Research On The Design Of Manganese Oxide Catalysts For The Removal Of Nitric Oxide And Chlorobenzene

Under the upcoming stringent flue gas pollutants control standards,the control of flue gas from steel sintering and municipal solid waste incineration as representatives has re-ceived much attention.The flue gas has two similar characteristics:the temperature of flue gas is usually lower than 300^?C;the flue gas contains polychlorinated dibenzo-p-dioxins and dibenzofurans?PCDD/Fs?,chlorobenzene,other chlorinated organic compounds,and nitric oxide.This work utilizes catalysis method and designs bi-functional catalysts to simultaneously reduce nitric oxide and oxidize chlorobenzene.?-MnO₂is selected as the object catalyst to investigate its microscope structure and catalytic performance,then a microscope mechanism for the enhancement of redox property by doping method is established,and the core-shell structure catalysts to promote the resistance to SO₂are further designed.The major results and highlights are listed as below:?1?By high resolution transmission electron spectroscopy and theoretical simulation results,the surface open tunnel structure of?-MnO₂is established.The removal of surface K⁺exposes more active reaction sites for catalysis reaction.These abundant redox sites promote low temperature selective catalytic reduction?SCR?reaction and the oxidation of chlorobenzene.The surface open tunnels are the microscope base for the good catalytic performance of?-MnO₂.?2?Fe-doping,as a representative solid solution method,further increases the redox property of?-MnO₂.This is because of the increase of abundant oxygen vacancies induced by Fe-doping.To balance the charge inequivalence,the valence of Mn⁴⁺decreases toward Mn³⁺while maintaining the crystal structure of?-MnO₂.This induces Jahn-Teller distortion in the catalysts,thus elongating some Mn-O bond length,which will be feasible to break.Therefore,the redox property of the catalysts will be enhanced.?3?The CeO₂shell with a depth of 10 nm is synthesized outside?-MnO₂,consisting of CeO₂nanoparticles with a diameter less than 5 nm.CeO₂shell can decrease the valence of Mn,thus increasing its redox property.Besides,CeO 2 can bind SO₂strongly and in priority to MnO₂,thus functioning as the sacrifice to protect?-MnO₂from SO₂poisoning.?4?The catalysts synthesized in this work all behave as promising catalysts to remove nitric oxide and chlorobenzene at 200^?C.When mixing these reactants,both catalytic reactions are slight suppressed.