DE2058004A1 - Process for producing a nitrile - Google Patents

Description

Imperial Chemical Industries Limited London (Great Britain)

Process for the production of a sitrile

The invention relates to the catalytic ^ oxidation cyclic and acyclic, saturated hydrocarbons and especially the production of nitriles by cafcalytic Oxidation of alkanes and ammonia. Such an oxidation is referred to below as "ammoxidation",

For the production of acrylonitrile and methacrylonitrile by catalytic ammoxidation of propylene and isobutylene Numerous methods have been used using a feed gas having a relatively low hydrocarbon concentration suggested. In these methods, for example that described in British patent specification 876,446 Process, any alkane present was considered inert and any propane or butanes contained in the feed gas assumed that they only act as a diluent and play no role in the catalytic conversion. In contrast to what is stated in this and others

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Patent specification (s) can be nitriles according to the invention and in particular to produce acrylonitrile and methacrylonitrile by catalytic ammoxidation of the corresponding alkane »

The invention is based on maintaining high partial pressures of the alkane vapor in the feed gas of the catalytic conversion, compared with the partial pressure usually used in the ammoxidation of alkenes to nitriles; As a result of these measures, the desired nitrile falls in sufficient quantities in the exhaust gases to enable its extraction even at relatively low degrees of conversion (difference in the quantities of hydrocarbons in the feed and exhaust gas divided by the quantity of hydrocarbon in the feed gas) on an industrial scale.

The invention thus relates to a process for the production of a citrile by catalytic ammoxidation of a ferrous alkane, which is characterized in that a feed gas containing the alkane and ammonia in the vapor phase, in which the alkane has a partial pressure above 0.35 atmospheres (absolute) has, at a temperature below 500 ⁰ C passes over a suitable, solid catalyst.

The catalyst is selected from the viewpoint that the reaction takes place at temperatures below this numerical value; it has been shown that particular economic advantages can be obtained if the reaction is carried out at such moderate temperatures.

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The partial pressure of the alkane should preferably exceed 0.70 atmospheres (absolute).

The respective catalyst usually consists of the oxides of the respective elements. In the event that one If oxygen-free feed gas is used, the catalyst can be used either by frequently interrupting the feed gas supply and then supplying an oxygen-containing one Regenerate regeneration gas or by passing the catalyst through a separate regeneration zone. However, preference is given to working with a feed gas containing alkane, ammonia and oxygen, with such a regeneration becomes unnecessary.

The method according to the invention can be practical Perform at atmospheric pressure or above atmospheric pressure. In every case this is in the feed gas contained alkane in such a volume percentage amount that their product with the pressure of the feed gas exceeds 35 and preferably 70 in atmospheres (absolute).

When operating at or about atmospheric pressure, the alkane makes at least 35 and preferably 70 or more % By volume of the feed gas. Especially with the higher ones Alkane concentrations and when working when printing over Atmospheric pressure is preferably used as the oxygen used for the reaction. The amount of alkane should be in the feed gas must be small enough to accommodate an intake

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allow the inert constituents of the air.

If the amount of alkane in the feed gas is within the specified limits, the ratio of the gaseous Reactants, for example depending on the form of the reactor used and depending on the one chosen Catalyst mass, vary widely. However, the preferred volume ratio of ammonia to alkane is 1/40 to 1/8, while the preferred volume ratio of oxygen to alkane is 1/50 to 1/3.

The catalyst is chosen according to various criteria. One of these considerations is that it is advantageous to perform the reaction at a reaction temperature of at least 340 ⁰ C. Another aspect that plays a role in the selection of the respective catalyst is the degree of conversion.

The active constituents of the catalyst composition preferably consist essentially of the oxides of two or three special metals or from a stoichiometric or non-stoichiometric compound of such metals with oxygen.

