DD156176A1 - HYDROGENATION METHOD FOR OBTAINING LIQUID FATS - Google Patents

Abstract

The invention relates to a hydrogenation process for obtaining gesaettigter fatty acids from unsaturated fatty acids. The object of the invention is to develop a hydrogenation process which enables the required degree of hydrogenation with little use of catalyst. The task of carrying out the fatty acid dehydrogenation under conditions such that little poisoning of the catalyst used occurs is achieved by carrying out the hydrogenation at 373 K to 483 K and hydrogen pressures of 1 MPa to 3 MPa using Ni-SiO 2 deep-well catalysts becomes. The catalysts are treated after reduction at least at the reduction temperature to complete hydrogen desorption with inert gas and stabilized after cooling to 433 K to 323 K with an inert gas-air mixture before they are used for the hydrogenation. They are used in amounts of 0.05 to 0.35 wt .-% based on the amount of fatty acid used. The hydrogenation time is 1.5 to 2.5 hours.

Description

'' 22743

VEB leuna-V / erke Leuna, 5.12.80

UV / old Ulbricht! I

LP 7895

Title of the invention

Hydrogenation process for the production of fatty acids

Field of application of the invention

The present invention relates to a process for the hydrogenation of unsaturated pesticides

Characteristic of the known technical solutions

It is known that unsaturated fatty acids can be hydrogenated at elevated temperatures under elevated hydrogen peroxide pressure in the presence of hydrogenation catalysts to give the saturated products. Already early processes with relatively active palladium catalysts were developed (GB-PS 18 642). More recent methods work with catalysts in which the palladium on Traeger, such as alumina (DE-OS 2 310 985), ion exchange resins (DE-OS 2 303 170) or MgO, SiO ₂ , TiO, ZrO (DE-OS 2,151,482) , is applied. Although these processes allow continuous hydrogenation with fixed catalyst, they are uneconomical due to the expensive noble metal catalysts.

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For this reason, in the known processes for the hydrogenation of unsaturated fatty acids to saturated fatty acids, nickel-carrier catalysts are usually used which are prepared by precipitation of nickel on kieselguhr (DD-PS 82 906). In these comparatively inexpensive processes, the fatty acids are hydrogenated batchwise with suspended nickel-SiO 2 catalysts in the autoclave, and after the required iodine number has been reached, the catalyst is separated from the hot hydrogenation product by filtration. The consumption of catalyst is relatively high in the known methods, however, because the nickel-kieselguhr catalysts used in these processes, already conditioned by their production process, have greatly fluctuating catalytic activity (compare Surfactants, Journal of Physics, Chemistry and Application of Surfactants , 3 · year, Issue 8, p. 286). In addition, the nickel-kieselguhr catalysts used in the known processes, which are stabilized after reduction with an inert gas-air mixture at temperatures up to 373 K, because of their considerable nickel oxide content, the ratio of Hi to NiO can be up to 1, 5: 10 amount (DE-OS 2,207,909), a relatively low catalytic activity. When stored, these catalysts eventually lose their catalytic activity relatively quickly. Therefore, in the known methods for the hydrogenation of fatty acids must severe reaction conditions such as temperatures up to 533 K, pressures are related to 7 MPa, and catalyst concentrations the reaction mixture to about 0.5% ₉ to the used fatty acid, is maintained to a sufficient degree of hydrogenation to reach. Under the harsh reaction conditions, accelerated poisoning of the catalysts by the fatty acids occurs, so that in the known hydrogenation processes for the production of saturated fatty acids, the catalyst costs represent a significant cost factor.

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Object of the invention

The aim of the invention is to develop a hydrogenation process for the production of saturated petenoic acids, which enables the required degree of hydrogenation with a small amount of catalyst.

Explanation of the essence of the invention

The object of the invention is to carry out the hydrogenation of unsaturated petacids under conditions such that poisoning of the catalyst used is largely avoided.

This object is achieved by carrying out according to the invention the hydrogenation of the unset penta acids to saturated petenoic acids at temperatures of 423 K to 483 K, and hydrogen pressures of 1 I = EPa to 3 × 3 × using a Bi-SiO paell catalyst is produced by co-precipitation of nickel and SiO 2 from nickel salt solution and Hatriumsilikatloesung and after reduction in WaoSerstoffstrom at temperatures of 673 to 723 K then above 673 K as long as with an Inertga3strom from 300 to 1000 v / vh charged until the hydrogen is completely from the Catalyst is desorbed and then after. Abkuehlung to 433 K to 323 K is treated with an inert gas stream, is metered into the air until the exhaust gas 1 to 5 vol .-% oxygen are measured and the air supply is maintained until the temperature has dropped to 323 K, the Katalysaotrmenge in the reaction mixture during the hydrogenation 0.05 to 0.35 wt .-%, based on the amount of pesty used, entrained.

For the process according to the invention, it is usual to use pesticides which contain 10 to 24 carbon atoms per molecule of penta acid and in that the reaction product has an iodine value of less than 2. It is also important that the hydrogenation times are in the range of 1.5 to 2.5 hours. It is beneficial if through the intensively stirred

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Hydrogen reaction mixture is pumped at a rate of 35 to 45 lira / t reaction mixture in the circulation. During the hydrogenation, a thorough mixing of the reaction mixture should be ensured. This mixing is achieved by intensive stirring and by a stream of hydrogen beads through the reaction mixture. The hydrogen stream is pumped in the circulation through the autoclave. Under the conditions of the process according to the invention, a surprisingly good use of the catalyst used can be achieved. The poisoning of the catalyst is much slower than under the conditions of known methods. Surprisingly, the catalysts provided for the process according to the invention show, even after prolonged storage, only a small reduction in their catalytic activity when used under the process conditions according to the invention. Despite lower reaction temperature compared to the known methods, the inventive method provides lower iodine numbers.

