DE1071690B - Process for the production of nitriles and / or imiiiden of bienzo carboxylic acids - Google Patents

Description

GERMAN

kl. 12 ο 14

INTERNAT. KL. C 07 C

PATENT OFFICE

EDITORIAL NOTICE 1071690

D 26331 IVb / 12 ο

REGISTRATION DATE: AUGUST 29, 1957

Of 000J

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: DECEMBER 24, 1959

The present invention relates to the preparation of nitriles and / or imides of Benzene carboxylic acids by catalytic conversion of mixtures of alkylbenzenes with ammonia and molecular oxygen at elevated temperature in the vapor phase.

This way of working is known. Numerous compounds have already been used as catalysts, e.g. B. Vanadium Oxide, Tin oxide and mixtures thereof have been proposed (see US Pat. No. 2,499,055). These results however, were unsatisfactory because high yields were not achieved.

The inventive method is an improvement in which it is using a new catalyst succeeds in nitriles of the benzene series in higher yield and with increased efficiency to manufacture.

The process according to the invention is characterized in that mixtures of alkylbenzenes, Ammonia and molecular oxygen in the vapor phase at elevated temperature with a catalyst brings into contact, which consists of a mixture of vanadium oxide and tin oxide, which is activated on one Alumina is applied before application to a temperature between 1000 and 1500 ° C had been heated.

When producing the catalyst, vanadium oxide and tin oxide can be used together from one Solution of their salts are precipitated on the carrier material. The carrier material can also be mixed with a solution soaked in salts of these two metals, dried and placed in air or oxygen for transfer be heated into the corresponding oxides. The mixture of vanadium and tin oxides is on one activated alumina deposited previously, for example 12 to 24 hours, at a temperature had been heated between 1000 and 1500 ° C. The heat treatment is preferably carried out in air. According to a preferred embodiment of the method, the mixed ones are deposited Oxides by evaporating a solution of vanadyl oxalate and tin chloride on the heat-treated Clay. Then the catalyst is heated in air to around 350 to 400 ° C to produce the oxalate and To convert chloride into the corresponding oxides. The ratio of vanadium and tin oxides to activated clay can vary significantly; so can z. B. 0.1 to 20, preferably about 10 percent by weight, based on the total weight of the catalyst. Also the relative amounts of vanadium and tin can vary considerably, but they are preferably included an atomic ratio of vanadium to tin like 2: 1.

Method of manufacture

of nitriles and / or imides

of benzene carboxylic acids

Applicant:

The Distillers Company Limited,
Edinburgh, (UK)

Representative: Dr. W. Schalk, Dipl.-Ing. P. Wirth,

Dipl.-Ing. G. E. M. Dannenberg

and Dr. V. Schmied-Kowarzik, patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Claimed priority:
Great Britain 19 September 1956

David James Hadley and Edward James Gasson,

Great Burgh, Epsom, Surrey (UK),

have been named as inventors

In order to facilitate the distribution of heat in the strongly exothermic reaction, it is advisable to use the Granules of the active catalyst with the granules of an inert diluent material, e.g. B. brick, Pumice stone or technical grade silicon carbide. This makes it possible to reduce the heat emission easy to regulate per unit volume of the reaction mixture.

Compounds which are suitable for conversion to nitriles by the process of the invention are Alkylbenzenes containing at least one radical of the general formula

-CR ₂

in which R ₁ , R ₂ and R _{3 are} either a hydrogen atom or a lower alkyl group. Toluene and ethylbenzene are converted into benzonitrile, o-xylene into phthalimide, o-tolunitrile and phthalic acid dinitrile, m-xylene into isophthalic acid dinitrile and m-tolunitrile, p-xylene into terephthalic acid dinitrile and p-tolunitrile in tricyclic and mesitylene

909 690/568

benzene. Furthermore, o-, m- and p-diisopropylbenzene and o-, m- and p-cymene are suitable as starting materials.

The reaction can take place in a relatively wide temperature range, e.g. B. between 300 and 500 ° C can be carried out. It is preferable to work between 330 and 420 ° C. The contact time can also vary, but contact times between 0.25 and 20 seconds have proven to be well suited. In order to achieve higher yields, the temperature during the heat treatment of the catalyst, the contact time and the reaction temperature must be carefully selected. The higher the temperature during the heat treatment of the catalyst support, the less active the catalyst, ie the most active catalysts are obtained by treatment at about 1500 ° C. Such catalysts have a surface area of about 15 to 0.5 m ² / g. Heat treatments at more than 1500 ° C are not advisable for practical reasons. In the case of the more active catalysts, it is necessary to use less strict reaction conditions in the range given above with regard to contact time and reaction temperature, and vice versa.

