Abstract
The present work aims at investigating absorption of CO2 into promoted and unpromoted aqueous K2CO3. For this we performed a series of lab experiments in a thermostated batch stirred tank gas-liquid reactor containing the solvent. The absorption of CO2 was monitored by the decrease in the reactor pressure. To compare the different solvent blends, the experimental conditions, i.e., injection pressure, reactor temperature, stirring speed, and solvent volume were kept constant. For the interpretation of the experiments a simple absorption model is formulated based on which an apparent absorption rate is derived. Among the different rate promoters studied, we found that V2O5 results in a substantial increase of the absorption rate, while the use of B(OH)3 in conjunction with V2O5 does not provide any tangible benefits. A semi-qualitative comparison with rate constants reported in the literature suggests that this hindering effect of B(OH)3 is due to the lower pH of the solvent containing B(OH)3. The solvent blends containing amine-promoters MEA and piperazine demonstrated rapid absorption. Comparison with the literature indicates that absorption in the presence of these promoters is mass transfer limited under the experimental conditions.
