GB857181A - Improved polymerization catalyst - Google Patents

Abstract

Alpha olefins having 3-12 carbon atoms, specifically propylene, butene-1, 3-methylbutene-1, heptene-1, dodecene-1 or styrene, are polymerised by contact with a catalyst component activated with an alkylaluminium compound, particularly AlEt3, although other alkylaluminium compounds are also mentioned. The said component is TiCl3 cocrystallised with AlCl3, and which is prepared by reaction of TiCl4 with Al in an aromatic diluent (hydrocarbon or chlorinated hydrocarbon), removing the diluent in a washing zone and optionally washing with hydrocarbon, slurrying the reaction solids in a hydrocarbon, passing the slurry to a ball-milling zone, removing the hydrocarbon, dry ballmilling the solids and preferably slurrying the latter in a hydrocarbon. Polymerization is carried out in a hydrocarbon diluent; in isolating the polymer, a C1-4 alkanol such as isopropyl alcohol or n-butyl alcohol, preferably in combination with a chelating agent such as acetylacetone or diacetyl, is utilized as well as further alcohol, or an acid such as hydrochloric acid, for washing the product. Reference has been directed by the Comptroller to Specification 805,142.ALSO:TiCl3 cocrystallised with AlCl3 is prepared by reacting TiCl4 with Al powder in an aromatic diluent, passing the reaction mixture to a washing zone, removing the diluent, slurrying the reaction solids in a hydrocarbon, passing the slurry to a ball-milling zone, removing the hydrocarbon and dry ball-minling the reaction solids. The reaction solid may be (a) washed with a hydrocarbon prior to the slurrying step; (b) slurried in a hydrocarbon after ball-milling. Aromatic diluents specified are benzene, toluene, xylene, mesitylene, pseudocumene, ethylbenzene, cymene, tetralin, chloro- and dichloro-benzene and orthochlorotoluene, while the above-mentioned hydrocarbon may be the usual aliphatic, cycloaliphatic and aromatic solvents, including halogenated aliphatics and aromatics. For use as a catalyst, the cocrystallised product is activated with organometallic, particularly alkyl aluminium, compounds such as AlEt3, AlPr3, Al(i-Bu)3 and Et2AlCl; organo-aluminium compounds containing halogen, alkoxy, organic nitrogen or sulphur may also be used. The Specification refers to the following prior methods for preparing the cocrystallised product:- (1) reduction of TiCl4 with metal powders (Al,Ti); (2) reduction with metal alkyls (AlEt3) in a diluent above about 150 DEG C.; (3) heating TiCl4 + Al alkyl after the formation of a brown precipitate at above about 70 DEG C. in presence of a diluent; (4) reduction of TiCl4 with an Al trialkyl in a diluent, in temperature-graded stages rising about a 1:0.3 mole ratio of reactants; (5) reduction of TiCl4 vapour with hydrogen above 650 DEG C. in presence of AlCl3 vapours. Reference has been directed by the Comptroller to Specification 805,142.