DE1568480A1 - Process for the production of linear olefins - Google Patents

Description

Esso Research and (4-573)

Engineering Company

Elizabeth, N.J./V.St.A.

Hamburg, December 8, 1966

Process for the production of linear olefins (addendum to patent (patent application E 32135 IVb / 120)

The main patent relates to a process for the preparation of linear olefins with an average molecular weight of about 70 to 300 by polymerizing an ethylene-containing gas in the presence of an essentially soluble catalyst, which is characterized in that the catalyst is; Reaction product of a transition metal halide of the formula TiX ₄ , TiX _x OR ¹ , or TiX ₃ OOGR ¹ , in which X is a chlorine or bromine atom and R 'is an alkyl, allyl, aralkyl or cycloölkyl radical, used with an alkylaluminium compound, where the conversion product has the general formula AlR _n Xy, in which H is an alkyl, Ar-'jlkyl- or cycloalkyl radical and X is a chlorine, Broff or iodine atom and η is less than 1 _} and the polymerization in the presence of a;.: polar aromatic hydrocarbon ^{or. -r · halogenated »*". 1} :., ar on: nt i already hydrocarbon ~ Lö: iun [- ;. ^ri .rii Lk Ι; / ". · 1 box oir .or 7 · :: mo <- vj tar utjterh ';.] h from " ⁷ ^" 0

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0.8 and the product containing at least 90% of linear olefins is isolated.

It is known (see U.S. Patent 2,993,94-2) that Hydrocarbon lubricating oils having a molecular weight in the range of 80 to 2000 by polymerizing ethylene under Use of a specific catalyst, specific diluent and compliance with specific temperatures can be obtained. The catalyst consists of a transition metal halide and a halogen-containing one Aluminum alkyl compound. In addition, it has been found that better yields of oil, greater catalyst reactivity and a more accurate maintenance of the molecular weight range can be achieved if the Reaction system for modifying the catalyst adds a small amount of a lower alkanol. Both that modified as well as the unmodified system described above lead to the formation of under the reaction conditions larger amounts of other products besides linear alpha-olefins, especially of olefins of type II (RGH-HGR), type III / \ and type IV

It is also known that ethylene can be converted into a product with a content under conditions which must be precisely observed

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of at least 90 mol of linear olefins with an average molecular weight of up to about 300 can polymerize. Such a process requires compliance with certain critical reaction conditions, which include the ratio of ethylene to end product, the use of a certain catalyst, the maintenance of temperatures below 25 ° 0 and certain pressure ranges. It has now surprisingly been found that ethylene can be polymerized to an end product with a content of at least 90 mol of linear olefins even at temperatures above 25 ° if a certain catalyst is used. The catalyst used according to the invention consists mainly of a soluble reaction product which is obtained ₉ when a reducible transition metal halide of groups IVB to VIB or VIII of the Periodic System of the Elements is partially reacted with an aluminum alkyl compound, so that the formula of the aluminum alkylene end product AlR _n X, _n is, where η is less than 1 ^ R is an alkyl, cycloalkyl or aralkyl radical with preferably 1 to 20 carbon atoms, for example a methyl, ethyl, isobutyl, cyclohexyl, or benzyl radical, and X is a chlorine, bromine or iodine atom. While most transition metal halides are suitable constituents of catalyst complexes if, according to the prior art, a branched-chain olefin is to be obtained as the desired product, it has now been found that compounds

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fertilizers such as VCl ₂ , and PeOl, are unsuitable for the production of linear alpha-olefins. The transition metal compounds preferably used for the catalyst according to the invention are trivalent or tetravalent, but preferably tetravalent titanium compounds, which can be represented by the following formula: TiX ₀ Aj ₃ , in which a = 3 or 4, b = 0 or 1 and a + b = 3 or 4-, where X is a chlorine or bromine atom and A is a chlorine or bromine atom or an anion derived ^{from a protonic compound, for example from an alcohol R 1} OH or a carboxylic acid R ^{1 COOH.} The radical R 'of the protonic compound can be an alkyl, aryl, aralkyl or cycloalkyl radical. The titanium compound TiX A ^ can be produced in situ by reacting TiX ₂ with the protonic compound. The preferred transition metal compound according to the invention belongs to the group TiX ^, TiX, OR 'and TiX ₅ OOGR ¹ . Typical examples of such compounds are TiCl ^, TiBr ^, TiX, OC ₂ Hc and TiX ^ OOCCH ,. The catalyst concentration is normally in the range from 0.1 to 10 g / l of diluent.

