Kinetics and Mechanism of CO2 Absorption into a Novel Biphasic 1-Pentanol Solution of 2-Amino-2-methyl-1-propanol and Piperazine

The absorption kinetics of CO2 into a novel nonaqueous mixture of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) was studied at atmospheric pressure. The effects of AMP/PZ molar ratio, total concentration, absorption temperature, and inlet flow rate were discussed. The results showed that the composite absorbent with an AMP/PZ ratio of 6:4 had a good effect on the CO2 absorption at 293 K. Unlike relevant reports at home and abroad, the solubility of CO2 in the 1-pentanol solution of AMP and PZ (AMP-PZ-Pentanol) was calculated based on a solution rule model and relevant data from Aspen Plus. The absorption kinetics of CO2 into nonaqueous composite absorbent was analyzed by a double stirred-cell absorber. It shows the enhancement factor increases with the increasing of total concentration but decreases with the increasing of absorption temperature. The absorption mechanism of CO2 in AMP-PZ-Pentanol was determined to be the formation of carbamate by FT-IR, 13C NMR, and XRD analysis. Based on the vapor–liquid equilibrium theory, the reaction heat of CO2 into the phase change absorbent was calculated to be 9.30 KJ mol–1. The results show that the composite absorbent has a lower reaction heat than any single component in it. The desorption experiment of saturated solution shows that the composite absorbent can be completely regenerated in a short period of time, which meets the industrial requirements for CO2 absorbents and will provide a theoretical basis for further industrial applications of this type of absorbent.