DE1520882C - Process for the polymerization of alpha-olefins - Google Patents

Description

The invention relates to a process for the polymerization of -olefins in the presence of organic solvents at temperatures below 210 ^° C. and pressures below 200 atm using a supported catalyst; it is produced by impregnating the carrier materials silicon dioxide or its mixtures with aluminum oxide with chromium salts and activating it by heating in the presence of inert gases, oxygen or gases containing oxygen.

The method of the invention is characterized in that the catalyst prior to its activation by treating the carrier material with chromium fluoride has been received.

For activating the catalyst is preferably heated to temperatures between 300 and 900 ⁰ C, heated mainly between 400 and 600 ⁰ C. Depending on the olefin that is to be polymerized and the properties of the desired polymer, the duration of the activation can be changed to a large extent. Good results are obtained with activation times under 24 hours. The best results are achieved if ί is activated for up to 5 hours.

To carry out the polymerization, solvents or diluents are used for the monomers and the polymer formed are inert and furthermore dissolve the polymer. Suitable Solvents are aliphatic and cycloaliphatic hydrocarbons, such as propane, butane, isobutane, n-pentane, n-heptane, isooctane, cyclohexane and the like.

The process is carried out at pressures sufficient to produce the solution or solution used Diluent to liquid at the predetermined temperature conditions for the polymerization keep and the «-olefins in-the solvent or diluent to be dissolved in amounts which are sufficient for a satisfactory course of the polymerization.

After the end of the polymerization, the catalyst is separated off from the polymer and passed through Heating reactivated in the presence of oxygen or air.

The use of the catalyst treated according to the invention leads to very high yields of polymer of a high degree of crystallinity, such as Until now, they could only be obtained by using supported catalysts, which previously also had chromium oxides contained, but not treated with said chromyl halides before their activation had been.

This has been found in tests. In these the method according to the invention with method compared according to the known state of the art (Belgian patents 530 617 and 535 082), in which the catalysts produced in the various ways described are used became.

The preparation of the various catalysts is described below:

Catalyst A (according to the invention)

Micro-spherical silica-alumina (from Ketjen) with 87 percent by weight silica and 13 weight percent alumina was placed in a stainless steel reaction vessel. Through the reaction vessel, a stream became a gaseous mixture of nitrogen and chromyl fluoride passed to the silica-alumina to keep in the state of a fluidized bed.

The whole, passed through the reaction vessel

Chromyl fluoride reacted with the silica-alumina, so that the gaseous leaving the reaction vessel. Electricity contained neither fluorine nor chromium. The gas flow into the reaction vessel was interrupted after 30 minutes. An analysis of the catalyst obtained in this way gave: 1.16 percent by weight Chromium and 0.89 weight percent fluorine.

Catalyst B (according to the state of the art)

The same silica-alumina used for the preparation of the catalyst A was _{impregnated with an aqueous solution of CrO 3} in such an amount that it was completely absorbed by the solid mass.

After drying at 110 ^° C. in an oven under vacuum for 24 hours, a catalyst with 1.20 percent by weight of chromium was obtained. The catalysts A and B were activated under the same conditions in a stream of dry air at 500 ° C. for 2 hours and then in a nitrogen atmosphere until they were used

as held.

The two catalysts working under the same conditions were compared in the polymerization of ethylene. A 2000 ml stainless steel autoclave, equipped with a central stirrer and heating and cooling device, was filled to about one fifth of its volume with n-heptane and then ethylene was added up to 15 atmospheres. Then the catalyst (in an amount of 2 g per 100 ml of the solvent) was added; the temperature was increased to 140 ^° C. and the pressure to 40 atm by adding more ethylene.

These temperature and pressure conditions were maintained during the polymerization experiment.

One hour after the start of the polymerization reaction, the autoclave was emptied and the solvent was removed from the polymer obtained.

