Study On Organic/Inorganic Support Ziegler-Natta Catalyst For Ethylene Gas Polymerization

In this paper, the gas phase polyethylene catalyst with polymer microspheres and MgCl₂ as the catalyst carrier was prepared and characterized. The polymerization behavior of Ziegler-Natta with organic-inorganic complex carrier was compared with the catalyst immobilization on silica gel and MgCl₂ through the ethylene polymerization.The monodisperse crosslinked polystyrene microspheres were prepared by suspension polymerization and the factors such as monomer loading, initiator loading, crosslinking agent loading, dispersing agent loading and stirring speed, having effect on particle size of microspheres, were investigated systematically. The best conditions for suspension polymerization of styrene are as follows: the loading of styrene was 20% of water phase, the loading of divinylbenzene was 4% (wt%) of styrene, the loading of BPO was 1% (wt%) of styrene, the reaction temperature was 60℃, the stirring speed was 500rpm and the reaction time was 24 hours. The microspheres morphology, particle size and dispersion were characterized by the optical microscopy and scanning electron microscopy, and it was shown that the crosslinked polystyrene microspheres obtained have good shape and porous surface as well as good dispersion.In addition, a kind of gas polyethylene catalyst supported on organic-inorganic composite support was prepared by the dissolved-sedimentation method. First, the elemental analysis of the resulting catalyst was did and determined the content of Ti, Mg and Cl, and then the catalyst and the carrier were characterized; Finally, the catalysts were evaluated and compared through ethylene polymerization and the factors having influence on the catalyst were investigated such as the Al-Ti molar ratio, temperature, pressure, etc.. The results showed that the particle sharp of polyethylene catalyzed by the gas phase polyethylene catalyst supported on organic-inorganic composite carrier was well0.312, and the bulk density of production was large as well as little content of fine powder and inorganic ash, but the catalytic activity was not as well as the catalyst supported on silica gel and MgCl₂.