National Changhua University of Education Institutional Repository : Item 987654321/16853
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 6491/11663
造访人次 : 24648601      在线人数 : 41
RC Version 3.2 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜寻范围 进阶搜寻

jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://ir.ncue.edu.tw/ir/handle/987654321/16853

题名: Effects of Interfacial Charge and the Particle Size of Titanate Nanotube-Supported Pt Nanoparticles on the Hydrogenation of Cinnamaldehyde
作者: Chiu, Tsai-Chin;Lee, Hsin-Yi;Li, Pei-Hua;Chao, Jiunn-Hsing;Lin, Chiu-Hsun
贡献者: 化學系
日期: 2013-03
上传时间: 2013-06-05T09:36:44Z
出版者: IOP Publishing Ltd.
摘要: The oxidation state and size of Pt nanoparticles attached to alkali metal titanate nanotubes (MTNTs=M2Ti3O7, M = Li +, Na+, K+, Cs+) via ion exchange (indicated by the added label '-IE') and wet impregnation (indicated by the added label '-IMP') methods varied systematically with the cation of the MTNTs. X-ray photoelectron spectroscopy revealed that the binding energy of Pt was reduced to a low value when the support was changed from LiTNTs to CsTNTs, yielding a Ptδ- oxidation state. Thus, a space charge layer (SCL) was constructed at the interface between the Pt particle and MTNT support; the former carried the negative charge, and the alkali cation and proton in the hydroxyl group of the latter carried the positive charge. Due to a higher M/Ti atomic ratio in MTNTs, a higher electron density accumulated on Pt particles in Pt/MTNTs-IMP than on those in Pt/MTNTs-IE. Sub-ambient temperature temperature-programmed reduction and transmission electron microscopy revealed that because of the difference in reducibility of PtOx/MTNTs, the mean Pt particle size followed the order Pt/CsTNTs > Pt/KTNTs > Pt/NaTNTs > Pt/LiTNTs and Pt/MTNTs-IMP > Pt/MTNTs-IE. DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) showed that owing to its interaction with SCL, cinnamaldehyde adsorbed on Pt mainly through the C=C bond at the Pt-MTNT interfaces, and the small Pt particles in Pt/LiTNTs adsorbed three times more cinnamaldehyde than those in Pt/CsTNTs. Due to the competition between the adsorption of cinnamaldehyde and C=C activation, Pt/KTNT-IMP is the most active Pt/MTNT catalysts, achieving a conversion of 100% in the hydrogenation of cinnamaldehyde at 2 atm and 313 K. The carbonyl stretching of adsorbed cinnamaldehyde was almost unperturbed by adsorption (at 1705 cm-1), suggesting that Ptδ- and the π electrons in the carbonyl group repel each other, so the CH=O group points upward and away from the Pt surface, preventing it from being hydrogenated and causing Pt/MTNTs to exhibit high 3-phenyl propionaldehyde selectivities of 75-80%.
關聯: Nanotechnology, 24(11): 115601
显示于类别:[化學系] 期刊論文

文件中的档案:

档案 大小格式浏览次数
index.html0KbHTML586检视/开启


在NCUEIR中所有的数据项都受到原著作权保护.

 


DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回馈