DD156177A1 - METHOD FOR HYDROGENATION OF FATSAEURENITRILES - Google Patents

Abstract

The invention relates to an improved process for the hydrogenation of fatty acid nitriles having 6 to 24 carbon atoms in the molecule, in which the required degree of hydrogenation is achieved with lower catalyst usage and better selectivity. The task of carrying out the fatty acid nitrile hydrogenation under such conditions that it is possible to make extensive use of the catalyst used is achieved by hydrogenating at 393 K to 473 K, hydrogen pressures of 2 MPa to 5 MPa, NH 3 pressures of 0.5 MPa and hydrogenation times of 2 to 2.5 hours using a nickel-silica catalyst in amounts of 0.45 to 0.4% (based on the amount of fatty acid nitrile used) is performed. The catalyst employed has a particle size distribution of more than 90% by weight with particle sizes of less than 32 μm and not more than 10% by weight with particle sizes of less than 1 μm and is formed by joint leaching of carrier and nickel at a carbonate ion concentration of at least 55 in the case suspension g / I produced. 30 to 300 ml of a 40% sodium hydroxide solution / kg of catalyst are added to the reaction mixture before the fatty acid nitriles are hydrogenated.

Description

a) Title of the conclusion

Process for the hydrogenation of fatty acids!

b) Field of application of the invention

The present invention relates to an improved process cure hydrogenation of fatty acid tri-yetene having 6 to 24 carbon atoms in the molecule to primary fatty amines

c) Characteristics of the known technical solutions For the hydrogenation of fatty acids to primary Fe

Amines are usually used in processes in which the powdered catalysis is suspended in citrile, Different catalysts are used «In processes that work with Kicke-copper-manganese catalysts (DD-PS 55 959), the catalyst cokes are indeed relatively low However, unsatisfactory degrees of conversion and low yields of primary amines are obtained. Substantially better conversion rates are achieved in processes; use the Raney Niekel as a catalyst (DE-AS 1 543 762, US Patent 2 287 219). A disadvantage of Raney-Kickel is that the catalyst can not be stabilized against the oxygen attack of the air and therefore causes considerable difficulties in handling. The costly production process and the high cost of ownership are the reasons for the cost

Use of Raney nickel significantly higher than when using Nicke1 supported catalysts. Very selective work methods in which Raney ~ cobalt is used (GB-PS 1 388 053) "These catalysts are even more 'expensive' than Raney nickel. Also, in processes employing cobalt precipitated catalysts with basic additives, the catalyst costs are considerable, since these catalysts are relatively inert and have reaction temperatures up to above; 473 K need (DE-AS 1 518 118), This also applies to the known ancestor with nickel-supported catalysts. Although the catalysts are cheaper, but also high reaction temperatures must be maintained. In addition, catalyst concentrations in the reaction mixture of more than 0.5 %, based on the amount of fatty acid used and reaction times of up to more than 2.5 hours, are necessary to sufficiently hydrogenate the nitriles. However, under these reaction conditions, the formation of secondary and tertiary hydrocarbons is increased promoted tertiary amines. The lack of catalytically ^ activity of the precipitated catalysts used in the known processes becomes part caused by the very poorly reproducible preparation process of the catalysts (see "surfactants, Journal of Physics, Chemistry and application of _surfactants? 3.Jahrgang No. 8, p 286) , Another reason for the high catalyst consumption lies in the unfavorable grain spectrum of the used nickel-KieseIgur catalysts. The relatively high proportion of very finely divided catalyst grains leads to difficulties in the separation of the catalyst after hydrogenation. On the other hand, the high proportion of coarse catalyst particles causes insufficient utilization of the inner catalyst surface due to diffusion inhibitions in the pore system of the catalyst grains. -..- «-.- ..

2 7 4 4

d) Object of the invention

The object of the invention is to develop a process for the hydrogenation of fatty acid nitriles having 6 to 24 C atoms in the molecule to give pottamines, which with low catalyst use allows the required degree of hydrogenation with better selectivity.

Explanation of the essence of the invention

The invention is based on the object, the hydrogenation of fatty acids! Trilen carried out under such conditions that a ,, extensive use of the catalyst used and at the same improve the selectivity is achieved _e

This task is solved ge _; according to the invention, the hydrogenation of the fatty acid nitriles at temperatures of 393 K. to 473 Kj hydrogen pressures of 2 MPa to 5 MPa, NH ₅ partial pressures of O ₃ 5 MPa to 2 MPa and hydrogenation times of 2 to 2j5 hours using a nickel / SiIizium ~ Pällkatalysators dioxide is carried out in amounts from 0.45 to 0.4 ^(fo (based on the amount Fettsäurenitrilmenge). the catalyst "is prepared by co-precipitation of carrier and nickel or" by the addition of nickel solution to a mixture solution of sodium carbonate ™ and Sodium silicate solution in a period of at least 2 hours at a concentration of carbonate ions in the precipitation suspension of at least 00 g / l and at a temperature of 330 K to 340 K ₅ filtration, washing, stabilization with oxygen-containing inert gas and grinding is prepared, wherein for the catalyst used in the hydrogenation has a particle size distribution of more than 90% by weight with particle sizes before »small al s 32 / and and

at most 10 wt fo with grain sizes smaller than 1 / nn and a nickel ™ silica ratio of 3 to 5. having 1. It is important to accelerate the dissolution of the hydrogen in the reaction product by vigorous stirring or stirring while passing a hydrogen stream of 10 to 50 Nm / kg, which is recirculated. In addition, the addition of 30 to 300 ml of a 4-oven NaOH solution / kg of catalyst to the reaction mixture before the start of the hydrogenation advantageous. Under the conditions of the process according to the invention a good use of the catalyst used is given. In addition, these relatively mild conditions improve the selectivity of the reaction so that in addition to low catalyst consumption and good yields of primary amines are achieved.

