Catalyst system and a process for the production of a polyethylene in the presence of this catalyst system

Abstract

The invention relates to a catalyst system comprising I. a solid reaction product obtained by reaction of: (a) a hydrocarbon solution comprising (1) an organic oxygen containing magnesium compound or a halogen containing magnesium compound and (2) an organic oxygen containing titanium compound and (b) a mixture comprising a metal compound having the formula MeR.sub.nX.sub.3-n wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3 and a silicon compound of formula R.sub.mSiCl.sub.4-m wherein 0m2 and R is a hydrocarbon radical containing 1-10 carbon atoms wherein the molar ratio of metal from (b): titanium from (a) is lower then 1:1 and II. an organoaluminium compound having the formula AlR.sub.3 in which R is a hydrocarbon radical containing 1-10 carbon atoms.

Claims

1. A catalyst system comprising: (I) a solid reaction product obtained by reaction of: 1) a hydrocarbon solution comprising: (a) an organic oxygen containing magnesium compound; and (b) an organic oxygen containing titanium compound; and 2) a mixture comprising a metal compound having the formula MeR.sub.nX.sub.3-n, wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3, and a silicon compound of formula R.sub.mSiCl.sub.4-m, wherein 0m2 and R is a hydrocarbon radical containing 1-10 carbon atoms, wherein the molar ratio of metal from 2) to titanium from 1) is lower than 1:1; and (II) an organoaluminium compound having the formula AlR.sub.3 in which R is a hydrocarbon radical containing 1-10 carbon atoms.

2. The catalyst according to claim 1, wherein the reaction obtaining the solid reaction product further comprises 3) post treatment of the obtained solid reaction product with an aluminium compound having the formula AlR.sub.nCl.sub.3-n wherein R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3.

3. The catalyst according to claim 1, wherein the metal compound having the formula MeR.sub.nX.sub.3-n is an aluminium compound having the formula AlR.sub.nX.sub.3-n wherein X is a halogenide and R is a hydrocarbon radical containing 1-10 carbon atoms.

4. The catalyst according to claim 1, wherein the molar ratio of chlorine from R.sub.mSiCl.sub.4-m to oxygen from the organic oxygen containing magnesium and titanium compounds is lower than 3:1.

5. The catalyst according to claim 1, wherein the molar ratio of magnesium to titanium is lower than 3:1.

6. The catalyst according to claim 1, wherein the organic oxygen containing magnesium compound is a magnesium alkoxide.

7. The catalyst according to claim 6, wherein the magnesium alkoxide is magnesium ethoxide.

8. The catalyst according to claim 1, wherein the organic oxygen containing titanium compound is a titanium alkoxide.

9. The catalyst according to claim 8, wherein the organic titanium alkoxide is Ti(OC.sub.4H.sub.9).sub.4.

10. The catalyst according to claim 1, wherein the organoaluminium compound from (II) is triethylaluminium or triisobutyl aluminium.

11. A process for the production of a catalyst comprising: a) first reacting an organic oxygen containing magnesium compound and an organic oxygen containing titanium compound; b) followed by diluting with a hydrocarbon solvent, resulting in a soluble complex consisting of a magnesium alkoxide and a titanium alkoxide; c) after which reacting the hydrocarbon solution of said complex and a mixture comprising a metal compound having the formula MeR.sub.nCl.sub.3-n, wherein Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3, and a silicon compound of formula R.sub.mSiCl.sub.4-m, wherein 0m2 and R is a hydrocarbon radical containing 1-10 carbon atoms.

12. The process for the production of the catalyst according to claim 11, wherein the organic oxygen containing magnesium compound is a magnesium alkoxide and the organic oxygen containing titanium compound is a titanium alkoxide, and the metal compound is an aluminium compound having the formula AlR.sub.nCl.sub.3-n.

13. A process for the production of polyethylene comprising polymerising ethylene in the presence of a catalyst comprising: (I) a solid reaction product obtained by reaction of: 1) a hydrocarbon solution comprising: (a) an organic oxygen containing magnesium compound and (b) an organic oxygen containing titanium compound; and 2) a mixture comprising a metal compound having the formula MeR.sub.nX.sub.3-n, wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3, and a silicon compound of formula R.sub.mSiCl.sub.4-m, wherein 0m2 and R is a hydrocarbon radical containing 1-10 carbon atoms, wherein the molar ratio of metal from 2) to titanium from 1) is lower than 1:1; and (II) an organoaluminium compound having the formula AlR.sub.3 in which R is a hydrocarbon radical containing 1-10 carbon atoms.

