XPS study of Al‐Alkyl effect on Ziegler–Natta catalytic system

Abstract

X-ray photoelectron spectroscopy was performed on Ziegler-Natta catalysts to elucidate the effect of aluminum alkyl compounds (Al-Alkyl) on TiCl x /MgCl 2 /THF catalytic system. Chemical structure and element composition changes of catalysts were studied and various reduction activity of Al-alkyl on catalysts was identified in different processes. The analytical results indicate that XPS is an acceptable method to measure titanium valence in Al-alkyl-ZN catalysts with a proper sample protection method. The XPS results demonstrate that the Al-alkyl treatment of ZN catalysts could influence the chemical state of titanium dramatically. In Method A, the valence of Ti was reduced to Ti 3+ partially, and the contents of Ti 3+ increased with the increasing amount of DC, but Ti 2+ was absent. With same amount of Al%, combination of DC and THA has better reduction effect than DC with Method B.