给电子体分子结构对聚乙烯催化剂性能的影响

Effect of molecular structure of electron donor on performance of polyethylene catalyst

将丙二酸酯化合物、邻/对苯二甲酸酯化合物、二醇酯化合物、芳香酸单酯化合物、硝基化合物、氰基化合物、环三藜芦烃(H1)和二苯基蒽类衍生物等给电子体引入Ziegler-Natta(Z-N)聚乙烯催化剂中,研究了上述给电子体对催化剂的聚合活性、氢调敏感性以及聚合粉料堆密度、分子量及其分布的影响。实验结果表明,二酯类化合物可降低催化剂的聚合活性、提高聚合粉料的分子量;芳香酸单酯化合物可提高催化剂的聚合活性和氢调敏感性;硝基和氰基化合物会显著降低催化剂的聚合活性;H1可显著提高催化剂在高氢气乙烯摩尔比(简称氢乙比)条件下的聚合活性和氢调敏感性;二苯基蒽类衍生物可提高催化剂在低氢乙比条件下的聚合活性,但对于催化剂氢调敏感性的影响相对较小。因此,芳香酸单酯化合物和H1类更适于作为Z-N聚乙烯催化剂的给电子体。

The electron donors such as malonate compounds,phthalate/terephthalate compounds,diol ester compounds,aromatic acid monoester compounds,nitro compounds,cyano compounds,cyclotriveratrylene(H1)and diphenylanthracene derivatives were introduced into Ziegler-Natta(Z-N)polyethylene catalysts.The effects of the above electron donors on catalyst polymerization activity,hydrogen response,bulk density of polyethylene powder,molecular weight and molecular weight distribution of polyethylene powder were studied.The results show that all the diesters can decrease the polymerization activity of the catalyst and increased the molecular weight of the polymerization powder.Aromatic acid monoester compounds can enhance the polymerization activity of the catalyst and increase the hydrogen response of the catalyst.Nitro and cyano compounds can significantly reduce the polymerization activity of the catalyst.H1 can significantly improve the polymerization activity and hydrogen response of the catalyst under the condition of high mole ratio of hydrogen to ethylene.Although diphenylanthracene derivatives can improve the polymerization activity of the catalyst under the condition of low mole ratio of hydrogen to ethylene,but they have relatively little effect on the hydrogen response of the catalyst.Therefore,aromatic acid monoesters and H1 are more suitable as electron donors of Z-N polyethylene catalyst.