Effect of alkanol chain length of primary alkanolamines and alkyl chain length of secondary and tertiary alkanolamines on their CO2 capture activities

Prediction of Alkanolamine pKa Values by Combined Molecular Dynamics Free Energy Simulations and ab Initio Calculations

“…Similarly, based on the AM1-BCC predictions, the pK a values of EAE (9.79), MPAE(9.66), IBAE(9.62), TBAE (9.59), IPAE(9.33) are higher than that of MEA(9.00), further indicating that the addition of alkyl chains to the nitrogen atom of MEA increases the pK a value. This trend was also observed in the recent experimental study of Narku-Tetteh et al, 71 who found that the longer alkyl chain lengths of secondary alkanolamines resulted in higher equilibrium CO 2 loading and pK a values.…”

Experimental Studies on the Effect of Tertiary Amine Promoters in Aqueous Monoethanolamine (MEA) Solutions on the Absorption/Stripping Performances in Post-combustion CO2 Capture

“…Furthermore, the effect of the position and number of side chains (i.e., methyl group) of MEA/1DMA2P was compared with that of MEA/DMEA. It can be concluded that the addition of methyl at the β carbon atom can significantly enhance both the CO 2 solubility and the absorption rate . However, both the addition of methyl at the α carbon atom and the increase of methyl group number can decrease the CO 2 absorption rate and CO 2 equilibrium solubility, which can be seen by comparing the MEA/2DMA2M1P and MEA/DMEA.…”

“…This can be attributed to the substitution of the methyl group in DMEA with the ethyl group in DEEA, the latter of which is a bigger electron-donating group, thus enhancing its activity compared with methyl group. Thus, it can be concluded that tertiary amines with a hydroxyl group at the γ carbon atom have better absorption performance than tertiary amines with a hydroxyl group at the β carbon atom . In addition, it indicates the chain length has an important effect on the absorption performance, and the longer chain length results in an increase reaction rate .…”

“…It can be concluded that the addition of methyl at the β carbon atom can significantly enhance both the CO 2 solubility and the absorption rate. 49 However, both the addition of methyl at the α carbon atom and the increase of methyl group number can decrease the CO 2 absorption rate and CO 2 equilibrium solubility, which can be seen by comparing the MEA/2DMA2M1P and MEA/DMEA. This is due to more obvious occurrence of steric hindrance by adding the methyl group at the α carbon atom than at that of the β carbon atom, leading to a decrease of the activity of the nitrogen atom.…”

“…Thus, it can be concluded that tertiary amines with a hydroxyl group at the γ carbon atom have better absorption performance than tertiary amines with a hydroxyl group at the β carbon atom. 49 In addition, it indicates the chain length has an important effect on the absorption performance, and the longer chain length results in an increase reaction rate. 50 This phenomenon was also found by evaluating the CO 2 equilibrium solubility of MEA/1DMA2P and MEA/1DEA2P.…”