How do amines react with flue gases to absorb CO₂?
In addition to the reaction in permeakra's answer, some amines may react with $\ce{CO2}$ in absence of water also. This type of reaction is a Lewis acid-base reaction forming a zwitterionic complex: $\ce{R3N + CO2 -&gt; R3NCO2}$.

 

MDEA adds some stability to this complex. The alcohol groups can stabilize the carboxylate group through hydrogen bonding.