丙烯聚合N催化剂制备过程中MgCl_2的溶解和析出机理

Mechanism for MgCl_2 Dissolution-Sedimentation in Preparation of N-Catalyst for Propylene Polymerization

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。

The coordination compound MgCl2·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 MgCl2 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 MgCl2 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 TiCl4,TBP coordinated with TiCl4 to form the new complex TBP·TiCl4 and ECP reacted with TiCl4 to form（2-chloromethyl）chloroethoxytitanium trichlorid and its derivates.Such two reactions led to disassociation of MgCl2·ECP·TBP and sedimentation of MgCl2.