WO1996023751A1

WO1996023751A1 - Process for preparing olefin oligomers

Info

Publication number: WO1996023751A1
Application number: PCT/EP1996/000235
Authority: WO
Inventors: Joachim Rösch; Hans-Joachim Müller; Günther SCHWEIER; Peter Tanzmeier
Original assignee: Basf Aktiengesellschaft
Priority date: 1995-02-01
Filing date: 1996-01-20
Publication date: 1996-08-08
Also published as: EP0807096A1

Abstract

A process is disclosed for preparing olefin oligomers with a molecular weight distribution Mw/Mn in a range from 1.0 to 2.4 by oligomerisation of olefins in the presence of metallocene catalyst systems. The turbidity index of the catalyst-containing reaction mixture lies in a range from 1 to 10. The olefin oligomers are useful as starting materials for preparing lubricants, fuel and oil additives, and as macromonomers.

Description

Process for the preparation of olefin oligomers

description

The present invention relates to an improved process for the preparation of olefin oligomers with a molecular weight distribution Mw / Mn in the range from 1.0 to 2.4 by oligomerization of olefins in the presence of metallocene catalyst systems.

The invention further relates to olefin oligomers obtainable by a process according to claims 1 to 4, and to the use of the olefin oligomers for the production of lubricants or fuel additives.

Olefin oligomers are valuable starting products for the production of fuel and oil additives, lubricants and plasticizers. They can also be used as macromonomers.

It is generally advantageous if the modified products obtainable from the olefin oligomers, such as, for example, lubricants or fuel additives, have a narrow, monomodal molecular weight distribution. If, on the other hand, the molecular weight distribution is relatively broad, the relatively high molecular weight oligomer fractions can have an adverse effect on the shear stability or valve cleaning characteristics.

It is therefore generally advantageous if the starting materials themselves, ie the olefin oligomers, already have a narrow molecular weight distribution Mw / Mn.

EP-A 0 268 214 describes the oligomerization of propylene with five-fold alkyl-substituted cyclopentadienyl complexes (metallocene complexes) without the molecular weight distribution Mw / Mn of the propylene oligomers being disclosed.

EP-A 0 596 553 describes olefin oligomerizations with metallocene catalysts, the cyclopentadienyl ligands of which are substituted by different alkyls. Here, too, the molecular weight distribution Mw / Mn of the oligomers is not mentioned.

The metallocene complexes described are difficult to prepare, their productivity and their solubility in the monomer leave something to be desired. EP-A 0 540 108 describes the preparation of olefin oligomers having a molecular weight distribution of 1.1 to 5.0. However, very special preparative, complex metallocene complexes are also used as catalyst components, the productivity and solubility of which leave something to be desired.

It was therefore an object of the present invention to provide an improved process for the preparation of olefin oligomers from olefins whose molecular weight distribution is in the range from 1.0 to 2.4 and which is easily accessible with high productivity using soluble catalyst systems can be manufactured.

Accordingly, a process for the preparation of olefin oligomers with a molecular weight distribution Mw / Mn in the range from 1.0 to 2.4 by oligomerization of olefins in the presence of metallocene catalyst systems was found, the turbidity number of the catalyst-containing reaction mixture in the range from 1 to 10 lies.

In addition, the olefin-oligomer mixtures obtainable by the process according to claims 1 to 4 were found, and the use of the olefin-oligomers for the production of lubricants or fuel additives.

The olefins are linear and ring-shaped with 2 to 12 carbon atoms, for example α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 4-methylpentene-1 or vinylcyclohexane are suitable, and also olefins with an internal double bond such as E- and Z-2-butene, E- and Z-2-pentene, E- and Z- 3-witches. Cyclopropanes, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclonones, cyclodecene and norbornene are suitable as cycloolefins. C ₂ - to C -α-01efins, such as ethylene, propene, 1-butene and in particular propene, are preferably used.

In addition to the pure olefins, it is of course also possible to oligomerize mixtures of different olefins having 2 to 12 carbon atoms. The molar ratio of the individual olefin components to one another is generally not critical if one observes that the amount of ethylene units in the cooligomers is generally 0.01 to 5 mol%, preferably 0.01 to 3 mol%, in total is particularly 0.01 to 2 mol%.

No particular requirements are imposed on the catalyst systems of the process according to the invention, except that they are largely soluble in the reaction mixture. The reaction mixture is the mixture which is present in the time after all reaction components have been combined until the catalyst system has been destroyed after the oligomerization reaction has taken place. The solubility of the catalyst system in the reaction mixture is determined by measuring the turbidity of the reaction mixture analogously to DIN 38404. The catalyst system is largely soluble in the sense of the invention if the turbidity number is in the range from 1 to 10, preferably in the range from 1 to 3.

