Kinetics Study on Co2 Desorption of Monoethanolamine Solution

Abstract

Alcohol amine solvents are widely used in industrial applications as chemical absorbents for carbon dioxide，characterized by their low-temperature absorption and high-temperature desorption capabilities, along with high absorption capacity and simple operational processes. However, the effects of mass transfer and heat transfer during the desorption of alcohol amine rich solutions on the desorption efficiency are unclear, which limits the development of desorption equipment and the reduction of consumption during the capture process. In this work, the effects of liquid turbulence intensity and desorption temperature on the desorption rate of CO2 from monoethanolamine (MEA) CO2 rich solvents was studied in a stirred continues flow reactor. The liquid turbulence intensity was simulated by changing the stirring rate and the desorption temperature. The thermodynamic equilibrium constant of CO2 desorption was regressed according to Van’t Hoof equation. Increasing the turbulence intensity of the system reduce the bubble nucleation energy barrier of the desorption process which affecting the thermodynamics equilibrium, and it also enhance the mass transfer capacity of the solution which affecting the kinetics rate. Increasing the turbulence intensity (Rer=1530-15035) of the solution reduces the reaction energy required by the system and the macroscopic activation energy by 1.45% and 2.35%, respectively. It leads to an increase of steady-state desorption rate of CO2 by 0.41%-18.30%, while the CO2 equilibrium loading was reduced by 2.29%-5.88%. In temperature range of 347 K-373 K, the steady-state desorption rate of CO2 increased with the temperature increasing by 71%-402%, while the equilibrium loading of CO2 reduced by 29.99%–32.34%. The CO2 desorption first-order kinetic model with respect to CO2-loading is valid for temperature of 347 K-373 K and CO2 loading of 1.49 mol/L-2.76 mol/L as follows:

Keywords: CSTR, desorption, MEA, CO2 desorption kinetic model