Copolymerization of ethylene/1-olefin with mesoporous titania-supported metallocene catalyst

Abstract

Nowadays metallocene catalysts have been interesting both research and commercial. However general metallocene catalysts have had two major disadvantages of homogeneous system that are the lack of controllable morphology and occur fouling in the reactor. To overcome these problems the supported metallocene catalyst system has been investigated and developed continually. Besides this strategy may be less amount of MAO usage and utilized in gas-phase processes. In this study, metallocene catalyst was used for linear low density polyethylene syntheses by ethylene and 1-olefin copolymerization with various surface area mesoporous titania as support. First, mesoporous titanias were synthesized in various hydrolysis ratios (Ti/H2O), and characterized by BET, XRD, SEM. The obtained titania was found that the mesoporous form of titania was obtained in isotherms type IV by BET technique. Anatase phase was detected by XRD and structure of mesoporous titania was seen by SEM. The various suface area mesoporous titanias were impregnated with methylaluminoxane, and then characterized by SEM/EDX, XPS and TGA. It was found that the [Al]MAO distribution on the TiO2 supports was good as seen by SEM/EDX and XPS. The copolymer obtained was further characterized by 13C NMR. The highest activity occurred when the highest surface area of mesoporous 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.