WO2015148496A1

WO2015148496A1 - PROCESS FOR MANUFACTURING LINEAR α-OLEFINS

Info

Publication number: WO2015148496A1
Application number: PCT/US2015/022232
Authority: WO
Inventors: Joel Citron
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2014-03-26
Filing date: 2015-03-24
Publication date: 2015-10-01

Abstract

In a process for producing linear α-olefins by the catalyzed oligomerization of ethylene, the product distribution can be tailored to meet market demands by using two different catalysts the both give a Schulz-Flory distribution of products. These two catalysts have different Schulz-Flory constants. Variations of these Schulz-Flory constants and the molar ratio of the two catalysts in the process can be used to tailor the product distribution.

Description

PROCESS FOR MANUFACTURING LINEAR a-OLEFINS

FIELD OF THE INVENTION

The relative proportions of linear a-olefins produced by an ethylene

oligomerization catalysts which give a Schulz-Flory distribution of the olefin products can be modified by using at least two different oligomerization catalysts, each having a different Schulz-Flory constant.

TECHNICAL BACKGROUND

Linear a-olefins (LAOs) are important items of commerce, large quantities being made for use as monomers for polymerization and for use as chemical intermediates. Most LAOs are made by the oligomerization of ethylene. The catalysts for this oligomerization fall into two categories, those that make specific LAOs such as 1-hexene or 1-octene, and those that make a series of LAOs such as 1-butene, 1 -hexene,

1-octene, 1-decene, 1 -dodecene, etc. Generally speaking those catalysts that make a series of LAOs, produce the individual LAOs in relative amounts that follow a distribution function, usually a Poisson distribution or a Schulz-Flory distribution. The amounts of LAOs produced in a Poisson distribution can be changed by changing the molar ratios of the materials used in the process, but in a Schultz-Flory distribution generally these ratios are dependent on the catalyst system used, and sometimes also to at least some extent on the process conditions.

The desirability of producing individual LAOs depends on demand for them in the marketplace, and this has varied with time, see W. Keim, Angew. Chem. Int. Ed., vol. 52, p. 12492-12496 (2013), and US Patent 6,501 ,000, both of which are hereby included by reference. At the time LAOs were first produced in large quantities, in the early 1970's, the main use was as intermediates for soaps surfactants and detergents, and the LAOs in most demand had 12 to 18 carbon atoms. Starting about 1990 demand increased for LAOs having 4, 6, 8 and 10 carbons atoms for used a monomers in polyolefin production. Recently it is believed that demand for LAOs having more than 18 carbon atoms, say up to 30 or 40 carbon atoms, has increased, perhaps due their use as intermediates in the production of additives for fracking fluids for extracting oil and natural gas. Thus the spectrum of LAOs that are in demand in the marketplace has expanded over time. Therefore, a process for producing LAOs using an oligomerization catalyst system which produces a series of LAOs with a Schulz-Flory distribution and in which the distribution could be varied to produce LAOs which are in demand is desired.

World Patent Application 201 1/126784 describes a process in which a catalyst for oligomerizing ethylene to a-olefins and an ethylene polymerization catalyst are used together to produce a branched polyethylene. A second ethylene oligomerization catalyst optionally be present.

SUMMARY OF THE INVENTION

This invention concerns, a process for the production of linear a-olefins, comprising, oligomerizing ethylene to form said linear α-olefins using, a first

oligomerization catalyst that forms said linear α-olefins in proportions that is a Schulz- Flory distribution, and a second oligomerization catalyst that forms said linear α-olefins in proportions that is a Schulz-Flory distribution, and provided that said first oligomerization catalyst has a Schulz-Flory constant that is greater than a Schulz-Flory constant for said second oligomerization catalyst, said Schulz-Flory constant being measured under process conditions.

DETAILED DESCRIPTION

Herein certain terms are used, and they are defined below.

By a LAO is meant a compound of the formula H2C=CH(CH₂CH2)_nH, wherein n is an integer of one or more. There is no upper limit on n but in practical terms (that is it can be detected) it will usually not exceed 200 in any significant quantity in most product mixes.

