CH615900A5 - Process for the preparation of acrylic acid and methacrylic acid from the corresponding aldehydes - Google Patents

Description

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PATENT CLAIMS

1. A process for the preparation of acrylic acid or methacrylic acid from acrolein or methacrolein and molecular oxygen at a temperature of 200 to 600 ° C in the presence of a catalyst, characterized in that a catalyst is used which essentially comprises tungsten, phosphorus, vanadium, Contains molybdenum and oxygen and the formula

WaPbVcMo12Ox, where a and c 0.1 to 12, b is a positive number less than 6 and x is the number of oxygen atoms required by the valences of the other elements.

2. The method according to claim 1, characterized in that the reaction takes place in the presence of water vapor.

3. The method according to claim 1, characterized in that b is a number from 0.5 to 3.

4. The method according to claim 1, characterized in that the catalyst additionally contains antimony in a molar amount of 0.1 to 6.

5. The method according to claim 1, characterized in that one produces acrylic acid.

6. The method according to claim 1, characterized in that one produces methacrylic acid.

7. The method according to claim 1, characterized in that the catalyst additionally one or more of the elements tin, antimony, arsenic, copper, cerium, boron, chromium, iron, nickel, cobalt, uranium, manganese, silver, rubidium, rhodium, cadmium , Bismuth, indium, zinc or lanthanum.

Numerous catalysts are known for the oxidation of unsaturated aldehydes to the corresponding acids, see for example US Pat. No. 3,567,773. Although it is claimed in most cases that the catalysts are also useful for the oxidation of methacrolein to methacrylic acid, it has been found that the Yields of methacrylic acid are low and special catalysts are required for their production.

A process has now been found for the production of acrylic acid or methacrylic acid, in which acrolein or methacrolein is reacted with molecular oxygen at a temperature of 200 to 600 ° C. in the presence of a catalyst, if appropriate in the presence of steam. The process is characterized in that a catalyst is used which essentially contains tungsten, phosphorus, vanadium, molybdenum and oxygen and the formula

WaPbVcMo12Ox corresponds, where a and c 0.1 to 12, b is an integer less than 6 and x is the number of oxygen atoms, which results from the valence of the other elements. The catalyst can optionally additionally contain one or more of the elements tin, antimony, arsenic, copper, cerium, boron, chromium, iron, nickel, cobalt, uranium, manganese, silver, rubidium, rhodium, cadmium, bismuth, strontium, indium, zinc or contain lanthanum. The catalysts used in the process according to the invention provide high yields of methacrylic acid, in particular in a single pass, and are very stable under the required operating conditions.

The essential feature of the present inventive method is the catalyst. This catalyst is used here in the known process for the production of unsaturated acids from the corresponding aldehydes. Any catalyst corresponding to the above formula can be used. The catalyst can be produced by various processes which are generally known in the prior art and are explained in more detail in the present description.

In the preparation of the catalysts, for. B. the various catalyst elements combined, and the final product is usually dried at a temperature of 100 to 150 ° C. For some methods, calcining the catalyst at an elevated temperature of 300 to 600 ° C is recommended, but such calcination is usually not necessary. Numerous methods are known for combining the elements of the catalyst. The oxides of the elements can be calcined as a slurry and the resulting slurry is refluxed and finally evaporated to give the catalyst. In preferred manufacturing processes, a solution of a soluble molybdenum, tungsten and vanadium compound is refluxed, then a phosphorus compound is added. The preferred methods of preparation are those which lead to the best results in the following special embodiments.

Preferred quantitative ranges apply to the catalysts of the above formula. Thus, preference is given to catalysts which contain phosphorus in the range from about 0.5 to about 3, that is to say catalysts in which b is 0.5 to 3. Furthermore, preference is given to those catalysts which contain at least one of the elements copper, tin, antimony, arsenic, cerium, boron, chromium, iron, nickel, cobalt, uranium, manganese, silver or rubidium. Of particular importance are catalysts which contain antimony in an amount of 0.1 to 6 according to the above formula.

The catalyst used in the process according to the invention can be used as a pure active ingredient or physically bound to a carrier. Numerous suitable carriers are known. It has been found that silica, zirconium oxide, diatomaceous earth, titanium oxide and aluminum oxide generally maintain the activity of the catalyst, while silica gel and alumina gels tend to reduce the effectiveness of the catalyst. The catalysts mentioned can be used with or without a support.

