EP0427830A1

EP0427830A1 - Method for adjusting molecular weight distribution and molecular weight of oligomerization/polimerization product of ethylene

Info

Publication number: EP0427830A1
Application number: EP19900907088
Authority: EP
Inventors: Erkki Pulkkinen; Liisa KIVIMÄKI; Rauno Logren; Salme Koskimies; Marjaana SIIRILÄ
Original assignee: Neste Oyj
Current assignee: Neste Oyj
Priority date: 1989-06-05
Filing date: 1990-05-23
Publication date: 1991-05-22
Also published as: JPH04503375A; WO1990015085A1; FI892742A; FI85588B; FI85588C; FI892742A0

Abstract

L'invention concerne un procédé d'ajustage de la répartition de la masse moléculaire, et de la masse moléculaire de produits d'oligomérisation/polymérisation d'éthylène, consistant à utiliser un ylure de nickel lié à un polystyrène réticulé, ou à utiliser avec un activeur, en tant que catalyseur dans le processus d'oligomérisation/polymérisation d'éthylène. Selon le procédé, l'on ajuste la répartition et/ou la masse moléculaire du produit, en modifiant le système de catalyseur par variation du degré de réticulation du polystyrène servant de support de catalyseur, et/ou de la qualité et/ou de la quantité de l'activeur.The invention relates to a method for adjusting the molecular weight distribution and the molecular weight of ethylene oligomerization / polymerization products, comprising the use of a nickel ylide linked to a crosslinked polystyrene, or for use with an activator, as a catalyst in the oligomerization / polymerization process of ethylene. According to the process, the distribution and / or the molecular mass of the product is adjusted, by modifying the catalyst system by varying the degree of crosslinking of the polystyrene serving as catalyst support, and / or the quality and / or the amount of activator.

Description

Method for adjusting molecular weight distribution and molecular weight of oligomerization/polymerization product of ethylene

The invention relates to a method for adjusting molecular weight distribution and molecular weight of oligomerization/polymerization product of ethylene, wherein nickel ylide linked to a cross-bonded ^■\ polystyrene or to be used together with a promoter is used as a catalyst in the oligomerization/polymerization process of ethylene.

-olefines have, as is well known, many applications depending on the length of the olefine chain. E.g. ->12'^20 olefines are used for

^■J5 preparing corresponding bio-decomposing detergents of sulphonate and ethoxilate type. Alcohols made of Cg-C_]^ α-olefines have important applications especially as softener alcohols. 1-decene is in turn used to an ever-increasing extent for making synthetic lubricants of poly-α-olefine type. Short-chain C^-Cg olefines have found use as

20 comonomers of polyolefines, especially LLDPE.

Several catalysts are thus known for dimerization, oligomerization and polymerization of olefines. E.g. the GB patent publication No. 1239 812 describes a catalyst for oligomerization of olefines com-

25 prising a metalline organic polymer, which contains a metal atom of the group VIII and a compound behaving like a Lewis acid. The known catalysts for oligomerization of olefines are generally organometallic compounds, such as organoaluminium compounds, which are in contact with a transition metal compound comprising low molecular weight 0 ligands, which include substances of the group V or VI (nitrogen, oxygen, phosphor or sulphur). The US patent No. 4 115 468 describes a two-component catalyst, which contains an organoaluminium compound and for example a vinyl-containing siloxane rubber, which is bonded to a nickel salt for dimerization of olefines. 5

Nowadays, more and more efficient ethylene oligomerization catalysts are being developed continuously, which provide a high reaction 1 speed and yield at low temperatures and pressures. The US patents Nos. 4293 502 and 4293 727 describe related nickel catalysts of ylide type for oligomerization of ethylene.

g Using nickel phosphine catalysts linked to a cross-bonded polystyrene as an oligomerization catalyst is described in the US patent No. 3 933 770 (halogenated cross-bonded polystyrene as a polymer) and in the DE patent- publication No. 2230739 (styrene divinyl benzene copolymer as a polymer) . Catalysts of the above-mentioned type are ^■JQ beneficial, since they can be recovered from the reaction mixture and recycled.

This patent application relates to a method, by means of which the molecular weight distribution and molecular weight of oligomerization ^■J5 products of ethylene can be adjusted, when catalysts of the type described above are used as catalysts.

