Kinetics of removal of carbonyl sulfide by aqueous monoethanolamine

The kinetics of the reaction between carbonyl sulfide and aqueous monoethan olamine (MEA) were studied over a range in temperature (298-348 Kj and amin e concentrations (5-20 wt %) using a wetted-sphere absorber. The experiment al data were interpreted using a zwitterion mechanism. The key physicochemi cal properties needed to interpret the data are the solubility and diffusiv ity of COS in the aqueous amine solution. These properties were estimated u sing the N2O analogy method. Experimental values of N2O solubility were cor related using an extended scaled-particle model, and the measured N2O diffu sion coefficients were correlated using a modified Stokes-Einstein equation . Solution densities and viscosities were also measured and: correlated in this work. On the basis of the zwitterion mechanism whose rate-limiting ste p was the deprotonation of a zwitterion, the Arrhenius relationship between the third-order rate constant and the temperature was well correlated with an absolute mean deviation of 0.3%. It could be thus concluded that the ov erall reaction rate was first-order in the COS concentration and second-ord er in the MEA concentration.