Abstract: A process for the production of elastomeric polypropylene is disclosed. The process entails contacting the propylene monomer neat or in an unreactive hydrocarbon solvent, with a catalyst in a recirculated, stirred reactor at a temperature of about 60.degree. to 80.degree. C. thereby producing elastomeric polypropylene. The reactor contents are in the slurry/solution phase and are essentially free of catalyst poisons. The reactor is capable of recirculating contents that are very viscous such that the reactor contents are well mixed while a portion of the contents of the reactor containing propylene, any solvent, and elastomeric polypropylene are continually removed by the use of a high viscosity pump to recover the elastomeric polypropylene.

Abstract: A process control scheme for temporarily slowing or killing the production of polypropylene while idling the reactor using a fourth generation catalyst system containing a solid magnesium chloride supported titanium tetrachloride catalyst component containing an internal strong electron donor in combination with a silicon compound, and an organoaluminum compound (cocatalyst) is disclosed. This process entails the introduction of an amount of an external strong electron donor to the ongoing polymerization reaction. The polymerization reaction can be restarted by introducing an additional amount of the organoaluminum compound.