WO2004018388A1

WO2004018388A1 - Combined method for the selective production of $g(a)-olefins

Info

Publication number: WO2004018388A1
Application number: PCT/EP2003/009168
Authority: WO
Inventors: Veronika Quaschning; Alexander Hauk; Dag Wiebelhaus
Original assignee: Basf Aktiengesellschaft
Priority date: 2002-08-20
Filing date: 2003-08-19
Publication date: 2004-03-04
Also published as: DE10238027A1; AU2003266994A1

Abstract

The invention relates to a method for the production of α-olefins from olefins which have internal double bonds, comprising the following steps a) reacting an olefin with an internal double bond with a trialkylaluminium compound (A) in the presence of a catalyst in order to form a corresponding trialkylaluminium compound (B), wherein at least one of the alkyl groups which is connected to the aluminium is an alkyl group which is derived from α-olefin, and b) separating the reaction mixture obtained in step a) from the used catalyst, and c) reacting the trialkylaluminium compound (B) formed in step a) with an olefin by displacing the desired α-olefin, whereby the reaction in step c) takes place thermally. The invention also relates to a method for the production of a trialkylaluminium compound (B) in the presence of a heterogeneous catalyst and the use of a heterogeneous catalyst as a catalyst for isomerisation transalkylation.

Description

Combined process for the selective production of α-olefins

The present invention relates to a process for the selective production of C ₄ - to C ₃₀ -α-olefins by isomerizing transalkylation of C ₄ - to C ₃₀ -olefins with an internal double bond and subsequent release of the desired C ₄ - to C ₃₀ -α-olefin ,

Due to their carbon double bond, via which the introduction of a large number of functional groups is possible, olefins represent the most important class of basic chemicals for the chemical industry. For olefins which, as is known to the person skilled in the art, are divided into different classes, for example in short - And long-chain, linear and branched olefins or olefins with internal and terminal double bonds (α-olefins), there are different manufacturing processes. A frequently used process for the production of olefins is the cracking of saturated hydrocarbons. However, this is particularly suitable for the production of short-chain olefins in the carbon number range up to a maximum of 4.

Linear, higher α-olefins with 4 to 30 carbon atoms represent a class of olefins which have found a wide range of uses, inter alia, as comonomers and as raw materials for surfactants, lubricants or plasticizers. There are only a limited number of manufacturing processes for this class of olefins. The dehydration of natural alcohols and the cracking of higher paraffins (wax splitting) are insignificant. The majority of linear olefins are produced by transition metal-catalyzed oligomerization of ethylene using the Ziegler process or the so-called SHOP process of the Shell, which enables highly linear olefin fractions with an olefin content of> 95% to be obtained. In the Ziegler process, aluminum alkyls serve as catalysts, and in the SHOP process, phosphine-modified nickel complexes are used as active species in the oligomerization reaction. The need for olefins with terminal double bonds (α-olefins) is much greater than for olefins with internal double bonds. For example, 1-hexene and 1-octene are required as comonomers for polyethylene, while 1-decene is used for the production of synthetic lubricants. However, since olefins with internal double bonds are thermodynamically more stable than olefins with terminal double bonds (α-olefins), numerous processes for the production of long-chain olefins such as the dehydration of alcohols or alcohol mixtures, the dehydration of linear paraffins, the olefin metathesis or disproportionation of olefins Olefins with internal double bonds are formed, which then have to be converted into the more sought-after α-olefins.

EP-A 0 525 760 and EP-A 0 505 834 relate to a process for the production of aluminum alkyls and linear α-olefins from olefins with an internal double bond. An olefin with 4 to 30 carbon atoms, which has an internal double bond, is isomerized on a homogeneous catalyst, in particular on nickel, and this olefin is reacted with trialkyl aluminum. This displaces the olefin originally bound to the aluminum. The formed aluminum trialkyl compound, in which at least one radical is formed from a C ₄ - to C ₃ o-α-olefin, is then transferred to a release step which is carried out in the presence of a displacement catalyst. In the release step, the desired C - to C ₃ o-α-olefin is released. In order to avoid back-isomerization of this olefin to an olefin with an internal double bond, the displacement catalyst, which generally corresponds to the catalyst in the preceding isomerizing transalkylation, must be deactivated by adding an inhibitor, in particular lead. The deactivated displacement catalyst must be removed at the end of the reaction.

