DE2421702A1 - PROCESS FOR MANUFACTURING PHTHALIC ANHYDRIDE - Google Patents

Description

The invention relates to a method for producing Phthalic anhydride, which is a mixture of o-xylene and molecular oxygen contacted with an oxidation catalyst at a temperature of about 200 to about 600 ° C.

The oxidation of o-xylene to phthalic anhydride is known. The known reactant ratios, reaction conditions and other parameters are practically the same same as in the method according to the invention.

A special group of catalysts has now been found which are particularly effective in this reaction. These catalysts are very easy to manufacture and allow smooth temperature control and a higher conversion per pass.

In the German patent specification 1 442 590 the manufacturer

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Creation of a catalyst containing the oxides of vanadium by making a paste of titanium dioxide and vanadium oxide and coating porcelain balls with this paste described.

It has now been found that certain catalysts are particularly suitable for the oxidation of o-xylene to phthalic anhydride.

The invention relates to a process for the preparation of phthalic anhydride, in which a mixture of o-xylene and molecular oxygen exposed to an oxidation catalyst at a temperature of about 200 to about 600 C, which is characterized in that an oxidation catalyst is used which consists of (a) essentially one inert carrier having a particle size of at least about 20 microns having an outer surface and (b) one Coating of a catalytically active material on the outer surface of this carrier, which is attached to the outer surface of the inert carrier adheres firmly, the catalytically active material containing a vanadium oxide in such an amount that the The weight of the vanadium is less than 10% of the total weight of the oxidation catalyst.

The catalysts used according to the invention make this possible Performing a controllable reaction with higher conversions to phthalic anhydride per pass and advantageous low levels of worthless by-products. The catalysts are also particularly easy to manufacture and are friction-resistant (resistant to wear and tear). As stated above, this is essential

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Borrowed feature of the present invention in the use of a to see new catalyst in the known oxidation of o-xylene. This catalyst gives particularly good results this reaction.

The catalyst used according to the invention is around one that consists of an inert carrier and a firmly adhering coating made of a catalytically active material. The substantially inert support can be selected from any material that is at least partially porous and has such a physical strength that it is compatible with the catalyst precipitation process and the conditions of the Resists oxidation reaction. The porosity is for making of the catalyst is required and the stability of the support is necessary to achieve the desired friction resistance necessary.

Examples of suitable materials among the inert carriers are silicon dioxide, aluminum oxide, aluminum oxide-silicon dioxide, Silicon carbide, titanium dioxide and zirconium dioxide. This list is by no means complete, but only representative for those materials used in the present invention can. These carrier materials can of course also be replaced by many other materials, including those specified above Have properties.

As indicated above, the inert carrier has a particle size of at least 20 microns. There is none theoretical upper limit on the particle size of the inert carrier, but for practical reasons it should

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usually no larger than about 5 cm. Preferred carriers are those with a particle size of from about 0.2 to about 2 cm. The shape of the inert carrier can vary widely. Irregularly or regularly shaped supports can be used and, according to a preferred embodiment of the invention, spherical supports are used.

After the inert carrier component of the invention The catalyst used has been described, the active catalytic material is described in detail below.

As "indicated above, the active ingredients contain at least a vanadium oxide. According to the invention, vanadium pentoxide is preferred, which has been partially reduced with a reducing agent so that at least a portion of the vanadium in has a lower valence state than +5. The partial reduction of the vanadium in the catalyst is expedient in carried out the way that the vanadium pentoxide with a suitable reducing agent. Representative examples of suitable reducing agents are organic reducing agents, such as hydrazine, or finely divided metals such as tungsten or molybdenum.

Specific catalyst compositions of particular interest to the present invention are those of general formula

A D. V ₁₀ 0 from 12 χ

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where mean:

A Fe, Cr, Ni, Co, Ti, Mn, Cu, Zn, Ag, Bi, Mo, W or one

Mixture of

DB, Sb or a mixture of these,
a is a number from 0 to 5,
b is a number from 0 to 10 and
χ the number of oxygen atoms required to saturate the valences of the other elements present.

Among these catalysts, those containing boron or antimony or a mixture thereof are preferred. At the most preferred are those in which b is greater than 0 and less than about 5.

A very important aspect of the present invention is that the weight of vanadium in the catalyst is less than about 10% by weight of the total catalyst. Those catalysts which contain less than 5% vanadium are preferred, the best results being achieved with those catalysts which contain less than 1% vanadium.

