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Kinetics of Carbonyl Sulfide Hydrolysis. 2. Effect of n-Alkanes in Mixtures of Water Plus Hydrocarbon



W C. Andersen, Thomas J. Bruno


Carbonyl sulfide (COS), which occurs as an impurity in commercial sources of propane, can hydrolyze in the presence of water to form hydrogen sulfide(H2S) and carbon dioxide (CO2). Whereas COS is not itself corrosive, the hydrolysis product H2S is corrosive, especially in the presence of water. Thishydrolysis is thought to be a major problem in the liquefied petroleum gas industry. In this paper, we summarize the results from studies that address theissue of COS hydrolysis in the presence of a water and hydrocarbon system. A series of kinetics measurements was performed on the hydrolysis reaction inmethane, ethane, propane, n-butane, and n-hexane at 85 C. In these measurements, mixtures of COS and n-alkane were prepared and placed in a reaction vessel, and a controlled quantity of water was added to the vessel at time zero. Chromatographic monitoring of the decrease in COS and the appearance ofH2S in the vapor phase as a function of time allowed calculation of the reaction rate. The hydrolysis rate for the aqueous hydrocarbon system was found tobe several orders of magnitude slower than what has been previously reported for pure water. Furthermore, we found the rate of COS hydrolysis to beproportional to the binary interaction diffusion coefficient, DI 2, for alkanes in water. This suggests that the diffusion of larger organic molecules into theaqueous phase impedes the ability of COS to react with water.
Industrial and Engineering Chemistry Research
No. 5


binary diffusion coefficient, carbonyl sulfide, COS, hydrolysis kinetics, liquefied petroleum gas, n-alkanes, secondary-amines


Andersen, W. and Bruno, T. (2003), Kinetics of Carbonyl Sulfide Hydrolysis. 2. Effect of n-Alkanes in Mixtures of Water Plus Hydrocarbon, Industrial and Engineering Chemistry Research (Accessed April 25, 2024)
Created March 1, 2003, Updated February 17, 2017