文献类型：期刊文献

英文题名：Surface analytical approach to TiCl3-based Ziegler-Natta catalysts combined with microstructure analysis of polymer

作者：Hasan, A.T.M. Kamrul[1]; Fang, Y.[2]; Liu, Boping[2]; Terano, Minoru[3]

机构：[1] Chemical Engineering Laboratory, Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi-6205, Bangladesh; [2] State Key Lab. of Chemical Engineering, East China University of Science and Technology, Mei Long Road, 130, Shanghai, P. C. 200237, China; [3] School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan

年份：2010

卷号：51

期号：16

起止页码：3627

外文期刊名：Polymer

收录：EI(收录号：20103513192887)

语种：英文

外文关键词：Magic angle spinning - Particle size - Microstructure - Nuclear magnetic resonance spectroscopy - Catalyst activity - X ray photoelectron spectroscopy - Aluminum - Particle size analysis

摘要：In the field of Ziegler-Natta catalysis (ZNC), most of the previous works have been focused on the characterization of either catalyst surface or polymer microstructure but the combined studies of these two aspects are still limited. A clearer understanding concerning the isospecific nature of active sites on the donor-free TiCl3 - based catalyst has been presented in this work in terms of both surface characteristics of the catalyst and microstructure of polypropylene (PP) produced. Ti- and Al-species existing in the catalyst surface have been identified by high resolution X-ray photoelectron spectroscopic (XPS) and solid-state magic angle spinning nuclear magnetic resonance (27Al MAS NMR) techniques, respectively. Moreover, grinding effect on catalyst performance has been carried out to investigate the nature of active sites by particle size distribution (PSD) method. Microstructures of PPs produced using the surface characterized catalysts have been investigated by temperature rising elution fractionation (TREF), 13C NMR and GPC methods. It can be demonstrated that the surface structure of catalyst is dominantly affected by the type of Al-alkyl cocatalyst used as well as the preparation method of catalyst whilst it precisely determine the nature of isospecificity of active sites and its distribution. Two different types of surface Ti+3-species have been identified on the catalyst surface depending on the different vacant coordination states of surface titanium species. On the other hand, 27Al MAS NMR experiments have shown the presence of surface aluminum in four (AlIV), five (AlV) and six (AlVI) coordination number of multiple environments. The states of surface Al-species are sensitive to coordination number and symmetry of the local environment around the aluminum nuclei. Higher isospecificity of active sites is seen to be related to the higher fulfilled coordinated states of surface Ti- and Al-species. ? 2010 Elsevier Ltd.