Even if the vanadium oxide can be applied to the inert carrier in the form of the pure oxide, it is preferred to mix the catalytically active components with a solid diluent before coating the inert support. These solid diluents can conveniently be any of the carrier materials used or act any other solid diluent. Preferred solid diluents are titanium dioxide and silicon dioxide

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or a mixture of these. The solid diluent can Combined in any combination with the active ingredients, plural results in the desired catalyst. Most preferred are those catalysts which are a solid diluent and less than about 0.5 wt. Contains vanadium. ·

All of the coated catalyst used in the present invention is conveniently prepared by partially wetting the inert support with a liquid such as water. This partially wetted backing should contain some liquid, but no liquid should be visible on the surface be. The partially wetted (moistened) carrier is brought into contact with a powder of the active component mixture and the inert carrier is rolled in the active components. The contact between the powder and the inert carrier is easily achieved by placing the carrier in a closed container, the container with an inclined The level rotates and portions of the powder are added. Preferably, practically an entire portion of the powder is used The carrier is applied in the form of a layer before another portion is added.

The catalysts produced by this process exist of the inert carrier and a coating of the catalytically active substances adhering firmly to the outer surface of the carrier active components. The catalytically active components are retained on the surface of the carrier and it occurs practically no penetration of the active components into the inert carrier. The catalysts used according to the invention are thus in sharp contrast to the catalysis

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gates in which an inert support with an active catalyst has been impregnated by contacting the carrier with a liquid or slurry of the active components.

The coated catalyst according to the invention is used in the Oxidation of o-xylene to phthalic anhydride is used. This oxidation is a well-known reaction and the. Reaction conditions, the charging ratios and the structure of the reaction system do not differ significantly. those of the known processes. In general, the "Ho! Ratio of oxygen to o-xylene nux" needs about 4 moles per mole To be xylene, with no theoretical upper limit. I-7orraaIly, the molecular oxygen in Form of air added and the air / xylene ratio is usually within the range of about 40 to about or more.

The reaction temperature can vary widely, but it is usually within the range of about 200 to about 600 C, with temperatures of about 300 to about 500 G are preferred. The reaction can be carried out at atmospheric pressure, at elevated pressure or at reduced pressure. The egg ~ - inventive catalysts are best suited for the Fir.bed operation, when using small carrier particles but it is also possible to carry out the reaction in a fluidized bed reactor.

The catalysts according to the invention deliver particularly high levels Yields of phthalic anhydride and valuable by-products.

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The oxidation reaction can also be easily controlled when using the catalysts according to the invention. So far, the Exothermic reaction occurring in the reactor to the fact that the reaction got out of control with the invention However, it is possible to use catalysts without using special diluents or without using lower ones Reactant feed rates easily maintain a uniform temperature.

The invention is illustrated by the following examples, in which specific embodiments of the invention are described, explained in more detail, but not limited to: to be.

Examples 1 to 11

Distribution of phthalic anhydride using the invention coated catalysts.

There have been various catalysts according to the invention such as indicated below. A catalytic reactor

3
with a reaction zone of 20 cm was made from a stainless steel tube with an inner diameter of 1.02 cm. The reactor was placed in a metal block oven and a thermocouple was attached to the interior of the catalyst bed. O-xylene and air were passed through the catalytic reactor to achieve the desired contact time. The conditions and results of these experiments are given in the table below. Under the percentage of conversion per pass, the stated g-atoms of carbon in the product that were found in the effluent from the reactor are multi-

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multiplied by a factor of 100 and divided by the g atoms of the carbon introduced in the form of o-xylene _? to understand.

The catalysts used for the reactions were prepared as follows:

example 1

20.6% (Sb 3 VO + VT ₁ - ₉ ) and 79.4% Alundum

181.9 g of vanadium pentoxide were slurried in about 1 liter of water. To this stirred slurry was added 40.4 grams of tungsten metal powder admitted. The slurry was for several hours refluxed, during which time their color changed to deep blue-black.

A portion of this dark colored slurry, the 0.507 g atan Containing vanadium was transferred to another beaker. 7.84 g of boric acid were added to this. This mixture was refluxed for several hours. Finally 12.3 g of antimony oxide were added and the boiling reflux was continued for several hours. The final mixture was then evaporated to a thick paste and then dried overnight at a temperature of 110 ° C.

