Investigation of thermophysical properties and CO2 equilibrium solubility in nonaqueous mixtures of monoethanolamine (MEA) and N,N-dimethylformamide (DMF)

To reduce CO₂ emissions and address issues with conventional amine-based aqueous absorbents, a mixed nonaqueous solution of monoethanolamine (MEA) and N,N-dimethylformamide (DMF) was proposed. The density, dynamic viscosity and refractive index of fresh MEA-DMF solutions (10-50 wt% MEA) and CO₂-loaded solutions (0.10–0.51 mol CO₂·(mol MEA)⁻¹) were measured across the temperature range of 298.15–333.15 K. The values for fresh solutions were correlated with concentration and temperature using the Jouyban-Acree model (JAM) and an exponential equation. Then the results after CO₂ absorption were derived from the CO₂ loading amount. Additionally, CO₂ absorption performance of MEA-DMF with various concentrations at 303.15–333.15 K and 9.64–134.52 kPa was assessed to determine gas-liquid equilibrium and develop semi-empirical correlations. Nuclear magnetic resonance (NMR) analysis confirmed that carbamate was the primary product formed after CO₂ absorption in the nonaqueous absorbent. These studies provide essential data for equipment design and absorbent optimization. MEA-DMF solutions demonstrate favorable viscosity and CO₂ absorption performance, supporting the potential use of nonaqueous absorbents in industrial CO₂ capture technologies.