| Nitrogen oxide(NOx),one of serious air pollutants to acid rain,photochemical smog and ozone,which are quite harmful to life and cause serious environmental disruption. Therefore,there is a worldwide effort to discover improved solutions for the effective removal of NOx in the exhaust gases. The automobile afterward treatment is one of the effective ways. Until now,however,no suitable catalyst that can effectively reduce NO has been found although the chemical reaction is thermodynamically favorable at low temperatures in lean burn engines. Previous studies have shown that the highly active catalysts,for example,noble metals and metal oxides,usually exhibit a strong affinity for atomic oxygen,and can hold the adsorbed atomic oxygen at higher temperatures. The tightly bound oxygen species on the surface occupies the active sites for NO adsorption and decomposition of NO on the catalyst surface,resulting in catalyst deactivation. The mechanism and application of NOx reduction of engine exhaust over modified carbon fiber was chosen as the subject of study. The following is the content of this work.1. The significance on the control technology of the NO,was firstly discussed. The development and present state of the control technology of automobile and diesel exhaust emission was also summarized.2. various kinds of activated carbon fibers(ACF) were studied in the reduction of NO as reducing agent. By use of thermogravimetry(TG) > temperature programmed desorption(TPD) and scanning electron microscope(SEM) analysis technique,ACF was evaluated and selected successfully,and the best ACF was polyacrylonitrile based activated carbon fiber.3. Two kinds of based activated carbon fiber (ACF) polyacrylonitrile were selected in order to study their NO reduction properties. Experimental results showed that the NO reduction activity of HNOj dipped ACF is higher than that of non-treated one,and that of 2~4 hours HN03 dipped ACFs is best. In order to know the adsorption properties of various oxygen containing gases on ACFs,TPD experiments carried over ACF showed that the adsorption abilities of CO,NO and 02 on HN03 dipped ACFs are higher than that on non-dipped ACFs,but C02 has reverse result. We put forward according to literature and experiment results,a first order kinetic equation was used to treat experimental data,and Arrhenius equations for four different ACFs carrying NO reduction were obtained. Results show that NO reduction activity of HN03 dipped ACF always higher than that of non-dipped one.4. The activated carbon fiber (ACF) was used as supporter for the preparation of the copper-based catalyst,that was prepared by conventional impregnation method. The experimental results indicate that the copper modified ACF shows excellent performance for the removal of NO. for example,The NO reduction activity of the copper modified ACF is higher than HN03 dipped ACF and non-treat ACF,and that is higher than other metal ion modified ACFs. By use of thermogravimetric analysis(TGA) technique,the copper modified ACF,HNOS dipped ACF and non-treat ACF is evaluated and selected successfully. Otherwise,Mathematical methods are used to treat the TG experimental curves. Major kinetic parameters in relation to each oxidation reaction are calculated. This provides another simple analytical way to evaluate the ACF that developed.5. By means of TPR,TPD and TG,the exist of oxygen containing groups on various kinds of ACF(including HNOj modified and Cu modified ACF) were proved. Reaction of NO and various ACF was carried in micro reactor system and the products of this reaction were analyzed. The existence of oxygen containing groups on ACF effects NO removal reaction seriously. The effect of CO on this reaction was studied too.6. construction shape,flow resistance of automobile catalytic converter have significant effect on the performance of catalysts and engines. Consequently,effect of various construction shape factors and flow resistance of catalytic converter upon its property is researched and optimum design...
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