JPS63146847A - Improved method for preparing long chain alkylamine and dimethylalkylamine from ester - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for the direct synthesis of aliphatic amines from fatty acid esters by the action of ammonia and hydrogen in the presence of a mixed dehydration/hydrogenation catalyst, in particular: This invention relates to a method for synthesizing dimethylated primary or tertiary amines with high selectivity.

Conventional Technology The most commonly used industrial method for the production of long-chain amines, i.e. amines whose molecules contain 10 to 24 carbon atoms, mainly produces nitriles by reacting fatty acids with ammonia. , is based on a long-known reaction in which the nitrile thus produced is dehydrated and then hydrogenated. Dimethylalkylamine can be produced from the long-chain primary amine thus obtained by various methods. Of these methods, the oldest known one is probably
This is dimethylation of formic acid/formaldehyde based on the (Leuckart) reaction (for example, US Pat. No. 2,366,534). The most widely used method is the reaction of methanol or formalin in the presence of hydrogen.

Furthermore, a method for obtaining aliphatic alkylamine from fatty acids is known. The process is carried out in one step and consists of a metal catalyst, in particular zinc-chromium or zinc-aluminum (French Patent No. 1.549.655), nickel and various promoters (for example German Democratic Republic Patent No. 11
0.487) or by reacting hydrogen with ammonia or amines in the presence of a catalyst based on metal sulphides (UK Patent No. 1.135.915).

In addition, some prior art techniques involve producing amines using triglycerides as raw materials (German Patent No. 1.288.595, United States Patent No. 3.579.585). Methods using esters as raw materials for synthesizing amines are described in particular in French Patent No. 1.598.720, United States Patent No. 2.223.305, and British Patent No. 421.
．． No. 718 can be cited, and these patents propose carrying out the amination reaction with a mixed catalyst containing zinc or alumina as the main components.

Problem to be Solved by the Invention The one-step process from acids, glycerides or esters requires two different steps: dehydration and hydrogenation of the nitrile, and therefore two different catalysts and transfer of intermediate products. There are clear industrial advantages over conventional methods. However, these methods also have various drawbacks, such as: That is, if this process is to be carried out on an industrial scale, it must be operated at high temperatures, generally at hydrogen pressures of 200 bar or more. In addition, selectivity is poor. That is, in addition to the target alkylamine, secondary products are produced that are difficult to remove by conventional separation methods such as distillation.

Means to solve problems The present invention solves these drawbacks.

The process according to the invention makes it possible to obtain long-chain alkyl amines in very good yields and with excellent selectivity in only one step. This process involves dehydration at temperatures in any case below 300°C and under pressures ranging from 50 to 100 bar.
It consists of reacting long-chain fatty acid esters with ammonia, hydrogen and, if necessary, other reagents to improve the selectivity of the reaction, in the presence of a hydrogenation-type mixed catalyst.

The long-chain fatty acid esters mentioned above are methyl esters of fatty acids containing 10 to 24 carbon atoms, more specifically of industrial fatty acids made from tallow, olein, oilseed rape, cabbage palm or cobra, etc. Ethyl ester, propyl ester or butyl ester. Preferred are methyl esters, which are usually liquids and are easily handled industrially and at industrial quantities by metathurisis of fatty substances.

Catalysts useful in this invention include a metal and an acid that also serves as a support.
It is a dehydration-hydrogenation catalyst in combination with a base oxide. Many catalysts of this type are known, such as combinations of noble metals, nickel, cobalt, etc., with alumina, zinc oxide, chromium oxide, etc. The applicant has discovered that in combinations of titanium oxide with copper and cobalt, in particular with copper and chromium and cobalt, during the conversion of long-chain carboxylic acid methyl esters to the corresponding primary amines or dimethylamines, We have discovered a catalyst with high activity and extremely high selectivity.

The catalyst of the invention allows the reaction to be carried out at pressure conditions in the range from 20 to 150 bar, preferably from 50 to 100 bar, which are considerably lower than the conditions of the prior art.

This helps reduce the production of heavy by-products such as dialkylamines. These catalysts contain from 2 to 80% by weight of metals (where "metals" include copper, cobalt,
It is understandable that it refers to chromium. This definition is as follows:
(similarly applicable), more preferably 10 to 50% by weight
including.

Here, cobalt accounts for 2 to 30% of the total active metals. The preferred content is 10%. In ternary systems containing chromium, the proportion of this metal can vary within a very wide range and can be from 1 to 50% of the metal part.

methanol is introduced into the reaction medium and chromium is added from 10 to 2
By using a catalyst containing 5%, preferably its content is about 20%, the reaction can be directed to the production of dimethylalkylamine only.

In order to direct the reaction to the production of only primary amines, less methanol is used and catalysts with a lower chromium content of 0.5 to 15%, preferably 1 to 1.5%, are used. .

These catalysts are obtained by impregnating, precipitating or coprecipitating a metal in the form of a water-soluble salt onto a carrier. In the production method by impregnation, titanium oxide is suspended in water, and the metal salt is added therein either as is or in the form of an aqueous solution. Evaporate all liquid components and heat the powder in a thermostatic oven for about 100 ml.
Air dry at ~150°C, then approximately 350°C in air
Calculate it.

