利用rac-Et（Ind）2ZrCl2、（CH3）2SiCp2ZrCl2和CpZrCl3分别与Al（i-Bu）3组成的催化体系对乙烯齐聚反应进行了研究。考察了反应条件如压力、温度及铝锆比对催化性能的影响。研究结果表明,三种锆系茂金属对齐聚反应的催化活性顺序为rac-Et（Ind）2ZrCl2〉CpZrCl3〉（CH3）2SiCp2ZrCl2,对α-烯烃的选择性顺序为CpZrCl3rac-Et（Ind）2ZrCl2〉（CH3）2SiCp2ZrCl2。还研究了以rac-Et（Ind）2ZrCl2为主催化剂时,助催化剂AlR3-nCln（Al（i-Bu）3,AlEt2Cl和AlEt3）对乙烯齐聚的影响,发现以AlEt2Cl为助催化剂的体系对α-烯烃的选择性高于以Al（i-Bu）3或AlEt3为助催化剂。同时,反应压力对乙烯齐聚有很大影响;α-烯烃的选择性随温度的升高不断提高,且在较高铝锆比下,齐聚产物中α-烯烃含量较多。
Three kinds of metallocene rac-Et（ Ind）2ZrC12, （CH3）2SiCp2ZrC12 and CpZrC13 respectively combined with Al （i-Bu）3 have been employed to the ethylene oligomerization under different reaction pressure, temperature, and Al/Zr molar ratio. The effect of Al（ i-Bu）3, AlEt2Cl, and AlEt3 as cocatalyst for oligermerization of ethylene with rae-Et（Ind）2ZrC12 has also been investigated. The resluts reveal that under the optimal reaction conditions the catalytic activities of three systems are in the order of rac-Et（ Ind）2ZrCl2 〉 CpZrGl3 〉 （CH3）2SiCp2ZrCl2, while the selectivity of a-olefins of three systems is in the following order： CpZrG13 〉 rac-Et（ Ind）2ZrC12 〉 （CH3）2SiCp2ZrC12. The reaction parameters have an apparent effect on both catalytic activity and selectivity of a-olefins. In addition, rac- Et（Ind）2ZrGlz/AIEtzC1 has better selectivity than rac-Et（Ind）zZrClz/Al（i-Bu）3 and rac-Et（Ind）zZrClz/A1Et3. The results show that the reaction pressure has the important influence on the activity and the distribution of the oligomers. Higher oligomerization temperature and higher ratio of Al/Zr have benefits for the selectivity of a-olefins performance of oligomerization.
参考文献
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