Imido-modifed SiO2-supported Ti/Mg ziegler-Nattacatalysts for ethylene polymerization and ethylene/1-hexene copolymerization

Anovel imido-modifed SiO polymerization is investigated. The catalyst is prepared by modifcation of (SiO 2-supported Ti/Mg Ziegler-Natta catalyst for ethylene and ethylene/1-hexene 2/MgO/MgCl2)TiClx ZieglerNatta catalysts via supporting vanadium species followed by reaction with p-tolyl isocyanate as imido agents, to getthe merits from both the SiO2-supported imido vanadium catalyst and the (SiO2/MgO/MgCl2)TiClx Ziegler-Nattacatalyst. The effects of cocatalyst amount, hydrogen and dosage of 1-hexene on the polymerization behavior and themicrostructures of their polymers are systematically investigated. Compared with (SiO2/MgO/MgCl2)TiClx ZieglerNatta catalysts and vanadium-modifed (SiO2/MgO/MgCl2)TiClx Ziegler-Natta catalysts, the imido-modifed SiO2-supported Ti/Mg catalysts show lower but more stable activity for homopolymerization, polymerization with hydrogenand copolymerization owing to imido ligands, indicating that p-tolyl isocyanate is unfavorable for improving catalyticactivity but benefcial for the stability, and the products of all catalysts show lower 1-hexene incorporation but muchhigher molecular weight (MW) with medium molecular weight distribution (MWD). The most unique feature ofthe novel catalysts is the excellent hydrogen response without lowering the polymerization activity, showing greatpotential for industrial application. Polyolefns J (2016) 3: 103-117

Keywords:

Ziegler-Natta catalyst , imido V compound , ethylene polymerization , polymerization kinetics , copolymerization