Thermodynamic modeling and energy analysis of a polyamine-based water-lean solvent for CO₂ capture

Amine-based water-lean solvents are considered to be promising energy-saving alternatives to existing aqueous amine solvents for CO₂ capture. Herein, we propose water-lean solvents comprising 3,3′-iminobis(N,N-dimethylpropylamine) (60 wt%), water (10–18 wt%), and a non-amine chemical (balance), probe the solubility of CO₂ therein, and perform the energy demand analysis using an Aspen Plus®-based simulator. For CO₂ solubility modeling, the e-NRTL model and Redlich-Kwong state equation were incorporated with the equilibrium reaction model proposed by previous researchers, and the Henry's law constant of CO₂ was estimated using molecular dynamics simulation as it is difficult to measure experimentally. Experimental data acquired using an equilibrium cell and ¹³C/¹H NMR were used to regress the equilibrium reaction model. The minimum thermal energy demand under desorber pressures of 303 and 505 kPa was calculated to be as low as 1.99 and 1.95 GJ t-CO₂⁻¹, respectively, which supports the suitability of the developed WLSs for post-combustion CO₂ capture.