Understanding amine solvent degradation and its control

Supervisors:  Prof. H. Knuutila, Dr. V. Buvik

Project Description:

Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities, and the development and implementation of technologies for CO2 emission reduction is of great importance. Of the various methods to separate CO2 from industrial gases, absorption-based CO2 capture using aqueous alkanolamine solutions has reached the commercial stage.

One of the remaining challenges is solvent degradation and equipment corrosion. By definition, degradation is the irreversible transformation of an absorbent solution into other compounds. These byproducts can cause problems like equipment corrosion, amine loss, fouling, foaming and reduction of CO2 absorption capacity. Also, some of the degradation products can be toxic. Corrosion and degradation are closely tied since some of the degradation compounds formed are corrosive agents causing equipment corrosion in the absorption plant, which leads to additional costs. Furthermore, corrosion often increases degradation as dissolved metals can enhance degradation reactions. Over time, corrosion can cause unscheduled downtime, reduce process efficiency and solvent and equipment life.

This PhD work focuses on improving the understanding of parameters affecting corrosion and degradation of different solvent systems by addressing two topics: 

1) Although significant progress has been made in understanding degradation and corrosion in CO2 Capture Plants, further theoretical and experimental research must be done. This work addresses this by investigating the corrosion rates and degradation mechanisms of different amines and the effect of process parameters on degradation and corrosion.  

2) Additives could be used to inhibit degradation and corrosion in absorption-based post-combustion capture plants. As degradation and corrosion are closely tied, additives should inhibit both degradation and corrosion. More detailed insights into degradation and corrosion allow the development of mitigation technologies, like inhibitors. This work will test different non-toxic corrosion and degradation inhibitors at process-relevant conditions using different solvents to gain insight into the opportunities and challenges.

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