The metallocene component of the catalyst system is a so-called titanocene-zirconocene and hafnocene derivative, hence complexes of titanium, zirconium and hafnium, in which the metal atom M is bonded between two optionally substituted cyclopentadienyl groups, the remaining valences of Central atom M are saturated by easily exchangeable leaving atoms or leaving groups X ¹ , X ² .

Suitable metallocene complexes are those with the general formula Cp ₂ MX ^x X ² in which M is titanium, zirconium or hafnium, preferably zirconium.

Cp represent a pair of optionally substituted cyclopentadienyl ligands.

In the event that the substituents are C ₅ to C ₃ o-alkyl groups, the cyclopentadienyl rings are substituted symmetrically. This means that the type, number and also the position of the alkyl substituents of the one Cp ring is identical to the type, number and also position of the alkyl substituents of the second Cp ring. The number of alkyl groups per cyclopentadienyl ring is 1 to 4.

Suitable C5 to C3c alkyl radicals for the purposes of the invention are the aliphatic pentyl, hexyl, heptyl, octyl, nonyl, decyl,

Undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl and their isomers, such as neo-pentyl, iso-octyl, and the cycloaliphatic cyclopentyl, cyclohexyl.

N-Octadecyl is particularly suitable.

The optionally C ₅ - to C ₃ o-alkyl-substituted cyclopentadienyl units can also be substituted by 1 to 2 C - to Cio-alkylene units, which together with the cyclopen- tadienyl unit form a fused ring system, such as the tetrahydroindenyl system.

However, substituted cyclopentadienyl ligands are also possible in pairs in which at least one cyclopentadienyl unit is substituted with at least one organosilyl group -Si (R ¹ ) ₃ . R ¹ then denotes a Ci to C ₃ o-carbon organic group such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec.-butyl, tert.-butyl, n -Pentyl, i-pentyl, neo-pentyl, hexyl, heptyl, octyl, nonyl, cyclohexyl, phenyl, p-tolyl. Preferred organosilyl radicals are trimethylsilyl and tert-butyldimethylsilyl, in particular trimethylsilyl.

In the case of organosilyl substitution on the cyclopentadienyl units, the symmetrical substitution pattern is not absolutely necessary, but is also not excluded.

Easily exchangeable, formally negatively charged leaving atoms or leaving groups X ¹ , X ^{2 of} the metallocene complexes of the general formula I are: hydrogen, halogen such as fluorine, bromine, iodine and preferably chlorine.

In addition, alcoholates such as methanolate, ethanolate, n- and i-propanolate, phenolate, trifluoromethylphenolate, naphtholate, silanolate may be mentioned.

Furthermore, particularly recommended for X ¹ , X ^{2 are} aliphatic Ci to Cio-alkyl radicals, in particular methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neo -Pentyl, hexyl, preferably methyl, tert-butyl and neo-pentyl. Furthermore, alicyclic C ₃ to C ₂ hydrocarbon radicals, such as cyclopropyl, cyclobutyl, cyclopentyl and in particular cyclohexyl or C ₅ to C ₂ o-bicycloalkyl, such as bicyclopentyl, and in particular bicycloheptyl and bicyclooctyl.

Examples of substituents X ¹ , X ² with aromatic structural units are Cβ- to cis-aryl, preferably phenyl, or naphthyl, alkyl aryl or arylalkyl, each having 1 to 10 C atoms in the alkyl radical and 6 to 20 C atoms in the aryl radical such as tolyl, benzyl.

Examples of suitable metallocene complexes I are: bis (n-oetadecylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopentadienyl) zirconium dichloride, bis (tetrahydroindenyl) zirconium dichloride, bis [(tert.-butyldimethylsilydichlorodichlorodichloride) dichloride -butylcyclopentadienyl) zirconium dichloride. The metallocene complexes of the general formula I can be synthesized in a simple manner by known processes, for example Brauer (ed.): Handbuch der preparative inorganic chemistry, volume 2, 3rd editions, pages 1395 to 1397, Enke, Stuttgart 1978. A preferred process is based on the lithium salts of the appropriately substituted cyclopentadienyls, which are reacted with the transition metal halides.

Only one metallocene complex is expediently used in the oligomerization reaction, but it is also possible to use mixtures of different metallocene complexes.

In addition to the metallocene complexes A), the catalyst systems according to the invention also contain activators B) which are known per se and are also called cocatalysts in the literature. In general, they alkylate the transition metal component A) of the catalyst system and / or abstract a ligand X from the transition metal component, so that a catalyst system for the oligomerization of olefinically unsaturated hydrocarbons can ultimately result. Organometallic compounds of the 1st to 3rd main group or the 2nd subgroup of the periodic table are generally suitable for this task, but other acceptor compounds such as, for example, carbocation salts can also be used.

