丙烯聚合N催化剂制备过程中MgCl_2的溶解和析出机理

通过除去丙烯聚合N催化剂溶解液中的挥发性组分,得到了无水MgCl2与环氧氯丙烷(ECP)和磷酸三丁酯(TBP)形成的络合物MgCl2.ECP.TBP,用XRF技术分析了MgCl2.ECP.TBP中Mg,Cl,P元素的相对含量,从而解释了N催化剂制备过程中MgCl2的溶解过程。用31P NMR和13C NMR技术分析了MgCl2.ECP.TBP与析出剂TiCl4之间的反应,阐述了N催化剂制备过程中MgCl2的析出机理。实验结果表明,在TiCl4的作用下,MgCl2.ECP.TBP中的TBP与TiCl4形成了新的络合物TBP.TiCl4。正是由于TBP和ECP与TiCl4的相互作用使得络合物MgCl2.ECP.TBP解离,从而导致了MgCl2的析出。

Mechanism for MgCl2 Dissolution-Sedimentation in Preparation of N-Catalyst for Propylene Polymerization

The coordination compound MgCl_2·ECP·TBP was obtained through removal of the volatile components in the solution used in preparation of Ziegler-Natta N-catalyst for propylene polymerization,namely the solution of MgCl_2 in toluene,epichlorohydrin(ECP) and tributyl phosphate(TBP).And then the relative contents of element Mg,P and Cl in the coordination compound was analyzed by means of XRF.The result could explain the MgCl_2 dissolving process in the preparation of N-Catalyst.On the other hand,the corresponding sedimentation process was analyzed by means of ～(31)P NMR and ～(13)C NMR.The results indicated that with addition of precipitator TiCl_4,TBP coordinated with TiCl_4 to form the new complex TBP·TiCl_4 and ECP reacted with TiCl_4 to form(2-chloromethyl)chloroethoxytitanium trichlorid and its derivates.Such two reactions led to disassociation of MgCl_2·ECP·TBP and sedimentation of MgCl_2.