VLE measurement and modelling of absorbents for absorption of CO2

Abstract

Two promising solvents were studied for possible use as absorbents in CO2 post combustion capture. The two solvents tested were 3-(Diethylamino)-1,2-propanediol (DEA-12-PD) and 1-(2-Hydroxyethyl)piperidine (12-HEPP). A third amine N-tert- Butyldiethanolamine (N-tBDEA) was also tested for another project and compared with the two main amines.

Ebulliometer was used for measurements of pure DEA-12-PD and 12-HEPP, and then used in regression of the Antoine equations. The plot of the Antoine equations showed that 12-HEPP is the most volatile, while N-tBDEA is the least volatile compound, but all the amines tested were less volatile than MEA. VLE measurements of binary amine and water systems were also performed, and samples were taken. The samples were analyzed and quantified by amine titration.

The Antoine equations and NRTL model of the measured VLE data were carried out by the in-house program, Parafinder. The model required critical properties, which were estimated from the Joback method, since those properties were not available experimentally. The result of the NRTL model were evaluated by the AARD of the total pressure. The AARD provided the fitness of the model to the experimental data. The AARD of the total pressure for DEA-12-PD, 12-HEPP and N-tBDEA are respectively 1.82 %, 2.46 % and 1.73 %.