DE1520467B2 - PROCESS FOR THE POLYMERIZATION OF AETHYLENE - Google Patents

Description

1 2

It is already known to use olefins in the presence of The aluminum fluoride can before, after or equal to

Polymerize catalysts that are added by slowing down with the addition of the chromium compound

beat of chromium oxide (e.g. CrO ₃ ) or to become one as described more fully below

Chromium oxide calcinable chromium compound (e.g. will. The catalyst used according to the invention

Chromium (III) nitrate, chromium (III) sulfate, ammonium 5 can be obtained by heating the carrier, e.g. B. Silica

chromate or chromium carbonate) on a carrier, e.g. B. aluminum oxide, in the absence of chromium oxide and

Silica-alumina, and activation by in the presence of hydrated aluminum fluoride

Heating to elevated temperature, with at least one elevated temperature, precipitation of chro-

Part of the chromium, preferably at least 0.1 Geoxide on the mixture obtained and heating to

percent by weight, based on the total catalyst, to achieve the final activation

weight, remaining in the hexavalent form, produced the. Alternatively, the catalyst can be produced

have been. This type of activation process involves the precipitation of chromium oxide or one too

is often done by placing the dried chromium oxide on the support, e.g. B. Silica

Chromium oxide-silicon dioxide-aluminum oxide preparation Aluminum oxide, calcinable compound, dry

several hours to a temperature of 400 to 816 ° C - in the presence of water - and heating

is heated in such an atmosphere that that of the obtained chromium oxide-containing mixture on

Chromium oxide after heating at least partially in an elevated temperature in the presence of hydrating

hexavalent state is present. Usually it is preferred aluminum fluoride.

it is preferred that the heating be carried out in the presence of an acidic substance-containing gas, such as air, is carried out. However, the silica-alumina or another can the atmosphere is also composed of nitrogen or one of the aforesaid carriers, a hydrated aluminum other inert gas. Alternatively, fluoride and chromium oxide (or one to chromium oxide the heating can be carried out in a vacuum. Add calcinable chromium compound) and you can reducing gases are also present, heat the prepared mixture to an elevated temperature, provided that they are only present in amounts such that the desired degree of polymerisation is obtained not all of the hexavalent chromium reduced activity is achieved.

and something hexavalent in the finished catalyst - The heating of the support or the chromium oxide

all chromium remains. It is preferred, however, that the containing mixture is in the presence of hydrated

reducing gases are not present. The total aluminum fluoride should preferably be at a temperature

chromium content of the catalyst is generally in the 30 temperature range, which does not exceed ^{500 0 C, except}

in the range from 0.5 to 30 percent by weight, the heating time to such temperatures can be

but also lie outside this range. extremely short, e.g. B. 1 minute or less. Preferential

It is also already known that, molecularly, the temperature should be in the range from 400 to

weight of the poly-621 ⁰ C obtained with these catalysts. The heating is usually carried out during

Merisate can increase if one rend the wearer of a period of time in the range of 5 minutes

Catalyst with a fluoride, e.g. B. hydrogen fluoride, up to 20 hours or longer and preferably in that

heated (see Belgian patent 535 082). Range from 30 minutes to 10 hours.

It has now been found that, in the polymerization, the expression "hydrated aluminum fluoride" of ethylene with the catalysts mentioned includes the solid hydrates of aluminum fluoride, a considerable increase in the activity of the catalysts 40 and the aqueous solutions of aluminum fluoride. The amount of added hydrated aluminum fluoride catalyst with hydrated aluminum fluoride, minium fluoride is generally in the range of the Indian patent 535 082 not mentioned 0.1 to 8 percent by weight, based on the total, has been heated . catalyst weight. These values indicate the aluminum object of the invention is a process for 45 fluoride, based on an anhydrous basis, ie, polymerization of ethylene, alone or together the amount of added hydrated aluminum with other olefins, at temperatures of 38 to fluoride is sufficient in order to give the 260 ⁰ C with the help of catalysts, which by impregnating catalyst an aluminum fluoride content in the gnate or precipitation of chromium oxide or a range of 0.1 to 8 percent by weight before heating. Chromium oxide calcinable compound on silicon 5 ° The amount of aluminum dioxide, aluminum oxide, zirconium oxide or thomine fluoride added is preferably in the range from 0.5 to 7 percent by weight of rium oxide as a carrier and subsequent heating. Amounts of aluminum fluoride outside of that have been maintained, with at least a portion of the stated range, can be added. Chromium in the finished catalyst in hexavalent However, amounts below 0.1 percent by weight lead to the condition and the catalyst support being treated with a lower effect than in the other case realized fluoride, which can be identified by this, and amounts above 8 percent by weight It is shown that the carrier of the catalyst used does not cause enough additional activation to be heated to fluoride at least partially with hydrated aluminum, the additional consumption of aluminum fluoride. justify.