By an "oligomerization catalyst" is not meant just the entity or compound which actually forms the LAOs produced but also any other compounds such as activators or cocatalysts which may be needed to form and/or maintain an active catalyst system.

By "hydrocarbyl group" is meant a univalent group containing only carbon and hydrogen. As examples of hydrocarbyls may be mentioned unsubstituted alkyls, cycloalkyls, and aryls. If not otherwise stated, it is preferred that hydrocarbyl groups (and alkyl groups) herein contain 1 to about 30 carbon atoms.

By "substituted hydrocarbyl" is meant a hydrocarbyl group that contains one or more substituent groups that are inert under the process conditions to which the compound containing these groups is subjected (e.g., an inert functional group, see below). The substituent groups also do not substantially detrimentally interfere with the polymerization process or the operation of the polymerization catalyst system. If not otherwise stated, it is preferred that (substituted) hydrocarbyl groups herein contain from 1 to about 30 carbon atoms. Included in the meaning of "substituted" are rings containing one or more heteroatoms, such as nitrogen, oxygen, and/or sulfur, and the free valence of the substituted hydrocarbyl may be to the heteroatom. In a substituted hydrocarbyl, all of the hydrogens may be substituted, as in trifluoromethyl.

By "(inert) functional group" herein is meant a group, other than hydrocarbyl or substituted hydrocarbyl, that is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially deleteriously interfere with any process described herein where the compound in which they are present takes part. Examples of functional groups include halo (fluoro, chloro, bromo and iodo), and ether such as -OR⁵⁰ wherein R⁵⁰ is hydrocarbyl or substituted hydrocarbyl. In cases in which the functional group may be near a transition metal atom, the functional group alone should not coordinate to the metal atom more strongly than the groups in those compounds that are shown as coordinating to the metal atom, that is, they should not displace the desired coordinating group.

By a "cocatalyst" or a "catalyst activator" is meant one or more compounds that react with a transition metal compound to form an activated catalyst species. One such catalyst activator is an "alkylaluminum compound," which herein means a compound in which at least one alkyl group is bound to an aluminum atom. Other groups, such as, for example, alkoxide, hydride, an oxygen atom bridging two aluminum atoms, and halogen may also be bound to aluminum atoms in the compound.

By a "series" of a-olefins is meant compounds having the formula

H(CH2CH2)nCH=CH₂ wherein at least three compounds, more preferably at least 5 compounds, having different q values are produced. Preferably at least three of these values are 1 , 2, and 3.

By "aryl" is meant a monovalent aromatic group in which the free valence is to the carbon atom of an aromatic ring. An aryl may have one or more aromatic rings, which rings may be fused, connected by single bonds, or connected to other groups.

By "substituted aryl" is meant a monovalent substituted aromatic group that contains one or more substituent groups that are inert under the process conditions to which the compound containing these groups is subjected (e.g., an inert functional group, see below). The substituent groups also do not substantially detrimentally interfere with the polymerization process or operation of the polymerization catalyst system. If not otherwise stated, it is preferred that (substituted) aryl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of "substituted" are rings containing one or more heteroatoms, such as nitrogen, oxygen, and/or sulfur, and wherein the free valence of the substituted hydrocarbyl may be to the heteroatom. In a substituted aryl, all of the hydrogens may be substituted, as in trifluoromethyl. These substituents include (inert) functional groups. Similar to an aryl, a substituted aryl may have one or more aromatic rings, which rings may be fused, or connected by single bonds or connected to other groups; however, when the substituted aryl has a heteroaromatic ring, the free valence in the substituted aryl group can be to a

heteroatom (such as nitrogen) of the heteroaromatic ring instead of a carbon.

The Schulz-Flory equation describes a specific distribution of products obtained in some chemical processes, and is well known in the art. In the present process, the "Schulz-Flory constant" or "SFC" of the mixtures of a-olefins produced is a measure of the relative amounts of the olefins obtained, usually denoted as factor K (sometimes also called "a"), from the Schulz-Flory theory (see for instance B. Elvers, et al., Ed. Ullmann's Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH,

Weinheim, 1989, pp. 243-247 and 275-276, which is hereby included by reference. This is defined as:

K = (C_n+2 olefin)/(Cn olefin)

wherein (C_n olefin) is the number of moles of olefin containing n carbon atoms, and (Cn+2 olefin) is the number of moles of olefin containing n+2 carbon atoms, or in other words the next higher oligomer of C_n olefin. From this can be determined the weight (mass) and/or mole fractions of the various olefins in the resulting oligomeric reaction product mixture.

