کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
62429 47639 2008 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
In situ solid-state NMR investigations of the vapor-phase Beckmann rearrangement of 15N-cyclohexanone oxime on MFI-type zeolites and mesoporous SBA-15 materials in the absence and presence of the additive 13C-methanol
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
In situ solid-state NMR investigations of the vapor-phase Beckmann rearrangement of 15N-cyclohexanone oxime on MFI-type zeolites and mesoporous SBA-15 materials in the absence and presence of the additive 13C-methanol
چکیده انگلیسی

The stepwise conversion of 15N-cyclohexanone oxime into ε  -caprolactam via the vapor-phase Beckmann rearrangement on silicalite-1 (nSi/nAl=1700nSi/nAl=1700), siliceous SBA-15 (nSi/nAl=1800nSi/nAl=1800), H-ZSM-5 (nSi/nAl=14nSi/nAl=14), and [Al]SBA-15 (nSi/nAl=8.7nSi/nAl=8.7) in the absence and presence of 13C-methanol was investigated by solid-state 15N and 13C CP/MAS NMR spectroscopy. The MFI-type zeolites and SBA-15 materials are characterized by different acid strengths and pore diameters. The surface OH concentrations in silicalite-1, SBA-15, H-ZSM-5, and [Al]SBA-15 materials were determined to 0.31, 2.81, 1.12, and 1.29 mmol g−1, respectively. 1H, 29Si, and 15N MAS NMR measurements revealed that the Brønsted acidic OH groups of H-ZSM-5 and [Al]SBA-15 and the large concentration of Q3 silanol groups (Si(OSi)3OH) in siliceous SBA-15 led to the formation of O-protonated ε-caprolactam. On loading and heating of 15N-cyclohexanone oxime on H-ZSM-5 in the presence of methanol, water was formed via dehydration of methanol into dimethyl ether. These water molecules promoted the conversion of O-protonated ε-caprolactam species into ε-aminocapric acid. In addition, on both silicalite-1 and H-ZSM-5 catalysts, partial conversion of methanol into hydrocarbons, such as isobutane, was observed. Furthermore, isopropylamine was formed on silicalite-1 by the reaction of isobutane and byproducts of the Beckmann rearrangement, such as hydroxylamine. In contrast, no influence and conversion of methanol were found during the Beckmann rearrangement of 15N-cyclohexanone oxime on the mesoporous SBA-15 and [Al]SBA-15 materials.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 257, Issue 1, 1 July 2008, Pages 134–141
نویسندگان
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