The effect of membrane pores wettability on CO2 removal from CO2/CH4 gaseous mixture using NaOH, MEA and TEA liquid absorbents in hollow fiber membrane contactor

The present paper renders amodeling and a 2D numerical simulation for the removal of CO2 from CO2/CH4 gaseous stream utilizing sodium hydroxide (NaOH), monoethanolamine (MEA) and triethanolamine (TEA) liquid absorbents inside the hollow fiber membrane contactor. Counter-current arrangement of absorbing agents and CO2/CH4 gaseous mixture flows are implemented in the modeling and numerical simulation. Non-wetting and partial wetting modes of operation are considered where in the partial wetting mode, CO2/CH4 gaseous mixture and liquid absorbents fill the membrane pores. The deteriorated removal of CO2 in the partial wetting mode of operation is mainly due to the mass transfer resistance imposed by the liquid in the pores of membrane. The validation of numerical simulation is done based on the comparison of simulation results of CO2 removal using NaOH and experimental data under non-wetting mode of operation. The comparison illustrates a desirable agreement with an average deviation of less than 5%. According to the results, MEA provides higher efficiency for CO2 removal in comparison with the other liquid absorbents. The order for CO2 removal performance is MEA > NaOH > TEA. The influence of non-wetting and partial wetting modes of operation on CO2 removal are evaluated in this article as one of the novelties. Besides, the percentage of CO2 sequestration as a function of gas velocity for various percentages of membrane pores wetting ranging from 0 (non-wetting mode of operation) to 100% (complete wetting mode of operation) is studied in this research paper, which can be proposed as the other novelty. The results indicate that increase in some operational parameters such as module length, membrane porosity and absorbents concentration encourage the removal percentage of CO2 from CO2/CH4 gaseous mixture while increasing in membrane tortuosity, gas velocity and initial CO2 concentration has unfavorable influence on the separation efficiency of CO2. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.