To avoid back-isomerization of the desired α-olefins to olefins with internal double bonds, it is desirable to carry out the release of the desired α-olefin from the trialkylaluminum compound in the absence of catalysts. The thermal release of olefins from trialkyl aluminum compounds is known.

No. 3,277,203 relates to a process for the production of olefins, in which a trialkylaluminum compound with an α-olefin having a low molecular weight important is implemented to release an olefin from the trialkylaluminum compound. The process is carried out at a temperature of about 260.degree. C. to 315.degree. C. for a reaction time of 0.5 to 1.1 seconds in the presence of a liquid hydrocarbon as a solvent which is intended to avoid the decomposition of aluminum trialkyl at the temperatures mentioned.

US Pat. No. 5,157,190 and US Pat. No. 4,935,569 relate to processes for the preparation of C ₆ -C 1 -α-olefins, in which the desired α-olefin is displaced from aluminum trialkyl by butene or by butene and ethene in the absence of catalysts at temperatures of 260 to 340 ° C and pressures from 4 to 120 bar in a static mixer with residence times of preferably 0.1 to 0.5 seconds.

No. 3,391,219 likewise describes a thermal displacement of a desired α-olefin from a trialkyl aluminum compound, an olefin being reacted with the trialkyl aluminum compound at 280 to 320 ° C. The reaction mixture is then rapidly cooled to 120 ° C. in order to avoid undesired side reactions.

All of the processes mentioned have in common that the thermal release takes place after an aluminum trialkyl-catalyzed oligomerization of ethylene by the Ziegler process. This means that only trialkylaluminum compounds, olefins and optionally solvents are present in the reaction mixture which is in the release stage.

The object of the present invention is to provide a process for the preparation of C - to C ₃₀ -α-olefins from C ₄ - to C ₃ o-olefins with internal double bonds, firstly an isomerization of the C ₄ - to C ₃₀ - olefins with internal Double bonds occur on a catalyst and the resulting isomerized C ₄ - to C ₃₀ -α-olefins displace alkyl residues from a trialkyl aluminum compound, so that trialkyl aluminum compounds are formed in which at least one of the alkyl groups bonded to the aluminum contains one of the desired C ₄ - to C ₃₀ -α-olefin derived alkyl group, and subsequent catalyst-free release of the desired C - to C ₃₀ -α-olefin. The difficulty with this process is that the first stage (isomerization and transalkylation, hereinafter referred to as isomerizing transalkylation) takes place in the presence of a catalyst which simultaneously re-isomerizes the desired C ₄ - to C ₃₀ -α-olefins to olefins with internal double Binding catalyzes if it is present in the release stage. This problem is solved, for example, in EP-A 0 525 760 and EP-A 0 505 834 in that the nickel catalyst used both in the isomerization and in the release stage is deactivated in the release stage by adding lead or lead compounds, to avoid back isomerization.

According to the present invention, this object is achieved by a process for the preparation of C - to C ₃₀ -α-olefins from C ₄ - to C ₃₀ -olefins with internal double bonds, comprising the following steps:

a) Reaction of a C ₄ - to C ₃ o-olefin with internal double bond or a mixture of C ₄ - to C ₃₀ -olefins with internal double bonds with a trialkylaluminum compound (A) in the presence of a catalyst for isomerizing transalkylation to form a C - to C ₃₀ -α-olefins or a mixture of C ₄ - to C ₃₀ -α-olefins which displaces the corresponding alkyl radicals from the trialkylaluminum compound (A), which are released as the olefins corresponding to the alkyl groups, the C ₄ - bis C ₃₀ -α-olefin attaches to the aluminum to form a corresponding trialkylaluminum compound (B), wherein at least one of the alkyl groups bonded to the aluminum is an alkyl group derived from the C ₄ - to C ₃₀ -α-olefin, and

