| With the coal as our main energy, our long-term energy structure decides our coal-burning atmospheric pollution, and coal combustion emission is the major source of NOX. Not only are we active in developing new energy and improving coal-fired technology to control NOx emission, but also we develop post-combustion control of NOx emission technology, SCR DeNOx method is one of the more mature post-combustion NOx control technologies. Catalysts hold an important position in the SCR. Recently, the key is to study DeNOx catalysts, which possess perfect efficiency at low temperature and long service life, in line with our national condition.The issue is in core of the preparation of DeNOx catalysts at low-temperature, and systematically studies SCR. Al2O3, which has large specific surface area and used as carrier, was prepared by sol-gel method in this study, prepared manganese-based catalysts by impregnation and CeO2modified manganese-based catalysts, then, the above-preparation catalysts are tested in the gas-solid catalytic micro-reactor. At the same time, BET, XRD and SEM are all tested to get more messages about physicochemical property of the catalysts, on the basic of which we probe into the chemical reaction mechanism on the surface of catalysts.Before the experiment, we select four factors to carry on orthogonal experiment, that is airspeed, oxygen concentration, temperature and the loading of the active components. The results show that the premium velocity is12000h-1, and the best of oxygen concentration is5%, in addition to this, temperature and the loading of the active components are discussed more particular in the activety test. According to the above experiment, we set the experiment parameter as the following:the the total flow rate,250mL·min-1,NO0.1%; NH30.11%;O25%, and the rest is N2, as balance air. In the experiment,0.5000g catalysts are loaded in the reactor, with the mass flow control to regulating the gas flow, then, the mixture gas pass into the reactor and come into contact with the catalysts, in which condition the SCR take place. Wth a gas analyzer tested, the catalyst activity test analyses temperature, SO2,life and the preparation of the catalyst, which includes the calcinations temperature and the active component loading, etc. Finally, we get the results:CeO2modified manganese-based catalysts have perfect low temperature DeNOx performance, meantime, the catalysts possess SO2anti-toxic and long service life. The active site on the catalyst’surface, which play an important role for the SCR reaction, is changed by composite oxide produced by CeO2and MnOx, so manganese-based catalysts modified by CeO2are successful.In the physicochemical property test, we get a much more deep understanding of the catalyst by means of BET, XRD and SEM experiments. On the base of all messages, the reaction mechanism on the catalyst’s surface is analysised. New active site produced by manganesd-based modified by CeO2on the surface of CeO2-MnOx/Al2O3contribute to the NO and NH3absorption. Thereby, SCR efficiency are enhanced, also, the catalysts service life is prolonged.Through this research, we develop manganese-based catalyses modified by CeO2. The catalyst shows high DeNOx performance at low temperature, anti-SO2poisoning and long life, which provide theoretical guidance for low temperature SCR catalysts large-scale application. In addition, more work should be done for the catalyst, such as the compact of water, combined with advanced technology about much more detail study to optimize the preparation of the catalyst. |
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