DE1220845B - Process for the production of unsaturated, aliphatic aldehydes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4WWWt PATENT OFFICE

EDITORIAL

Int. Cl .:

C 07c

German KL: 12 ο-7/03

Number:
File number:
Registration date:
Display day:

U10009IVb / 12o
July 30, 1963
July 14, 1966

It is known that the catalytic oxidation of olefins leads directly to the products of complete Oxidation (carbon oxides and water) lead or stopped at various preliminary stages of this oxidation (aldehydes or unsaturated acids). If you z. B. Acrolein by oxidation wants to produce propylene, the problem to be solved is to find catalysts that a high conversion of propylene as well as the highest possible yield of acrolein with a possible low formation of secondary products (acetaldehyde, acrylic acid, etc.) or of products enable complete degradation (carbon monoxide, carbon dioxide, water).

But it has now been found that when using vigorous oxidation catalysts such. B. of the oxides of vanadium, copper, tungsten, etc., and to a great extent those subject to oxidation Degrades olefins as well as the desired carbon oxidation products. You always get Products of complete oxidation with a small amount of aldehydes. There are therefore There are currently numerous processes in which one can use the energetic catalysts listed above were used together with other compounds that have the task of oxidizing to slow down. These moderators are oxygen compounds of bismuth, antimony, arsenic, Phosphorus, selenium, tellurium, etc.

Nevertheless, among the numerous known mixed catalysts, there are very few that are also good Conversions and high yields of unsaturated aldehydes, d. H. ensure good effectiveness. Certain catalysts do indeed ensure excellent conversion rates, close to 100%, however the yield is relatively low, which means a waste of the starting materials. Others, on the other hand, only give weak degrees of implementation, e.g. in the order of 10%, allow but in contrast, high yields close to 90%.

From French patent specification 1,293,960 it is known to use certain compounds of vanadium, tungsten and / or molybdenum with arsenic acid as catalysts for the oxidation of olefins to saturated aldehydes, ketones and carboxylic acids. According to the invention, on the other hand, unsaturated aldehydes are to be produced, and the breaking of the double bonds, which is aimed at in the process of the French patent, is to be avoided according to the invention. The object of the invention is to provide unsaturated ali processes for the production of unsaturated,
aliphatic aldehydes

Applicant:

UCB (Union Chimique-Chemische Bedrijven)

S. A., Brussels

Representative:

Dr.-Ing. A. van der Werth and Dr. F. Lederer,

Patent Attorneys, Munich 8, Lucile-Grahn-Str. 22nd

Named as inventor:

Cyrille van Eygen, Watermael-Boitsfort;

Pol Lambert, Uccle;

Antonin Hendrickx, Brussels (Belgium)

Claimed priority:

Great Britain July 30, 1962 (29 226)

to produce phatic aldehydes with improved yields and improved conversion rates.

The invention relates to a method for manufacturing ¹ lung of unsaturated aliphatic aldehydes by oxidation of olefins in the gas phase at elevated temperature in the presence of molecular gaseous oxygen and inert diluent gases, optionally also of water vapor, as well as a catalyst, optionally supported on an inert carrier.

The process is characterized in that the reaction is carried out with a catalyst Calcination of molybdenum arsenotungstate has been obtained, introducing a volatile oxygen-containing one Arsenic compound performs.

The results in terms of yield and degree of conversion that have been achieved according to the invention are much better than those obtained by the best known methods, e.g. B. with the method of French patent specification 1275 204, have so far been obtained.

The oxygen content of the catalysts used according to the invention is not critical and can vary according to the manufacturing method, the heat treatment, the catalysts before their use be subjected to fluctuate.

