures (both from 10% to 40% amine mass fraction) are presented in this work. Density measurements were performed with an Anton Paar DMA HPM densimeter with an expanded uncertainty (k = 2) less than ±0.7 kg·m⁻³. A falling body technique was used to measure viscosities at high pressures due to its sturdiness in terms of corrosion. Details of this latter equipment are presented, including calibration using n-dodecane and uncertainty calculations, which give a relative expanded uncertainty (k = 2) of less than ±2.4% for the highest viscosity and ±2.9% for the lowest.