The oxide catalyst mixtures can be mixed together produce suitable oxides in finely divided form. In a very simple way, however, they can be

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by mixing oxides, hydroxides, or hydrated Oxides in aqueous suspension and evaporation of the mixture obtained to dryness or filtration of the suspended Produce solids, pearly aqueous suspensions can be prepared by various conventional methods. For example, in the case of Antimony and tin, the metal oxidized with concentrated nitric acid; in the case of vanadium, molybdenum and uranium, on the other hand, a solution of a salt, e.g. ammonium metavanadate, ammonium paramolybdate or uranium nitrate, be hydrolyzed.

After the suspension has been evaporated to dryness, the mixed oxide product is preferably also heat-treated (hereinafter referred to as "calcining") in order to facilitate the production of a reproducible catalyst. The calcination can be performed from 600 ° to 850 ⁰ C in air at a temperature of 300 ° to 95O ⁰ C, preferably. Since the final oxidation state of the mixed oxide catalyst mass (which can have a stoichiometric or non-stoichiometric composition) as well as its crystal and phase structure are determined to a large extent by the final calcining, it should be understood that oxides and other suitable compounds are used as starting materials of the metals in question can be used in which the metals are present in different oxidation states than they are contained in the final Katalyeatormssse.

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For example, trivalent or pentavalent antimony compounds or tetravalent or pentavalent vanadium compounds be used. In order to promote the reproducibility of the catalyst, the final calcining should be carried out preferably carried out for at least 4 hours.

The ratio of the metallic components in the catalyst mass can vary over a considerable range ψ ; the optimum ratio depends on the particular elements and the operating conditions under which the catalyst is used. This ratio can be determined experimentally, but without difficulty. Thus, for example, in the case of catalysts • with binary mixtures of vanadium and antimony this. Ätomverhältnis of vanadium and antimony in a conventional manner 0 _s 05 to 1.5, preferably 0.1 to 0.7.

fc The catalyst is preferably used in particle form in order to facilitate gas / solid contact in the reactor. By "particles" is meant powder, granules, pellets and the like. The particles can consist of the catalyst material alone or be mixed with particles of an inert and refractory material, which can optionally be present as the main component of the solid catalyst. On the other hand , the catalyst material

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rial as a layer on the surface of an inert support be applied.

The process according to the invention is preferably carried out continuously with average feed gas / catalyst - Contact times of 0.01 to 10, in particular 0.1 to 3 seconds, carried out. "Contact time" is the numerical value in seconds obtained by dividing the. Debris volume of the catalyst due to the gas volume flow per second (measured under room conditions).

The reactor used can be a fluidized bed or fixed bed reactor or a reactor with a act static bed; the catalytic ammoxidationB reaction can be run isothermally or adiabatically. Preferably, the desired nitrile from the Exhaust gases along with by-products, such as carbon dioxide, are withdrawn, while the remaining gases, the mainly from unreacted alkane, ammonia and Oxygen, mixed with appropriate amounts of fresh, gaseous reactants and delivered to the reactor inlet be returned.

The alkane, which may be a cyclic or acyclic alkane, preferably does not contain more than 20 carbon atoms, especially 3 to 8 carbon

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material atoms. Preferably the alkane consists of propane or isobutane, the nitrile being acrylonitrile or methacrylic ' nitrile occurs.

The following examples are intended to illustrate the process of the invention in more detail.

example 1

^ In the context of this example, the catalyst used consisted of antimony oxide activated with vanadium pentoxide, the relative weights being 82.1 and 18.8, respectively. The catalyst was prepared by adding 1.23 kg of metallic antimony to 5-9 liters of concentrated nitric acid; The addition rate was in this case controlled so that the temperature of the solution remained at 80 ⁰ C. When the addition of antimony was complete, the antimony pentoxide suspension obtained was heated to boiling in order to decompose the excess nitric acid. Then the Antiraon pentoxide was

"slurry cooled to room temperature.

In a second flask, 0.46 kg of ammonium metavanadate was added to 1.14 liters of 1% hydrochloric acid. The orange slurry thus obtained was with the. Antimony pentoxide slurry mixed and the solution evaporated to dryness. During the evaporation, the

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Slurry stirred continuously.

