NL8100034A - PREPARATION OF POLYAMINS FROM POLYNITRILS. - Google Patents

Description

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Short designation: Process for "preparing polyamines from polynitriles.

The invention relates to a process for preparing polyamines from polynitriles using a pellet hydrogenation catalyst.

It has been found that many hydrogenation catalysts in the form of pellets such as cobalt or nickel when used for the hydrogenation of polynitriles to the corresponding polyamines tend to decompose. During the hydrogenation reaction, the catalyst pellets are swollen or disintegrate into fine particles or both phenomena occur. Due to loss of physical integrity, the usefulness of catalyst pellets deteriorates somewhat in terms of suitable control, especially in a continuous process where variables such as space velocity, etc., must be carefully controlled. In particular, channel formation occurs in the catalyst bed, so that there is no proper contact of nitrile and catalyst. Fine particles also sometimes clog the reactor or the reactor lines.

U.S. Pat. No. 3,584,666 describes a method of preventing catalyst pellet disintegration. This method essentially involves the use of a sodium, lithium or potassium hydroxide or alkoxy base.

While such appropriate use of strong basic stabilizers has been found effective, it has nevertheless been found later that such use has certain drawbacks.

For example, it has been found that such an efficient working method should include neutralizing the strong base and filtering off the salt.

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This, of course, means a time-consuming, and relatively expensive additional stage. In addition, it was discovered that the strongly basic substance reacts with those nitriles, which also contain an oxy group, that the desired amine is not obtained. This means that unwanted side reactions occur.

Other means of maintaining the integrity of hydrogenation catalysts have been discovered. In some cases this includes the use of an amine type stabilizer. However, while resorting to such a stabilizer avoids the problems described above with regard to the use of the highly alkaline substance, this use nevertheless adds "necessarily increasing costs to the overall process with respect to the necessary use of another chemical additive in catalysis.

Still other proposed solutions to the said problem are set forth in U.S. Pat. Nos. 3,427,356; 5,728,284; and 4 * 007,226.

It would therefore represent a significant advance in the art if one discovered a special type of catalyst useful for the hydrogenation of polynitrilea, which would show no disintegration or deterioration during catalysis, thereby maintaining the catalyst pellet shape, yet no refuge until the additional use of protective chemicals needs to be taken.

In accordance with the invention, a process for hydrogenating polynitriles to polyamines was discovered. The invention includes the use of a cobalt-zinc hydrogenation catalyst in pellet form, usually in oxide form, which is characterized in that it maintains its integral character during this hydrogenation without resorting to inorganic or organic stabilizers.

More in detail, the hydrogenation technique of preparing polyamines from polynitriles by the method of the invention includes hydrogenation of the polynitrile in the presence of a cobalt-zinc pellet hydrogenation catalyst.

The hydrogenation reaction itself can be carried out in the presence of 8100034-3 * in the absence of a solvent. When a solvent is used, it is preferred that an organic solvent such as an alcohol is used.

Typical useful alcohols include methanol, ethanol, isopropanol, t-butanol, n-propyl alcohol, or other alcohols, especially water-miscible alcohols.

The polynitrile to be treated according to the invention can be selected from a wide variety of known materials of this type. Preference is given to di- and tri-nitriles. prepared by reacting acrylonitrile with an amine, polyamine, polyhydrozymonoamine, polyhydroxypolyamine, etc., such as ammonia, methylamine, piperazine, ethylenediamine, monoethanolamine, diethylenetriamine, 3-aminopropanol, methylethylamine, aminoethylethanolamine, etc. polynitriles 15 are those which also contain an oxy group. Typically, these oxynitriles include, for example, acrylonitrile adducts. of polyols such as ethylene glycol, di- and triethylene glycol, glycerol, trimethylolpropane, butane-1,4-diol, butane-1,3-diol, etc.

The pelletized catalyst used in the process of the invention is a pelletized cobalt-zinc hydrogenation catalyst usually consisting of cobalt and zinc in molecular ratios ranging from 98 s 2 to 60: 4-0 expressed as Co and Zn. The metals are usually used in oxide form.

The support used can be any support that is inert to the process conditions, such as refractory support, charcoal, silica, alumina and the like which are capable of being used with the active hydrogenation catalysts.

The methods of preparing such catalysts on supports are well known.

The hydrogenation reaction itself can be conducted in a wide range of conditions. The polynitrile is typically hydrogenated in the presence of a catalyst of the described class at a temperature within the range of about 70 ° to about 220 ° C and at a pressure of about 30-80 atmospheres in the presence of hydrogen. The reaction temperature is more preferably 70-150 ° C with a pressure of Tij preferably 34 to 680 atmospheres and most preferably 68 to 204 8100034 * + 4 atmospheres.