In addition, with a medium activity catalyst, e.g. B. a catalyst whose carrier is at 1250 or 1300 ° C was treated, the contact time and the reaction temperature to achieve high yields are matched in a similar way, with the longer contact time being matched with the lower Reaction temperature is combined in the range given above, and vice versa. Preferably will the heat treatment of the catalyst and the reaction temperature selected so that a contact time from 0.5 to 5 seconds can be adhered to.

The process according to the invention can be operated like the known vapor phase catalysis process will. The catalyst can be in a fixed bed or in a moving bed. In view of the strong heat build-up and the need for precise temperature control a fluidized bed process can be of particular advantage.

The ratio of ammonia to alkylbenzene in the reaction mixture can be within a wide range vary. Preferably, however, at least IV2 to 2 times the stoichiometrically necessary Amount of ammonia used, d. H. about IV2 to 2 moles of ammonia per mole of alkylbenzene, if one Mononitrile or imide is formed, and about 3 to 10 moles of ammonia per mole of hydrocarbon, provided the end product is a dinitrile.

The concentration of the alkylbenzenes in the reaction mixture is preferably kept low, and it is expedient to concentrations of no more than about 2 percent by volume of the total gaseous To use reaction mixture; the preferred concentration is IV2 percent by volume. Will be a If higher concentrations are used, explosive mixtures of the alkylbenzene and oxygen can be formed.

The oxygen concentration in the reaction mixture can vary within a wide range. Preferably a gas mixture containing at least 5 percent by volume of oxygen is fed to the reaction mixture and contains at least 3 moles of oxygen per mole of alkylbenzene, e.g. B. air or an oxygen-air mixture.

The nitriles and / or imides prepared according to the invention can be prepared in a conventional manner, for. B. by Cooling the hot gases, deposited, with the nitriles either as liquids or as solids There are substances that can be dried in the usual way. They are valuable intermediates too Making other important connections. In particular, certain dinitriles can be used for the production used by plastics (polyester).

The following examples illustrate the process of the invention. Parts are parts by weight.

example 1

It was a catalyst made from tin and vanadium oxides, based on heat-treated alumina at atomic level Ratio of (V: Sn) 2: 1 were deposited, manufactured as follows:

5.5 parts of vanadium pentoxide were stirred with 11 parts of water, heated to 90 ° C. and then 14 parts of oxalic acid were added with stirring over the course of 1 hour. The resulting deep blue vanadyl oxalate solution was mixed with a hot aqueous tin chloride solution (6.85 parts of Sn Cl ₂ -2 H ₂ O in 9 parts of water) and the mixture was poured over 48 parts of alumina (a particle size that could be passed through sieves with a mesh size of 1, 6 to 0.8 mm pass), which had previously been subjected to a 22-hour heat treatment at 1400 ° C. The impregnated clay was dried in an oven with frequent stirring and finally dried at 400 ° C. in a stream of air and ammonia to convert the metal salts into oxides.

A mixture of 1.5 percent by volume p-xylene and 6 percent by volume ammonia in air was passed over this catalyst in a glass reaction vessel immersed in a metal bath at 360 ° C. and the exhaust gases were passed over this catalyst at a rate of 600 liters per hour per liter of catalyst space cooled in a glass jar. The yield of terephthalic acid dinitrile was 76.5%, based on the xylene fed. In addition, p-tolunitrile was obtained in 8.2% yield and carbon dioxide in 5% yield.

For comparison purposes, a tin and Vanadium oxide catalyst deposited on a non-heat-treated alumina carrier was made in the following way:

5.5 parts of vanadium pentoxide were converted into vanadyl oxalate in the manner described and this Solution 13.7 parts of tin (II) chloride dissolved in 100 parts of water were added, whereupon the solution passed through the gradual addition of aqueous ammonia was made slightly alkaline with stirring. the The gray-green precipitate was filtered off, washed free of chloride with water and then in the oven at 100 ° C dried. The cake obtained was broken up and passed through a sieve (with a mesh size from 1.6 to 0.8 mm) sieved. A mixture of 1.5 percent by volume was then poured over this catalyst p-xylene and 6 percent by volume ammonia in air with a contact time of 6 seconds. at At a reaction temperature of 288 ° C., the maximum yield of terephthalic acid dinitrile was 36%. At the somewhat higher reaction temperature of 310 ° C., the yield of terephthalic acid dinitrile was only 21 per cent and 40 per cent of the p-xylene fell as carbon dioxide at.