The catalysts used in the process according to the invention can also be present as a coating on a solid inert support. Examples 8 to 14 show a corresponding coating process. For example, when a porous solid support is wetted with water so that no water remains on the surface, a powder of the catalyst material is brought into contact with the support while rotating it in a container such as a simple glass bottle. Coated catalysts have been found to be particularly effective in controlling the reaction temperature.

As already mentioned, the process according to the invention for the oxidation of an unsaturated aldehyde to the corresponding unsaturated acid is known per se. In this process, a feed of unsaturated aldehyde with molecular oxygen is passed over the catalyst. The feed may also contain a diluent, usually water vapor. The ratio of the reactants in the feed can vary within wide limits. There are usually 0.2 to 4 moles of molecular oxygen per mole of unsaturated aldehyde. The amount of diluent can vary widely, but is usually in the range of 1 to 10 moles of diluent per mole of unsaturated aldehyde.

As already mentioned, the reaction is carried out at a reaction temperature of 200 to 600 ° C, wherein

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Temperatures of 300 to 400 ° C are particularly interesting. The reaction can take place under negative pressure, positive pressure or normal pressure and the contact times are preferably between a fraction of a second and 10 seconds or more. The reaction can be carried out in a fluidized bed or, more usually, in a fixed bed reactor.

As already said, the process according to the invention relates to the production of acrylic acid or methacrylic acid from the corresponding unsaturated aldehyde. The process is particularly important in the production of methacrylic acid from methacrolein because of the very high yields that are achieved and the small amount of by-products.

Examples 1 to 7 Preparation of Methacrylic Acid from Methacrolein Various catalysts according to the invention are prepared as described below and tested in the oxidation of methacrolein to methacrylic acid.

Examples 1 and 2 W0.8Pi.3V2Mo12Ox - an aqueous slurry containing 86.2 g Mo03, 7.7 g 85% H3P04, 7.5 g V203 and 10.8 g ammonium para-tungstate was prepared and refluxed overnight cooked, evaporated and dried at 120 ° C overnight.

Examples 3 and 4:

W3P], sV3Moi2Ox - first an aqueous solution of 11.5 g 85% H3P04, 141.2 g (NH4) 6Mo7024 • 4H20 and 53.9 g (NH4) 6W7024 • 2H20 is prepared in 1500 ml water. 23.4 g of NH4V03 are added to this solution. The resulting slurry is deep red and turns orange when heated further. The resulting mixture is evaporated and dried at 120 ° C. overnight.

Example 5

Wi.2PV3Mo12Ox —A solution of 17.6 gNH4V03 is made in 1 liter of water. 105.7 g are added to this solution

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(NH4) 6Mo7024-4H20 added and the mixture is heated with stirring until the solid is dissolved. 5.76 g of 85% H3P04 are added to the resulting solution, whereupon the solution turns red. This mixture is mixed with 16.2 g of ammonium para-tungstate, whereupon all the solids appear to be dissolved. The mixture is evaporated to dryness and the resulting solid is dried at 110 ° C. overnight. It is ground so that it passes through a sieve with a mesh size of 0.84 mm, and the sieved solid is heated to 430 ° C. for 2 hours.

Example 6

Wi, 2P2V3Mo12Ox - The procedure of Example 5 is repeated, except that 11.52 g of 85% H3P04 are added instead of 5.76 g of 85% phosphoric acid.

Example 7

Wi, 2P3V3Mo12Ox - The procedure of Example 5 is repeated, but instead of 5.76 g of 85% phosphoric acid, 17.30 g of 85% H3P04 are added.

