Evaluation of the absorption performance of amine-based solvents for CO2 capture based on partial oxy-combustion approach

Partial oxy-combustion technology emerges as a potential CO2 capture process that might improve the CO2 separation step using an amine-based chemical absorption process. Its main potentialities are based on the kinetic enhancement of the CO2 absorption stage that can lead to reduce the energy penalty of the overall CO2 capture. In this work, three amine families, namely primary, secondary and tertiary amines were evaluated in order to study the absorption performance in presence of CO2-enriched flue gas. The tests campaign were performed using a semi-batch lab-scale rig. The effects on the kinetic of the CO2 absorption were analysed under variations of the synthetic flue gas composition for above-mentioned solvents. The CO2 absorption was enhanced under higher CO2 concentration for all the solvents tested in terms of both the CO2 absorption rates and the CO2 loading reached at equilibrium. Amines based on the Zwitterion mechanism - primary and secondary amines - increased from 3 to 5.5 times the average CO2 absorption rates in presence of CO2 concentrations ranging between 40 and 60% v/v whereas amines based on base-catalysed hydration mechanism mainly increased the CO2 loading. The CO2 absorption capacity for tertiary amines was doubled under 60% v/v CO2. Based on these results, the contribution of tertiary amines in blends should be increase for partial oxy-combustion applications and hence further reductions might be achieved in terms of energy requirement during the solvent stripping. Finally, high performance of the CO2 absorption process was achieved for partial oxy-combustion operating at 40%v/v CO2 concentration in the flue gas.