The wet, solid residue was dried for 16 hours calcined at a temperature of 15O ⁰ C and 8 hours at a temperature of 650 ⁰ C. The calcined solid was comminuted to a particle size corresponding to 10-25 BSS sieves, whereupon 20 ml of the comminuted catalyst were introduced into the reactor. The bulk density was 1.1 g / ml.

. It became a feed gas (Gas 1) with a high propane content and, for comparison purposes, a feed gas (gas 2) with a low propane content, but otherwise of the same composition, was produced. The two gases had the following composition in vol .-%:

Gas Λ ' Gas 2 C ₃ H ₈ : 80% 5.0%

₃ χ 5% 5.0%

O ₂ ϊ '10% 10.0%

N ₂ · i. - ■ 5% · 80.0%

Each of the two gases was passed over the catalyst in a reactor at atmospheric pressure, at different temperatures and at different flow rates. For every flying speed and for every temperature, the proportion of acrylonitrile in the exhaust gas was approximated. Here the results ee given in Table I below were obtained. In this case, the temperature in each case which when using gas 1 at every flow

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speed led to an optimal yield of acrylonitrile.

Table I.

Plating speed temperature% acrylonitrile in the exhaust gas in 1 / hour in ⁰ C gas 1 gas 2

48.0 450 1.41 -... 0.10 96.0 480. 1.44 0.12 144.0 490 0.8? 0.08

Unreacted propane was separated from the exhaust gas and returned to the reactor.

Example 2

In the context of this example, the catalyst composition used again consisted of antimony oxide activated with vanadium pentoxide with the same relative weight amounts as in Example 1. The bulk density in this case was 2.1 g / ml. The catalyst was prepared in the manner described in Example 1, with the exception that the calcined catalyst was comminuted to a powder, whereupon the powder was mixed with graphite, pelletized and ^{calcined at a temperature of 650 0} O before it was finally closed a particle size corresponding to 10-25 BSS-Si * t> «n was reduced.

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The same feed gases (gas “1 and gas 2) were passed over the catalyst at atmospheric pressure} the corresponding ones Numerical values, in% by volume, for the acrylonitrile contained in the exhaust gas are compiled in Table II below :

Table II

Flow rate temperature gas 1 gas in 1 / hour in ⁰ C

48.0 430 2.1 0.12 96.0 470 2.3 0.15 144.0 500 1.8 0.11

Comparing these results with the results of Example 1, it is found that the amount of acrylonitrile in the exhaust gas had increased due to the change in the bulk density of the catalyst. The results further show the% decrease uale of acrylonitrile in the exhaust gas when the temperature is increased to 500 ⁰ C.

Example 3

The catalyst used in this example contained the following active ingredients (in amounts by weight)

Antimony tetroxide: 68.3 vanadium pentoxide: 3.9 stannous oxide: 29.0

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The catalyst was by slowly adding 75 »3 g of metallic antimony to 360 ml of concentrated SaI-. peter acid produced wherein the rate of addition was chosen so that the maximum temperature did not exceed 80 ⁰ C. After the addition of the metallic antimony was complete, the solution was kept at the boiling point until no more nitrous gases escaped. Then 33 g of tin were added and the solution was again heated to boiling temperature} it was then cooled to room temperature.

In a second flask 9> 6 g NH ^ VO * were added to 30 ml 1% HCl, whereupon the orange slurry obtained in this way was added to the slurry obtained in the first stage. The slurry was heated to boiling temperature and then cooled to room temperature and the pH was adjusted to 1.0. The precipitate which separated out was filtered off, washed, ^{dried at a temperature of 150 °} C. for 16 hours and ^{calcined at a temperature of 650 °} C. for 8 hours. Finally, the calcined material was crushed to a particle size equivalent to 10-25 BSS sieves. 20 ml of the crushed catalyst was placed in the reactor. The catalyst prepared in the manner described had a bulk density of 1.07 g / ml.

