Preparation and SO capture kinetics of a DeSO coating for the desulfurization of exhaust emission.

Sulfur dioxide (SO) is an extremely harmful pollutant in diesel engine exhaust fumes, which must be controlled and removed effectively. In order to better integrate desulfurization materials into diesel exhaust systems, a new desulfurization powder coating (DeSO coating) was prepared. The SO capture performance and kinetics of the DeSO coating were subsequently studied. This study used a fixed-bed reactor to test the DeSO coating SO capture performance and conduct kinetic analysis at various temperatures and gas flows. The analysis obtained the kinetic parameters of the activation energy and Arrhenius constant, with the derived rate control equations, under isothermal conditions. The DeSO coating and filter which were prepared using metal oxide powders, SiO colloidal sol, and additives, exhibited an enhanced SO capture performance. In this experiment, an MnO/SiO/LiOH coating had the best SO removal rate and capture capacity at 400 °C. Under a reaction space velocity of 10700 h, the MnO/SiO/LiOH coating SO removal rate was 100% within the first hour of reaction. Under a reaction space velocity of 32000 h, the MnO/SiO/LiOH coating SO capture capacity was 132.7 mg/g during the second hour of reaction. The SO capture conversion rate of the DeSO coating and filter follows the second-order kinetic mechanism model. For the MnO/SiO/LiOH coating, the Arrhenius equation gives an activation energy of 4952 J/mol and the Arrhenius natural logarithmic constant is 8.969 s. For the MnO/SiO/LiOH filter, the activation energy of the rate constant is 214 J/mol, and the Arrhenius natural logarithmic constant is 3.744 s. Therefore, the desulfurization coating is an effective way to remove SO pollutants from diesel exhaust gases.