Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond

Definitions

• Processes of this type are known to have a number of advantageous aspects compared to comparable other processes, but on the other hand also leave one or two wishes unfulfilled.
• This desire is particularly understandable in that, with increasing catalyst yield, polymers with a decreasing content of residual catalyst are obtained; - The latter should be as small as possible that a - complex - cleaning step to remove the residues can be omitted.
• the centerpiece is the use of a special chromium oxide supported catalyst, which is obtained from a specific intermediate catalyst product in two stages in a specific way.
• the catalyst intermediate as such is not associated with any special features; it can be one which is customary in the polymerization of olefins by means of supported chromium oxide catalysts.
• the preliminary product is based on a carrier which has a particle size of 0.02 to 3, in particular of C, 04 to 1.5 mm.
• the carrier consists of silicon dioxide or is a silicon dioxide which is chemically or physically linked to a component consisting of the elements aluminum, titanium, zirconium, molybdenum, vanadium or thor, which component is an oxide of the element concerned or one under the conditions step (1) into an oxide composition of the affected element.
• this (calculated as oxide) can make up to 20, in particular up to 15, percent by weight, based on the total weight of the carrier.
• Silicon dioxide mixed oxides which contain 0.1 to 15 percent by weight, based on the total weight of the carrier, of aluminum oxide are particularly suitable as carriers.
• the catalyst precursor i.e. the carrier loaded with a chromium compound, which is chromium trioxide or a chromium compound which converts to chromium trioxide under the conditions of stage (1), is treated in a known manner with oxygen in a first stage (1) in a certain manner as defined above . It is of particular importance that the solid is left in the form of a fluidized bed; - Where you can use such devices and procedures, as are common in fluidized bed processes. As has been shown, air is the preferred carrier gas. As has also been shown, the period of whirling is not critical, apart from the minimum period of 30 minutes, but should generally be 2 to 15 hours for convenience.
• the oxygen treatment in stage (1) is combined with treatment by a promoter.
• the promoters can be the relevant ones be usual, such as in particular ammonium silicofluoride '(NH 4 ) 2 SiF 6 , and can be added to the catalyst precursor before or during the vortexing.
• stage (2) the product obtained from stage (1), which is preferably flushed free of oxygen, is treated with carbon monoxide in a specific manner defined above and thus converted into the actual supported chromium oxide catalyst.
• stage (1) which is preferably flushed free of oxygen
• carbon monoxide in a specific manner defined above and thus converted into the actual supported chromium oxide catalyst.
• the solid is left in the form of a fluidized bed, and that the carrier gas is anhydrous and oxygen-free.
• Polymers of ethylene are produced using the new catalysts by means of the so-called “solution polymerization process”, cyclohexane in particular being considered as a solvent.
• solution polymerization process cyclohexane in particular being considered as a solvent.
• the polymerization process as such has no special features and can be carried out in the relevant customary technological configurations.
• a catalyst precursor consists of a homogeneously loaded silica / alumina mixed oxide containing chromium trioxide in a weight ratio of carrier: chromium trioxide of 100: 4.4, which contains 0.4 percent by weight, based on the total weight of the mixed oxide, and one Has particle size of 0.04 to 1.5 mm.
• This preliminary product is mixed with a promoter (ammonium silicon fluoride) in a weight ratio of catalyst preliminary product: promoter of 100: 2.5.
• promoter ammonium silicon fluoride
• a stirred autoclave is charged with 1000 parts by weight of cyclohexane, whereupon it is flushed with nitrogen and 0.1 part by weight of catalyst is added.
• a thermostatically controlled temperature of 150 ° C. pure ethylene is pressed up to a pressure of 35 bar, the process is continued until the pressure has dropped to 25 bar due to the formation of polyethylene, and then ethylene is pressed again up to a pressure of 35 bar and so on for 90 minutes.
• the polymerization is then terminated by cooling to room temperature and relaxing.
• a preliminary catalyst product consists of a silica / alumina mixed oxide loaded homogeneously with chromium trioxide in a weight ratio of carrier: chromium trioxide of 100: 2.0, which contains 0.1 percent by weight, based on the total weight of the mixed oxide, and one Has particle size of 0.04 to 1.5 mm.
• This preliminary product is mixed with a promoter (ammonium silicon fluoride) in a weight ratio of catalyst preliminary product: promoter of 100: 1.5.
• promoter ammonium silicon fluoride
• a catalyst pre-product consists of a silica / alumina mixed oxide loaded homogeneously with chromium trioxide in a weight ratio of carrier: chromium trioxide of 100: 4.5, which is 0.3% by weight, based on the total weight of the mixed oxide-aluminum oxide contains and has a particle size of 0.04 to 1.5 mm.
• Example 3 The procedure is as in Example 3, with the exception that the first stage (1) is carried out at a temperature of 570 ° C. (instead of 680 ° C.).
• Example 2 The procedure is as in Example 1, with the exceptions that a temperature of 146 ° C. (instead of 150 ° C.) is used and that instead of ethylene, a mixture of 98.5 parts by weight of ethylene and 1.5 parts by weight of butene-1 is polymerized .

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerization Catalysts (AREA)

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Citations (5)

• 1977
  • 1977-08-03 DE DE19772734909 patent/DE2734909A1/de active Pending
• 1978
  • 1978-07-21 IT IT7825982A patent/IT7825982A0/it unknown
  • 1978-07-28 EP EP78100534A patent/EP0000748A1/de not_active Withdrawn
  • 1978-07-31 FI FI782362A patent/FI782362A/fi not_active Application Discontinuation
  • 1978-08-02 JP JP9371178A patent/JPS5428380A/ja active Pending
  • 1978-08-02 DK DK342078A patent/DK342078A/da unknown
  • 1978-08-02 NO NO782639A patent/NO782639L/no unknown
  • 1978-08-02 AT AT559578A patent/ATA559578A/de not_active Application Discontinuation
  • 1978-08-03 ES ES472325A patent/ES472325A1/es not_active Expired

Patent Citations (5)

Non-Patent Citations (1)

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