DD156178B1 - HYDROGEN PROCESS FOR THE PREPARATION OF PRIMARY FETTAMINES - Google Patents

Description

-2- 274 42

The effect of the particular inert gas treatment of the catalyst at 673 to 723 K and 300 to 1000 V / Vh until complete removal of the hydrogen is an improvement in catalytic activity both compared to other stabilization processes and compared to the original, reduced but unstabilized catalyst. This improvement represents a substantial improvement in the catalyst and is not only a reduction in the loss of stabilizing activity as compared to the freshly reduced, yet unstabilized catalyst. It is advantageous for the process according to the invention that 30 to 300 ml of a 40% strength NaOH solution / kg of catalyst are metered into a fatty acid-nitrile catalyst mixture in the autoclave before the beginning of the hydrogenation. It is important to accelerate the dissolution of the hydrogen in the reaction product by vigorously stirring the stirring while passing a hydrogen stream of 10 to 50 Nm ³ / ht, which is recycled. For the process according to the invention, fatty acid nitriles having 6 to 24 carbon atoms per molecule are used.

Under the conditions of the process according to the invention a good use of the catalyst used. In addition, the reaction proceeds under these relatively mild conditions with relatively high selectivity, so that in addition to low catalyst consumption and good yields of primary amines are possible.

Exemplary embodiments

Example 1 (comparative example)

A nickel catalyst prepared by coprecipitation of nickel and S1O2 from nickel salt and sodium silicate solution containing 50% nickel is reduced in hydrogen flow at 723K for 8 hours, cooled to 353K in hydrogen stream and then purged at that temperature for one hour in an inert gas stream (nitrogen) , Thereafter, the catalyst is stabilized with an inert gas-air mixture containing 1% by volume of oxygen in the inlet until there is no appreciable oxygen uptake, d. H. the oxygen concentrations in the inlet and outlet of the stabilization tank are the same. The load is in all cases 500V / Vh. After grinding the catalyst, it is used in a stirred autoclave for the hydrogenation of fatty acid nitrile to which 40 ml of a 40% strength NaOH solution / kg of catalyst have been added. Table 1 summarizes the reaction conditions and the degrees of conversion achieved to amines.

Table 1

test number (K) 1 2 3 4 reaction temperature (MPa) 423 423 393 393 Hydrogen pressure (MPa) 3.3 3.3 3.3 3.3 NH ₃ -DmCk (%) 1.7 1.7 1.7 1.7 amount of catalyst (H) 0.41 0.36 0.36 0.36 hydrogenation (%) 2 1.6 1.6 1.6 Sales to amines 99.0 96.2 59.4 32.8 Sales to primary (%) amines 82.2 80.2 50.5 28.9

In experiments 1 to 3 freshly reduced and stabilized catalyst was used. In Experiment 4, a catalyst was used which had been stored in air for half a year.

Example 2 (Inventive Example)

A nickel catalyst prepared by co-precipitation of nickel and silica from nickel salt and sodium silicate solution containing 50% nickel is reduced in hydrogen flow at 723K for 8 hours, purged with nitrogen at 723K for 1 hour and then cooled to 353K in this inert gas stream. At this temperature, the catalyst is stabilized with an inert gas-air mixture containing 1 vol.% Oxygen in the inlet until there is no appreciable oxygen uptake by the catalyst, i. the oxygen concentrations in the inlet and outlet of the stabilization tank are the same. The load is in all cases 500V / Vh. After grinding the catalyst, it is used in a stirred autoclave for the hydrogenation of fatty acid nitrile to which 40 ml of a 40% strength NaOH solution / kg of catalyst are added. Table 2 summarizes the reaction conditions and the degrees of conversion achieved to amines.

Table 2

test number

reaction temperature (K) Hydrogen pressure (MPa) NH ₃ -DmCk (MPa) Kata lysato rm e η g e (%) hydrogenation (H) Sales to amines (%) Sales to primary amines (%)

423 3.3 1.7 0.36

393 3.3 1.7 0.36 1.6 92.2

80.2

393 3.3 1.7 0.36 1.6 91.0

79.2

In experiments 5 and 6, freshly reduced and stabilized catalyst was used. The catalyst used in Run 7 had been stored in air for half a year before use.

