| 摘要 |
Mfr. of an olefin polymerisation catalyst comprises; (a) a mixt. as a support contg. at least one cpd. A chosen from oxides of gps. IVb and IIIa, IVa elements with at least one chromium salt. (b) preactivation of the mixt. by heat in an oxidising atmos. at a temp. less than the fusion temp. of the chromium salt to give a precursor. (c) activation of this precursor by calination in oxidising atmos. in the condition that part of the chromium is coverted to hexavalent chromium. The support, pref. contains a cpd. A, for example, silica, alumina, aluminium phosphates or mixts. of these. It is also pref. that the support contains at least one cpd. B having an element from gp. IVb and IIIa and the cpd. B is different from A. Cpd. A is a particle bed in the support and is treated with a gas comprising cpd. B during fluidisation. Cpd. B is pref. TiCl4. After treatment, the mixed cpd. formed is preactivated. Chromium salts are organic salts, pref. chromium acetylacetonate present at 0.05-10% by wt. ratio to total mixt.. |
