不同载体对负载型氧化钨催化剂在己二酸合成反应中的结构及性能影响

以SBA-15、六角介孔二氧化硅（HMS）和SnO₂为载体，通过浸渍法合成了含钨负载型催化剂，并考察了三种催化剂在环氧环己烷选择氧化制备己二酸反应中的催化性能. 通过X射线衍射（XRD），透射电镜/场发射透射电镜（TEM/FETEM），紫外-可见漫反射光谱（UV-Vis DRS），拉曼（Raman）光谱，X射线光电子能谱（XPS）以及傅里叶变换红外（FTIR）光谱等手段对各种催化剂的结构进行表征. 结果表明，载体与催化剂的性能有密切的关系. 以SnO₂为载体的WO₃/SnO₂催化剂活性最高，其次是WO₃/HMS催化剂，WO₃/SBA-15 催化剂的活性最差.XRD 分析显示WO₃/SnO₂催化剂中氧化钨物种的晶化程度最低，TEM 和XPS 结果表明氧化钨物种在WO₃/SnO₂催化剂表面高度分散并且粒径尺寸很小（约2 nm），UV-Vis DRS结果表明在WO₃/SnO₂催化剂中存在孤立WO₄]四面体和低聚态的钨物种，这些物种的存在可能是WO₃/SnO₂催化剂具有高活性的主要原因. 此外，WO₃/SnO₂催化剂可以重复使用多次，6 次反应后己二酸（AA）得率仍然保持在80%以上，说明氧化钨物种与SnO₂载体间存在强烈的相互作用，从而提高了催化剂的稳定性.

Effect of Support on the Structural Evolution and Catalytic Performance of WO3-Supported Catalysts in the Synthesis of Adipic Acid

A series of tungsten-based catalysts were synthesized via a traditional impregnation method using SBA-15, hexagonal mesoporous silica (HMS), and SnO₂ as the support. The supported catalysts were characterized by X-ray powder diffraction (XRD), transmission electron microscopy/field-emission transmission electron microscopy (TEM/FETEM), UV-Vis diffuse reflection spectroscopy (UV-Vis DRS), Raman spectrometry, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It was found that the support was crucial to the dispersion and nature of the tungsten species on the catalyst. In this study, the catalytic performances of catalysts with different supports were investigated for the synthesis of adipic acid (AA) from the selective oxidation of cyclohexene oxide. The excellent catalytic performance of the catalyst was obtained over WO₃/SnO₂, followed by WO₃/HMS and WO₃/SBA-15. The XRD results indicate that the degree of crystallinity of the tungsten species of WO₃/SnO₂ catalyst was low and the particle size of WO₃ was small (~2 nm). TEM and XPS results imply a high dispersion of tungsten species on the SnO₂ support. The UV-Vis DRS spectra demonstrate the existence of WO₄] and low-polymeric tungsten species. In addition, the W-based catalyst with SnO₂ as the support could retain high activity, even after being reused six times, suggesting that there is strong interaction between tungsten species and the SnO₂-support that enhanced the stability of the catalyst. This shows the potential of the WO₃/SnO₂ as a catalyst for the synthesis of adipic acid.