Particularly suitable activator compounds are aluminum organyl, boron organyle and carbocation salts. Open-chain or cyclic alumoxane compounds of the general formula II or III are preferred, which can be obtained according to US Pat. No. 4,794,096 by reacting aluminum trialkyls with water.

R

AI- 4-0 —AI -4- m II

-f- O AI - III m

Herein, R represents a Ci to C _ß alkyl group, preferably Methyl¬ or ethyl group, and m is an integer from 5 to 30, preferably 10 to 25th As a rule, the oligomeric alumoxane compounds are present as mixtures of both linear and cyclic chain molecules of different lengths, so that m is to be regarded as the mean.

Also suitable as cocatalysts are generally aluminum organyls of the general formula Al (R ² ) ₃ , where R ^{2 is} hydrogen, C 1 - to C 10 -alkyl, preferably C 1 to C ₄ -alkyl, in particular methyl, ethyl, butyl. In addition, R ^{2 can} also represent arylalkyl or alkylaryl, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical.

aluminum alkyls A1 (R ² ) ₃ are furthermore suitable in which R ² can mean fluorine, chlorine, bromine or iodine in addition to the radicals defined above, with the proviso that at least one radical R ^{2 is} a C-organic radical or is a hydrogen atom. Particularly preferred compounds are trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, di-isobutyl aluminum hydride, diethyl aluminum chloride.

In addition, organic boron compounds are also very suitable as activators, for example tris-arylboron compounds, preferably tris (pentafluorophenyl) boron, furthermore salts of carbonium ions, preferably triphenylmethyl tetraaryl borate, in particular triphenylmethyl tetra (pentafluoropheny dborate).

The Al, B or C compounds mentioned are known or can be obtained in a manner known per se.

The activators can be used alone or as mixtures in the catalyst system.

The activator component B) is preferably used in a molar excess with respect to the metal complex A).

The molar ratio of activator B) to metal complex A) is generally 100: 1 to 10000: 1, preferably 100: 1 to 1000: 1.

The constituents of the catalyst systems according to the invention can be introduced into the oligomerization reactor individually or as a mixture in any order; the metallocene complex is preferably mixed with at least one activator component before it enters the reactor, that is to say preactivated. A particular advantage of the catalyst systems of the process according to the invention is their substantial solubility in the reaction mixture.

The oligomers according to the invention can be prepared in the conventional reactors used for the oligomerization of olefins, either batchwise or preferably continuously. Suitable reactors include Konuierlich operated stirred kettle, where it is also possible to use a number of several stirred kettles connected in series.

The oligomerization can be carried out in the gas phase, in a suspension, in liquid monomers and in inert solvents. In the case of oligomerization in solvents, in particular liquid hydrocarbons such as benzene, ethylbenzene or toluene are used. The oligomerizations are preferably carried out in a reaction mixture in which the liquid monomer is present in excess, preferably more than 60% by volume absolute and in particular more than 80% by volume absolute.

In a preferred process according to the invention for the preparation of the olefin oligomers, the oligomeric aluminoxane compound, preferably as a solution in toluene, is initially introduced. For this purpose, for example, the olefin with 2 to 12 carbon atoms is added and the temperature is increased. After addition of the metallocene complex, oligomerization is carried out for 20 to 800 minutes, preferably 50 to 200 minutes. The temperatures here are from 0 to 250 ° C., preferably from 20 to 200 ° C., and the work is carried out at pressures from 100 to 300,000 kPa, preferably in the range from 100 to 10,000 kPa and in particular in the range from 100 to 4000 kPa.

The oligomerization can therefore be carried out using the low-pressure, medium-pressure and high-pressure processes. The amount of catalyst used is not critical.

This gives oligomers with molecular weights Mw (weight average) of preferably 100 to 20,000, particularly preferably 100 to 10,000, in particular 100 to 5,000, which have a high content of terminal vinylidene double bonds.

The degree of polymerization of the olefin oligomers is generally in the range from 2 to 200, preferably in the range from 2 to 100. The molecular weight distribution Mw / Mn (weight average / number average), measured with the method of gel permeation chromatography (GPC) at 35 ° C. with polystyrene as column material and THF as solvent against a polystyrene standard, the 5 olefin oligomers thus obtained is 1. 0 to 2.4, preferably 1.8 to 2.2 and in particular 1.8 to 2.0.

The GPC diagram advantageously shows only a relative maximum for the molecular weight distribution, i.e. there is a monomodal molecular weight distribution.

The olefin oligomers obtained in this way can be further processed with the customary chemical reactions, such as hydoformylation or hydroamination or a combination of both methods, to functionalized oligo-olefins which are suitable, for example, as lubricants or fuel or oil additives are. Because of their double bond content, the olefin oligomers obtained can also be used as macromonomers.

