DRIFTS study of the interaction of the internal donor in TiCl4/di-n-butyl phthalate/MgCl2 catalysts with AlEt3 cocatalyst

The interaction of di-n-butyl phthalate (DBP as the internal donor) with AlEt3 cocatalyst was studied by DRIFT spectroscopy for the DBP/MgCl2 sample and supported TiCl4/DBP/MgCl2 catalysts. For DBP/MgCl2 sample, it was shown that AlEt3 partially removes all types of DBP complexes from the MgCl2 surface and adsorbs on surface sites released by the removal of DBP. In the case of supported catalysts, the cocatalyst predominantly removes more weak DBP complexes. In addition, the cocatalyst completely removes loosely coordinated DBP and surface complexes of phthaloyl chlorides formed at the catalyst preparation. A part of removed DBP can adsorb again on the catalyst surface as complexes with surface alkylaluminum chloride compounds. The external donor alkylalkoxysilane does not markedly influence the removal of DBP complexes from the catalyst surface.

The internal donors form several types of complexes on the MgCl2 support surface in supported Ziegler-Natta catalysts. A part of the internal donors is removed from the catalysts by AlEt3 cocatalyst. IR-spectroscopy of diffuse reflection (DRIFTS) was used to study the interaction of the DBP/MgCl2 support and TiCl4/DBP/MgCl2 catalysts (where DBP—di-n-butyl phthalate) with AlEt3 cocatalyst. DRIFT spectra of DBP adsorbed on the MgCl2 support (before (A) and after (B) interaction with AlEt3) demonstrate effect of AlEt3 on the distribution of DBP complexes on the MgCl2 surface.Figure optionsDownload as PowerPoint slide