Thermodynamic Study of a Complex System for Carbon Capture: Butyltriacetonediamine + Water + Carbon Dioxide

Abstract

Different thermodynamic properties of aqueous solutions of butyltriacetonediamine (BuTAD), unloaded and loaded with carbon dioxide, are studied experimentally. For unloaded mixtures of BuTAD and water, protonation equilibrium constants between 283 and 333 K and liquid–liquid equilibria between 313 and 353 K, including the lower critical point, are determined at atmospheric pressure. Furthermore, the solubility of carbon dioxide in aqueous solutions of BuTAD between 313 and 393 K is determined at low loadings with an analytic method based on headspace gas chromatography and at high loadings with a synthetic method using a high pressure view cell. In the loaded system, solid precipitation, liquid–liquid phase split, and the presence of metastable states are observed in certain ranges. The data is interesting for assessing the aqueous solution of BuTAD as solvent for carbon capture. A short-cut method is used for comparing the new solvent with an aqueous solution of monoethanolamine (MEA) with respect to the energy requirement of an absorption/desorption process for CO2 scrubbing. Furthermore, a new and simple gas chromatographic method for determining the loading with carbon dioxide of aqueous solutions of amines is described.

Triacetoneamine-derivates (EvAs) for CO2-absorption from process gases

“…The number behind EvA designates the derivate. Physicochemical properties of two of these EvAs were thoroughly studied in previous works of our group [26,27].…”

Short-cut method for assessing solvents for gas cleaning by reactive absorption

“…The model of Ermatchkov et al, 14 which is based on the extended Pitzer equations, was used for calculating data points for MDEA30. The experimental data of Vasiliu et al 10 was used for BuTAD30.…”

“…Top: MEA30 (313, 353, 393) K, experimental data from Wagner et al 13 Middle: MDEA30 (313, 333, 353, 393) K, data from a physico-chemical model. 14 Bottom: BuTAD30 (313, 323, 333, 393) K, experimental data from Vasiliu et al 10 in the three solvents were determined. The integral is evaluated for the interval of the CO 2 partial pressure from 0 to 2 bar using Eq.…”

“…The SolSOFT equation and the NoVa short-cut method are thoroughly discussed for the first time in this work. Nevertheless, they have already been employed in previous studies for evaluation of solvents for carbon capture (e.g., Vasiliu et al, 10 Kessler et al 11 ).…”

“…The new amine is butyltriacetonediamine (BuTAD), and has recently been studied by our group. 10 The reference amines are monoethanolamine (MEA) and methyldiethanolamine (MDEA). The solvents were aqueous solutions with 0.3 g/g amine.…”