球形TiCl_4/MgCl_2催化剂催化丙烯聚合

以乳化急冷法制备的球形M gC l2为载体,制备了球形T iC l4/M gC l2催化剂(简称催化剂),并将该催化剂用于丙烯聚合。采用扫描电子显微镜、N2吸附法对催化剂及聚合物的形态进行了表征,考察了聚合时间、聚合温度、铝钛比、铝硅比、氢气加入量对催化剂性能的影响。实验结果表明,催化剂与聚合物均为球形,且催化剂粒径分布窄,具有较大的孔体积和孔径,所制得的聚丙烯也具有孔隙率大、孔径大等特点。较佳的聚合条件为:聚合温度70~75℃、聚合时间3h、铝与钛摩尔比为300、铝与硅摩尔比为15、氢气加入量(质量分数)2.00×10-4;在此条件下,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规度;催化剂具有良好的氢调敏感性。

Polymerization of Propylene on TiCl4/MgCl2 Spherical Catalyst

A novel TiCl_4/MgCl_2 supported catalyst was prepared by emulsifying and quenching.Batch polymerization of propylene on TiCl_4/MgCl_2 catalyst was investigated.Morphologies and characteristics of TiCl_4/MgCl_2 catalyst and polymer obtained were studied by means of SEM,N_2 adsorption and mercury injection method.Effects of polymerization time,polymerization temperature,n(Al) ∶n(Ti),(n(Al) ∶)n(Si)and H_2 addition on catalyst performance were discussed.Catalyst was spherical in form with narrow particle diameter distribution,big pore volume and big pore size.The produced polypropylene also was high in porosity and good in pore structure.By prolonging polymerization time,isotacticity and bulk density of polypropylene increased,while catalyst activity firstly rose and then dropped off(some what.)By raising polymerization temperature,catalyst activity and polypropylene isotacticity increased.High catalytic activity and polypropylene isotacticity could be obtained under optimal conditions: polymerization temperature 70-75℃,polymerization time 3h,(n(Al))∶ n(Ti)=300,(n(Al) ∶)n(Si)=15,and w(H_2)=2.00×10~(-4).The catalyst showed good sensitivity to hydrogen.