The inventive method for adjusting the molecular weight distribution and molecular weight of oligomerization products of ethylene is 20 mainly characterized in that the product distribution and/or molecular weight is adjusted by modifying the catalyst system by varying the cross-bonding degree of polystyrene serving as a catalyst carrier and/or the quality and/or quantity of the promoter.

5 The preferred embodiments of the invention have the characteristics according to the subclaims.

By means of the method, the product distribution of the products concerned can be controlled within a relatively large range (MW -= 0 0 - 115 000) in the direction of either long- or short-chained α- olefines depending on the promoters utilized or the cross-bonding degree of polystyrene serving as a carrier.

The invention is especially related to methods, wherein the oligo- 5 merization of ethylene is performed by using as a catalyst the nickel ylide according to the following formula I, which is either bonded to a carrier, especially a cross-linked polystyrene containing preferably 1-4% divinyl benzene or used in combination with triphenyl phosphine or bis-cyclooctadiene nickel chelate.

Ph Ph

(1) (COD)₂Ni+Ph₃P+Ph₃P=CHCOPh Ph CH (I)

II

Ph₃P Ph

The bonding to a cross-linked polystyrene (1-4% divinyl benzene) has been performed chemically and the catalysts then correspond to the structure II achieved with the reactions 2 and 3.

P CCCKgBr

CgEβOK

C0D)2Ni = bis-cyclooctadiene nickel PS = bonding to polystyrene

The invention is especially related to methods, wherein the molecular distribution of an oligomerization product prepared with a nickel ylide catalyst is on the basis of the application adjusted in the direction of either long- or short-chained α-olefines. A significant transition into the range of long-chained, even polymer products is possible, when the cross-bonding degree of a polystyrene carrier increases (e.g. polystyrene cross-bonded by 2% or 4%). An increase in bis-cyclooctadiene in the oligomerization phase also brings about transition of the oligomerization distribution into the range of long-chained products. A suitable quantity of (COD^Ni is 3 to 5 times the quantity of nickel contained in the catalyst.

An excess (0,5-1,0 mol) of triphenyl phosphine in connection with an increase in the ylide nickel catalyst, in contrast, controls the oligomerization distribution in the direction of α-olefine products boiling at a lower temperature.

When adjusted in accordance with the method of the invention phosphine catalysts directly produce high-quality LLPDE.

Depending on the molecular weight and its distribution, the inventive reaction products can be used e.g. for adjusting the working proper¬ ties of polyolefines and as reactants for synthetic lubricants. Products with a higher molecular weight can already as such be utilized as diverse polyethylene grades.

Suitable solvents for completing the oligomerization reaction of ethylene include aromatic or aliphatic hydrocarbons or their mixtures.

Methods suitable for recycling the catalyst bonded to the carrier include e.g. film separation methods (1-% and 2-% cross-bonded poly¬ styrene) or filtration (polystyrene cross-bonded by 4%).

A more detailed preparation method od catalysts according to the invention is as follows.

Preparation of ylide (catalyst I) :

The following reaction will occur: phosfoniumsalt

ylide

In the purification of the first phase, the solution is decanted from the top of the precipitate, sucked from the top of the precipi- tate with a Pasteur-pipette or precipitated with an excess of methanol, and in the second phase the solution is sucked from the top of the precipitate with a double-headed needle or decanted from the top of the gel. The precipitate is flushed with water and THF or methanol. The product is dried with a Leybold vacuum pump.

Preparation of ylide (catalyst II) bonded to polystyrene:

The following reaction is performed e.g. in a 50 ml Erlenmeyer flask:

a)

phosfoniumsalt

Preparation:

(1) The phosphinated PS is placed in a reaction vessel in a nitrogen cabinet.

(2) THF is added in the nitrogen cabinet.

(3) Swelling by mixing. (4) w-bromine acetophenon is added to the vessel and the mixing is continued at 20°C for 18 hours. (5) Pressure filtration in the nitrogen cabinet through a glass fiber filter. (6) The product is washed with THF and water.

b) The following reaction is performed in the Erlenmeyer flask:

ylide Preparation:

(1) The phosphonium salt is placed in the reaction vessel.

(2) THF is added in a nitrogen bag.

(3) Mixing at 20°C for one hour.

(4) The K-phenoxide solution is added with a double-headed needle.

(5) Pressure filtration in a nitrogen bag. (6) Washing of the product THF (10 ml), THF: H₂0 (1:1) (50ml), H₂0 (60 ml) and THF (40 ml) .

The invention can be described in more detail by means of the following examples.

