With years of full-scale experience for pre-combustion CO2 capture, amine-based technologies are emerging as the prime contender for post-combustion CO2 capture.  However, the flue gas NOx reacts with absorbent amines in these systems to form carcinogenic nitrosamines and nitramines. The concern for the health impacts associated with the release of these contaminants has stalled the full-scale implementation of amine-based CO2 capture. Currently information is lacking regarding the reaction chemistry between NOx and amines in the presence of O2 and CO2 under CO2 capture scenarios. In this study, we systematically investigated the impacts of flue gas compositions on nitrosamine and nitramine formation. Using morpholine as a model amine, we observed that the accumulation rates of N-nitrosomorpholine (NMOR) in both the absorber solvent and the washwater increased linearly with both NO and NO2 concentrations, while the accumulation rates of N-nitromorpholine only exhibited dependence on NO2 concentration. We observed that NO played a particularly important role in NMOR accumulation in the washwater as a result of partial oxidation to NO2 by O2. Neither water vapor nor oxygen content in the flue gas has a significant impact on nitrosamine and nitramine formation. Fastest NMOR formation in the absorber was observed in the absence of CO2, but the formation rates were similar across CO2 range from 3% to 12%. Our results showed that NOx species are the most relevant to nitrosamine and nitramine formation, and that removal of both NO and NO2 prior to CO2 capture will effectively prevent nitrosamine and nitramine formation.

Influence of flue gas composition on nitrosamine and nitramine formation in amine-based post-combustion CO<sub>2</sub> capture systems

248th National Meeting (2014)

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Influence of flue gas composition on nitrosamine and nitramine formation in amine-based post-combustion CO2 capture systems

Influence of flue gas composition on nitrosamine and nitramine formation in amine-based post-combustion CO₂ capture systems