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题名: Investigation of the Structure and Active Sites of TiO2 Nanorod Supported VOx Catalysts by High-Field and Fast-Spinning V-51 MAS NMR
作者: Hu, Jian Zhi1, 2;  Xu, Suochang1, 2, 3;  Li, Wei-Zhen1, 2;  Hu, Mary Y.1, 2;  Deng, Xuchu1, 2;  Dixon, David A.4;  Vasiliu, Monica4;  Craciun, Raluca4;  Wang, Yong1, 2, 5;  Bao, Xinhe3;  Peden, Charles H. F.1, 2
关键词: V-51 MAS NMR ;  chemical shift calculation ;  surface structure ;  catalytic active sites ;  NMR visibility of vanadium ;  methanol oxidative dehydrogenation reaction
刊名: ACS CATALYSIS
发表日期: 2015-07-01
DOI: 10.1021/acscatal.5b00286
卷: 5, 期:7, 页:3945-3952
收录类别: SCI
文章类型: Article
WOS标题词: Science & Technology ;  Physical Sciences
类目[WOS]: Chemistry, Physical
研究领域[WOS]: Chemistry
英文摘要: Supported VOx/TiO2-rod catalysts were studied by V-51 MAS NMR at high field using a sample spinning rate of 55 kHz. The superior spectral resolution allows for the observation of at least five vanadate species. The assignment of these vanadate species was carried out by quantum chemical calculations of V-51 NMR chemical shifts of model V surface structures. Methanol oxidative dehydrogenation (ODH) was used to establish a correlation between catalytic activity and the various surface V sites. It is found that monomeric V species are predominant at low vanadium loadings with two V-51 NMR peaks observed at about -502 and -529 ppm. V dimers with two bridged oxygens result in a peak at about -555 ppm. Vanadate dimers and polyvanadates connected by one bridged oxygen atom between two adjacent V atoms resonate at about -630 ppm. A positive correlation is found between the V dimers, giving rise to the -555 ppm peak, and the ODH rate, and an even better correlation is obtained by including V monomer contributions. This result suggests that surface V dimers related to the -555 ppm peak and monomers are the primary active sites for the methanol ODH reaction. Furthermore, a portion of the V species is found to be invisible to NMR and the level of such invisibility increases with decreasing V loading levels, suggesting the existence of paramagnetic V species at the surface. These paramagnetic V species are also found to be much less active in methanol ODH.
关键词[WOS]: VANADIUM-OXIDE CATALYSTS ;  DENSITY-FUNCTIONAL THEORY ;  OXIDATIVE DEHYDROGENATION ;  SELECTIVE OXIDATION ;  TITANIA CATALYSTS ;  ANATASE TIO2 ;  SPECTROSCOPY ;  REACTIVITY ;  REDUCTION ;  COMPLEXES
语种: 英语
WOS记录号: WOS:000357626800006
Citation statistics: 
内容类型: 期刊论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/146400
Appears in Collections:中国科学院大连化学物理研究所_期刊论文

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作者单位: 1.Pacific NW Natl Lab, Inst Integrated Catalysis, Richland, WA 99354 USA
2.Pacific NW Natl Lab, Fundamental & Computat Sci Directorate, Richland, WA 99354 USA
3.Chinese Acad Sci, Dalian Inst Chem Phys, Dalian 116023, Peoples R China
4.Univ Alabama, Dept Chem, Tuscaloosa, AL 35487 USA
5.Washington State Univ, Voiland Sch Chem Engn & Bioengn, Pullman, WA 99163 USA

Recommended Citation:
Hu, Jian Zhi,Xu, Suochang,Li, Wei-Zhen,et al. Investigation of the Structure and Active Sites of TiO2 Nanorod Supported VOx Catalysts by High-Field and Fast-Spinning V-51 MAS NMR[J]. ACS CATALYSIS,2015,5(7):3945-3952.
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