b) separation of the reaction mixture obtained in step a) from the catalyst used for the isomerizing transalkylation, and

c) reaction of the trialkylaluminum compound (B) formed in step a) with an olefin with displacement of the desired C ₄ - to C ₃₀ -α-olefin,

wherein the reaction in step c) takes place thermally, in the absence of catalysts. The process according to the invention has the advantage that back isomerization of the desired α-olefins by the presence of a catalyst for isomerizing transalkylation during the displacement (step c)) is avoided. Furthermore, it is optionally possible to reuse the catalyst separated in step b) for the isomerizing transalkylation in step a), since this was not deactivated by the addition of lead or lead compounds in order to avoid re-isomerization in the release stage.

For the purposes of the present application, α-olefins are understood to mean olefins with a terminal double bond (terminal double bond).

Trialkyl aluminum compounds (A) are the trialkyl aluminum compounds used in step a) of the process according to the invention, while trialkyl aluminum compounds (B) are the trialkyl aluminum compounds obtained in step a) in which at least one of the alkyl groups bonded to the aluminum is one of the desired ones C - to C ₀ -α-olefin derived alkyl group.

For the purposes of the present application, step a) of the process according to the invention is referred to below as "isomerizing transalkylation", and step c) is referred to as displacement.

For the purposes of the present application, “isomerizing transalkylation” means the reaction of an olefin with an internal double bond with a trialkylaluminum compound (A) under isomerizing conditions, that is to say in the presence of a catalyst for isomerizing transalkylation. The olefin with an internal double bond rearranges with double bond isomerization to a mixture of olefins with an internal double bond and α-olefins (i.e. olefins with a terminal double bond), only the α-olefins reacting to form a trialkylaluminum compound (B). This releases an olefin that corresponds to the alkyl radical that was previously bound to the aluminum.

The C - to C ₃₀ -olefins used in the reaction in step a) with internal double bonds can be used in pure form or in a mixture with C ₄ - bis

C ₃₀ -α-olefins and / or with paraffins are present. Are the C ₄ - to C ₃₀ -olefins with internal double bonds in a mixture with C - to C ₃₀ -α-olefins or used with paraffins, the mixture preferably contains up to 5% by weight of C ₄ -C ₃₀ -α-olefins and / or less than 50% by weight of paraffins.

With the aid of the method according to the invention, C ₄ - to C ₃ o-α-olefins, preferably C - to C ₁₄ -α-olefins, particularly preferably C ₆ - to Cio-α-olefins, which are in particular linear, are accessible. For the purposes of the present application, the α-olefins mentioned include both olefins with a certain number of carbon atoms and mixtures of olefins with different carbon numbers. Linear α-olefins such as 1-butene, 1-hexene, 1-octene and 1-decene are very particularly preferably produced using the process according to the invention.

Suitable olefins with an internal double bond are the olefins corresponding to the desired α-olefins in terms of carbon number. Ice and trans-2-butene, ice and trans-2-hexene, ice and trans-3-hexene, mixtures of hexenes with an internal double bond, 2-, 3- and 4-octene and mixtures of octenes are particularly suitable with internal double bond as well as 2-, 3-, 4- and 5 -decene and mixtures of decenes with internal double bond.

Processes for the production of olefins with an internal double bond are known to the person skilled in the art. Suitable processes are, for example, the dehydration of alcohols or alcohol mixtures, the dehydration of paraffins and the metathesis or disproportionation of olefins.

The olefins with internal double bonds are preferably obtainable by the dehydrogenation of linear paraffins or by olefin metathesis. Processes for the production of olefins with internal double bonds by olefin metathesis are, for example, in the unpublished patent applications (official file number: DE 101 36 048.7) and (official file number: DE 101 03 309.5), which are integral parts of the present application, available.

