Effect of experimental conditions on ethylene polymerization within-situ-supported metallocene catalyst

Chu, Kyung-Jun; Soares, João B. P.; Penlidis, Alexander

doi:10.1002/(sici)1099-0518(20000515)38:10<1803::aid-pola650>3.0.co;2-x

Cited by 34 publications

(30 citation statements)

References 18 publications

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“…This inverse relationship between catalyst activity and Zr loading indicates that only a limited proportion of Zr sites are effectively immobilized and activated from zirconocene catalyst. This fact has been previously observed in ethylene polymerization with homogeneous and supported metallocene catalysts20, 22, 33–36 because as explained above in the UV‐Vis spectra, at higher Zr loadings, it increases the probability to get zirconocene dimmers. These inactive bimetallic species are responsible of the bimolecular deactivation of the metallocene compound 37–40.…”

Section: Resultssupporting

confidence: 70%

Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Carrero

Grieken

Paredes

2010

J of Applied Polymer Sci

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Methylaluminoxane (MAO)/(nBuCp) 2 ZrCl 2 metallocene catalytic system was supported on silica and silica-alumina. The Zr loading was varied between 0.2-0.4 wt %, and the MAO amount was calculated to get (Al MAO / Zr) molar ratios between 100 and 200, suitable for the industrial ethylene polymerization of supported metallocene catalysts. Catalytic activity was statistically analyzed through the response surface method. Within the ranges studied, it was found that Zr loading had a negative effect on polymerization activity, which increases with the (Al MAO /Zr) molar ratio. Catalysts supported on silica-alumina are more active than those supported on silica, needing less MAO to reach similar productivity, which constitutes an important advantage from an economical and environmental point of view. Supported catalysts were characterized by ICP-AES, SEM-energy-dispersive X-ray spectrometer, and UV-Vis spectroscopy, whereas polyethylenes were characterized by GPC and DSC. Molecular weight and crystallinity are not influenced by Zr loading or (Al MAO /Zr) ratio, in the range studied. In general, silica-supported MAO/(nBuCp) 2 ZrCl 2 catalysts give polyethylenes with higher molecular weight and polydispersity but lower crystallinity.

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Section: Resultssupporting

confidence: 70%

Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Carrero

Grieken

Paredes

2010

J of Applied Polymer Sci

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“…The supported metallocene complexes had lower activities than the corresponding homogeneous metallocene catalysts, as expected and already observed using the in situ immobilization procedure 5,6. Among the possible reasons for this poor catalytic activity of the supported systems are the significant steric hindrance around the active site caused by the support surface, the deactivation of catalytic sites and the inefficient production of active sites during the immobilization process,5 generating nearly 1% of total Zr active species after the catalyst immobilization procedure 20…”

Section: Resultssupporting

confidence: 73%

“…No other preparation steps are involved and no pre‐contacting of catalyst, cocatalyst and support is required. This procedure was first described some years ago, and has been used in ethylene homopolymerization and copolymerization with the catalysts Cp 2 ZrCl 2 , Cp 2 HfCl 2 , Et(Ind) 2 ZrCl 2 , Et(Ind) 2 ZrMe 2 , [(C 5 Me 4 )SiMe 2 N( t ‐Bu)]TiCl 2 (CGC catalyst from Dow) and [(CH 2 ) 5 (C 5 H 4 ) 2 ][(C 9 H 7 )ZrCl 2 ] 2 , a bridged binuclear catalyst 1–8…”

Section: Introductionmentioning

confidence: 99%

Ethylene and Propylene Polymerization Using In Situ Supported Me₂Si(Ind)₂ZrCl₂ Catalyst: Experimental and Theoretical Study

Franceschini¹,

Santos

Ferreira

et al. 2006

Macro Materials & Eng

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Summary: Me2Si(Ind)2ZrCl2 was in situ immobilized onto SMAO and used for ethylene and propylene polymerization in the presence of TEA or TIBA as cocatalyst. The catalytic system Me2Si(Ind)2ZrCl2/SMAO exhibited different behavior depending on the amount and nature of the alkylaluminum employed and on the monomer type. The catalyst activity was nearly 0.4 kg polymer · g cat−1 · h−1 with both cocatalysts for propylene polymerization. Similar activities were observed for ethylene polymerization in the presence of TIBA. When ethylene was polymerized using TEA at an Al/Zr molar ratio of 250, the activity was 10 times higher. Polyethylenes made by in situ supported or homogeneous catalyst systems had practically the same melting point (Tm). On the other hand, poly(propylenes) made using in situ supported catalyst systems had a slightly lower Tm than poly(propylenes) made using homogeneous catalyst systems. The nature and amount of the alkylaluminum also influenced the molar mass. The poly(propylene) molar mass was higher when TIBA was the cocatalyst. The opposite behavior was observed for the polyethylenes. Concerning the alkylaluminum concentration, the molar mass of the polymers decreased as the amount of TEA increased. In the presence of TIBA, the polyethylene's molar mass was almost the same, independent of the alkylaluminum concentration, and the poly(propylene) molar mass increased with increasing amounts of cocatalyst. The deconvolution of the GPC curves showed 2 peaks for the homogeneous system and 3 peaks for the heterogeneous in situ supported system. The only exception was observed when TEA was used at an Al/Zr molar ratio of 500, where the best fit was obtained with 2 peaks. Based on the GPC deconvolution results and on the theoretical modeling, a proposal for the active site structure was made.Molar mass distribution deconvolution of polyethylene prepared with the system Me2Si(Ind)2ZrCl2/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.magnified imageMolar mass distribution deconvolution of polyethylene prepared with the system Me2Si(Ind)2ZrCl2/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.

