CO2 absorption into 4-diethylamino-2-butanol solution in a membrane contactor under wetting or non-wetting conditions

Natural gas produces a large amount of carbon emissions in the process of mining and processing, on the one hand from the energy use of processing facilities, on the other hand from the way that natural gas is extracted. The adoption of appropriate carbon capture technology is of urgency. The membrane absorption method has recently been attracted much attention and studied by the majority of researchers worldwide. Because it overcomes many shortcomings compared with the conventional absorber, and has the advantages of large gas-liquid contact area and small size. In this paper, a hollow fiber membrane contactor (HFMC) is used to simulate the decarburization process by using 4-diethylamino-2-butanol (DEAB) solution. As a new type of alcohol amine solvent, DEAB solvent has excellent absorption and regeneration performance, and also has the characteristics of low energy consumption and high energy efficiency, which exhibits a strong development potential in the field of gas absorption. In this work, a mathematical model of the gas and liquid reaction and transport in HFMC under wetting and non-wetting conditions was established. In this model, the countercurrent process of the absorbent and natural gas is adopted, and four solvents (i.e., DEAB, monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA)) are used to absorb CO2 from natural gas containing 10 vol.% CO2 and 90 vol.% CH4. Moreover, the effect of membrane wettability on the CO2 removal performance by different absorbents are studied. The results show that the wetting of the membrane pores greatly reduced the absorption efficiency under the same conditions. The decarburization efficiency under the non-wetting mode is 342% of the fully wetting case. Increasing the flow rate and concentration of the absorbent can improve the decarburization performance. The increase in the inner diameter of HFMC also significantly improved the decarburization capacity within a certain range. The inlet temperature and gas flow rate had an adverse effect on the CO2 removal.