Unusual ethylene polymerization results with metallocene catalysts supported on silica

Goretzki, Ralf; Fink, Gerhard; Tesche, B.; Steinmetz, Bernd; Rieger, R.; Uzick, Wolfram

doi:10.1002/(sici)1099-0518(19990301)37:5<677::aid-pola18>3.0.co;2-6

Cited by 36 publications

(32 citation statements)

References 22 publications

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“…Confirming previous observations for the slurry polymerization process [1][2][3][4][5][6][7] we have shown in this paper that even in bulk polymerization, the shell-by-shell like degradation of silica as catalyst support material is observable, but is proceeding much faster than in case of slurry polymerization. Moreover, SEM micrographs of sectioned particles (Figure 7) reveal a broad variance in the degree of fragmentation between single grains.…”

Section: Resultssupporting

confidence: 92%

“…[1][2][3][4][5][6][7] This model was developed with slurry polymerization experiments Full Paper: For the initial steps of propylene bulk phase polymerization with a silica-supported metallocene/MAOcatalyst the processes of polymer growth, particle expansion and carrier fragmentation are investigated. Gravimetric analysis of the kinetics is given.…”

Section: Introductionmentioning

confidence: 99%

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Early Stages of Propylene Bulk Phase Polymerization with Supported Metallocene Catalysts

Knoke

Korber

Fink

et al. 2003

Macro Chemistry & Physics

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For the initial steps of propylene bulk phase polymerization with a silica‐supported metallocene/MAO‐catalyst the processes of polymer growth, particle expansion and carrier fragmentation are investigated. Gravimetric analysis of the kinetics is given. Light optical examination of the particles shows a significant particle expansion during the first minutes of polymerization, which is not comparable to known observation from the slurry process. Electron microscopic investigation on cross sections of the polymer particles allows a detailed insight into the process of polymer growth, carrier fragmentation and particle expansion. The results are compared with the polymer growth and particle expansion model developed with slurry polymerizations under mild model conditions. In bulk phase polymerization particle expansion and carrier fragmentation are much faster due to more drastic reaction conditions. Nevertheless, it is still possible to observe a shell‐by‐shell degradation of the carrier material. Varying start up behaviors of single catalyst grains are observed. We are able to correlate the initial polymerization activity of individual grains with the cocatalyst loading and distribution on the catalyst carrier by means of microanalytical techniques. The results explain the varying start up behaviors of single grains. It becomes clear why different states of fragmentation are mixed up in the observed polymer samples.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Early Stages of Propylene Bulk Phase Polymerization with Supported Metallocene Catalysts

Knoke

Korber

Fink

et al. 2003

Macro Chemistry & Physics

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“…Fink and coworkers showed an unusual ethylene polymerization using metallocene/ SMAO systems, which had triisobutylaluminium present in solution. [37,38] Although the system was heterogeneous, they reported that the produced polyethylene had no definite morphology. Through elemental analysis, using electron diffraction X-ray spectroscopy in microtomed sections of SMAO and supported polyethylene, they concluded that the polymerization occurred only on the external surface of the support and not in its interior.…”

Section: Meso-scale Polymerization Mechanismmentioning

confidence: 99%

Polyethylene Made with In Situ Supported Ni-Diimine/SMAO: Replication Phenomenon and Effect of Polymerization Conditions on Polymer Microstructure and Morphology

Simon

Patel

Soares³

et al. 2001

Macromol. Chem. Phys.

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The catalyst prepared by supporting in situ 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediiminenickel(II) dichloride (1) on silica–methylaluminoxane (SMAO) has high activity for ethylene polymerization, although it is less active than the unsupported system 1/MAO. No external alkylaluminum cocatalyst needs to be added to the in situ supported system. Short chain branches are produced without addition of α‐olefin comonomer, due to the chain‐walking mechanism. Ethylene pressure and polymerization temperature affect the degree of short chain branch formation. At constant ethylene pressure, when the polymerization temperature rises, the short chain branch content also increases. For a given ethylene pressure, there is a threshold polymerization temperature above which polymer particle agglomeration starts to occur. For the conditions investigated herein, from 30 to 50°C the morphology of the polymer particles replicates that of the support. At 55°C, polyethylene starts to become soluble in the reaction medium, and therefore morphological control is gradually lost. Above 70°C, only soluble polymer is produced. Similar results are observed by keeping the temperature constant and changing the ethylene pressure.

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“…The mechanism of the growing polymer particle from the starting of the catalyst particle was investigated by Reichert28 and Fink29 for diolefin and olefin polymerization. It shows that there are different steps in the overall kinetic of the polymerization.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Olefin Polymerization Processes with Metallocene Catalysts

Kaminsky

Müller

Sperber

2005

Macro Materials & Eng

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Summary: Solution and gas phase processes of the polymerization of ethene are compared using new types of pentalenyl bridged ansa‐metallocenes such as [Me3Pen(Flu)]ZrCl2. As of the bridge, the catalyst system is remarkable thermostable up to 105 °C and a deactivation of the metallocene on the silica support can be suppressed. Compared to the non‐supported catalyst in a solution process, the application of the heterogenized system in a gas phase process leads to a decrease in activities while molar masses of the polyethenes are similar. Due to a higher degree of short chain branches of 20–30 per 1 000 carbon atoms instead of 10–17, the melting temperatures are 10 °C lower than those for polymers obtained in the solution process.Basic structure of the here used pentalenyl bridged ansa‐metallocenes.magnified imageBasic structure of the here used pentalenyl bridged ansa‐metallocenes.

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Unusual ethylene polymerization results with metallocene catalysts supported on silica

Cited by 36 publications

References 22 publications

Early Stages of Propylene Bulk Phase Polymerization with Supported Metallocene Catalysts

Early Stages of Propylene Bulk Phase Polymerization with Supported Metallocene Catalysts

Polyethylene Made with In Situ Supported Ni-Diimine/SMAO: Replication Phenomenon and Effect of Polymerization Conditions on Polymer Microstructure and Morphology

Comparison of Olefin Polymerization Processes with Metallocene Catalysts

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