Direct synthesis and structural characteristics of ordered SBA-15 mesoporous silica containing tungsten oxides and tungsten carbides

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	Direct synthesis and structural characteristics of ordered SBA-15 mesoporous silica containing tungsten oxides and tungsten carbides
	Song HL(宋焕玲)
刊名	Journal of Physical Chemistry C
	2007
卷号	111 期号:42 页码:15173-15184
ISSN号	1932-7447
通讯作者	季生福
中文摘要	A series of WO3-SBA-15 materials with different Si/W ratios have been hydrothermally synthesized using tetraethyl orthosilicate (TEOS) as silica precursor, ammonium paratungstate as tungsten precursor, and EO20- PO70EO20 (P123) as structure-directing reagent. After temperature-programmed carburization (TPC) in flowing CH4/H2 (20/80 v/v mixture), the materials were converted to the corresponding WxC-SBA-15 materials. The structure of the oxide and carbide materials has been characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), nitrogen adsorption-desorption measurements, 29Si magic-angle spinning (MAS) NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and thermogravimetric and differential scanning calorimetric analysis (TG-DSC) measurements. The results show that after hydrothermal synthesis using different amounts of tungsten and subsequent carburization, the materials retain the mesopore structure of SBA-15. When Si/W ) 30-15, the majority of the tungsten is dispersed in the channels of SBA-15 with the remainder being incorporated into the framework of SBA-15 with the formation of Si-O-W bonds. The tungsten carbide exists as a single W2C phase after carburization. At higher tungsten content (Si/W ) 7.5), the amount of tungsten in the framework of SBA-15 increases with the formation of both Si-O-W bonds and W-O-W bonds. The tungsten carbide formed after carburization exists as a mixture of W2C and WC phases. A model for the distribution of tungsten in SBA-15 is proposed involving three different tungsten species: R-W inside SBA-15 channels, â-W embedded in the internal surfaces of the SBA-15 channels, and ç-W inside the framework of SBA-15. After temperature-programmed carburization, R-W sites are transformed into W2C, whereas â-W sites afford WC; in contrast, ç-W sites show little change after carburization.
学科主题	物理化学
收录类别	SCI
资助信息	the National Natural Science Foundation of China (Grant No. 20473009);the National Basic Research Program of China (973 Program) (Grant No. 2006CB202503)
语种	英语
WOS记录号	WOS:000250438900008
公开日期	2012-11-09
内容类型	期刊论文
源URL	[http://210.77.64.217/handle/362003/1875]
专题	兰州化学物理研究所_OSSO国家重点实验室
推荐引用方式 GB/T 7714	Song HL. Direct synthesis and structural characteristics of ordered SBA-15 mesoporous silica containing tungsten oxides and tungsten carbides[J]. Journal of Physical Chemistry C,2007,111(42):15173-15184.
APA	宋焕玲.(2007).Direct synthesis and structural characteristics of ordered SBA-15 mesoporous silica containing tungsten oxides and tungsten carbides.Journal of Physical Chemistry C,111(42),15173-15184.
MLA	宋焕玲."Direct synthesis and structural characteristics of ordered SBA-15 mesoporous silica containing tungsten oxides and tungsten carbides".Journal of Physical Chemistry C 111.42(2007):15173-15184.