Reaction Mechanism and Kinetics of Aqueous Solutions of 2-Amino -2 Methyl-1,3- Propanediol and Carbonyl Sulphide

Aqueous solutions of amines are often used to remove CO2, H2S and COS from a large number of industrial gas streams. There are several different processes, each suiting a certain application. A recent advance in gas treating technology is the application of sterically hindered amines, which offer capacity advantages for CO2 over commercial amines such as monoethanolamine (MEA) (Sartori and Savage). All amines react with H2S instantaneously, while the reaction rates with CO2 and COS are both finite. In the case of sterically hindered amines, where the amino group is attached to a tertiary carbon atom, the reaction rates with CO2 and COS are often reduced significantly due to steric hindrance. This may, however, be a desired property for CO2 if a certain calculated amount of selective removal is planned. 2-amino-2-methyl-1-propanol (AMP) is a commercially available primary amine, the sterically hindered form of MEA. Another sterically hindered amine which might be of interest in industry is 2-amino-2-methyl-1,3-propanediol (AMPD). AMPD has a similar chemical structure to AMP where one of the -H is replaced by -OH. Recently, Bouhamra et al. studied the kinetics of reaction between aqueous AMPD and CO2 and found that it follows, zwitterion intermediate mechanism. In selective removal, the reaction rate of the AMPD-COS system is also of interest, but such data are not available in the literature. The kinetics of other amines have been studied by Alper et ∗On leave from Chemical Engineering Department, Hacettepe University, Beytepe