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).

Aqueous solutions of N,N-dimethyl-dipropylene-diamino-triacetonediamine (EvA34) are promising solvents for CO 2 capture. Therefore, in the present work, a comprehensive experimental study was carried out to determine data on physico-chemical properties of EvA34 and its mixtures with H 2 O and CO 2 . The liquid density and the dynamic viscosity was studied for pure EvA34, as well as for unloaded and CO 2 -loaded 1 aqueous solutions of EvA34. The liquid heat capacity was studied for pure EvA34 and unloaded aqueous solutions of EvA34. Furthermore, data on the vapor pressure of pure EvA34 was recorded. The pH-value was measured for unloaded and CO 2 -loaded aqueous solutions of EvA34 and the dissociation constants of EvA34 were determined from titration curves. Moreover, data on the solubility of CO 2 in aqueous solutions of EvA34 and data on the CO 2 -containing species in the liquid phase of these solutions were recorded. Most of the new data was taken at temperatures between 293 and 393 K. The mass fraction of EvA34 in the unloaded aqueous solutions was eitherw 0 EvA34 = 0.1 g/g orw 0 EvA34 = 0.4 g/g. The CO 2 -loading was up toα CO 2 = 6.2 mol/mol. The new data were compared to corresponding data of two standard amines that are used for CO 2 capture: monoethanolamine (MEA) and a blend of methyl-diethanolamine and piperazine (MDEA/PZ). The comparison revealed that EvA34 combines favorable properties of MEA and MDEA/PZ in one molecule.

In a recent study, we have shown by NMR spectrocopy that monoalkylcarbonates are formed in substantial amounts in aqueous solutions of the tertiary alkanolamine methyldiethanolamine (MDEA) upon loading with carbon dioxide (CO 2 ). These species had been overlooked by most authors previously. In the present work, this study was extended to the primary alkanolamine monoethanolamine (MEA). Also here monoalkylcarbonates were found, but only at CO 2 loadings above 0.5 mol CO 2 per mol MEA. Both the amine and its carbamate form monoalkylcarbonates. The concentration of the monoalkylcarbonates was determined with 13 C NMR spectroscopy in a wide range of CO 2 loadings, MEA concentrations, and temperatures. Based on this comprehensive data the chemical equilibirium constants of the formation of the monoalkylcarbonates were determined.

A new short-cut method (NoVa) for assessing solvents for gas cleaning by reactive absorption is presented. It considers the absorption / desorption cycle using the assumption of infinite number of stages in both columns. For a given feed and removal rate, the method yields an estimate for the specific regeneration energy q as a function of the solvent circulation rate L G. The sole solventdependent input consists of two correlations describing the gas solubility at absorber and desorber conditions and estimates of caloric properties. Furthermore, a simple equation (SolSOFT) for correlating the gas solubility as a function of the gas loading of the solvent is presented. A theoretical analysis of the process reveals general properties of the dependency of q on L G. The NoVa method is described and tested using amine-based solvents for post combustion carbon capture as examples.

New amines for reactive absorption of CO2 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 following properties were studied: solubility of CO2, rate of absorption of CO2, 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 (Vasiliu et al., 2020). The method yields estimates for the specific energy demand and recirculation rate for a given purification task. Two typical purification tasks were considered: the CO2-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).

Solvent systems with liquid–liquid phase split are potentially interesting for designing advanced CO2 absorption processes. However, physico-chemical data for assessing the benefits of such processes are scarce in the literature. Therefore, a comprehensive study on thermodynamic properties of such a system (N,N-diethyl-propylamine-triacetonediamine (EvA25) + H2O + CO2) was carried out in the present work. More than 750 experimental data points of different physico-chemical properties of that system were taken at temperatures between 20 and 120 °C, pressures of up to 75 bar, and CO2 loadings of up to 3 mol/mol. They comprise data for liquid–liquid equilibrium, CO2 solubility, liquidus temperature, chemical speciation, heat capacity, density, viscosity, and vapor pressure. The liquid–liquid phase split occurs at elevated temperatures and reduces the solubility of CO2 in the solvent. The organic liquid phase contains only little CO2, so that only the aqueous phase has to be regenerated. Based on the new data, options for using the liquid–liquid phase split in the design of CO2 absorption processes are discussed.

Aqueous solutions of N,N-dimethyl-dipropylene-diamino-triacetonediamine (EvA34)are promising solvents for CO2 capture. Therefore, in the present work, a compre-hensive experimental study was carried out to determine data on physico-chemicalproperties of EvA34 and its mixtures with H2O and CO2. The liquid density and thedynamic viscosity was studied for pure EvA34, as well as for unloaded and CO2-loaded aqueous solutions of EvA34. The liquid heat capacity was studied for pure EvA34and unloaded aqueous solutions of EvA34. Furthermore, data on the vapor pressure ofpure EvA34 was recorded. The pH-value was measured for unloaded and CO2-loadedaqueous solutions of EvA34 and the dissociation constants of EvA34 were determinedfrom titration curves. Moreover, data on the solubility of CO2 in aqueous solutions ofEvA34 and data on the CO2-containing species in the liquid phase of these solutionswere recorded. Most of the new data was taken at temperatures between 293 and 393K. The mass fraction of EvA34 in the unloaded aqueous solutions was either ~ w0EvA34= 0.1 g/g or ~ w0EvA34 = 0.4 g/g. The CO2-loading was up to ~?CO2 = 6.2 mol/mol. Thenew data were compared to corresponding data of two standard amines that are usedfor CO2 capture: monoethanolamine (MEA) and a blend of methyl-diethanolamineand piperazine (MDEA/PZ). The comparison revealed that EvA34 combines favorableproperties of MEA and MDEA/PZ in one molecule.

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