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). While COS is not itself corrosive, the hydrolysis product H2S is corrosive, especially in the presence of water. In this paper,we summarize the results from studies that address the issue of COS hydrolysis in propane, thought to be a major problem in the liquefied petroleum gasindustry. A series of kinetics measurements was performed on the hydrolysis reaction in propane. In these measurements, mixtures of COS and propanewere prepared and placed in a reaction vessel, and then a controlled quantity of water was added. Chromatographic monitoring of the decrease in COS and!the appearance of H2S in the vapor phase as a function of time allowed measurement of the reaction rate. The hydrolysis rate was measured for 500 and1000 ppm mixtures of COS in propane at 38, 65, and 85 C COS hydrolysis was not observed in propane at 16 C. In addition, rate constants weremeasured for the hydrolysis reaction catalyzed by potassium hydroxide and alkanolamines. The rate of hydrolysis of COS in the aqueous propane system isseveral orders of magnitude slower than in pure water.
Citation: Industrial and Engineering Chemistry Research
Issue: No. 5
Pub Type: Journals
alkanolamines, carbonyl sulfide, COS, hydrolysis kinetics, liquefied petroleum gas, LPG, secondary-amines