Experimental Study On The Removal Of Nitrogen Oxides From Flue Gas By Iron-Based Metal-Organic Framework Materials

Nitrogen oxides（NOx）are one of the air pollutants that are of great concern today,and their excessive emissions can cause environmental problems such as acid deposition,photochemical smog,and increased ozone concentration near the ground,which have a serious impact on the ecological environment.Selective catalytic reduction（SCR）is the most effective NOx technology to control emission.It has the advantages of high denitrification efficiency and wide application range,so it is widely used in the coal power industry.However,it has disadvantages such as low catalytic activity under low temperature conditions,and it is difficult to meet the high-efficiency denitration requirements of steel,building materials and other industrial boilers.The development of medium and low temperature denitrification technology is urgently needed.The key issue is the development of high-efficiency medium and low temperature catalysts.MOFs materials exhibit strong catalytic activity in low-temperature denitration reactions due to their high porosity,strong coordination connection between metal and organic ligands,and containing unsaturated metal active sites.At present,MOFs materials are highly efficient The research of SCR catalyst has attracted wide attention of scholars.The main work of this research is as follows:1.MIL-101（Fe）was successfully synthesized by microwave hydrothermal method,and the denitration efficiency of MIL-101（Fe）was investigated experimentally.The results showed that the denitration efficiency can reach more than 70%in the temperature range of 375～450℃.In order to further improve its catalytic activity,the composite MOFs Cu _X/MIL-101（Fe）were prepared by doping with different molar ratios of Cu.The modification of MIL-101（Fe）was realized,and the doping ratio and the amount of catalyst added were investigated.The impact on the denitrification effect.The results showed that the Fe/Cu molar ratio was 1/2,and the Cu₂/MIL-101（Fe）catalyst with an addition amount of 0.15g had the highest catalytic activity,and the denitrification efficiency was increased to 93%.At the same time,the water and sulfur resistance of the catalyst was investigated,and it was found that SO₂had an irreversible effect on it,while the effect was slight when H₂O and SO₂ were added at the same time.Through a series of characterization,the physical and chemical properties of the catalyst before and after the reaction were analyzed,and it was confirmed that there were two active metals on the surface of the catalyst,and there was no obvious change in the crystal structure,surface elements,etc.before and after the reaction.2.Using Cu _X/MIL-101（Fe）series materials as the precursor,the carbon-based metal oxide Fe _XCu _YO-C was obtained by thermal decomposition at 480℃and N₂,and the effect of metal ratio and catalyst addition on the denitration performance was investigated.The study found that the optimal addition amount of the sample with a Fe/Cu molar ratio of 1/2 is 0.1g,and the highest denitration efficiency can reach 94%.Comparing to Cu₂/MIL-101（Fe）,it is found that the pore volume of Fe₁Cu₂O-C increases,which is the main reason for improving the denitrification effect.The resistance experiment shows that the resistance trend of Fe1Cu2O-C and Cu2/MIL-101（Fe）is basically similar.Characterization and analysis showed that there was no significant change on the surface of the catalyst after the reaction,indicating that it can be used repeatedly for a long time.The catalyst can be used as a potential high-temperature SCR catalyst replacement material.