Simultaneous Mass Transfer of H2S and CO2 with Complex Chemical Reactions in an Aqueous Di-isopropanolamine Solution

The absorption of H2S and CO2 into an aqueous di-isopropanolamine (DIPA) solution was studied experimentally and theoretically as an example of simultaneous mass transfer with complex reversible reactions. The absorption phenomena were classified into three regimes: (1) negligible mutual interaction between the CO2 and H2S absorption, (2) intermediate interaction, and (3) extreme interaction leading to forced desorption of one of the gaseous components, while based on its overall driving force absorption would be expected. The key parameter largely determining the transitions between these regimes is the extent of depletion of the alkanolamine in the penetration zone. In order to study these phenomena, simultaneous absorption experiments were carried out in each of the three regimes mentioned above using a stirred cell reactor and for some experiments a wetted wall column. The experimental results were evaluated by means of a numerical solution of the penetration model description of simultaneous mass transfer with complex reactions (Cornelisse et al., Chem. Eng. Sci., 35 (1980) 1245). Recently we derived a numerical film theory description, which has also been incorporated in the evaluation. The measured hydrogen sulphide fluxes fall between film and penetration theory calculations, whereas the CO2 fluxes are closer to the film theory.