Study On Reduction Of Nitric Oxide By Calcium-Containing Carbonaceous Materials

Since 1990s, NO_x emissions from industry departments china are huge, and it leads to environmental pollutions and health hazards. Traditional NO_x control technologies, such as selective catalytic reduction, are used extensively, but they suffer from many shortages and limitations. In these sense, the catalytic reduction technologies based on carbonaceous materials have been intensively investigated in recent years, in which carbon is consumed as reducing agent towards NO rather than as sorbent or catalyst.In this thesis, CaO-loaded activated carbon (Ca/C) was prepared by impregnation, catalytic effect of CaO on C—NO reaction was studied, and effect of temperature, oxygen concentration, and metal load on C—NO reaction was discussed, and kinetics of Ca/C—NO were investigated. Moreover, coke containing calcium was used to reduce high concentration NO creatively, and effect of coke load, particle size and others parameters on coke—NO reaction was studied. The results show:1. In the absence or presence of oxygen, C—NO reaction was catalyzed by CaO, and starting reaction temperature was decreased by 200 ℃ ～ 300 ℃, and NO_x destruction rate was enhanced.2. In the presence of oxygen, temperature, oxygen concentration, NO concentration and metal load had great effect on Ca/C—NO reaction. Increase of temperature and oxygen concentration led to enhance of reactivity and decrease of reaction selectivity. In our experiments, reaction selectivity in 600℃ was only 72 percent of that in 300℃, and selectivity in 0.25% oxygen concentration was about seven times more than that in 5 % oxygen concentration. At the same time, selectivity was enhanced with increase of NO concentration, and Content of calcium on activated carbon had great effect on reactivity, and 3% was optimum.3. In the absence of oxygen, when content of calcium was 3%, the activation energy of Ca/C—NO reaction was 32.13 kJ/mol which was only 36 percent of that of C—NO reaction.4. The starting reaction temperature of coke—NO was lower than 300℃, and reactivity and selectivity were benefit from increasing of temperature, in our experiments, selectivity reached 102mg/g in 850℃. Coke—NO reaction was more sensitive to temperature when temperature was higher than 520℃.5. In the presence of oxygen, particle size and oxygen concentration had great effect on coke—NO reaction as well as coke load, and the optimum was 0.71～0.85 centimeter and 1 % respectively. Reactivity and selectivity were benefit from increase of temperature and NO concentration.