Catalysis of Ethylene to Linear Low-Density Polyethylene with Iron-Based Diimine Complex Immobilized on Calcosilicate and Silica-Supported rac-Et(Ind)2ZrCl2

摘要

Iron-based diimine complex was immobilized on calcosilicate (CAS-1) to form heterogeneous precatalyst, which oligomerized ethylene to a-olefins even without the use of aluminum alkyl compounds as activators. The a-olefins, upon the catalysis of another catalyst, i.e., silica-supported rac-Et(Ind)2ZrCl2, copolymerized with ethylene to produce linear low-density polyethylene (LLDPE). The copolymerization reactions could be performed with the addition of triethylaluminum alone because of the introduction of methylaluminoxane to CAS- 1 and silica during the supporting process. In addition to the formation of more a-olefins with lower molar mass, the layered structure of CAS-1 acted well in the controlled release of a-olefins in the copolymerization process. The simultaneous employment of the aforementioned two catalysts hence resulted in high catalytic activities, smooth kinetic process, well-regulated branching degree, higher molecular weights (Mn), improved thermal stability, and better morphology of the LLDPE obtained.