Intra‐ and Interparticle Heterogeneities in Solid Activators for Single‐Site Olefin Polymerization Catalysis as Revealed by Micro‐Spectroscopy. Issue 46 (8th June 2018)

• Record Type: Journal Article
• Authors: Velthoen, Marjolein E. Z.; Meeldijk, Johannes D.; Meirer, Florian; Weckhuysen, Bert M.
• Is Part Of: Chemistry. Volume 24:Issue 46(2018)
• Page Start: 11944
• Page End: 11953
• Publication Date: 2018-06-08
• Subjects: acidity -- heterogeneity -- methylaluminoxane -- polymerization -- spectroscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201801714
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Methylaluminoxane (MAO) is an activator for single‐site olefin polymerization catalysts. Structural characterization of MAO, and in particular the influence of its heterogenization on a silica support, is pivotal for the understanding and optimization of this versatile co‐catalyst. In this work, we demonstrate that by varying the MAO loading on a silica support, we can tune the single particle characteristics in terms of MAO distribution and consequent activity. At low MAO loading we reveal two possible intraparticle MAO distributions: a homogeneous and an Al‐shell type distribution. With increasing MAO loading, the interparticle MAO distribution becomes more homogeneous. Acidity probing measurements on the single particle level explain how a different intraparticle MAO distribution results in a different activity in metallocene activation. Al‐shell particles contain remaining silanol groups and a negligible amount of acid sites and are, therefore, considered inactive for metallocene activation. Only the solid activator particles with a homogeneous intraparticle MAO distribution contain a sufficient number of acid sites, capable of activating the deposited metallocenes. Abstract : Carry that load : A correlation was made between the MAO loading, its distribution on the intraparticle and interparticle level, and the consequent activity in metallocene activation for solid MAO/SiO2 activators in single‐site olefin polymerization catalysts. Only particles with a homogeneous MAO distribution are able to activate metallocenes.