Ethylene polymerization using metallocene catalyst supported on hybrid indenyl silica produced by sol–gel process Original Research Article

In this work, hybrid silica that contained an indenylpropyl organic moiety was synthesized using the sol–gel method from indenylpropylsilane and tetraethylorthosilicate (TEOS). These functionalized silica samples were used in the synthesis of supported metallocene catalysts that were active in the production of linear polyethylene. The reaction conditions, such as the catalyst type and reaction time, for the preparation of indenyl-functionalized silane influenced the incorporation of the organic precursor and the xerogel morphology. Hybrid materials that contained the indenidepropyl ligand were obtained at reaction times between 2 and 6 h with the use of HF or NH3 as catalysts, which resulted in materials with different porosities, surface areas and morphologies. The indenyl-functionalized silica samples with organic contents greater than 10 wt% were thermally stable up to 350 °C. 13C CP-MAS-NMR showed the presence of propyl and indenyl moieties in the hybrid materials. These organic precursors were reacted with ZrCl4·2THF, which led to the formation of supported metallocene catalysts that, when tested in ethylene polymerization reactions, exhibited a dependence on the reaction temperature and the Al/Zr ratio.