Amine solutions are still at the heart of the most mature technology for post-combustion CO2 capture. Serious concerns exist however about the involved costs especially in the release process and several problems must be solved before their application can be extended to large scale. The need for both solvent and process optimization has also promoted fundamental research – based both on experimental and computational methods - aimed at a deeper understanding of the key reactions of CO2 in solution. Using DFT-based molecular dynamics aided by metadynamics, we have studied the capture and release of CO2 in selected aqueous amines: ammonia, monoethanolamine (MEA), 2-amino-2-methyl-1,3-propanediol (AMPD), 2-amino-2-methyl-1-propanol (AMP) and benzylamine (BZA). Comparison of the different behavior of the selected amines has led us to clarify the main factors characterizing CO2 capture via either carbamate or bicarbonate formation. The carbamate-zwitterion was found to be relevant not only for the formation of the carbamate – as generally agreed - but also for that of carbamic acid and for the release of CO2. The role of water—previously strongly underestimated in computational studies —was established as essential in facilitating the development of all the relevant reactions.

Reaction dynamics of CO2 in amine solutions from DFT-based simulations

253rd National Meeting (2017)

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