Ethylene Polymerization catalyzed over Single Site Ni Complex Catalysts supported on Silica

Abstract

The characterization of ethylene polymn. behaviors catalyzed over supported-Ni catalysts activated by MAO was reported. Supported-Ni catalysts were prepd. by treating silica with MAO or TIBAL, followed by reacting pretreated silica with [(2,6-di-iPrPh)2DABAn]NiBr2(1), [(2-py-CH=N-2,6-di-iPrPh)NiBr2](2) and [(2-py-C(CH3)=N-2,6-di-iPrPh)NiBr2](3). In ethylene polymn. with Silica/MAO/(1), Silica/TIBAL/(1), a max. activity was obtained at 30 DegC in all cases. The max. activity is about 1/4 of that of corresponding unsupported catalyst. As polymn. temp. increased, the no. and kinds of branching increased, whereas the mol. wt. of prepd. polymers decreased because of enhanced beta -hydride elimination and reinsertion process. In ethylene polymn. with Silica/MAO/(2) and Silica/MAO/(3), powders were produced between 0 DegC and 50 DegC. The catalytic activity of Silica/MAO/(2) was higher than that of Silica/MAO/(3) in ethylene polymn.