Structure and catalytic property of CeO2-ZrO2-Fe2O3 mixed oxide catalysts for diesel soot combustion： Effect of preparation method

• Published in: Journal of rare earths Vol. 32; no. 9; pp. 817 - 823
• Main Author: 顾振华 桑秀丽 王华 李孔斋
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2014
• Subjects: Ce0.5Fe0.30Zr0.20O2 mixed oxides; hydrothermal method; interaction; rare earths; solid solution; soot combustion; 催化性能; 制备方法; 氧化物催化剂; 氧化铁; 氧化铈; 混合; 燃烧; 碳烟氧化; interaction; soot combustion; solid solution; Ce0.5Fe0.30Zr0.20O2 mixed oxides; hydrothermal method; rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/S1002-0721(14)60147-2

A series of Ceo.sFeo.30Zr0.20O2 catalysts were prepared by different methods （co-precipitations method, citric acid sol-gel method, impregnation method, physical mixed method, and hydrotherrnal method） and characterized by X-ray diffraction （XRD）, Raman spectroscopy, Brunauer-Emmett-Teller （BET） and H2-TPR measurements. Potential of the catalysts in the soot oxidation was evaluated in a temperature-programmed oxidation （TPO） apparatus. The results showed that all the Fe3＋ and Zr4＋ were incor- porated into ceria lattice to form a pure Ce-Fe-Zr-O solid solution for the co-precipitation sample, but two kinds of Fe phases ex- isted in the Ce-Fe-Zr-O catalysts prepared by other methods： Fe3＋ incorporated into CeO2 lattice and dispersed Fe2O3 clusters. The free Fe2O3 clusters could improve the activity of catalysts for soot oxidation comparing with the pure Ce-Fe-Zr-O solid solution owing to the synergetic effect between free Fe2O3 and surface oxygen vacancies. In addition, the activity of catalysts strongly relied on the surface reducibility of free Fe2O3 particles. Holding both abundant free Fe2O3 particles and high oxygen vacancy concentration, the hydrothermal Ce0.5Fe0.3Zr0.202 catalyst presented the lowest Ti （251℃, ignition temperature of soot oxidation） and Tm （310 ℃, maximum oxidation rate temperature） for soot combustion （with tight-contact between soot and catalysts） among the five samples. Even after aging at 800 ℃ for 10 h, the Ti and Tm were still relatively low, at 273 and 361 ℃, respectively, indicating high catalytic stability.