The results achieved according to the invention are as 60 The mono- or mixed polymerization according to the

surprising to look at. Due to the fact the method of the invention may be according to the person skilled in the art

that hydrogen fluoride an increase in molecular weight known processes are carried out. The mono-

caused, it could not be foreseen that ethylene could be the only one

hydrated aluminum fluoride consist of a considerable monomer if an ethylene homopoly-

Increased activity, d. H. an increase in the amount of merit is desired. If a copolymer

A maintained polymer yield per unit weight is desired, contains the monomer charge

added catalyst, leads, as by the next, in general, a main part of ethylene and one

the following examples are discussed below. lower proportion of an olefin with a higher

3 4

Molecular weight, such as ζ. B. propylene, 1-butene, 1-pen vessel, removal of the supernatant liquid

th, 1-hexene, 4-methyl-1-pentene, 1,3-butadiene or decanting, filtering and / or evaporation and

Isoprene. In many cases, the higher olefin is recovered in quantities of the polymer, which is thus from the process

less than 10 percent by weight based on the ready-to-use diluent. If the

Total olefins, present. 5 Reaction carried out at temperatures above 107 ° C

The reaction can be in the gas phase, in the liquid phase, the polymer is usually at least partially

or in a mixed gas-liquid phase as a solution in the diluent. Under

be guided. It is often desirable that the reaction mixture can be affected by these circumstances

to use thinners, since the thermal ones are drawn off the reaction vessel, not the other way around.

Effects of the polymerization reaction in the presence of olefin is removed, e.g. B. by evaporation,

a liquid diluent, the catalyst is more easily condensed by filtration or centrifugation.

are trollable. The diluent can be removed and the polymer is removed from the any yaw

Be a hydrocarbon that is chemically inert and when dissolved in the diluent by cooling

the reaction conditions on the catalyst is not isolated, the polymer precipitating and then

has a harmful effect. In general, the diluent is used to filter or use the diluent

Medium paraffins or cycloparaffins with 3 to is evaporated.

12 carbon atoms per molecule applied. When performing the method of the invention Games for suitable diluents are propane, other reaction techniques and isolation isobutane, η-butane, isopentane, n-pentane, the isohexanes, processes known to those skilled in the art, including hexane, the isooctanes, the dodecanes, cyclopentane, 20 are applied.

Methylcyclopentane, cyclohexane, methylcyclohexane The drawing illustrates various embodiments the dimethylcyclohexanes. There can be aromatic forms of the process of the invention as well as the Her hydrocarbons with 6 to 12 carbon atoms position of the catalyst.

can be applied per molecule. However, these seem as shown in the drawing, the cataly-

Hydrocarbons or the impurities that they 25 satorträger, z. B. silica-alumina, from

usually accompany the catalyst something taken to source 2. The carrier is hydrated

deactivate, and they are therefore often not given to preferred aluminum fluoride from source 3. That

admitted. However, it is quite possible for such aro-fluoride to be passed through line 4 and intimately with it

matic hydrocarbons, such as benzene and toluene, mixed with silica-alumina. the

Xylenes or ethylbenzene to use. When the 30 obtained mixture is then transferred to the heating zone 6

If a diluent is used, it is generally stated. In the heating zone 6 the mixture is

mean present in sufficient quantity so that the heated to elevated temperature, and not above

Olefin concentration in total hydrocarbons - 649 ° C as previously stated. To the received

Stock loading on the order of 0.5 to mix will chromium trioxide from source 7 and above

10 percent by weight, although these limits are not given, line 8 and the resulting mixture lengthways

are absolute. the line 9 led into the activation zone 10.

