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利用EPR法研究了MgCl_2-n-BuOH-SiCl_4-TiCl_4/Al(i-Bu)_3体系催化剂中钛离子的状态,发现催化剂体系中存在(Ⅰ)、(Ⅱ)、(Ⅲ)和(Ⅳ)四种类型的Ti~(3+)离子的顺磁物类,其EPR信号分别为g=1.99,g_Δ=1.97,g_Δ=1.95和g_Δ=1.88,前三者为处于不同畸变配体场中的非烷基化Ti~(3+)离子,在烯烃聚合中不起活性中心作用.带有Cl空配位的烷基化Ti~(3+)离子是活性的物类,但其中只有少部分呈弧立状态的(Ⅳ)型离子对EPR有贡献,大部分可能通过氯桥键合,在MgCl_2表面上形成聚集体或TiCl_3分散粒子而成为EPR无声的物类.
The state of titanium ions in MgCl_2-n-BuOH-SiCl_4-TiCl_4 / Al (i-Bu) _3 system catalyst was studied by EPR method. It was found that there are (Ⅰ), (Ⅱ), The four types of paramagnetic species with Ti ~ (3 +) ions showed EPR signals of g = 1.99, g_Δ = 1.97, g_Δ = 1.95 and g_Δ = 1.88, respectively. Non-alkylated Ti ~ (3+) ions can not play an active role in the polymerization of olefins. Alkylated Ti ~ (3+) ions with Cl vacancies are active species, but only a few (IV) ions in the arc state contribute to the EPR, and most of them may form the silencers of EPR through the formation of aggregates or TiCl_3 dispersed particles on the surface of MgCl_2 by chlorine bridge bonding.