FTIR studies of titanium tetrachloride and magnesium dichloride complexes with aromatic esters relevant to Ziegler-Natta catalysts

摘要

Abstract: Esters of aromatic carboxylic acids and dicarboxylic acids show different effects when used as electron donors in the synthesis of milled MgCl$-2$/- supported Ziegler-Natta catalysts. Such Ziegler-Natta catalysts are synthesized by cogrinding anhydrous MgCl$-2$/ with the ester, then reacting the resulting support with TiCl$-4$/ followed by washing and drying. Alternatively, the catalyst may be synthesized by cogrinding MgCl$-2$/ with a TiCl$-4$/-aromatic ester complex. The catalyst is activated by a trialkyl aluminum in order to polymerize propene or other $alpha@-alkenes. Esters of the monoacids generally enhance the activity of the catalyst (relative to no ester), and the produced polypropene is also more isotactic. Esters of the diacids also enhance the isotacticity of the polymer produced somewhat, but the activity of the catalyst is lower. !4