14. A process for the production of an ethylene polymer comprising polymerising ethylene in the presence of a catalyst comprising: (I) a solid reaction product obtained by reaction of: 1) a hydrocarbon solution comprising: (a) an organic oxygen containing magnesium compound and (b) an organic oxygen containing titanium compound; and 2) a mixture comprising a metal compound having the formula MeR.sub.nX.sub.3-m, wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0n3, and a silicon compound of formula R.sub.mSiCl.sub.4-m, wherein 0m2 and R is a hydrocarbon radical containing 1-10 carbon atoms, wherein the molar ratio of metal from 2) to titanium from 1) is lower than 1:1; and (II) an organoaluminium compound having the formula AlR.sub.3 in which R is hydrocarbon radical containing 1-10 carbon atoms; wherein the ethylene polymer has an average molecular weight higher than 280,000 g/mol and lower than 10,000,000 g/mol, an average particle size (D.sub.50) in the range between 50 and 250 micrometer, and a bulk density in the range between 350 and 600 kg/m.sup.3.

15. The process of claim 14, wherein the average particle size (D.sub.50) is in the range between 50 and 200 micrometer.

16. The process of claim 14, wherein the bulk density is in the range between 400 and 600 kg/m.sup.3.

17. The catalyst according to claim 1, wherein when the catalyst is used in the production of polyethylene, the resulting polyethylene has a bulk density in the range between 350 and 600 kg/m.sup.3.

18. The catalyst according to claim 17, wherein when the catalyst is used in the production of polyethylene, the resulting polyethylene has a bulk density in the range between 400 and 600 kg/m.sup.3.

19. The catalyst according to claim 1, wherein n is less than 3.

20. The catalyst according to claim 1, wherein m is greater than 0.

21. The catalyst according to claim 1, wherein the metal compound comprises aluminium trichloride, ethyl aluminium dibromide, ethyl aluminium dichloride, propyl aluminium dichloride, n-butyl aluminium dichloride, isobutyl aluminium dichloride, diethyl aluminium chloride, diisobutyl aluminium chloride, triisobutyl aluminium, tri-n-hexyl aluminium, or a combination comprising one or more of the foregoing.

22. The catalyst according to claim 1, wherein the ratio is less than or equal to 0.38:1.

23. The catalyst according to claim 1, wherein the hydrocarbon solution consists essentially of the organic oxygen containing magnesium compound and the organic oxygen containing titanium compound.

Description

EXAMPLES

(1) All examples were carried out under a blanket of nitrogen.

(2) The solids content in the catalyst suspension was determined in triple by drying 10 ml of a catalyst suspension under a stream of nitrogen, followed by evacuating for 1 hour and subsequently weighing the obtained amount of dry catalyst.

(3) The average particle size (D.sub.50) of the catalyst was determined by the so called laser light scattering method in hexanes diluent, using a Malvern Mastersizer equipment.

(4) The average particle size and particle size distribution (span) of the polymer powders were determined by sieve analyses according to DIN53477.

Example I

Preparation of a Hydrocarbon Solution Comprising the Organic Oxygen Containing Magnesium Compound and the Organic Oxygen Containing Titanium Compound

(5) 100 grams of granular Mg(OC.sub.2H.sub.5).sub.2 and 150 milliliters of Ti(OC.sub.4H.sub.9).sub.4 were brought in a 2 liter round bottomed flask equipped with a reflux condensor and stirrer. While gently stirring, the mixture was heated to 180 C. and subsequently stirred for 1.5 hours. During this, a clear liquid was obtained. The mixture was cooled down to 120 C. and subsequently diluted with 1480 ml of hexane. Upon addition of the hexane, the mixture cooled further down to 67 C. The mixture was kept at this temperature for 2 hours and subsequently cooled down to room temperature. The resulting clear solution was stored under nitrogen atmosphere and was used as obtained. Analyses on the solution showed a titanium concentration of 0.25 mol/l.