As a result, a "pre-catalyst" is produced. This is a product in storable form and must be activated in a reactor. In the precipitation method, a paste of titanium oxide containing a catalytically active metal salt is prepared as described above and the hydroxide is precipitated from this paste with ammonia at a temperature of about 60 to 80° C. and a maximum pH of 7 to 8. The solid is recovered by filtration, then dried and calcined as in the impregnation preparation described above.

A laboratory implementation of the invention is described below.

This embodiment can be transferred to an industrial scale without any adjustments other than being handled by someone familiar with the materials.

There are some common elements in the following examples regarding catalyst activation and operation of the so-called synthesis reactor. This will be explained below.

The capacity for continuous operation under pressure is approximately 200
- The reaction is carried out in a fixed bed reactor.

After charging the precatalyst, at atmospheric pressure and room temperature, the
Sweep with nitrogen at a rate of h.

Subsequently, nitrogen is replaced with hydrogen and the temperature is gradually increased at a rate of about 0.degree. C./min to the desired reaction temperature. This temperature condition is maintained for approximately 12 hours.

Subsequently, the temperature is adjusted to the desired temperature (250 to 350° C., depending on the reaction) and the pressure is increased to about 50 bar.

Estenopemethanol (if necessary) and liquid ammonia are then introduced, each via a different membrane pump. The feed rate is ester/ammonia/hydrogen ratio 1/10 under standard conditions for the production of primary alkyl amines.
/100, and the standard conditions for the production of dimethylalkylamine are such that the ester/methanol/ammonia/hydrogen ratio is 1/40/10/100, and the space velocity of the reaction mixture (1 ml of catalyst and 1 ml of catalyst) mj2) per hour is controlled to be approximately 1/3 h-'.

These conditions are indicative and can be adjusted to a large extent to take into account the unique conditions of each reaction.

The gas-liquid mixture produced from the reactor is fractionated, the liquid fraction is recovered, and the gas is removed or recycled. The composition of the reaction product is obtained by gas phase chromatography analysis. The optimal conditions are as follows.

-Carbowax (['arbowax) 20 M
(Johns Manville)
Chromosolve WAW (John Manpil Corp.) impregnated with caustic potash (2%)
Column packed with Manville Corp, )) - carrier gas nitrogen (30 m7!/min) - furnace temperature 2
25°C Standardization and reaction balances are performed using aniline as an internal standard. The method is suitable both for synthesis in closed reactors and for continuous synthesis in fixed bed reactors. In the latter case, the unconverted gas obtained by fractionating the mixture produced in the reactor is recycled.

The invention will be made clearer by the following example of the synthesis of dodecylamine or dimethyldodecylamine from methyl dodecanoate.

However, the scope of the present invention is not limited to the conversion of only this raw material.

Example 1 A product with a composition of Cu/obtained by impregnating alumina with copper nitrate
A1203 = 9.1/90.9% catalyst is used.

The molar ratio of ester/ammonia/hydrogen is 1/10/1
00, the reaction space velocity is 0.33h-' and the temperature is 300℃.
Carry out the reaction. As shown in the balance of the composition of the effluent below, conversion occurs completely, but the selectivity is not good.

Dodecylamine 72.0% N-methyldodecylamine 16.0% N,N-dimethyldodecylamine 2.5% Dodecylamide
8.0% dodecylnitrile
1.0% other
0.5% Example 2 Directing the reaction toward the production of dimethylamine using a methanol-containing reactant stream increases the rate of tertiary amine, but the selectivity is still poor.

This means that the ester/methanol/ammonia/hydrogen ratio is 1/40/10/100 and the space velocity is 0.
17h-', at a temperature of 250 degrees, Cu/A1203
The following composition of the effluent obtained for catalyst = 17.8/82.2% is shown.

Dodecylamine 29.2%N-
Methyldodecylamine 34.7%N, N
-Dimethyldodecylamine 15.6% Dodecylamide 9.1% Dodecylnitrile
11.4% Example 3 A catalyst with Cu/Zn0=9/91 is synthesized under the conditions of Example 1. The ester is converted at a rate of 90%. The composition of the converted fraction is as follows.

Dodecylamine 75.0%N-methyldodecylamine 6.7%N,N-dimethyldodecylamine 1.5%dodecylamide
14.0% dodecylnitrile
2.5% other amines
With this composition of 0.3%, the yield of primary amine is poor, especially since amide is formed.

Example 4 Expecting a high yield of primary amines, the composition was Cu/
A chromium-copper type catalyst with Cr2O3=40/60 was operated under the conditions of Example 10. However, the temperature is 300℃ and 35℃.
It was operated at 0°C.

The composition balance according to the number of parts of the effluent corresponding to the ester actually converted is shown in the table below.

In these two cases, the conversion reaches 95% and 100%, respectively, but the selectivity is low or very mediocre.

