V_2O_5-WO_3/TiO_2催化剂的制备及其烟气脱硝性能

以活性成分负载量、负载顺序和焙烧温度等关键制备参数因素进行正交实验设计制备了V_2O_5-WO_3/TiO_2催化剂,对其进行XRD和TPR表征,并在自行设计搭建的SCR烟气脱硝实验平台上评价其(300~390)℃的SCR脱硝性能。结果表明,活性成分钒和钨绝大多数以非晶态形式存在于载体表面,且具有良好的分散性;主要活性成分V_2O_5负载量越高,脱硝率越高;400℃焙烧温度可以形成催化反应所需的晶相,且维持催化剂较高的比表面积;催化剂低温活性和高温活性是由表面富集和各种成分之间相互作用共同产生的结果,活性组分与载体之间的相互作用对315℃低温脱硝活性影响明显,以先钒后钨负载顺序为宜,表面富集对390℃高温脱硝活性起主要作用,以钒钨同时负载或先钒后钨负载顺序较好;随着m(WO_3)∶m(V_2O_5)的增加,在7.5∶1处催化剂的脱硝率升至最高,随后迅速下降,WO_3负载质量分数以6%为宜。在优化条件V_2O_5负载质量分数0.8%、WO_3负载质量分数6%、先钒后钨负载和400℃焙烧温度下制备了催化剂并进行脱硝性能验证,315℃低温脱硝活性达到69.56%。

Preparation of V2O5-WO3/TiO2 catalysts and their performance for flue gas denitration

V₂O₅-WO₃/TiO₂ catalysts were prepared by orthogonal experimental design with different key preparation parameters such as active component amounts,loading sequence and calcination temperatures.The as-prepared catalysts were characterized by XRD and TPR,and their denitration performance was evaluated on the self-designed and built SCR experimental platform at (300-390) ℃.The results showed that active components of vanadium and tungsten oxides mostly with non-crystalline form were well dispersed on the support surface of the catalysts;the more the loading of main active componentsV₂O₅ was,the higher the denitration efficiency was.Calcination temperature 400 ℃ was advantageous to form the proper catalyst crystal phase required by catalytic reaction and to maintain the higher specific surface area of catalyst.The activity of the catalyst at low and high temperatures related to the surface enrichment and the interaction of components.The interaction among the active components and the support significantly influenced the low-temperature denitration activity at 315 ℃,and tungsten oxide loaded after vanadium oxide was the proper loading sequence.Surface enrichment was the main influencing factor of the high-temperature denitration activity at 390 ℃,and the optimum loading sequence was vanadium and tungsten oxides loaded at the same time or tungsten oxide loaded after vanadium oxide.With the increase ofWO₃/V₂O₅ mass ratios,denitration efficiency of the catalyst with 6wt% WO₃ first increased and reached the maximum at m(WO₃)∶m(V₂O₅)=7.5∶1,and then decreased rapidly. The optimal catalyst was prepared under the condition as follows:V₂O₅ loading 0.8wt% andWO₃ loading 6wt%,tungsten oxide loaded after vanadium oxide and calcination temperature 400 ℃,and its denitration activity reached 69.56% at 315 ℃.