Synergetic catalytic removal of chlorobenzene and NO_χ from waste incineration exhaust over MnNb_0.4Ce_0.2O_χ catalysts:Performance and mechanism study

Bo Yang¹，Qijie Jin^2,3，Qiong Huang¹，Mindong Chen¹，Leilei Xu¹，Yuesong Shen²，Haitao Xu²，Shemin Zhu²，Xiujun Li³

1. Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET),Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,School of Environmental Science and Engineering,Nanjing University of Information Science & Technology2. Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites,College of Materials Science and Engineering,Nanjing Tech University3. Department of Chemistry and Biochemistry,Environmental Science & Engineering,and Biomedical Engineering,University of Texas at EL Paso

摘 要：Nb doped MnCe_0.2O_x complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NO_x and chlorobenzene（CB） at low temperatures.The MnNb_0.4Ce_0.2O_x catalyst with a molar ratio of Nb/Mn=0.4 exhibits excellent activity and the NOx and CB removal efficiency reaches 94.5% and 96% at 220℃,respectively.Furthermore,the NO_x and CB removal efficiency of MnNb_0.4Ce_0.2O_x still remains above 80% after injecting 300 ppm SO2 and 7 vol% H₂ O for 36 h.In addition,the presence of CB and NO_x+NH₃ can improve the NOx and CB removal efficiency of MnNb_0.4Ce_0.2O_x, respectively.The analysis results from N2-BET,Py-IR,H₂-TPR and NH₃-TPD reveal that the introduction of Nb increases the average pore size,pore volume and surface area,promoted the growth of Lewis acid amount obviously,and enhances redox ability of MnCe_0.2O_x at 100-250 ℃.Moreover,the molecular migration process of NO_x,NH₃,CB and SO₂ in NH₃-SCR and CB oxidation reaction over MnNb_0.4Ce_0.2O_x catalysts were systematically studied.In situ DRIFTS,FT-IR and XPS also confirm that the adsorption of sulfate species and SO₂ on the surface of MnNb_0.4Ce_0.2O_x is inhibited effectively by the introduction of Nb in the presence of SO₂ and H₂ O.Moreover,Nb additives also enhance the structural stability of MnNb_0.4Ce_0.2O_x,due to the interactions among Mn,Nb and Ce.The NH₃-TPD,H₂-TPR and in situ DRIFTS results also confirm that the MnNb_0.4Ce_0.2O_x still retains abundant acid sites and high redox ability in the presence of SO₂ and H₂O.In summary,MnNb_0.4Ce_0.2O_x catalysts represent a promising and effective candidate for controlling NO_x and CB at low temperatures.

关键词：