DE3048836A1 - "METHOD FOR PRODUCING POLYAMINES" - Google Patents

Description

Process for the production of polyamines

The present invention relates to a method of manufacture of polyamines from polynitriles using a hydrogenation catalyst in pellet form.

It has been found that many pelletized hydrogenation catalysts like cobalt and nickel in the hydrogenation of polynitriles to the corresponding polyamines for disintegration tend. During the hydrogenation it is observed that the catalyst pellets either swell or become fine particles disintegrate or that both occur at the same time. Loss of physical durability affects utility the catalyst pellets in terms of precise control, especially in continuous operation, with such variables as space velocities etc. carefully selected and need to be controlled. In particular, see. Channels in the catalyst bed so that there is insufficient contact of Nitrile takes place with the catalyst. Continue to clog sometimes the fine particles enter the reactor or the reactor pipes.

Γη U.S. Patent No. 3,384,666 describes a method for preventing the disintegration of the catalyst pellets. This method essentially involves the use of sodium, potassium or lithium hydroxide or alkoxide. While the use of alkaline stabilizers has been found to be effective, there have been certain disadvantages. For example, it was found that if such a method is used effectively, the etchant neutralizes and the

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steliende salt must be filtered off. This means of course a time consuming and relatively expensive extra step. It was also found that the base with those nitriles which contain an additional oxy group reacts in such a way that the desired amine is not obtained. This means that undesirable side reactions occur.

Other ways of maintaining the durability of hydrogenation catalyst pellets have also been discovered. In some cases amine-like stabilizers are also used. Although when using such stabilizers the above with reference Problems listed on stabilizers are avoided, they also lead to increased costs for the entire process, because another additive has to be used in catalysis.

U.S. Patents 3,427,356, 3,728,284, and 4,07,226 other solutions to the above problem are suggested.

It would therefore be a significant advance in this area if a catalyst suitable for the hydrogenation of polynitriles would be found which does not disintegrate or crumble during catalysis, but in which the pellet shape of the Catalyst is retained without the need for additional chemicals.

to provide such a catalyst, a method for Hydrogenation of polynitriles to polyamines developed. In the broadest sense, the invention includes the use of a too Pellet shaped cobalt-zinc hydrogenation catalyst, usually in the oxide form, which is distinguished by the retention of the pellet form during the hydrogenation without application

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the addition of additional stabilizers,

The hydrogenation process for the production of polyamines from Contains polynitriles by the process of the invention specifically the hydrogenation of the polynitrile in the presence of a cobalt-zinc hydrogenation catalyst in pellet form.

The hydrogenation itself can be carried out in the presence or in the absence of a solvent. Fird a solvent applied, it is preferably an organic solvent such as an alcohol. Typical suitable alcohols are Methanol, ethanol, isopropanol, t-butanol, n-propanol and other alcohols, but especially alcohols which are miscible with water.

The polynitriles useful in the present invention can be made from a variety of known materials Type can be selected. Preference is given to di- and trinitriles, which are obtained by reacting acrylonitrile with an amine, polyamine, Polyhydroxymonoamine, polyhydroxypolyamine, such as ammonia, methylamine, piperazine, ethylenediamine, monoethanolamine, diethylenetriamine, 3-aminopropanol, methylethanolamine, aminoethylethanolamine can be produced. Other preferred polynitriles contain an additional oxy group. Typical examples of these oxynitriles are acrylonitrile adducts of Polyols such as ethylene glycol, di- and triethylene glycol, glycerine, trimethylolpropane, 1,4-butanediol, 1,3-butanediol

The pellet catalyst used here is a cobalt-zinc hydrogenation catalyst in pellet form, which usually consists of cobalt and zinc in a molar ratio of 98: 2 to Goiho, based on Co and Zn ^. The metals are usually in the form of oxides.

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The carrier material can be any material that is inert under the process conditions, such as refractory carrier material, charcoal, Silica, alumina and the like which can be used with the active hydrogenation catalysts. the Methods for making such supported catalysts are well known to those skilled in the art.

The hydrogenation can be carried out under a wide range of reaction conditions be performed. The polynitrile is typically in the presence of the catalyst described above Temperatures from about 7o to about 22o C, a pressure of 29 to 785 bar and carried out in the presence of hydrogen. The reaction temperature is preferably 7o-15o C, the pressure is preferably 35-690 bar and particularly preferred at 69 _ 2o8 bar.

In a particularly preferred embodiment, ammonia is also present in the reaction. The ammonia serves to improve the selectivity of the reaction to the primary amine and prevents the bimolecular coupling for the formation of secondary amines, which are usually not desired in the reaction. When ammonia is used, about 2 to about 20 moles of ammonia are usually present per equivalent of nitrile. When hydrogen and ammonia are used together, the partial pressure of the hydrogen is usually 60-80 </ o of the total pressure.