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“…One way to do so is to support them on silica, alumina, magnesium dichloride, or other supports. [10] We have recently shown that the new metallocene catalyst in-situ immobilization technique on MAO-modified silica used to polymerize ethylene [11,12] could also be employed to obtain polypropylene with the catalyst Me 2 Si(Ind) 2 ZrCl 2 . [13,14] In the present investigation, we compare the effect of the type and concentration of alkylaluminum cocatalyst on propylene polymerization using the in-situ immobilization technique with the catalysts Me 2 Si(Ind) 2 ZrCl 2 and Me 2 Si(2-Me-Ind) 2 ZrCl 2 .…”

Section: Introductionmentioning

confidence: 99%

Polypropylene Made with In‐Situ Supported Me₂Si(Ind)₂ZrCl₂ and Me₂Si(2‐Me‐Ind)₂ZrCl₂ Catalysts: Properties Comparison

Franceschini¹,

Santos

Soares

2004

Macro Chemistry & Physics

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Summary: Propylene homopolymerizations were carried out using Me2Si(Ind)2ZrCl2 and Me2Si(2‐Me‐Ind)2ZrCl2, MAO‐modified silica, and common alkylaluminum cocatalysts. Supported catalysts were prepared by the in‐situ immobilization technique. The effect of the type and concentration of alkylaluminum on propylene polymerization was evaluated using TEA (triethylaluminum), IPRA (isoprenylaluminum), and TIBA (triisobutylaluminum) as cocatalysts. The polymers were analyzed by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and scanning electronic microscopy (SEM). The effect of the type and concentration of alkylaluminum on the melting temperature and the molar mass of the polypropylene was the same for both catalysts. The polymers made with in‐situ supported catalyst had lower melting points and, in almost all polymerization conditions, higher molar masses than those produced by homogeneous polymerization. Polypropylene samples made with Me2Si(2‐Me‐Ind)2ZrCl2 had higher melting temperatures and molar masses than those made with Me2Si(Ind)2ZrCl2. SEM micrographs showed that the polymers obtained with in‐situ supported systems had a well‐defined morphology, confirming that the polymerization indeed took place onto the silica support.SEM micrographs of polypropylene particles obtained with Me2Si(2‐Me‐Ind)2ZrCl2 in the presence of IPRA.magnified imageSEM micrographs of polypropylene particles obtained with Me2Si(2‐Me‐Ind)2ZrCl2 in the presence of IPRA.

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Effect of experimental conditions on ethylene polymerization within-situ-supported metallocene catalyst

Cited by 34 publications

References 18 publications

Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Ethylene and Propylene Polymerization Using In Situ Supported Me₂Si(Ind)₂ZrCl₂ Catalyst: Experimental and Theoretical Study

Polypropylene Made with In‐Situ Supported Me₂Si(Ind)₂ZrCl₂ and Me₂Si(2‐Me‐Ind)₂ZrCl₂ Catalysts: Properties Comparison

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Effect of experimental conditions on ethylene polymerization within-situ-supported metallocene catalyst

Cited by 34 publications

References 18 publications

Ethylene polymerization with methylaluminoxane/(nBuCp)2ZrCl2 catalyst supported on silica and silica‐alumina at different AlMAO/Zr molar ratios

Ethylene polymerization with methylaluminoxane/(nBuCp)2ZrCl2 catalyst supported on silica and silica‐alumina at different AlMAO/Zr molar ratios

Ethylene and Propylene Polymerization Using In Situ Supported Me2Si(Ind)2ZrCl2 Catalyst: Experimental and Theoretical Study

Polypropylene Made with In‐Situ Supported Me2Si(Ind)2ZrCl2 and Me2Si(2‐Me‐Ind)2ZrCl2 Catalysts: Properties Comparison

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Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Ethylene polymerization with methylaluminoxane/(nBuCp)₂ZrCl₂ catalyst supported on silica and silica‐alumina at different Al_MAO/Zr molar ratios

Ethylene and Propylene Polymerization Using In Situ Supported Me₂Si(Ind)₂ZrCl₂ Catalyst: Experimental and Theoretical Study

Polypropylene Made with In‐Situ Supported Me₂Si(Ind)₂ZrCl₂ and Me₂Si(2‐Me‐Ind)₂ZrCl₂ Catalysts: Properties Comparison