A feed gas (gas 1) and a reference gas (gas 2) of the same were passed over the catalyst located in a reactor

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Composition, like the gases of Example 1, (separately) directed. The results compiled in Table III below were obtained.

in 1 / h in ⁰ C gas 1 gas 2

Table III A he; , 29 temperature Gas 1 , 27 in ⁰ C 1 , 75 420 1 500 0 480

0 , 08 0 , 07 0 , 05

48.0

96.0

144.0

As in the previous examples, unreacted propane contained in the exhaust gas was recycled.

Example 4

In the context of this example, the catalyst used consisted of 90% by weight tin oxide and 10% by weight molybdenum oxide. The catalyst was prepared by adding 1 mol of (NH ^) ^ Mo «0 ^ to excess concentrated nitric acid (to precipitate MoO,). In a second vessel, 9 moles of anhydrous SnCl ^ were added to a large excess of water, whereupon the pH of the resulting solution was adjusted to 5.0. After the two slurries had cooled to room temperature, they were mixed, heated to the boil , cooled, filtered off and washed

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resulting residue was dried for 16 hours at a temperature of 15O ° O and 8 hours calcined at a temperature of 650 ⁰ C. The catalyst was finally comminuted to a particle size corresponding to 10-25 BSS sieves, whereupon 20 ml of the comminuted catalyst were poured into the reactor. The catalyst used had a bulk density of 1.9 g / ml.

In the manner described in Example 1, the feed gases also specified in Example 1 were over the catalyst directed. The following results were obtained:

Table IV

Flow rate temperature% acrylonitrile in the exhaust gas in 1 / h in ^Q C gas 1 gas 2

48 430 1.5 5 0.10 96 460 1.6 0.12 144 500 1.4 0.12 example

In the context of this example, a catalyst was used which contained 10% by weight of chromium oxide and 90% by weight of vanadium oxide as active ingredients. First, 9 moles of ammonium metavanadate were added to an excess of 1% HCl. Furthermore, 1 mol of Or (NO ₃ ) »was dissolved in water

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and the resulting solution was added to the VpOc slurry. Then the pH of the resulting mixture was adjusted to 8.0 by adding NH 4 OH. The precipitate formed was filtered, washed, calcined dried for 16 hours at a temperature of 15O ⁰ O and 8 hours at a temperature of 750 ⁰ O. The catalyst obtained in this way was crushed to a grain size corresponding to 10-25 BSS sieves, whereupon 20 ml (24.2 g) of the crushed catalyst were introduced into the reactor.

A feed gas of the same composition as Gas 1 of Example 1 at about atmospheric pressure was then fed over the catalyst located in the reactor at the space velocities and temperatures given below directed.

Table V

Space velocity Average volume percent acrylonitrile Vol / Vol catalytic reactor temperature in the exhaust gas

gate / std in ⁰ C 0.9 • 2400 430 0.6 4800 450 0.6 7200 480. Example 6

By dissolving 3 moles of ammonium metavanadate in excess

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Excessive 1% HCl and the addition of SnCl ^ to the solution obtained, a vanadium / tin catalyst containing 30% by weight of vanadium oxide and 70% by weight of tin oxide as active ingredients was prepared. The pH of the solution obtained was adjusted to 9 »O by adding NH ^ OH. The solution was evaporated to dryness, whereupon the residue obtained was ^{dried for 16 hours at a temperature of 0} C and then for 8 hours at a

Temperature of 65O ⁰ C was calcined. The catalyst obtained in this way was comminuted to a particle size corresponding to 10-25 BSS sieves. 20 ml (24.6 g) of this was placed in the reactor.

Using the same feed gas as in Example 5, the following results were obtained:

Table VI

Space velocity Average vol-% acrylonitrile in the vol / vol catalyst / reactor temperature exhaust gas P std door in ⁰ C

2400 450 1.0 · 4800 480 ^ 0.7 7200 500 0.6 Example 7

For the production of an antimony / iron catalyst were

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wherein the rate of addition was adjusted so that the solution temperature remained below 8O ⁰ C was added first 7 moles of metallic antimony in excess of concentrated nitric acid. 3 moles of Fe (NOx) ^ '6H ₂ O were dissolved in the SbgOc slurry obtained, whereupon the mixture obtained was heated to the boil to decompose the excess nitric acid. The solution was then cooled to room temperature and ammonia was added for neutralization; the pH of the solution was adjusted to below 8.0. The resulting precipitate was filtered, washed, calcined for 16 hours at a temperature of 150 ⁰ C and dried for 8 hours at a temperature of 65O ⁰ C. The catalyst obtained in this way was finally comminuted to a particle size corresponding to 10-25 BSS sieves. 20 ml of this was filled into the reactor. The catalyst had, as active ingredients, 70% by weight of antimony oxide and 30% by weight of iron oxide; it also had a bulk density of 1.60 g / ml.

