Influence of zirconium modified carriers on the NH3-SCR performance of manganese-cerium composite catalysts
A hydrothermal method was employed to synthesize cerium-zirconium(CenZr1-n)supports with different ratios,and a series of composite catalysts were then prepared by impregnating MnOx as the active component.The catalytic performance of these catalysts in the selective catalytic reduction of NOx with ammonia(NH3-SCR)was investigated.The catalysts were characterized by various techniques such as XRD,Raman,SEM,N2 adsorption-desorption,H2-TPR,NH3-TPD,and XPS,to examine their structure,morphology,surface acidity,and surface oxidation state.The results indicated that CenZr1-n prepared by the hydrothermal method exhibited better NH3-SCR catalytic activity than CeO2 supports.Similarly,8Mn/CenZr1-n catalysts show improved performance.Among them,the 8Mn/Ce0.8Zr02 catalyst exhibited the best catalytic activity,with T50 and T90 of 100.2℃ and 130.2℃,respectively.The working temperature window was 245.5℃(130.2-377.2℃),and 100％NO conversion rate was maintained between 159.6℃ and 349.0℃.The catalyst demonstrated better low-temperature reduction performance and more acidic sites,which facilitated the adsorption and reduction of reactants at low temperatures.Furthermore,it had a relative high content of high-valence Mn4+species on the surface,which contributed to enhancing NH3-SCR catalytic activity.
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