In a highly preferred embodiment, ammonia is also present during the reaction. The ammonia aids the reaction by promoting better selectivity to the primary amine, and prevents that molecular coupling from producing secondary amine formation, which is usually undesirable in the reaction. When ammonia is present, usually about 2 to about 20 molecules of ammonia per equivalent of nitrile are present. When hydrogen and ammonia are used together, the partial hydrogen pressure will usually be from about 60 to about 80 fo of the total pressure.

The special space velocity of the hydrogenation reaction (grams of nitrile / hour / cc of catalyst) is not critical in the process. However, it is preferred to carry out the hydrogenation reaction at a rate of from about 0.5 to about 5 grams of total liquid feed / hour / cc of catalyst.

The hydrogenation reaction can be carried out here batchwise or continuously, with continuous operation being preferred. Suitable reactors for this include both a closed batch autoclave for the batch process, or a tubular reactor capable of continuous operation.

The desired polyamine product can then be recovered from the hydrogenation reaction medium by any of the methods known in the art, such as by distillation. Thus, usually, the polyamine product must be separated from the amine stabilizer by distillation when the latter is used in amounts such that it also acts as a solvent for the hydrogenation reaction.

It is interesting to note that only when polyamines are derived from polynitriles does the problem of catalyst stability arise during the hydrogenation step. Mononitriles when hydrogenated are not at all subject to this drawback. Even those nitriles such as adiponitrile or phthalonitrile, when converted to amines, will cause only minimal catalyst stability problems.

However, when di-, tri- or tetranitriles - derived from the reaction of acrylonitrile and compounds reactive therewith, such as alcohols and amines, are hydrogenated, the 8100034

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Most catalysts such as the kohalt type are physically degraded during the hydrogenation reaction.

Furthermore, as already stated and as will become more apparent from the examples, that fixed bed cobalt catalysts alone, although useful for converting polynitrials to polyamines, are certainly insufficient because the pellets or tablets are converted into fine products. they are used in the hydrogenation process for a considerable time.

Still, a cobalt-zinc oxide mixture is stable in being able to maintain the pellet shape even in the absence of a highly alkaline or an amine stabilizing additive.

While the invention has been described in terms of the use of pelletized catalysts, it is understood that the term "pellet" also includes tablets or other shaped articles having such a physical form of the cobalt-zinc containing catalyst that it is useful in the process according to the invention.

Example I

A 488 g solution. (1.68 mill) cobalt nitrate hexa hydrate and 36 g. zinc nitrate hexahydrate (0.12 mol) in two liters of distilled water was heated to 75 ° C. This solution was slowly added with stirring to 197 gm (t 85 moles) of sodium carbonate in three liters of distilled water, also at 75 ° C. After the addition was complete, the suspension was stirred for an additional hour at 80 ° C and then filtered. The collected solids were washed eight times with two liters of warm distilled water, dried at 110 ° C and calcined at 400 ° C for two hours. The mixed cobalt and zinc oxides, weight 142 g, contain 66.5% Co, 5.1 ° Zn and 515 PPm sodium. This product was placed in a glass tube and pre-reduced with hydrogen at 325 ° C until no more moisture was observed in the exhaust gases. After the catalyst was cooled to room temperature under nitrogen in situ, it was carefully re-redyzed with dilute oxygen in nitrogen. The stabilized cobalt-zinc oxide catalyst was mixed with 0.5% graphite before it was formed into 0.32 cm diameter cylindrical pellets.

To a three liter bottle containing 600 g (10.0 moles) ethylene diamine, 1855 3 · (35.0 moles) acrylonitrile was added at 35-50 ° C under external cooling. After the addition 8100034 * · r> - 6 - was completed, the solution was placed in a stirred autoclave with 60 g. commercial silica, alumina catalyst (Aerocat Silica

Altunina TA, American Cyanamid Company) and heated at 160C for four hours. This mixture of cyanoethylated ethylenediamines 5 was used as a feed in the experiments described here in Example II.

25 $ 11. pellets of the cobalt-zinc oxide catalyst the preparation of which has been described above were placed in a small fixed bed reactor. A liquid feed consisting of equal 10 weight amounts of liquid ammonia, methanol and the 3.5 / 1 mole ratio of cyanoethylated ethylenediamine were passed upward through the catalyst at a rate of 24 m / h. Hydrogen was also introduced at a rate of 12 liters / hour STP. The pressure was kept at 170 atmospheres and the reactor temperature at 115 ° C. Samples of the liquid product were collected periodically and analyzed for the completeness of the reaction for infrared nitrile determination. After 53 hours of operation, the catalyst was removed from the reactor and the pellets were found to be unchanged in appearance. A sample of liquid product was passed through a wiped film evaporator before analysis by gas column and contained 54 tris (aminopropyl) ethylene diamine and 9 bis (aminopropyl) ethylene diamine.

Example II

A commercial catalyst prepared from a 75 * 23 * 2 atomic-25 ratio of cobalt, copper and chromia was used in this experiment. The same fixed bed reactor as used in Example I was charged with 25 ml. tablets with a diameter of 0.32 cm.