As a catalyst contacting technique, ir- Of course, others can also use the chromium oxide cal-

any of the known techniques can be used. cinable chromium compounds instead of chromium

Thus the reaction can be carried out using trioxide. In the activation zone 10

the hydrocarbon charge with a catalyst 40 the chromium oxide-containing mixture is heated, preferably

Satorfestbett is contacted, with a catalyst way in the presence of free oxygen, and im

Gravitational bed or by contacting with the essential in the absence of water on elevated

Catalyst, which is in the form of finely divided particles in the temperatures up to about 635 ° C, preferably on

Diluent is suspended and the sus- 400 to 593 ° C brought to the catalyst

pension is maintained by stirring, or to give maximum polymerization activity and

by using the fluidized bed technique. him for use in the polymerization reaction

The polymerization takes place at a temperature in which to finish.

In the above process, the aluminum temperature can be in the range of 66 to 177 ° C. The fluoride and / or the chromium trioxide either in solid form aqueous solution are added. Atmospheric pressure up to a multiple of When the compound is added as an aqueous solution 70.3 kg / cm ² . Is when using a liquid encryption, agrees with the addition of preferably an dünnungsmittels it is generally desirable drying step at temperatures up to about 150 ⁰ C, the reaction vessel under sufficient pressure to shark, before heated to higher temperatures or aktiten, by the diluent in substantially 55 fourth.

to keep the liquid phase. Pressures in the order of magnitude

_α of 3.52 to 49.2 kg / cm ² are generally passed through lines 8, 8 'and 4 for this chromium trioxide

_n purpose suitable. and together with the hydrating AIu-

The residence time or reaction time in the minium fluoride can be the silica-alumina

_n range from a few minutes to several hours 60 can be added. The mixture obtained is then

_n i lie and is generally in the region of passed through line 5 into the heating zone 6. at

[_ i 15 minutes to 3 hours. Implementation of this alternative embodiment

_n ^: If the reaction takes place at temperatures of around the heating zone 6 and the activation

107 ° C and below, the zone 10 being merged into a single zone,

_lt forming polymer or copolymer in form 65 because the high-temperature fluoride treatment and the

\ _σ a solid granulate suspension in the reaction activation to ensure the presence of

.p mixture is present, the polymer can at the same time through de-hexavalent chromium in the catalyst

. _n ■ removal of the reaction mixture from the reaction can be carried out. As previously stated,

5 6

when the chromium trioxide and the aluminum polymer, heating the remaining poly-

fluoride as one or more aqueous solutions added merisats, preferably at a low temperature,

will give to volatilize the solvent adhering to such a solution and

Gnated silica-alumina, preferably the insulation of the polymer include. At this

before heating to higher temperatures, at temperature, the catalyst removal can be carried out in

dried temperatures which do not exceed 15O ⁰ C. may be omitted in some cases. The Concentrations

In another alternative embodiment, tration of the catalyst in the reaction mixture, the chromium oxide is generally passed through lines 8, 8 'and 4 of the polymerization zone 12, with the silicon dioxide-aluminum oxide provided up to 0.1 percent by weight or below, and the mixture obtained without the 10% by weight or above. When the cata- aluminum fluoride is passed through line 5. After satorkonzentration is low, z. B. 0.1 weight prodem heating the mixture of chromium oxide and cent or less, and the polymerization under silica-alumina, preferably to 107 ⁰ C, as described above, is carried out, temperatures in the range of 400 to 704 ⁰ C and the Polymer with a productivity in the size preferably in the presence of essentially 15 order of several thousand kg of polymer per anhydrous oxygen-containing gas, the hydra- kg catalyst will be generated so that the catalyst tized aluminum fluoride through the lines 4 and in the finished polymer in concentrations of 4 'and the chromium oxide-silicon dioxide-aluminum is less than 0.1 percent by weight present and added in a miniumoxide mixture. 'In many cases it no longer has to be removed.

This mixture is then passed through line 9 20
and in zone 10 of a final activation stage
at temperatures not exceeding 635 ° C as indicated above. This heat treatment or ice ρ ie 1 1
Activation also takes place preferably in the presence of an oxygen-containing gas and under Elimi- 25

nation of any water of hydration formed from a catalyst was prepared by Imprädem system. Heating is continued in order to ensure the gnieren of a silica-alumina gel presence of hexavalent chromium in the ferti- (about 90 weight percent silicon dioxide and 10 counter catalyst, and is done preferably weight percent aluminum oxide) with an aqueous way in the presence of an oxygen-containing gas , 30 solution of chromium trioxide, drying is substantially free of water at about 15O ⁰ C. A flow of and activation by heating in the presence of such gas, which is passed over or through the catalyst, substantially anhydrous air (dew point below during heating, serves to de- -17.8 ° C) for about 5 hours at 538 ° C. Removal of any water of hydration formed. During this treatment, the catalyst was in shape

The activated catalyst is held through line 11 35 of a fluidized bed with the aid of a

passed into the polymerization zone 12. A carbon-applied air flow.