Generally speaking the SFC can be determined by analyzing the resulting product stream for the relative amounts of a-olefins present and doing the calculation of the K for each olefin pair, such as 1-hexene and 1-octene, 1-octene and 1 -decene, etc. The individual values obtained for each pair are then usually averaged to get the overall SFC. Theoretically this average value should be the same for each measured individual par, but due to experimental error they may vary somewhat. This error may be particularly acute for volatile olefins such as 1 -butene and 1-hexene which are easily lost during handling and sampling of the product stream. The relative amounts of the α-olefins present may be measured by several methods. For example for relatively volatile (lower molecular weight) oolefins they may be measured by gas

chromatography, and for relatively nonvolatile (higher molecular weight) oolefins by liquid chromatography, both methods calibrated by using appropriate standards. Herein distributions that show small deviations from a theoretical or "perfect" distribution will still be considered to be Schulz-Flory distributions.

It should be noted that in the present process as the molecular weight of the olefin produced is higher, there are more chances for side products to be formed, such as internal olefin and/or branched olefin. Particularly if these side products represent a substantial portion of any of the materials having a certain number of carbon atoms, these side products should be included in the calculation of the SFC for any product fraction having a particular number of carbon atoms. The product of the present process consists essentially of a homologous series of LAOs. Included in the term "consisting essentially of" are the side products of the process as mentioned in this paragraph.

Table 1 shows the weight percentages of each LAO produced by a particular catalyst. Column 1 is the number of ethylene units contained in each LAO, To get the number of carbon atoms in each LAO multiply by 2. Columns 3 and 6 are used to calculate the molar ratios of each LAO produced, column 3 for a catalyst having a SFC of 0.6 and col. 6 for an catalyst with an SFC of 0.85. Columns 4 and 7 give the weights of each LAO produced for SFCs of 0.60 and 0.85 respectively. Finally columns 5 and 9 give the weight percents of each LAO produced with catalysts having SFCs of 0.60 and 0.85, respectively. As can be seen, a catalyst with a SFC of 0.60 produces LAOs mostly in the range of 4 to 16 carbon atoms, useful for monomers and as intermediates for soaps and detergents. However it does produce not as much LAO having more than 16 carbon atoms which have recently become more in demand. On the other hand the catalyst with an SFC of 0.85 does not produce as LAO having 6 to 10 carbon atoms, which are valuable as monomers for polymerization.

In this instance a mixture of the two catalysts, in the correct proportion to produce the same weight amount of 1-butene, produces a more "balanced" mixture of LAOs that may better meet market demands, see column 9 for weight percents produced by the two catalysts combined. If we assume each of the oligomerization catalysts produce the same weight of total LAOs per unit time, then the catalyst having an SFC of 0.60 will be about 15 mole percent of the total oligomerization catalyst present, and the catalyst having an SFC of 0.85 will be about 85 mole percent of the total oligomerization catalyst present. This assumption can be readily checked by performing the process with these two oligomerization catalysts. After the result is obtained this molar ratio can be adjusted to change the relative amounts of higher and lower molecular weight LAOs. For instance if it is desired to increase the relative amount of lower molecular weight LAOs a higher proportion of the catalyst with the lower SFC (0.60 in this instance) can be used

Thus depending on market demand the output of the LAO process may be adjusted simply by adjusting the relative proportions of the oligomerization catalyst, and the SFCs of the catalysts themselves. Similar calculations using various proportions of the two oligomerizations catalysts and various SFCs for the catalysts can be made to optimize the mixture of LAOs produced.

