Ethylene polymerization with catalyst systems based on supported metallocenes with varying steric hindrance

Guimarães, Rafael Eisinger; Stedile, Fernanda Chiarello; Santos, João Henrique Zimnoch dos

doi:10.1016/s1381-1169(03)00411-4

Cited by 43 publications

(38 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The supported catalysts produced polymers with higher M w than those obtained with the corresponding metallocene complexes. As expected, polymers with broader MWD values were obtained with the supported metallocenes, accordingly with the heterogeneous nature of these catalysts [13,44,45].…”

Section: Resultssupporting

confidence: 75%

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Cérdán

Parada

Ibarra

et al. 2007

Designed Monomers and Polymers

View full text Add to dashboard Cite

Abstract-Metallocene complexes Cp 2 TiCl 2 , Cp 2 ZrCl 2 , Cp 2 Zr(N n Bu 2 ) 2 , Cp 2 Ti(η 1 -OC(O)C 6 H 5 ) 2 and Cp 2 Zr(η 1 -OC(O)C 6 H 5 ) 2 were supported on MgCl 2 /SiCl 4−n (n-C 6 H 13 O) n carrier and used for ethylene polymerization. The supported complexes result in highly active catalysts when treated with different aluminum alkyl-based co-catalysts. These catalysts are able of tuning the final properties of the produced polyethylenes. Mixed composites of metallocenes and conventional Ziegler-Natta catalysts supported on the same carrier were also studied. A supported zirconocene Cp 2 Zr(η 1 -OC(O)C 6 H 5 ) 2 on MgCl 2 /SiCl 4−n (n-C 6 H 13 O) n resulted in a highly active catalyst that eject control on the molecular weight, crystallinity and morphology of the resultant polyethylene.

show abstract

Section: Resultssupporting

confidence: 75%

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Cérdán

Parada

Ibarra

et al. 2007

Designed Monomers and Polymers

View full text Add to dashboard Cite

show abstract

“…22,44 In the present case, in spite of the presence of MAO species on silica surface, such hybrid systems produce polymers with even higher M w in comparison to those observed for (iBuCp) 2 ZrCl 2 supported on bare silica. One cannot neglect the possibility that the Ti complexes (due to their steric demanding complexes) might be playing the role of spacers, hindering the deactivation step.…”

Section: Final Remarksmentioning

confidence: 50%

“…Although such values are lower than that corresponding to ultramolecular weight (Ͼ1.5 ϫ 10 6 ), they are higher than that usually observed in the case of (iBuCp) 2 ZrCl 2 ), homogeneous, supported on silica or on MAO-modified silica. 44 MWD remained around 2.0.…”

Section: Polymer Propertiesmentioning

confidence: 95%

Supported hybrid catalysts based on zirconocene and tris(pyrazolyl)borate titanium derivatives

Pires

Gil

Rohrman

et al. 2005

J of Applied Polymer Sci

View full text Add to dashboard Cite

A series of hybrid supported catalysts were prepared by combining (iBuCp) 2 ZrCl 2 and {Tp Ms* }TiCl 3 complex (Tp Ms* ϭ HB(3-mesityl-pyrazolyl) 2 (5-mesityl-pyrazolyl) Ϫ ) sequentially grafted onto MAO (methylaluminoxane)-modified silica according to a Plackett Burmann 2 3 design. Supported catalysts were prepared taking into account the immobilization order, silica pretreatment temperature, and grafting temperature. Grafted metal content was comparatively determined by Rutherford backscattering spectrometry (RBS), X-ray photoelectronic spectroscopy (XPS), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The resulting catalysts were evaluated in terms of catalyst activity and polymer properties. According to RBS measurements, grafted metal content remained comprised between 0.1 and 0.5 wt % Zr/SiO 2 and 0.1 and 0.3 wt % Ti/SiO 2 depending on the immobilization order and on silica pretreatment temperature. All the systems were shown to be active in ethylene polymerization having external MAO as cocatalyst. Catalyst activity seemed to be governed by the zirconocene species, influenced slightly by Ti ones. Resulting polymers were characterized by DSC and GPC. The polyethylenes mostly presented higher molecular weight than those produced by homogeneous catalysts or by zirconocene grafted on bare or on MAO-modified silica.

show abstract

“…However, it should be added that, in relation to the data reported in the literature for the same metallocene catalysts immobilised on other silica supports, the efficiency of heterogenisation is inferior. [9,12] This more than likely results from the fact that, in our sol-gel silica product, some of the hydroxyl surface groups had been replaced with methyl groups. Therefore, in our case zirconocene is mainly monofunctionally bonded through isolated hydroxyl groups that are present on the surface (Scheme 1).…”

Section: Resultsmentioning

confidence: 95%

(Co)polymerisation Behaviour of Supported Metallocene Catalysts: Carrier Effect

Białek

Czaja

2006

Macro Chemistry & Physics

View full text Add to dashboard Cite

The polymerisation and copolymerisation of ethylene with 1-hexene over metallocene catalysts L 2 ZrCl 2 / MAO (L ¼ Cp, n-BuCp, t-BuCp, i-PrCp, Me 5 Cp) supported on different types of carriers (MgCl 2 (MeOH) 6 or silica with CH 3 surface groups obtained in the sol-gel process) were studied. It was demonstrated that both the metallocene structure and the type of inorganic support affected catalyst activity and polymer properties such as melting point, molecular weight and molecular weight distribution. The metallocene structure also determined comonomer incorporation, both for homogeneous and supported catalytic systems. When a catalyst is anchored on a support, it becomes less effective at incorporating a comonomer into the polyethylene chain, and the type of the support material has no influence on that process. The type of carrier used does, however, have an influence on the molecular weight and molecular weight distribution of the product obtained. Most polymers and copolymers obtained with catalysts supported on an oxide carrier have higher molecular weights and broader molecular weight distributions than those produced by catalysts anchored on a magnesium compound.Melting curves (obtained using the SSA method) of ethylene/1-hexene copolymers synthesised with Cp 2 ZrCl 2 /MAO (A) and with the same catalyst supported on various carriers (B,C,D).

show abstract

Ethylene polymerization with catalyst systems based on supported metallocenes with varying steric hindrance

Cited by 43 publications

References 25 publications

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Supported hybrid catalysts based on zirconocene and tris(pyrazolyl)borate titanium derivatives

(Co)polymerisation Behaviour of Supported Metallocene Catalysts: Carrier Effect

Contact Info

Product

Resources

About