The mole fraction solubilities ( x *) and volumetric liquid-side mass-transfer coefficients ( k L a ) for H 2 S and CO 2 in the ionic liquid, TEGO IL K5, (a quaternary ammonium polyether) were measured under different pressures (up to 30 bar) and temperatures (up to 500 K) in a 4 L ZipperClave agitated reactor. CO 2 and N 2, as single gases, and a H 2 S/N 2 gaseous mixture were used in the experiments. The solubilities of H 2 S and CO 2 were found to increase with pressure and decrease with temperature within the experimental conditions used. The H 2 S solubilities in the ionic liquid (IL) were greater than those of CO 2 within the temperature range investigated (300−500 K) up to a H 2 S partial pressure of 2.33 bar. Hence, the IL can be effectively used to capture both H 2 S and CO 2 from dry fuel gas stream within the temperature range from 300 to 500 K under a total pressure up to 30 bar. The presence of H 2 S in the H 2 S/N 2 mixture created mass-transfer resistance, which decreased k L a values for N 2 . The k L a and x * values of CO 2 were found to be greater than those of N 2 in the IL, which highlight the stronger selectivity of this physical solvent toward CO 2 than toward N 2 . In addition, within the temperature range from 300 to 500 K, the solubility and k L a of H 2 S in the IL were greater than those of CO 2, suggesting that not only can H 2 S be more easily captured from dry fuel gas streams but also a shorter absorber can be employed for H 2 S capture than that for CO 2 .
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Heintz et al. (2009) studied this question.