Antisolvent Precipitation of Potassium Bicarbonate from KHCO3 + H2O + Ethanol/2-Propanol Systems in the CO2 Capture Process

Abstract

For the energy-saving hot carbonate process, which contains a crystallization step, the antisolvent precipitation of potassium bicarbonate was investigated by adding ethanol and 2-propanol in a simulated effluent solution of CO2 absorption column. The feasibility of using the antisolvent was verified with the equilibrium data of ternary systems and a KHCO3 recovery. The ternary systems of KHCO3 + H2O + ethanol/2-propanol were equilibrated with varying amounts of alcohols at a preset temperature, and the equilibrium concentrations were determined using the cloud point method. In the ethanol system, a homogeneous and a solid–liquid phase were observed, whereas in the 2-propanol system, a liquid–liquid phase as well as the homogeneous and solid–liquid phases were observed. The equilibrium data were correlated with a local concentration parameter in the range of the antisolvent. From the correlation, the amount of antisolvent that has an effect equivalent to a cooling-only method and the optimum concentration...