Example 2

A catalyst was prepared as in Example 1 with the modification that the proportions of tin oxide and vanadium oxide were each halved, d. H. the catalyst contained 5.72 percent by weight vanadium

pentoxide and 4.78 percent by weight zinc oxide. 1.5 percent by volume of p-xylene was deposited over this catalyst and 6 percent by volume of ammonia in air at a rate of 1200 liters per hour per liter of catalyst space directed. This corresponds to a contact time of 3 seconds (calculated for room temperature and pressure). Three experiments were carried out at different reaction temperatures Results listed in Table 1 are:

IO

Reak
tionstem
temperature
⁰ C Tabel 1 Yield to
p-tolunitrile
¹ Vo yield
on coals
dioxide
° / o attempt
No. 394
406
415 Yield to
Terephthal
acid dinitrile
% 2.5 7.5
14th
14th 1
2
3 80
79
74

Example 3

A mixture of 1.5 percent by volume of m-xylene and 6 percent by volume of ammonia in air was at a reaction temperature of 400 ° C above that in the example 2 described catalyst passed. The contact time was 3 seconds. There were the following Results obtained:

Isophthalic acid dinitrile 65.4%

m-Tolunitrile -

Carbon dioxide 18 ° / o

Example 4

The procedure of Example 3 was repeated, except that the concentration of ammonia 8 percent by volume and the reaction temperature was 403 ⁰ C. The following results were achieved:

Isophthalic acid dinitrile 72.6%>

m-Tolunitrile -

Carbon dioxide 9.4 per cent

Example 5

A made of tin oxide and vanadium oxide on alumina heat-treated at 1400 ° C for 22 hours Catalyst was prepared as in Example 1 with the modification that the amount of Vanadium pentoxide was halved so that the ratio V: Sn was 1: 1.

A mixture of 1.5 percent by volume of p-xylene and 6 percent by volume of ammonia was poured over this catalyst conducted in air with a contact time of 6 seconds. It were at different reaction temperatures carried out three tests, the results of which are shown in Table 2:

Table 2

attempt
No.
5 Reak
tionstem
temperature
⁰ C Yield to
Terephthal
acid dinitrile
⁰ zo Yield to
p-tolunitrile
"/ 0 yield
on coals
dioxide
»/ 0 1
2
3 360
370
380 51 *
67
59 17th
9
2 8th
12th
25th

Claims (9)

PATENT CLAIMS: 1. Process for the preparation of nitriles and / or imides of benzene carboxylic acids by Implementation of mixtures of alkylbenzenes, ammonia and molecular oxygen at increased Temperature in the vapor phase in the presence of catalysts containing tin and vanadium, characterized in that the catalyst used is a mixture of vanadium oxide and tin oxide on an activated alumina carrier, before the catalyst mixture is deposited, to a temperature between 1000 and 1500 ° C had been heated. 2. The method according to claim 1, characterized in that a catalyst is used which has a ratio of vanadium and zinc oxide to activated alumina between 0.1 and 20, preferably 10 percent by weight. 3. The method according to claim 1 and 2, characterized in that the atomic ratio of Vanadium to tin in the catalyst is 2: 1. 4. The method according to claim 1 to 3, characterized in that the catalyst with granules an inert diluent such as brick, pumice or technical grade silicon carbide. 5. The method according to claim 1 to 4, characterized in that the reaction is carried out at a Temperature between 300 and 500 ° C, preferably between 330 and 420 ° C, performs. 6. The method according to claim 1 to 5, characterized in that there is a duration of contact from 0.25 to 20 seconds. 7. The method according to claim 1 to 6, characterized in that there is at least 5% oxygen and at least 3 moles of oxygen per mole of hydrocarbon-containing mixture of Respondent used. 8. The method according to claim 1 to 7, characterized in that a reaction mixture, which contains IV2 to 2 times the theoretically necessary amount of ammonia is used. 9. The method according to claim 1 to 8, characterized in that a reaction mixture, which contains about IV2 volume percent of the alkyl substituted hydrocarbon is used. © 909 690/568 12.59