Effects of Silica Support Properties on the Performance of Immobilized Metallocene Catalysts for Ethylene Polymerization

Abstract

The choice of the silica support for 𝜶-olefin polymerization catalysts has overwhelming ramifications on the overall metal loading, catalyst performance, and properties of the resulting polymer. There are several physical properties of a silica support to consider but the pore volume and pore diameter are the two of the most important support properties in such considerations. During the catalyst immobilization process and the subsequent polymerization reaction, the change in the pore volume can either facilitate or inhibit the mass transfer of catalytic compounds and monomers within and throughout the catalyst particle. This work presents the experimental study on the effects of pore diameter and pore volume in porous silica particles used to support rac-Et(ind) 2 ZrCl 2 catalyst on ethylene polymerization. The amount of immobilized methylaluminoxane (MAO) is varied for three commercially available silica micro-particles with similar surface areas and particle sizes. It has been observed that each type of silica exhibits different effects of the immobilized MAO on their pore characteristics, although a general trend is observed. Ethylene polymerization in slurry phase with the prepared supported catalysts also shows that the polymerization activities can be correlated with pore diameter and surface area for the three silica supports.

Ethylene Polymerization over Metal–Organic Framework-Supported Zirconocene Complexes

“…This support then acts as a template for controlled polymer growth and therefore the properties of the support influence the polymerization process significantly . Physical properties, such as surface area, porosity, particle size, and morphology, determine the polymer growth. − Additionally, the chemical nature of the support material, not only limited to properties, such as hydroxyl content, friability, and acidity, also determines the effectivity of the catalyst material. − Based on all of these previous observations, it can be established that optimizing the support material for making metallocene-based catalyst materials is as a result detrimental to catalytic olefin polymerization.…”