| 摘要 |
A catalyst used in polymerizing ethylene is obtained by mixing an organometallic compound of aluminium or of a Group Ia, IIa or IIb metal with an organic or inorganic compound of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Th or U, then separating the precipitated, reduced, heavy metal compound formed and mixing same with an organometallic compound of aluminium or a Group Ia, IIa or IIb metal. In examples zinc diethyl, lithium butyl and a variety of aluminium compounds are used. The catalyst preparation is suitably effected in an aliphatic or aromatic hydrocarbon medium. Optionally the precipitated component of the catalyst has its activity reduced by pretreatment with oxygen or air. Specifications 799,392, 799,832 and 801,031 are referred to.ALSO:Ethylene is polymerized with a catalyst obtained by mixing an organometallic compound of aluminium or of a Group IA, IIA or IIB metal with an organic or inorganic compound of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Th or U, then separating the precipitated, reduced, heavy metal compound formed and mixing same with an organometallic compound of aluminium or a Group IA, IIA or IIB metal. In examples, zinc diethyl, lithium butyl and a variety of aluminium compounds are used. The catalyst preparation and the polymerization may be effected in an inert medium and specified are butane, hexane, cyclohexane, methyl-cyclohexane, heptane, octane, iso-octane, decahydronaphthalene, petroleum ether, Fischer-Tropsch hydrocarbon fractions, petroleum fractions, benzene, toluene and tetrahydronaphthalene. By pre-treating the precipitated heavy metal compound with air or oxygen, polyethylenes of lower molecular weights may be obtained. The addition, during the polymerization, of ethylene, of organometallic compound or of both catalyst parts is described. The products may be in the form of gritty powders and can be purified with acetone and dilute nitric acid. Specifications 799,392, 799,832 and 801,031 are referred to. |