Table 1

36 1008 0.00 0.00 0.00 0.00 4.02 0.28 0.24

37 1036 0.00 0.00 0.00 0.00 3.51 0.25 0.21

38 1064 0.00 0.00 0.00 0.00 3.06 0.21 0.18

39 1092 0.00 0.00 0.00 0.00 2.67 0.19 0.16

40 1120 0.00 0.00 0.00 0.00 2.33 0.16 0.14

41 1148 0.00 0.00 0.00 0.00 2.03 0.14 0.12

42 1176 0.00 0.00 0.00 0.00 1.77 0.12 0.11

43 1204 0.00 0.00 0.00 0.00 1.54 0.11 0.09

44 1232 0.00 0.00 0.00 0.00 1.34 0.09 0.08

45 1260 0.00 0.00 0.00 0.00 1.16 0.08 0.07

46 1288 0.00 0.00 0.00 0.00 1.01 0.07 0.06

47 1316 0.00 0.00 0.00 0.00 0.88 0.06 0.05

48 1344 0.00 0.00 0.00 0.00 0.76 0.05 0.05

49 1372 0.00 0.00 0.00 0.00 0.66 0.05 0.04

50 1400 0.00 0.00 0.00 0.00 0.57 0.04 0.03

By definition, an SFC must be 0.00 to 1.00. If it is 0.00 only a dimer (in this instance 1 -butene) is produced while if it is 1.00 only (in theory) a polymer having an infinite molecular weight is produced. Thus it is preferred that the first oligomerization catalyst have a SFC of 0.98 or less, preferably about 0.95 or less and very preferably about 0.90 or less. It is also preferred that the second oligomerization catalyst have a SFC of about 0.25 or more, preferably about 0.30 or more and very preferably about 0.40 or more. It is to be understood that a first oligomerization catalyst having a certain maximum SFC may be combined with an second oligomerization catalyst having a certain minimum SFC (as listed above), into a preferred combination of oligomerization catalysts.

In order to broaden the distribution of LAOs produced in the process it is preferred that the first oligomerization catalyst have a SFC 0.10 or more than the SFC of the second oligomerization catalyst, more preferably 0.15 or more, very preferably 0.20 or more and especially preferably 0.30 or more.

Although not critical, it is preferred that the molar ratio of the first oligomerization catalyst to the second oligomerization catalyst be from about 0.01 to about 99, more preferably about 0.05 to about 20.

It is preferred that both the first and second oligomerization catalysts are similar to each other, differing only in minor structural details both otherwise similar. In this case the rates of oligomerization will also very likely be similar as will the process conditions needed, since the two catalysts are so similar. Such a type of oligomerization catalyst is an iron or cobalt complex of a ligand of the formula:

wherein: R¹, R², and R³ are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group, provided that any two of R¹, R², and R³ vicinal to one another taken together may form a ring; R⁴ and R⁵ are each

independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group provided that R¹ and R⁴ and/or R³ and R⁵ taken together may form a ring; and R⁶ and R⁷ are each independently aryl or substituted aryl. In another preferred form of (I), R¹ and R⁴ taken together form a ring, and/or R³ and R⁵ taken together may form a ring, see U.S. Patent 7,442,819.

It is preferred that the complex of (I) is an iron complex.

In an especially preferred class of such ligands (I), and specifically (IV), R⁶ is (II) and R⁷

(II) (III)

wherein R¹⁰, R¹⁴, and R¹⁵ are each independently hydrocarbyl, substituted hydrocarbyl or a functional group other than fluoro, and R¹¹ to R¹³ and R¹⁶ to R¹⁸ are each

independently hydrogen hydrocarbyl, substituted hydrocarbyl or a functional group, and R¹⁹ is hydrogen or fluoro, and any two of R¹⁰ through R¹⁹ vicinal to one another may form a ring. More preferably, in (IV) and its iron complexes, R¹⁰, R¹⁴, and R¹⁵ are each independently alkyl containing 1 to 12 carbon atoms, and/or R¹¹ to R¹³ and R¹⁶ to R¹⁹ are each independently hydrogen or alkyl containing 1 to 12 carbon atoms, and/or R¹, R², and R³ are hydrogen, and/or R⁴ and R⁵ are both methyl or hydrogen. The iron or cobalt complexes of (I) and contains only one molecule of the ligand (I) per iron or cobalt atom present.

