کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
66448 | 48432 | 2010 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts](/preview/png/66448.png)
Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation and flame spray pyrolysis. Addition of a Ce precursor to the FSP catalyst resulted in significantly smaller silver particles. Ce-doped FSP catalysts in general exhibited a superior catalytic performance with TONs up to 2000 except for cumene oxidation that appeared to proceed mainly by homogeneous catalysis. In addition, flame-made catalysts were more stable against silver leaching compared to the impregnated catalysts. The structure of the silver catalysts was studied in detail both by X-ray absorption spectroscopy and transmission electron microscopy suggesting metallic silver to be required for catalytic activity. Catalytic studies point to a radical mechanism which differs depending on the type of substrate.
Flame synthesized and impregnated ceria-doped Ag/SiO2 catalysts effectively catalyze the side-chain oxidation of alkyl aromatic compounds such as toluene, p-xylene, ethylbenzene and cumene.Figure optionsDownload high-quality image (97 K)Download as PowerPoint slide
Journal: Journal of Molecular Catalysis A: Chemical - Volume 331, Issues 1–2, 1 October 2010, Pages 40–49