New Amine Blends for Improved CO₂ Separation: A Study on Reaction Kinetics and Vapor–Liquid Equilibrium

Abstract

Gas cleaning will be more eco-friendly if the absorbents used for CO₂ capture are prepared from renewable supplies such as ethanol. Ethylene diamine (EDA), N-ethylmonoethanolamine (EMEA), N-ethyldiethanolamine (EDEA), and N,N′-diethylmonoethanolamine (DEMEA) represent this class of solvents. We selected two new blends from this group: EDEA + EMEA and DEMEA + EDA. Thus, a high-capacity tertiary amine (EDEA or DEMEA) was mixed with a very reactive amine (EMEA or EDA). Using a stirred cell, we analyzed kinetics of the CO₂ reaction with these blends in aqueous solutions (2–3 M) at 308 K. On the whole, two reactions ensued in parallel: one, between CO₂ and EDEA (or DEMEA), and the other, between CO₂ and EMEA (or EDA). We evidenced that DEMEA and DEMEA + EDA were more reactive than EDEA and EDEA + EMEA. We reported the rate constant for EMEA and EDA (4700 and 28,300 M⁻¹ s⁻¹). Finally, we presented vapor–liquid equilibrium data for the DEMEA + EDA blend.

Keywords:

• Absorption kinetics
• CO₂ capture
• Mass transfer
• Vapor–liquid equilibrium