As already explained in more detail above, it is essential that the aluminum alkyl compound used as the catalyst after the reaction with the transition metal halide

Formula AlR ^ X, "has, in which η is less than 1. The η y— η *

Aluminum / titanium ratio can be approximately between 0.1: 1 to

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be more than 100: 1. The ratio of aluminum to Titanium is not critical. According to a preferred embodiment, the catalyst is by reacting a Monoalkylaluminiuradihalide with a transition metal halide manufactured. It is less convenient for small amounts of a dialkyl aluminum halide to be present in the reaction mixture, but it is important is that the dialkyl aluminum halide is no longer present in the catalyst made from this reaction mixture is. The catalyst must not contain traces of aluminum trialkyls.

With regard to the process of the invention, ethylene is unique in that other olefins cannot be converted into linear alpha-olefins in this way. It is therefore advantageous to use essentially pure ethylene or mixtures of ethylene with an inert gas as the starting material for the process according to the invention. Ethylene with a low content of other olefins can also be used, provided that polymerizations do not depress the linearity of the product below 90 % .

Alcohols can be used for modification, ₉ to influence the molecular weight of the product and the catalysts

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to enable, etc. However, the addition of alcohols is not necessary in the present process if the catalyst composition and the polymerization conditions are within a certain critical range. Usable. Alkenols are those having 1 to 8, preferably 1 to M carbon atoms. The improvement achieved through the use of the alkanol increases within the specified range with the molecular weight. It has also been found that the structure of the alkanol is important. For the various butanols, the yield increased noticeably on the transition from primary to secondary to tertiary alcohol. The selectivity for the polymeric oil (low average molecular weight) was also considerably higher for the secondary butanol and the tertiary butanol than for isobutanol. The alkanols that can be used accordingly include methanol, ethanol, n-propanol, isopropanol, n-butanol, sea-butanol, tert-butanol, isobutanol and all Oc and Og alcohols. 0 * to 0g diols in which the hydroxyl groups are not bonded to adjacent carbon atoms are also useful. Tert-butanol, sea-butanol, Ieo- or n-butanol and isopropanol are particularly preferred and favorable. These alkenols are used in small amounts, so that the ratio of ROH: R (based on aluminum alkyl) after the reduction of the transition metal is not greater than 0.5 and is preferably between 0.2 and 0.33

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Alkanol can be added to the transition metal halide as well to the alkyl aluminum halide before adding the second Component can be added. However, it is preferably added to the alkyl aluminum halide.

Although it is known that Lewis bases such as ethers or tertiary amines effective additives to Ziegler catalysts for the production of solid polymers at higher speeds their use in a mixture with the catalysts of the invention leads to a considerable loss of activity and lower selectivity for recovery of liquid linear olefins. It therefore appears that the Effect of the present catalyst under the conditions according to the invention completely different from that common catalysts is o

The subject of the present invention is a further improvement and development of the method according to the main patent | the process is characterized in that the polymerization is carried out in the presence of a non-polar aliphatic or naphthenic hydrocarbon or halogenated aliphatic or naphthenic hydrocarbon solvent. Mixtures of these solvents are also useful. Examples of preferred solvents' are methylene chloride, A'thylchlorid, Hethjlenchlorid (dichloromethane), heptane _f octane, hexane and mixtures thereof.

