DE1618497A1 - Process for the production of aromatic polynitriles - Google Patents

Description

Case 862

Halcon International, Inc., New York, N. Ϊ _Μ V ". St. Λ-

Procedure for division

The invention relates to the preparation of nitriles from polyalkyl substituted aromatic hydrocarbons. In particular, the invention relates to the improved ammoxidation of an aromatic dialkyl hydrocarbon s -, - z, Bo p ^ xylene, to the dinitrile.

Aromatic dinitriles, for example terephthalnonitrile and isophthalonitrile, are chemicals of very considerable importance, mainly because these substances are easily converted into aromatic; Dicarboxylic acids, for example terephthalic acid, can be converted. Such acids are known to be used in very large quantities for the production of synthetic fibers
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The conversion of polyvinyl aromatics into aromatic ones Nitriles by simultaneous reaction with ammonia and oxygen, the so-called amreuxydation realization is one today pretty well-known reaction, so far the implementation has been in

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the vapor phase by passing through the action participants carried out by a fixed catalyst bed under conditions which ensure a practical complete conversion of the hydrocarbon per pass. This procedure is true advantageous compared to previous methods, but results in a selectivity to nitrile of only about 75 ° *. As a result of local overheating and general reaction instatoiliiät ee was previously not possible when performing in technical To achieve consistently higher selectivities on a dimensional scale. In view of such shortcomings in the Ammoxydati If the reaction is still present, there is therefore a need for improved methods.

The invention aims to provide an improved method for Ammoxidation of polyalkyl aromatics to polynitriles.

The main aim of the invention is a method for ammoxidation from xylenes to the corresponding dinitriles and, in particular, an improved process for oxidation from p-xylene to terephthalonitrile.

Surprisingly, it has now been found that the selectivity the ammoxidation by applying a fluidized bed from a plague contact by controlling the reaction in the "¥ eii? e that only a partial conversion per pass is required, and by separation and recycling of as intermediates of the aramoxy

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dation-formed mononitriles, "improved considerably can be. In the practical implementation of the invention According to the procedure, an aromatic rolyalkyl hydrocarbon becomes in contact with a fluidized bed of solid kata ^ lysator ammoxidized under such Aimnoxidatlonbedingungen that about 20 to 80 * ί and preferably 30 to 60 '' of the poly

alkylaronates are implemented per round * .. Die Hoaktionemiöchüng is then separated into its various components. Aromatic polynitrile is the product of the process, while the unreacted polyalkylaromatic and as Aromatic mononitrile formed as an intermediate product into the Ammoxidation reaction can be returned. The reaction is weird carried out continuously, inventions can be easily calibrated Overall reaction selectivities of the polyalkylaroinates to give aromatic compounds Polynitrile of 90 or more preserved.

The invention is particularly applicable to the aramoxidation of use aromatic dialkyl hydrocarbons to dinitriles, but also includes the conversion of trialkylaroniates in dinitrile or trinitrile. Preferably the aromatic Compounds one aromatic ring and two or three alkyl substituents, each of which is no more than contains about 3 carbon atoms. Hit special benefit runs the method according to the invention is based on the arynoxydation of Xylenes and in particular the ammoxidation of p-xylene

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eur manufacture of terephthalonitrile apply.

For examples of individual embodiments of the inventive Process include the partial oxidation of m-rXylene to isopthalonitrile, the ammoxidation of mesitylene the corresponding trinitrile and the ammoxydation of ρ-diethy! benzene to terephtalonitrile.

