Magnesium dichloride

In addition to other polystyrene [138] and silica supports [139, 140, 141, 142, 143,144], iron and cobalt precatalysts have been immobilised on calcosilicate [145], magnesium dichloride [146,147,148,149], MCM-41 zeolite [150,151], clay [152] and fluorotetrasilicic mica [153], Supported systems have also been examined using alternative activators [154, 155, 156, 157, 158, 159]. For example, silica- and alumina-supported samples 5 have been activated with AK/ -Bu), to afford highly active, thermally robust catalysts [154], IR spectroscopy in DRIFT mode... 

In only a few polymerization processes are metallocene catalysts used in a soluble form. Supported metallocene catalysts are preferred for the production of polyethylene or isotactic polypropylene on an industrial scale, especially in the slurry and gas-phase processes. To use them in existing technological processes (drop-in technology) as replacements for the conventional Ziegler-Natta catalysts, the metallocenes have to be anchored to an insoluble powder support, including silica, alumina, and magnesium dichloride (208-217). Various methods of anchoring catalysts to supports are possible (Fig. 25) ... 

An alternative ionic equilibrium has been more recently proposed, based on the reactivity of magnesium dichloride in THF [30]. 

Tail, P.J.T. Zohuri, G.H. Kells, A.M. McKenzie, I.D. Kinetic studies in propene polymerization using magnesium dichloride supported 65. Ziegler-Natta catalysts. In Ziegler Catalysts. 

Ziegler catalyst derivative of a transition metal (such as titanium) md organoaluminium compound (such as triethylaluminium) supported on inorganic and organic support (such as silica, magnesium dichloride etc.)... 

A solid catalyst of active magnesium dichloride supported on titanium tetrachloride and solid electron-donor such as 2,2-diisobutyl-l,... 

In this review, data on the number of active centers and values of propagation rate constants (kp) for olefin polymerization on traditional ZN catalysts (mainly TiCl3/AIEt cCl3,) and highly active supported ZN catalysts containing titanium chlorides on activated magnesium dichloride will be presented. 

STUDIES IN SUPPORTED TITANIUM CATALYST SYSTEM USING MAGNESIUM DICHLORIDE-ALCOHOL ADDUCT... 

Present generation high activity Ziegler-Natta catalyst is comprised of titanium tetrachloride supported on magnesium dichloride [1-4]. Performance of the catalyst... 

The appropriate alcohol was mixed in stoichiometric amount with magnesium dichloride in hexane or decane. Reaction mixture was stirred for three hours. The solid product was filtered and washed with hexane and dried in vacuum for 30 minutes [Table 1]. 

The magnesium dichloride was reacted with 2-ethyl-1-hexanol (1 2 molar ratio) in decane at 120°C for two hours. A stoichiometric amount of dibutylphthalate (DBPh/MgCl = 0.15) was added in the reaction mixture and stirred for one hour at 120°C. The obtained solution was added into decane solution of diphenyl-dichlorosilane (Si/Mg molar ratio = 30) in controlled manner at room temperature. The reaction mixture was heated to 120°C and allowed to react for two hours. The solid product was separated by filtration and washed with hexane. It was treated with titanium tetrachloride (Ti/Mg molar ratio = 40) at 120°C for two hours. The liquid was decanted from reaction mixture at 120°C. The solid product obtained was washed with decane followed by hexane. Catalyst (Mg-Ti) was dried in vacuum for two hours. 

These results demonstrate that the molar ratios of reactants and stereo-electronic characteristics of alcohols control the stoichiometry of magnesium dichloride-alcohol adducts (Scheme 1). 

Scheme 1. Stepwise reaction of magnesium dichloride with alcohol.

Solid catalyst [Mg-Ti] was analyzed for its composition and specific surface area (Table 2). A 3.0 wt. % of titanium is incorporated on active support. BET surface area of crystalline magnesium dichloride is found to be 10 mVg. The treatment of magnesium dichloride with 2-ethyl-1-hexanol and DBPh followed by diphenyldichlorosilane gives a product [Mg-Ti I] with improved surface area characteristics (50 mVg). The reaction of [Mg-Ti I] with titanium tetrachloride increases the surface area to 115 m /g. These results show that the present process of catalyst synthesis gives approximately tenfold improvement in the surface area of the Mg-Ti catalyst as compared to the starting anhydrous magnesium dichloride. 

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