Example II

Preparation of the Catalyst

(6) In a round bottom flask, equipped with a condensor, a stirrer and a dropping funnel, 300 ml of hexane were added. To this, 2.1 ml of 50% ethylaluminiumdichloride (EADC) in hexane (7.1 mmol Al) were added followed by 10 ml of SiCl.sub.4 (87 mmol). The mixture was warmed to 40 C. and the stirrer was started at 750 RPM. Via the dropping funnel, a mixture of 75 ml of the solution obtained in Example 1 and 6.5 ml of Ti(O-nC.sub.4H.sub.9).sub.4 (19 mmol) were added during a period of 2 hours. The slightly pink coloured suspension was subsequently refluxed for 2 hours, whereupon the mixture turned red. The suspension was subsequently cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen. Solids concentration was determined at 20 mg/ml. The catalyst had D.sub.50 of 6.7 m and a span of 0.9.

Example III

Preparation of the Catalyst

(7) Example II was repeated with the exception that no Ti(O-nC.sub.4H.sub.9).sub.4 was added and the amount of SiCl.sub.4 was 6.7 ml (57 mmol). Solids concentration was determined at 24 mg/ml.

Example IV

Preparation of the Catalyst

(8) Example III was repeated with the exception that the EADC amount was reduced to 2 mmol. Solids concentration was determined at 15 mg/ml.

Example V

Preparation of the Catalyst

(9) Example III was repeated with the exception that the amount of EADC was 4.4 mmol and the reflux time was reduced to 1 hour. Solids concentration was determined at 14 mg/ml.

Example VI

Preparation of the Catalyst

(10) Example III was repeated with the exception that the amount of EADC was 4.4 mmol and the temperature for the preparation of the catalyst was adjusted to 30 C.

Example VII

Preparation of the Catalyst

(11) Example III was repeated with the exception that the amount of SiCl.sub.4 was 40 mmol, the amount of EADC was 2.2 mmol and the temperature for the preparation of the catalyst was adjusted to 20 C.

Example VIII

Preparation of the Catalyst

(12) Example III was repeated with the exception that the 4.4 mmol of diethyl aluminium chloride was used instead of 7 mmols of EADC and the hydrocarbon solution from example 1 was dosed in 70 minutes.

(13) Solids concentration was determined at 24 mg/ml. The catalyst had a D.sub.50 of 9.6 m and a span of 0.8

Example IX

Preparation of the Catalyst

(14) Example III was repeated with the exception that the amount of EADC was 4.4 mmol. After the mixture was refluxed for 2 hours, the mixture was cooled down to ambient temperature. Via a dropping funnel, a mixture of 10 mmols triisobutyl aluminium and 50 ml hexane were added over 45 minutes time. The suspension was subsequently stirred for 1 hour at ambient temperature, filtrated and washed with hexane. The catalyst had a D.sub.50 of 6.4 m and a span of 0.9.

Example X

Preparation of the Catalyst

(15) Example III was repeated with the exception that 1 mmol of EADC was used instead of 7 mmols of EADC.

Example XI

Preparation of the Catalyst

(16) In a round bottom flask, equipped with a condensor, a stirrer and a dropping funnel, 300 ml of hexane were added. To this, 2.6 ml of 50% ethylaluminiumdichloride (EADC) in hexane (8.8 mmol Al) were added followed by 24.8 ml of n-butylSiCl.sub.3 (150 mmol). The mixture was warmed to 40 C. and the stirrer was started at 750 RPM. Via the dropping funnel, 150 ml of the solution from Example I was added over a period of 2 hours. The slightly pink coloured suspension was subsequently refluxed for 2 hours, whereupon the mixture turned red. The suspension was subsequently cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen.
Solids concentration was determined at 36 mg/ml.