EXAMPLES 1-4

A pressure reactor was loaded with a catalyst I of formula I and a solvent, and in Examples 3 and 4, (COD^Ni in a nitrogen cabinet. The reactor was heated to 50°C and pressurized with ethylene to a pressure of 50-60 bar. The pressure was held constant (50 bar) by means of the ethylene supply during the entire reaction (2 h). The gaseous and liquid products were analyzed gas chromatographically and the yield of solids was determined by weighing and the molecular weight distribution was determined by means of a gel permeation chromatographic (GPG) method. 1 The results and the test conditions are shown in Table 1 as well as in Figures 1 and 2. The results indicate that a molecular weight varying extensively is achieved in products, which can be adjusted e.g. by means of (C0D)₂Ni, the addition of which will result in

5 longer-chained polymer products.

EXAMPLES 5-10

A pressure reactor was loaded with a catalyst II of formula II and a

^■|0 solvent in a nitrogen cabinet. In the oligomerization, the ethylene pressure was applied first, the mixing was then switched on and the heating of the mixture was started. The reactor was heated to 75°C and pressurized with ethylene to a pressure of 50-55 bar. The reaction time was 4 h, 6 h, 9 h, 12 h and 15 h. All ethylene was consumed in

-|5 Examples 5 and 6. The gaseous and liquid products were analyzed gas chromatographically and the yield of solid substances was determined by weighing and the molar mass distribution was determined with a GPC. The results and the test conditions are shown in Tables 3 and 4 as well as in Figures 3-5. hen the results are compared with the

20 results of Examples 1-4, it can be seen that a catalyst linked to a cross-bonded polystyrene produces a molecular mass varying widely in the polymerization product of ethylene and that the product distri¬ bution and the molecular weight can be controlled by varying the cross-bonding degree (0-4%) of polystyrene. A low cross-bonding

25 degree (ca. 1%) produces a large quantity of Cg-C₂g products and a high cross-bonding degree produces polymers of a higher-order.

EXAMPLES 11-15

30 Oligomerizations performed with a catalyst II according to formula II and containing a 1-% cross-bonded PS (Table 4).

Effect of the addition of PPh₃

5 Catalyst: 11-12.288 1 PS ylide 3.14 g

(COD)₂Ni 1.9 g/ 6.9 mol PPh₃ 1.65 g/6.3 mol

5 yield 13.0 g

Oligomerization

The catalyst samples were weighed in brown phials, 10 ml toluene was ^■|0 added and the phials were stored in a nitrogen cabinet (parafilm around the cork).

As an autoclave was used a 300 ml Parr steel vessel with motor mixing.

^■J5 The catalyst and toluene were placed in the autoclave in a nitrogen cabinet, the autoclave was pressurized to 48 bar, the mixing was switched on and the heating of the reaction mixture was started by means of an electric bath. The mixture was rapidly heated to 50°C, after which the mixture was heated to the reaction temperature 75°C

20 ^at a slow heating rate to avoid an exothermic reaction. After the temperature of 75°C had been reached and ethylene had started to consume, the supply of ethylene into the mixture was started. In contrast to the previous specifications, a continuous supply of ethylene was used in the oligomerization and the constant pressure 5 was 48 bar.

The results of the oligomerization reactions are summarized in Table 4 and drawings 6-8. The reaction mixture 11 was heated to 65°C by means of a rapid heating control, after which the heating advanced 0 at a slow heating rate. The reaction temperature increased to over 75°C (max. 138°C) for 6 minutes.

In the experiments 12 and 13, the quantity of PPh₃ was 1.5 times the molar mass of PPh₃ used in the preparation of the catalyst. In the 5 experiment 14, the quantity of PPh₃ is double with respect to the experiments 12 and 13. 1 In the experiment 15, the reaction time is 4 hours (like in 12 and 13), but the autoclave with its reaction mixture was pressurized to 34 bar at room temperature for 2 days, during which period the reaction advanced, consuming all ethylene.

5

Gas chromatography and mass spectrography were used for analyzing the products. In the quantitative analysis of the liquid products the internal standard was decane. When the mass of wax (polyethylene) was determined, the mass of the catalyst used in the reaction was

■JQ subtracted from the quantity of dried was filtered separately from the liquid phase.

