SO_2对甲烷在金属铁表面还原NO的反应影响

采用卧式程序控温电加热陶瓷管反应器,在N2和模拟烟气气氛中、300~1 100℃下,研究了SO2对甲烷在金属铁及其氧化物表面还原NO反应的影响。采用XRD等手段对反应前后铁催化剂样品的组成变化进行了表征,分析了SO2在甲烷-铁脱硝反应中的作用机理。结果表明,甲烷在金属铁及氧化铁表面能够高效率地还原NO,NO还原效率不受烟气中SO2的影响。在SO2体积分数为0.01%~0.04%的N2气氛中,温度高于700℃时,金属铁上NO还原率和SO2脱除率可同时达到100%。在SO2体积分数为0.01%~0.04%的模拟烟气中,当温度高于850℃时,NO还原效率达到90%以上;温度为950℃时,NO还原效率达到98%,SO2对NO还原效率的影响可忽略。当反应温度为1 000℃时,在含0.02%SO2的模拟烟气中,甲烷的体积分数为1.13%时,持续100 h金属铁表面上的NO还原效率都能保持95%以上。

Effect of SO2 on the reduction of NO by methane over iron catalyst

The effect of SO₂ on the reduction of NO by methane over iron and iron oxides was investigated at 300~1 100 ℃ in an electrically heated ceramic tubular flow reactor in simulated flue gas and N₂ atmosphere. The iron catalyst after reaction was characterized by X-ray diffraction (XRD) and the mechanism of NO reduction by methane over iron catalyst in the presence of SO₂ was elucidated. The results demonstrated that methane is effective to reduce NO over iron and iron oxides and SO₂ in the flue gas has little influence on the reduction of NO. In N₂ atmosphere with 0.01%~0.04% SO₂, metallic iron can simultaneously eliminate almost 100% of NO and SO₂ at a temperature above 700 ℃. In the simulated flue gas with 0.01%~0.04% SO₂, the efficiencies of NO reduction at 850 ℃ and 950 ℃ are higher than 95% and 98%, respectively; the influence of SO₂ on NO reduction is insignificant. More than 95% of NO is reduced by 1.13% methane over iron at 1 000 ℃ in a durable test over 100 h in the simulated flue gas atmosphere containing 0.02% SO₂.