New amines for reactive absorption of CO 2 from process gases were investigated in a comprehensive experimental screening. All studied amines are derivates of triacetoneamine and differ only in the substituent of the triacetoneamine ring structure. The amines are abbreviated by the acronym EvA with a consecutive number, designating the derivate. About 50 EvAs were considered in this work from which 26 were actually synthesized and investigated in aqueous solution. The mass fraction of the amines in the unloaded solution was eitherw 0 EvA = 0.05 g/g orw 0 EvA = 0.4 g/g. The following properties were studied: solubility of CO 2 , rate of absorption of CO 2 , liquid-liquid and solid-liquid equilibrium, foaming behavior, dynamic viscosity, and acid constants. The nine most promising EvAs were evaluated with the NoVa short-cut method [1]. The method yields estimates for the specific energy demand and recirculation rate for a given purification task. Two typical purification tasks were considered: the CO 2 -removal from natural gas and from synthesis gas, respectively. Some of the EvAs showed significantly improved performance compared to monoethanolamine (MEA) and a solvent-blend of methyl-diethanolamine and piperazine (MDEA/PZ).

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.

The reaction kinetics of the heterogeneously catalyzed esterification of n-hexyl acetate were measured using both a batch reactor and continuous stirred tank reactor (CSTR). The catalyst was Amberlyst CSP2. The results of the batch reactor and CSTR experiments were compared to reaction kinetic measurements carried out in previous work using a plug-flow reactor (PFR). Because the change in the composition of the reaction mixture in the batch reactor is caused not only by reaction but also by component-specific adsorption on the catalyst, the batch reactor is not recommended for reaction kinetic measurements of the present type of chemical system. The results from the CSTR and PFR are in very good agreement with regard to the measured rate of reaction. To address the impact of the conditions present in a heterogeneously catalyzed reactive distillation (HCRD) column on the performance of the catalyst, the influences of boiling and of the reduction of the low-boiling components (here, water) on the rate of reaction were investigated using the CSTR. Neither was found to have a significant impact on the performance of the catalyst. A simple pseudohomogeneous model was fitted to the data of the CSTR experiments using a reparameterized Arrhenius equation to avoid parameter coupling. The model predictions and experimental results are in good agreement.

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