Particularly preferred processes for the preparation of the olefins having an internal double bond are processes based on C ₄ fractions which are obtained in steam or FCC cracking or in the dehydrogenation of butane. Raffinate II is preferably used as the C ₄ fraction, the C ₄ stream being treated appropriately on adsorber protective beds, preferably high-surface A aluminum oxides and / or molecular sieves, freed from troublesome impurities, especially oxigenates. Raffinate II is obtained from the C ₄ fraction by first extracting butadiene and / or subjecting it to selective hydrogenation. After separation of isobutene, raffinate II is then obtained. The raffinate II obtained is then converted directly or after further refinement steps, preferably by metathesis to the desired olefins with an internal double bond.

Step ά): isomerizing transalkylation

Preferred trialkylaluminum compounds (A) are those whose alkyl radicals have fewer carbon atoms than the olefins used with internal double bonds (if an olefin mixture with internal double bonds is used, the alkyl radicals of the trialkylaluminum compounds preferably have fewer carbon atoms than the average carbon number of the olefin mixture with internal Corresponds to double bonds). The olefin liberated from the trialkylaluminum compound (A) in step a) preferably has a lower boiling point than the desired α-olefin or the olefin used as a starting product with an internal double bond, since the olefin liberated from the trialkylaluminum compound (A) is preferably continuous is removed from the reaction mixture and thus leads to an acceleration of the reaction by shifting the reaction equilibrium. Suitable trialkyl aluminum compounds (A) have alkyl groups with 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms, such as triethyl aluminum, tri-n-propyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, trineo-hexyl aluminum. Trialkylaluminum compounds are preferably used whose alkyl chains are straight-chain, particularly preferably those whose alkyl groups do not isomerize after release, such as tri-n-propylaluminum.

The trialkylaluminum compounds (A) preferably have a low hydride content, generally less than 1.0% by weight, preferably less than 0.1% by weight, since the catalyst for isomerizing transalkylation can be quickly deactivated in the presence of aluminum hydrides.

Suitable catalysts for isomerizing transalkylation are both homogeneous and heterogeneous catalysts. These catalysts generally contain common as active metals transition metals such as cobalt, chromium, nickel, molybdenum, iron, rhodium, iridium, palladium or platinum, titanium, hafnium or zirconium or mixtures of the above-mentioned active metals. Transition metals from the group consisting of cobalt, chromium, nickel, iron, rhodium, iridium and molybdenum or mixtures of the metals mentioned, such as cobalt / chromium, are particularly preferably used. Nickel is very particularly preferably used.

Suitable homogeneous catalysts are cobalt complexes, titanium or zirconium alkoxylates, for example Ti (OBu) ₄ and Zr (OBu) ₄ , as well as nickel (II) salts, nickel (II) carboxylates, nickel (II) acetonates or nickel ( 0) complex. Suitable nickel (II) salts are the chlorides, bromides or iodides of nickel. Suitable nickel carboxylates are nickel acetate, nickel 2-ethylhexanoate and nickel naphthenate. A suitable nickel acetonate is, for example, nickel acetylacetonate. Suitable nickel (0) complexes are Ni (CO) ₄ , nickel-bis-l, 5-cyclooctadiene (Ni (COD) ₂ ), Ni (C ₂ H ₄ ) ₃ , Ni (norbonen) ₃ , nickel-cyclododecatriene or nickel (0) complexes in which trivalent phosphorus compounds are used as ligands, such as Ni (PPh ₃ ) ₄ , Ni (PEt ₃ ) ₄ , Ni (P (OEt) ₃ ) ₄ and Ni (P (SiMe ₃ ) ₃ ) ₃ . The compounds mentioned, which are suitable as catalysts for the isomerizing transalkylation, can be prepared by processes known to those skilled in the art and some of them are commercially available.