Hydrogen diluent according to the above In approach 1 (comparative experiment) of the following

Discharge is drawn from source 13 through line 14 - Table I became the catalyst as described above

leads. The ethylene is used either alone or without further treatment.

Mixture with a relatively small amount of a 40 In batch 2, the silicon dioxide-aluminum

copolymerizable other olefins, such as. B. oxide mixed with hydrated aluminum fluoride,

1-butene, supplied from source 16 through line 17. Heated to 538 ° C. for 5 hours, then with the aqueous

After a suitable residence time in zone 12, impregnated under chromium trioxide and, as described above,

Activated polymerization conditions according to the above indications in dry air.

ben is the reaction mixture through line 18 45 In batch 3, the silicon dioxide-aluminum

removed and led to zone 19 for insulation; oxide impregnated with an aqueous solution of

Unreacted monomer is replaced by the lei- chromium trioxide and hydrated aluminum fluoride

device 20 returned. Isolated diluent (61% aluminum fluoride, 39 weight percent H ₂ O)

is returned through line 21. The catalyst and then dried and - as above

Sator can be written from the system through line 22 50 - activated in air.

removed. That as. Polymer obtained product In batch 4, the silicon dioxide-aluminum becomes taken via the outlet 23. oxide with solid chromium trioxide and solid hydrated

In one embodiment, the isolating aluminum fluoride can be mixed and the obtained

zone 19 the steps for evaporation or removal mixture was loaded in anhydrous air as above

of unreacted ethylene, filtering or writing, activated.

trifugation of the remaining polymer and In the two batches 2 and 3, the hydration was

diluent for the removal of suspended aluminum fluoride added in sufficient quantity

Chromium oxide catalyst and evaporation of the forgiving, with an A1F ₃ content of the catalyst of

thinning agent from the solution obtained to obtain 5 percent by weight before subsequent heating

treatment of purified or refined polymer than 60 was achieved.

Include backlog. Ethylene was with a suspension of each catalyst

In an alternative insulation system, especially in powdered form in n-pentane at a temperature

the other, if the polymerization reaction at a temperature of 102 ° C and a pressure of 31.6 kg / cm ²

Doors below 107 ° C is carried out with the solid contacted. The duration of each approach was 1.5 hours

Polymer in the polymerization zone as a suspension 65 den. The reaction was done in a closed

of granulated, non-sticky polymer is present, reaction vessel carried out with a mechanical

the isolation zone 19 may have the stages of the decannical stirrer. In any case

control of the diluent from the settled applied catalyst amount was about 0.1 Ge

percent by weight, based on pentane. The polymer was isolated by removing the contents of the reaction vessel and evaporation of n-pentane. All of that

Substances fed into the reaction vessel were essentially free of water. It became the following Results obtained:

Table I.

Yield, Density of the ■ Polymer approach kg polymer Polymer, melt index (b) No. per kg g / cm ³ catalyst 25 ° C (a) 0.39 1*) 1790 0.9555 0.55 2 4250 0.9558 0.41 3 3720 0.9549 0.29 4th 4390 0.9518

*) Comparison test.

(a) ASTM D 1505-57 T with the exception that the sample was conditioned prior to density determination Melting, heating to 150 ° C in a melting mold, Cool to 121 ° C at a rate of 11.1 to 16.1 ° C per minute by circulating water through the mold cooling system and then allowed to stand to cool to room temperature, without control the cooling rate.

(b) ASTM D 1238-57 T, condition F.

Example 2

The above data show that the various
Techniques described for treating the catalyst with hydrated aluminum fluoride have an effect. The approaches in this example were carried out as in the case of increasing the polymer yield example 1, unless otherwise stated. The results obtained are set out in Table II.

