Membrane-based Amino Acid Salt And Composite Solvent Absorption Of Carbon Dioxide In The Mixture

An experimental research by hollow-fiber membrane-based absorption system was carried out. The hollow-fiber polypropylene microporous membrane (HFPPM) modules were used as membrane contactors and the aqueous solution of amino acid salt and its compound solvent was chosen as the absorbent. The effect of characteristics, including concentration and flow velocity of absorbent and feeding gas, on the CO₂ absorption process has been widely investigated. And the active materials of different concentration, including Potassium phosphate tribasic, Potassium tetraborate, N-methyldiethanolamine, 2-Amido-2-methyl-l-propylacohol and Piperazine, were added in the absorbent, of which the effect has also been investigated. Operation stability of HFPPM contactor was experimented initially. The performance of the compound absorbent was predicted by mathematical model of enhancement factor. The results show that the separation of CO₂ by membrane-based amino acid salt and its compound absorbent is of quicker mass transfer velocity and higher separated efficiency. The CO₂ absorptivity of compound absorbent with amino acid salt and little additives is higher than the aqueous solution of pure amino acid salt and the compound absorbent with little Piperazine represents best in all species of absorbent. It is suitable to absorb CO₂ using 1.0 mol/L compound absorbent in which the proportion of amino acid salt and additive is 4:1. The results from the model are in good agreement with the experimental data. Potassium phosphate tribasic, Potassium tetraborate, and Piperazine are of obvious active affection for enhancement foctor, where N-methyldiethanolamine and 2-Amido-2-methyl-l-propylacohol are negative ones in all additives. To sum up, compared with the conventional absorbent, the compound absorbent provides more superiority in industrial application.