Heterogeneous catalysts, particularly preferably heterogeneous catalysts containing nickel, are preferably used in the process according to the invention. Suitable heterogeneous catalysts contain transition metals such as nickel, cobalt, molybdenum, chromium, palladium or platinum on an inert support or in the form of their oxides, for example nickel (II) oxide. Heterogeneous catalysts are particularly preferably used, which are fixed on an inert support in such a way that washing out of the active metal component during the reaction is avoided. This can be achieved, for example, by using a catalyst in which the support material and the active species (generally a metal (ligand) complex) are linked via a chemical bond. The metal complex can, for example, be linked to the inert support material via alkoxysilyl groups present on the ligands. Furthermore, it is possible to link the active species to the support material via transition metal complexes of ethylenediamine or EDTA. Suitable transition metal complexes are nickel-ethylenediamine or nickel-EDTA complexes. As another Ligands are ligands with one or more N-, P- or S-containing functional groups or diimino complexes, for example bidentate diimino complexes as disclosed in EP-A 1 134 236, are suitable in order to fix the active metal component well on the To achieve carrier material. The preparation of the ligands mentioned and the corresponding transition metal complexes is known to the person skilled in the art.

All inert carrier materials usually used are suitable as inert carrier materials. Inorganic solids are preferably selected from the group consisting of SiO ₂ , α- or γ-Al ₂ O ₃ , SiO ₂ -Al O ₃ , ZrO ₂ , TiO ₂ , MgO, CeO ₂ , La ₂ O ₃ , activated carbon and aluminum phosphates as well Mixtures thereof, particularly preferred are SiO ₂ , Al O ₃ and / or TiO ₂ .

Furthermore, the heterogeneous catalysts can additionally contain modifiers, e.g. to avoid washing out the active metal component or increasing the activity of the isomerizing transalkylation catalyst.

The preparation of the heterogeneous catalysts mentioned is known to the person skilled in the art.

Examples of suitable heterogeneous catalysts and their production processes are in GQ Lu et al., Chemtech. (1999), 37 (nickel on metal oxides (α-, γ- Al ₂ O ₃ , La ₂ O ₃ , MgO, SiO ₂ , TiO ₂ , CeO ₂ ), activated carbon, alumina and zeolites), ZX Cheng et al. Stud. Surf. Be. Catal. 91 (1995) 1027 (Ni / SiO ₂ catalyst, produced using nickel-ethylenediamine chelate ligands), J. Ryczkowski, Adsorpt. Be. Technol. 14 (2) (1996) 113 (Ni / γ-Al ₂ O ₃ , the carrier material being modified with ammonia and / or with organic compounds, in particular EDTA) and BH Lipshutz, Adv. Synth. Catal. 343 (4) (2001) 313 (nickel on activated carbon).

If a homogeneous catalyst is used as the catalyst for the isomerizing transalkylation, this is generally used in an amount of 0.01 to 5 mol%, based on the trialkylaluminum compound (A) used, preferably 0.02 to 1.0 mol%. If a heterogeneous catalyst is used, the amount of the active metal component in the heterogeneous catalyst is generally 0.1 to 70 wt .-%, preferably 1 to 30 wt .-%, of the oxide, based on the total catalyst mass.

In principle, the heterogeneous catalyst can be used in any form, with use in the form of a fixed bed being preferred, in particular when the process according to the invention is carried out continuously.

The isomerizing transalkylation catalyst in step a) is preferably first mixed with the olefins used with internal double bonds, and this mixture is then added to the trialkylaluminum compound (A) used. However, it is also possible to add the isomerizing transalkylation catalyst to a mixture of trialkylaluminum compound (A) and olefin with an internal double bond. The catalyst can be added in a solvent or without a solvent. Suitable solvents are known to the person skilled in the art.

In a preferred embodiment of the process according to the invention, the olefin liberated from the trialkylaluminum compound (A) in step a) of the process according to the invention is removed as a vapor from the reaction mixture, as a result of which the transalkylation with the α-olefin formed by isomerization, which is one of the original alkyl groups of the trialkylaluminum compound (A) displaced, accelerated by shifting the equilibrium. The alkyl group displaced in the form of an olefin from the trialkylaluminum compound (A) can be used again in step c) of the process according to the invention as an olefin to displace the desired α-olefin. Unreacted olefins with internal double bonds can be separated from the reaction mixture, for example by distillation or stripping in vacuo, and used again in the isomerizing transalkylation (step a)).