A gas sample was taken from the reaction mixture into the gas supply loop (100 μl) of a gas chromatograph (Perkin Elmer 8500) after the

■|c completion of the reaction, when the reaction mixture was at room temperature. The peaks provided by the gas chromatograph were ident¬ ified by means of mass spectrography as ethylene, 1-butene, 1-hexene and toluene. The retention time of toluene was further tested by heating only toluene in the autoclave to the reaction temperature

20 ^a--m- by taking a gas sample thereof. As a column was used a silica capillary column, which was 25 m long and contained a BP 1 5 μm thick liquid phase.

The quantity of the gases was calculated from the weighing results 25 of the autoclave by means of single responses (autoclave weighing when the gases are inside and after they have been released) .

The formation of the gaseous products in the oligomerization reaction was followed. As early as after two minutes from the start of the 30 reaction a small amount of butene as well as hexene had formed. The share of both components grew as the reaction advanced.

An addition of PPh₃ to the reaction transfers the oligomer distribu¬ tion to light alcanes. In the experiment 14, in which the quantity 35 of PPh was triple the molar mass of PPh₃ used for preparing the catalyst, the share of 1-butene of the oligomer production was 64.7% and in the experiments 12 and 13 50.9% and 47.5%. In these reactions 1 the share of C -C10 of oligomers was as high as 96%.

The share of wax of the total yield decreases due to the addition of PPh₃ (76.5% --> as low as 23.1%), but the activity of the catalyst 5 will decrease simultaneously.

To summarize the oligomerization of ethylene performed with catalysts linked to polystyrene, it is now understood that a catalyst linked to a 1-% cross-bonded polystyrene produces oligomers and also wax.

^■JO The quantity of wax can be decreased by admixing triphenyl phosphine into the autoclave together with the catalyst. However, the total activity of the catalyst will then decrease as a function of the molar mass of the triphenyl phosphine added. Owing to triphenyl phosphine, the share of light C^-C^Q 1-alkenes increases in comparison

^■J5 with oligomers. The addition of triphenyl phosphine to the reaction causes an increase in the weight-average molecular mass of wax and also an increase in the numeral-average molecular mass. When the quantity of triphenyl phosphine used for preparing the catalyst is reduced, the total activity of the catalyst decreases, but the share

20 of ^wax °f the total products simultaneously decreases and the share of light 1-alkenes increases.

The most active of the catalysts linked to a cross-bonded polystyrene was the catalyst containing the 1-% PS, with respect to the production 5 °f both oligomers and wax. The share of wax of the total product quantity was in the products of the 1-% PS containing catalyst less than 50%, when the catalyst dispersion contained 59 mg/40 ml nickel.

The share of wax increased as the cross-bonding of polystyrene grew.

The 4-% cross-bonded PS containing catalyst with the weakest total 0 activity produced relatively the highest amount of wax, i.e. 90% of the total product quantity.

In addition to the cross-bonding of PS, the increase in the share of wax was affected by the low amount of catalyst (nickel) , an increase 5 in the solvent volume and a decrease in the reaction temperature.

The molecular weight distributions varied widely on waxes. The lowest polydispersity value 4 was found in the waxes produced by the 4-% cross-bonded PS containing catalyst and the highest value 94 on 2-% waxes.

The 1-% cross-bonded PS containing catalyst produced wax, whose polydispersity was 12. Mw was 5600 and Mn 460. As the cross-bonding of polystyrene increases, it resulted in polymers of ethylene with a higher molecular mass. The highest molecular masses were achieved with 2-% cross-bonded PS containing catalysts.

A catalyst containing a non-cross-bonded PS (Mw 209000) produced wax with a low molecular mass.

The distribution of oligomers concentrated in light 1-alkenes in products produced by 1-% and 2-% cross-bonded PS catalysts. The share of Cg-C^_Q of alkenes was the highest in 2-% PS products (32- 57%) and decreased in 1-% PS products (21-37%). The amount of light oligomers was the lowest, when the carrier was a 4-% cross-bonded PS, whereby the distribution peak of oligomers was in heavy alkanes (share of Cg-C^Q 8-22%). The distribution peak shifted to heave alkanes also in connection with 1-% and 2-% PS products, when the catalyst dispersion was diluted.

