Complete body of DFT-MD results, results of Monte Carlo simulations, setup and results of microkinetic modeling, additional experimental details and results (PDF) CatMAP files (ZIP) ■ AUTHOR INFORMATION

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2-Amino-2-methyl-1-propanol (AMP) and the blends of AMP with other amines appear to be commercially attractive solvents for postcombustion CO 2 capture by absorption/stripping. Oxidative degradation experiments involving AMP aqueous solutions were performed in a 200 mL glass batch reactor with initial AMP concentrations of 5 mol•kg −1 , oxygen partial pressures of 250−350 kPa, and at temperatures of 100−140 °C in order to elucidate the degradation mechanistic pathways. The amine loss was determined by cation ion chromatography (IC), while the degradation compounds were identified and quantified by gas chromatography−mass spectrometry (GC−MS) and anion IC. The possible chemical pathways of AMP oxidative degradation are proposed on the basis of the identified and quantified products and the context of the current amine degradation schemes. The role of O 2 in the proposed pathways is much more explicit than the previously proposed MEA oxidation mechanisms.

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The amine carbamate related equilibrium (RNHCOO − + H 2 O ⇆ RNH 2 + HCO 3 − ) has been investigated with 13 C NMR (Nuclear Magnetic Resonance) spectroscopy for a series of linear primary alkanolamines, and the apparent carbamate decomposition equilibrium constants have been estimated. A quantitative NMR method for the calculation of the concentration of the species formed in solution has been provided, including the assessment of each of the fast exchanging proton species (whose nuclei resonate at the same chemical shifts in the NMR spectra). For this purpose, NMR-based calibration curves were utilized and an alternative method was applied for validation. The overall results showed that the amount of carbamate found at the equilibrium decreased as the length of the carbon chain increased, while the corresponding apparent carbamate decomposition equilibrium constants featured the same order of magnitude (10 −2).

The diamine 3-(Methylamino)propylamine (MAPA) and eight tertiary amines were studied as single and blended aqueous CO2 absorbents at different concentrations and ratios to investigate the reaction mechanisms. After absorption (40 °C) and desorption (80 °C) experiments, quantitative 13 C NMR experiments were performed on each liquid sample.After absorption, the following CO2-derived species were identified and quantified:(bi)carbonate in each amine system; primary and secondary MAPA carbamate, and MAPA dicarbamate in MAPA-systems; tertiary amine carbonate in tertiary amine-systems.Concerning desorption, the main CO2-species removed was (bi)carbonate, followed in the blends by MAPA dicarbamate.Since, after CO2 absorption, the concentration of MAPA dicarbamate was negligible in single MAPA and, in the blends, mainly increased at increasing pKa of the tertiary amines, it is concluded that the tertiary amines increase the availability of MAPA species to react further with CO2. MAPA and tertiary amines appear to influence each other also for the CO2 release.

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