Synthesis of (Ind)2ZrCl2 Catalyst for Copolymerization of Ethylene and Propylene: Parameters Effect on Productivity

Bis(indenyl)zirconium dichloride as a catalyst was synthesized using a modified method at the room temperature. Polymerization of ethylene and copolymerization of ethylene and propylene were carried out by this metallocene catalyst. Ethylene propylene (P/E) feed ratios of 0.25, 0.5, 1, and 2 were employed into the copolymerization systems. Copolymerization conditions like cocatalyst/catalyst ratio, copolymerization temperature, feed ratio and the viscosity average molecular weight (Mv) changing with copolymerization temperature were investigated. Higher ratio of [Al]/[Zr]=750:1 increased the activity of the catalyst. However, higher concentration of the cocatalyst slightly reduced the activity. Viscosity-average molecular weight of polymer decreased with high ratio of [Al]/[Zr]. The highest activity was obtained at 60oC. Increases in copolymerization temperature decreased the viscosity-average molecular weight and ethylene content of the polymeric products. Increases in propylene content of the feed ratio producedamorphous polymers with products of increased glass transition temperatures.Kinetic reaction displayed a decay type of reaction

1-Hexene Polymerization Using Ziegler-Natta Catalytic System with Response Surface Methodology

The effects of process conditions and their interactions on the catalyst activity in 1-hexene polymerization were studied with design of experiments by response surface methodology (RSM) using a commercial Ziegler-Natta (ZN) catalyst in the form of TiCl4/MgCl2/Di-n-butyl phthalate. The effect of different operational variables on the catalyst activity was examined by performing the primary experiments of 1-hexene polymerization.  Among different operational variables, three variables including monomer concentration, polymerization temperature and cocatalyst/catalyst molar ratio (Al/Ti) were considered as the main parameters which affected the catalyst activity in the 1-hexene polymerization. The Box-Behnken model with three main parameters in three level responses for each factor was applied to analyze the parameter relationships. After demonstrating the reproducibility of the experimental results, the statistical analysis of experimental data showed that the monomer concentration and Al/Ti molar ratio affected the catalyst activity significantly. It was found that, at room temperature, by increasing the monomer concentration from 80.0 mmol to 239.9 mmol, the activity of the studied ZN catalyst increased from 75.2 to 265.1 gpoly(1-hexene)/gcat. In addition, by changing the Al/Ti ratio from 45.9 to 136.8, the catalyst activity increased from 145.2 to 265.1 gpoly(1-hexene)/gcat. The maximum activity of catalyst was obtained at the polymerization temperature around 25°C, and by increasing the temperature the activity of studied catalyst decreased. Based on the RSM, the best polymerization condition was obtained at a polymerization temperature of about 35°C, Al/Ti ratio of 136.8, and monomer concentration of 239.9 mmol, which resulted in maximum productivity of the catalyst

Synthesis of Metallocene Catalyst for Terpolymerization of Ethylene, Propylene and Diene

The bis(indenyl) zirconium dichloride catalyst was synthesized by a modified method at room temperature. Terpolymerization of ethylene, propylene and diene monomers were carried out using this metallocene catalyst under different conditions of different feed ratios of monomers, co-catalyst/catalyst ratios and polymerization temperatures. Methylaluminoxane (MAO) was used as a co-catalyst. The highest activity of catalyst was obtained at total pressure 4 bar, co-catalyst/catalyst ratio [Al]/[Zr]=600, polymerization temperature 60°C and E/P=67:33 and momomer feed ratio of 1700 kgEPDM/molZrh. The activity of catalyst showed bell-shaped behaviors versus co-catalyst/catalyst ratio ([Al]/[Zr]) and polymerization temperatures. The viscosity-average molecular weight (Mv) of terpolymers increased with increasing total pressure at different feed ratios of monomers. However, the viscosity-average molecular weight of terpolymers decreased at higher co-catalyst/catalyst ratios ([Al]/[Zr]) and higher polymerization temperatures. The increases in propylene and diene monomers in the feed ratios decreased the catalyst activity and viscosity-average molecular weight of terpolymers. The ratio of maximum average rate of terpolymerization to an average rate of terpolymerization at the end of the polymerization (DI) for different terpolymerization conditions was relatively high; an indication of the decay kinetics for this type of metallocene catalyst. Increasing the co-catalyst/catalyst ratio up to [Al]/[Zr] = 500 increased the Et% and ENB% in the final obtained polymers. However, increasing the polymerization temperature, diene and propylene concentrations in the feed ratio decreased the Et% and increased the ENB% contents in the final obtained polymers. Tg of the final terpolymers was between -64 and -52°C. The study on microstructures of some polymer revealed block type of chain microstructures