| abstract |
A process for terminating or retarding the rate of polymerization of propylene or a mixture comprising propylene and one or more other olefin monomers, in a gas phase reactor, in the presence of a catalyst system comprising (i) a solid catalyst precursor composition which includes magnesium, titanium, halogen, and carboxylic acid ester; (ii) hydrocarbyl aluminum cocatalyst; and (iii) a silicon compound containing at least one silicon-oxygen-carbon linkage, which comprises introducing a phthalate compound at a rate and in a sufficient quantity to substantially retard or terminate the said polymerization reaction. |