III International Conference

PP-II-103EFFECT OF THE AlEt 3 COCATALYST ON THE INTERNAL DONOR INSUPPORTED ZIEGLER-NATTA CATALYSTSPotapov A.G., Bukatov G.D., Zakharov V.A.Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: potapov@catalysis.ruThe catalyst-cocatalyst interaction was studied for supported Ziegler-Natta catalystscontaining EB (ethyl benzoate) or DBP (di-n-butyl phthalate) as internal donors. As the resultof interaction the catalysts underwent considerable changes of its composition. It was shownby DRIFT spectroscopy, that the weak surface complexes of donors were preferably removedby AlEt 3 from surface of the catalysts. A part of removed donor adsorbs again on thecatalysts surface in the form of complexes with aluminum-containing compounds.The internal donor is an important component in supported Ziegler-Natta catalysts forpropylene polymerization responsible for stereospecificity of these catalysts [1]. When usedin polymerization the catalysts undergo the chemical modifications because of interactionwith the cocatalyst and an external donor [2]. The AlEt 3 cocatalyst interacts with adsorbedTiCl 4 species and removes the internal donor from catalysts surface partially. Earlier we haveshowed the possibility to identify several types of surface EB and DBP complexes insupported Ziegler-Natta catalysts by means of IR-spectroscopy [3]. In the present study weexamine the influence of the AlEt 3 cocatalyst on the chemical composition and on the state ofinternal donors of supported Ziegler-Natta catalyst.Two pairs of the catalysts containing EB or DBP were prepared starting from highlydispersed MgCl 2 support or from Mg(OEt) 2 and treated with the AlEt 3 cocatalyst. It wasfound, the catalysts prepared with use of MgCl 2 support showed similar changes in itschemical composition at the interaction with the cocatalyst. The content of donor and titaniumdecreased upon treatment with cocatalyst and aluminum containing compounds incorporatedinto catalyst composition. The only difference was the more profound decrease of donorcontent for the catalyst with EB as the internal donor. The total content of surface species(donor, titanium and aluminum compounds) markedly increased for both catalysts. It the caseof the catalysts prepared from Mg(OEt) 2 the total content of surface species increased forDBP containing catalyst only and remained the same for the catalysts with EB as the internaldonor.DRIFT study of the catalysts before and after interaction with the cocatalyst showed, thatthe state of donors in the catalysts has markedly changed at the treatment with AlEt 3 . The352