UV/vis in diffusion reflection mode (DRS) and DRIFT spectroscopy have been used to study the surface zirconocene species formed at the interaction of Me2Si(Ind)2ZrCl2 and Me2Si(Ind)2ZrMe2 complexes with the MAO/SiO2 support. Effect of additional activation of these catalysts with TIBA has been studied as well. Structure of type Me2Si(Ind)2ZrMe]+MeMAO]− (C) is formed at the reaction of Me2Si(Ind)2ZrMe2 complex with MAO/SiO2 (a.b. at 456 nm in UV/vis spectra). Interaction of this complex with TIBA results in the formation of new structure (D) with a.b. at 496 nm in UV/vis spectra. The surface species of different composition and structures are formed at interaction of Me2Si(Ind)2ZrCl2 complex with MAO/SiO2. The ratio between these species depends on the zirconium content in the Me2Si(Ind)2ZrCl2/MAO/SiO2 catalysts. According to the DRIFTS data (CO and ethylene adsorption) and ethylene polymerization data these catalysts contain active ZrMe bonds but activity of these catalysts at ethylene polymerization is low. Interaction of Me2Si(Ind)2ZrCl2/MAO/SiO2 with TIBA leads to the formation of the new cationic structure of type (D) with a.b. at 496 nm in UV/vis spectra and great increasing of activity at ethylene polymerization. |