Coordination structures of vanadium and iron in MCM-41 and the catalytic properties in partial oxidation of methane
发布日期
2004-11作者
Qinghong Zhang
张庆红
Wei Yang
Xiaoxing Wang
Ye Wang
王野
Tetsuya Shishido
Katsuomi Takehira
所在专题
- 化学化工-已发表论文 [14469]
摘要
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 1 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 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. (C) 2004 Elsevier Inc. All rights reserved.
出处
MICROPOROUS AND MESOPOROUS MATERIALS,2005,77(2-3):223-234本条目访问地址(URI)
http://dx.doi.org/doi:10.1016/j.micromeso.2004.09.006https://dspace.xmu.edu.cn/handle/2288/11273