Marcos A. S. Costa

The influence of some synthesis parameters on Ziegler-Natta catalyst performance

The role of di-n-butyl ether (DBE) in the synthesis of highly active and stereospecific catalyst for propylene polymerization has been investigated. The ether was used as internal base (IB) or complexed with TiCl4 and diethylaluminium chloride (DEAC) in iso-octane solution (System A) or complexed with triethylaluminium (TEA) in toluene solution (System B). Many differences were observed in the catalyst performance. The activity, the catalyst stereospecificity and the polymer bulk density were evaluated.

Effect of di-n-butyl ether on the synthesis of Ziegler–Natta catalyst for propylene polymerization

Abstract The influence of di-n-butyl ether (DBE) on the characteristics of Ziegler–Natta catalysts evaluated in propylene polymerization was investigated. The catalysts were synthesized by the reduction of TiCl 4 in toluene solution with AlEt 3 · DBE complex at various DBE/TiCl 4 mole ratios. The effect of DBE on the catalyst crystalline forms, determined by X-ray diffraction, was examined. The results show that a suitable amount of DBE leads to the formation of δ -TiCl 3 with high activity and enhanced stereoselectivity.

The role of hindered Lewis bases on the catalyst performance of TiCl3 for propylene polymerization

SummaryThe effect of AlEt3 modified by tributylamine (TBA), 1,4-diazabicyclo [2.2.2]octan (DO), 2,2,6,6-tetramethylpiperidine (TMPip), 2,6-dibutyl-4-methylphenol (BHT) and 2-tert-butyl-4-metoxyphenol (TBMP) on the propylene polymerization was studied using a catalyst based on TiCl3 modified with di-n-butyl ether as internal base. The influence of these hindered Lewis bases on the isotacticity, catalyst activity, molecular weight (

Characterization of Ziegler-Natta catalysts based on TiCl3 synthesized by different methods*

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Síntese de catalisadores Ziegler-Natta: algumas rotas e suas dificuldades

n) and molecular weight distribution (MWD) was investigated. It was verified that the Lewis bases modified the percentage of mm triad whereas no significant effect on I.I. was found.

Effect of reaction parameters on the polymerization of methyl methacrylate with nickel acetylacetonate/methylaluminoane

ABSTRACTThe effect of propylene (Pr), styrene (St), hexene-1 (He) and cyclopentadiene (Cp) employed in the preactivation of TiCl3 catalyst for propylene polymerization was investigated. The catalyst was synthesized by reduction of TiCl4 in toluene solution with AlEt3. DBE (di-n-butyl ether) complex. Catalyst activity and stereospecificity, soluble polymer content in the polymerization diluent were evaluated. The results show that the prepolymerization altered the catalyst performance and is influenced by the type of monomer employed in the preactivation step.

Polymerization of ethylene by chromium acetylacetonate/methylaluminoxane catalyst system

SummaryCatalysts based on TiCl3, modified by ethers, were prepared by different methods. Using di-n-butyl ether (DBE) as an internal base, complexes were formed in one-step reaction, either with TiCl4 and diethylaluminum chloride (DEAC) in iso-octane solution (System A) or with triethylaluminum (TEA) in toluene solution (System B). Diisoamyl ether (DIAE) and tetrahydrofuran (THF) were used as internal bases for the β-TiCl3 treatment during a three-step synthesis (System C). DIAE was also complexed with DEAC in a one-step synthesis in toluene solution (System D) or in iso-octane solution (System E). While the use of DIAE in the three-step synthesis has mainly led to the formation of γ-TiCl3 (System C), the use of DIAE in the one-step synthesis led to a highly active and stereospecific β-TiCl3 (Systems D and E). The type of solvent employed in systems A and B had a strong influence on the properties of the catalyst. Possible causes for the formation of different crystalline structures of TiCl3 are discussed by comparing the different routes of the TiCl3 synthesis.

Particle control of Ziegler–Natta catalysts based on TiCl3 for propylene polymerization. Effect of prepolymerization

Abstract A method was developed to prepare a crystalline structure of β-TiCl 3 (brown) using an electron-donor compound as an internal Lewis base, namely, diisoamyl ether (DIAE). β-TiCl 3 combined with triethylaluminium (TEA) resulted in highly active and stereospecific catalyst systems close to those based on violet TiCl 3 (α-, γ- or δ-TiCl 3 ) for propylene polymerization. The influence of solvent and amount of Lewis base employed in the catalyst synthesis on the catalyst properties and structure was investigated. The catalyst structure was examined by X-ray diffraction.