Step a) is generally carried out at temperatures from -20 ° C. to 200 ° C., preferably 30 ° C. to 100 ° C. The reaction pressure is generally 0.1 to 20 bar, preferably 0.5 to 8 bar and the reaction time is generally 0.1 to 2 hours. The ratio of the olefins used with internal double bonds to the trialkylaluminum compound (A) is generally from 1 to 40: 1, preferably from 5 to 15: 1, particularly preferably from 8 to 10: 1.

The process according to the invention can be carried out in the presence of solvents, but this is not necessary. Suitable solvents are inert aliphatic and aromatic hydrocarbons which have a boiling point suitable for the reaction conditions (reaction temperature). Suitable solvents are, for example, isoheptane, heptane, octane, isooctane, dodecane and isododecane.

Step b): separation of the reaction mixture obtained in step a) from the catalyst used for the isomerizing transalkylation

The catalyst used in step a) for the isomerizing transalkylation catalyzes both the isomerization of olefins with internal double bonds to α-olefins and the re-isomerization of α-olefins to the thermodynamically more stable olefins with internal double bonds. It is therefore necessary to deactivate or separate the catalyst before displacement (step c)). According to the process of the present application, the isomerizing transalkylation catalyst is separated in step b).

If homogeneous catalysts are used, they can be separated off using various methods, which can be used individually or in combination of two or more methods:

■ Adsorption of the homogeneous catalyst, for example by means of activated carbon, aluminum oxide, SiO ₂ , organic resins, for example styrene / divinylbenzene or polysiloxanes or by means of ion exchangers which are, for example, slightly acidic or basic;

Magnetic deposition, e.g. nickel (ferromagnetic);

^■ electrostatic;

^■ electrochemical;

■ thermally, for example by agglomeration; ^■ precipitation of the catalysts and subsequent separation of the precipitated catalyst, for example by filtration, decantation or centrifugation, preferably by passing the supernatant through a membrane; ^■ Conversion to volatile carbonyl compounds.

The individual processes are known to the person skilled in the art. The separation is preferably carried out by adsorption of the homogeneous catalyst.

The removal of the catalyst is considerably simplified if a heterogeneous catalyst, which is preferably used in step a), is used. This can e.g. separated from the reaction mixture by simple filtration, decanting or centrifuging and can be used again in step a). If the heterogeneous catalyst is used in the form of a fixed bed, it is not necessary to separate the catalyst from the reaction mixture by filtering, decanting or centrifuging, since in this case the reaction mixture is passed over the catalyst and the catalyst remains in the fixed bed after the reaction, so that the reaction mixture is separated from the fixed bed catalyst by simply passing the reaction mixture over the fixed bed. The use of a heterogeneous catalyst in the form of a fixed bed is particularly preferred if the process according to the invention is carried out continuously.

Step c): Displacement of the desired oil

In step c), the desired C ₄ - to C ₃₀ -α-olefin is displaced from the trialkylaluminum compound (B) formed in step a) of the process according to the invention. According to the invention, the displacement takes place thermally, in the absence of a catalyst. For this purpose, the trialuminium alkyl compound (B) is reacted with an olefin in a molar ratio of generally 1: 1 to 1:20, preferably 1: 2 to 1:10. Suitable olefins are α-olefins with generally 2 to 18 carbon atoms or mixtures thereof. The α-olefin which was released in step a) from the trialkylaluminum compound (A) is preferably used. The trialkylaluminum compound (A) used in step a) is thus reformed in step c) and can in turn be used in step a) of the process according to the invention. The thermal displacement is generally carried out at temperatures of 150 to 400 ° C, preferably 200 to 360 ° C, particularly preferably 260 to 340 ° C. The pressure is generally from 4 to 150 bar, preferably 20 to 120 bar, particularly preferably 70 to 100 bar. The release step is carried out with residence times of generally 0.01 to 5 s, preferably 0.1 to 2 s, particularly preferably 0.1 to 0.5 s.

