Ziegler-Natta Catalyst Preparation Process: Influential Parameters on Particles Morphology and Activity of Catalyst in Propylene Polymerization

Different parameters including temperature and amount of titanium tetrachloride (TiCl4) were examined with respect to Ziegler-Natta catalyst morphology and the catalyst performance during its preparation process. The results show that optimum catalyst activity and morphology are achieved when the process is carried out in two stages. In the first stage of the process، the spherical morphology of the catalyst particles of their support (magnesium chloride/ethanol adduct) with TiCl4 were maintained by gradual increases in reaction temperature from subzero (-5ºC) to high temperature (90ºC)، while the sudden increase of temperature resulted in fragmentation of catalyst particles to non-spherical and very small size species. The effect of the highest temperature limit of this step showed that as the temperature went beyond 90ºC the activity of the catalyst decreased. The second step of the reaction showed that by injection of TiCl4 at high temperature (80-90ºC) the catalyst activities were at the highest point. Study on the final washing of the catalyst showed that at high temperature of washing the catalyst performed its best activity. It can be said that at high temperatures، the probable poisonous adducts which originated from the reaction with TiCl4 could be washed effectively. Finally، according to the obtained results، the optimal operation conditions in catalyst preparation process were proposed those which resulted in high activity and spherical morphology.