Propene polymerization on titanium-magnesium catalysts, 4. ESR study of TI3+ ions†
Propene polymerization on titanium-magnesium catalysts, 4. ESR study of TI3+ ions†
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钛镁催化剂上的丙烯聚合，4. TI3+ 离子的 ESR 研究†
DOI：
10.1002/macp.1986.021870201
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发表时间：
1986
影响因子：
2.5
通讯作者：
G. D. Bukatov
中科院分区：
文献类型：
--
作者：
S. Sergeev;V. A. Poluboyarov;V. Zakharov;V. F. Anufrienko;G. D. Bukatov
用ESR法研究了Ti3+离子在不同组成的钛镁催化剂TiCl4/MgCl2 + AlR3、TiCl4/MgCl2 + Al(i-Bu)3 + EB、TiCl4/EB/MgCl2 + Al(i-Bu)3 + EB中的作用。比较了ESR数据和催化性能。结果表明，苯甲酸乙酯（EB）的引入增加了固体催化剂的立体专一性，使ESR能观察到的Ti3+离子的比例显著增加，在ESR光谱中出现了几个新的信号，并使固体催化剂与有机铝共催化剂相互作用过程中从溶液中去除的钛的比例增加。钛离子主要存在于粒子或表面缔合物中，其Ti3+离子在ESR光谱中不产生信号，ESR观察到的Ti3+离子为非活性聚合中心。活性中心似乎位于MgCl2表面形成的高度分散的TiCl3颗粒或表面缔合物中，而在ESR光谱中没有显示出来。在EB存在下增加立体特异性被认为是由苯甲酸乙酯使非立体特异性活性中心失活引起的。
The role of Ti3+ ions in titanium-magnesium catalysts of various composition, TiCl4/MgCl2 + AlR3, TiCl4/MgCl2 + Al(i-Bu)3 + EB, TiCl4/EB/MgCl2 + Al(i-Bu)3 and TiCl4/EB/MgCl2 + Al(i-Bu)3 + EB, was studied by means of ESR. The ESR data and the catalytic properties were compared. It could be shown that the introduction of ethyl benzoate (EB) leads to an increase of stereospecificity, to a considerable increase of the portion of Ti3+ ions which can be observed by ESR, to the appearance of several new signals in the ESR spectra and to an increase of the portion of titanium in solution, removed from the solid catalyst during the interaction with the organoaluminium cocatalyst. Titanium ions are found mainly in the particles or surface associates whose Ti3+ ions produce no signals in the ESR spectra, Ti3+ ions observed by ESR are found to be inactive centers of polymerization. The active centers appear to be localized in highly dispersed particles or surface associates of TiCl3, formed on the MgCl2 surface and are not revealed in the ESR spectra. Increasing stereospecificity in the presence of EB is assumed to be caused by deactivation of non-stereospecific active centers with ethyl benzoate.