When carried out in practice, the oxidation reaction carried out in a continuous fluidized bed process. The hydrocarbon is used along with appropriate amounts Ammonia or an ammonia-producing compound and one oxygen-containing gas continuously in the replacement of the Introduced into the reaction required amount per pass of reacted proportions. Circular hydrocarbons are also fed into the reactor as well as mononitrile formed in an earlier pass through the reaction zone. These gases are passed through a suitable ammoxidation catalyst in such a pot that the catalyst is kept in a whirling motion, similar to a boiling liquid "

Most appropriately, the overall composition of the in gases entering the reaction zone, based on the volume 1.0 to 3.0 pounds of polyalkylaromatic, 6 to 18 * ammonia or ammonia supplying compound, given in ammonia equivalents,

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7.0 to 9.0 * molecular oxygen ₉ t> 0 We 2.0 $ aromatic hononitr II and inert sase, 3 * B / water vapor and nitrogen, as the remainder. . Does the reaction "mixture normally nitrogen"-.Be; i®t ia was not necessary, but-i © general H ^ © Yorgugt »so much ^ äsö; 02? Daiapf : _ ■ zuuseteem that the Wßsseraarapfraeng® Ma sia 15 ^ and preferably about ₉ O 5 to 2.5 i> S © aamtli © sclii © effect "makes up for the reaction With a WasserdampfgehalV uäter 0.5 ^ falling sales somewhat, while a water vapor content over 2.5 ^ low -only a or no other part of the gate

Suitable ^ ifflraoxydatioasteBiperaturen liegeii in aitg®nieisi @ n in Beretch from 300 to 800 ° Ö ussd: f © ^ sugiwsise ■■ -. from 425 fct # 50 ©% ^ ■. Practically $ tma0ph ^ iseh @ - Bm & ki ^

However, higher pressures may be used if necessary. The gaseous mixture is introduced into the bed reaction in a continuous manner at a rate which is sufficient to keep the solid catalyst in a whirling movement. For example® b @ trä ^ t _: di @ speed; since "gas flow in general -: - t," JH5. -Mol / eii? ; * - "hour; until ... t _f 6. g ^ ol / oE» ² x hour wid precautionary. I "4-.bie I ₈ S g-Möl / cm ² χ: 'Stun.de * at Kataljeätor will size of 0.35 fei® 0 ^ 125 aai (60 Mt 12O'j83ah).

For d @ a methods according to the invention are. ^Which: 'are the same; Cataly-. eato3? <sn. "v © 3? s? endi> ßr _9. how. she fös ?; 4i © -known Ammoxydätionever-

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are used «Particularly preferred catalysts Bind vanadium and antifreeze support catalysts · You can but also other catalysts that are a compound of vanadium or vanadium oxide, preferably in combination with one Contains tin, chromium, lemuth platinum or molybdenum oxide, use. The catalysts are usually on supports made of aluminum oxide, silicon carbide, pumice stone, zirconium dioxide and the same. The catalyst has the most appropriate a particle size between 1 * 19 and 0 * 044 mm (16 and 325 mesh) and preferably between about 0.42 and 0.105 mm (40 and 140 mesh} »

The ammoxidation action is carefully controlled so that only a partial conversion of that introduced into the reaction zone Polyalkyl aromatics takes place. The person skilled in the art can do the desired Easily turn over per pass by setting the dwell time, the temperature and proportion of the reactants reach. In the practical implementation of the invention

gemäßeft method, a Polyalkylaromatenumsatz per pass of about 20 to 80 #, or, preferably, from 30 to SSO maintained ■ "The Heaktionemischung Wurd isolated by conventional methods. A particular advantage of the process according to the invention is that the aromatic polynitrile product is produced in extraordinarily high purity as a result of the high overall selectivity of the reaction. This fact has

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1818497

special importance because use Nttrilprodukt haaptsaohlieh for the manufacture of dicarboxylic acids used for Paserersseugung will. An essential requirement for dicarboxylic acids with paser quality is from serotlent borne - purity * The unreacted hydrocarbon, as well as ala intermediate product formed Mononitr.il, are continuously in the Amraoxidation recycled, wherein the circulating material with sufficient Kengen, on fresh ammonia, oxygen, dialkyl alcohol and water vapor or other inert gas mixed is to ensure practically constant packing for to maintain the reactor ...