The results are summarized in the following table:

5 ° 1 Kata Amount of
^ k ■ * I ^ η 1fr ^ νΐ α ψ \ η ψ% • yield Yield on Ver 2 lysa
goal renewed
Polyethylene on total Chromium content in search
No. 3 G catalyst
based catalyst
based 4th A. 254 g / g g / g 55 5 A. 307- 31.8 2740 6th A. 305 38.4 3310 B. 140 37.2 3210 B. 192 18.7 1560 B. 155 23.0 1920 19.4 1620

The invention is illustrated by the following examples.

For example

The catalytic system was prepared in the following way: 10 g of well-dried chromic anhydride were placed in a stainless steel reaction vessel equipped with a gas inlet and a gas outlet pipe was provided.

A mixture of nitrogen and hydrogen fluoride was introduced through the inlet pipe; that

3 '...- ■ 4

by the reaction between hydrogen fluoride and placed in a 500 ml autoclave equipped with a

Chromic anhydride formed chromium oxyfluoride was provided in the middle arranged stirrer.

flows out of the reaction vessel and flows in. The ethylene was in the presence of this suspension

Passing through a CaCl ₂ -containing purification of the catalyst at a pressure of 36 atm and

column, in which it is freed from moisture, ^{polymerized in a 5 at 140 0} C 2 ¹ J ₂ hours,

second reaction vessel, the 30 g of silicon dioxide, 52 g of solid, white polyethylene were obtained.

Aluminum oxide with 87 ° / ₀ and 13% silica. .

Contains aluminum oxide. After 1 hour, the B e ι s ρ ι e 16

The introduction of HF was interrupted and the nitrogen replaced by 1.90 g of the catalyst prepared in Example 1

Oxygen replaced * and the silicon dioxide-Alu- 10 were 2 hours in the presence of dry air

The reactor containing miniumoxide was activated for 18 hours, then cooled and immersed in 250 ml of cyclohexane

200 ⁰ C heated. suspended. ·; .

2.40 g of the catalyst thus prepared were The suspension was placed in a 500 ml autoclave

Given 2 hours in the presence of dry air at 540 ° C, into which a little ethylene was then passed,

heated,. then cooled and placed in a 500 cc car 15 The autoclave was now heated to 137 ° C and

klav given, which contained 250 ecm of cyclohexane. The pressure was kept at 36 atm for 2 hours, whereupon

the autoclave was then introduced some ethylene, interrupted the introduction of the ethylene and the

the internal temperature was brought to 140 ° C, the autoclave was cooled and opened,

would. When the pressure in the autoclave fell, after removing the solvent and the catalyst

teres ethylene introduced. After a 2V ₂ StUHdIgCr reactor, 54 g of solid, white polyethylene were higher

The feed of ethylene was interrupted. Crystallinity was obtained as the reaction product.

^ and the autoclave is cooled. That in the autoclave.

j preserved reaction product consisted of white, öeispielv ._

solid polyethylene; the weight was 148 g. A catalyst was made by impregnating

. . j 25 about 50 g of silicon dioxide-aluminum oxide with 87%

Example 2 silica and 13% alumina with a

2.40 g of the catalyst prepared in Example 1 _; Solution of 2.33 g of chromyl fluoride in 100 ml of 1,1,2-tri

were 2 hours at 510 ° C in the presence of dry fiuortrichloräthan and subsequent "'evaporation

Air is heated, then cooled and in 250 ecm of cyclo- des unreacted chromyl fluoride and des

hexane suspended. The suspension of the catalyst 3 ° 1,1,2-trifluorotrichloroethane prepared

in cyclohexane was placed in a 500 ml autoclave. The catalyst prepared in this way contained 1.11%

given, into which some ethylene was then introduced. Chrome. -

The autoclave was then heated to 143 ° C. and 7 g of this catalyst were used for 2 hours

the pressure was held at 36 atm for 3 hours, whereupon 503 ° C activated in a stream of dry air,

interrupted the supply of ethylene and the 35 then suspended in 150 ml of n-heptane and

Autoclave was cooled and opened. in a 1000 ml stainless steel autoclave

After removing the solvent and adding a stirrer in the middle

Catalyst were 115 g of solid, white polyethylene. The autoclave was then heated to 140 ⁰ C

obtained high crystallinity as a reaction product. and with ethylene at a pressure of 40 atm

_. 40 loaded.

