Effects Of Modified TiO₂ On De-mercury And Denitrification Efficiency In The Combustion With Biomass And Coal

The modified TiO₂ was prepared by microwave-assisted sol-gel method and the experiment of denitrification and demercuration of coal and biomass co-combustion was carried out in the tubular furnace.The effects of the types of coal,the types of biomass,the blending ratio of coal and biomass,the types of Ca-based additives,the Ca/S ratio,the preparation conditions of catalysts,the types of catalysts,the amount of catalysts,combustion temperature on denitrification efficiency was studied.The effects of the types of biomass ? the Ca/S ratio and combustion temperature on the removal efficiency of Hg⁰ were investigated.The catalyst TiO₂ was characterized by XRD,BET,SEM,EDS and XPS.In the last part of this paper,the coal char denitrification experiment was carried out,and the composition of coal ash was analyzed.The optimal preparation conditions of the catalyst were obtained: The optimal doping amount of Zr and CTAB 1% and 2%,the calcination temperature of Zr-CTAB-TiO₂ 400?,the microwave power 600 W.The denitrification efficiency reached the highest 72.27% at the combustion of 850? when Shanxi coal and Hebei corn cob to 6:4 mixing combustion,adding calcium acetate?Ca/S=2.3?,Zr-CTAB-TiO₂?Zr 1%,CTAB 2%,400??and dosage 8%.It increased by 35.94%without adding TiO₂ and increased by 33.69% after adding pure TiO₂.The demercuration efficiency reached the highest 35.84% at the combustion of 850?when Shanxi coal and Hebei corn cob to 6:4 mixing combustion,adding calcium bromide?Ca/S=2.3?.It increased by 6.23% without adding TiO₂ and increased by6.08% after adding pure TiO₂.It can be concluded that the biomass corn cob and the catalyst Zr-CTAB-TiO₂ can simultaneously realize the denitrification and demercuration in the same experimental setup under the same experimental conditions.The characterization of catalyst showed that surfactant CTAB doping increases the specific surface area,oxygen vacancies of TiO₂,improved TiO₂ surface oxidation reduction ability.At the same time,the addition of CTAB enhanced the ability of the TiO₂ surface adsorption of ammonia.The characterization results consistent with the data obtained in the experiment.The catalyst Zr-CTAB-TiO₂ accelerates the cracking reaction of coal itself,the coal volatile release amount increased,thereby increasing the char surface area,porous coal to coal combustion generated NOx diffused into the inner surface of the coke reaction,improve coal on NO heterogeneous reduction of chemical adsorption effect and char on Hg⁰.The catalyst Zr-CTAB-TiO₂ can achieve simultaneous desulfurization and denitrification,and can reduce the ash slagging rate,improve the operation efficiency of the boiler.