Catalysis
Ting Fu; Ruihua Cheng; Xuelian He; Zhen Liu; Zhou Tian; Boping Liu
Abstract
Vanadium-modified (SiO2/MgO/MgCl2)•TiClx Ziegler-Natta catalysts were prepared through co-impregnation of water-soluble magnesium and vanadium salts under different pH values. Several key factors such as pH value of co-impregnation solution during catalyst preparation, catalyst performances including ...
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Vanadium-modified (SiO2/MgO/MgCl2)•TiClx Ziegler-Natta catalysts were prepared through co-impregnation of water-soluble magnesium and vanadium salts under different pH values. Several key factors such as pH value of co-impregnation solution during catalyst preparation, catalyst performances including catalytic activity, ethylene/1-hexene copolymerization and hydrogen response were investigated. It is found that the components, structures and performance of the catalysts are obviously affected by changing the pH value (pH=5, 7 and 9) of co-impregnation solution. An appropriate pH value (pH=7) can maximize catalytic activity and hydrogen response, while lower pH value (pH=5) is beneficial to the 1-hexene incorporation. The GPC results show that the polymers obtained have high average molecular weight.
Catalysis
Ting Fu; Ruihua Cheng; Xuelian He; Zhen Liu; Zhou Tian; Boping Liu
Abstract
A novel imido-modified SiO2-supported Ti/Mg Ziegler-Natta catalyst for ethylene and ethylene/1-hexene polymerization is investigated. The catalyst is prepared by modification of (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalysts via supporting vanadium species followed by reaction with p-tolyl isocyanate ...
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A novel imido-modified SiO2-supported Ti/Mg Ziegler-Natta catalyst for ethylene and ethylene/1-hexene polymerization is investigated. The catalyst is prepared by modification of (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalysts via supporting vanadium species followed by reaction with p-tolyl isocyanate as imido agents, to get the merits from both the SiO2-supported imido vanadium catalyst and the (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalyst. The effects of cocatalyst amount, hydrogen and dosage of 1-hexene on polymerization behavior and the microstructures of their polymers are systematically investigated. Compared with (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalysts and vanadium-modified (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalysts, the imido-modified SiO2-supported Ti/Mg catalysts show lower but more stable activity including homopolymerization, polymerization with hydrogen and copolymerization owing to imido ligands, indicating that p-Tolyl isocyanate was unfavorable to improving catalytic activity but benefited the stability, and the products of all catalysts show lower 1-hexene incorporation but much higher molecular weight (MW) with medium molecular weight distribution (MWD). The most unique feature of the novel catalysts is the excellent hydrogen response without lowering the polymerization activity, showing great potential for industrial application.