In an iron or cobalt complex of (I), (I) is usually thought of as a tridentate ligand coordinated to the iron or cobalt atom through the two imino nitrogen atoms and the nitrogen atom of a pyridine ring. It is generally thought that the more sterically crowded it is about the iron or cobalt atom, the higher the molecular weight of the product produced.

In order to make LAOs, and especially to make them in a process wherein the SFC is relatively high (such as from about 0.75 to about 0.98), increased steric crowding about the iron atom is desired, when compared to oligomerization catalysts having lower SFCs, see for instance US Patent Application Publication 20120302809 in which such catalysts are described and used in oligomerizations.

For oligomerization catalysts which have relatively low SFCs (about 0.3 to about 0.5) see for instance, W02005/092821 where it is demonstrated that the iron complex, in which R⁴ and R⁵ are both hydrogen and R⁶ and R⁷ are both phenyl, has a Schulz-Flory constant of about 0.29 (this reference states the Schulz-Flory constant is about 0.4, but this is apparently based incorrectly on the weight fraction of the olefins produced, not correctly the mole fraction). In G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221 -2231 (2000), which is hereby included by reference, a ligand, in which R⁴ and R⁵ are both hydrogen and R⁶ and R⁷ are both 2-methylphenyl, gives an oligomerization at 50°C in which the Schulz-Flory constant is reported to be 0.50. See also

WO201 1022373 for a discussion of catalysts which give product mixtures having low SFCs.

Oligomerization catalysts of (I) with "moderate" SFCs (about 0.5 to about 0.75) are described in B.L. Small, et al., J. Am. Chem. Soc, vol. 120, p. 7413-7144 (1998), G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221 -2231 (2000), and US Patents 6,103,946 and 6,710,006 both of which are hereby included by reference.

In general the synthesis of ethylene oligomerizations catalysts containing (I) are described in B.L. Small, et al., Macromolecules, vol. 132, p. 2120-2130 (1999), G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221-2231 (2000), U.S. Patents 6, 103,946, 6,710,006, 7,223,893, 7,238,764, 7,319, 083, 7,742,819, 7,547,783, and World Patent Application 20060178490, all of which are hereby included by reference. Many of these references also have examples and/or descriptions of the processes using these catalysts to prepare LAOs from ethylene. Whatever the SFC of the oligomerization catalyst containing (I) is, process conditions useful for another catalyst with a different SFC are applicable. In other words such process conditions such a pressure, temperature, liquid medium, etc. .are common to all of these oligomerization catalysts. The fact that two such oligomerization catalysts are present in the process does not change this conclusion.

Overall process types useful and conditions for the oligomerization process containing (I) are described in U.S. Patent 6,534,691 , 6,555,723, 7,053,202, and 7,053,259, all of which are hereby included by reference.

If other types of oligomerization catalysts are used, the conditions used for the process are the same as is reported to be useful for the individual catalysts themselves.

Other relatively small aryl groups may also be used for R⁶ and R⁷, such as 1-pyrrolyl, made from substituted or unsubstituted 1-aminopyrrole (see for instance World Patent Application 2006/0178490, which is hereby included by reference).

Analogous substitution patterns to those carried out in phenyl rings may also be used to attain the desired degree of steric hindrance, and hence the desired SFC. Aryl groups containing 5-membered rings such as 1 -pyrrolyl may be especially useful for obtaining the desired SFCs, since they are generally less sterically crowding than 6-membered rings. Preferred aryl groups for R⁶ and R⁷ are phenyl and substituted phenyl.

Since in the present process the object is to produce a series of oolefins using two different oligomerization catalysts, it is preferred that little or no ethylene

