Polymerization of olefins by ziegler catalyst. I. Polymerization of propylene by AlEt3TiCl4 catalyst

The polymerization of propylene with AlEt3TiCl4 catalyst was studied in detail. The molecular weight of polymers decreases with the temperature in the range 2–40°C., and increases proportionally to the pressure, but it does not depend on the AlEt3/TiCl4 ratio. The rate is proportional to the amount of catalyst as well as to the propylene pressure. The optimum mole ratio of AlEt3 to TiCl4 is 4. In regard to the temperature, the rate is maximum at 40°C. The apparent activation energy is about 5.7 kcal./mole for the range 2–40°C. The activity of the catalyst decreases with the length of time it is kept at 40–60°C. after its formation, but at 30°C. the activity is retained almost completely for 4 hr. The polymerization rate is observed to decrease as the reaction proceeds, even at constant pressure. It is unreasonable to attribute this fact solely to the deactivation of catalyst observed at above 40°C., because such a decrease in rate occurs even at 30°C.