ABSORPTION OF CO₂INTO AQUEOUS SOLUTIONS OF STERICALLY HINDERED METHYL AMINOETHANOL USING A HYDROPHOBIC MICROPOROUS HOLLOW FIBER CONTAINED CONTACTOR

Abstract

The absorption of dilute CO 2 into aqueous solutions of sterically hindered 2-methyl aminoethanol (MAE) and the desorption of CO 2 from CO 2 -loaded MAE solutions into N 2 stream were investigated separately for the various combinations of operational variables, using a hydrophobic microporous hollow fiber (polytetrafluoroethylene, PTFE) contained gas-liquid contactor with aqueous solutions of MAE as liquid media in the shell side at 30 C. The absorption of CO 2 in this contactor is governed by resistance in the liquid and hollow fiber phases. The resistance to diffusion in the hollow fiber phase amounts to 76-80% of the total resistance. Nevertheless, the absorption rates of CO 2 into aqueous MAE solutions in this contactor are higher than those into aqueous solutions of sterically hindered 2-amino-2-methyl-1-propanol (AMP) in the stirred tank with a plane unbroken gas-liquid interface. The process of desorption of CO 2 from CO 2 -loaded MAE solutions can be regarded as being controlled by diffusion and chemical reaction in both the stagnant film of the liquid phase and the liquid-filled pore of the hollow fiber phase under the slow or intermediate reaction regime. Both absorption and desorption rates under the simultaneous absorption-desorption operation in a single unit tend to approach the respective constant values as process time elapses. The total absorption rate here seems to be almost balanced with the total desorpion rate at the constant mass transfer rate periods.

Chemical absorption of carbon dioxide with asymmetrically heated polytetrafluoroethylene membranes

“…PTFE membranes were used to recover CO 2 in previous literature (Yeon et al, 2003;de Montigny et al, 2006;Shimada et al, 2006). Yeon et al (2003) studied the mass transfer of CO 2 absorption in PVDF and PTFE membrane contactors.…”

“…They obtained the overall mass transfer coefficient K L of about 1e2 Â 10 À4 m s À1 ([CO 2 ] ¼ 0.001 mol dm À3 , et al (2006) used polypropylene (PP) and PTFE membranes in a membrane contactor for CO 2 absorption. They obtained a CO 2 flux of 3.8 Â 10 À10 kmol s À1 m À2 ([CO 2 ] ¼ 9%, [MEA] ¼ 2 mol dm À3 , PTFE, Shimada et al (2006) studied CO 2 absorption using AMP and obtained a CO 2 flux of 0.2 Â 10 À6 kmol s À1 m À2 with PTFE hollow fiber membranes ([CO 2 ] ¼ 5e10%, [AMP] ¼ 1 mol dm À3 , PTEF, e ¼ 0.5, dp ¼ 0.45 mm, t ¼ 0.5 mm). Those differences may be due to the differences in the type of absorbents, absorbent concentration, pore size, and thickness of the membranes.…”

Absorption of carbon dioxide by the absorbent composed of piperazine and 2-amino-2-methyl-1-propanol in PVDF membrane contactor

“…Compared the b value with other study, Shimada et al (2006) studied the CO 2 absorption using sterically hindered methyl aminoethanol (MAE) in polytetrafluoroethylene (PTFE). They found the liquid penetration into pores of hydrophobic microporous hollow fibers was about 0.06-0.116%.…”

“…NaOH (2 M) system in 0.051 m HFMM, he found the membrane and gas phase resistance to be 35 and 60%. Shimada et al (2006) studied the CO 2 absorption using MAE in polytetrafluoroethylene. They reported that the resistance of membrane diffusion amounted to 76-80% of the total resistance.…”

Effects of shape, porosity, and operating parameters on carbon dioxide recovery in polytetrafluoroethylene membranes

“…de Montigny et al [8] used polypropylene and PTFE membranes in a membrane contactor for CO 2 absorption. Shimada et al [9] studied CO 2 absorption using AMP with PTFE membrane. However, the broad pore size distribution, membrane thickness and larger pore size of commercial PTFE restrict its application in CO 2 absorption.…”