Copolymerization of Ethylene/1-Olefin with Mesoporous Titania-Supported Zirconocene/MAO Catalyst

Different mesoporous titanias synthesized by hydrolysis and polycondensation reactions of tetrabutyl titanate with various hydrolysis ratios (H2O/Ti by mole) were employed as supports for zirconocene/MAO catalysts in ethylene/1-olefin copolymerization. The pure anatase phase of titania was detected by X-ray diffraction (XRD) and the morphology was seen by scanning electron microscopy (SEM). The titania obtained was then impregnated with methylaluminoxane (MAO). The amounts of [Al] MAO were measured by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The copolymerization of ethylene/1-hexene (EH) and ethylene/1octene (EO) was performed using titania-supported zirconocene/MAO catalysts. Upon polymerization, it was found that the high surface area of titania apparently exhibited high polymerization activity due to large amounts of [Al] MAO present as seen by EDX and XPS. The obtained copolymer was further characterized by C-13 nuclear magnetic resonance (C-13 NMR) and differential scanning calorimetry (DSC). It revealed that based on C-13 NMR, the random copolymer was obtained for both EH and EO systems. However, EH copolymer exhibited higher melting temperature (T-m) than EO copolymer indicating that the EH system had less comonomer incorporation.