Effect of Side Chain Structure and Number of Hydroxyl Groups of Primary, Secondary and Tertiary Amines on their Post-Combustion CO2 Capture Performance

Abstract

The effect of the side chain structure and the number of hydroxyl groups in primary, secondary and tertiary amines on kinetics of CO2 absorption (40oC, 15% CO2 feed gas) and desorption (at 90oC), equilibrium loading, heat duty, cyclic capacity, heat of absorption and pKa were investigated. The results showed that, compared with their straight-chain analogues, steric hindrance in branched-chain alkanolamines resulted in much higher solubilities and lower initial absorption rates. Steric hindrance in tertiary amines increased the desorption rate but lowered the heat duty. More hydroxyl groups attached to nitrogen group resulted in a lower absorption rate and amine basicity.