Table II
Cr content of each catalyst 25% by weight

approach
No. Weight
percent
AlF ₃ Method of
A1F ₃ addition Activation
temperature
'"C yield
kg / kg Polymer
melt index
(a) 5 *)
6th
7 *)
8th 0
2.5
4.8
4.8 Dry mixing with non-activated
Cr oxide catalyst
Cr oxide catalyst, activated at 538 ° C ver
mixes with hydrated AlF ₃ that separates
was calcined at 593 ° C
Catalyst as in batch 7, but subsequently
activated at. 538
, 538
538 2420
3570
2360
3570 0.71
. 0.63
0.90
1.00 (b)

*) Comparative tests.

(a) ASTM D-1238-57 T, Condition F.

(b) Condition Ε value, 0.01.

The above data show that the improvement can only be achieved if the catalyst after heated by the addition of hydrated aluminum fluoride.

Example 3

The approaches in this example were as in the example 1, approach 4 carried out, unless otherwise stated. The results are shown in Table III.

Table III

approach
No. 7oF
admitted Activation
temperature
° C yield
kg / kg Polymer
melt index
(a) 9 *) no 538 1370 10 1.7 538 2150 0.75 11th 3.4 538 2550 0.51 12 *) no 593 1850 1.56 13th 1.7 593 2890 1.08 14th 3.4 593 2870 -

*) Comparative tests,
(a) ASTM D 1238, condition F.

109 522/360

ίο

• The above data, the achievable by activation of the fluoride-containing catalyst at 538 and 593 ⁰ C show improvement.

By applying the same method as in Preparation 11, an olefin feed containing 95 weight percent ethylene and 5 weight percent can contain 1-butene, to form a copolymer having a density of about 0.95 g per cm ³ are copolymerized.

Eg game 4
The catalysts in the above batches were prepared by impregnating aluminum oxide or silicon dioxide with aqueous chromium trioxide, drying at 150 ° C. and mixing the hydrated aluminum fluoride (described in Example 1) as a powder with the dried chromium oxide-aluminum oxide or chromium oxide-silicon dioxide mixture . The mixture obtained was then, as described in Example 1, heated in dry air to 538 ° C. for 5 hours. The following values were found for ethylene

o receive polymerization batches as shown in the example 1, unless otherwise stated:

Table IV

approach
No. Basic catalyst %
Cr Reaction time,
hours yield
kg / kg Reaction
temperature
° C Enamel
indejj (a) 15 *)
16
17 *)
18th
19 *) Microspheroidal Alu
minium oxide
Microspheroidal Alu
minium oxide + 5 ° / ₀ AlF ₃ ..
Alumina gel powder ...
Alumina from approach
22+ 5% AlF ₃
Microspheroidal silicon
dioxide ■. 2.5
2.5
1.0
1.0
2.5
2.5 1.0
0.75
1.0
1.0
1.0
1.0 <5
6.4
11.9
27.0
.139 ^:
803 141 to 143
141 to 143
141 to 143
141 to 143
141
143 0.15
0.60 20th Microspheroidal silicon ^
dioxide + 5 ° / ₀ AlF ₃

*) Comparative tests.

(a) ASTM D 1238-57 «/ ο, condition E.

The above data show that the improvement cannot only be achieved when the catalyst support is silica-alumina is, but also when aluminum or silicon dioxide are used as a carrier. A similar improvement is achieved when zirconium oxide or thorium oxide is used as a carrier.

Claims (5)

Patent claims: 1. Process for the polymerization of ethylene, alone or together with other olefins, at Temperatures from 38 to 260 ° C with the help of catalysts, which by impregnation or precipitation, of chromium oxide or a compound that can be calcined to form chromium oxide on silicon dioxide, Aluminum oxide, zirconium oxide or thorium oxide as a carrier and subsequent heating with at least some of the chromium in the finished catalyst being hexavalent Condition, is present and the catalyst support has been treated with a fluoride, characterized in that the support of the catalyst used is at least partially has been heated with hydrated aluminum fluoride. 2. The method according to claim 1, characterized in that the carrier with the hydrated Aluminum fluoride has been heated prior to the precipitation of the chromium oxide on the support. 3. The method according to claim 1, characterized in that the chromium oxide carrier mixture has been heated with the hydrated aluminum fluoride. 4. The method according to claim 1, characterized in that the carrier, the hydrated aluminum fluoride and the chromium oxide or the compound which can be calcined to form chromium oxide have been mixed with one another and heated. 5. The method according to any one of the preceding claims, characterized in that the hydrated aluminum fluoride in an amount of 0.1 to 8 percent by weight based on the Total catalyst weight, has been used. 1 sheet of drawings