稻壳白炭黑负载Fe_(2)O_(3)的气相芬顿反应NO预氧化

NO preoxidation by gas phase Fenton reaction with Fe_(2)O_(3) over rice husk-based silica carrier

以稻壳为硅源,采用直接煅烧法制备白炭黑,以其为载体,采用共浸渍法制备Fe_(2)O_(3)/SiO_(2)催化剂;并采用同样方法以商用二氧化硅为载体制备Fe_(2)O_(3)/C-SiO_(2)催化剂,将二者用于催化H_(2)O_(2)预氧化NO的实验。探究不同工况(负载量、催化温度、H_(2)O_(2)汽化温度、H_(2)O_(2)流量和水汽浓度)对NO预氧化的影响,并对催化剂进行表征,分析其物理化学性质对催化性能的影响。结果表明,在负载量为50%、催化温度为140℃、H_(2)O_(2)汽化温度为120℃、H_(2)O_(2)流量为2.5mL/h时,达到最佳工况,NO氧化度能达到73%;在相同实验条件下Fe_(2)O_(3)/SiO_(2)催化剂的预氧化效果要比Fe_(2)O_(3)/C-SiO_(2)催化剂高20%左右。TPR结果表明载体可以降低活性组分的还原温度,减少活性组分的团聚;催化剂的晶相结构稳定,机械强度及热稳定性良好;ESR和XPS结果显示Fe_(2)O_(3)/SiO_(2)催化剂的催化性能优于Fe_(2)O_(3)/C-SiO_(2)催化剂,能够更好地催化分解H_(2)O_(2)产生·OH。

With rice husk as silicon source,silica was firstly prepared by the direct calcination method,and then the Fe_(2)O_(3)/SiO_(2) catalyst was prepared by co-impregnation method with the silica as the carrier.As a comparison,the Fe_(2)O_(3)/C-SiO_(2) catalyst supported on commercial silica was prepared by the same method.Both catalysts were used in catalyzing H_(2)O_(2) to pre-oxidize NO.The effects of different operating conditions(loading,catalysis temperature,vaporization temperature of H_(2)O_(2),flow rate of H_(2)O_(2) and vapor concentration)on the pre-oxidation of NO were systematically investigated.In addition,the physicochemical properties of the catalysts were characterized and attempts were made to correlate them with their catalytic performance.The experimental results indicated that a NO oxidation efficiency of 73% could be achieved when the loading was 50%,catalysis temperature was 140℃,vaporization temperature of H_(2)O_(2) was 120℃,and the flow rate of H_(2)O_(2) was 2.5mL/h.Under the same experiment conditions,the NO pre-oxidation efficiency of Fe_(2)O_(3)/SiO_(2) catalyst was about 20% higher than that of Fe_(2)O_(3)/C-SiO_(2) catalyst.TPR result showed that the carrier could lower the reduction temperature of active components and further reduce their agglomeration.The catalyst has a stable crystal structure,and good mechanical strength and thermal stability.ESR and XPS results indicated that the catalytic performance of Fe_(2)O_(3)/SiO_(2) catalyst was better than that of Fe_(2)O_(3)/C-SiO_(2) catalyst,which better catalyzed the decomposition of H_(2)O_(2) to produce·OH.