Following the displacement, the reaction mixture is immediately cooled by 20 to 200 ° C., preferably by 50 to 150 ° C., below the reaction temperature.

The desired C ₄ - to C ₀ -α-olefin is then isolated from the reaction mixture obtained by processes known to those skilled in the art. The trialkylaluminum compound obtained in step c), preferably the trialkylaluminum compound (A), which is obtained in step c) when the olefins released in step a) are used, can be recycled in step a) of the process according to the invention.

Another object of the present application is a process for the preparation of trialkylaluminum compounds (B), containing at least one alkyl group derived from a C ₄ - to C ₃₀ -α-olefin, by reacting a C - C ₃ o-olefin with an internal double bond or a mixture of C - to C ₃₀ -olefins with internal double bonds with a trialkylaluminum compound (A) in the presence of a heterogeneous catalyst for isomerizing transalkylation to form a C ₄ - to C ₃₀ -α-olefin or a mixture of C ₄ - to C ₃₀ -α-olefins, which displaces the corresponding alkyl radicals from the trialkylaluminum compound (A), which are released as the olefins corresponding to the alkyl groups, and attaches to the aluminum with the formation of corresponding trialkylaluminum compounds (B).

Preferred olefins with internal double bonds, trialkylaluminum compounds (A) and heterogeneous catalysts for isomerizing transalkylation are the same as those already mentioned above with regard to step a) of the process according to the invention for the preparation of C ₄ - to C ₃₀ -α-olefins. The reaction conditions are also preferably the same as those mentioned with regard to step a) of the process according to the invention for the production of C - to C ₃₀ -α-olefins. The trialkylaluminum compounds (B) prepared in the presence of a heterogeneous catalyst for isomerizing transalkylation can be reacted with an olefin with the liberation of C ₄ - to C ₃₀ -α-olefins. This reaction can be carried out thermally, in the absence of catalysts, as disclosed in step c) of the process according to the invention for the preparation of C ₄ - to C ₃ o-α-olefins, the reaction mixture obtained from the catalyst used for the isomerizing transalkylation is separated beforehand (see step b) of the process according to the invention for the preparation of C ₄ - to C ₃₀ -α-olefins). It is also possible to carry out the release (displacement) of the desired C ₄ - to C ₃₀ -α-olefins from the trialkylaluminum compounds (B) prepared in the presence of a heterogeneous catalyst for the isomerizing transalkylation with the aid of a catalyst for the transalkylation. The catalyst used is either a catalyst that is little isomerized, e.g. a catalyst containing cobalt, molybdenum, iron, rhodium or iridium, or - since the isomerization is slower than the transalkylation - a catalyst that was already used in the isomerizing transalkylation, whereby the contact time during the displacement is short in this case. The catalyst used in the previous step (isomerizing transalkylation), for example a nickel catalyst, can thus be used as the catalyst. In principle, however, it is also possible to use a catalyst for transalkylation that is different from the catalyst for the isomerizing transalkylation.

If the displacement is carried out in the presence of a catalyst, it is generally carried out at temperatures of 10 to 80 ° C. Olefins suitable for catalytic displacement correspond to olefins suitable for thermal displacement and have already been mentioned above.

The olefins used in the displacement are generally used in a stoichiometric excess in relation to the alkyl groups to be released as desired C ₄ to C ₃ o-α-olefins in the trialkylaluminum compound (B). An at least 100 mol% excess is preferably used, particularly preferably an at least 300 mol% excess. This shifts the equilibrium of the displacement to the side of substitution with the olefins used in the displacement, the desired C ₄ to C ₃₀ α-olefins being released. The present application further relates to the use of a heterogeneous catalyst for isomerizing transalkylation, preferred heterogeneous catalysts for isomerizing transalkylation having already been mentioned above, in a process for the preparation of C ₄ - to C ₃₀ -α-olefins by isomerization of C ₄ - to C ₃ o-olefins with internal double bonds. Preferred olefins used and produced are also mentioned above.

