Synthesis, characterization and catalytic application of mesoporous W-MCM-48 for the selective oxidation of cyclopentene to glutaraldehyde
Synthesis, characterization and catalytic application of mesoporous W-MCM-48 for the selective oxidation of cyclopentene to glutaraldehyde
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DOI：
10.1016/j.molcata.2005.07.025
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发表时间：
2005-11
影响因子：
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通讯作者：
Xinli Yang;W. Dai;R. Gao;Hui Chen;Hexing Li;Yong Cao;Kangnian Fan
中科院分区：
文献类型：
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作者：
Xinli Yang;W. Dai;R. Gao;Hui Chen;Hexing Li;Yong Cao;Kangnian Fan
采用水热法通过调节pH合成了含钨有序MCM-48，并利用X射线衍射（XRD）、N2吸附、透射电镜（TEM）、扫描电镜（SEM）、激光拉曼光谱（Raman）、紫外-可见漫反射光谱（UV-vis漫反射光谱）等分析和光谱技术对其进行了表征（UV-vis DRS）、傅里叶变换红外光谱（FT-IR）和氨程序升温脱附（NH3-TPD）。XRD和FT-IR结果表明，钨取代了MCM-48的硅酸盐骨架结构。TEM和SEM研究证实了新型W-MCM-48材料中存在有序的立方结构。NH3-TPD和FT-IR-吡啶吸附实验表明，在介孔MCM-48骨架中引入钨后，形成了强的Brønsted和刘易斯酸中心，W-MCM-48的中等强酸性有利于其良好的催化性能。所合成的W-MCM-48材料作为非均相催化剂，在环境友好的H2 O2水溶液氧化环戊烯（CPE）制备戊二醛（GA）的反应中表现出很高的活性。当WO 3含量达到20wt%时，钨物种可以稳定存在于MCM-48的硅基基质中。适当的钨物种含量和钨物种的高度分散性是其高活性的原因。20 wt % W-MCM-48催化剂的CPE转化率为85.2%，GA收率为66.9%。此外，几乎没有钨物种被浸出到反应溶液中，使得该催化剂成为其在工业上进一步应用的有希望的候选者。
Tungsten-containing ordered MCM-48 has been synthesized under hydrothermal conditions via pH adjustment and characterized with various analytical and spectroscopic techniques including X-ray diffraction (XRD), N2adsorption, transmission electron micrographs (TEM), scanning electron micrographs (SEM), Laser-Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Fourier-transform infrared spectroscopy (FT-IR) and ammonia temperature-programmed desorption (NH3-TPD). XRD and FT-IR results indicate that the substitution of tungsten occurs in the silicate framework structure of MCM-48. TEM and SEM investigations confirm the presence of ordered cubic structure in the novel W-MCM-48 material. NH3-TPD and FT-IR-pyridine adsorption experiments indicate that the strong Brønsted and Lewis acid sites are formed upon incorporation of tungsten in the mesoporous MCM48 framework and the moderately strong acidity of the W-MCM-48 catalyst is beneficial to its good catalytic performance. The as-synthesized W-MCM-48 material is very active as a heterogeneous catalyst for the selective oxidation of cyclopentene (CPE) to glutaraldehyde (GA) with environmentally benign aqueous hydrogen peroxide as the oxidant. Tungsten species could stably exist in the silica-based matrix of MCM-48 up to WO3content of 20wt%. Both the proper content of tungsten species and its high dispersion account for its high activity. The 20wt% W-MCM-48 catalyst shows CPE conversion of 85.2% and GA yield of 66.9%, respectively. Furthermore, almost no tungsten species are leached into the reaction solution, enabling the catalyst to be a promising candidate for its further application in industry.