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A critical reaction parameter with regard to the selective synthesis of linear alpha-olefins is also the ethylene pressure. According to the prior art, highly branched olefins (60 #) are obtained when closely related Catalysts and solvents used at pressures from 0.5 to 2.1 atmospheres. It has now been established that an ethylene pressure of more than 3 »5 ata is essential for the production of linear olefins with high selectivity

Certain deviations are possible depending on the catalyst and solvent composition as well as the temperature, but the pressure is preferably above 5-6 to 7 ata in order to achieve economically interesting yields (at least above 5 wt. # and preferably above 10% by weight of olefins in the product withdrawn from the reactor) of linear alpha-olefins with a purity of more than about 90 % , the most preferred range being above 7 ata ethylene pressure

, Ethylene pressure can use the process because of the equipment requirements and become uneconomical because of the ethylene cycle.

The most critical reaction variable in the selective synthesis of linear olefins is the ethylene concentration, as was found. It has been found that the molar ratio of ethylene to product is above 0.8, preferably above about 2, must be so

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the selective synthesis of ethylene to linear olefins takes place. The upper limit of the molar ratio of ethylene on the other hand, the product is not critical. Bas molar ratio from ethylene to product must be above 0.8, because on the other hand the product formed contains more than 10 # branched chain olefins when looking at one product concentration works, which is necessary to achieve economically interesting yields.

The reaction time is not particularly critical as long as the reaction is carried out under the preferred conditions; it is normally in the range of 0 _f l to 5 hours if a product concentration of more than 5 wt.% to be obtained in the solvent. The process can be carried out batchwise or continuously, but the easiest way to achieve high product purities and high concentrations is to operate either batchwise or continuously with periodically interrupted current flow. The reaction vessel can be a long tube through which the solvent and catalyst flow together with the ethylene introduced at many points along the tube so that the desired ethylene concentration is maintained. In such a system, the monomer concentration need not be constant, since it can be set differently at different sections of the heating vessel in order to achieve the most favorable balance of activity _v

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Maintain molecular weight and product purity. Tanks with agitators can be operated in series to create a Approach to the implementation form described first to achieve.

The reaction according to the invention can be carried out by adding an alkali such as, for example, alkali or alkali metal hydroxide or carbonate, ammonium hydroxide and quaternary ammonium bases and Lewis bases such as ammonia, amines, cyclic bases Nitrogen bases, ethers, etc. are stopped to the reaction mixture. These alkalis can either be used alone or as a mixture or in solution in solvents such as water, alcohols or glycols.

The catalyst according to the invention enables the process for the preparation of linear olefins to be carried out at 3 ° temperatures below + 75 ° O, preferably between -30 ° and + 50 ° 0. Establishing a specified temperature within this range allows the average molecular weight of the product to be precisely determined. However, the wetting of the catalyst can also be used can be changed to influence the molecular weight.

To explain the present invention in greater detail the examples below serve.

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example 1

A solution of 0.5 millimoles of TiOl ^ in 75 ml of pure dry n-heptane was introduced into a 1 liter stirred autoclave under dry nitrogen at room temperature and heated to 50 ° warmed up. A solution of 0.5 millimoles of AlEtC ^ in 50 ml of n-heptane was admitted, followed by evacuation. After a reaction time of 30 minutes at 50 ° 0, the catalyst mixture was cooled to 0 ° G, whereupon ethylene of high purity until a pressure of 56.2 ata is reached in the reactor pressed in and then to 40 ° C within 5 minutes was heated. The temperature of 40 ° C and the pressure of 56.2 ata was maintained for 2 1/2 hours.

The reaction was carried out by forcing 5 millimoles of IJaOH into 100 ml of methanol ended “after the ethylene was blown off a small sample from the reactor washed twice with water, dried over IL ^ CO, and then gas chromatographed analyzed quantitatively. The remaining contents of the reaction vessel became about 2 parts by volume of isopropanol added, whereby waxy olefins precipitated. Filtering and drying in vacuo gave 8.6 g of wax.

Gas chromatographic analysis showed that the in cold Heptane soluble portion of the product more than 20 wt. # The Mixture and the yield was more than 22 g. The linearity of the product was more than 99 moles of linear alpha

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Olefins based on the Ono.po '"^ ⁰ ^^ ⁰¹¹ * ^The average molecular weight, calculated for a simple exponential distribution on the basis of gas chromatographic analysis, was 168.

