Experimental studies and rate-based simulations of CO2 absorption with aqueous ammonia and piperazine blended solutions

Piperazine (PZ) is a potential promoter for CO2 absorption with aqueous ammonia (NH3) solutions. Here, we focus on the performance of a blended NH3/PZ solution for CO2 capture using a laboratory-scale packed column to analyse the effects of key operating parameters, including NH3 and PZ concentration, absorption temperature and solution flow rate. A rigorous, rate-based model was developed in Aspen Plus and validated against the experimental results. Using the model, we predicted the CO2 capture process under experimental conditions to gain insight into CO2 absorption with NH3/PZ blended solutions. The addition of PZ to aqueous NH3 markedly increased CO2 absorption, achieving a CO2 removal efficiency comparable to that of monoethanolamine-based capture processes. However, the presence of PZ also increased the temperature along the column and the concentration of free NH3 in the solution, leading to a high NH3 loss from the absorber.