Li Huang,Yiqing Zeng,Yibo Gao,Hu Wang,Yuhao Zong,Zhengfeng Chang,Shule Zhang,Pei Han,Yang Yu
The oxidation of SO 2 into SO 3 promote the formation of NH 4 HSO 4 (ABS), which can cover surface active sites catalyst, and then leading to the decrease of NH 3 -SCR De-NO x activity. In this work, phosphorus species were loaded on the V 2 O 5 -MoO 3 /TiO 2 De-NO x catalyst to enhance its SO 2 resistance via inhibiting the SO 2 /SO 3 conversion. XRD and N 2 -adsorption results showed that phosphorus has little impact on the structure and pore property of the catalyst. The results of XPS , H 2 -TPR, and NH 3 -TPD analyses illustrated that suitable amount of phosphorus (1%) increases the content of polymeric vanadate and chemisorbed oxygen (O α ) of the catalyst, which is benefit to the SCR process. Phosphorus species decreases the SO 2 absorbability and SO 2 oxidation activity of V-Mo-P/Ti catalysts, thus it exhibits higher NH 3 -SCR activity than that of the P-free catalyst at presence of SO 2 due to the lower SO 2 /SO 3 conversion and fewer amount of NH 4 HSO 4 deposition.
Lead (Pb) species are inescapable constituents of the flue gas from coal-fired power plants and other thermal devices, which can cause impeding effects on the selective catalytic reduction (SCR) reactions. Here, the poisoning effects of Pb on the V 2 O 5 -MoO 3 /TiO 2 type SCR catalyst were examined. The poisoned catalysts were prepared by the solid diffusion and incipient wetness impregnation (IWI) methods. The catalytic activity tests indicated that the Pb-doped catalyst prepared by the IWI method suffered a considerable drop in catalytic activity, while a slender influence was observed on the Pb-loaded catalysts prepared by solid diffusion method. Comprehensive characterizations and density functional theory (DFT) calculations were performed on the fresh and poisoned catalysts prepared by the IWI method to unveil the deactivation mechanism. The results showed that Pb species covered the active sites (V species) on the catalyst surface, resulted in the decrease in chemisorbed oxygen, hence reducing the surface acidities. The decrease in reducibility of the catalyst was an important factor for poisoning of the catalyst. Moreover, Pb species reacted with MoO 3 to form PbMoO 4 which agglomerated on the catalyst surface to further deactivate the catalyst.
The development of novel low-temperature selective catalytic reduction (SCR) denitrification catalysts is a crucial research direction for reducing pollution and carbon emissions. Although V2O5-MoO3/TiO2 catalysts have been widely used in commercial applications, achieving effective SCR denitrification for low-temperature flue gases remains a significant challenge. In this study, the catalytic efficiency of the catalysts was systematically investigated and optimized by constructing Pearson linear correlation coefficient models between catalytic activity and different pore structures, substrate crystal planes, and active site components and properties, etc. Through comprehensive characterizations and experiments, anatase TiO2 loaded with 3% V2O5 and 10% MoO3 was developed and demonstrated excellent catalytic activity and stability even in high sulfur content and low-temperature environments. The catalyst was deployed in a pilot plant for over two years, consistently achieving a monthly average denitrification efficiency of over 67% and maintaining an outlet NOx concentration below 50 mg/Nm³. This study provides a robust and efficient low-temperature catalyst for SCR denitrification and offers valuable insights for future catalyst optimization.
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