Reactive absorption of carbon dioxide in aqueous n-methyldiethanoloamine solutions catalysed with carbonic anhydrase in a rotating packed bed (RPB)

Abstract

Studies on absorption of carbon dioxide in the rotating packed bed (RPB) were performed with two different types of metal foam packing, and two types of liquid absorbents: 30 wt.% solutions of N-methyldiethanolamine in water, with and without the addition of 0.2 wt.% of carbonic anhydrase. Different rotation speeds, gas flow rates and liquid flow rates were investigated. Results were evaluated using normalized interphase molar flow. Increased rotation speeds and phase flow rates positively affected the interphase mole flow of CO2, but high gas and liquid flow rates limited the operating window due to flooding. The addition of anhydrase significantly increased the absorption efficiency, but also narrowed the operating window. The addition of carbonic anhydrase resulted in an increase in the degree of absorption 2–5-fold for the analogous gas and liquid flow rates, compared to the amine without the biocatalyst. The highest normalized mole flow of 66.3 kmol h−1m−3 was observed for NC1116 packing with the solvent containing anhydrase, while the highest normalized mole flow for solvent without catalyst was 26.2 kmol h−1m−3. The results were compared with analogous absorption processes in a packed column and showed up to 50-fold higher mass transfer efficiency.