Absorption of carbon dioxide by the mixed aqueous absorbents using 2-methylpiperidine as a promoter

Mixed solvents based on tertiary amine and sterically hindered amine were tested for CO2 capture performance with 2-methylpiperidine (2MPD) as an additive to improve the mass transfer rate of those absorbents, which have slow reaction rate with CO2. The absorbents are triethanolamime (TEA), N-methyldiethanolamine (MDEA), and 2-amino-2-methylpropan-1-ol (AMP). A wetted wall column (WWC) was used to measure the mass transfer rate of the mixed solvents and the CO2 loading was evaluated by vapor–liquid equilibrium (VLE) measurement. The mass transfer rate of both tertiary amines (TEA, MDEA) and sterically hindered amine (AMP) increased greatly as 2MPD was added. The AMP/2MPD containing 10 wt% of 2MPD showed the highest mass transfer rate of 3.92×10−10 mol/cm2 s Pa, even higher than that of 30 wt% MEA (3.30×10−10 mol/cm2 s Pa). The CO2 loading capacities of the mixed solvents were excellent compared to MEA. The absorption capacities of the AMP/2MPD and MDEA/2MPD were about 0.8 to 0.9, 1.7 times better than that of MEA (about 0.5).

► Enhance the absorption performance with 2-methylpiperidine.
► Wetted wall column used to measure CO2 mass transfer rate.
► Loading capacity measured through vapor–liquid equilibrium.
► Enhance the mass tansfer rate and loading capacity.