Study On Heterogeneous Fenton Reaction Oxidation For NO Removal From Flue Gas Based On Iron-Based Catalyst Screening

Nitrogen oxide（NOx）poses serious hazards to human health and the ecological environment,and the requirements for controlling NOx emissions from boiler flue gas are becoming increasingly strict.Traditional denitrification methods such as selective catalytic reduction（SCR）have certain shortcomings in the actual operation of medium and low temperature flue gas（<200℃）.The oxidation absorption method is currently a relatively effective medium and low temperature flue gas denitrification technology,but the oxidation methods currently used,such as ozone,Cl O₂,KMn O₄,have problems such as high cost and secondary pollution.As an advanced oxidation process,heterogeneous Fenton process has the advantages of economy,efficiency,simple operation,stability and recyclability,and is a potential excellent medium and low temperature flue gas denitrification technology.In this paper,based on the theoretical calculation of quantum chemistry,the iron based heterogeneous Fenton catalyst is theoretically screened;A detailed experimental study is conducted on the removal of nitrogen oxide using heterogeneous Fenton technology on the theoretically screened catalyst,which is mutually verified with the theoretical results;Finally,the chemical reaction coupled with computational fluid dynamics（CFD）method is used to simulate the oxidation of NO by OH radical shower flue gas,which provides a reference for practical engineering research.The specific research work is as follows:（1）Theoretical research on screening heterogeneous Fenton catalyst:Firstly,a reasonable iron based catalyst model is established,and the reaction mechanism of heterogeneous Fenton reaction to generate OH radical is studied by using quantum chemistry calculation method.The reaction energy barriers of various catalysts are compared,and the iron based catalyst with better performance is selected.The theoretical results indicate that the iron based catalyst significantly reduces the reaction energy barrier for the decomposition of H₂O₂ to generate OH radical.The reaction energy barrier after adding the catalyst ranges from 61 to 115 k J/mol,with Pr GO-Fe exhibiting better catalytic performance（Ea=61.9 k J/mol）.This is because partially reduced graphite oxide（Pr GO）itself has a certain catalytic effect on the decomposition of H₂O₂,and it is also an electron rich material,which can provide additional electrons for the reduction of Fe³⁺,accelerate the reduction rate of Fe³⁺,and thus reduce the reaction energy barrier.（2）Experimental study on the removal of nitrogen oxide using heterogeneous Fenton technology:Guided by the theoretical results,a detailed experimental study is conducted on the removal of nitrogen oxide using heterogeneous Fenton technology.Iron based catalysts are prepared by impregnation method.Through sample characterization,it is found that the 16%Pr GO-15%Fe-Al₂O₃ catalyst has a smooth molecular surface,a more uniform pore structure,and a higher crystallinity of active substances,indicating good catalytic potential.Subsequently,in the experiment of removing nitrogen oxide,it is found that the catalytic performance of the catalyst is gradually enhanced with the increase of the reduction degree of graphite oxide added（the removal efficiency of nitrogen oxide increased from 82.5%to 93.5%when the vaporization temperature is 150℃）.Among all the tested catalysts,the 16%Pr GO-15%Fe-Al₂O₃ catalyst exhibited the strongest catalytic performance,which is consistent with the theoretical calculation results.Under optimal operating conditions,the removal efficiency of nitrogen oxide using this catalyst can reach96%.In addition,the rapid cooling of hydrogen peroxide after flashing not only avoids its own decomposition,but also promotes its surface contact reaction with the catalyst,which is the key to improving the efficiency of nitrogen oxide removal.（3）Numerical simulation study on NO oxidation in OH radical shower flue gas:In order to provide further reference for practical engineering research,Fluent software is used to numerically simulate the oxidation of NO by OH radical shower flue gas generated in the heterogeneous Fenton reaction.The result analysis found that temperature and OH/NO molar ratio are key factors affecting the oxidation of NO by OH radical;The incident velocity of the jet also has a significant impact on the efficiency of OH radical oxidation of NO.The optimal operating conditions are:temperature 473 K to 523 K,molar ratio of OH/NO maintained at around 1.4,jet velocity 10 m·s^-1,and flue gas velocity 3 m·s^-1.