609 589/341

3 4

The catalysts used according to the invention in order to give them special physical properties

which give by the calcination of molybdenum arsenic.

ramat can be obtained via the stoichio- In general, the catalysts fall into the form

metric ratio addition from a low of calibrated grains or powders to that

Excess tungsten, arsenic or molybdenum can be pastilated or granulated in the 5. One can

be accompanied by an oxidized state. they are also produced in the form of squeezable pastes

If a catalyst is used that only contains tungsten, which can then be converted into grains of suitable size.

contains oxide, the degree of conversion of the propylene can change. The catalysts can also be obtained

Reach 90%, however, the yield of acrolein will be in the form of particles that are good for one

only with a few percent at most. If, on the other hand, fluidization processes are suitable and good consistency

set for this, the catalyst also contains arsenic, must have resistance to abrasion,

the yield of acrolein more than tenfold; The catalysts can be in the solid, fluidized

Conversion of the propylene, however, takes place in a moving or moving catalyst bed according to the usual

noticeable dimensions. Surprisingly, methods are used

by adding relatively small 15% of the specific surface area of the catalysts

Amounts of molybdenum to the arsenotungstate also have a certain importance. Actual-

Catalysts an additional improvement was found to be found with the catalysts borrowed

the implementation as well as the yield. Molybdenum with a specific surface area below 200 m ² / g

behaves like a promoter here. You can also use the Brunauer, Emmett and Teller method

nor do the conversion and the yield affect 20 the best results while catalysts

by changing the reaction temperature, the Re- with such of above 200 m ^{2 / g a Nei-}

duration of the campaign and through the use of carriers, higher quantities of products of the full

fabrics. When using supported catalysts, permanent oxidation (carbon oxides and water)

will deliver yields of over 90% at a moderate one.

Implementation achieved. Such a catalyst is suitable. The reaction mixture is composed of

particularly good for the production of acrolein the olefin to be oxidized, from oxygen or

with a cycle of the unreacted propylene. a gas containing oxygen, e.g. B. Air and

By choosing the carrier, the active substance can also be used as a diluent gas (nitrogen, propane, carbon

efficiency and productivity of the catalyst increases substance oxides) and possibly from water vapor,

will. Such a catalyst is particularly suitable 30 For 1 part by volume of olefin, one generally uses

for the production of acrolein, starting from my 0.5 to 2 parts oxygen, 0 to 5 parts

Propylene without recycling the latter. Steam and 2 to 8 parts of inert gas. The re-

The catalysts used according to the invention action temperature is between 300 and 700 ° C,

are preferably not claimed between 350 and 450 ° C. How to use the

manufactured as follows. 35 exemplary embodiments can be seen, one obtains

Considerable results are obtained at temperatures starting from suitable quantities

Arsenic acid and an alkaline wolframate, below 400 ° C.

Arsenotungstic acid in the usual way and extra- Atmospheric pressure is preferred as pressure,

The aqueous solution thus obtained is then mixed with ether. However, it is also possible to use pressures above

Solution of the heteropolyacid after acidification with a 40 atmospheric pressure work if you look for good

Mineral acid. The ethereal extract is introduced to dissipate the heat of reaction,

steams. The contact time depends on the working temperature

For the production of molybdenum arsenotungstate and the desired degree of conversion. In general, the aqueous solution of arsenotungsten is inversely proportional to the contact time, acidic to a molybdate solution, preferably to the temperature and proportional to the ammonium molybdate conversion method, and the degree of vaporization obtained is between 0.05 and 30 seconds , pre-aqueous solution. The residue is dried, preferably between 0.1 and 10 seconds,
calcined and sifted. The above-mentioned aqueous recovery of the unsaturated aldehydes from solution can also be used to impregnate one of the reaction products according to the usual carrier. 50 methods, e.g. B. by absorption in water or

It is also possible to remove the active solid substance with a suitable solvent or by removing

a carrier and dilute with water or cooling below the deposition point.

To form a paste in an organic liquid, arsenic tungstic acid is known to decompose in

to dry this mixture and at a suitable heat release of arsenic oxygen

Temperature, e.g. B. between 100 and 500 ° C, to kai- 55 bonds that have a vapor pressure at

- interest. Temperature above 300 ° C can no longer be neglected.

AIs carrier k ann is usually is at lässigbar. This results in a continuous

Production of catalyst carriers used reduction of the arsenic content in the catalyst

Take substances, e.g. B. molten aluminum oxide, gates and thus a loss of effectiveness. Ver

Carborundum, beryllium oxide, titanium oxide, borophos- 60 different analyzes of the catalysts during

phat, aluminum phosphate, pumice stone. A prior use has shown that the arsenic content is up to

However, the preferred carrier is a silica gel with values that are too low, corresponding to a

macroporous structure. atomic ratio of arsenic to tungsten of 0.15: 18

The catalysts can be lowered before they are used. This loss is compensated for by introductory

in a manner known per se an activation ⁶ 5 tion an oxygen-containing volatile Arsenverbin-

treatment or stabilization treatment in case of temptation, e.g. B. arsenic acid in the reaction chamber

Temperatures between 100 and 500 ° C in the presence at the same time with the reactants and encountered

of air, water vapor, inert gases, so that the initial activity is maintained or restored.

posed. This volatile arsenic compound can be introduced in a gaseous, liquid or solid state will. They can also be introduced continuously or from time to time, regardless of which physical form of the volatile arsenic compound is used.