The following examples illustrate the invention without representing it restrict.

example 1

According to the process of the invention, p-xylene is ammoxidized to terephthalonitrile. Aluminum is used as a catalyst. Oxide powder with a small surface area and a particle size of 0.25 to 0.105 mm (60-140 mesh) is used which is impregnated with _{1.3 weight V 2} O ₅ and 8.1 weight Sb ₃ O _3.

The reactor has an inside diameter of 5.1 cm (2 ¹¹ ) and, including the discharge section, a length of 102 cm

^Bathroom original

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(40 "). The feed to the reactor is prior to introduction vaporized into the reactor through a manifold with 97 holes, each 0.76 mm (0.03 ") in diameter λ

The feed rate is 29.5 mol / hour Reaction temperature about 454 ° C, the reaction pressure about 0.35 atmospheres (5 psig), the volume based feed rate about 1100 hours. ' ? and the catalyst bed expansion about 24 #.

Including the circuit of the mononitrile (p-tolunitrile), unreacted p-xylene and nitrogen, the composition of the total vapor feed to the reactor in mol- ^ is about 2.5 i> p-xylene + mononitrile, 1.3 * » H ₂ O, 14.0 % NH ₅ and 82.2 1 ° oxygen + nitrogen (of which 8.3 volume- ^ oxygen), ammonia, xylene and air are added to the circulating substances to the extent necessary to form the above-mentioned total soles

kung is required.

During the reaction, about 50 pounds of the xylenes are used per pass implemented. The reaction mixture is out of the reactor peeled off and cooled to about 65 ° C,

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The kondenaierte Prodakt beetoht, Dezogön on Holm Engen, aue about 29.0 <Terephtalonitril, about 38.0 # p-tolunitrile, about 3.2 '. * Other Stoffeund about 29.8% niehtumgesetstera p-xylene.

The condensate is distilled in a first distillation stage., p-xylene and p-tolunitrile are drawn off overhead and with part of the nitrogen in the ammooxidation returned.

The crude terephthalonitrile is at atmospheric pressure and one Distilled overhead temperature of about 285 ° G ,,, and ferephthalo-

nitrile is deducted as product \ X ^ qt head

The total yield of terephthalonttrile is £ 90 based on the net amount of p-xylene added to the system.

Daa 'sicfh easily tibet lead as product TerephtlsalOßitril gained lä0t in high purity Terephtaleäure, aB by Brwaraen ■ it wäesrigea ITatriumhydroxyd sum Röckfluß while removing clay ammonia ₉ uaä anschlieaendee Aneäuern, beiepielaweiee with T © rdünnter ₉ wßesriger Schwefeleäure *

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Example 2

The procedure of Example 1 is repeated with the exception gets that o-xylene is converted into laophthalonitrile. Ee are.equivalent results obtained.

Example ft

The procedure of Example 1 is repeated with the exception that p-ethylbenzene is converted into TerephthalonltriX with equivalent results "

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Claims (1)

ν η * λ. η * a η a ψ τ Ü eh · . 1 “Process for the production of aromatic polynitriles by ammoxidation of aromatic polyalkyl hydrocarbons, characterized in that the reaction is carried out continuously in contact with a fluidized bed of solid catalyst, the conversion of hydrocarbons per pass is in the range of 20 to 80 $ and If hydrocarbons that have not been converted into the water and mononitrile formed during a previous heating process are continuously fed back into the ammoxydation reaction » 2o "method according to claim T, characterized in» that nan P-xylene or m-xylene are all used ataagangsraaterial. 5. The method according to claim 1, characterized in that a conversion per pass in the range of 30 to 60 ^ maintains «, 4, method according to claim 1, characterized in that one a total filling used for the oxidation, the Contains up to 15 mol? s of water vapor. 5 * Method according to claim 4, characterized in that one uses a total deficit which is 0.5 to 2.5 ttol- «i contains water vapor » 009883 / 2T42