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Characterization of a model Phillips catalyst by mass spectrometry
Pascal Gabriel Di Croce1, Frédéric Aubriet, Rachel Chéty-Gimondo
1Unité de catalyse et de chimie des matériaux divisés, Université catholique de Louvain, Croix du Sud 2/17, B-1348 Louvain-la-Neuve, Belgium. dicroce@cata.ucl.ac.be
Rapid Communications in Mass Spectrometry : RCM
|March 31, 2004
Summary
A model Phillips catalyst was activated and found to be effective for ethylene polymerization, producing crystalline polyethylene. Surface analysis revealed dome-like structures composed of aligned polymer lamellae after activation.
Area of Science:
- Catalysis
- Polymer Chemistry
- Materials Science
Background:
- The Phillips catalyst is crucial for ethylene polymerization.
- Understanding catalyst activation is key to optimizing polymerization processes.
- Surface characterization techniques provide insights into catalyst behavior.
Purpose of the Study:
- To investigate the oxidative activation of a model Phillips catalyst.
- To analyze the surface species formed during activation.
- To characterize the resulting polyethylene polymer and its morphology.
Main Methods:
- Preparation of a model Phillips catalyst using spin coating of a Cr(III)(Cr(acac)3) precursor on a silicon wafer.
- Oxidative activation of the catalyst at elevated temperatures.
- Surface analysis using Laser Ablation Fourier Transform Mass Spectrometry (LA-FTMS), Fourier Transform Infrared Spectroscopy (FTIR), Laser Desorption/Ionization Mass Spectrometry (LD-IMS), and Atomic Force Microscopy (AFM).
Main Results:
- Chromium precursor degradation and formation of chromium oxide species were observed during activation at 350°C.
- Chromium concentration decreased with increasing temperature.
- The activated catalyst successfully polymerized ethylene into crystalline polyethylene, forming dome-like structures with aligned lamellae observed via AFM.
Conclusions:
- The study successfully characterized the activation process of a model Phillips catalyst.
- The activated catalyst demonstrates efficacy in ethylene polymerization, yielding crystalline polyethylene.
- Morphological analysis revealed unique polymer structures formed on the catalyst surface.