The Study On Selective Catalytic Reduction Of Nitrogen Oxides By Methane

NO_X is one of the major pollutants in the atmosphere, and the abatement of NO_X has been a hotspot of study all over the world. Selective catalytic reduction (SCR) of NO by methane has a wide application background. However, only a few zeolite-based In-, Pt- and Pd- catalysts have been found to be active for this reaction, which are sensitive to the reaction conditions, meanwhile noble metals are now facing the crisis of resource scarcity. Therefore, in recent years, studies with transition metals have attracted much attention.USY possesses the advantages of resisting water and SO₂, which was widely used to petrolic catalytic cracking. Very limited work has been done on USY as supports of DeNO_x catalysts. So it is of great theoretical and practical significant to investigate the properties of USY-based catalysts in DeNO_x reaction. In this dissertation, transition metals, which were specially supported on USY by wet-impregnation method, which were employed to improve the DeNO_x activity.In CH₄-SCR reaction system, 5wt.%Mn/H-USY and 15wt.%Ni/H-USY catalysts were found to be activer in the CH4-SCR. The addition of noble metals components to enhance the activities of USY-based catalysts for the SCR of NO with CH₄ was studied, and they show higher activities than the other zeolite-based catalysts, which were 52% and 48% on Mn/H-USY, Ni/H-USY respectively. Otherwise the addition of Zn component to Mn/H-USY catalyst enhance water-resistant ability than the other zeolite-based catalysts, which have been reported to have high activities.The DRIFT technique was first used to comprehensively study the characteristics of pyride and NO adsorption on catalysts. The results strongly suggested that the acidity impacted the activity and NO was oxided to NO₂ with surface oxygen, and NO₂ exerted important effect on the CH4-SCR process. Simultaneity, the mechanisms of Mn/H-USY, Ni/H-USY and the additions of other components catalysts in CH₄-NO-O₂ reaction were examined by means of BET, XRD, H₂-TPR, DRIFT technologies. It was found that it had strong interactions among different compositions and carries of the catalysts on the catalytic activity. It show that although the Pd species was added on Mn/H-USY catalyst, the incorporation of Pd does only alter the behavior of the Mn dispersed on the H-USY support, and the active sites and supports had still strong...