کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9617862 | 49182 | 2005 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Coordination structures of vanadium and iron in MCM-41 and the catalytic properties in partial oxidation of methane
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The coordination structures of vanadium and iron introduced into MCM-41, a typical mesoporous silica, by both direct hydrothermal synthesis (DHT) and template-ion exchange (TIE) methods have been studied by X-ray absorption spectroscopy (XANES and EXAFS). Vanadium is tetrahedrally coordinated with oxygen in V-MCM-41 prepared by both methods but the location of vanadium is probably different; vanadium is mainly incorporated inside the framework of MCM-41 by the DHT method as the content is lower than approximately 1Â wt%, while the vanadyl tetrahedra are probably dispersed on the wall surface of MCM-41 over the samples by the TIE method. In the case of Fe-MCM-41, the DHT method results in iron atoms mainly in tetrahedral coordination and isolated from each other in the framework of MCM-41. However, aggregated iron oxides with iron in octahedral coordination are mainly observed in the TIE samples. The V-MCM-41 by the TIE method shows better catalytic performances than that by the DHT method in the partial oxidation of methane to formaldehyde with oxygen. However, the Fe-MCM-41 by the DHT method exhibits remarkably higher methane conversion and formaldehyde selectivity than that by the TIE method.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Microporous and Mesoporous Materials - Volume 77, Issues 2â3, 26 January 2005, Pages 223-234
Journal: Microporous and Mesoporous Materials - Volume 77, Issues 2â3, 26 January 2005, Pages 223-234
نویسندگان
Qinghong Zhang, Wei Yang, Xiaoxing Wang, Ye Wang, Tetsuya Shishido, Katsuomi Takehira,