DE2340081C2 - Process for the preparation of disproportionation catalysts and their use - Google Patents

Description

20th

The invention relates to a method for producing \ •

of disproportionation catalysts and their

application for disproportionation of olefin carbon , ν

Hydrogen. 25 '^

Under the disproportionation of olefinically un- '

For the purposes of the invention, saturated hydrocarbon compounds is a reaction between two molecules ^or molecules

30 _x / ^R? Ri R ₃ \ /

R ₂ R ₄ 35

and between the remnants and

R ₅ R ₇ \ / ^R3

\ / 40 Γ

K ₆ K ₈

to understand. This reaction takes place by Aufbre- 45 ^Un

the double bonds between the residues "

K ₇

R ₁ \ /

50 / \

or

55 _R

K5

60 ^R 6

•
R ₂ . / and \ /
C.
/ \ C.
/ \. and C.
/ \
R ₄ between the leftovers Rs _n R ₆

This creates structures of the formula Ri R ₅

65 \ /

C = C

R ₃ C = C / C = C / R ₇ \ R ₄ Ri \ \ R ₈ R ₇

R ₂

R ₈

R ₃

C = C

R ₄

Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ , which are identical or different, can represent hydrogen atoms, alkyl radicals, mono- or polyolefinically unsaturated alkyl radicals, cycloalkyl radicals, mono- or polyolefinically unsaturated cycloalkyl radicals , Aryl radicals, alkaryl radicals, mono- or polyolefinically unsaturated alkaryl radicals, alkyl-substituted aryl radicals and aryl radicals which are substituted by mono- or polyolefinically unsaturated alkyl radicals. Either or both of the original olefin molecules can be a cyclic olefin. The following reaction types are mentioned as examples, all of which represent a disproportionation of olefinically unsaturated hydrocarbon compounds (hereinafter also referred to as olefins) within the scope of the invention:

a) Reaction of a molecule of a non-cyclic monoolefinically unsaturated compound with a same molecule forming monoolefins, which are higher and lower Have C number as the starting olefin.

b) Reaction of a molecule of an unsaturated compound that has two or more non-conjugated Contains double bonds (e.g. a polymeric compound) with a molecule like or another compound that contains two or more non-conjugated double bonds.

c) Reaction of a non-cyclic monoolefin with a non-cyclic monoolefin of a different composition forming two monoolefins, where the sum of the number of carbon atoms of these olefins is equal to the sum of the number of carbon atoms in the original olefins.

d) Reaction of a non-cyclic monoolefinically unsaturated compound with a polyolefinically unsaturated compound.

e) reaction of a non-cyclic monoolefin with a cyclic olefin. This reaction will a compound is formed that contains a number of carbon atoms equal to the sum of the number of the carbon atoms present in the cyclic and non-cyclic olefin.

0 reaction of a cyclic olefin with another cyclic olefin with the same or a different structure.

g) reaction of a cyclic olefin with a polyunsaturated olefinic compound. at

This reaction forms a compound that contains the sum of the carbon atoms and double bonds that were present in the reactants.
10

In GB-PS 10 54 864 a process for the disproportionation of acyclic olefins is carried out Combining the olefin with a catalyst consisting of rhenium heptoxide on alumina as the catalyst exists, described.

AuiderGB-PS 12 16 587 is a process for the disproportionation of olefins by combining of olefins with an alumina-containing disproportionation catalyst under conditions among which the feed is disproportionated, are known. The alumina of this catalyst is been impregnated with phosphate ions before combining with the catalyst. The impregnation is a common method of applying an active component to a support. Basically This method consists in treating the carrier with a solution of a compound or a salt treated and the excess solvent is usually removed by evaporation and thereby the catalyst dries. The desired catalytic material is thereby forced into all pores penetrate and / or extend over the surface of the carrier, whereby it is completely out of solution is transferred to the carrier.

In this known method, drying the catalyst is thus an indispensable measure which can in no case be waived. In addition, the impregnation is not very selective and not entirely satisfactory with regard to the incorporation of the catalytic material within the support.

