Relevance of accelerated conditions for the study of monoethanolamine degradation in post-combustion CO2 capture.

Solvent degradation represents one of the main operational drawbacks of the post-combustion
CO2 capture process. Degradation not only induces additional costs for solvent make-up, it
also impacts the process efficiency and its environmental penalty due to the emission of
various degradation products. There is still a gap of knowledge about the influence of process
operating conditions on degradation, making it currently impossible to predict the solvent
degradation rate in CO2 capture plants. Morever, the reaction mechanisms corresponding to
solvent degradation are very slow, significantly complicating its study in industrial units. In
the present work, appropriate experimental equipment and analytical methods are developed
for accelerating the degradation of monoethanolamine solvents (MEA). The relevance of
accelerated conditions is established by comparing artificially degraded solvent samples with
degraded solvent samples from industrial CO2 capture pilot plants. Two approaches are
evaluated implying either discontinuous or continuous gas feed, this latest being the most
representative of industrial degradation. The respective influences of the gas feed composition
and the gas-liquid transfer are evidenced and quantified. Finally, the present study leads to a
better understanding of solvent degradation in the CO2 capture process with MEA. More
generally, it also evidences that accelerated conditions at laboratory-scale may provide
relevant information for the study of slow phenomena taking place in large-scale industrial
processes. Further works include the development of a kinetic model for MEA solvent
degradation and the extension of this methodology to other promising solvents in order to
facilitate the operation and large-scale deployment of CO2 capture.