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采用SiO2、MgCl2以及苯乙烯-丙烯酸共聚物(PSA)合成了SiO2/MgCl2.xBu(OH)2/PSA无机/有机复合载体并负载TiCl4,得到具有SiO2无机支撑层、MgCl2.xBu(OH)2加合物以及PSA有机载体3种化学环境的SiO2/MgCl2.xBu(OH)2/PSA/TiCl4复合载体负载催化剂。研究了复合载体组成对催化剂的载钛量、形貌以及乙烯聚合行为的影响。当PSA存在时,催化剂的载钛量明显降低。乙烯/1-己烯共聚的反应动力学结果表明,与SiO2/MgCl2.xBu(OH)2/TiCl4相比,无机/有机复合载体负载催化剂的动力学曲线具有一段较长的受扩散控制的诱导期,并且随着PSA质量分数的增加,诱导期延长,动力学曲线由衰减型转变为上升-稳定型。由于复合载体具有多种化学环境,使得负载催化剂活性中心种类增多,共聚性能提高,聚乙烯产品分子量分布变宽,熔流比显著提高。根据聚乙烯树脂的扫描电镜照片,探讨了复合载体负载催化剂在聚乙烯生长过程中的破碎机理。
The SiO2 / MgCl2.xBu (OH) 2 / PSA inorganic / organic composite support was synthesized and supported on TiCl4 using SiO2, MgCl2 and styrene-acrylic acid copolymer (PSA) Adduct, and SiO2 / MgCl2.xBu (OH) 2 / PSA / TiCl4 composite supported catalyst supported on three chemical environments of PSA organic carrier. The effects of the composition of the composite support on the titanium loading, the morphology and the polymerization behavior of ethylene were investigated. When the PSA is present, the amount of titanium supported on the catalyst is significantly reduced. The kinetic results of the ethylene / 1-hexene copolymerization showed that the kinetic curves of the supported catalysts for inorganic / organic composite supports have a longer diffusion-controlled induction compared to SiO2 / MgCl2.xBu (OH) 2 / TiCl4 Period, and with the increase of PSA mass fraction, the induction period was prolonged, and the kinetic curve changed from decay type to ascending - stable type. Due to the multiple chemical environment of the composite supporter, the types of supported catalyst active centers increase, the copolymerization performance increases, the molecular weight distribution of polyethylene products becomes wider, and the melt flow ratio increases significantly. According to the SEM images of the polyethylene resin, the mechanism of the catalyst cracking during the growth of polyethylene was discussed.