DD144167A1 - PROCESS FOR THE PREPARATION OF ALIPHATIC PRIMARY AMINES - Google Patents

Abstract

The invention relates to a process for the preparation aliphatic primary amines by catalytic hydrogenation of Fatty acid nitriles having 5 to 22 carbon atoms with hydrogen, 3 to 30 vol .-% ammonia mixed, using known catalysts and under known conditions. The goal of Invention, increasing the yield of primary amine to at least 95% while reducing the specific Catalyst consumption is on an industrial scale by admixture from 5 to 30% by volume of nitrogen to the hydrogen / ammonia gas mixture reached.

Description

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Title of the invention

Process for the preparation of aliphatic primary amines

Field of application of the invention

The process according to the invention can be used in the preparation of aliphatic primary amines, which are important starting materials for versatile cationic compounds. Amines of this type are also valuable auxiliaries in various industries, such as, for example, potash mining, the fertilizer industry, the corrosion protection sector and road construction.

Characteristic of the known technical solutions

Numerous processes are known for the preparation of primary amines, which proceed for the most part from fatty acid nitriles. The reaction of the nitriles with hydrogen takes place on hydrogenating catalysts at elevated pressures and temperatures.

In the case of uncontrolled catalytic hydrogenation, considerable amounts of secondary and tertiary amines are formed in addition to the desired primary amines. Therefore, numerous measures have been proposed for the preferred formation of primary amines, of which the hydrogenation in the presence of ammonia is used on an industrial scale (Houben-Ny. Weyl, Stuttgart 1957, Vol. 11/1, p. 34-6). Hydrogen-ammonia gas mixtures with ammonia contents of between 3 and 30% by weight are used in accordance with DAS 1 198 373, DD-PS 110 et al Procedures reach primary amine levels of about 90 % »

Except by the addition of ammonia is the achievement of high Primäramingehalte according to R, Schröter, Houben-Weyl, Stuttgart 1957, Volume 11/1, S »3 ^ -9 by the presence of strongly basic compounds, preferably sodium hydroxide or alkali-containing / catalysts,

such as Raney nickel, possible »

As catalysts, all customary hydrogenation catalysts are known to be suitable, with preference being given to nickel, cobalt, zinc, chromium catalysts or mixtures thereof for industrial use.

To ensure the economics of the particular catalytic process, besides selecting a catalyst suitable for the preferred primary amine formation, it is important to establish reaction conditions in which the most expensive catalyst retains high efficiency over a long period of time. Since catalysts giving a high yield of primary amines, 'are sensitive to impurities in the starting product en weniger.selektive as catalysts, according THE ι has been tried 543? 62, ⁵ by alkaline pretreatment of fatty acid, a high yield of primary amines to while reducing catalyst consumption. Despite the elaborate technological pretreatment of the. Ednsatznitrils is a catalyst consumption of 0.2 % Raney nickel, based on the Einsatznitrilmenge, ¹ not below. To preserve the efficacy of a nickel on SiOP catalyst, according DAS 1 -198373 the hydrogenation mixture a polar adsorbent ¹ is preferably alumina, is added to obtain a catalyst consumption wirdo indicated by 2% with the same procedure will be for Raney nickel using values of 0, 4 to 1% indicated. About the catalyst consumption at a constant high Primäramingehalten in the catalytic conversion of long-chain fatty acid nitriles, ^1, for example, on fixed catalysts, no exact information is known from the literature.

Object of the invention

The aim of the invention is a process for the preparation of aliphatic primary amines from fatty acid nitriles having 5 to 22 hydrocarbon atoms, ¹ which allows to obtain reproducibly high yields of primary amines with substantial reduction of the catalyst consumption ».