Example 2 shows that under the conditions of the process according to the invention with low catalyst use higher conversions to amines are achieved. Even after prolonged storage of the catalyst provided for the process according to the invention, comparatively good hydrogenation results are achieved.

-3- 274 42

Example 3

4 batches of a catalyst prepared according to Example 2 were then treated after reduction at different temperatures for 1 hour with a nitrogen flow of 800V / Vh and then stabilized as described in Example 2 and used for Nitrilhydrierung.

The inert gas treatment temperature, the reaction conditions and the degrees of conversion to amines achieved are summarized in Table 3.

Table 3

Test number 8 9 10 11

Inertgasbehandlungstem- (K) 643 673 723 753 temperature of the catalyst (K) 423 423 423 423 reaction temperature (MPa) 3.3 3.3 3.3 3.3 Hydrogen pressure (MPa) 1.7 1.7 1.7 1.7 NH ₃ -DmCk (%) 0.36 0.36 0.36 0.36 amount of catalyst (H) 1.6 1.6 1.6 1.6 hydrogenation (%) 97.1 99.3 99.5 98.0 Sales to amines Sales to primary (%) 79.6 87.1 85.9 81.2 amines

The comparison of Experiments 8 to 11 (Example 3), 5 (Example 2) and 2 (Example 1) shows that the nitrile hydrogenation when using the invention treated catalysts (Experiments 5,9 and 10) significantly better hydrogenation (conversion to amines and Primäraminausbeute) than in the experiments 2, 8 and 11 results.

Experiment 2: uncontrolled cooling in a stream of nitrogen

Experiment 8: Insufficient H ₂ desorption due to treatment temperature that is too low. Experiment 11: Thermal damage to the catalyst due to excessively high treatment temperature.

Example 4

4 batches of a catalyst prepared according to Example 2 were then treated after reduction at 723 K for 1 hour with nitrogen of different load and then stabilized as described in Example 2 and used for nitrile hydrogenation. The nitrogen load in the catalyst treatment, the reaction conditions and the degrees of conversion achieved to amines are summarized in Table 4.

Table 4

Test number 12 13 14 15

Nitrogen pollution of the (K) 200 300 1000 1500 Catalyst (V / Vh) (MPa) 423 423 423 423 reaction temperature (MPa) 3.3 3.3 3.3 3.3 Hydrogen pressure (%) 1.7 1.7 1.7 1.7 NH ₃ pressure (H) 0.36 0.36 0.36 0.36 amount of catalyst (%) 1.6 1.6 1.6 1.6 hydrogenation 97.7 99.2 99.6 98.3 Sales to amines (%) Sales to primary • 81.3 89.1 88.3 79.4 amines

The comparison of Experiments 12 to 15 shows that only the catalysts used in the invention in Examples 13 and 14 give sufficient activity and selectivity in the nitrile hydrogenation.

The reason for the low activity and selectivity in the hydrogenation in Experiment 12 is the insufficient removal of the chemically bound hydrogen before the air stabilization of the catalyst used. An explanation for the performance degradation when using catalysts that have undergone an overdosed nitrogen treatment (Experiment 15) can not be given.

Example 5

A catalyst prepared according to Example 2 was used in various amounts in a stirred autoclave for the hydrogenation of fatty acid nitrile to which 40 ml of a 40% strength NaOH solution / kg of catalyst were added. Table 5 summarizes the reaction conditions and the degrees of conversion achieved with amines.

Table 5

test number

16

18

Reaction temperature (K)

Hydrogen pressure (MPa)

NH ₃ pressure (MPa)

Amount of catalyst (%)

Hydrogenation time (h)

Sales to Amines (%) Sales to Primary

Amines (%)

423 3.3 1.7 0.33 1.6 98.2

423 3.3 1.7 0.40 1.6 99.7

88.3

423 3.3

1.7 0.42 1.6 99.8

80.6

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Comparison of Experiments 16, 17 and 18 (Example 5) and 5 (Example 2) shows that with insufficient amounts of catalyst, both amine and primary amine formation do not meet the target> 99.0% and> 85%, respectively. Overdose of Jes catalyst (Experiment 18) probably leads to a high nitrile conversion, but at the same time the deamination of the drimeric amine to secondary and tertiary amines increases unacceptably. The consequence is the designated low primary amine content in the hydrogenation product.

