丙烯聚合高效负载型Ziegler-Natte催化剂 Ⅱ.Al/Ti比和聚合温度的影响

Highly Active ZieglerNatta Catalyst for Propylene Polymerization ⅡThe Effects of Al/Ti Ratio and Polymerization Temperature

考察助催化剂浓度（Ａｌ／Ｔｉ摩尔比）和聚合温度对ＭｇＣｌ２／ＴｉＣｌ４／ＤＮＢＰ－ＡｌＥｔ３／ＤＰＤＭＳ催化体系聚合行为的影响。发现Ａｌ／Ｔｉ摩尔比对含给电子化合物和不含给电子化合物的催化体系有不同的影响。Ａｌ／Ｔｉ摩尔比增大使含给电子化合物的催化剂活性升高，但产物的全同指数下降；使不含给电子化合物的催化剂活性降低，但全同指数提高。Ａｌ／Ｔｉ摩尔比对聚合活性的影响符合Ｌａｎｇ－ｍｕｉｒ－Ｈｉｎｓｈｅｌｗｏｏｄ竞争吸附模型。当聚合温度为５０℃时，催化剂活性最高，但聚合温度对聚合物全同指数的影响较小；在３０～５０℃之间，聚合符合Ａｒｈｅｎｉｕｓ方程；当聚合温度超过５０℃时，由于聚合物粒子形态发生变化，结果偏离Ａｒｈｅｎｉｕｓ方程。

n this paper,the effects of cocatalyst concentration (Al/Ti ratio) and polymerization temperature on propylene polymerization with MgCl2/TiCl4/DNBPAlEt3/DPDMS as catalysts were investigatedIt is found that Al/Ti ratio has different effect on the polymerization behavior of MgCl2/TiCl4/DNBPAlEt3/DPDMS and MgCl2/TiCl4AlEt3 catalystsWith increase in Al/Ti ratio,the activity of the former catalyst decreased,and the isotactic index of the obtained polymer increased;whereas the activity of the latter catalyst decreased and the isotactic index of the polymer increasedThe effect of cocatalyst concentration on polymerization was in accordance with LangmuirHinshelwood modelPolymerization temperature had no influence on isotactic index of polymer but catalytic activity showed a maximum at 50℃From 30℃ to 50℃,polymerization obeyed Arrhenius equation,but deviation occurred beyond 50℃