Influence of Dissolved Metals and Oxidative Degradation Inhibitors on the Oxidative and Thermal Degradation of Monoethanolamine in Postcombustion CO₂ Capture

Abstract

In the present work, the influence of metal ions and oxidative degradation inhibitors on the stability of monoethanolamine solvents (MEA) is studied. 2 induces additional costs and impacts the environmental balance of the CO 2 capture process as well as its efficiency. The two main degradation pathways of MEA are studied under accelerated conditions: oxidative degradation with continuous gas feed and thermal degradation in batch reactors. It is confirmed that metal ions (resulting from solvent impurities and wall leaching) enhance the oxidative degradation of MEA, while they do not impact its thermal degradation.Moreover, different oxidative degradation inhibitors are tested with varying results according to the inhibitor. It appears that at the selected concentration, radical scavengers like Inhibitor A and DMTD (2,5-dimercapto-1,3,4-thiadiazole) are more efficient than chelating agents like HEDP(1-hydroxyethylidene diphosphonic acid) at inhibiting oxidative degradation. Furthermore, attention must be paid to the influence of oxidative degradation inhibitors on the thermal degradation of MEA. Indeed, some inhibitors like DMTD, DTPA (diethylenetriaminepentaacetic acid) and DTDP (3,3′-Dithiodipropionic acid) appeared to decrease the MEA thermal stability, which cannot be accepted in industrial applications. Finally, a further drawback of DTPA is its high affinity for metal ions leading to a more corrosive solution, so that its use is not recommended for CO 2 capture applications.

Recent progress and new developments in post-combustion carbon-capture technology with amine based solvents

“…Use of chemical additives to cut down degradation can also help reduce work load of the solvent purification process. Various degradation inhibitors have been proposed over the past years (Idem et al, 2009b;Saxton and Rochelle, 2009;Lee et al, 2013;Leonard et al, 2014). Therefore, the capture process using different amines can pick and choose inhibitors appropriate for the solvents.…”

Influence of process operating conditions on solvent thermal and oxidative degradation in post-combustion CO2 capture

“…Other improvements would be to consider flue gas contaminants like SO x and NO x , to include the effect of degradation on solvent performances, and to consider degradation reactions inside additional process blocs (e.g., Voice (2013) has shown that oxidative degradation also significantly occurs in the cross heat exchanger). Similarly, the influence of degradation inhibitors as studied in Léonard et al (2014d) should also be modeled if such inhibitors are used to prevent MEA oxidative degradation.…”

Analysis of Biomass Blend Co-Firing for Post Combustion CO2 Capture

“…Heavy metals, like iron, chromium, nickel, and manganese may get into the amine solution from equipment and pipes made from stainless steel, however, copper and vanadium may be added to amine solvents as components of corrosion inhibitors [13].…”