The invention is based on the object of making available a method that provides better penetration of the carrier with the catalytic material is ensured and its selective incorporation is preferred at specific points on the support, in order to obtain catalysts in this way, where not only a larger amount of rhenium heptoxide can be applied, but at the same time the activity the catalysts is increased.

The solution to this problem is a process for the production of disproportionation catalysts which 1 contain up to 15 wt .-% rhenium heptoxide on an aluminum oxide treated with phosphate ions, the is characterized in that the aluminum oxide prior to application of the rhenium heptoxide with an aqueous ammonium phosphate solution at temperatures between ambient temperature and the boiling point the ammonium phosphate solution digested, then separated from the solution, washed and dried and calcined.

To digest, the carrier is immersed in a solution of the salt, whereupon the excess solvent and removing the solute, for example, by washing. At no point do you let that Carrier dry or uncovered so that it is always in equilibrium with the excess of the external solution is. It is assumed that here a preferred incorporation of the solute only on specific

Positions within the carrier, so more selective than with the Impregnation takes place.

Ammonium phosphate itself and ammonium dihydrogen phosphate are suitable as ammonium phosphate for the purposes of the invention and diammonium hydrogen phosphate, with diammonium hydrogen phosphate being preferred.

As aluminum oxide, aluminum oxide is preferred which is obtained by hydrolysis of aluminum alkoxides obtained boehmite is produced. The aluminum alkoxides are produced by oxidation of the products obtained from a Ziegler reaction of a low molecular weight aluminum alkyl with an δ ^ monoolefin.

Rhenium heptoxide can be applied to the modified support by any known method will. For example, the processes described in GB-PS 11 05 563 and 11 05 564 are suitable, however, the modified carrier is preferably treated with an aqueous solution of rhenium heptoxide or a rhenium compound capable of forming rhenium heptoxide, impregnated and then dried. Suitable rhenium compounds that can be decomposed to rhenium heptoxide by heat are for example ammonium perrhenate and perrhenic acid.

The ammonium phosphate can be used in the digestion in such an amount that an aluminum oxide, which contains up to 16%, preferably up to 12%, in particular up to 8% phosphate ion will. As mentioned, digestion takes place at temperatures between ambient temperature and the boiling point the aqueous ammonium phosphate solution, preferably at temperatures between 40 ° C and the Boiling point carried out. Elevated pressure can be used, but digestion will be done at normal pressure preferred.

In a modified embodiment of the method according to the invention, the aluminum oxide can before digesting with the aqueous ammonium phosphate solution with an aqueous aluminum nitrate solution be digested.

The duration of digestion with the aqueous ammonium phosphate depends on a number of factors, namely on the temperature, the concentration of the ammonium phosphate solution and the required Degree of deposition of the phosphate ion. The digestion is expediently 0.5 to 24 hours, preferably 1 to 12 hours, especially 1 to 6 hours. The treated alumina can then be used separated by sieving of digesting agent and is then washed, dried and calcined

The catalyst can preferably contain 1 to 12% by weight of rhenium heptoxide, with a content of 1 up to 10% by weight is particularly preferred.

The use of the catalyst prepared according to the invention for the disproportionation of olefin hydrocarbons takes place expediently so that the olefin hydrocarbons or their mixtures in one Temperature in the range from -20 ° to + 500 ° C and a pressure in the range from 0 to 140 bar with an in the disproportionation catalyst prepared in the manner described above.

Olefin hydrocarbons suitable as starting materials are, for example, acyclic C ₂ -C ₃₀ olefins, preferably straight-chain Q 1 -C _g alkenes. Suitable alkenes are, for example, ethylene, propylene, butene-1, butene-2, pentene-1, pentene-2, hexene-1, hexene-2, hexene-3, heptene-1, heptene-2 and heptene-3. Branched Cj-Cj _u alkenes are also suitable as starting material. A starting material which contains 2-butene and isobutene is preferred.