The black powder thereby obtained became in the form of a sheet on an alundum carrier (particle size 2.0 to -0.6 mm accordingly 10 to 30 mesh) applied according to the following procedure: 25 g of Alundum were wetted with 2 g of water by shaking

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in a round glass flask. The material was free flowing and dry on the outside. To this material in a rotating Vessel was added 12.5 g of the dried black powder in several portions. The powder was in shape one layer evenly applied to the surface of the alundum. The final product was dried and there were 6 g of active powder separated so that the end product consisted of 6.5 g of active powder and 25 g of Alundum, from which one Composition of 20.6% active material and 79.4% aluminum support was calculated.

Examples 2 and 3

9.7% (Sb ₉ B VO + W ° _n f.) And 90.3% Alundum

Practically in the same manner as in Example 1, a Similar catalyst made using the following amounts of material: 90.95 g vanadium pentoxide, 9.2 g Tungsten metal powder, 15.46 g boric acid and 24.3 g antimony trioxide. The finished slurry became thick Evaporated paste and dried as above.

This powder was sieved to a particle size of less than 0.3 mm (50 mesh) and applied in an analogous manner in the form of a layer: to an alundum with a particle size of 2.0 to 0.63 min (10 to 30 mesh) . After drying, 9.8 g of loose powder was removed so that the composition of the finished material was 9.7 % active coating and 90.3 % alundum backing.

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Examples 4 and 5

5 % (6B-V ₁₀ O • 94TiO) and 95 % Alundum

90.95 g of vanadium pentoxide were dissolved in 600 ml of distilled water Slurried and added 9.7 g of 85% hydrazine hydrate admitted. The slurry immediately began to darken. The slurry was refluxed for several hours cooked. Then 15.46 g of boric acid was added and refluxing was continued for several hours. There was a color change from deep blue-black to dark green. This mixture is referred to as Mixture A below.

A portion of Mixture A was removed so that the portion was the equivalent of 6.26 vanadium pentoxide contained. This portion was diluted to 350 ml with distilled water and 97 g of titanium dioxide were added. These Slurry was refluxed for 1 hour and then allowed to evaporate to a thick paste which was then over Was dried overnight at 110 ° C.

The dried product obtained above was sieved through a sieve having a mesh size of 0.3 mm (50 mesh) and then applied to the support in the form of a layer as follows: 30 g aluminum chips with a low porosity (Particle size 2.0 to 0, G4 mm (10 to 20 mesh)) were previously placed in a rotating round glass flask with 0.9 g of water moisturizes. The material was free flowing and it looked dry on the outside. To this "3 portions were added, each consisting of

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because from 0.53 g of the catalytically active powder. The powder was applied evenly to the alundum in the form of a layer. The coated material was left on overnight Dried at 110 ° C. The final composition was 5% active Component and 95% aluminum support.

Examples 6 and 7

5%. (6Sb ₀ B ₀ V ₁₀ O · 94TiO ₀ ) and 95% Alundum 2 3 1δ χ δ

To the remainder of mixture A with a calculated amount of vanadium of 0.93 g-atom, 22.6 g of antimony trioxide were added and the mixture was refluxed for 2 hours. This mixture was then referred to as Mixture B.

A portion of Mixture B was taken away with a calculated amount of vanadium, calculated as vanadium pentoxide, of 5.57 g. This portion was diluted to about 350 ml with distilled water and 87.2 g of titanium dioxide were added. the resulting slurry was stirred and then made into a thick one Paste evaporated, which was then dried at 110 C overnight became. The dried material was crushed and passed through a sieve with a mesh size of 0.3 mtn (50 mesh) sifted.

This dried material was processed in a manner analogous to that described above on aluminum chips with a low porosity and a particle size of 2.0 to 0.84mn (10 to 20 mesh) upset. 30 g of Alundum were added and this was then added. previously moistened with 1.1 g of water. 'The total amount of the

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brought dried active material was 1.59 g and it was added in three equal portions. The finished material consisted of 5% of the active coating and 95% of it the alundum carrier.

