The solubility of sulfur dioxide and carbon dioxide in an aqueous solution of potassium carbonate

This study investigates the effect of sulfur dioxide (SO2) on the removal of carbon dioxide (CO2) from a typical power station flue gas stream using an aqueous potassium carbonate (K2CO3) solvent. The influence of SO2 on the solubility of CO2 into a 30 wt% K2CO3 solution was measured using a dynamic vapour–liquid equilibrium apparatus at temperatures of 90 °C and 100 °C. The study was conducted at various loadings (moles CO2 absorbed/moles K2CO3) at atmospheric pressure using N2 as the carrier gas. It was found that SO2 preferentially reacts with K2CO3, displacing an equivalent molal quantity of CO2 into the vapor phase. An experimental analysis of the absorbed SO2 in the K2CO3 solution showed that sulfite was the major species present. Further analysis showed that the absorption of SO2 into K2CO3 solutions is a non-reversible reaction at 100 °C and hence sulfur would accumulate in the solvent and consequently over time reduce the capacity of the solvent to absorb CO2.

► This study investigates the effect of sulfur dioxide (SO2) on the removal of carbon dioxide (CO2) from a typical power station flue gas stream using an aqueous potassium carbonate (K2CO3) solvent.
► It was found that SO2 preferentially reacts with K2CO3, displacing an equivalent molal quantity of CO2 into the vapor phase.
► The absorption of SO2 into K2CO3 solutions is a non-reversible reaction at 100 °C and hence sulfur would accumulate in the solvent and consequently over time reduce the capacity of the solvent to absorb CO2.