Copolymerization of ethylene/1-olefin over titania-supported metallocene catalyst

Abstract

Because of the commercial interest of using metallocene catalysts for olefin polymerization, it has led to an extensive effort for utilizing metallocene catalysts more efficiently. It is known that linear low-density polyethylene (LLDPE) can be synthesized by copolymerization of ethylene and 1-olefins using metallocene catalysts. However, it was found that homogenization of metallocene has two major disadvantages; the lack of morphology control of polymers produced and reactor fouling. Therefore, heterogenization of metallocene was brought to solve these problems. This present study reveals the effect of TiO2 as a support for zirconocene/dMMAO catalyst on in situ copolymerization of ethylene/1-hexene in order to produce the linear low-density polyethylene (LLDPE). First, the dMMAO was impregnated onto various phases of TiO₂ supports, and then characterized by XPS, SEM/EDX and ICP/AES. It was found that the [Al]dMMAO is located mostly on the outer or external surface of TiO2 supports. The [Al]dMMAO distribution on the TiO2 supports is good as seen by SEM/EDX. The copolymer obtained was further characterized by DSC, SEM/EDX and ¹³C NMR. The highest activity occurred when the anatase phase of TiO2 was employed due to the optimal interaction between the support and cocatalyst as seen by TGA. The copolymer obtained were random copolymer having different triad distribution as proven by ¹³C NMR.