Example 6

A nickel catalyst prepared by co-precipitation of nickel and SiO ₂ from nickel salt solution and sodium silicate solution containing 50% nickel is reduced for 8 hours at 723 K in a hydrogen stream and then cooled and passivated in an inert gas stream according to US Pat. No. 2,677,668. The catalyst is ground and used in a stirred autoclave for the hydrogenation of fatty acid nitrile to which 40 ml of a 40% strength NaOH solution / kg of catalyst have been added. Table 6 summarizes the reaction conditions and the degrees of conversion achieved to amines.

Table 6

test number

19

21

Reaction temperature (K)

Hydrogen pressure (MPa)

NH ₃ pressure (MPa)

Amount of catalyst (%)

Hydrogenation time (h)

Sales to Amines (%) Sales to Primary

Amines (%)

423 3.3 1.7 0.36 1.6 94.3

423 3.3 1.7 0.40 1.6 96.8

80.5

423 3.3 1.7 0.45 1.6 97.5

79.6

The comparison of the experiments 19,20 and 21 shows that despite increased amount of catalyst (experiment 21), both the conversion to amines and the Primäraminbildung not the target position> 99% or. > 85% match. In overdose of the catalyst occurs beyond the deamination to form secondary and tertiary amines, The result is reached the lower primary amine content in the hydrogenation product.

Example 7

A prepared according to DD-PS 152686 catalyst is used in a stirred autoclave for the hydrogenation of fatty acid nitrile, 40 ml of a 40% NaOH solution / kg catalyst were added. Table 7 summarizes the reaction conditions and the degrees of conversion achieved to amines.

Table 7

test number

22

24

Reaction temperature (K)

Hydrogen pressure (MPa)

NH ₃ pressure (MPa)

Amount of catalyst (%)

Hydrogenation time (h)

Sales to Amines (%) Sales to Primary

Amines (%)

423 3.3 1.7 0.36 1.6 91.8

423 3.3 1.7 0.40 1.6 92.3

81.4

423 3.3 1.7 0.45 1.6 98.1

78.3

The results of experiments 22, 23 and 24 show that with the o.g. Catalyst the target position> 99% amine yield and> 85% Primäraminausbeute were not reached. If the amount of catalyst exceeds 0.5%, amine formations> 99% are possible, but primary amine formation is only 75%.

Example 8

A produced by precipitation of nickel on diatomaceous earth nickel catalyst with a nickel content of 50% is reduced for 8 hours at 723 K in a stream of hydrogen and then cooled and passivated according to US-PS 3868332 in inert gas. The catalyst is ground and used in a stirred autoclave for the hydrogenation of fatty acid nitrile to which 40 ml of a 40% strength NaOH solution / kg of catalyst have been added. Table 8 summarizes the reaction conditions and the degrees of conversion achieved to give amines.

Act 8

test number

25

27

Reaction temperature hydrogen pressure NH ₃ pressure catalyst amount hydrogenation time conversion to amines Revenue to primary amines

(K)

(MPa)

(MPa)

423

81.1

423 3.3 1.7 0.45 1.6 90.7

78.1

423 3.3 1.7 0.50 1.6 93.8

78.2

The results show that much higher amounts of catalyst than in the examples according to the invention (eg Experiment 5) still give unsatisfactory conversions to amines and low yields of primary amine.

Claims (1)