A reactor with a reaction zone of 20 cm3 is built from a stainless steel tube with an inside diameter of 1 cm. A mixture of methacrolein, air and water vapor in a ratio of 1: 6.3: 5.2 is passed over the catalyst at the temperature given in the table below. The compositions of the catalysts and the results obtained with these catalysts are also shown in Table 1. The results are calculated as follows:

30% yield with one pass

35

% Conversion =

% Selectivity =

Mol of product formed x 100 mol of methacrolein added

Moles of converted methacrolein x 100 moles of methacrolein added

Mol of methacrylic acid formed X 100 mol of converted methacrolein

Table 1

Oxidation of methacrolein to methacrylic acid with WPVMo containing catalysts

Example catalysts reaction contact results%

temperature time yield

° C sec. Methacrylic-acrylic acid selectivity acid conversion

1

Where. «P i.3V2Mo] 2Ox

385

4.6

12.7

14.6

70.6

18.0

2nd

W0.8P, jV2MO12OX

355

4.8

29.9

0.0

65.9

45.4

3rd

W3P, .5V3MOI2OX

365

4.8

53.2

2.5

82.9

64.2

4th

W3P ,, 5V3MoI2Ox

335

5.0

53.4

2.6

75.3

70.9

5

W, JPV3Mo12OX

355

4.8

17.1

2.1

48.4

35.3

6

W1i2P2V3MO12Ox

385

4.5

26.9

3.7

70.0

38.4

7

W ,, 2P3M3MO12OX

355

4.7

27.2

4.0

60.3

45.1

Examples 8 to 14 Supported active catalyst material. An active catalytic material of the formula W3P2V2Mo12Ox 60 was prepared by dissolving 706.26 g (NH4) 6Mo7024 -4H20, 280.91 g (NH4) 6W4024 • 8H20 and 78.00 g NH4V03 in 3 l boiling distilled water. Cooking was stopped after 3 hours and stirring continued for a weekend. The resulting solution was 65

76.86 g of 85% H3P04 were added and the mixture was boiled down, the solid was dried at 110 ° C. and calcined at 415 ° C. for 1 hour.

This active catalyst powder was applied to Alundum particles (trade name "Norton SA-5209"). The particles were placed in a glass bottle and wetted with water. The water content was reduced to 2.4 g per 25 g particles using a hot air stream. The active catalyst powder was crushed to a size of less than 0.297 mm. While the glass bottle was rotated at an angle, about 17 g of the active ingredient powder per 25 g of Alundum were added in five individual portions. During each addition, the glass flask was rotated for 15 to 45 minutes. A catalyst was thus obtained from one

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Alundumträger and a firmly adhering layer of the effective catalytic material. The catalyst was then dried in the drying cabinet at 110 ° C. over the weekend; it was composed of 39.8% W3P2V2Moi2Ox and 60% Alundum. In the same way was a catalyst with 34.8% W3P2V2Mo12Ox and 65.2% Alundum

(«Norton SA-203») and a catalyst with 20.4% W3P2V2Mo] 2Ox and 79.6% Alundum («SA-203»). Using the above reactor and feed, these catalysts were tested in the production of methacrylic acid from methacrolein, the results of which are shown in Table 2.

Table 2

Production of methacrylic acid with W3P2V2Mo12Ox alone and in coated form

example

catalyst

Reaction temperature

Contact time

Results% yield

° C

Sec

Methacrylic acid

conversion

selectivity

8th

Active ingredient alone

360

2.6

68.9

92.5

74.5

9

Active ingredient alone

360

2.5

67.5

93.5

72.2

10th

39.8% active ingredient 60.2% Alundum

380

4.4

65.2

93.3

69.9

11

39.8% active ingredient 60.2% Alundum

365

4.6

59.4

85.7

69.3

12

34.8% active ingredient 65.2% Alundum

360

4.7

66.2

92.3

71.7

13

20.4% active ingredient 65.2% Alundum

370

4.6

65.5

86.4

75.8

14

20.4% active ingredient 65.2% Alundum

390

4.5

64.1

92.2

69.5

Example 15

Catalysts according to the invention containing optional elements.

Various catalysts of the invention with various optional elements were made as shown below.

Example 15

Rbo, 7sW3P1.sV2,25Mo120x - First a solution of 141.2 g (NH4) 6Mo7024 • 4H20 and 11.52 g85% P3P04in2 1 water was prepared. 53.9 g (NH4) 6W7024 • 2H20 and then 17.6 g NH4V03 were added. 7.2 g of RbC2H302 were then added to this mixture, the mixture was boiled down and the solid was dried at 110 ° C. overnight.