The rough rate of the hydrogenation (g nitrile / h / ml catalyst) is not critical in the process. However, the hydrogenation is preferably carried out at a space velocity of about 0.5 to about 5 S total liquid starting material / h / ml of catalyst.

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3048838

The hydrogenation can be batch or continuous Operation can be carried out, with continuous operation being preferred. In the case of batch operation, a closed Autoclave and a tubular reactor for continuous operation.

The desired polyamine can then by known techniques, such as distillation obtained from the hydrogenation mixture will. Usually the polyamine must be separated from the amine stabilizer by distillation, if the latter is in such Amounts are used that it also acts as a solvent in the hydrogenation.

It should be noted that only in the preparation of polyamines from polynitriles the problem of instability of the catalyst occurs during hydrogenation. Ferden mononitrile hydrogenated, this disadvantage does not arise. Dinitriles like Adipic acid nitrile or phthalic acid nitrile cause Implementation to diamines only minor stability problems of the Catalytic converter. However, di-, tri- or tetranitriles are made from the reaction of acrylonitriles and compounds which react with said acrylonitrile, such as alcohols and amines and hydrogenated, most catalysts such as the cobalt type decompose during hydrogenation.

As just stated and as from the following examples As can be seen, cobalt plague bed catalysts alone are likely to be used to convert polynitriles; Suitable for polyamines, however, their pellets or tablets also disintegrate into fine particles if they are used for a substantial period of time Hydrogenation were used. However, a cobalt-zinc-oxide mixture shows stable pellets, even in the absence of one Caustic or amine stabilizer.

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While the invention related to the use of catalysts has been described in pellet form, it goes without saying that the term "pellet" also includes tablets with such physical Includes forms of cobalt-zinc containing catalysts alternately employed in the present invention can be.

example 1

A solution of 488 g of cobalt nitrate hexahydrate (1.68 mol) and 36 g of zinc nitrate hexahydrate (0.12 mol) in two liters of distilled water was heated to 75.degree. This solution was slowly added to a solution of 197 g of sodium carbonate in three liters of distilled water at 75 ° C. with stirring. After the addition was complete, the slurry was stirred at 80 ° C. for 1 hour and then filtered. The collected solid was washed eight times with two liters of hot distilled water, dried at 110 ° C. and calcined at 400 ° C. for 2 hours. The desired cobalt and zinc oxides (i42 g) contained 66.5% Co, 5.1 ° / o Zn and 513 ppm Na. This product was placed in a glass tube and prereduced with hydrogen at 325 ° C. until moisture could no longer be found in the outlet stream. After the catalyst was cooled to room temperature in situ under nitrogen, it was carefully reoxidized with oxygen in nitrogen. The stabilized cobalt-zinc oxide catalyst was mixed with 0.5 ° / o of graphite before therefrom cylindrical pellets having a diameter of o, were molded cm 32nd

In a 3 liter flask 600 g of ethylenediamine (10.0 mol) were added at 35-5o ° C. and with cooling with 1855 g of acrylonitrile (35.0 mol). After the addition was complete, the solution was placed in a stirred autoclave with 60 g of commercial silicon-aluminum

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oxide catalyst (Aerocat Silica Alunima TA, American Cyanamid Company) and heated to 160 ° C. for k h. This mixture of cyanoethylated ethylenediamines was used as starting material in the experiments described here and in Example 2.

23 ml of the cobalt-zinc-oxide catalyst in pellet form, the preparation of which was described above, was placed in a small fixed bed reactor. A liquid starting mixture consisting of equal amounts of liquid ammonia, methanol and cyanoethylated ethylenediamine with a molar ratio of 3.5 μl was passed over the catalyst at a rate of 24 ml / h. Hydrogen was added at a rate of 12 l / h STP. The pressure was kept at 173 bar, the reactor temperature was 115 C. Samples of the liquid product were taken at intervals and with. Infrared determination of the nitrile examined for the completeness of the reaction. After 53 hours of operation, the catalyst was removed from the reactor; the pellets had not changed. A sample of the liquid product was passed through a thin film evaporator prior to analysis by gas chromatography, it contained 54% tris (aminopropyl) -ethylenediamine and 9 io bis (aminopropyl) -ethylenediamine.

Example 2

In this example a commercial catalyst was prepared made of cobalt, copper and chromium oxide in an atomic ratio of 75: 23: 2. Same plague bed reactor as in Example 1, 25 ml tablets with a diameter of 0.32 cm were filled. Using the same starting material, of the same hydrogen flow, pressure and the same temperature as in Example 1, the test had to be carried out after 20 hours be stopped because the catalyst pellets had completely disintegrated and clogged the reactor.