-1- 274 42 Invention claim: Process for the preparation of primary FettsJ having 6 to 24 C-atoms per molecule, by hydrogenation at temperatures above 393 K of suspended Ni / SiCVKataiysator by co-precipitation of nickel and SiC ^ from nickel salt and sodium silicate solution followed by reduction in a hydrogen stream at temperatures of 673 to 723 K, rinsing in an inert gas stream and conventional air stabilization with oxygen at temperatures of 433 to 323 K, characterized in that the hydrogenation is carried out using 0.35 to 0.40% of catalyst, which after its reduction is treated at a temperature of 673 to 723 K with an inert gas of 300 to 1 000V / Vh until the hydrogen is completely desorbed from the catalyst is carried out. Field of application of the invention The present invention relates to a process for the hydrogenation of fatty acid nitriles to primary fatty amines. Characteristic of the known technical solutions For the hydrogenation of fatty acid nitriles to primary fatty amines, processes are usually used in which the powdery catalyst is suspended in nitrile. Different catalysts are used. In processes using nickel-copper-manganese catalysts (DD-PS 55959), although the catalyst costs are relatively low, unsatisfactory levels of conversion and low yields of primary amines are obtained. Significantly better degrees of conversion are achieved in processes that use Raney nickel as a catalyst (DE-AS 1 543762, US-PS 2287219). A disadvantage of Raney nickel is that the catalyst can not be stabilized against the oxygen attack of the air and therefore causes considerable difficulties in handling. The costly manufacturing process and the high nickel content, the cost of using Raney nickel are significantly higher than when using nickel-supported catalysts. Very selective work methods in which Raney-Kobait is used (GB-PS 1 388053). These catalysts are even more expensive than Raney nickel. Even in the case of processes which use cobalt precipitation catalysts with basic additives, the catalyst costs are considerable, since these catalysts are comparatively inactive and require reaction temperatures of more than 473 K (DE-AS 1518118). This also applies to the known processes 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 to more than 0.5%, based on the amount of fatty acid nitrile used and reaction times of up to more than 2.5 hours are necessary to hydrogenate the nitriles sufficiently. However, under these reaction conditions, the formation of secondary and tertiary amines is promoted. The lacking catalytic activity of the precipitation catalysts used in the known processes is caused in part by the poorly reproducible production processes of the catalysts (compare Surfactants, Journal of Physics, Chemistry and Application of Surfactants, Volume 3, Issue 8, p. , Usually, in the preparation of the catalysts is carried out so that after reduction at temperatures greater than 423 K, the reduction apparatus is purged with inert gas and cooled simultaneously to room temperature, before by adding oxygen to the inert gas at temperatures up to max. 323 K is stabilized (US-PS 2677668, US-PS 3868332, DE-PS 1144236). Purging with inert gas displaces the hydrogen from the gas space of the catalyst bed. In this case, the catalyst bed cools relatively quickly because the recirculated inert gas stream is cooled to about 278 to 283 K for vapor deposition. These conditions are not sufficient, in particular, to remove this considerable amount of chemically bound hydrogen from the catalyst. So treated with inert gas catalyst still results in local overheating in the catalyst bed in the subsequent stabilization with oxygen. It is believed in US Pat. No. 2,677,668 that these localized superheats are caused by oxidation of hydrogen at the surface of the catalyst during stabilization. Due to these local overheating, stabilization leads to increased oxidation, in particular of the catalytically active catalyst surface, which is why these catalysts have a comparatively low catalytic activity. Finally, when stored, the catalysts continue to lose catalytic activity relatively rapidly, so that the known hydrogenation processes for obtaining primary fatty amines have a high catalyst consumption. The catalyst costs are therefore a significant cost factor in these processes. Object of the invention The aim of the invention is to develop a process for the hydrogenation of fatty acid nitriles to fatty amines, which allows complete conversion of the nitriles and a high yield of primary fatty amines with less catalyst requirement. Explanation of the essence of the invention The invention has for its object to investigate the hydrogenation of fatty acid nitriles perform conditions that a high utilization of the catalyst used and a high selectivity of the hydrogenation is achieved. This object is achieved according to the invention by hydrogenating the fatty acid nitriles at temperatures of 393 to 473 K, hydrogen pressures of 2 MPa to 5 MPa, NH ₃ pressures of 0.5 MPa to 2 MPa and hydrogenation times of 1.5 to 2 hours using a nickel S ^ precipitated catalyst in amounts of 0.35 to 0.4% (reduced to the amount of fatty acid nitrile) is carried out. The catalyst is prepared by coprecipitation of nickel and silicon dioxide from a nickel salt and sodium silicate solution, reduction in hydrogen flow at temperatures of 673 to 723K and subsequent loading with an inert gas flow of 300 to 1000 V / Vh at temperatures above 673 K until the Hydrogen is completely desorbed from the catalyst. The difference from the customary inert gas purging of the catalysts after reduction is that, according to the invention, purging is carried out with a defined inert gas stream at a temperature above 673K. Only after complete removal of the interstitial sites of the nickel and partly present as nickel hydride chemically bound hydrogen is cooled in the usual inert gas stream. After cooling to 433 to 333 K, the catalyst thus prepared is treated with an inert gas stream, into which air is metered, until 1 to 5% by volume of oxygen are measured in the offgas. The air supply is maintained until the temperature has dropped to 323K.