Page 57 - Gas Purification 5E

dlkanolarnines for Hydrogen Sulfide and Carbon Dioxide Removal 47

14 1 I I I I I
APPROXIMATELY 2N SOWTION, TEMPERATURE=25.C, 77.F

MOLES ACID GAS/ MOLE AMINE
Figure 2-5. Titration curves showing pH during neutralization of ethanolamine and KOH
solutions with COP.

D
TEMPERATURE, OF:
Figure 2-6. pH values of aqueous mono- and diethanolamine solutions (technical grade).

HIS and C02 absorption into aqueous solutions of MDEA has been studied by a number of
investigators (Savage et al., 1981; Ouwerkerk, 1978; Blanc and Else, 1981). Savage et al.
(1981) found that although the rate of H2S absorption could be thermodynamically predicted,
the rate of C02 absorption, measured experimentally, appreciably exceeded that predicted on
the basis of thermodynamic considerations, and they concluded that MDEA apparently acts
as a base catalyst for hydration of CO?. More recently, investigators have found that the rate
of CO, absorption in MDEA can be significantly increased by the addition of relatively low