Aspen Plus supported analysis of the post-combustion CO2 capture by chemical absorption using the [P2228][CNPyr] and [P66614][CNPyr]AHA Ionic Liquids

Abstract

In this work, the post-combustion CO2 chemical capture using the [P2228][CNPyr] and the [P66614][CNPyr] Aprotic Heterocyclic Anion Ionic Liquids (AHA ILs) is analyzed. To model the unit operations in the Aspen Plus commercial process simulator, a multiscale a priori COSMO-based methodology developed in our group able to include the AHA IL into the simulator database is used. This methodology takes advantages of combined quantum chemistry and statistical thermodynamics (COSMO-RS) to predict the component properties needed to include new non-databank compounds into the AspenOne process simulator suite. In Aspen Plus, the CO2 capture process to treat a multicomponent flue gas by chemical absorption is modeled. The absorption operation is simulated using the RADFRAC rigorous model of a commercial packed column both in Rate-based (mass transfer limitations considered) and Equilibrium modes. The heat of reaction and the mass transfer kinetics are considered to properly model the absorption efficiency at isothermal and adiabatic operating conditions. Tetraglyme is proposed as a co-solvent able to both improve the concentration of CO2 present in the liquid phase and minimize the mass transfer limitations. Afterward, the multicomponent desorption (CO2 and H2O must be desorbed) is analyzed at 115 °C and 1 bar. A recirculation of CO2 is proposed as stripping fluid able to reduce water partial pressure and, therefore, improve the water desorption. The complete CO2 capture process is then simulated analyzing the recycled water effects and recalculating the solvent needs. Finally, the energy and solvent expenses are compared to other CO2 capture technologies proposed in the literature.