| 摘要 |
Ethylene is polymerized in a hydrocarbon fraction as reaction medium and with a catalyst comprising an aluminium alkyl compound and a compound of a Group IVa, Va or VIa metal, characterized in that the content of liquid constituents which boil at temperatures higher than the medium is maintained at less than 1% of the medium. The process may be batchwise or continuous and the use of purified aliphatic or hydroaromatic hydrocarbon fractions is specified. In an example a C7 to C9 fraction of boiling range 70-150 DEG C. is used and constituents boiling above 150 DEG C. are removed therefrom by distillation. The preferred process of the invention comprises the withdrawal of part of the reaction medium, the optional separation therefrom of residual catalyst (e.g. with nitric acid), followed by distillation, and then the recycling of the treated medium, preferably after a refining operation with concentrated sulphuric acid and water or alkali.
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