With the same feed gas as in Example 5, the following were made Get results;

Table VII

Space velocity Average vol-% acrylonitrile vol / vol catalytic reactor temperature in the exhaust gas door / hour door in ⁰ C

2400 480 1.1 4800 500 0.9 7200 520 0.7

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Example 8

For the preparation of an antimony / tin catalyst first 1 mole of metallic antimony was added in excess of concentrated nitric acid, wherein the rate of addition was adjusted so that the solution temperature did not rise above 80 ⁰ C. The solution was heated to boiling temperature until no more nitrous gases escaped; then the solution was cooled to room temperature. 1 mol of tin was then added to the solution, heated to boiling temperature and finally cooled to room temperature. The cold slurry was adjusted to pH 8.0 by adding excess NH ^ OH. The resulting precipitate was filtered, washed, calcined for 16 hours at a temperature of 15O ⁰ C and dried for 8 hours at a temperature of 65O ⁰ C. The catalyst obtained in this way was comminuted to a particle size corresponding to 10-25 BSS sieves; 20 ml of this was filled into the reactor.

The catalyst had equal parts of antimony oxide and tin oxide as active ingredients and a bulk density of 1.60 g / ml.

With the same feed gas as in Example 5, the following results were obtained:

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Table VIII

Space Velocity Average Vol Acrylonitrile Vol / Vol Catalytic. Reactor temperature in the exhaust gas door / hour door in ⁰ O

2400 450 1.2. . 4800 470 1.3 7200 500 0.9 Example 9

For the preparation of an antimony / uranium catalyst first 1 mole of metallic antimony was added in excess of concentrated nitric acid, "wherein the rate of addition was controlled so that the maximum temperature of the slurry did not rise above 80 ⁰ C. The solution was for the decomposition of excess nitric acid to boiling 1 mol of UOp (NOz) 2 * 9 ^ 2 ° S ^el est was added to the resulting slurry. The pH of the solution was adjusted to below 8.0 by adding excess NH ^ OH. The precipitate which separated out was filtered off, washed, ^{dried for 16 hours at a temperature of 150 °} C. and calcined for 8 hours at a temperature of 650 ^° C. The catalyst obtained was then comminuted to a particle size corresponding to 10-25 BSS sieves ; 20 ml of this was filled into the reactor.

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Using the same feed gas as in Example 5> at a space velocity of 7200 vol / vol catalyst / hr and an average reactor temperature of 470 ⁰ C., the yield of acrylonitrile in the exhaust gas volumenprozentuale 0.94.

Examples 4, 6, 7 and 8 illustrate the decrease in the acrylonitrile yield when the reactor temperature is increased to over 500 ^° C.

Example 10

This example illustrates the production of methacrylonitrile using a feed gas from Isobutane, oxygen and ammonia.

For the preparation of an antimony / vanadium catalyst 75 »2g metallic antimony was added to 360 ml of concentrated nitric acid initially carefully, the rate of addition was controlled so that the maximum temperature did not exceed 80 ⁰ C. When the addition of antimony was complete, the solution was heated to the boil in order to decompose the excess nitric acid. The resulting slurry was then cooled to room temperature.

