Chemical Absorption of Carbon Dioxide into Aqueous Piperazine Solutions Using a Stirred Reactor

Abstract

In this work, the absorption of CO2 using aqueous piperazine (PZ) solution have been investigated both experimentally and theoretically. The absorption experiments were carried out in a stirred batch contactor with two flat blades. The experimental data are obtained over the temperature range of 298–338 K and for the PZ concentration, CO2 partial pressure, and the stirrer speed in the range of 0.5–1.5 kmol/m3, 2.5-7.5 bar, and 0-300 rpm, respectively. The influences of each variable upon the absorption flux, removal efficiency, and loading of CO2 have been investigated. In addition, a model based on chemical equilibrium in the liquid phase is employed to evaluate the concentration of chemical species in the liquid phase. Evidence suggests that CO2 absorption flux, removal efficiency, and the loading increase with decreasing the temperature and increasing the stirrer speed. When PZ concentration is increased, the absorption flux and removal efficiency increase and CO2 loading reduce. Also by increasing PZ concentration from 0.5 to 1.5 M at a temperature of 388 K, absorption efficiency is increased from 70 % to 95 %. CO2 absorption flux was decreased from about 0.0175 to 0.01 mol/m2 s when CO2 loading was increased from 0.32 to 0.51.

Keywords

• chemical absorption
• carbon dioxide
• piperazine solution
• stirred reactor