Reaction chemistry of CO₂ absorption

The removal of CO₂ is required in many applications. Eastman AdapT solvents rely on the chemistry of different amine-CO₂ reactions to optimize the performance for each application.

Tertiary amines, such as MDEA, form a bicarbonate with CO₂, which is slowly formed in the amine solution. This is illustrated in the following reaction scheme:

 

Non-tertiary amines can react much faster with CO₂ through formation of a carbamate. The free proton formed in this reaction may protonate a second amine, which is also a fast step, but reduces the absorption capacity. This is illustrated in the following reaction scheme:

 

Through selection of the type and concentration of the different amines, the CO₂ removal rate and absorption capacity can be adapted. In addition to CO₂ removal efficiency, system corrosion and operational limitations can also be important factors in solvent selection.