Borane-functionalized silica supports

Charoenchaidet, Sumate; Chavadej, Sumaeth; Gülari, Erdogan

doi:10.1016/s1381-1169(02)00002-x

Cited by 26 publications

(24 citation statements)

References 20 publications

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“…Tables 1 and 2 indicate that all the catalysts, independently on the ligand structures and the types of me- 1b, 1d, 1e, 1f, 0.13 mmol of 1a or 0.10 mmol of 1c) and salen complex of titanium/Et 2 AlCl (¢) catalysts (conditions: 0.08 mmol of complex 1b, 1c, 1e, 1f, 0.095 mmol of 1a or 0.03 mmol of 1d) tallic centres, produced polyethylene with the relatively low bulk density, i.e. in the range of 90-115 g/dm 3 , which however is about twice higher than that available with use of unsupported metallocene catalysts [34].…”

Section: Effect Of the Ligand Structure On Ethylene Polymerizationmentioning

confidence: 99%

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Białek

Czaja²

2008

Polimery

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Metal salen complexes as ethylene polymerization catalystseffect of catalytic system composition on its activity and properties of polymerization productsSummary -The series of salen-type complexes differing in the metal center (M = Ti, Zr, V) and in the coordination spheres (different substituent at salen ligands) after activation with methylalumoxane (MAO) or Et2AlCl were studied as catalytic systems in ethylene polymerization. The vanadium and titanium complexes were found to be more active in combination with alkylaluminum compound (Et 2 AlCl) then with MAO, while zirconium complex was active only in combination with MAO. The activity of complexes activated by Et2AlCl decreases in the order V > Ti >> Zr ≅ 0, and when MAO is used as the cocatalyst the activity changes the order: Ti > Zr > V. The substituent type in the salen ligand also affects the catalyst activity; the best results were obtained for the catalyst having Cl or Br as substituents. The type of substituent has no significant effect on polyethylene properties, while the type of cocatalyst and the type of metallic centre play here the essential role. The salen titanium complexes in combination with Et2AlCl usually produce low molecular weight polyethylene with narrow polydispersity, also accompanied by oligomers. Other catalytic systems give linear high molecular weight polyethylene (M w = 200 000-700 000).

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Section: Effect Of the Ligand Structure On Ethylene Polymerizationmentioning

confidence: 99%

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Białek

Czaja²

2008

Polimery

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“…Additionally, the modified support acted as a weakly coordinating polyanion to which the active cations are bound by electrostatic rather than covalent interactions. 13,50 The weak coordination caused insertion of monomer and subsequent polymer chain growth. C appeared in fairly comparable concentration.…”

Section: Resultsmentioning

confidence: 99%

“…The cross-polarization and magic angle spinning (CPMAS) 11,14 -18 and X-ray photoelectron spectroscopy (XPS) 19 which complement one another, have been used overall for characterizing supported (heterogenized) polyolefin catalysts. Cp supported on -alumina and magnesium chloride was characterized using 13 C CPMAS NMR spectroscopy. 14 -16 The generation of the thorocenium cation in the solid state was detected.…”

Section: Introductionmentioning

confidence: 99%

Surface chemistry of selected supported metallocene catalysts studied by DR-FTIR, CPMAS NMR, and XPS techniques

Atiqullah

Akhtar

Faiz

et al. 2006

Surf. Interface Anal.

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did not affect the solid-state electronic environment. However, it increased the surface cocatalyst to catalyst molar ratio (Al : Zr), acted as a spacer, increased catalyst activity, and enhanced chain-transfer reactions. The separately fed MAO cocatalyst shifted the equilibrium between Cation 1 and Cation 2 toward the right. Consequently, more Cation 2 was generated, which acted as the effective and active single-site catalytic species producing monomodal PDI.

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“…Hence, MAO cocatalyst-free polymerization is industrially desirable to achieve better resin bulk density, decrease the production cost, and overcome the aforementioned problems. [11][12][13][14] To the best of our knowledge, the hydrogen responsiveness of a supported metallocene catalyst, using MAO cocatalystfree ethylene polymerization, has not yet been reported in the literature. Therefore, the present study investigates the hydrogen responsiveness of the supported catalyst [Silica ES 70-n BuSnCl 3 / MAO/( n BuCp) 2 ZrCl 2 ] by polymerizing ethylene without separately feeding the MAO cocatalyst.…”

Section: Introductionmentioning

confidence: 99%

Supported SiO₂‐ⁿBuSnCl₃/MAO/(ⁿBuCp)₂ZrCl₂ catalyzing MAO cocatalyst‐free ethylene polymerization: Study of hydrogen responsiveness

Atiqullah

Moman

Akhtar

et al. 2007

J of Applied Polymer Sci

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A supported metallocene catalyst was synthesized by sequentially loading methylaluminoxane (MAO) (30 wt % in toluene) and ( n BuCp) 2 ZrCl 2 on partially dehydroxylated silica ES 70 modified by n BuSnCl 3 . Its shock load hydrogen responsiveness was evaluated by polymerizing ethylene for 1 h at 8.5 bar (g) and 758C without separately feeding the MAO cocatalyst. The shock load hydrogen feeding increased the ethylene consumption (at a fairly constant rate), catalyst productivity, as well as the resin bulk density and average particle size at DP (of hydrogen) $3.0 psi. The bulk density increased from 0.25 to 0.31 g/cm 3 . This shows a procedure for overcoming the inherent drop in catalyst productivity caused by heterogenization of metallocenes (that is a method for catalyst activation) and improving the resulting resin bulk density. The volume-weighted mean particle diameter of the resulting polyethylenes was found to be 5.80-11.12-fold that of the catalyst corresponding to DP 5 0.00-7.11 psi, respectively. The resulting kinetic profiles showed to be fairly stable. However, M w and polydispersity index were not affected. The particle size distribution, average particle size, and the scanning electron microscope photographs of the resulting resin particles confirmed the occurrence of the replication phenomenon. On the basis of the above findings, the mechanism of ethylene polymerization under the present experimental conditions has been revisited.

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Borane-functionalized silica supports

Cited by 26 publications

References 20 publications

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Surface chemistry of selected supported metallocene catalysts studied by DR-FTIR, CPMAS NMR, and XPS techniques

Supported SiO₂‐ⁿBuSnCl₃/MAO/(ⁿBuCp)₂ZrCl₂ catalyzing MAO cocatalyst‐free ethylene polymerization: Study of hydrogen responsiveness

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Borane-functionalized silica supports

Cited by 26 publications

References 20 publications

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization products

Surface chemistry of selected supported metallocene catalysts studied by DR-FTIR, CPMAS NMR, and XPS techniques

Supported SiO2‐nBuSnCl3/MAO/(nBuCp)2ZrCl2 catalyzing MAO cocatalyst‐free ethylene polymerization: Study of hydrogen responsiveness

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Supported SiO₂‐ⁿBuSnCl₃/MAO/(ⁿBuCp)₂ZrCl₂ catalyzing MAO cocatalyst‐free ethylene polymerization: Study of hydrogen responsiveness