64.4 g of ammonium vanadate in 200 ml of a 1% HCl solution were introduced into a wide vessel. The

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Orange slurry held was added to the SbgOc slurry prepared in the first step, and the resulting slurry was heated to boiling, then cooled, filtered and washed. The resulting residue was dried for 16 hours at a temperature of 15O ⁰ C and then calcined for 8 hours at a temperature of 650 ⁰ C. The catalyst prepared in the manner described was comminuted to a particle size corresponding to 10-30 BSS sieves; 10 ml of the comminuted catalyst were diluted with 90 ml of SiO2 of the same particle size, after which the mixture obtained was poured into the reactor.

A feed gas with the following composition in % by volume):

Isobutane: 85 Oxygen: 10 Ammonia: 5

was passed over the catalyst at a space velocity of 7200 vol / vol catalyst / hour and an average reactor temperature of 465 ^{0 O.} The volume percentage yield of methacrylonitrile in the exhaust gas was 1.05.

Example 11
In the context of this example, which shows the implementation of the

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Settlement in superatmospheric pressures illustrated,
the catalyst was in that described in Example 2
Prepared manner, but with the exception that the calcined catalyst material was converted into 5.175 mm pellets. Feed gases of propane, ammonia and oxygen were passed over the catalyst obtained at a space velocity of 5000 vol / vol catalyst / hour and under the conditions given below with the following results:

Table IX

Pressure in propane propane average vol-% acrylonitrile

'Atmosphere in the food partial borrowed catalyst in the exhaust gas

ren (ab- segas in pressure in satortempera-

solut) Vo 1-% atmosphere at ⁰ C

85 ren (from 435 1.5 43 absolutely) 409 0.8 1.2 . 1.0 Example 12 2.0 0.9

Example 11 was repeated, except that other partial pressures of propane were used. Here were the following Get results:

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propane Tabel X Vol-% acrylonitrile Pressure in in the store propane average in the exhaust Atmosphere segas in Partial liche cataly ren (from Vol ~% print in satortempera absolutely) Atmosphere temperature in ⁰ C ren (from 85 absolutely) 1.2 1.8 1.5. 449 0.8 5.6 1.6 415

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Claims (12)

Claims / 1 y
/1.yVerfahren for the production of a nitrile by catalytic ammoxidation of an alkane, characterized in that a feed gas containing the alkane and ammonia in the vapor phase ■ in which the alkane has a partial pressure of over 0.35 atmospheres (absolute), passes over a suitable solid catalyst at a temperature below 50O ^{0 C.} 2.) The method according to claim 1, characterized in that the partial pressure of the alkane in the Speiseges 0.70 atmospheres (absolute) exceeds. 3.) Process according to claims 1 or 2, characterized in that that the alkane more than 35 vol .-% d, it feed gas matters * M-,) Process according to one of the preceding claims, characterized in that the alkane is at least 70 vol .-% constitutes the feed gas. 5 ·) Method according to one of the preceding claims, characterized in that the feed gas is the alkane contains oxygen-containing gas and ammonia. 6.) The method according to claim 5 »characterized in that the feed gas has a pressure that is practically - 25 109823/2273 does not differ from atmospheric pressure; that the alkane makes up at least 70% by volume of the feed gas and that the oxygen-containing gas consists of practically pure Oxygen or oxygen-enriched air. 7.) The method according to claim 5 »characterized * that the volume ratio of ammonia to alkane between 1/40 and 1/8 and the volume ratio of oxygen to alkane is between 1/50 and 1/3. 8.) The method according to claim 5> characterized in that the feed gas has a pressure exceeding atmospheric pressure and that the concentration of the alkane in the feed gas is such that the product of its volume concentration in percent and the absolute pressure of the feed gas exceeds 35 in atmospheres. 9.) The method according to claim 8, characterized in that the oxygen-containing gas consists of air. 10.) Process according to one of the preceding claims, characterized in that the reaction temperature is at least 340 ⁰ C. 11.) The method according to any one of the preceding claims, da- ■ characterized in that the alkane has at most 20 carbon atoms. 109823/2273 12.) The method according to claim 11, characterized in that
that the alkane has between 3 and 8 carbon atoms. 13 ·) Method according to one of the preceding claims, characterized in that, starting from propane or isobutane, the nitrile is acrylonitrile or methacrylonitrile manufactures. 109823/2273