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

Abstract

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 x 10(-10) mol/cm(2) s Pa, even higher than that of 30 wt% MEA (3.30 x 10(-10) mol/cm(2) 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).