Catalytic Oxidation of Low Concentration SO₂ over V₂O₅-K₂SO₄ Catalyst

Abstract

Present work was done in order to get some informations on the mechanism of the catalytic Oxidation of SO₂, especially in it lower concentrations (0.1-1.5%), and to design the equipment for the removal of SO₂ from flue gases.
The initial oxidation rate was measured at a reaction temperature of 400-500° C, at SO₂ concentration of 0.1-4.5% and O^2- concentration of 0.4-5%. The experiments were carried out under the conditions where diffusion rate had no significant effect on the reaction rate. Experimental results are shown:
a) The oxidation rate increased with increasing partial pressure of oxygen (Fig.4, 5, 6).
b) The oxidation rate arrived at a certain value when the partial pressure of SO₂ increased, but further increase in partical pressure reduced the oxidation rate (Fig.7, 8, 9).
c) The position of the peak in the curve of oxidation. rate (Vs) vs. partial pressure of SO₂ (P5O^2-) was not influenced by partial pressure of oxygen (PO^2-), but changed with reaction temperature (Fig.7, 8, 9). Thus it is evident that the overall reaction rate was controlled by the reaction between the adsorbed SO₂ and adsorbed oxygen on the catalyst. The oxidation rate was expressed by the following equation.
Vs=kPo2Pso2/(1+KIPso2)2
The valence change between the tetravalent and the pentavalent state of vanadium in the mixture, V205-K2SO₄, was masured under the same conditions as steady state of the reaction, and the results showed that the value of V6+/(V5+ V4+) was not influenced by PO^2- but by P5O^2-.