Table 1. Oligomerization of ethylene with NI ylide catalyst a)

Example Catalyslt Solvent Reaction Olig. (%) Solids Cat. act. Product distributions Liquid mg/Ni time (h) C₆-C₂₈ - (%) g/g Ni

Mn Mw Mv D C -C₂₈ -

1 4,17 toluene 2 72.9 27.1 6451 50 330 270 3.8 Fig. 1

2 4,17 hexane 2 47.8 52.2 5971 80 290 240 3.9 Fig. 2

3 4,17 toluene + 2 0.1 99.9 10935 240 1100 900 4.7 - (COD)₂Ni

4 4,17 hexane + 2 0.3 99.7 10168 120 520 430 4.2 (COD)₂Ni

a) Catalyst I; conditions: p - 50 bar, t - 50°C, ethylene, solvent volume 300 ml continuous supply 34 mmol/1 b) (C0D)₂Ni - bis-cyclooctadiene nickel

Table 2. Oligomerization of ethylene with carrier-bonded Ni ylide catalyst (a)

Example Cat, (II) Cat./mg/Ni Reaction Olig. (%) Solids Cat. act. Product distribution (b) time (h) C₆-C₂₈ - (%) g/g Ni (C -C₂₈ =)

5 1% PS 80 4 81.2 18.8 305 Fig. 3 6 59 4 39.7 60.3 680 Fig. 4 7 37 4 13.5 86.5 343 Fig. 5 8 2% PS 76 6 24.1 75.9 104 Fig. 6 9 26 12 6.7 93.3 255 Fig. 7 10 4% 07 15 9.6 90.4 30

(a): Cat. II: Conditions t - 75°C, p = 50-55 bar (single supply) (b) : Molecular weight distributions shown in Fig. 3

Table 3. Molecular masses of waxes (Examples 5-10)

Cross-bonding Example degree of PS Mw Mn Mv D

1% 7 8900 860 7000 10.4 9000 860 7000 10.4

1% 6 5600 460 4000 12.1 5500 460 3900 12.0

2% 8 91000 1110 57000 82.0 90000 1080 55000 83.9

2% 9 111000 2040 72000 54.6 115000 1980 74000 57.8

4% 10 57000 1960 42000 29.1 58000 1880 42000 30.8

Table 4. Oligomerization performed with 1-% cross-bonded PS conatining catalyst

Example Catalyst PPH₃ Ni con¬ Olig. yield Share of C4-C 0 Total Share of wax Catalyst Product mass mass tained ^c4"^c28 of olig. yield yield of total yield activity distributi

(g) (mg) in cat. (mg) (%) (mg) (%) g tot/g (Fig.) (mg) Ni

11 1.91 - 59.6 17934 40.4 76189 76.5 1274 8

12 1.87 355 58.3 8414 89.1 12289 31.5 212 9

13 1.90 348 59.0 8746 94.3 11253 22.3 191 10

14 1.88 731 58.7 4957 96.5 6713 26.2 114 11

15 1.84 712 57.2 1461 75.3 12

Solvent toluene 50 ml

Reaction temperature (inner T) 75°C

Ethylene pressure 48 bar

Reaction time 4 h (12-15), 8 h (11)

Claims

1. Method for adjusting molecular weight distribution and molecular weight of oligomerization/polymerization product of ethylene, wherein nickel ylide linked to a cross-bonded polystyrene or to be used together with a promoter is used as a catalyst in the oligomerization and/or polymerization process of ethylene, characterized in that the product distribution and the molecular weight are adjusted by modifying the catalyst system by varying the cross-bondning degree of polystyrene serving as a catalyst carrier and/or the quality and/or quantity of the promoter.

2. Method according to claim 1, characterized in that the cross- bonding degree is varied in the range of 0-4% for achieving different oligomerization and/polymerization products, whose average molecular weight is in the range Mw - 1000-115000.

3. Method according to claim 1 or 2, characterized in that the catalyst system is modified by means of triphenyl phosphine and/or bis-cyclooctadiene nickel chelate.

4. Method according to any of the claims 1-3, characterized in that the quantity of nickel bis-cyclooctadiene (C0D) Ni is 3-5 times the quantity of nickel contained in the catalyst.

5. Method according to any of the claims 1-4, characterized in that the catalyst is modified by means of (C0D)₂Ni, when a large share of products with a high molecular weight is desired.

6. Method according to any of the claims 1-5, characterized in that the product distribution and the molecular weight are modified by means of a catalyst linked to a cross-bonded polystyrene by using a 1-% - 2-% cross-bonding degree, when products in the range of Cg- C₂₈, especially Cg-C g are desired, and a 4-% cross-bonding degree, when products of a higher order are desired.

7. Method according to any of the claims 1-6, characterized in that a higher quantity of triphenyl phosphine results in a higher quality of Gg-C₂ products, especially C4-C 0 products.