0 examples

Manufacture of olefin oligomers

Example 1 5

16 ml of a 1.7 molar methylalumoxane solution in toluene were placed in a 1 l stirred autoclave, 500 g (11.9 mol) of liquid propene were condensed and heated to 50.degree. A pressure of 2200 kPa was set. Then 79.6 mg (0.1 mmol)

30 bis (n-octadecylcyclopentadienyl) zirconium dichloride, dissolved in 9.4 ml of 1.7 molar toluene methylaluminoxane solution (AI: Zr = 432: 1), were added. The mixture was then oligomerized for 120 minutes, the reactor was depressurized and the turbidity number was determined. It was 1.8. 450 g of liquid propene oligomer mixture were isolated: Mw =

35,990, Mn = 520, Mw / Mn = 1.9.

Example 2

The procedure was as in Example 1, but instead of 40 bis (n-octadecylcyclopentadienyl) zirconium dichloride 25.0 mg (0.05 mmol) of bis (tert-butyldimethylsilyl) cyclopentadienyl] zirconium dichloride was dissolved in 14.7 ml 1.7 molar toluene methyl aluminoxane solution (Al: Zr = 1040: 1) used as a metallocene complex. 450 g of liquid propylene oligomer mixture were obtained. 45 Mw = 3600, Mn = 1800, Mw / Mn = 2.0. Turbidity number of the reaction mixture 2.1. Example 3

90 ml of a 1.7 m toluene methylaluminoxane solution (153 mmol) and then 240 mg (0.3 mmol) of bis (n-octadecylcyclopentadienyl) zirconium dichloride (Al: Zr = 510: 1), oligomerized 10, were added to 204 g of cyclopentene h at 30 ° C and determined the turbidity number. 30 g of cyclopentene oligomers were obtained, Mw = 700, Mn = 350; Mw / Mn = 2.0. Turbidity number of the reaction mixture 1.8.

Example 4

The procedure was as in Example 1, but 40 mg (0.1 mmol) of bis (tetrahydroindenyl) zirconium dichloride were dissolved in 4.5 ml of 1.7 M toluene methylaluminoxane solution (Al: Zr = 348: 1). 450 g of liquid propylene oligomer were obtained, Mw = 3600, Mn = 1800, Mw / Mn = 2.0. Turbidity number of the reaction mixture 2.7.

Comparative Example VI

The procedure was as in Example 1, but instead of bis (n-octadecylcyclopentadienyl) zirconium dichloride 29.0 mg (0.1 mmol) of bis (cyclopentadienyl) zirconium dichloride was dissolved in 9.4 ml of 1.7 molar toluene methylaluminoxane solution (AI: Zr = 500: 1) used as a metallocene complex. 440 g of liquid propylene oligomer mixture were obtained. Mw = 1550, Mn = 420, Mw / Mn = 3.7. Turbidity number of the reaction mixture 85.

Claims

1. A process for the preparation of olefin oligomers with a molecular weight distribution Mw / Mn in the range from 1.0 to 2.4 by oligomerization of olefins in the presence of metallocene catalyst systems, characterized in that the turbidity number of the catalyst-containing reaction mixture is in the range from 1 to 10 .

2. The method according to claim 1, characterized in that catalyst systems are used, which as active ingredients

A) Metallocene complexes of the general formula I

Cp ₂ Mχ ^! χ ² I

in which the substituents and indices have the following meaning:

Cp ₂

A pair of substituted cyclopentadienyl ligands as defined:

(i) symmetrical substitution with 1 to 4 C ₅ - bis each

C ₃ 0- alkyl radicals, or

(ii) Substitution with 1 to 2 ring-forming C ₄ to C ₁₀ alkylene radicals and 0 to 3 Ci to C ₃ o-alkyl radicals each, or

(iii) Substitution of at least a part of the ligand pair with at least one silicon-organic radical and 0 to 9 Ci to C ₃ o-alkyl radicals and / or 0 to 4 ring-forming C ₄ to Cχo alkylene radicals.

M is a titanium, zirconium or hafnium atom X ¹ , X ^{2 is} a formally negatively charged leaving atom or a formally negatively charged leaving group

and B) an acceptor compound for the substituents X ¹ and X ² of component A) as an activator

contain.

Process according to Claims 1 to 2, characterized in that the catalyst systems contain open-chain or cyclic aluminoxane compounds of the general formula II or III as activators

AI- 4-o AI R m II

-o —A1 - III m

R

where R is a Ci to Cβ alkyl group and m is an integer from 5 to 30.

4. The method according to claims 1 to 3, characterized gekennzeich¬ net that the substituents X ¹ , X ^{2 is} halogen, H, C ~ ~ to Cio-alkyl or Ci- to Cio-alkoxy.

5. olefin oligomers obtainable by a process according to claims 1 to 4.

6. Use of the olefin oligomers for the production of lubricants or fuel additives.