Kinetic modelling of the hydrolysis of carbonyl sulfide catalyzed by either titania or alumina

The reaction rates for the hydrolysis of COS on both alumina (Kaiser 201) and titania (CRS 31) were measured from 270 to 330°C using a laboratory Berty reactor over ranges of water concentration, 2-12 mol %, and COS concentrations, 0.5-2 mol %. Four mechanism-related model functions were tested in the search for the best fitting function by using nonlinear regression techniques. The results indicate that an Eley-Rideal model provides the best fitting rate function for the hydrolysis of COS for both alumina and titania, even though their catalytic activities are different. The Bates and Watt's (1980) curvature measure along with simulation studies were used in the nonlinear regression search for the best values of the model parameters. The kinetic parameters obtained confirm that CRS 31 appears to be the better of the two catalysts for COS hydrolysis. The adsorption of water vapor significantly retards the hydrolysis rate, more so for Kaiser 201.