Claims

claims

1. A process for producing C ₄ to C ₃₀ α-olefins from C ₄ to C ₃₀ olefins having internal double bonds, comprising the following

Steps:

a) reaction of a C ₄ -C ₃₀ -olefin with internal double bond or a mixture of C ~ to C ₃₀ -olefins with internal double bonds with a trialkylaluminum compound (A) in the presence of a catalyst for isomerizing transalkylation to form a C ₄ - to C ₃ o-α-olefins or a mixture of C - to C ₃ o-α-olefins which displaces the corresponding alkyl radicals from the trialkylaluminum compound (A), which are released as the olefins corresponding to the alkyl groups, the C - bis C ₃₀ -α-olefin attaches to the aluminum to form a corresponding trialkylaluminum compound (B), wherein at least one of the alkyl groups bonded to the aluminum is an alkyl group derived from the C ₄ - to C ₃₀ -α-olefin, and

wherein the reaction in step c) takes place thermally, in the absence of catalysts.

2. The method according to claim 1, characterized in that C ₄ - to C ₁₄ -α- olefins, preferably C ₆ -C ₁₀ -α-olefins are prepared.

3. The method according to claim 1 or 2, characterized in that the catalyst for isomerizing transalkylation is a heterogeneous catalyst.

4. The method according to claim 3, characterized in that the heterogeneous catalyst contains nickel.

5. The method according to any one of claims 1 to 4, characterized in that the trialkyl aluminum compound (A) is selected from the group consisting of trineohexyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum, triethyl aluminum and tri-n-propyl aluminum.

6. The method according to any one of claims 1 to 5, characterized in that the olefin released in step a) from the trialkylaluminum compound (A) is continuously removed from the reaction mixture.

7. The method according to any one of claims 1 to 6, characterized in that the thermal release in step c) takes place at a temperature of 260 to 340 ° C.

8. The method according to any one of claims 1 to 7, characterized in that the thermal release in step c) takes place at a pressure of 20 to 120 bar.

9. Process for the preparation of trialkylaluminum compounds (B) containing at least one alkyl group derived from a C ₄ -C ₃₀ -α-olefin, by reacting a C ₄ -C ₃₀ -olefin with an internal double bond or a mixture of C ₄ to C ₃₀ olefins with internal double bonds with a trialkyl aluminum compound

(A) in the presence of a heterogeneous catalyst for isomerizing transalkylation to form a C ₄ - to C ₃ o-α-olefin or a mixture of C ₄ - to C ₃₀ -α-olefins, which from the trialkylaluminum compound (A) the corresponding alkyl radicals displaced, which are released as olefins corresponding to the alkyl groups, and attaches to the aluminum with the formation of corresponding trialkylaluminum compounds (B).

10. The method according to claim 9, characterized in that the active metal component of the heterogeneous catalyst is selected from the group consisting of cobalt, chromium, nickel, iron, rhodium, iridium and molybdenum or mixtures thereof.

11. A process for the preparation of C ₄ to C ₃₀ α-olefins from C ₄ to C ₃₀ olefins having internal double bonds, comprising the following steps:

a) preparation of a trialkyl aluminum compound by a process according to one of claims 9 or 10,

b) optionally removing the heterogeneous isomerization catalyst, and

c) reaction of the trialkylaluminum compound (B) formed in step a) with an olefin with displacement of the desired C - to C ₃ o-α-olefin,

the displacement can take place thermally or catalytically.

12. Use of a heterogeneous catalyst as a catalyst for isomerizing transalkylation in the isomerizing transalkylation according to step a) of the process according to one of claims 1 to 8 and 11.

13. Use according to claim 12, characterized in that the active metal component of the heterogeneous catalyst is selected from the group consisting of cobalt, chromium, nickel, iron, rhodium, iridium and molybdenum or mixtures thereof.