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- W629136228 abstract "Methylaluminoxane (MAO) is one of the most important cocatalysts of metallocene catalysts. The yield and activity of MAO is low when using Al2(SO4)3 nH2O and other inorganic hydrates to synthesize methylaluminoxane. The repeatability of this reaction is not good. The product cost is very high because one of the raw materials (Trimethylaluminium, TMA) to prepare MAO is very expensive. In addition, on standing, MAO toluene solution tends to gel. Gelled MAO can not be used to prepare supported metallocene catalyets.With the development of gas phase and slurry polymerization of olefine by metallocene catalysts,the application of supported metallocene catalysts becomes more and more important.This paper relates to the use of trimethylaluminium (TMA), tri-isobutylaluminium(TIBA) and silica gel containing from about 4 to about 22 percent by weight absorbed water to synthesize modified methylaluminoxane (MMAO). This method, which integrates synthesis and supporting of MMAO, simplify the preparing process of metallocene catalysts. By using this method, the yield and activity of modified methylaluminoxane is higher than using Al2(SO4)3 nH2O and other inorganic hydrates, and what is more, not only the product cost is lowered, but also gelled MAO is avoided. In addition, the repeatability of this reaction is much better because TIBA is stabler than TMA.Synthesis of Modified MAO: A one liter three neck flask equipped with a magnetic stirring bar and a constant pressure funnel was charged with 250ml of dried and degassed toluene. 60g of undehydrated silica gel (Davison 955) which contains 12 weight percent absorbed water was added into the flask. The resulting mixture was stirred at -10℃ for 30 minutes. Thereafter 90ml of trimethylaluminum/toluene solution (2.0M) was dropped slowly into the flask in 60 minutes. The resulting mixture was allowed to react under stirring at -10℃ for 1hours, then at 0℃ for 1 hours,then at ambient temperature for 1 hours and finally at 40℃ for 5 hours. Thereafter 60ml of tri-isobutylalumini" @default.
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- W629136228 date "2004-01-01" @default.
- W629136228 modified "2023-09-24" @default.
- W629136228 title "Synthesis of Modified Methylaluminoxane" @default.
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