| NOx as notorious atmosphere pollutants can bring about environmentally hazardous,such as acid rain and photochemical smog. Evenly, they play a crucial role in destroying ozone layer that can have an effect on human health. Worst of all, some people are not conscious of the seriousness of the problem. Recently, the technology of SCR (Selective Catalytic Reduction) is widely applied for denitrification. Undoubtedly, selecting suitable catalysts with excellent performance is the key in the whole procedure. And recently catalysts with excellent performance at low temperature is still prevalent in research field.In this paper, we mainly introduce various catalysts in the treatment of nitrogen oxides(NOx) under low temperature. In the meantime,we design and optimize an approach to synthesized Mn-Ce-V-W/TiO2 catalysts.In this paper, our first task is to improve constituent content that rather high activated elements overloaded on Mn-Ce-V-W/TiO2 catalysts. According to reducing activated elements content singly or systematically, we investigated how various constituent content influence catalysts performance, such as denitrification efficiency, surface area (SBET) and its construction. The experimental data draw a conclusion that the best constituent content loaded on the catalysts is 0.225. Also, collaboration of catalysts with certain constituent content can vitally influence its performance under low temperature. It showed that elements overloaded on the surface of catalysts that systematically lowing content at original ratio exhibited perfect denitrification efficiency under low temperature. Soon afterwards we improve catalysts molding technology. Just annealing the improved catalysts one time that can prevent the waste of resources can greatly enhance its denitrification efficiency. We characterized catalysts by XRD, SEM, BET, lifetime, water and sulfur resistance, and the activity for denitrification. The characterization results found that the improved molding technology can enlarge SBET Of products and have no impact on its construction, lifetime, water and sulfur resistance.We also adopted a new synthesis method (sol-gel) to improve its denitrification performance. New prepared catalysts via sol-gel method have rather high performance compared with the previous under low temperature. Also, characterization (BET, XRD,NH3-TPD) prove the series of products have larger SBET and better surface acid sites,reduction performance that is promoter for denitrification. The results is consisted with our experimental data.We also added active edement (Fe) to discuss its effect. Respectively,impregnation and sol-gel method was adopted to obtain products. By testing results it is clear that the addition of Fe can enhance denitrification performance under low temperature.Comparatively, catalysts obtained via sol-gel method are better. Also, we characterized products by XRD, SEM, BET, FTIR, H2-TPR. It found that synthesis method don not alter crystal form that can attribute to even disperse of elements. Its SBET is greatly higher than catalysts without Fe element. NH3-TPD and FTIR showed that the addition of Fe element can strengthen surface acid. And H2-TPR testing results showing reduction temperature transformed into lower that can exhibit better reduction performance. Also, the lifetime,water and sulfur resistance is better. |
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