The reaction conditions differ depending on the composition of the starting material, the desired product and the type of catalyst. The catalyst is preferably activated before it comes into contact with the orofin hydrocarbon. This takes place advantageously by heating in flowing air or flowing oxygen at a temperature in the range of 400 ° to 800 ⁰ C for a time of 0.5 to 48 hours.

The reaction temperature is preferably in the range of 20 ° to 100 ⁰ C. The disproportionation may be operated batchwise or continuously, using the catalyst as a fixed bed, fluidized bed or moving bed are performed. The reaction can take place in the gas phase or liquid phase, but it is preferred to work in the liquid phase.

The reaction time is between 0.01 seconds and 120 minutes, preferably between 0.1 seconds and 10 mins.

In the batchwise disproportionation, the weight ratio of olefin to Catalyst range from 1000: 1 to 1: 1.

In the case of continuous disproportionation, the air velocity in space when working in of the liquid phase in the range from 1 to 100, preferably in the range from 5 to 20. When in the gas phase is being worked, it can be 500 to 10,000 V / V / hour. preferably in the range from 2000 to 6000 V / V / h lies.

The disproportionation can, if appropriate, be carried out in the presence of an inert diluent will. Examples of suitable diluents are paraffinic and cycloparaffinic hydrocarbons.

The products of the disproportionation can be broken down into fractions. Selected political groups, z. B. unreacted feed or fractions that do not have the desired carbon number, can be fed back into the process.

example 1

50 g of boehmite alumina having a particle size of 0.25 to 0.5 mm were calcined at 580 ⁰ C and allowed to cool. The granules were digested for 2 hours in 200 ml of an aqueous solution containing 30 g of aluminum nitrate near the boiling point of the solution. Water was added as needed to keep the granules covered. The mixture was then left to cool and allowed to settle. The supernatant liquid was decanted and replaced with 200 ml of an aqueous solution containing 3.1 g of diammonium hydrogen phosphate. The pellets were digested in this solution for 4 hours at 50 ⁰ C. The obtained slurry was poured into a sieve with a mesh size of 0.21 mm and washed with distilled water to separate the treated granules. The granulate was ^{dried overnight at 100 °} C. and then calcined for 8 hours at 500 ^° C. in flowing air.

20 g of granules were then impregnated with an aqueous solution of 1.34 g of ammonium perrhenate, evaporated to dryness, ^{dried in an oven at 110 °} C. and in flowing air for 16 hours

activated. The catalyst prepared in this way contained 5.9% Re ₂ O ₇ and 1.9% phosphate ion.

A commercially available butene (the typical composition of which is given in Table 1) based on the in the manner described in GB-PS 11 70 498 had been selectively hydrogenated and purified, was at room temperature passed over 10 ml of the catalyst contained in a steel reactor. The products were in analyzed for propylene and 2-methylbutene-2 at regular intervals. The results are in Table 2 called.

Table 1

Composition of the starting material

Wt%

Ethylene

propane

Propene

Butene-1

Isobutene

Butene-2

Butane

Table 2

Dismutation of the butenes

traces

traces

traces

6.6

48.6

35.2

9.6
100.0

Methylbutene-2 plus propylene is shown graphically as a function of the running time in hours. The representation shows that the catalyst produced by the process according to the invention is approximately double Activity of the usual rhenium heptoxide / aluminum oxide catalyst although the amount of rhenium heptoxide in the catalyst did not increase very much is.

ίο Example 2

10 g of the catalyst used in the experiment described in Example 1 were used for 24 hours 58O ° C reactivated. A butene with a similar composition as in Example 1, the mixture was passed over the catalyst for 7 days. During this time the reactor temperature was at a rate of 9 ° C / day from room temperature to the final temperature of 88 ° C elevated.

The butene conversion was 37% at the beginning. An initial yield of 115 g isoamylenes / 100 g catalyst / hour has been reached. During the test period of 7 days, the conversion and the yield fell to 23% to 64 g isoamylenes / 100 g catalyst / hour.

The average conversion (7 days) was 28.6% and the overall yield (7 days) was 144 g of C _s olefins / g of catalyst. A typical composition of the product is given in Table 3.