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Example 3

Commercially produced cobalt in pellets o.32 cm in diameter was placed in a 25 ml plague bed reactor. An acrylonitrile-ethylenediamine reaction product in a molar ratio of 3 »5s1 in a solution of methanol / liquid ammonia / polynitrile in a weight ratio of 1: 1: 1 passed over the catalyst in the presence of hydrogen. There was a relatively good conversion in the hydrogenation except towards the end of the 55 h trial. However, the catalyst pellets had disintegrated into pieces upon removal from the reactor and could no longer be used.

Example k

To a solution of 197 g of sodium carbonate (1.85 mol) in 3 liters of distilled water were added 43o g of cobalt nitrate hexahydrate (1.48 mol) and 1o1 g of zinc nitrate hexahydrate (0.33 mol) in 2 liters at 75 ° C given to distilled water. The mixture was stirred at this temperature for 1 h, then filtered and washed eight times with hot distilled water. The oxides were dried at 11o C and calcined for 2 hours at 4oo C, whereupon 144 g of product being obtained, which contained 56.9 ° / o Co, 12.8 ° / ₀ Zn and 142 ppm Na. This was pre-reduced with hydrogen at 325 C, stabilized in nitrogen with oxygen and processed into pellets with 0.5% graphite. The tablets were placed in the 25 ml fixed-bed reactor and subjected to a continuous test lasting 10 hours. The nitrile used was produced by reacting acrylonitrile with ethylenediamine in a molar ratio of 1.5: 1. A solution consisting of equal parts by weight of nitrile, methanol and anhydrous ammonia was passed over the catalyst at a rate of 2k ml / h in the presence of 12 l / h of hydrogen. The gasChromatograph! See analysis of the

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Meth.an.ol and ammonia liberated product gave 64 ° / o bis (aminopropyl) -ethylenediamine and 33 ° / o Aminopropyläthylendiamin. The catalyst pellets had not changed their shape.

Example 5

This experiment was carried out using that described in Example 2 commercial nitrile hydrogenation catalyst and des same 1.5: 1 acrylonitrile-ethylenediamine reaction product of starting material as in Example 4 carried out. Normally the tendency of the catalyst tablets to disintegrate falls as the ratio of acrylonitrile-ethylenediamine in the starting material decreases. The cobalt-copper-chromium oxide catalyst was used for 85 hours under the same conditions as in Example 4, at the end of the experiment it was almost completely present as finely divided slush.

Example 6

22.6 g of synthetic calcium silicate were heated to 70 ° C. in 2 liters of distilled water. While stirring, 244 g of Co (NO ₃ ) ₂ * 6H ₂ O and 18 g of Zn (NO ₃ J ₂ * 6H ₃ O in 2 liters of distilled water and 155 g of sodium carbonate in 2 liters of distilled drums were slowly added at the same time Maintained 70 ° C., the additions being made in such a way that the pH of the reaction solution did not change.After one hour, the contaminants were filtered off, washed eight times, dried at 110 ° C. and calcined for one hour at 400 ° C. Analysis of the catalyst before prereduction resulted in 51 »3 fo Co, 4.1 % Zn, 4.8 fo Si and 532 ppm Na. After pre-reduction at 325 ° C. and stabilization, pellets were formed with the addition of 0.5% graphite.

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The starting material for the fixed bed hydrogenation was prepared by reacting 1.88 moles of acrylonitrile per mole of ethylenediamine. The continuous experiment was carried out under the same conditions as in Example 1. After 22 h the gasChromatographieehe analysis of the product gave (free of ammonia and methanol) 15 ° / o-aminopropyl ethylenediamine, 69 ° / o bis (Atninopropyl) -ethylenediamine and 7, 6% tris (aminopropyl) -ethylenediamine. The experiment was stopped after 251 h, the corresponding ¥ erte at 15 ° / ° t 9% and 7.3 ° / o lay. The catalyst pellets were not broken into a finely divided material, although some were broken.

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Claims (3)

Texaco Development Corp. T-039 80 DE S / KB D 75,787-F (OLB) claims 1. (Process for the preparation of polyamines from the corresponding Polynitrile in the presence of a shaped, preferably applied to a carrier material Pelleted hydrogenation catalyst, characterized by the reaction in the presence of a cobalt-zinc catalyst. 2. The method according to claim 1, characterized in that a cobalt-zinc catalyst is used wherein the metals are in oxide form. 3. The method according to claim 1 or 2, characterized in that a cobalt-zinc catalyst is used, in which cobalt and zinc are present in a molar ratio of 98: 2 to 60:40. 130041/0827 S>