Impact of Flue Gas Contaminants on Monoethanolamine Thermal Degradation

Abstract

The buildup of flue gas contaminants in amine-based postcombustion CO 2 capture processes is an important concern due to its potential impact on solvent degradation and reclaiming. In this research, in order to explore the impact of flue gas contaminants on solvent thermal degradation, sodium nitrite, fly ash, sodium sulfate, and sodium thiosulfate were each added into carbon-loaded 5.0 M monoethanolamine (MEA) solution and the solutions were exposed to high-temperature degradation conditions. MEA degrades significantly more in the presence of nitrite (5000 ppm) than MEA alone at the same amine mole concentration. The MEA degradation activation energy of MEA−nitrite solution is calculated and found to be approximately one-seventh of that of MEA solution without nitrite. Addition of nitrite not only enhanced generation of several MEA thermal degradation products but also induced formation of diethanolamine (DEA) and N-(2-hydroxyethyl)piperazin-3-one (HEPO), which have been known to form during MEA oxidative degradation. Interestingly, fly ash was observed to inhibit nitrite-induced MEA degradation and greatly increase the MEA degradation activation energy of MEA−nitrite solution. This led to a reduction in accumulation of several degradation products. Fly ash, sodium sulfate, and sodium thiosulfate by themselves were not shown to impact MEA thermal degradation rate.

Thermal Degradation Rate of 2-Amino-2-methyl-1-propanol to Cyclic 4,4-Dimethyl-1,3-oxazolidin-2-one: Experiments and Kinetics Modeling

“…As can be seen in Figure , the activation energy obtained in this work for AMP degradation to DMOZD is 129.12 kJ/mol (i.e., 30.86 kCal/mol), close to the values reported for MEA thermal degradation of 127.02 and 121.34 kJ/mol. , Based on this comparison, it appears that AMP degradation may proceed through a similar degradation pathway and is energetically very similar in comparison to MEA. ,, Also, the activation energy obtained for AMP degradation to DMOZD in this work is very low compared to the activation energy for PZ (8 m) thermal degradation of 184.1 kJ/mol . However, in terms of the pre-exponential factor, AMP thermal degradation displays 2 orders of magnitude lower value 1.69 × 10 9 , (mol/L) (1– a − b ) /s, compared to MEA, 6.27 × 10 11 (mol/L) (1– b ) /s, and 1.22 × 10 11 (mol/L)/s. , The difference in the pre-exponential factor for AMP might be related to the overall steric effect of the methyl groups on the α-carbon attached to the amine nitrogen, which decreases the collision frequency for AMP degradation through the cyclization process to form DMOZD.…”

“…Initial identification of the AMP thermal degradation product(s) was performed by mass spectral blank subtraction of the initial undegraded AMP solutions from the sample thermally degraded at 150 °C for 72 h. The resulting mass spectrum showed a single large peak with a protonated [M + H] + accurate mass of 116.07063 m / z , corresponding to a unprotonated molecular formula of C 5 H 10 N 2 O at a mass accuracy of 0.28 ppm. Based on previous thermal degradation experiments with MEA, where the cyclized MEA-carbamate, oxazolidin-2-one (OZD) is a primary thermal degradation product, the most likely chemical structure with this molecular weight would be cyclized AMP carbamate, DMOZD …”

Enhancements in mass transfer for carbon capture solvents part I: Homogeneous catalyst

“…In order to examine the stability of 1 toward degradation by NOx and SOx, pH drop experiments were conducted in both capture solvents in the presence of 1000 ppm NOx, and SOx derived products. These concentrations are considered to be in the operational range of an amine-based capture process, 58 and no decrease in activity was observed (Figure 11a). Experiments were also conducted where solutions containing 1 were exposed to a large excess NOx gas, generated from overall energy penalty upon addition of 1 was determined using a bench-scale integrated CO2 capture unit.…”

Thermal Degradation Comparison of Amino Acid Salts, Alkanolamines and Diamines in CO2 Capture

“…Detail operations have been previously described in publication [13]. Nitrogen was bubbled through the sample tubes prior to closure to minimize the oxygen in the samples.…”