polymerization catalyst is present. By an "ethylene polymerization catalyst" is meant a catalyst that homopolymerizes ethylene and copolymerizes ethylene and one or more LAOs. To test whether a catalyst is an ethylene polymerization within the meaning herein, the present process is run at the process conditions to be used, except the ethylene oligomerization catalysts are not present, the only monomer being ethylene. The cocatalyst/catalyst ratio may be adjusted so that this ratio remains the same in the test experiment, as in the proposed present process. The number average molecular weight of the resulting homopolyethylene is measured using standard methods, such as size exclusion chromatography, and also using appropriate standards. Care should be taken, if low molecular weight polymeric products are made, to ensure that lower molecular weight components are not lost. The product from this test of a suspected "ethylene polymerization catalyst" must have a number average molecular weight of at least 1500 for the catalyst being tested to be considered an ethylene polymerization catalyst (this number average molecular weight corresponds to a SFC of approximately 0.982 or more). If the number average molecular weight is less than 1500, it is considered an oligomerization catalyst. Preferably, any ethylene polymerization catalyst present is less than 1 .0 mole percent of total number of moles of the oligomerization catatlysts present, more preferably less than 0.1 mole percent. Most preferably there is no ethylene polymerization catalyst present. These amounts for the ethylene

polymerization catalyst present do not include adventitious or normal impurities in any of the oligomerization catalysts present.

In the Examples, the following compounds are used.

Compound A: This compound is a complex of FeCI₂ with a species of ligand (I). In this species R¹ through R⁵ are hydrogen, and R⁶ and R⁷ are 2-methylphenyl. The synthesis of this complex is described in G.J. P. Britovsek et. al., Chem. Eur. J., vol. 6 (No. 12), p. 2221-2231 (2000), at p. 2229.

Compound B: This compound is a complex of FeCI₂ with a species of ligand (I). In this species R¹ through R³ are hydrogen, R⁴ and R⁵ are methyl, and R⁶ and R⁷ are 1-naphthyl. The synthesis of this complex is described in G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221-2231 (2000), at p. 2229.

Compound C: This compound is a complex of FeCI₂ with a species of ligand (I). In this species R¹ through R³ are hydrogen, R⁴ and R⁵ are methyl, and R⁶ is 2,6- dimethylphenyl, and R⁷ is 2-isopropylphenyl. The synthesis of this complex is described in Examples 1 , 2 and 3 of US Patent Application Publication 20120302809.

Example 1

This Example is partially adapted from Run 4, Table 3, of G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221-2231 (2000).

A 1 I stainless steel reactor was dried and then 0.5 I of isobutene was added and then methylalumoxane was added. The reactor temperature was adjusted to 50°C, and then ethylene was added to a pressure of 5 bar. Then 6 μηηοΙ of Compound A toluene was injected into the reactor. The molar ratio of MAO to Compound A was 1000. The ethylene pressure was maintained at 5 bar for one hour with stirring. Then the reaction was ended by venting volatiles and the contents of the reactor extracted with toluene. The toluene solution was washed with 1 M hydrochloric acid, water and then dried over MgS0₄. The toluene solution was analyzed by quantitative gas chromatography analysis and the SFC was calculated to be 0.50.

Since the SFC was relatively low at 0.50, it is mostly likely that Compound A would be a second oligomerization catalyst in the present process. Substitution of 70 mole percent of Compound A by an equimolar amount of Compound B or Compound C results in a product which is enriched in relatively higher molecular weight LAOs such as 1-tetradecene or 1 -eicosene.

Example 2

This Example is partially adapted from Run 5, Table 3, of G.J. P. Britovsek et. al., Chern. Eur. J., vol. 6 (No. 12), p. 2221-2231 (2000). The procedure was the same as Example 1 , except Compound B was used instead of Compound A. The SFC was calculated to be 0.63.

Since the SFC was 0.63 Compound B may be either the first or second oligomerization catalyst in the present process. If Compound B is used as a first oligomerization catalyst, substitution of 50 mole percent of Compound B by an equimolar amount of Compound A results in a product which is enriched in relatively lower molecular weight LAOs such as 1-hexene. If Compound B is used as the second polymerization catalyst, Substitution of 30 mole percent of Compound B by an equimolar amount of Compound C results in a product which is enriched in relatively higher molecular weight LAOs such as 1-tetradecene or 1 -eicosene.

Example 3

This Example is partially adapted from Example 7 of US Patent Application Publication 20120302809.

The reaction was run in a 1 I Autoclave Engineering Zipperclave® using 700 ml of o-xylene as the solvent. Modified methylalumoxane 3A was used as the activator and the ratio of Al to Fe was 2880. Ethylene was added and the reaction allowed to run for 30-60 min at a temperature of 120°C. The Zipperclave® was cooled, the ethylene vented, and the solution containing the product was analyzed by gas chromatography for those olefins having 4 to about 30 carbon atoms. From this the SFC was calculated to be 0.82.