To introduce the arsenic compound in a gaseous state, one can use the gaseous mixture, z. B. preheat a mixture of propylene, nitrogen and air and then over pastilles made of arsenic acid oxide conduct, which are heated to a temperature of 120 to 150 ° C.

The introduction of an arsenic compound in a solid state is particularly interesting in the case of use of a fluid bed. Arsenic can then be obtained in the form of oxides in a solid and powdered state to add. The constant movement of the fluidized bed quickly and effectively distributes the arsenic oxides in the whole catalyst mass.

The volatile arsenic compound can just as well be introduced in liquid form, e.g. B. in a solution in water or an aqueous hydrochloric acid solution. This method is equally applicable to a Reaction with a fixed catalyst bed as well as for a reaction in a fluidized bed.

The amount of volatile oxygen-containing arsenic compound which must be used in order to maintain or restore the activity of the catalysts is relatively small. Calculated as As ₂ O ₃ , it is 0.1 to 25 g, preferably 0.25 to 2.5 g As ₂ O ₃ per 1000 g of the unsaturated aldehyde formed.

The recovery of the arsenic compounds caused by the gaseous Products are entrained, is advantageously done by cooling the latter. Man can e.g. B. these arsenic compounds as an aqueous solution from the gas flowing out of the reaction chamber before the unsaturated aldehyde is separated off condense out. The aqueous solution of the arsenic compounds that is obtained in this way can enter the reaction space be reintroduced if necessary, thereby significantly reducing the total consumption of arsenic compounds in the reaction can be.

An electron microscopic examination of a catalyst that evaporates with the introduction of Arsenic acid oxide works in the reaction mixture, showing that the surface area of the catalyst is in excess is covered with arsenic acid oxide crystals, while a catalyst that does not undergo such treatment has been subjected to a superficial distribution of arsenic acid, which is much less dense, although its arsenic content (according to the Analysis) can sometimes be much higher than that of a catalyst treated with arsenic acid oxide became.

The catalysts are very specific. The yield of acrolein is generally 80 to 90%; in addition, efficiencies of 55 to 60% and are obtained in a single pass more.

Under the degree of conversion of propylene (isobutylene), the percentage of propylene (isobutylene), the during the reaction is converted, under effectiveness of acrolein (methacrolein) the percentage of the propylene (isobutylene) used, which is converted into acrolein (methacrolein), under

45 Acrolein (methacrolein) yield is the percentage of propylene (isobutylene) converted into acrolein (Methacrolein) is converted and under productivity the amount of acrolein (methacrolein) that is in a unit of time is generated by a unit of catalyst, understood.

example 1

1500 g of sodium paratungstate _{Na 2} WO _{4 -2H 2} O are dissolved in boiling water with stirring and 135 g of an aqueous 60% arsenic pentoxide solution are added. The mixture is kept at the boil for 15 minutes, then cooled and gradually 2000 g of chemically pure hydrochloric acid (d = 1.19) are added while cooling to 0 ° C. The arsenic tungstic acid is then extracted with diethyl ether and the ether is evaporated on a water bath. An aqueous solution of the heteropolyacid thus obtained is then prepared and its arsenic and tungsten content is adjusted.