Using the same power supply, hydrogen flow, pressure and tempera! As in Example 1, the test was terminated after 20 hours because the catalyst pellets had completely disintegrated and the reactor was stopped. «

Example III

0.32 cm diameter cobalt pellets were placed in a fixed bed catalytic reactor with a capacity of 25 ml. An acrylonitrite ethylene diamine reaction product having a molecular ratio of 3/5 / l in a 1: 1: 1 weight ratio methanol-liquid ammonia-polynitrils solution was passed over the catalyst with hydrogen to give a relatively high 8100034 r / T-7 - conversion to hydrogenation except near the end of the 55-hour test. However, when removed from the reactor, the catalyst was found to be broken pieces of the tablet and no longer capable of further use.

5 Example 17

450 g were added to a solution of 197 S (1 * 85 moles) of sodium carbonate in 3 liters of distilled water. (1.48 mill) cobalt nitrate hexahydrate and 101 g. (0.34 mol) zinc nitrate hexa hydrate in 2 liters of distilled water at 75 ° C. Stirring was continued at that temperature for one hour followed by filtration and washing eight times with warm distilled water.

The oxides were dried at 110 ° C and calcined at 144 ° C for 2 hours at 400 ° C. 56.9 ° C, 12.8% Zn, 142 ppm sodium. It was pre-reduced with hydrogen at 325 ° C, stabilized with dilute oxygen in nitrogen and pelleted with 0.5 ° graphite. The tablets were placed in the 25 ml fixed bed reactor and subjected to a 101 hour continuous operation. The nitrile wax used was prepared by reacting acrylonitrile with ethylenediamine in a 1.5: 1 molar ratio.

It was passed over the catalyst in a solution consisting of equal proportions by weight of nitrile e, methanol and anhydrous ammonia in an amount of 24 ml. per hour together with 12 liters (SH?) per hour of hydrogen. Gas chromatographic analysis of the product, free from methanol and ammonia, gave values of 64% 25 bis (aminopropyl) ethylenediamine and 35% aminoprolyl ethylene diamine.

The catalytic pellets were physically unchanged.

Example 7. Here, an experiment was conducted using the commercial nitrile hydrogenation catalyst described in Example II and the same 1.5: 1 mol ratio of acrylonitrile ethylenediamine addition product feed of Example IY. Normally, as the acrylonitrile ethylene diamine ratio in the feed used is reduced, the tendency of the catalyst tablets to decompose decreases. Under the same conditions as used in Example IY, the cobalt-copper-cromia catalyst was used for 85 hours, and was converted to finely divided mud at the end of the experiment.

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Example 71

Two liters of distilled water containing 22.6 g. synthetic calcium silicate was heated to 70 ° C. This was stirred while 244 [Co (N0j) 2.6] 20 and 18 g. Zn (NO) 2.6H 2 O in two liters of distilled water were slowly supplied along with 155 S sodium bicarbonate in another two liters of distilled water.

All solutions were kept at 70 ° C, with the additives adjusted to maintain the pH of the reaction solution at 7.0.

After an hour digestion period, solids were collected by filtration, washed eight times, dried at 110 ° C, and calcined at 400 ° C for one hour. Analysis of the catalyst for the pre-reduction was Go 51 »5 Zn 4» 1 f ° t Ca 5 »7 Si 4.8 fo and Na 532 ppm. After pre-reduction at 325 ° C and stabilization, pellets were prepared using 0.5% graphite.

The fixed bed hydrogenation feed was prepared by reacting 1.88 moles of acrylonitrile per mole of ethylenediamine.

The continuous run was run at the same rates and conditions as in Example 1. After 22 hours, the gas chromatographic analysis of the product (free from ammonia and methanol) was 15 ° aminopropylethylenediamine, 69% bis (aminopropyl) ethylene-20 diamine, and 7.6 ia tris (aminopropyl) ethylenediamine. The experiment was terminated after 251 hours at which time the corresponding analyzes were 15 µl, 69 µl and 7.3 µl. The catalyst pellets did not form a finely divided material or just some of the pellets were split.

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Claims (6)

A process for the preparation of a polyamine by hydrogenation of a corresponding polynitrile presence of a catalyst, characterized in that the catalyst is a cobalt-2 ink hydrogenation catalyst in pellet form. 2. Process according to claim 1, characterized in that the hydrogenation is carried out in the presence of a solvent. 5. Process according to claim 1 or 2, characterized in that the liquid phase hydrogenation is carried out at a temperature of 70-220 ° C and a pressure of 30-800 atmospheres. Process according to claims 1-3, characterized in that the hydrogenation is carried out in the presence of ammonia. 5. Process according to claims 1-4, characterized in that the catalyst contains cobalt and zinc metal in oxide form. 6. Process according to claims 1-5 », characterized in that the polynifail has been obtained by reacting acrylonitrile with an active hydrogen compound. 8100034