Ce鈥揟i Amorphous Oxides for Selective Catalytic Reduction of NO with NH3: Confirmation of Ce鈥揙鈥揟i Active Sites

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• 作者：Ping Li ; Ying Xin ; Qian Li ; Zhongpeng Wang ; Zhaoliang Zhang ; Lirong Zheng
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：September 4, 2012
• 年：2012
• 卷：46
• 期：17
• 页码：9600-9605
• 全文大小：415K
• 年卷期：v.46,no.17(September 4, 2012)
• ISSN：1520-5851

文摘

The amorphous Ce鈥揟i mixed oxides were reported to be catalysts for selective catalytic reduction of NO_x with NH₃, in which Ce and not Ti acts as their solvent in spite of the fact that Ce is low in content. The amorphous catalysts were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) equipped with selective area electron diffraction (SAED). The Ce鈥揟i amorphous oxide shows higher activity than its crystalline counterpart at lower temperatures. Moreover, the presence of small CeO₂ crystallites as for the impregnated sample is deleterious to activity. The Ce鈥揙鈥揟i short-range order species with the interaction between Ce and Ti in atomic scale was confirmed for the first time to be the active site using temperature programmed reduction with H₂ (H₂鈥揟PR), in situ FTIR spectra of NO adsorption, X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine-structure (XAFS). Lastly, the Ce鈥揙鈥揟i structure was directly observed by field-emission TEM (FETEM).