Polymerization of propylene using MgCl2 (ethoxide type)/TiCl4/diether heterogeneous Ziegler-Natta catalyst

Heterogeneous Ziegler-Natta catalyst Of MgCl2 (ethoxide type)/TiCl4/diether was prepared. 2,2-Diisobutyl-1,3-dimethoxy propane (DiBDMP), diether, was used as internal donor. Slurry polymerization of propylene was carried out using the catalyst in dry heptane while triethylaluminium (TEA) was used as co-catalyst. The co-catalyst effects, such as catalyst molar ratio, polymerization temperature, H-2 pressure, external donor, triisobutylaluminium. (TiBA) and monomer pressure, on the activity of the catalyst and isotacticity index (H) of the polymers obtained were studied. Rate of polymerization versus polymerization time is of a decay type with no acceleration period. There are an optimum AIM molar ratio and temperature to obtain the highest activity of the catalyst. The maximum activity was obtained at 60 degrees C. Increasing the monomer pressure to 1010000 Pa linearly increased the activity of the catalyst. Addition of hydrogen to 151500 Pa pressure increased activity of the catalyst from 2.25 to 5.45 kg polypropylene (PP) (g cat)(-1) h(-1) using 505000 Pa pressure of monomer. The II decreased with increasing Al/Ti ratio, monomer pressure, hydrogen pressure and increased with increasing temperature to 60 degrees C, following with decrease as the temperature increases. Productivity of 11.55 kg (PP) (g cat)(-1) h(-1) was obtained at 1010000 Pa pressure of monomer and temperature of 60 degrees C. Addition of methyl p-toluate (MPT) and dimethoxymethyl cyclohexyl silane (DMMCHS) as external donors decreased the activity of the catalyst sharply, while the II slightly increased. Some studies of the catalyst structure and morphology of the polymer were carried out using FTIR, X-ray fluorescence, scanning electron microscopy and Brunauer-Emmett-Teller techniques. (c) 2005 Society of Chemical Industry.