CO2 capture solvent performance characterization

Abstract

The aim of this work is to determine partial pressures and CO2 loadings of primary amine aqueous solutions such as monoethanolamine, 3-amino-1-propanol, 4-amino-1-butanol and 5-amino-1-pentanol at the equal vapor liquid equilibrium conditions. Concentrations of all investigated aqueous amine solutions were kept at 30(wt)%. The temperature during the experiments was maintained 40 degrees C at close to atmospheric pressure, and CO2 loadings in the range 0.2-0.5mole CO2/mole amine. The literature review of previous works in regard to VLE in CO2-water-amine systems specifically for monoethanolamine, 3-amino-1-propanol, 4-amino-1-butanol and 5-amino-1-pentanol was carried out. The issue of the influence of structural change of amines on their capture capacities was studied in the work likewise. Literature review revealed the dependence of amine structures on CO2 loading in absorption and desorption processes. The experiments were run using an equilibrium cell connected to the gas chromatograph. Gas chromatograph was calibrated with CO2 gases correspondently to CO2 loading. The time 1 hour was permitted for CO2 absorption to ensure vapor liquid equilibrium conditions in CO2-water-amine system. Partial pressure of amines was analyzed after the extraction of the samples from equilibrium cell closed loop to gas chromatograph. CO2 loadings were analyzed with BaCl2 titration method. From two to three parallels of each sample were used to carry out the analysis. Uncertainty analysis of CO2 partial pressures and CO2 loadings was performed for all amines. Estimated vapor-liquid equilibrium curves of all amines were compared with each other. It was concluded that the cyclic capacities of investigated amines have reverse relationship to the increase of amine carbon chain length, in spite of the fact that absolute loading capacity increases with the increase of the number of carbons in carbon chain.