Promoting effect of microwave irradiation on CeO₂-TiO₂ catalyst for selective catalytic reduction of NO by NH₃

Jie Cheng¹，Liyun Song¹，Rui Wu¹，Shining Li¹，Yanming Sun¹，Hongtai Zhu¹，Wenge Qiu¹，Hong He^1,2

1. Key Laboratory of Beijing on Regional Air Pollution Control,And Beijing Key Laboratory for Green Catalysis and Separation,Beijing University of Technology2. Collaborative Innovation Centre of Electric Vehicles in Beijing

摘 要：In this work we prepared several CeO₂-TiO₂ catalysts for the NH₃-SCR reactionusing co-precipitation with assistance of microwave irradiation.The catalytic NH₃-SCR activities over CeO₂-TiO₂ catalysts at low temperatures are largely enhanced by the treatment of microwave irradiation,the operation temperature window is also broadened.For better understanding the promotion mechanism,the catalyst prepared by conventional co-precipitation with and without microwave irradiation treatment was characterized with H₂-TPR,NH₃-TPD,XPS,XRD and BET.Microwave irradiation treatment accelerates the crystallite rate of CeO₂-TiO₂ catalysts,and greatly enlarges their surface area by adjusting their microstructures.The resistance to SO₂ and H₂O is also improved via regulating the hierarchical pore structure by the microwave irradiation.Microwave irradiation treatment can also improve the redox property and increase the acid sites over the catalyst surfaces.The result of in situ DRIFTS suggests that the microwave irradiation treatment generates more Br?nsted acid sites on CeO₂-TiO₂-2 h catalyst,helpful in SCR reactions.XPS results show that after microwave irradiation on the CeO₂-TiO₂ catalysts,the surface demonstrates an elevated concentration of chemisorbed oxygen,consequently leading to better oxidation of NO to NO₂.Additionally,the molar ratio of Ce³⁺/Ce⁴⁺has been elevated after being treated by microwave irradiation,a vital factor in enhancing the NH₃-SCR activities.

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