Characteristics Of NO Reaction On The Three Metal Precious Metal Catalysts Under The Condition Of Enrich Oxygen

Nitric Oxide, mainly NO and NO2,is major pollutant in the atmosphere. NOis not only toxicate, but also can be the cause of photochemical smog and acidrain, both of which have great impact on human’s life. Among the variousemission sources of NO, the motor vehicle exhaust is a notable one. Moreover, asthe global resources having exhausted, more and more motor veichles t end toadopt the lean-burn technology, giving rise to the efficacy lose of TWCs andleading to the abnormal decomposition of NO. Therefore, it has been a hotproject of atmosphere control measure to reveal the reaction process of NO onthe catalyst surface under the condition of oxygen-enrich, and to develop thecatalyst that can efficiently decompose NO for ox ygen-enrich condition.This thesis is based on a previous work of our research team. The mainsubject of this work is to study the process of NO reaction on the surface of Pd,Au and Ag catalysts and how the variation of preparation condition of catalystimpact on this process. And the study of the effect of adding SO2, H2O steam, COand C2H4in oxygen-enrich atmosphere for NO reaction is also an important partof this work.Temerature programmed reaction system and FTIR was used to research thereaction of NO on noble metals. The results showed: The processes of NOdecomposition in oxygen-enrich atmosphere with each of these three noble metalcatalysts are almost the same. As the reaction temperature elevates, the processas following: NO was oxided to NO2first; NO and NO2molecules are absordedon the surface of catalyst;2N(ad) or N(ad)+NO(ad) become N2/N2O. There willbe a O(*) on the active site of the catalysts after NO decomposition, O(*) canoxide NO to NO2.The reactions are mainly reductions and oxidations.The preparations methods on the catalysis of NO in following ways: for Pd,in1.5%H2/N2atmosphere with a temperature of500℃, the catalyst Pd/TiO2with a density of5%promotes both of reactions of NO. For Au, in reductionatmosphere with a temperature of400℃, the catalyst Au/ZrO2with a density of1%promotes the reduction reaction of NO; in H2/N2atmosphere with atemperature of600℃, the catalyst Au/ZrO2with a density of5%promotes theoxidation reaction of NO. For Ag, in N2atmosphere with a temperature of600℃, the catalyst Ag/TiO2with a density of5%promotes reactions of redox.. After different types of gas are added into the reaction atmosphere, properdensity of SO2promote the redox reaction of NO catalyzed by Pd and Ag,whereas all other densities inhabit the reaction. The water added into thereactions reactions, promote the reduction of NO for Au and Ag; but for Pd thereaction was inhabited. For all the precious metals, any concentration of waterwill inhibit the reactions of NO oxidation. CO and C2H4promoted the readucionof NO and inhibit the oxidation reaction of NO.