Role of Titanium in Ti/SiO2‐Supported Metallocene‐based Olefin Polymerization Catalysts. Part 2: Particle Fragmentation

Abstract

AbstractA commercial SiO2 modified by the addition of a TiO2 layer on its surface and pore walls offers a support for metallocene‐based ethylene polymerization catalysts with a 35 % improved catalytic activity. The effect of such support modification on the catalyst particle fragmentation during polymerization reactions were assessed. This was performed by exposing the internal cross‐section of several SiO2 and Ti/SiO2‐based metallocene catalyst particles, polymerized at a wide range of reaction conditions, with a Focused‐Ion Beam Scanning Electron Microscope (FIB‐SEM), followed by a semi‐quantitative analysis of polymer, catalyst and macropores of each 2D image obtained. The titanation of the SiO2 lead to a support framework that fractures earlier and more efficiently. This was evidenced by the presence of several empty (polymer‐free) cracks along the support dense‐shell, found more extensively in the Ti‐modified polymerized catalyst particle, which also resulted in a more sustained polymerized particles macroporosity during the course of the reaction.