DICP OpenIR
学科主题物理化学
Synthesis of Iron Oxide Nanorods and Application in NOx Abatement
Mou XL(牟效玲); Wei XJ(魏雪娇); Zhang BS(张炳森); Li Y(李勇); Yao LD(姚立德); Su DS(苏党生); Shen WJ(申文杰)
会议文集abstract of EuropaCat X
会议名称EUROPACAT X
会议日期2011-8-28
2011
会议地点格拉斯哥
其他题名氧化铁纳米棒的制备及在NOx消除中的应用
页码0-0
出版者待补充
出版地待补充
合作性质墙报
部门归属501
主办者格拉斯哥大学
英文摘要Synthesis of Iron Oxide Nanorods and Application in NOx Abatement Xiaoling Mu1, Xuejiao Wei1, Bingsen Zhang2, Yong Li1, Lide Yao2, Dangsheng Su2* and Wenjie Shen1* 1State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, CAS, Zhongshan Road 457, 116023, Dalian, China; 2Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6 14195 Berlin, Germany *email: 1shen98@dicp.ac.cn; 2dangsheng@fhi-berlin.mpg.de Introduction Iron oxides represent an important catalytic material [1]. Fabrication of different shapes and morphologies of Fe2O3 has received much attention in the last two decades. However, it is still a great challenge to synthesize 1D α-Fe2O3 and γ-Fe2O3 nanostructures in large scale under a more facile and environment benign way [2]. In this work, 1D α-Fe2O3 and γ-Fe2O3 nanorods were prepared from the same precursor (β-FeOOH). Applications of the two kinds of materials in selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ammonia and the catalytic reduction of NO by CO showed that the exposing facet had significant effect on catalytic activity. Experimental The β-FeOOH nanorod was prepared by precipitation of iron salts with Na2CO3 at 120 ℃. After filtration and washing, the precipitates were calcined at 500 oC for 5 h to obtain α-Fe2O3 and heated at PEG(400) solution for 24 h to get γ-Fe2O3. The NH3-SCR reaction was conducted in a continuous-flow fixed-bed quartz reactor with a typical feed gas composition of 1000 ppm NO/1000 ppm NH3/3% O2/He (72,000 ml.g-1.h-1) and the NO+CO reaction was conducted with a typical feed gas composition of 0.5% CO/0.5% NO/He (36,000 ml.g-1.h-1) in the same apparatus. Microstructural characterizations of the as-prepared catalysts were recorded on a Titan 80-300 kV with Cs corrector and Transmission Electron Microscopy operated at 300 kV. Results/Discussion Fig. 1 shows the TEM images of the relevant materials. The β-FeOOH nanorods precursor was initially obtained by controlled hydrolysis of ferric salt. The precursor was transformed to α-Fe2O3 nanorods by calcination at 500 oC in air, preferentially exposing the (210) and (001) facets that are rich in iron atoms. When refluxed in PEG at 200 oC, however, γ-Fe2O3 nanorods were produced, and this nanorod was enclosed by (110) and (001) surface facets containing both iron and oxygen atoms. Fig. 1 β-FeOOH (a, b), α-Fe2O3 (c, d) γ-Fe2O3 (e, f). Fig.2 NH3-SCR (a) and NO+CO (b) activities of the Fe2O3 nanorods. These Fe2O3 nanorods were examined for NH3-SCR reaction and both showed very high activities below 300 oC (Fig. 2a). In particular, the γ-Fe2O3 nanorods gave more than 80% NO conversion in a wide temperature range of 180-400 oC, while the selectivity towards N2 was around 97%. When used for NO+CO reaction, the γ-Fe2O3 nanaorods showed a much higher reactivity than the α-Fe2O3 nanorods. NO conversion over the former was readily 70% even at 400 oC, but it was only 15% 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. Temperature-programmed surface reactions and IR measurements indicated that the adsorption and activation of NO on the iron oxide surface is the rate-determining step that was closely associated with the atomic configurations of the exposed planes. The superior performance of the γ-Fe2O3 nanorods was based on the fact that the exposed facets effectively adsorb and activate NO molecule. This finding further emphasizes the importance of morphology control in preparing highly efficient oxide nanocatalysts. References 1. R. Cornell; U. Schwertmann, “The iron oxides”, second completely revised and extended edition, VCH, Weinheim, p. 518, 2003. 