School of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, University of Jinan, Jinan 250022, China.
Environ Sci Technol. 2012 Sep 4;46(17):9600-5. doi: 10.1021/es301661r. Epub 2012 Aug 21.
The amorphous Ce-Ti mixed oxides were reported to be catalysts for selective catalytic reduction of NO(x) with NH(3), 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-Ti amorphous oxide shows higher activity than its crystalline counterpart at lower temperatures. Moreover, the presence of small CeO(2) crystallites as for the impregnated sample is deleterious to activity. The Ce-O-Ti 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 H(2) (H(2)-TPR), in situ FTIR spectra of NO adsorption, X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine-structure (XAFS). Lastly, the Ce-O-Ti structure was directly observed by field-emission TEM (FETEM).
无定形的 Ce-Ti 混合氧化物被报道为用于选择性催化还原 NO(x)与 NH(3)的催化剂，尽管 Ce 的含量较低，但 Ce 而不是 Ti 作为其溶剂。使用带有选区电子衍射 (SAED) 的 X 射线粉末衍射 (XRD) 和透射电子显微镜 (TEM) 对无定形催化剂进行了表征。无定形的 Ce-Ti 氧化物在较低温度下表现出比其晶态对应物更高的活性。此外，浸渍样品中存在的 CeO(2)微晶对活性是有害的。使用氢气程序升温还原 (H(2)-TPR)、NO 吸附的原位傅里叶变换红外光谱 (in situ FTIR)、X 射线光电子能谱 (XPS) 和 X 射线吸收精细结构 (XAFS)，首次证实了具有原子尺度 Ce 和 Ti 相互作用的 Ce-O-Ti 短程有序物种是活性位。最后，通过场发射透射电子显微镜 (FETEM) 直接观察到了 Ce-O-Ti 结构。
