PROPYLENE POLYMERIZATION ON A TITANIUM-MAGNESIUM CATALYST IN THE PRESENCE OF KCL

It is found that polypropylene yields can be increased by a factor of two to three by introducing KCl into the catalytic system l4/MgCl2/eth ylbenzoate-AlR3/p-methoxyethylbenzoate (R = iso-Bu, Et) during propyle ne polymerization. In this case, the fractional composition of polypro pylene, its molecular weight, and characteristics of stereoregularity of the isotatic fraction are not changed. The activation effect of KCl is explained by its ability to form complexes with AlR2Cl, which are produced in the system via catalyst alkylation. AlR2Cl is not a cocata lyst. The time dependence of the rate of propylene polymerization is s atisfactorily described by a second-order formal kinetic equation. The activation of the system is presumed to be assoicated with the stabil ization of active sites, i.e., with a decrease in the deactivation rat e constant, rather than with an increase in the propagation rate const ant and in the number of active sites.