The Role of Two Different Internal Donors (Phthalate and 1,3-Diether) on the Formation of Surface Structure in MgCl2-Supported Ziegler-Natta Catalysts and Their Catalytic Performance of Propylene Polymerization
The role of two different internal donors [a phthalate (diisobutylphthalate) and a 1,3-diether (2,2-diisobutyl-1,3-dimethoxypropane)] on the formation of surface structure in MgCl2-supported Ziegler-Natta catalysts and their catalytic performance of propylene polymerization was investigated by comparing and correlating the catalyst structures and the polymerization characteristics. In the catalyst formation, the 1,3-diether had better affinity for the MgCl2 surface than the phthalate and the 1,3-diether generated the (110) surface more than the (104) surface while the phthalate generated both the (110) and (104) surfaces of MgCl2. With both donors introduced, the (110) and (104) surfaces were generated simultaneously, although the (110) surface was dominant due to the higher affinity via the 1,3-diether. In addition, it seemed probable that the active sites formed on the (110) plane showed isospecific characteristics in the presence of a donor while those formed on the (104) plane could be isospecific regardless of a donor.