Ausfuehrungsbeispiele

Example 1 (comparative example)

A prepared 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, cooled in a hydrogen stream to 353 K and then rinsed at this temperature for 1 hour in inert gas (nitrogen). The catalyst is then stabilized in an inert gas / air mixture containing 1% by volume of oxygen in the inlet until there is no appreciable absorption of acid by the catalyst, ie until the oxygen concentrations in the inlet and outlet of the stabilization container are the same. The load is 500 v / vh in all cases. After grinding the catalyst, it is used in a soaking autoclave for the hydrogenation of tallow fatty acid having an iodine value of 52. Table 1 summarizes the reaction conditions and iodine numbers achieved.

Table 1

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test number 1 2 3 4 Reaction rate (K) 493 453 433 433 V / asserst oil pressure (JJPa) 4 3 3 3 Amount of catalyst on fatty acid {%) 0.4 0.2 0.2 0.2 Hydrogenation time (h) 3 0.5 0.5 0.5

Achieved residual iodine number 1.8 29.8 37.0 49.1

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 (comparative example)

A by common Paollung of nickel and SiO from nickel catalyst containing 50 % nickel is reduced for 8 hours at 723 K in a stream of hydrogen, cooled in hydrogen to 353 K and then rinsed at this temperature for one hour in inert gas (nitrogen). Thereafter, the catalyst with an inert gas-air mixture containing 1 vol .-. 5 Sodium in the entrance, stabilized until no significant Säurerst offaufnähme more, d, h, until the oxygen concentrations in the inlet and outlet of the Stabilisierungsbehaelters are equal , The load is 500 v / vh in all paellen. After grinding the catalyst, it is used in a soaking autoclave for the hydrogenation of tallow fatty acid having an iodine value of 52. Table 2 summarizes the reaction conditions and the iodine numbers achieved.

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Table 2

test number 5 6 7 8th Reaction Temp. (K) 493 453 433 433 Hydrogen pressure (MPa) 3 3 3 3 Amount of catalyst fatty acid (%) 0.4 0.2 0.2 0.2 Hydrogenation time (h) 3 0.5 0.5 0.5 Achieved residual iodine number 1.5 19.2 24.3 36.1

In experiments 5 to 7 freshly reduced and stabilized catalyst was used. In experiment 8, a catalyst was used which had been stored in air for half a year.

Example 3

A combination of nickel and SiO _? Nickel catalyst prepared from nickel salt solution and sodium silicate solution with a nickel content of 50 % is reduced in a stream of hydrogen at 723 K for 8 hours, purged with nitrogen at 723 K for 1 hour, and then cooled to 353 K in this inert gas stream. At this temperature, the catalyst is stabilized with an inert gas-air mixture containing 1% by volume of oxygen in the inlet until no appreciable uptake of acid by the catalyst occurs, ie until the acid concentrations in the inlet and outlet of the stabilization tank are equal. The load is 500 v / vh in all paellen. After grinding the catalyst, it is used in a soaking autoclave for the hydrogenation of tallow fatty acid having an iodine value of 52. "Table 3 summarizes the reaction conditions and the iodine numbers achieved.

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Table 3

9 10 11 12 483 453 433 433 3 3 3 3 0.35 0.2 0.2 0.2 2 0.5 0.5 0.5

Verouchsnummer

Reaktionstenp. (K)

Water pressure off (HSPa)

Amount of catalyst

fatty acid (%)

Hydrogenation (h) _ _, "_, ^ _, _,

Achieved residual iodine number 1.2 9.4 13.0 16.5

In experiments 9 to 11, freshly reduced and stabilized catalyst was used. In Experiment 12, a catalyst was used which had been stored in air for half a year c

A comparison of the results of Comparative Examples 1 and 2 with the experiments carried out under conditions according to the invention from Example 3 makes it clear that the erfindungsgeinaesse method allows significantly lower residual iodine numbers.

Claims (2)

-3- 22 74 3 5 6 Invention claim A hydrogenation process for obtaining saturated fatty acids in the presence of suspended nickel-SiC ^ catalysts, characterized in that the hydrogenation is carried out at temperatures of 423 K to 483 K and hydrogen pressures of 1 MPa to 3 MPa and using a nickel-SiO 2 precipitating catalyst which has been prepared by coprecipitation of nickel and SiC ^, followed by reduction in Hp flow and subsequent treatment with an inert gas stream above a temperature of 673 K until the hydrogen is completely desorbed from the catalyst and stabilized with oxygen-containing inert gas the amount of catalyst in the reaction mixture during the hydrogenation is 0.05 to 0.35% by weight, based on the amount of fatty acid used, » 2. The method according to item 1, characterized in that unsaturated fatty acids having 10 to 24 carbon atoms per molecule are used · 3 »process according to item 1 to 2, characterized in that the hydrogenation time is 1.5 hours to 2.5 hours. 4. The method according to item 1 to 3, characterized in that hydrogen is pumped through the intensively stirred reaction mixture at a rate of 35 b: mixture in the circulation. 2 at a rate of 35 to 45 ITm / t reaction