B e 1 s ρ 1 e 1 3 _After 1 hour the introduction of ethylene

1.46 g of the catalyst used in Example 2 uninterrupted and the autoclave cooled,

were in the presence of dry air for 2 hours. There were 115 g of solid polyethylene with high crystallinity

Heated to 520 ⁰ C, then cooled and preserved in an autoclave.

given, which contained 250 ml of cyclohexane. The poly 45 examples

merization of the ethylene was 2 ¹ J ₂ hours at 143 ⁰ C ■

and performed about 37 atm. 53 g of solid, white A catalyst was prepared by introducing a chrome

Polyethylene was obtained. mylfluoridhaltigen gas stream in a silicon dioxide

. Bed prepared, working as in Example 1

B 1 e s 1 e ρ 1 _5o 4 ^^ _The catalyst _thus prepared contained 1.2 ° / ₀

3.20 g of a cata-chromium produced according to Example 1.

lysators were in the presence of dry air for 2 hours 7 g of this 2 hours at 500 ⁰ C in a dry

the heated to 500 ⁰ C. Air flow activated catalyst were in 150 ml

After cooling, this was suspended in a 1-1 n-heptane autoclave. The suspension of the cat

given, which contained 500 ml of cyclohexane. The autoclave in n-heptane was placed in a 1000 ml autoclave

klav was now heated to 145 ° C and added with a little stirrer, into which ethylene then passed

Ethylene charged at a pressure of 40 atm. would. The autoclave was then heated to 150 ⁰ C

After 2 hours, the introduction of ethylene and the pressure were kept at 40 atm for 1 hour, whereupon

interrupted and the autoclave cooled. On this 5 g of highly crystalline polyethylene were obtained ..

Wise were 80 g of solid, white polyethylene high 60. .

Preserve crystallinity. for game y

. A catalyst would be created by introducing a

Example 5 mylfluoridhaltigen gas stream in a silicon dioxide

A catalyst based on chromium oxide aluminum oxide bed with a 87 ° / ₀ silica and

was produced as in Example 1. It contained 1.50% 65 13 ° / ₀ of alumina according to the method of

Chrome. This catalyst was prepared in Example 1 cyclohexane.

suspended, with a concentration of 10 g of this 2.53% chromium-containing catalyst

0.7 g per 100 ml of cyclohexane; the suspension was lysators were in a stream of dry nitrogen

Activated 2 ¹ Ii hours at 350 ^° C., then cooled (still in a stream of nitrogen) and suspended in 150 ml of n-heptane. The suspension of the catalyst in n-heptane was placed in a 1000 ml autoclave with a stirrer, which had previously been flushed out with nitrogen.

The autoclave was then ^{heated to 150 °} C. and at the same time charged with ethylene at a pressure of 40 atm. The autoclave was kept for 1 hour at 15O ⁰ C and 40 atm and is then cooled and opened. After removing the solvent, 120 g of a solid, white polymer were obtained which consisted of linear polyethylene.

B e i s ρ i e 1 10

30 g of silica-alumina were placed in a reactor suitable for the fluidized bed process given with 87% silica and 13% alumina. Through . this silica-alumina bed a stick stream containing chromyl fluoride was passed through for 1 hour. In this way a catalyst was obtained with 1.98% chromium deposited on the silica-alumina. .

11g of this catalyst were activated ^{2 1} ^ StUHdCn in a stream of dry air at 500 ^{0 C,.} cooled and placed in a 1000 ml autoclave equipped with a stirrer, which contained 200 ml n-heptane ..

