Abstract

The effect of the alcohol nature in TiCl4 catalysts supported on MgCl2, modified by the recrystallization technique with SiCl4, has been investigated in terms of activity and tacticity control. A series of alcoholic solutions of MgCl2, using 1-hexanol, t-butanol, butanol, iso-propanol, propanol and ethanol, were recrystallized with SiCl4 and the supports were subsequently impregnated with TiCl4. Also, as a way of comparison, catalysts were prepared from solutions of MgCl2 in 1-hexanol recrystallized by solvent evaporation and quick cooling. The supports and catalysts were characterized by infrared and energy dispersive scanning (EDS). Polymerization of ethylene and propylene was performed under different temperature and pressure conditions, using triethylaluminium as a cocatalyst in the absence of electron donors. The catalytic activity depended strongly on the length of the alkyl group and the nature of the isomeric alcohol used in the treatment of the support. The yield and isotacticity of the polypropylene are governed by polymerization parameters such as pressure and support treatment. The EDS results confirmed the presence of alkoxysilanes in the catalysts treated with SiCl4.