Table 3

Typical product composition in% by weight

Running time, hours

2-methylbutene-2 and propylene,%

5.9% Re ₂ O ₇ 4.97% Re, O ₇

+ 1.9% PO4-

30.7 17.8

33

32.7 16.5

29.8 14.4
27.6

25.8

Comparative experiment 1

Ethylene
Propylene

2-methylbutene-1

Pentene-2 (trans)

Penten-2 (ice)

2-methylbutene-2
> Cs hydrocarbons

50 g of boehmite aluminum oxide with a particle size of 0.25 to 0.5 mm were calcined at 580 ° C. and allowed to cool. 20 g of granules were then impregnated with an aqueous solution of 1.34 g of ammonium perrhenate, evaporated to dryness, ^{dried in an oven at 110 °} C. and activated in flowing air for 16 hours. The catalyst prepared in this way contained 4.97% Re ₂ O ₇ .

The catalyst was used for the disproportionation of the butene mentioned in Example 2 among the same Conditions used. The results of the analysis for propylene and 2-methylbutene-2 in the products are listed in Table 2.

The results of the comparative experiment and the experiment described in Example 1 are carried out further the figure illustrates in which the content of 2-

0.38

38.74

2.26

2.63

0.75

51.94

3.30

This example shows that the catalyst prepared by the process according to the invention also after a regeneration and a period of use of 7 days a higher activity for the disproportionation of olefins than the freshly made common rhenium heptoxide / alumina catalyst.

Comparative experiment 2

50 g of boehmite alumina having a particle size of 0.25 to 0.5 mm 24 hours, calcined at 580 ⁰ C and then impregnated with a solution of 0.93 g of diammonium hydrogen phosphate in 100 ml water. The mixture was evaporated to dryness and the granules obtained were heated at 200 ° C. for one hour. The granules were then calcined for 20 hours at 580 ^° C. and then sieved in such a way that granules of 0.25 to 0.5 mm, free of fines, were obtained.

46.8 g of the granules were impregnated with an aqueous solution of 3.14 g ammonium perrhenate, evaporated to dryness and dried at 100 ⁰ C. The catalyst was then activated, tested and analyzed in air at 580 ° C. It contained 4.75% Re ₂ O ₇ and 1.3% PO ₄ (= 1.0% P ₂ O ₅ ). The catalyst was used for the disproportionation of the butene used in the experiment described in Example 1 under the same conditions. The results are in the

Graph as% 2-methylbutene-2 + propylene as a function of the running time in hours shown.

Comparative experiment 3

The catalyst was prepared in the manner described in the preceding example, but was impregnated with 4.65 g of diammonium hydrogen phosphate, and 48.8 g of the phosphate impregnated granu- ι ο late were then impregnated with 3.27 g of ammonium perrhenate, one Catalyst was obtained which contained 4.23% Re ₂ O ₇ and 6.1% PO ₄ (= 4.6% P ₂ O ₅ ).

The catalyst was used for the disproportionation of the butene in Example! 1 composition mentioned used under the same conditions. The results are shown in the figure as% 2-methylbutene-2 + Propylene shown graphically in hours as a function of the running time.

Comparative experiments 2 and 3 show that the activity of the catalysts produced by impregnation is not as high as the activity of the catalysts prepared by digestion.

25th

1 sheet of drawings

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45

50

55

P.

65

Claims (2)

and claims: R7 1. A process for the preparation of disproportionation \ / approximately catalysts containing 1 wt .-% rhenium 15 bis 5 heptoxide q contained on a treated with phosphate ions / alumina N., characterized characterized marked r, that the alumina prior to applying the Rhenium heptoxide digested with an aqueous ammonium phosphate solution at temperatures io with simultaneous formation of double bonds between ambient temperature and the boiling point of the ammonium phosphate solution, then separated from the solution, washed, R ₁ dries and calcined. \ / 2. Use of a catalyst according to Claim 1 for the disproportionation of olefin carbons / hydrogen. η