Example p

8% (SbBV. _? O _r ) and 92% Alundum

A portion of Mixture B was stirred and evaporated to a thick paste and dried overnight at 110g. The dried material was ground and sieved through a 0.3 mm (50 mesh) sieve. This material was applied to alundum particles having a low porosity and a size of 2.0 to 0.84 mm (10 to 20 mesh) in a manner analogous to the above. 30 g of alundum were used and these were previously moistened with 1.2 g of water. During the coating, 5 portions of the active powder, each consisting of 0.53 g, were added. The coated material obtained was dried at 110 ° C. overnight. The coating was uniform and contained only a small amount of loose powder so that the final composition was about 8 % active coating and 92% aluminum carrier.

Example 9

5% (6Sb ₂ B ₃ V ₃₂ 0 ^ 94Zr0 / CaO) and 95 % Alundum

A portion of the mixture containing 5.57 g of vanadium pentoxide B was diluted to about 300 ml with distilled water.

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To this a powdered calcium oxide was added, which with Zirlconia was stabilized, and the resulting slurry was stirred well and evaporated to a thick paste. This was dried overnight at 110 C and then ground and through a sieve with a mesh size sieved 0.3 min (50 mesh).

This material was applied in the form of a layer on 30 g of Alundurr with a low porosity, which had been previously moistened with 1.0 g of water. Three 0.53 portions of the catalytically active powder were applied to the Alundura. The material was dried at 110 ° C. and consisted of 5 % from the active powder and 95% from the Alundura *.

Example 10

5 % (6Sb BV 0. 94SiO ₀ ) and 95% Alundum

A portion of the mixture containing 5.57 grams of vanadium pentoxide B was diluted to about 300 ml with water. To this, 87.2 g of an amorphous diatomaceous silica powder was added. The slurry was agitated and thick Evaporated paste. This was dried overnight at 110 C and then ground and passed through a sieve with a clear Screen size of 0.3 mm (50 mesh).

This material was in the form of a layer in the same manner as in Example 6 on Alundum with a low Porosity and a particle size of 2.0 to 0.84 mm (10 to 20 mesh) applied. The finished product passed

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5% from the powder in the coating and 95% from the aluminum backing.

Example 11

5% (6VO 94TiO) and 95 % Alundum

6 g of vanadium pentoxide were slurried in 200 ml of distilled water. To this, 0.64 g of 85% strength ilydrazine hydrate were added. The brown suspension turned first dark green and then black. The slurry was stirred and refluxed for 2 hours. The slurry was then diluted to about 400 ml with distilled water and 94 grams of powdered titanium dioxide (anatase) was added. This slurry was stirred and refluxed for about 1 hour, then added . a thick paste left to evaporate. This material was dried at 110 ° C. for 3 hours and a portion was ground and sieved through a 60 mesh sieve to carry out the coating process.

30 f, _Alundum with a low porosity (particle size 2.0 to 0.84 mm (10 to 20 mesh) were distilled for 10 minutes Dipped in water and then dried on a paper towel. The linear volume of the water absorbed was 1.2 g. The alundum looked damp and sticky, so it was carefully taken with dried in a stream of air until its water content was reduced to 0.6 g. It was then free-flowing and outside dry.

The Alunduia with the

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Coated powder specified above, dr.s was added in three separate portions of 0.53 g each. The final product V was dried at 110.degree. The coating was uniform and only had a somewhat powdery surface. It consisted of 5% of the active material in the coating and 95 % of the alundum backing.

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Tabel

Oxidation of o-X ^ lol ^ to ^ phthalic acid anhydride

ο co ω

Example catalyst no.

20.6 % (Sb ₂ B 3 ^V 12 ° x ⁺ w ° _{1) 32} ) and 79 , 4 % Alundum 9.7% ( Sb ₂ B ₃ V ₁ 2 ° x ^{+ W} ° 0.6>' and 90, 3% Alundum

% V

Temperature,

bath

exothermic
reaction

377

385

Air / through XyIo1 transit time
in sec.

