Sulfur dioxide oxidation in slurries of activated carbon. Part I. Kinetics

Dynamic adsorption and reaction studies were made for the catalytic oxidation of sulfur dioxide in aqueous slurries of activated carbon at room temperature and atmospheric pressure. For the small particles ( d p = 0.03 mm) of carbon used, mass transfer resistances were of minor importance so that the data could be analyzed in terms of the kinetics of the chemical reaction. Quantitative evaluation of mass transfer effects, including intraparticle diffusion, is presented in Part II. The rate was first order in oxygen concentration in the liquid and zero order with respect to SO 2 . The rate decreased with increasing H 2 SO 4 concentration in the liquid. This was explained by the decrease in solubility of oxygen in the solution rather than by a change in reaction rate constant. The adsorption and rate data together suggest that the controlling step in the mechanism is the adsorption of oxygen on active sites of the carbon surface. The low concentration of oxygen in water (due to its low solubility) reduces its rate of adsorption.