Preparation Of Nickel Foam Supported MnO₂@CeO₂ Core-Shell Catalyst And Its SCO Denitration Performance

The nitrogen oxide-containing flue gas emitted by coal combustion can cause acid rain,photochemical smog,and even destroy the ozone layer.It also causes serious harm to human life and health and safety.Therefore,it is urgent to control and reduce nitrogen oxide emissions.The NOx selective catalytic oxidation method(SCO)has the advantages of high catalytic activity and low application temperature.In the catalytic oxidation reaction,the catalyst is the core of the reaction,so the development and selection of the catalyst in the application of SCO is very important.At present,Mn-based catalysts are widely used due to their high catalytic activity,but their sulfur resistance is poor.In order to develop a Mn-Ce composite catalyst with high catalytic activity and excellent sulfur resistance,CeO2 with a spherical structure was prepared by hydrothermal method,and the influence of different preparation conditions on the formation of CeO2 was studied by designing orthogonal experiments.good preparation conditions.Then CeO2 was used as the carrier,and a certain concentration of manganese precursor was added to develop a MnO2@CeO2 core-shell catalyst with MnO2 as the core and CeO2 as the shell.Combined with SCO activity evaluation,SEM,TEM and XRD characterization methods,the effects of different manganese-cerium ratios and core-shell morphology on the denitrification performance of the catalyst were studied.Finally,in order to improve the disadvantages of the catalyst itself with small specific surface area and unstable active centre,the foamed metal nickel support was modified by the equal volume impregnation method,and then the developed core-shell catalyst was supported on it to prepare the foamed metal nickel support.MnO2@CeO2 core-shell catalyst,and the mechanism of its catalytic activity and sulfur resistance was analyzed.The experimental results show that:(1)When the concentration of cerium chloride solution is 0.6 mol/L,urea is 30 g,glucose is 40 g,and the hydrothermal temperature is 200℃,the prepared CeO2 catalyst has uniform particle size and high dispersibility.Its catalytic activity is better than that of catalysts prepared under other conditions,and the conversion rate of NO at 250℃ is up to 85%;(2)The denitration performance of the MnO2@CeO2 composite catalyst is significantly better than that of the CeO2 catalyst alone.At the same time,the MnO2@CeO2 core-shell catalyst prepared with MnCl2·4H2O as the manganese precursor The NO conversion rate is better than that of the other two manganese precursor catalysts;(3)When the loading is 10%and the loading time is 6 h,the denitration rate of the foamed metal nickel supported MnO2@CeO2 core-shell catalyst exceeds 97%,and the activity is stable;(4)When SO2 gas is introduced into the SCO reactor,the denitration rate of the three catalysts all decrease significantly,but when the introduction of SO2 gas is stopped,the nickel foam The denitration performance of the supported MnO2@CeO2 core-shell catalyst has been restored,which indicates that the catalyst has excellent sulfur resistance.