744 g of this solution (with a titer of 44.5% tungsten and 2.8% arsenic) are added to a solution obtained by dissolving 17.65% ammonium paramolybdate in 100 ml of hot water. It is evaporated to dryness in an air bath at 100 ° C. and then heated to 450 ° C. for 24 hours. The mass is broken up and calibrated into granules 1.5 to 3 mm in diameter. The specific surface area of this catalyst, measured by the BET method, is 15 m ² / g. The catalysts produced in this way have an average composition corresponding to an atomic ratio As: W: Mo of 3.5: 18: 1.3 and contain a small excess of arsenic acid oxide compared to the ratio of the heteropolyacid H ₆ As ₂ O ₈ (WO ₃ ) ₁₈ -rcH ₂ O. 375 ml of this catalyst are placed in a tubular U-shaped reaction vessel made of non-oxidizable steel and having an internal diameter of 15 mm. The reaction vessel is immersed in a thermostatically controlled metal bath. A gaseous mixture of 9% propylene, 77% air and 14% water vapor is sent through the catalyst. At the same time arsenic acid oxide is introduced in an amount of 0.25 g per hour and the following results are obtained:

Contact time
Implementation, %
Yield,%

420 ⁰ C

55.3
58.7

temperature
420 ° CI 420 ° CI 430 °

66.5
87.5

76.3
80.0

62.9
83.5

450 ° C

74.9 80.1

The effectiveness of acrolein increases by more than 60% (test at 420 ° C., contact time 3 seconds).
For comparison, if one works without As ₂ O ₃ introduction with a contact time of 1 second, the following result is obtained:

Implementation, %
Yield, "%.

temperature
380 ⁰ CI 400 ⁰ CI 42O ⁰ C

47
81.6

51
80.6

60
81.5

In addition, the catalyst gradually deactivates as a result of the evaporation of arsenic oxide.

Example 2

This example shows that the carrier can play an important role.

Catalyst on fused aluminum oxide
(Catalyst A)

200 g of the catalyst of Example 1 are pulverized and this powder is mixed with 60 ml of water. The paste obtained is treated in a ball mill for 48 hours. 400 g (200 ml) of molten aluminum oxide are then impregnated with the catalyst paste and the mixture is dried on a water bath. It then sets the drying for 24 hours at 100 ° C in an air bath continued _S i and then for 24 hours at 450 ° C.

Beryllium Oxide Catalyst (Catalyst B)

100 g of the catalyst of Example 1 are finely ground and the powder thus obtained is mixed while drying with 100 ml beryllium oxide, broken to 1.5 to 3 mm in diameter. The mass is then moistened with a minimal amount of water to ensure that the paste adheres to the substrate. Then it is dried for 16 hours at 100 ° C.

Catalyst on macroporous silica gel
(Catalyst C)

The macroporous silica gel which is used has a density of 0.4 and a specific surface area (BET method) of 485 m ² / g and a pore volume of 0.81 cm ³ / g.

100 g of the finely ground catalyst of Example 1 are mixed in the drying process with 100 ml of the silica gel broken into grains 1.5 to 3 mm in diameter. The mass is then moistened with a minimal amount of water to ensure that the paste adheres to the carrier material and dried for 16 hours at 100 ° C. The catalyst obtained in this way has a specific surface area of about 100 m ² / g.

The results obtained with these three catalysts using the gaseous mixture of the reactants of Example 1 are the following:

Tempe
rature Contact
Time Around
settlement yield Catalyst A
Catalyst B
Catalyst C 420 ° C
44O ⁰ C
460 ° C 2
1
0.25 45.0%
29.0%
65.0% 88%
93.6%
73.5%

The beryllium oxide catalyst enables a very high yield; on the other hand, one wishes one very much high productivity, the catalyst can be used on macroporous silica gel since the necessary contact time there is remarkably short. If, on the other hand, great effectiveness is sought (without circulation), the unsupported catalyst according to Example 1 can in particular be used.

Example 3

In this example, several ways of supplying an arsenic compound in liquid form to a catalyst during the reaction to maintain its activity are shown. 10 ml of the catalyst of Example 1 are placed in a tubular Pyrex reaction vessel with an internal diameter of 7.5 mm. A gaseous mixture of 10% propylene, 75% air and 15% water vapor is passed into this reaction vessel. In a row of heated elements at the top of the reaction vessel, 0.25 ml of a 1N solution of hydrochloric acid containing 1.5 percent by weight of As ₂ O _{3 is} injected once every hour.

