Claims
- 1. In a process for the preparation of a chromium oxide based catalyst supported on a granular or microspherical refractory oxide for use in the gas phase polymerisation of olefin(s), the improvement comprising subjecting a supported chromium oxide based catalyst to a sole calcination/activation step consisting of a single thermal treatment performed at a temperature ranging from 200 to 450° C. under an oxygen-containing atmosphere.
- 2. The process according to claim 1, wherein the single thermal treatment is performed at a temperature ranging from 300 to 400° C.
- 3. The process according to claim 1, wherein the oxygen-containing atmosphere is air.
- 4. The process according to claim 1, wherein the supported chromium oxide based catalyst is a titanium or aluminum modified supported chromium oxide based catalyst.
- 5. The process according to claim 4, wherein the supported chromium oxide based catalyst is a titanium modified supported chromium oxide based catalyst.
- 6. In a process for the gas phase polymerisation of at least one alpha olefin containing from 2 to 12 carbon atoms, performed with the aid of a chromium oxide based catalyst supported on a granular or microspherical refractory oxide, the improvement comprising, subjecting the catalyst, prior to its use in the polymerisation, to a sole calcination/activation step consisting of a single thermal treatment performed at a temperature ranging from 200 to 450° C. under an oxygen-containing atmosphere.
- 7. The process according to claim 6, further comprising recovering a polymer product having a melt index higher than a melt index of a polymer product produced by polymerizing the same alpha olefin using the same, polymerization conditions and catalyst composition, but wherein the catalyst has been subjected to a single thermal treatment performed at a temperature higher than 45° C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
97430023 |
Sep 1997 |
EP |
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Parent Case Info
This application is a continuation of International Application No. PCT/GB98/02674, filed Sep. 4, 1998, the content of which is incorporated herein by reference.
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RE35324 |
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Sep 1996 |
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Bailly et al. |
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Continuations (1)
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Number |
Date |
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Parent |
PCT/GB98/02674 |
Sep 1998 |
US |
Child |
09/522598 |
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US |