Catalytic oxidation of n-octane over cobalt substituted ceria (Ce0.90Co0.10O2−δ) catalysts
Catalytic oxidation of n-octane over cobalt substituted ceria (Ce0.90Co0.10O2−δ) catalysts
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DOI：
10.1016/j.apcata.2012.09.013
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发表时间：
2012-12
影响因子：
5.5
通讯作者：
M. Narayanappa;V. Dasireddy;H. Friedrich
中科院分区：
文献类型：
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作者：
M. Narayanappa;V. Dasireddy;H. Friedrich
以Ce1−xCoxO2−δ(Ce0.90Co0.10O2−δ)为催化剂，研究了Co取代CeO2对辛烷的催化氧化活化作用。采用溶液燃烧法制备了催化剂，并用BET、粉末X射线衍射仪、结构细化和XPS对催化剂的表面性质进行了表征。所合成的催化剂为萤石结构，其结晶度通过透射电子显微镜的亮场图像得到了证实。吸氢研究表明，在425℃处有一个很强的还原峰，这证明了钴离子在晶格体系的基质中被取代。X射线光电子能谱(XPS)表明，即使在还原条件下，由于Ce和Co离子的标准还原电位顺序，Ce离子也被轻微氧化。在GHSV4000h−-1连续流动固定床反应器中，考察了正辛烷与氧摩尔比为1：0.5~1：2.5时催化剂的催化活性。结果表明，正辛烷产物(烯烃、含氧物、芳烃、碳氧化物和裂解产物)的转化率和选择性随正辛烷与氧摩尔比的变化而变化。测定了C80产品、芳烃、含氧化合物和辛烯在等转化时的产物选择性。催化剂的活性随正辛烷与氧的摩尔比和反应温度的增加而提高。
Catalytic oxidative activation of octane was carried out in the presence of Co substituted ceria catalysts of the type Ce1−xCoxO2−δ(Ce0.90Co0.10O2−δ). The catalysts were synthesized by the solution combustion method and the surface characteristics were determined by BET, powder XRD, structural refinement and XPS. The synthesized catalyst crystallizes with a fluorite structure, the crystallinity was confirmed by bright-field images of TEM. Hydrogen uptake studies show a strong reduction peak at 425°C and it proves substitution of cobalt ions inside the matrix of the lattice system. X-ray photoelectron spectroscopy (XPS) clarified that even though under reduction conditions, the cerium ions were slightly oxidized because of the sequence of standard reduction potentials of both cerium and cobalt ions. The catalytic activity of the catalyst was investigated between the temperature range from 350 to 550°C, in a continuous flow fixed bed reactor at GHSV 4000h−1with varying n-octane to oxygen molar ratios from 1:0.5 to 1:2.5. Results show that the conversion and selectivity of products (alkenes, oxygenates, aromatics, carbon oxides and cracked products) from the n-octane varies consequently with n-octane to oxygen molar ratio. The product selectivity at iso-conversion for C8products, aromatics, oxygenates and octenes was determined. The catalyst shows higher activity with respect to an increase in the n-octane to oxygen molar ratio and reaction temperature.