Subject Area物理化学
Effect of α-Fe2O3 morphology on NO reduction by CO
Mou XL(牟效玲); Li Y(李勇); Huang XM(黄秀敏); Shen WJ(申文杰)
Conference Name6th International Conference on Environmental Catalysis
Conference Date2010-9-12
Conference Place中国
Funding Organization中国科学院生态环境研究中心
AbstractEffect of α-Fe2O3 morphology on NO reduction by CO Xiaoling Mu, Yong Li, Xiumin Huang, Wenjie Shen* State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China *Corresponding author: +86-411-84379085, shen98@dicp.ac.cn Introduction The catalytic reduction of NO by CO is an essential process in the three-way catalytic converter used in abating automobile exhaust, where Pd, Pt and Rh-based noble metals act as the major catalytic components. [1]. Because of the high cost and limited available sources of precious metals, considerable efforts have been made to utilize transition metals and their oxides. Among them, iron oxides seem to be the most promising candidate. Density functional theory analyses have revealed that Fe2O3 clusters are excellent catalysts for CO oxidation and NO reduction [2], but experimental studies on Fe2O3 for NO+CO reaction are reported scarcely. Here, we examined α-Fe2O3 materials with different morphologies (fibrous-like and small nanosheets) for NO reduction by CO, and the fibrous-like α-Fe2O3 shown exceptionally high activity, similar to the precious metal-based catalysts. Experimental The GR1 and GR2 precursors were prepared by precipitation of iron salts with NaOH or Na2CO3 at room temperature. After filtration and washing, the precipitates were calcined at 500 oC for 5 h. The NO+CO reaction was conducted in a continuous-flow fixed-bed quartz reactor with a typical feed gas composition of 0.5% CO/0.5% NO/He (36,000 ml.g-1.h-1). Results and discussion Fig. 1 TEM images of the precursors and oxides: a) GR1; b) α-Fe2O3-GR1; c) GR2; d) α-Fe2O3-GR2 Fig. 2 NO+CO performance on α-Fe2O3 The GR1 and GR2 precursors exhibited characteristic diffraction peaks with different interlayer distances in their XRD patterns but similar fibrous-like morphology judged by TEM observations (Fig.1). After calcination, the GR1 precursor yielded fibrous α-Fe2O3, but the GR2 precursor produced α-Fe2O3 nanosheets. The crystal size of the fibrous α-Fe2O3 and the α-Fe2O3 nanosheets are 12.9 nm and 15.7 nm, corresponding to the surface areas of 87 and 54 m2/g, respectively. When used for NO+CO reaction, the fibrous α-Fe2O3 showed a much higher reactivity than the α-Fe2O3 nanosheets. NO conversion over the former was readily 80% even at 400 oC, but it was only 5% over the later. Considering the crystal sizes and surface areas, it is speculated that the morphology, instead of the surface area, dominated the catalytic performance. Additionally, the fibrous α-Fe2O3 was rather stable for NO reduction for 100 h time-on-stream with a NO conversion of 80-90%, which is almost equivalent to the performance of precious metal-based catalysts under similar conditions. Conclusions Fibrous-like α-Fe2O3 was highly active and stable for NO reduction by CO, giving a similar reaction performance to precious metal-based catalysts. The superior reactivity might be resulted from preferential exposure of active sites for NO reduction in the fibrous-like structure. References [1] S. Roy, M.S. Hedge, G. Madras, Appl. Energy 86 (2009) 2283-2297. [2] B.V. Reddy, S. N. Khanna, Phys. Rev. Lett.93 (2004) 068301-4.
Document Type会议论文
Corresponding AuthorShen WJ(申文杰)
Recommended Citation
GB/T 7714
Mou XL,Li Y,Huang XM,et al. Effect of α-Fe2O3 morphology on NO reduction by CO[C],2010:352/2.
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