苯氧基氯化钛载体型催化体系中不同配体对丙烯聚合活性的影响

EFFECTS OF VARIOUS LIGANDS AROUND THE SUPPORTED CATALYST OF ARYL TITANNIUM CHLORIDE ON THE CATALYTIC ACTIVITY OF THE POLYMERIZATION OF PROPYLENE

配位体是催化剂的重要组成部分,对催化剂的活性,选择性及反应机理都有重要的影响。用不同的配位体来调变齐格勒-纳塔催化剂性能的工作已有一些报道,但研究的角度不尽相同、结论也不完全一致。

The effects of different ligands on the catalytic activity of the propykne polymerization catalyzed by o-XC6H4OTiCl3/MgCl2-EB systems (where X =-CH3, -H,-Cl and -NO2 respectively; EB stands for ethyl benzoate) were studied. It was found that the pKa value of o-XC6H4OH is greafer, the catalytic activity of corresponding catalytic system is higher. The reduction rate of o-CH3C6H5OTiCl3 is faster than that of o-ClC6H5OTiCl3 by AlEt3 Thus, it leads to a higher initial concentration of the active center in O-CH3C6H5OTiCl3/. MgCl2-EB than that in o-ClC6H4OTiCl3/MgCl2-EB system. Using tritiated alcohol quenching method, the concentrations of active center and the rate constants of propagation in above systems were also evaluated. The results obtained were consistent with the conclusions before mentioned.