Solubility measurements of carbon dioxide and nitrous oxide in an aqueous mixture of 2-dimethylaminoethanol and N-methyl-1,3-propanediamine

Aqueous monoethanolamine (MEA) is a mature post-combustion CO 2 capture technology, but it faces significant drawbacks including corrosivity, high regeneration energy (~4 GJ/t-CO 2 ), and reactivity with contaminants. This study investigates an aqueous blend of 2-Dimethylaminoethanol (DMAE, 30% wt.) and N-Methyl-1,3-propanediamine (MAPA, 10% wt.) as an alternative solvent to capture CO 2 . Given the scarcity of Vapour-Liquid Equilibrium (VLE) data for such amine blends, this research aims to expand the thermodynamic understanding of this specific aqueous DMAE + MAPA system. We thoroughly investigate its VLE with CO 2 and N 2 O across temperatures between (313.15–393.15) K. The physical solubility of CO 2 was determined using the N 2 O/CO 2 analogy. N 2 O solubility measurements were conducted in a monobloc equilibrium cell from 1 to 5 MPa. The expanded relative uncertainty of the N 2 O solubility, expressed in molality, was estimated to be 0.8% ( k = 2). Henry's constants were derived using Krichevsky-Ilinskaya analysis and CO 2 solubility was determined using a static-isochoric Van Ness-type apparatus over 313.15–363.15 K and up to 7 MPa with a relative uncertainty of u r ( α exp ) = (0.3–5) %. Finally, speciation profiles and the heat of CO 2 absorption were predicted using established thermodynamic models optimized for this system. • CO 2 and N 2 O solubility measured for a defined DMAE-MAPA aqueous blend. • Henry's constant obtained using N 2 O-CO 2 analogy. • High-accuracy density data support high-pressure VLE analysis. • Model γ − ϕ reproduces CO 2 solubility with low relative deviation. • Reduced heat of absorption indicates energy-efficient solvent design.