Example 16

Sn0.5Cu2W1i2PV3Moi2Ox — A slurry was made by adding 72.0 gMo03, 11.36 g V2Os, 3.13 g Sn02 and 5.65 g 85% H3P04 to 800 ml water. This was refluxed with stirring overnight. Then 9.19 g of finely divided tungsten metal was added, then the mixture was refluxed for 2 hours, whereupon 16.63 g of cupriacetate were added and the mixture was refluxed for a further 1 2 hours. The slurry was evaporated to dryness and dried at 110 ° C overnight.

Examples 17 and 18

33.3% Sn0.5Cu2W1.2PV3Moi2Ox and 66.7% Alundum - The catalyst from Example 16 was applied to Alundum according to the procedure of Examples 8 to 14, a catalyst consisting of V3 active catalyst material and 2/3 Alundum being obtained.

30 Examples 19 and 20

Sn0.5Cu2W1.2P2V3Mo12Ox - The procedure of Example 16 was repeated, but with twice the amount of phosphoric acid.

35 Example 21

SbW3P2V2Mo12Ox - 88.2 g (NH4) 6Mo7024 ■ 4H20, 35.1 g (NH4) 6W4013 • 8H20 and 9.7 g NH4V03 were dissolved in 500 ml water. The solution was boiled for 5 hours and left overnight with stirring. 9.6 g of 85% H3P04 were then added to the cold solution. After stirring for about an hour, the mixture was heated again. 6.05 g of Sb203 were added to the hot solution, the mixture was boiled down and the solid was dried in the drying cabinet over the weekend.

Examples 22 to 32 The catalysts were prepared according to the procedure of Example 21, according to the formula Mt W3P2V2Moi2Ox so (with the exception of the catalyst with rhodium which contained Rh0.2S and the catalyst with iron which contained Fe2), the corresponding amounts the following compounds were used instead of the antimony oxide:

Bi203, Ni203; Cr (C2H302) -H20; Co (C2H302) -4H20; 55 RhCl3 • 3H20; Cd (C2H302) 2 • 2H20; Fe (N03) 3 • 9H20; AgC2H302; Sr (0H) 2-8H20; UO ^^ C ^^ O; Ce (C2H302) 3 l, 5H20.

These catalysts were used in the above manner for the production of methacrylic acid, the results shown in Table 3 resulting:

At spii

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Table 3

Manufacture of methacrylic acid with catalysts containing optional elements

Catalyst facultate. Temp. Contact yield

Element (s) ° C time / sec. Methacrylic selectivity acid conversion

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Rb0.7sW3P l, sV2) 2sMOj20x

Rb

370

4.6

47.2

89.0

53.0

Sn0.5Cu2W I> 2PV3Moi2Ox

SnCu

355

4.6

17.4

57.0

30.5

33.3% active, acc. Ex. 16

SnCu

390

4.4

27.1

63.2

42.9

66.7% alundum

33.3% active, acc. Ex. 16

SnCu

365

4.6

23.4

60.7

38.6

66.7% alundum

Sno, 5Cu2Wli2P 2 ^ '3 M Oj 2 O x

SnCu

390

4.4

21.6

67.4

32.3

Snol5Cu2W 2V3Moi2Ox

SnCu

360

4.6

20.5

63.3

32.4

SbtWaPzVjMotjO ,,

Sb

360

2.6

68.5

93.8

73.0

BiW3P2V2Mo12Ox

Bi

370

4.6

61.1

96.0

63.6

BiW3P2V2Mo12Ox

Ni

380

2.6

61.1

96.1

64.1

CrW3P2V2Mo12Ox

Cr

405

2.4

47.0

82.8

56.8

CoW3P2V2Mo12Ox

Co

435

2.3

46.2

83.2

55.5

Rho, 25W3P 2 V'2 O12 O x

Rh

385

2.6

19.9

64.5

30.9

CdW3P2V2Mo12Ox

CD

365

2.6

63.5

89.6

70.9

Fe2W3P2V2Mo12Ox

Fe

455

2.3

17.5

58.4

30.0

AgW3P2V2Mo12Ox

Ag

350

2.6

42.7

57.7

74.0

UW3P2V2Mo12Ox

U

380

2.5

57.5

91.1

63.1

SrW3P2V2Mo12Ox

Sr.

390

2.5

55.0

91.4

60.2

CeW3P2V2Mo12Ox

Ce

425

2.4

39.8

81.3

48.9