| 钠助剂对Fe/SiO_2催化剂结构及其催化甲烷氧化偶联反应性能的影响(英文) |
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| 引用本文： | 张慧,寇元.钠助剂对Fe/SiO_2催化剂结构及其催化甲烷氧化偶联反应性能的影响(英文)[J].天然气化学杂志,2001,10(3):190-195. |
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| 作者姓名： | 张慧 寇元 |
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| 摘 要： | 以二氧化硅担载铁氧化物（１ｗｔ％ Ｆｅ／ＳｉＯ２）为探针，结合ＸＲＤ、ＸＡＮＥＳ以及ＥＸＡＦＳ分析结果首次从表面配位几何的观点讨论了钠助剂对Ｆｅ／ＳｉＯ２催化剂结构及其甲烷氧化偶联反应性能所产生的影响。ＸＲＤ分析表明，Ｆｅ／ＳｉＯ２经８００℃焙烧后仍保持无定形特征，添加钠助剂并经８００℃焙烧后，Ｎ２Ｆｅ／ＳｉＯ２已转化为α－方石英结构。Ｆｅ／ＳｉＯ２的ＥＸＡＦＳ拟合结果显示，铁中心被５个近邻氧环绕，平均Ｆｅ－Ｏ键长为０．１９４ｎｍ。与Ｆｅ／ＳｉＯ２相比，Ｎａ－Ｆｅ／ＳｉＯ２的径向结构函数谱中最强峰的相对强度提高了１／４，表明形成了一个更加密集的Ｆｅ－Ｏ壳层。拟合结果表明围绕中心铁原子０．１８９ｎｍ处平均有４．１个氧近邻。Ｆｅ－Ｋ边ＸＡＮＥＳ谱表明钠的参与使催化剂的活性组分由配位不饱和的八面体位逐渐向四配位四面体位迁移。甲烷氧化偶联反应结果显示，添加钠助剂后甲烷转化率有所下降，但是Ｃ２烃的选择性提高了近４２个百分点，ＣＯｘ的选择性则明显下降。说明钠的引入使催化剂的表面结构发生变化，所形成的多数四面体／少数八面体混合结构有效地抑制了甲烷的深度氧化，乙烯乙烷的选择性明显提高。
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| 关 键 词： | 钠助剂 二氧化硅担载铁催化剂 XANES EXAFS 甲烷氧化偶联 |
EFFECT OF SODIUM PROMOTER ON STRUCTURE AND CATALYTIC PERFORMANCE OF Fe/SiO_2 IN OCM REACTION |
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| Hui Zhang,Yuan Kou.EFFECT OF SODIUM PROMOTER ON STRUCTURE AND CATALYTIC PERFORMANCE OF Fe/SiO_2 IN OCM REACTION[J].Journal of Natural Gas Chemistry,2001,10(3):190-195. |
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| Authors: | Hui Zhang Yuan Kou |
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| Institution: | Key Laboratory of Science & Technology of Controllable Chemical Reaction of Education Ministry Beijing University of Chemical & Technology Beijing 100029 College of Chemistry & Molecular Engineering Beijing University, Beijing 100871 |
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| Abstract: | Silica-supported iron was taken as a probe to explore the effect of sodium promoter on the structure of Fe/SiO2 and its catalytic performance in OCM reaction using XRD, XANES and EXAFS techniques. XRD results indicate that SiO2 support still remains its amorphous feature in 1wt%Fe/SO2 after calcined at 800oC, while a sample promoted with sodium and calcined at 800oC, i.e. 1wt%Na-1wt%Fe/SiO2, is transformed to a-cristobalite structure. |
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| Keywords: | catalysis sodium promoter silica-supported iron XANES EXAFS OCM |
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