Preparation and characterization of agglomerated porous hollow silica supports for olefin polymerization catalyst

Self-prepared porous hollow silica (PHS) nanoparticles were agglomerated with an oil (kerosene)-ammonia method and used as a novel support of metallocene catalysts for olefin polymerization. Transmission electron microscopy (TEM), scanning electron microcopy (SEM), small-angle X-ray diffraction (SA-XRD) and nitrogen adsorption-desorption were employed to characterize the morphologies and mesostructures of the PHS particles and agglomerated PHS particles. It was found that the agglomerated PHS particles had an average diameter between 15 and 30 mu m, a specific surface area of 214 m(2)/g, a pore diameter of 11-18 nm and a pore volume of 1.41 mL/g. Metallocene catalysts prepared with the agglomerated PHS as support demonstrated a very high activity of 8350 g PE/gCata. for ethylene polymerization due to their particular morphology and mesostructures. Analysis with Differential Scanning Calorimetry (DSC), SEM, TEM and molecular weight analysis indicated that the polyethylene product was composed of tiny spherical particles with good crystalline and narrow molecular weight distribution, and the morphology and structure of the individual PHS support particle remained unchanged in polyethylene following the polymerization. (C) 2007 Published by Elsevier B.V.