Investigation Of Performance Over Iron-based SCR Denitration Catalyst At Low-medium Temperature

In recent years, with the rapid development of industrialization in China, atmospheric pollution caused by the burning of fossil fuels has being more and more serious. NOx is one of the main atmospheric pollutants, which bring huge harm to human body and environment, it is one of the urgent problems at home and abroad to be solved. There are many methods controlling NOx emission,one of the most widely used is selective catalytic reduction(SCR), it has advantages of high denitration efficiency and N2 selectivity.At present, there exist some problems in the commercial catalyst, the price is expensive, narrow active temperature window, and abandoned catalyst will lead to secondary pollution. So, it has very important significance to develop environmental friendly catalyst, low temperature, high efficiency and cheap. Iron oxide, has received the attention of scholars both at home and abroad, because it has advantages of environmentally friendly, low prices,and strong reducibility. This paper focuses on the preparation and characterization of denitration catalyst based on Fe.First, a series of experiments were conducted to research denitration catalyst based on Fe, including the preparation method and the content of Ce O2. The catalysts were characterized with XRD, XPS, H2-TPR, BET and UV-Vis DRS, and the denitration activity and the oxidation rate of NH3 over catalysts was evaluated. Then, the basic properties of multiple metal oxide were characterized by the means of XRD, XPS, XRF, BET, and the basic denitration activity of multiple metal oxide was studied. Non supported catalysts was prepared with XO, Ti O2, Fe2O3 as base material, carrier and active constituent respectively. The effects of XO and different assistant on the SCR catalytic activity was investigated.The research on non supported Fe2O3 catalysts shows that The catalyst prepared by template method has has larger specific surface area, stronger oxidation and acid than the catalyst prepared by coprecipitation method, increased the denitration activity. The former than the latter has a wider temperature range of activity and higer denitration activity at high temperature.The characterization of the different content of Ce O2 catalyst indicate that the catalysts with 2wt.% and 4wt.% content of Ce O2 possess higher catalytic activity and lower oxidation rate of ammonia, and, this was mainly caused by the change of oxidation of iron species.The basic nature of the multiple metal oxide was studied. The results show that there are many elements in the multiple metal oxide, such as Fe, Si, Al,etc. and Si, Na, Al, V element enriched on the surface of the particles. Multiple metal oxide with low specific surface area and denitration, was not suitable for denitration catalyst or active component.The supported catalyst was prepared with XO, Ti O2, Fe2O3 as base material, carrier and active constituent respectively, in order to studied the effect of base material on the catalyst. The experimental results show that the addition of multiple metal oxide lead to the surface area reduced and oxidation enhanced of catalysts. The catalyst has the better activity, the activity of 250 ℃-350 ℃ were greater than 90%, but the active temperature window was narrow.Use of Ce O2, Mo O3, WO3 to doped catalysts, the results show that the doped of Ce O2, Mo O3, WO3 made the surface area increased, which is helpful to the adsorption of ammonia, promoted the SCR reaction.The denitrification activity rised in the overall of catalyst doped by Ce O2 and the best active temperature window width; The denitrification activity reduced in the low temperature and rised in high temperature of catalyst doped by Mo O3 or WO3, the best active temperature window width and shifted to higher temperature.