Example 2

The procedure of Example 1 was repeated, but the reaction temperature was lowered to 20 ° 0. P The yield of wax was only 2.4 g and the total product had a lower molecular weight M _n than the product obtained according to Example 1 at 40.degree. It follows that the molecular weight also decreases as the reaction temperature decreases. This finding is in direct contrast to the observations on Ziegler catalysts.

Example 3

The procedure of Example 1 was repeated, but the catalyst of 2 millimoles of AlEtOIo and 1 millimole (EiCl ^, had been prepared, the reaction temperature at 0 ° C and the ethylene pressure was 42.2 ata. After 4 hours The reaction mixture contained 71 g linear reaction time alpha-olefins in the solution. The product purity was above 99 MoIJlS and the average molecular weight TL at 142.

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Example 4

The procedure of Example 2 was repeated, but using cyclohexane as the solvent instead of n-heptane was used. After a reaction time of two hours, the product concentration was 11.4% by weight and the alpha-olefin content of the product was 95 mol # and the average molecular weight was 185

Example 5

The procedure of Example 2 was repeated, wherein but 3-methylhexane instead of n-heptane as a solvent Was used. After a reaction time of two hours, the product concentration was 13.7 wt. The content of linear alpha olefins in the product was greater than 99 mol # and that average molecular weight M was 161.

These examples thus show that effective catalysts are obtained with an alkyl / Al ratio of 0 to 0.95 and an aluminum / titanium ratio of 0.5 * 1 to 104: 1. The catalyst activity, product purity (greater than 90 % linear alpha-olefins) and average molecular weight were all within the desired range. The ethylene / olefins recovered ratio was more than about 2 "Inr; benondero, the examples given show that the Umcotzunc; in non-polar aliphatic or naphthenic Löfjungßinmittel can be carried out with good success.

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Claims (8)

(4-573) Esso Research and Engineering Company Jk. Elizabeth, N.J./V.St.A. Hamburg, December 8, 1966 Claims 1. A process for the preparation of linear olefins with an average molecular weight of about 70 to 300 by polymerizing an ethylene-containing gas in the presence of an essentially soluble catalyst, in which the catalyst used is the reaction product of a transition metal halide of the formulas TiX _x ,, ₅ ¹ , or TiX ₅ OOOR ¹ , in which X is a chlorine or bromine atom and R ^{1 is} an alkyl, allyl, aralkyl or cycloalkyl radical, is used with an alkylaluminum compound, this reaction product having the general formula AlR _n X ^ _n , in which R is an alkyl, aralkyl or cycloalkyl radical and X is a chlorine, bromine or iodine atom and η is less than 1, and the polymerization in the presence of an inert solvent at a temperature below 75 ° 0 and under a pressure above 3.5 ata and with a molar ratio of ethylene to reaction product of above 0.8 through 109810/7 172 - ä- - leads and isolates the product containing at least 90 % of linear olefins, according to patent ....... (patent application E 32 135 IVb / 120), characterized in that the polymerization is carried out in an aliphatic or naphthenic hydrocarbon or in a halogenated aliphatic or naphthenic hydrocarbon solvents. 2. The method according to claim 1, characterized in that the transition metal halide is TiCl ^. 3. The method according to claim 1, characterized in that the ratio of. Ethylene to reaction product is above about 2. 4. The method according to claim 1, characterized in that an ethylene-containing gas in the presence of a substantially soluble, prepared from TiCl ^, and ethylaluminum dichloride catalyst of the general formula Al (GgHn) ₁₁ Ol ₇ , in which η is less than 1 is polymerized in the solvent, the temperature below 75 ° G, the pressure above 7 aaa and the molar ratio of ethylene to reaction product above about 2, and a product containing at least 90 mol of linear alpha-olefins is isolated. 109810/717 ") 5. The method according to claim 1-4, characterized in that the solvent is a saturated hydrocarbon used. 6. The method according to claim 1-5 »characterized in that one works at a pressure of more than 35 a ^ a. 7. The method according to claim 4, characterized in that the proportion of reaction product is more than 5 wt W on solvent and reaction product. 8. The method according to claim 4, characterized in that the temperature is between -30 ° and + 50 ° G. coll: ro 1 η / - ¹ ι ■ / · <