镁钛系载体催化剂乙丙共聚的ESR研究

本文用ESR研究MgCL₂-n-BuOH-i-Bu₃Al-TiCl₄/i-Bu₃Al催化剂乙丙共聚机理。ESR谱表明烷基化Ti³⁺活性中心有单空配位和双空配位两种状态,在乙烯或乙丙烯混和单体存在下ESR谱变化指出g=1.954和g=1.941的共振吸收峰和活性中心有关。结合共聚产物组成及竞聚率的¹³C-NMR谱分析,提出镁钛系载体催化剂活性中心上乙丙同时配位的机理。

ESR STUDIES OF HIGH ACTIVITY TITANIUM-MAGNESIUM CATALYST FOR ETHYLENE AND PROPYLENE COPOLYMERIZATION

ESR method has been used to study the active center states of high yield MgCl2-n-BuOH-i-Bu3Al-TiCl4 catalyst for ethylene and propylene copolymerization. It has been shown that two kinds of coordination states with one and two vacant sites would exist in the alkylated Ti3- ions. The variation of ESR spectra of the catalysts in the presence of ethylene or ethylene and propylene mixture gases show that the ESR signals with g=1.954 and g=1.941 were associated with active centers of Ti3-. Combining with the 13C NMR studies on the composition of copolymerization products and the reactivity ratios, a mechanism for ethylene and propylene simultaneous coordination with active centers of Ti3- in the catalyst has been proposed.