Synthesis of cerium-doped MCM-48 molecular sieves and its catalytic performance for selective oxidation of cyclohexane
来源期刊：JOURNAL OF RARE EARTHS2008年第4期
论文作者：WANG Yunsong ZHAN Wangcheng GUO Yun GUO Yanglong WANG Yanqin ZHANG Zhigang LIU Xiaohui LU Guanzhong
Key words：Ce-doped MCM-48; synthesis; cyclohexane; catalytic oxidation; rare earths;
Abstract: Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Raman spectroscopy. The results showed that all the samples held the structure of MCM-48, and Ce could enter the framework of MCM-48. However, when Ce/Si molar ratio in the samples was high (0.04 or 0.059), there were CeO2 crystallites as secondary phase in the extraframework of MCM-48. Ce-doped MCM-48 was a very efficient catalyst for the oxidation of cyclohexane in a solvent-free system with oxygen as an oxidant. In the conditions of 0.5 MPa O2 and 413 K for 5 h, the conversion of cyclohexane was 8.1% over Ce-MCM-48-0.02, the total selectivity of cyclohexanol and cyclohaxnone was 98.7%. With an increase of Ce content, the conversion of cyclohexane and the selectivity to cyclohexanol decreased somewhat, but the selectivity to cyclohexanone increased.
WANG Yunsong1，ZHAN Wangcheng1，GUO Yun1，GUO Yanglong1，WANG Yanqin1，ZHANG Zhigang1，LIU Xiaohui1，LU Guanzhong1
(1.Lab for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237, China)
Abstract:Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Raman spectroscopy. The results showed that all the samples held the structure of MCM-48, and Ce could enter the framework of MCM-48. However, when Ce/Si molar ratio in the samples was high (0.04 or 0.059), there were CeO2 crystallites as secondary phase in the extraframework of MCM-48. Ce-doped MCM-48 was a very efficient catalyst for the oxidation of cyclohexane in a solvent-free system with oxygen as an oxidant. In the conditions of 0.5 MPa O2 and 413 K for 5 h, the conversion of cyclohexane was 8.1% over Ce-MCM-48-0.02, the total selectivity of cyclohexanol and cyclohaxnone was 98.7%. With an increase of Ce content, the conversion of cyclohexane and the selectivity to cyclohexanol decreased somewhat, but the selectivity to cyclohexanone increased.
Key words:Ce-doped MCM-48; synthesis; cyclohexane; catalytic oxidation; rare earths;
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