关键词: 脱硝, 活性炭, 吸附, 选择性催化还原

Abstract: Nitrogen oxides (NOx) emission of sintering flue gas accounts for more than half of the total NOx emission in the steel industry. With the increasingly stringent environmental regulations, the existed and new sintering machines equipped only with the denitration equipment of flue gas can meet the requirements of NOx emission regulations. Activated carbon has an abundant microporous structure, large specific surface area, and strong absorption capacity. SO2, NOx, dust, and other harmful gases of flue gas can be removed simultaneously by activated carbon at low temperature. Therefore, denitration of sintering flue gas on activated carbon has significant technical characteristics and advantages at low temperatures. However, the poor sulfur and water resistance of activated carbon limits its wide utilization in the denitration of low-temperature flue gas. The denitration mechanism of low-temperature flue gas on activated carbon was reviewed in this work, and three denitration mechanisms were described in detail, namely physical adsorption, chemical adsorption and selective catalytic reduction (SCR) reactions. The oxidation as a result of the presence of oxygen in flue gas can effectively improve the denitration efficiency of flue gas on activated carbon. However, the competitive adsorption of SO2, H2O, and NO in flue gas can reduce the denitration performance of activated carbon. The inhibition and influence of SO2 and H2O on the denitration of low-temperature flue gas over activated carbon was also discussed. Chemical modification of activated carbon loading transition metal oxides and rare earth metal oxides and their effect on the activity of activated carbon were described. The mechanism of activity improvement of activated carbon loading transition metal oxides and rare earth metal oxides was also reviewed. The loading of multi-metals oxides on activated carbon and their synergistic effects on performance improvement of activated carbon were also introduced. Finally, the research direction and the industrial application of low-temperature denitration technology of sintered flue gas on activated carbon were prospected.

Key words: Denitration, activated carbon, absorption, selective catalytic reduction