摘要
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。
SiO2/MgCl2.xBu（OH）2/poly（styrene-co-acrylic acid） inorganic/organic hybrid support was synthesized and was of three types of chemical environments：inorganic support SiO2,MgCl2.xBu（OH）2 adduct and organic support PSA.TiCl4 was immobilized on the hybrid support.The influences of its composition on the titanium content,catalyst morphology and performance in ethylene polymerizations were also investigated.The results showed that titanium content decreased sharply when PSA was added to the hybrid support.The kinetic study of ethylene/1-hexene copolymerization indicated that there was a long period of diffusion-controlled induction time at the initial stage for the hybrid catalysts,due to the barrier effect from PSA,comparing with SiO2/MgCl2.xBu（OH）2/TiCl4 that had no induction time in ethylene polymerization.As the content of PSA increased,the induction time extended and almost no decay happened until the end of the polymerization.Moreover,the polyethylene produced by Si O2/MgCl2.xBu（OH）2/PSA/TiCl4was of broader molecular weight distribution（MWD） and high melt flowratio.Based on its morphological features showed by SEM,the polymerization mechanism of the hybrid catalysts was also investigated.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2010年第12期3107-3116,共10页
CIESC Journal
基金
国家自然科学基金项目(20776124)
国家高技术研究发展计划项目(2007AA030208)
中央高校基本科研业务费专项资金(2009QNA4028)~~
