Mn-catalyzed oxidation kinetics of calcium sulfite in wet FGD process

In order to study Mn-catalyzed oxidation kinetics of calcium sulfite under typical wet flue gas desulfurization (FGD) conditions, a laboratory-scale mechanically stirred tank reactor was used with continuous feeding of both gas and liquid phase. The test results show the Mn-catalyzed oxidation kinetics follows a parallel reaction mechanism and the Mn-catalyzed reaction rate has a 1/2-order dependence on the concentration of Mn²⁺. while CaSO₃ load is lower with the catalysis of Mn²⁺, the overall rate is only dependent on the concentration of Mn²⁺, and is independent of solid sulfite dissolution, while pH is 5.0 and CaSO₃ load is more than 50 mol/m³, the Mn²⁺ catalysis does not increase the oxidation rate, while pH is 5.5 and CaSO₃ load is more than 55 mol/m with the 1 mM Mn²⁺ catalysis, the oxidation rate is limited by oxygen gas-liquid diffusion while uncatalyzed oxidation rate is limited by solid sulfite solubility.