Comparative Example A

Preparation of a Catalyst in the Absence of an Aluminium Compound Having the Formula AlRnCl3-n

(17) In a round bottom flask, equipped with a condensor, a stirrer and a dropping funnel, 300 ml of hexane were added. To this, 6.5 ml of SiCl.sub.4 (57 mmol) was added. The mixture was warmed to 40 C. and the stirrer was started at 750 RPM. Via the dropping funnel, 75 ml of the solution from Example I was added over a period of 2 hours. The white suspension was subsequently refluxed for 2 hours. The suspension was subsequently cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen.
Catalyst concentration was determined at 15 mg/ml. The catalyst had a D.sub.50 of 9.9 m and a span of 0.8

Comparative Example B

Preparation of a Catalyst Wherein the Aluminium Compound Having the Formula AlRnCl3-n and the Compound RmSiCl4-m Were Added Sequentially

(18) In a round bottom flask, equipped with a condensor, a stirrer and a dropping funnel, 300 ml of hexane were added. To this, 6.5 ml of SiCl.sub.4 (57 mmols) was added. The mixture was warmed to 40 C. and the stirrer was started at 750 RPM. Via the dropping funnel, 75 ml of the solution from Example I was added over a period of 2 hours. The white suspension was subsequently refluxed for 2 hours. The suspension was subsequently cooled down to ambient temperature. Then, a mixture of 4.4 mmol EADC and 50 ml of hexane were added in 30 minutes. The resulting mixture was heated to reflux temperature and kept at this temperature for 2 hours. The slurry was cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen.
Catalyst concentration was determined at 33 mg/ml.

Comparative Example C

Production of a Catalyst Wherein the Aluminium Compound Having the Formula AlRnCl3-n as Added in a Molar Ratio Aluminium:Titanium>1

(19) This catalyst was prepared in a similar procedure as in example II, but the extra Ti(O-nC.sub.4H.sub.9).sub.4 was omitted and the amount of EADC was increased to 70 mmols, which results in an Al to Ti molar ratio of 3.7.

Examples XII-XXIV and Comparative Examples D-F

Polymerizations in the Presence of the Catalysts According to Examples II-XI and According to Comparative Examples A-C

(20) The polymerizations were carried out in a 10 liter autoclave using 5 liter purified hexanes as a diluent. 8 mmols of tri-isobutylaluminium were added to the 5 liter purified hexanes. The mixture was heated to 75 C. and pressurized with ethylene. Subsequently a slurry containing the predetermined amount of a catalyst according to the Examples II-XI was dosed. The temperature was maintained at 75 C. and the pressure was kept constant by feeding ethylene. The reaction was stopped when approximately 475 grams of ethylene has been supplied to the reactor. Stopping was performed by de-pressurizing and cooling down the reactor. The reactor contents were passed through a filter; the wet polymer powder was collected, subsequently dried, weighed and analyzed.
The results are summarised in Table 1.

(21) The Examples XII-XXIV demonstrate that the polymers obtained with the catalyst according to Examples II-XI have a desirable lower average particle size compared with the polymer obtained with the catalyst according to Comparative Example A, often even when the catalyst yield obtained with the catalysts according to the invention is much higher compared to the catalyst from. Comparative Example A. Additionally, the catalysts according to Examples II-IX have a much higher catalyst activity than the catalyst according to Comparative Example A which was prepared without the use of EADC during the formation of the solid reaction product.

(22) The catalyst from Comparative Example B displays a good catalyst activity, but comparison with the results from the catalysts from Examples II to XI shows that the particle size of the polymer undesirably increases in case the EADC is not present as a mixture with SiCl.sub.4 because this component is dosed after the reaction product with SiCl.sub.4 has taken place. This demonstrates the necessity that the compound AlR.sub.nCl.sub.3-n must be present in the hydrocarbon solution containing the compound R.sub.mSiCl.sub.4-m

(23) Comparison of the catalysts according to Examples II-XI with Comparative Example C shows that the selection of the amount of the aluminium compound having the formula AlR.sub.nCl.sub.3-n is critical. The applied ratio of aluminium to titanium in Comparative Example C results in a very low bulk density and unacceptably high D.sub.50 of the polymer.

