Hybrid behavior and mass transfer performance for absorption of CO2 into aqueous DEEA/PZ solutions in a hollow fiber membrane contactor

The carbon dioxide (CO2) capture potential of amine blends, formed by mixing N,N-Diethylethanolamine (DEEA) and piperazine (PZ), were estimated using an improved rapid screening method. Absorption and desorption experiments were carried out at 313.15 K and 353.15 K to determine the absorption rate, cyclic CO2 capacity and regeneration rate for 2 mol/L DEEA/PZ with molar ratios of 2.00:0.00, 1.50:0.50, 1.00:1.00, 0.75:1.25, 0.50:1.50, 0.25:1.75 and 0.00:2.00. Solvent screening experimental results showed that blended DEEA/PZ solution with molar ratio of 1.50:0.50 exhibited the higher CO2 absorption rate and desorption rate, thereby yielding the highest cyclic CO2 capacity of 0.8540 mol CO2/L. In addition, the experimental results also showed synergistic effects during CO2 absorption into DEEA/PZ solution, resulting in increasing absorption and desorption rates. Also, the mass transfer performance of CO2 absorption into the best 1.50 M DEEA+ 0.5 M PZ solution was investigated in a hollow fiber membrane contactor. The effects of liquid flow rate, feed temperature range, lean CO2 loading, inert gas flow rate and CO2 partial pressure on the mass transfer performance were evaluated in terms of CO2 absorption flux and overall gas phase mass transfer coefficient (KG). Furthermore, a correlation was developed for the prediction of mass transfer coefficient (KG) for CO2 absorption into DEEA/PZ solution in a hollow fiber membrane contactor. A comparison between the experimental data and the calculated values from the improved correlation demonstrated that this model is applicable to predict the CO2 absorption performance in hollow fiber membrane contactors.