Study on the mechanism of desulfurization and denitrification catalyzed by TiO2 in the combustion with biomass and coal

Abstract

The effects of Ca/S molar ratio, catalyst type, catalyst dosage, temperature on desulfurization and denitrification efficiency were investigated in the coal-powder combustion with corn cobs as biomass. The thermal characteristics of Shanxi coal and corn cob blends with V-TiO2 were evaluated by thermogravimetric analyzer. The catalytic mechanisms of V-TiO2 on combustion, desulfurization and denitrification were discussed, suggesting that the mechanisms are in good agreement with the experimental data. The results show that the control parameters of the ideal desulfurization and denitrification efficiency should follow that the dosage of V-TiO2 catalyst is 8% with a Ca/S ratio of 2.3 at a treatment temperature 850 °C. Meanwhile, the combustion efficiency could be effectively improved with the mixture of corn cob and V-TiO2. The thermal characteristics of coal char and corn cob char blends with V-TiO2 were evaluated using thermogravimetric analysis and derivative thermogravimetry methods to discuss the heterogeneous NO reduction mechanisms. The results show that the biomass chars were more active than coal chars in reducing NO, and the specific surface area of the chars was increased with V-TiO2, which indicates that V-TiO2 exhibits significant influence on catalytic combustion, desulfurization and denitrification.