At 400 ° C with a contact time of 1.5 seconds, the following results are obtained:

Implementation 70%

Yield 86%

Effectiveness 60%

If you inject once every 4 hours with an amount of 0.25 ml of the above Performing a mixture containing arsenic under the same conditions, the following results are obtained:

Implementation 62%

Yield 84%

Effectiveness 52%

If one takes 0.25 ml of a mixture containing 1.5 percent by weight of As ₂ O ₃ in a 0.1 N hydrochloric acid solution under the same conditions once every 4 hours, the following results are obtained:

Implementation 57%

Yield 89%

Effectiveness 51%

The consumption of elemental arsenic to maintain the catalyst activity is:

In the first case:

2.00 g per 1000 g of acrolein produced, in the second case:

0.55 g per 1000 g of acrolein produced, in the third case:

0.55 g per 1000 g of acrolein produced.

Example 4

This example differs from example 3 in particular by the fact that the Working temperatures are higher.

The reaction equipment, the catalyst, the supplied gaseous mixture are the same as they were also used in Example 3. After 16 hours of working at 420 ° C with a contact time of 1.5 seconds without the addition of a volatile arsenic compound (comparison), the following results Results:

Implementation 80%

Yield 72.50%

Effectiveness 57.5%

After 50 hours the activity of the catalyst will decrease and the results will be:

Implementation 43%

Yield 85%

Effectiveness 37%

From this moment on you inject into the Re-. Action vessel every 4 hours 0.25 ml of a solution of 1 η-hydrochloric acid with a content of 1.0 percent by weight

Implementation 43%

Yield 85%

Effectiveness 37%

10

cent of As ₂ O ₃ , and the results are then as follows:

Implementation 64%

Yield 89%

Effectiveness 57%

If you work with the same contact time instead of 420 at 440 ° C, the following results are obtained Results:

Implementation 70%

Yield 82%

Effectiveness 57%

It can be seen that the activity of the catalyst is practically restored to the initial value by adding a suitable amount of As ₂ O ₃ . The consumption of arsenic, which is necessary for the catalyst to function properly, is in the order of 0.5 g per 1000 g of acrolein produced.

ao

Example 5

In this example, the effect of a volatile arsenic compound in aqueous solution or in aqueous hydrochloric acid solution shown.

The reaction apparatus, the catalyst, the supplied gaseous mixture are the same as in Examples 3 and 4. The working temperature is 420 ° C as in Example 4. During the first For comparison, no arsenic is injected into the reaction vessel for 50 hours. At the end of this period the activity of the catalyst has decreased, and the results of the work at this moment are as follows:

35

If, for the purpose of introducing the arsenic into the reaction space, the As ₂ O ₃ hydrochloric acid solution of Example 4 is replaced by an aqueous solution with the same As ₂ O ₃ concentration, but the injection is carried out every 4 hours, the following results are obtained:

The amount of arsenic that must be added to obtain the best activity of the catalyst, increases to 2 g per 1000 g of acrolein produced.

If the amount of arsenic injected is reduced to a quarter, i. H. on 0.5 g per 1000 g produced Acrolein, the following results are obtained:

Implementation 65%

Yield 82.5%

Effectiveness 53.5%

Claims (3)

Patent claims: 1. Process for the preparation of unsaturated aliphatic aldehydes by oxidation of Olefins in the gas phase at elevated temperature in the presence of molecular, gaseous Oxygen and inert diluent gases, possibly also of water vapor, as well a catalyst optionally held on an inert support, characterized in that that the reaction with a catalyst obtained by calcining molybdenum arsenotungstate has been obtained, with the introduction of a volatile oxygen-containing Arsenic compound performs. 2. The method according to claim 1, characterized in that the volatile oxygen-containing Arsenic compound introduces arsenic acid oxide. 3. The method according to claim 1 or 2, characterized in that the volatile oxygen-containing arsenic compound, calculated as Al ₂ O ₃ , in an amount of 0.1 to 25 g, preferably 0.25 to 2.5 g per 1000 g of the introduces generated unsaturated aldehyde. Implementation 66% Yield 86% Effectiveness 57% 45 Publications considered: German Auslegeschrift No. 1103 911; British Patent No. 821,999; French patents No. 1,272,358,
447, 1275 204, 1290 737, 1293 960; Fuel Chemistry, 42 (1961), pp. 375 and 376; Chemical and Engineering News, 9/10, 1961, pp. 56 and 57. 609 589/341 7.66 © Bundesdruckerei Berlin