| Industrial kiln flue gas has the characteristics of high concentration of fly ash, SO2 and NOx, and low gas temperature(200～300℃). However, the operating temperature of traditional SCR(Selective Catalytic Reduction) denitrification catalyst is usually high (about 350～450℃), and the temperature window is narrow, which makes it is not appropriate for denitrification condition of industrial kiln flue gas. Selective catalytic reduction is widely used for removal of nitrogen oxides emitted from stationary source. In accordance with lack of industrial kiln flue gas denitrification technology, the development of SCR denitrification technology at middle-low temperature will have a wide application prospect, and the development of catalyst is the key.In this dissertation, combinatorial chemistry was adopted, and the activities of supported composite transition metal oxides catalysts prepared by impregnation method for middle-low temperature SCR of NOx were evaluated. VCu/TiO2 catalysts with potential SCR activity at middle-low temperature were obtained after screening and were targeted for further investigation.Experimental result showed that 2V16Cu/TiO2(500) (2V and 16Cu denote V2O5 and CuO account for 2% and 16% of the total catalyst mass respectively, while 500 represents the calcinations temperature 500℃) prepared by impregnation method exhibited the best activity and quite wide temperature window in a series of VCu/TiO2 catalysts. At 225℃,97.3% NOx conversion was obtained with a gas hourly space elocity of 6.0×104h-1. And it reached 100% at 250～300℃. Sulfur-resistance study results of the Catalysts showed that the sulfur-resistance of 2V16Cu/TiO2(500) prepared by the introduction of vanadium pentoxide was a little better than that of 16Cu/TiO2(500) at 250℃and 6.0×104h-1 after feeding SO2 (volume fraction is 0.06%). The surface and bulk properties of this catalyst system were examined using X-ray Diffraction (XRD), Tempertature-Programed Reduction (TPR), Raman, X-ray Photoelectron Spectroscopy (XPS) and other characterization techniques. It was found that CuO was the key active component of the VCu/TiO2 catalysts, and which improved the catalytic activity at middle-low temperature significantly. The increase of Copper content contributed to CuO crystals formation and NOx conversion improvement. Appropriate V5+, V4+ and Cu2+ enriched on surface benefited the middle-low temperature SCR denitrification activity.Despite the series of VCu/TiO2 catalysts exhibited the high activity, their sulfur-resistance was not good. Therefore, VCu/TiO2 catalysts were modified. Combinatorial chemistry was adopted, and the activities of supported ternary metals composite oxides catalysts prepared by impregnation method for middle-low temperature SCR of NOx were evaluated. Two series of VCuMn/TiO2 and VCoMn/TiO2 catalysts were obtained after screening and were targeted for follow-up study.A preliminary study on a series of VCuMn/TiO2 catalysts were carried out and the results showed that 2V2Cu8Mn/TiO2(500) and 2V8Cu2Mn/TiO2(500) exhibited better activity. At 200℃, above 70% NOx conversion were both obtained with a gas hourly space elocity of 6.0×104h-1. NOx conversion of 2V2Cu8Mn/TiO2 and 2V8Cu2Mn/TiO2 reached 100% at 275～325℃and 300℃, respectively. In addition, sulfur-resistance of the series of VCuMn/TiO2 catalysts were improved.2V2Cu8Mn/TiO2 performed the best sulfur-resistance. NOx conversion was above 60% at 250℃and 6.0×104h-1 after feeding SO2 (volume fraction is 0.06%), when SO2 was stopped, the catalytic activity rebounded little.A series of VCoMn/TiO2 catalysts were also investigated and it showed that 2V5Co5Mn/TiO2(500) exhibited the best middle-low temperature SCR denitrification performance. At 225℃, NOx conversion reached 87.1% and then above 90.0% NOx conversion was maintained. And the temperature window is wide. Preliminary study of catalysts' sulfur-resistance showed that 2V2Co8Mn/TiO2,2V4Co6Mn/TiO2 and 2V5Co5Mn/TiO2 all had better sulfur-resistance. NOx conversion were all above 75% after 1 h, and it reached above 90% after 4 h.
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