Propylene was polymerized in this autoclave at 95 ^° C. and 35 atm for 2 hours. 9.8 g of a polymer were obtained, of which 9.1 g were soluble in n-heptane and 0.3 g insoluble in pentane but soluble in boiling n-heptane and 0.4 g insoluble in boiling n-heptane.

Example 11

35

11.2 g of a catalyst prepared according to Example 1 with 1.34 weight percent chromium were used as a fluidized bed in a stream of oxygen for 3 hours heated to 560 ° C.

After cooling in a stream of nitrogen, the catalyst was suspended in 150 ml of iso-octane and placed in a 1000 ml Aiitoklav, into which 150 ml of 1-hexene were also introduced. The temperature was now increased to 120 ^° C. and held that way for 4 hours. The autoclave was then ventilated, and after the solvent and the unreacted 1-hexene had been distilled off, 21 g of an oily-looking polyhexene were obtained.

B e i s ρ i e 1 12

2.3 g of the catalyst prepared according to Example 1 with 1.16 weight percent chromium were vacuum heat treated 24 hours, after which it was heated for 2 hours at 540 ⁰ C in the fluidized bed in a trokkenen airflow. The resulting catalyst contained 1.55 percent by weight fluorine.

After cooling in a stream of nitrogen, the catalyst was suspended in 150 ml of n-heptane and placed in a 1000 ml autoclave.

In the same autoclave and ethylene was atm at a pressure of about 15 while increasing the temperature to 140 ⁰ C initiated. The pressure was raised to 40 atm, where it was maintained throughout the reaction, while the temperature reached a maximum of 176 ⁰ C by the addition of slightly more ethylene. After 1 hour the autoclave was opened and 215 g of polyethylene were obtained.

Example 13

2.7 g of the catalyst prepared according to Example 1 with 0.78 percent by weight of chromium and 1.59 percent by weight of fluorine were in a fluidized bed in a dry air stream. Heated to 540 ^° C. for 2 hours.

After Abkühlefi ^ of "· catalyst in a stream of nitrogen, the catalyst was suspended in 300 ml n-heptane and placed in a 1000-mL autoclave was introduced atm in the ethylene at a pressure of 15, while the temperature is increased to 160 ⁰ C. would.

By introducing a little more ethylene, the pressure was increased to 40 atm, where it remained during the entire reaction was held. After 1 hour the autoclave was opened, with 124 g of polyethylene were obtained.

Example 14

8.2 g of the catalyst prepared according to Example 1 with 1.10 weight percent chromium and 1.09 weight percent fluoride were heated in the fluidized bed 2-Stundeiu to 520 ⁰ C in a dry air stream. After cooling "of the catalyst in a stream of nitrogen, the catalyst in 150 ml of n-heptane was suspended and placed in a 1000-mL autoclave was introduced atm in the ethylene at a pressure of about 15, while the temperature was raised to 140 ⁰ C . ■

By introducing more ethylene, the pressure was increased to 38 atm, at which it was during the entire reaction was held. One hour after the start of the reaction, the autoclave became opened, whereby 251 g of polyethylene were obtained.

According to the X-ray analysis, the polyethylene obtained showed a crystallinity of 78%.

The inherent viscosity of these polymers, measured in a solution of decahydronaphthalene at 135 ° C, was 1.65. After the I.R. investigation, the polyethylene was found to be straight-chain and without any branching.

Claims (2)

Patent claims: 1. Process for the polymerization of -olefins in the presence of organic solvents at temperatures below 210 ^° C. and pressures below 200 atm using a catalyst, produced by impregnating the carrier materials silicon dioxide or its mixtures with aluminum oxide with chromium salts and activating by heating in the presence of inert ones Gases or oxygen-containing gases as well as oxygen itself, characterized in that the catalyst was obtained before its activation by treating the support material with chromyl fluoride. 2. The method according to claim 1, characterized in that the catalyst ^{is activated by heating to temperatures between 300 and 900 0} C, preferably between 400 and 600 ⁰ C, in the presence of inert gases, oxygen or oxygen-containing gases.