Explanation of the essence of the invention

The processes for the preparation of primary amines by catalytic conversion of fatty acid nitriles with ammonia-added hydrogen at elevated temperatures and pressures do not necessarily lead to high primary amine contents in the reaction product, but due to concurrent parallel and secondary reactions u, a · Also for the formation of unwanted secondary and tertiary amines «All already pointed out proposals for the suppression of side reactions are associated with additional expenditure and still did not lead to the desired results, The economic goal to obtain consistently high Priraäramingehalte with minimal catalyst consumption, by the known methods only partially fulfilled · Either results in a minimized catalyst consumption with technologically unavoidable

Fluctuations in the Reaction Procedure Immediately Variations in the End Product Quality or Increased Catalyst Use Necessary for Achieving Reproducibly High Primary Amine Deteriorates the Efficiency of the Process The resulting requirement for reuse of the catalyst or prolongation of service life for fixed bed catalysts is contrary to prior art experience the lifetime of the catalyst is severely limited by so-called poisoning effects during catalytic conversion «

It has been found that compared to the prior art far better results are achieved by carrying out the catalytic conversion of aliphatic nitriles having 5 to 22 Kohlenwasserstoffatomen.unter known conditions with a 3 to 30 vol .-% ammonia-containing hydrogen, the 5 bis 30 vol .-% nitrogen are mixed. _: ... /.

As a result of the better selectivity of the reaction of the nitriles with hydrogen gelj ^ gt.fes »achieved at the same time reduced catalyst consumption and a virtually 100% degree of conversion, while suppressing the side reactions to increase the formation of primary amines significantly«

Surprisingly, in spite of lowering the hydrogen partial pressure contrary to known experience hydrogenation, which selectively and in the technical process reproducibly to primary.en amine contents of average 95 % lead and the formation of secondary

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and tertiary amines severely limited "According to the invention, it is possible to strongly suppress the increasing influence of inactivation effects, which is generally known by reducing the catalyst consumption below 0.5 % ."

Examples example 1

In a 2 1-Ruhrautoklaven different series of experiments to determine specific catalyst consumption depending on defined set hydrogen / ammonia / nitrogen gas mixtures are carried out by each 600 g of tallow fatty acid nitrile with 12 g of a Ni / SiO 2 supported catalyst at 14O C and a total pressure of 50 at After the hydrogenation has ended, the catalyst is separated from the reaction product and used again for further hydrogenations under the same reaction conditions. This procedure is repeated for each series of experiments until the primary amine content obtained is significantly lower than that of the first use of the catalyst. »Derived from the total amount of product reacted, the following specific catalyst consumptions and average product quality are obtained.

Table 1

Composition of the gas mixture on. nitrile

Average, amine quality per test series

hydrogen ammonia nitrogen % prim. secondary " tert " in 1 in 1 in 1 Amin Amine % Amin 75 25 - 0.79 87.9 : 9iV. 2.3 75 25 - 0.25 83.2 14.3 2.5 75 25 3 0.42 92.9 6.8 0.3 75 25 12 0.30 95.4 4.6 - 75 25 20 0.25 98.7 1.3 - 75 25 43 0.56 97.5 2.5 - *

 W * -ϊ Μ

Example 2

To demonstrate the selectivity of the hydrogenation at constant rates in a 2 l Rührautoklalren each 1 kg of a Fettsäurenitrils C ^c ^ g ~ ^C i8 ^ ^and ^ ^{0 e of a supported} nickel / SiO 2 catalyst at 14O C and a total pressure of 50 at one hour hydrogenated in the presence of a defined hydrogen / ammonia / nitrogen mixture »The product qualities obtained are shown in Table 2»

Table 2

Composition of the gas mixture ammonia nitrogen Aminqualxtat secondary. tert " hydrogen in 1 in 1 prim. Amin Amin in 1 25 - Amin 10.5 1.2 75 25 12 88.3 5.5 - 75 25 3 - 94.5 7.5 0.8 75 25 20 91.7 3.2 - 75 25 43 .96,8 1.6 _ 75 98.4

Claims (1)

invention claim Process for the preparation of aliphatic primary amines by
Reaction of fatty acid nitriles containing 5 to 22 carbon atoms, with a 3 to 30 vol .-% ammonia-containing hydrogen to known hydrogenation catalysts and at known pressures and
Temperatures, characterized in that the reaction with
a hydrogen-ammonia gas mixture is carried out to which 5 to 30% by volume, more preferably 12 to 20% by volume, of nitrogen are added.