Absorption of Carbon Dioxide Characterized by Using the Absorbent Composed of Piperazine and Triethanolamine

Abstract

ABSTRACTThis work studies the CO2 absorption of alkanolamine, piperazine, and TEA (triethanolamine), and the chemical reaction kinetics of CO2 by using the mixed solution of piperazine and TEA in polyvinylidinefluoride hollow fiber membrane contactor-stripper hybrid process. Absorption was studied from 303K to 382K in the mixed solution of piperazine 0.26 M, 0.64 M, and TEA 0.38 M, 1.13 M, 2.26 M. Also, absorption rates were measured as a function of CO2 partial pressure in the mixed solutions. The increase of the initial absorbent concentration and CO2 partial pressure showed a high absorption rate of CO2. Our experiment revealed that the absorption capacity of the mixed absorbent of TEA and piperazine with CO2 was mostly governed by the piperazine concentration. The TEA is a tertiary amine with low CO2 absorption capacity, but it helps the hollow fiber membrane keep the non-wetting condition in the fiber’s pores because of the high viscosity of TEA. Therefore, the addition of piperazine to TEA, which has too low absorption capacity with CO2, makes it possible to obtain a high CO2 removal efficiency. Finally, the kinetic data on the reaction of piperazine and CO2 were investigated, and the activation energy was calculated through the Arrhenius expression.