Preparation,Characterization Of The Catalyst For Decomposition Of The High Concentration NO And Its Activity Evaluation

With the rapid development of the marine transportation,the pollution of nitrogen oxides and sulfur oxides in the exhaust gas of marine diesel engine was becoming more and more serious to the atmosphere.In 2008,the International Maritime Organization?IMO?adopted the amendment to annex VI of the MARPOL convention,which made more stringent requirements for the emission standards of sulfur oxides in the exhaust gas of ships.Among the kinds of denitration technologies of the marine exhaust gas,the direct decomposition method of NO had been widely concerned because of its advantages,such as simple process,no consumption of the reducing agent,no secondary pollution and the product was of innocuous and harmless.The Cu-ZSM-5 catalyst with H-ZSM-5 molecular sieve as the carrier and no silicon and aluminum adhesive was prepared by the ion exchange method under the ultrasonic action in this paper,the effects of different preparation conditions and reaction conditions on the denitrification activity of the Cu-ZSM-5 catalyst were studied,the optimum preparation process and the best reaction conditions of the Cu-ZSM-5 catalyst were determined,and the Cu-ZSM-5 catalyst was characterized by X ray diffraction,X fluorescence spectroscopy,N₂ adsorption and desorption and the field emission scanning electron microscopy.The results show that,compared with the ion exchange method without the ultrasonic action and solid dispersion method,the Cu-ZSM-5 catalyst prepared by the ultrasonic ion exchange method had the more uniform particle distribution,the larger specific surface area and the higher denitrification activity.Under the condition of the reaction temperature was 773K,Si and Al ratio was 38,the concentration of Cu²⁺was 0.01mol·L^-1,the exchange temperature was 45°C,the ion exchange times were 3 times,the loading amount of Cu was 3.73%,the reaction space velocity was 2800h^-1 and no oxygen,the decomposition rate of NO of the Cu-ZSM-5 catalyst was 79.9%.In order to improve the denitrification activity at the low temperature and the oxygen resistance of the Cu-ZSM-5 catalyst,the Cu-ZSM-5 catalyst was modified by doping Ag and Ce ions in this paper,the Ag/Cu-ZSM-5 catalyst and the Ce/Cu-ZSM-5 catalyst with H-ZSM-5 molecular sieve as the carrier and no silicon and aluminum adhesive ware prepared by the improved ultrasonic ion exchange method,the effects of different reaction conditions on the denitrification activity were studied,and the Ag/Cu-ZSM-5 catalyst and the Ce/Cu-ZSM-5 catalyst were characterized by X ray diffraction,N₂ adsorption and desorption,Flourier transform infrared spectroscopy and the field emission scanning electron microscopy.The results show that,under the condition of the reaction temperature was 663K,Si and Al ratio was 38,the concentration of Ag⁺was 0.04mol·L^-1 and the concentration of O₂ was 5%,the decomposition rate of NO of the Ag/Cu-ZSM-5 catalyst was 78.1%;and under the condition of the reaction temperature was 623K,the Si and Al ratio was38 and the concentration of O₂ was 5%,the decomposition rate of NO of the Ce/Cu-ZSM-5 catalyst was 56.9%,indicating that the Ag/Cu-ZSM-5 catalyst and the Ce/Cu-ZSM-5 catalyst had the good oxygen resistance.And compared with the Cu-ZSM-5 catalyst,the optimum decomposition temperature of the Ag/Cu-ZSM-5catalyst and the Ce/Cu-ZSM-5 catalyst decreased by 110K and 150K respectively,indicating that they had the fine denitration activity at the low temperature.The innovation of this paper was that the Cu-ZSM-5 catalyst which was of ideal decomposition activity for the high concentration NO was prepared by ultrasonic chemical method,and the Cu-ZSM-5 catalyst was doped by Ag and Ce ions to improve its denitrification activity at the low temperature and antioxidant capacity.