69

69

1.1

1.1

Conversion per pass in%

Phthalic maleic anhydride anhydride

35.4

45.8

S, 7

3.8

3 4 '

It

5 % (6B ₁₁ V _{1 0} 0 -94TiO) 0.14 and 95% alundum

Il

385 472 69 1.0 43.8 9.7 399 426 69 1.0 66.3 5.2

419

100

1.0

73.8

5.3

Continuation of the table

6 5% (6Sb ₀ B ^ V ₁ 0 .94TiO ₀ ) 0.12 399 417 100 1.0 75.0 6.6

<£ ö Jm4m Λ <£

and 95% alundum

ff ti

385 393 100 1.0 '77.7 4.4

8 8% < ^sb 2 ^B 3 ^V i2 ^O jP ^{and 3} » ^{12 3} " ^{459 10} ° ³ ^ ^{0 47} > ^{2 10} > ⁵ '

92% Alundum ι »

9 5 % (Sb ₉ BV 0 «94ZrO / 0.12 455 472 100 1.0 58.8 * ο CaO) and 95% Alundum

^ 10 5% (6Sb ₃ B ₃ V ₁₂ O _x '94SiO ₂ ) "427 443 100 1.0 66.8 4.9 ^ and 95% Alundum

g 11 5% (6V ₂ 0 ₅ * 94Ti0 ₂ ) 0.17 399 416 100 1.0 64.1 7.1 ^ω and 95% Alundum

* measured as total acid ^

Other reactant ratios can also be used in the same way as described in the preceding examples will; for example, air and o-xylene can be used in a ratio of -50: 1 under a pressure of 2 atmospheres and passed over a catalyst at a temperature of 325.degree to achieve the desired yields of phthalic anhydride.

In the same way as shown for the above-mentioned catalysts, other catalysts according to the invention, for example those made from 5% (1OCu Fe, V ₁₀ O '90TiO ₉ ) and

Z UjI JZ X £ *

95% titanium dioxide balls, 30% (2CoMo V ₁ 0 · 98ΤίΟ) and 70% silicon dioxide balls and 10 % (15Ni MnW, .Sb-V 0 · 85SiO _? ) And 90% aluminum orcyd balls used as catalysts according to the invention are used to achieve the particularly advantageous results of the invention.

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Claims (12)

Claims 1.; A process for the preparation of phthalic anhydride, in which a mixture of o-xylene and molecular oxygen is brought into contact with an oxidation catalyst at a temperature of about 200 to about 600 C, characterized in that an oxidation catalyst is used which consists of (a) a substantially inert carrier having a particle size of at least about 20 microns having an outer surface; and (b) a coating of a catalytically active material on the outer surface of the carrier adhered to the outer surface of the inert carrier adheres, the catalytically active material containing a vanadium oxide in such an amount that the weight of the vanadium is less than 10 % of the total weight of the oxidation catalyst. 2. The method according to claim 1, characterized in that a catalyst is used which is less than about 5 wt .-% Contains vanadium. 3. The method according to claim 1 and / or 2, characterized in that that a catalyst is used that is less than about Contains 1% by weight vanadium. 4. The method according to at least one of claims 1 to 3, characterized in that a catalyst is used in which the Vanadium is in the form of vanadium pentoxide, which is associated with a Reducing agent has been partially reduced so that at least some of the vanadium is in a lower valence state than +5. 409 851/1093 5. The method according to at least one of claims 1 to 4, characterized in that a catalyst is used, which contains a catalytically active material of the general formula AD, V ₁₀ O from 12 χ where mean: A Fe, Cr, Ni, Go, Ti, tin, Cu, Ag, Bi, Zn, Mo, W or one Mixture of DB, Sb or a mixture of these,
a is a number from 0 to 5,
b is a number from 0 to 10 and
χ the number of oxygen atoms required to saturate the valences of the other elements present. 6. The method according to claim -5, characterized in that in the general formula a is the number 0 and b is a positive number. 7. The method according to claim 5, characterized in that in the general formula b is a number greater than 0 and less than means about 5. 8. The method according to at least one of claims 1 to 7, characterized characterized in that a catalyst is used in which the inert support has a particle size of about 0.2 to about 2 cm. 409851/1093 9. The method according to at least one of claims 1 to 8, characterized in that the reaction is carried out at a temperature between about 300 and about 500 C v, ^T ird. 10. The method according to at least one of claims 1 to 9, characterized characterized in that a catalyst is consumed / ended, in which the catalytically active material consists of a mixture of the catalytically active components and a solid There is a diluent. 11. The method according to claim 10, characterized in that the solid diluent from the group consisting of titanium dioxide, Silica and mixtures thereof. 12. The method according to claim 10, characterized in that the oxidation catalyst contains less than about 0.5 weight percent vanadium. 409851/1093