EP0002673A2
Expired / Lapsed
EP
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A process for activating a catalyst, catalyst and use of same for polymerisation of monoolefins
Assignee: Phillips Petroleum Co
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Filing: 1978-12-01
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Granted: —
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Expires: 1998-12-01
Abstract
Abstract High melt flow olefin polymers suitable for such applications as injection molding, and the like requiring a narrow molecular weight distribution are produced using a catalyst made by reducing and reoxidizing a chromium catalyst on either a titaniumsilica cogel or a self- reduced silica-containing composition. In the first embodiment. a cogel formed by coprecipitating silica and titania. and containing a chromium compound, is treated in a non-oxidizing atmosphere, such as CO, hydrogen, N 2 or a material decomposable to these materials, and thereafter reoxidized. In the second embodiment, a titanium-free chromium-containing catalyst is first heated in air or the like to dry the catalyst and oxidize the chromium after which it is heated in an inert atmosphere wherein the composition is self-reduced to give chromium in a lower valence state. The resulting selfreduced composition is then heated in a reducing ambient and then reoxidized as in the first embodiment.
Inventors
- 👤 Max Paul Mcdaniel
- 👤 Melvin Bruce Welch
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:25
CPC Classifications
B; B01; B01J; B01J37/00; B01J37/12; B01J23/00; B01J23/16; B01J23/24; B01J23/26; C; C08; C08F; C08F10/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
69 words
A process for activating a catalyst containing a base material prepared by coprecipitating a titanium compound and silica to form a cogel and containing chromium, characterized by a first step wherein said catalyst is contacted with a non-oxidizing ambient at a temperature of at least 600°C. and a subsequent second step wherein said catalyst is contacted with an oxidizing, oxygen-containing ambient at a temperature within the range of 450-1000°C.
Claim 2
Dependent Claim
69 words
A process for activating a catalyst containing a base material prepared by coprecipitating a titanium compound and silica to form a cogel and containing chromium, characterized by a first step wherein said catalyst is contacted with a non-oxidizing ambient at a temperature of at least 600°C. and a subsequent second step wherein said catalyst is contacted with an oxidizing, oxygen-containing ambient at a temperature within the range of 450-1000°C.
Claim 3
Dependent Claim
85 words
A process according to claim 1) characterized in that prior to said first step said catalyst composition containing at least a portion of said chromium in the form of CrO 3 in a set-reduction step is treated at a temperature of 600-1100°C. in an inert atmosphere for a time sufficient to achieve at least partial self-reduction of said chromium to a lower valence state and wherein said non-oxidizing ambient of said first step is a reducing agent under the conditions employed in said first step.
Claim 4
Dependent Claim
112 words
A process according to claim 2) characterized in that said catalyst is heated in air to a temperature within the range of 250-1000°C. over a time period of 20 minutes. to 10 hours, in that thereafter said self-reduction step is carried out in nitrogen at a temperature within the range of 700-925°C. for at least 5 minutes, in that said reduction step is carried out in an ambient comprising 2-100% carbon monoxide at a temperature of 700-925° C. for a time within the range of 1/2 to 24 hours and in that said reoxidation is carried out in air at a temperature within the range of 500-925°C. for 1/2 to 10 hours.
Claim 5
Dependent Claim
99 words
A process for producing a titanium-free silica base material and chromium comprising catalyst active for olefin polymerization wherein at least a portion of said chromium is in the form of CrO 3 characterized by subjecting said catalyst to an inert ambient for a time and at a temperature sufficient to self-reduce at least a portion of said Cr0 to a lower valence state, and thereafter subjecting the thus self-reduced composition to a reducing ambient at a temperature sufficient to further reduce at least a portion of said chromium, and thereafter reoxidizing the thus reduced composition in an oxygen-containing ambient.
Claim 6
Dependent Claim
99 words
A process for producing a titanium-free silica base material and chromium comprising catalyst active for olefin polymerization wherein at least a portion of said chromium is in the form of CrO 3 characterized by subjecting said catalyst to an inert ambient for a time and at a temperature sufficient to self-reduce at least a portion of said Cr0 to a lower valence state, and thereafter subjecting the thus self-reduced composition to a reducing ambient at a temperature sufficient to further reduce at least a portion of said chromium, and thereafter reoxidizing the thus reduced composition in an oxygen-containing ambient.
Claim 7
Dependent Claim
83 words
A process in accordance with claim 4) characterized in that said catalyst is subjected to said inert a temperature within the range of 600- ambient at a temperature within the range of 600-1100 C. for at least 5 minutes, and the resulting composition is contacted with said reducing ambient at a temperature within the range of 650-1100° C. for at least 5 minutes, and the thus reduced composition is contacted with an oxygen-containing ambient at a temperature within the range of 450-1000 C.
Claim 8
Dependent Claim
31 words
A process according to one of the preceding claims characterized in that said inert ambient is nitrogen, said reducing ambient comprises 2-100% carbon monoxide, and said oxygen- containing ambient is air.
Claim 9
Dependent Claim
29 words
A process according to one of claims 2) to 6) characterized in that said Cr0 is obtained by incorporating said chromium onto said base material as CrO 3 initially.
Claim 10
Dependent Claim
33 words
A process according to one of claims 2) to 6) characterized in that said CrO 3 is obtained by heating said catalyst to said temperature of 600-1100 C. in the presence of air.
Claim 11
Dependent Claim
37 words
A process according to one of the preceding claims characterized in that said chromium is present in an amount within the range of 0.1 to 5 weight per cent based on the weight of said base material.
Claim 12
Dependent Claim
11 words
A catalyst made in accordance with one of the preceding claims.
Claim 13
Dependent Claim
35 words
A polymerization process in which one or more monoolefins are contacted under polymerization conditions with a chromium and silica base material containing catalyst, characterized in that a catalyst as defined in claim 10) is used.
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