2. Y. Piao; J. Kim; H. Na; D. Kim; J. Baek; M. Ko; J. Lee; M. Shokouhimehr; T. Hyeon, Nature Mater., 7, 242 (2008); Synthesis of Iron Oxide Nanorods and Application in NOx Abatement Xiaoling Mu1, Xuejiao Wei1, Bingsen Zhang2, Yong Li1, Lide Yao2, Dangsheng Su2* and Wenjie Shen1* 1State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, CAS, Zhongshan Road 457, 116023, Dalian, China; 2Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6 14195 Berlin, Germany *email: 1shen98@dicp.ac.cn; 2dangsheng@fhi-berlin.mpg.de Introduction Iron oxides represent an important catalytic material [1]. Fabrication of different shapes and morphologies of Fe2O3 has received much attention in the last two decades. However, it is still a great challenge to synthesize 1D α-Fe2O3 and γ-Fe2O3 nanostructures in large scale under a more facile and environment benign way [2]. In this work, 1D α-Fe2O3 and γ-Fe2O3 nanorods were prepared from the same precursor (β-FeOOH). Applications of the two kinds of materials in selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ammonia and the catalytic reduction of NO by CO showed that the exposing facet had significant effect on catalytic activity. Experimental The β-FeOOH nanorod was prepared by precipitation of iron salts with Na2CO3 at 120 ℃. After filtration and washing, the precipitates were calcined at 500 oC for 5 h to obtain α-Fe2O3 and heated at PEG(400) solution for 24 h to get γ-Fe2O3. The NH3-SCR reaction was conducted in a continuous-flow fixed-bed quartz reactor with a typical feed gas composition of 1000 ppm NO/1000 ppm NH3/3% O2/He (72,000 ml.g-1.h-1) and the NO+CO reaction was conducted with a typical feed gas composition of 0.5% CO/0.5% NO/He (36,000 ml.g-1.h-1) in the same apparatus. Microstructural characterizations of the as-prepared catalysts were recorded on a Titan 80-300 kV with Cs corrector and Transmission Electron Microscopy operated at 300 kV. Results/Discussion Fig. 1 shows the TEM images of the relevant materials. The β-FeOOH nanorods precursor was initially obtained by controlled hydrolysis of ferric salt. The precursor was transformed to α-Fe2O3 nanorods by calcination at 500 oC in air, preferentially exposing the (210) and (001) facets that are rich in iron atoms. When refluxed in PEG at 200 oC, however, γ-Fe2O3 nanorods were produced, and this nanorod was enclosed by (110) and (001) surface facets containing both iron and oxygen atoms. Fig. 1 β-FeOOH (a, b), α-Fe2O3 (c, d) γ-Fe2O3 (e, f). Fig.2 NH3-SCR (a) and NO+CO (b) activities of the Fe2O3 nanorods. These Fe2O3 nanorods were examined for NH3-SCR reaction and both showed very high activities below 300 oC (Fig. 2a). In particular, the γ-Fe2O3 nanorods gave more than 80% NO conversion in a wide temperature range of 180-400 oC, while the selectivity towards N2 was around 97%. When used for NO+CO reaction, the γ-Fe2O3 nanaorods showed a much higher reactivity than the α-Fe2O3 nanorods. NO conversion over the former was readily 70% even at 400 oC, but it was only 15% 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. Temperature-programmed surface reactions and IR measurements indicated that the adsorption and activation of NO on the iron oxide surface is the rate-determining step that was closely associated with the atomic configurations of the exposed planes. The superior performance of the γ-Fe2O3 nanorods was based on the fact that the exposed facets effectively adsorb and activate NO molecule. This finding further emphasizes the importance of morphology control in preparing highly efficient oxide nanocatalysts. References 1. R. Cornell; U. Schwertmann, “The iron oxides”, second completely revised and extended edition, VCH, Weinheim, p. 518, 2003. 2. Y. Piao; J. Kim; H. Na; D. Kim; J. Baek; M. Ko; J. Lee; M. Shokouhimehr; T. Hyeon, Nature Mater., 7, 242 (2008)
文献类型会议论文
条目标识符http://cas-ir.dicp.ac.cn/handle/321008/115972
专题中国科学院大连化学物理研究所
通讯作者Shen WJ(申文杰)
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Mou XL,Wei XJ,Zhang BS,et al. Synthesis of Iron Oxide Nanorods and Application in NOx Abatement[C]. 待补充:待补充,2011:0-0.
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