Example 5 In this example, hydrogen/ester ratios of 100 and 40
00C under almost the same conditions as Example 2 for two cases.
An attempt was made to obtain dimethyldodecylamine by operating on a catalyst with u /Cr 20 a =40/60.

This copper-chromium oxide combination is important because it increases the yield of methylalkylamine. However, the trade-off is that the amide and dialkylamine contents are unacceptable, and the higher the overall yield of methylamine, the lower the selectivity.

Example 6 Composition Cu/Co/Ti 0 prepared by co-impregnation
The reaction is carried out in the presence of a catalyst of a=20/2.5/77,5. The reaction temperature is 250°C. All other operating conditions are the same as in Example 1. The following were obtained: Nidodecylamine 86.2% N-methyldodecylamine 2.1% N, N-dimethyldodecylamine 0.9% Dodecylamide
(below measurement limit)
Dodecane below measurement limit
1.7% other amines 9
．． 1% Example 7 Composition is Cu/Cr/Co/Ti 02 =20/1.
5/1.5/77, the reaction according to the invention is carried out using a mixed catalyst obtained by co-impregnation with titanium oxide.

The reaction temperature is 250°C. All other conditions are the same as in Example 1. What was obtained is as follows.

Dodecylamine 83.0%N-
Methyldodecylamine 4.1%N, N
-dimethyldodecylamine 0.5% dodecylamide 1.0% dodecylnitrile
0.7% dodecane
8.0% other amines
2.7% Example 8 Weight composition is Cu/Cr/Co/Tie, =15.1/
1.1/2.6/81.2 and prepared by physically mixing a catalyst impregnated with Co/T102 and Cu/Cr/Ti02, the reaction according to the invention is carried out.

The effluent was Nidodecylamine 74.5% N- with the following composition:
Methyldodecylamine 1.0%N,N-dimethyldodecylamine 1.0%Dodecylamide
1.0% dodecylnitrile
1.0% dodecane
16.4% other' amines
5.1% In this example, as in Examples 6 and 7, almost all of the ester can be converted by the combination of titanium oxide and the metal composition of copper-cobalt or copper-chromium-cobalt. It was found that long-chain alkylamines containing almost no converted congeners were formed. Hydrocarbons constitute a significant portion of the by-products of the reaction. Generally, hydrocarbons do not interfere with the subsequent use of the primary amine and are easily separated.

Example 9 In this example, dimethylalkylamine was prepared using a methanol-containing effluent using the catalyst of the present invention, which is mainly composed of titanium oxide and a chromium-rich ternary system Cu/Cr/Co. Carry out the reaction.

At this time, the weight composition of the catalyst is T102/Cu/Cr/C
o=55.6/22.1/20.1/2.2. The reaction conditions are an ester/methanol/ammonia/hydrogen ratio of 1/40/10/400, a temperature of 250°C, and a space velocity of 0.33 h-'. In this way, almost all the ester can be converted to dimethyldodecylamine. The composition of the effluent is as follows: N-methyldodecylamine 4% N,N-dimethyldodecylamine 93% dodecylamine
1.5% dodecylamide
0.5% Dodecylnitrile Below measurement limits Other amines Below measurement limits Dodecane 1% Patent Applicant Seka Nis, Ar.

Claims (9)

[Claims] (1) Combining a long chain carboxylic ester with a stream containing ammonia and hydrogen in the presence of a mixed oxide-metal type catalyst.
10 to 24, consisting of reacting in only one step
A method for producing primary alkyl amines and dimethylalkylamines having an alkyl chain composed of hydrocarbon residues containing 5 carbon atoms, wherein the catalyst comprises titanium oxide and copper or cobalt in combination with cobalt. a combination of copper and chromium. 2. Process according to claim 1, characterized in that said catalyst contains from 2 to 80% by weight of a metal from the group consisting of copper, chromium and cobalt. (3) A method according to claim 1 or 2, characterized in that said catalyst contains 10 to 50% by weight of a metal from the group consisting of copper, chromium, and cobalt. (4) The method according to any one of claims 1 to 3, wherein the long-chain carboxylic acid ester is a methyl ester. (5) The above reactant stream contains methanol in addition to ammonia and hydrogen, and the weight proportion of chromium in the above catalyst is 1.
Process according to claim 4, preferred for the production of dimethylalkylamines, characterized in that the content is between 0 and 25%. (6) Claims preferred for the production of monoalkylamines, characterized in that said stream contains ammonia and hydrogen in addition to methanol, and the weight proportion of chromium in said catalyst is from 0.5 to 15%. The method described in paragraph 4. (7) by reacting a long-chain carboxylic ester characterized by containing titanium oxide, copper, chromium, and cobalt with a stream containing ammonia and hydrogen.
Oxide-metal type catalysts for the production of primary alkylamines and dimethylalkylamines having a hydrocarbon chain containing 24 carbon atoms from (8) The catalyst according to claim 7, which contains 2 to 80% by weight of copper, chromium, and cobalt. (9) The catalyst according to claim 8, which contains 1 to 25% by weight of chromium.