Since the SFC was a relatively high 0.82, Compound C is likely to be a first oligomerization catalyst in the present process. If Compound A or Compound B is used as a second oligomerization catalyst, substitution of 50 mole percent of Compound C by an equimolar amount of Compound A or Compound B results in a product which is enriched in relatively lower molecular weight LAOs such as 1 -hexene.

These Examples 1-3 illustrate specific catalysts which may be used in the present process. None of these illustrated catalysts are restricted to being the first or second oligomerization catalysts, but the individual Examples point out their likely uses, given their individual SFCs. These Examples also show what process conditions are useful for the process, and that process conditions useful for any particular first or second oligomerization catalyst which is a complex of (I), are useful for the other oligomerization catalyst present in the process. These catalysts, and process conditions with them, are described in the various references cited above.

Claims

1. A process for the production of linear a-olefins, comprising, oligomerizing ethylene to form linear α-olefins comprising, carrying out said oligomenzation with a first oligomenzation catalyst that forms said linear α-olefins from ethylene in proportions that is a Schulz-Flory distribution, and a second oligomenzation catalyst that forms said linear α-olefins from ethylene in proportions that is a Schulz-Flory distribution, and provided that said first oligomenzation catalyst has a Schulz-Flory constant that is greater than a Schulz-Flory constant for said second oligomenzation catalyst, said Schulz-Flory constants being measured under process conditions, and provided that less than 1 .0 mole percent of an ethylene polymerization catalyst is present, said percentage based on the total moles of said first and said second polymerization catalysts present..

2. The process as recited in claim 1 wherein said Schulz-Flory constant of said first oligomenzation catalyst is at least 0.10 greater than said Schulz-Flory constant of said second oligomenzation catalyst.

3. The process as recited in claim 1 wherein said Schulz-Flory constant of said first oligomenzation catalyst is at least 0.20 greater than said Schulz-Flory constant of said second oligomenzation catalyst.

4. The process as recited in any one of claims 1 to 3 wherein said first oligomenzation catalyst has a Schulz-Flory constant of about 0.95 or less.

5. The process as recited in any one of claims 1 to 3 wherein said first oligomenzation catalyst has a Schulz-Flory constant of about 0.90 or less.

6. The process as recited in any one of claims 1 to 5 wherein said second oligomenzation catalyst has a Schulz-Flory constant of about 0.30 or more.

7. The process as recited in any one of claims 1 to 5 wherein said second oligomenzation catalyst has a Schulz-Flory constant of about 0.40 or more.

8. The process as recited in any one of claims 1 to 7 wherein said first oligomenzation catalyst and said second oligomenzation catalyst is an iron or cobalt complex of a ligand of the formula:

wherein:

R¹, R², and R³ are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert functional group, provided that any two of R¹, R², and R³ vicinal to one another taken together may form a ring;

R⁴ and R⁵ are each independently hydrogen, hydrocarbyl, substituted

hydrocarbyl or an inert functional group provided that R¹ and R⁴ and/or R³ and R⁵ taken together may form a ring; and R⁶ and R⁷ are each independently aryl or substituted aryl; and further provided that R¹ and R⁴ taken together form a ring, and/or R³ and R⁵ taken together may form a ring.

d in claim 8 wherein R⁶ is (II) and R⁷ is (III),

(II) (III)

wherein:

R¹⁰, R¹⁴, and R¹⁵ are each independently hydrocarbyl, substituted hydrocarbyl or a functional group other than fluoro;

R¹¹ to R¹³ and R¹⁶ to R¹⁸ are each independently hydrogen hydrocarbyl, substituted hydrocarbyl or a functional group;

R¹⁹ is hydrogen or fluoro; and provided that any two of R¹⁰ through R¹⁹ vicinal to one another may form a ring.

10. The process as recited in any one of claims 1 to 9 wherein said complex is complex of iron.

1 1 . The process as recited in any one of claims 1 to 10 wherein none of said ethylene polymerization catalyst is present.