(24) TABLE-US-00001 TABLE 1 Polymerization results Milligrams Catalyst of catalyst Ethylene Bulk D.sub.50 of the from added pressure density polymer Example example [mg's] [bar] CY.sup.1) CA.sup.2) kg/m.sup.3) [m] Span [eta] [dl/g] XII II 40 6 11.3 1.5 404 171 0.6 21.4 XIII III 20 4.5 23.8 4.2 378 175 1 21.7 XIV IV 40 3 11.2 2.3 404 161 0.7 XV V 50 2.5 9.5 2.3 404 156 1.2 XVI V 25 3.5 17.3 2.9 415 176 0.8 XVII VI 50 2.5 8.7 2.6 410 148 0.7 XVIII VI 25 3.5 18.2 3.6 416 193 0.8 XIX VII 50 4 8.9 1.6 426 165 0.8 XX VII 25 5 18.5 2.2 455 208 0.6 XXI VIII 40 3 11.3 2.8 396 211 0.7 23 XXII IX 20 4.5 21.5 4 406 189 0.83 XXIII X 50 7.5 8.3 0.6 423 167 0.7 XXIV XI 50 6.5 6.9 0.5 364 119 0.8 D A 40 6 10.8 0.7 398 223 0.5 E B 34 3.5 13.4 2.7 387 238 0.45 F C 50 2.5 10 4.8 213 252 0.8 .sup.1)Catalyst Yield: kilograms polyethylene per gram of catalyst .sup.2)Catalyst Activity: kilograms polyethylene per gram of catalyst per hour per bar of ethylene .sup.3)[eta] intrinsic viscosity measured at 135 degrees Celsius in decaline.

Example XXV

Preparation of a Catalyst

(25) 400 ml of hexanes were added to a 0.8 L glass reactor, equipped with a condensor, a stirrer, baffles and a peristaltic pump. To this, 17.3 ml of SiCl.sub.4 (152 mmol) and 3.5 ml EADC (11.9 mmol) were added. The mixture was at ambient temperature when the stirrer rate was set at 1700 RPM. Via the peristaltic pump, 200 ml of a solution prepared according to the procedure as outlined in Example I was added over a period of 4 hours. The obtained white suspension was subsequently refluxed for 2 hours. The slurry was cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen. A sample of the catalyst was used to determine the pore volume via a so called Mercury intrusion measurement. The pore volume was 0.87 cm.sup.3/g. The D.sub.50 of the catalyst was 5.1 m.

Example XXVI

Preparation of a Catalyst

(26) In a 0.8 liter glass reactor, equipped with a condensor, a stirrer, baffles and a peristaltic pump, 400 ml of hexanes were added. To this, 8.65 ml of SiCl.sub.4 (75.8 mmol) and 1.73 ml EADC (5.9 mmol) were added. The mixture was at ambient temperature when the stirrer rate was set at 1700 RPM. Via the peristaltic pump, 100 ml of a solution prepared according to the procedure as outlined Example I was added over a period of 2 hours and 40 min. The white suspension was subsequently refluxed for 2 hours. The slurry was cooled down to ambient temperature, filtered and washed 3 times with hexane. Finally the solids were taken up in hexane and stored under nitrogen. Catalyst concentration was determined at 15.9 mg/ml. A sample of this catalyst was used to determine the pore volume via a so called Mercury intrusion measurement. The pore volume was 1.01 cm.sup.3/g. The D.sub.50 of the catalyst was 5.0 m.

Example XXVII

Polymerization in the Presence of the Catalyst According to Example XXVI

(27) The polymerization experiment was performed in a 10 liter steel autoclave using 5 liter of a 1.5 millimolar solution Al(C.sub.2H.sub.5).sub.3 in purified hexanes as a diluent. The mixture was heated to 60 C. and pressurized with 6 bars of ethylene.

(28) Subsequently 6.3 ml slurry containing in total 100 mg of the catalyst from Example XXVI was dosed to the reactor. Initially, the temperature was maintained at 60 C. and the ethylene pressure was kept constant at 6 bars by feeding ethylene. However, during the course of the experiment, the catalyst activity became very high and the temperature increased to above 60 C. Also the ethylene uptake by the catalyst became so fast that the consumed ethylene could not be compensated by the addition of fresh ethylene because the installed ethylene mass flow controller had reached its maximum capacity, causing the pressure to drop below 6 bars. Still the polymerization was maintained for 180 minutes. After work up of the polymer 4166 grams polyethylene with an average particle size of 160 m and a bulk density of 486 kg/m.sup.3 were obtained.

Example XXVIII

Polymerization in the Presence of the Catalyst According to Example XXVI

(29) Example XXVII was repeated after technical adjustments in the polymerization equipment by increasing the maximum capacity for the ethylene feed and the cooling capacity for the reactor. The temperature and ethylene pressure were maintained at 60 C. and 6 bars.
3177 grams of polyethylene having an average particle size of 153 m and a bulk density of 460 kg/m.sup.3 were produced in 180 minutes.