Study Of Novel Mn-based Catalyst For Selective Catalytic Reduction Of NO_x At Low-temperature

The low-temperature(60～180℃) catalyst could locate the SCR unit upstream of the electrostatic precipitator, which decreased the operation cost and prolonged the catalyst's life greatly. This disposal avoided flue gas reheating which was necessary for the commercial catalyst V2O5-(WO3)/TiO2 whose operating temperature was more than 350℃,and decreased the dust poison on the catalyst. On the other hand, the low-temperature SCR technology could match the system in which energy saver, air-preheater and boiler were incorporated in our country. For the reasons above, there have been strong interests to develop highly active and highly mithridatism catalysts for low-temperature SCR. Reviewing the study results of this area in and abroad, Mn-based catalysts took on better low-temperature SCR activity, hold good empoldering potential. For the traditional SCR technology, recontamination of reductant NH3 is another serious problem, which resulted from the leak of excessive NH3.Investigators had paid a lot attention to this problem. Seeking new, economic and effective reducing agents such as hydrocarbon and activated carbon to replace NH3 was their main study direction. Also some researches showed that NH4+-zeolite possessed highly reductive activity for NOx, and that it was capable to solve the NH3-recontamination problem.Therefore, this work was carried out as following aspects: (1)To satisfy the need of industry application, the catalyst Mn-Ce/TiO2 which was the outcome of prophase study and had excellent performance at low temperature was modified. (2)Mn-base NH4+-zeolite catalyst was prepared. The catalyst hold good low temperature SCR activity and the capacity to reduce recontamination of NH3.The research of Mn-Ce/TiO2 modifying mainly included two aspects: molding and addictives addition. The molding experiments showed that molding Mn-Ce/TiO2, which was gotten by molding the carrier TiO2 with 25% phosphor and then dipping the active components, could attain 90% NOx conversion under the condition that the reaction temperature was 180℃. At the same time, it had strong mechanical strength and was suitable for industry application.Adding addictives to Mn-Ce/TiO2 aimed for enhancing its activity and poison-resistance-capability at low temperature. Results showed that addictive Fe,V or Cu could advance Mn-Ce/TiO2's low temperature activity,when the temperature was just 120℃, NOx could almost be 100% converted to N2 over the modified catalysts Mn-M-Ce/TiO2. V could improve Mn-Ce/TiO2's SO2-resistance-capability. On the contrary, Fe or Cu decreased its inherent SO2-resistance-capability. Addictive Fe could...