高效催化剂中给电子体对乙烯聚合动力学行为的影响

<正> 人们发现在制备高效齐格勒—纳塔催化剂时,加入适量的给电子体化合物,可大大地改善催化剂的丙烯聚合定向能力和提高催化活性。最常用的、效果最佳的给电子体为芳香羧酸酯类化合物。然而,催化剂中存在给电子体对乙烯聚合过程的影响文献报道尚少。本文研究了以反应法制备的氯化镁为载体的钛系齐格勒-纳塔催化剂在有(或无)邻苯二甲酸二丁酯(DBP)存在时的组成、结构及其用于乙烯聚合动力学行为的差别。不加

EFFECT OF THE DONOR IN THE HIGHLY ACTIVE CATALYST ON THE KINETIC BEHAVIOR OF ETHYLENE POLYMERIZATION

Two catalysts were prepared using reaction method with or without dibuthylphalate(DBP). The surface area, X-ray diffractions and kinetic behavior for ethylene polymerization of these catalysts have been compared. It was found that when the catalyst without DBP(WY-1 system), the kinetic curves for ethylene polymerization show decaying type; however, when the catalyst with DBP(WY-2 system), the kinetic curves are accelerating type. The specific number of active centers C*] are almost same in the two systems. The value of kp of WY-2 system was much greater than that of WY-1 system, but the apparent activation energy of WY-2 system was much lower than that of WY-1 system. It leads to that the catalytic activity of the catalyst with DBP increased greatly in comparision with that of the catalyst without DBP.