embodiments

Example 1 (Comparative Example)

A nickel-KieseIgur catalyst was prepared in a known manner according to the following recipe:

200 g of diatomaceous earth were suspended in 15 l of water in a solution of 5 kg of crystallized nickel nitrate. The suspension was heated to 335 K and a solution of 2.7 kg of sodium carbonate in 15 1 of water added within 1 hour. The precipitate formed was filtered off, washed with water and 10 hours at. 395 K dried »Then the filter cake was deformed and heated in the air stream for 2 hours at 675 K. After activation in the hydrogen flow stream at 725 K, the catalyst was stabilized in a stream of nitrogen with an oxygen content of 0.5 vol. In the subsequent comminution with a mill speed of 5000 rev / min was the following

*% <s% py β

Grain distribution obtained: 24 C-ew _a % of the catalyst had a particle size below l ^ tni and 31 Gew # of the catalyst> a grain size over 32, on.

This catalyst was used in a stirred autoclave for the hydrogenation of fatty acid nitrile, which was 50 ml of a 40 $>i'gen NaOH solution / kg catalyst eye eyes set. Table 1 summarizes the reaction conditions and the degrees of conversion achieved to amines.

Table 1

393 3 3 * 7 I ₅ 41 O, 2 30 , 0 24

Reaction temperature. (K) 423 423

Hydrogen pressure (MPa) 3.3 3 ^ 3

ΝΗ, pressure (MPa) 1.7 1.7

.Catalyst Amount (<&) 0.46 0.41

Hydrogenation time (h) 2.75 2

Umsata too. Amines (β) 99.2 95

Sales to primary era in (ß) 74.4 72.2

Example 2 (Inventive Example)

A nickel yellow precipitate catalyst was prepared according to the following recipe;

2 g of 7 kg of sodium carbonate were slurried in 8 l of water and warmed to 335 ° K. Within 30 minutes, 4.45 l of a solution of sodium silicate containing 45 g of silicon dioxide / l were added with vigorous stirring *. Subsequently, 5 kg of crystalline nickel nitrate were dissolved in enough water to give 7 liters of solution. "This solution was added at a rate of 3.5 l / h. Uniformly with vigorous stirring to the sodium silicate / sodium carbonate solution kept at 335 K." The resulting precipitate was filtered off, washed with water

⁶ -22 7 4 4 3 6

Dried for 10 h at 425 K, reduced in hydrogen flow at 725 K, stabilized in a nitrogen stream with an oxygen content of 0.5 Vol.ii and then comminuted at a mill speed of 5000 rev / min. The catalyst had the following distribution *. The catalyst had a particle size below IAm and 0% by weight of the catalyst was greater than 32 μm. This catalyst was used in a stirred autoclave to hydrogenate fatty acids containing 50 ml of a 4X NaOH solution. kg of catalyst were used. Table 2 summarizes the reaction conditions and the degrees of conversion achieved to amine

Table 2

Experiment number '4 5

Reaction temperature (K) 423 393 Hydrogen pressure (MPa) 3.3 3.3 NH 2 pressure (MPa) 1.7 1.7 Amount of catalyst (%) 0.41 0.41 Hydrogenation time (h) 2 2 Sales to Amines (#>) 99.3 76 Sales to primary amine (#) 83.4 65.4

Example 2 makes it clear that higher conversions are achieved under the conditions according to the invention.

Claims (2)

Erfindungcanspruch le method for hydrogenating τοπ fatty acid nitriles having 6 to 24 carbon atoms in the molecule in egg sump phase with suspended Niokel-Siliziumdioxia Katalysatorj characterized in that the hydrogenation of the fatty acid nitriles at temperatures Clay 393 E to 473 K, hydrogen pressures of 2 MPa to 5 MPa ₃ KH ^ partial pressures of Oj5 MPa to 2 MPa and hydrogenation times of 2 to "2 j 5 hours using a nickel · - silica precipitated catalyst in amounts of 0 _s 45 to 0 _? 4 # (based on the amount of fatty acid used) by simultaneously precipitating support and nickel, respectively, by adding nickel solution to a mixed solution, sodium carbonate and sodium silicate solution for a period of at least 2 hours at a carbonate ion concentration in the precipitation suspension of at least 55 g / l and at one temperature From 330 If to 340 Kj Filter, Wash, Dry, Reduce ^ Stabilize with inert oxygen-containing gas and grind where the catalyst used for the hydrogenation has a particle size distribution of more than 90% by weight with particle sizes of less than 32.Ii-rn and at most 10 G-ew / jS with particle sizes smaller than 1 / via and a niocelium-silica Yerverhältnis of 3 to 5 ι 1 on v / ei st » 2. s method according to point 1. ₅ characterized _? that the reaction mixture is stirred intensively or in addition to stirring • κ simultaneously a hydrogen flow of 10 to 50 Nm / h is circulated through the reaction mixture «.