DE2051320B2 - Process for the purification of aliphatic dicarboxylic acid mixtures - Google Patents

Description

is-

3 4

Acidifiers in the textile and leather industry In this way, 95 percent by weight of the

use. But you can also recover the mixture in the copper and vanadins,

Separate pure acids. The crucial importance of using one

_. . Thin film evaporator when performing the

Example 1 ₅ procedure results from the following comparison

350 kg of a raw dicarboxylic acid scfamelze, which can be exemplified:

after distilling off nitric acid and water from.,. . ,. ■ ·. ,
an oxidation mixture obtained and the to 31 Ge comparison examples
weight percent from adipic acid, 20 weight percent In the same Sambay vat as in Example 1, from succinic acid and 47 weight percent from GIuio with an evaporator area of 2.4 m *, there are tarsic acid and another 0.36 weight percent K up-195 ° C 335 kg / h of succinic acid and 0.11 percent by weight of vanadium are also co-distilled under vacuum. The distillate contains 217 kg of succinic acid gen amounts of impurities are per and 100 kg of succinic anhydride. In addition, 18 kg of water are condensed out in a freezer in a Sambay evaporator for an hour, an area of 2.4 m ^{2 is} supplied via a pump. 15 During the destination, 32.5% of the Bern-At a temperature of 182 ° C and a pressure of stinic acid are converted into succinic anhydride.
10 Torr distill 335 kg of the dicarboxylic acid mixture _v ... u. -: -! _7th
per hour over, with the composition as vergiejcnsoeispiei ζ
as follows: 31 percent by weight of adipic acid, 21 percent by weight of succinic acid and 48 percent by weight of 25 g of molten dicarboxylic acid are placed in a round bottom flask with a Claisen attachment. With a percentage of glutaric acid. This corresponds to a yield of continuous feed of 250 g dicarboxylic acid mixture / h of 95.5% of pure dicarboxylic acids, based on the oil bath heating at a temperature of the oxidation mixture before separation of nitric acid 184 ⁰ C in vacuum continuously 237 g of distillate over and water. A residue is obtained which has been removed at the top and continuously contains 13 g / h of total amounts of the catalyst substance at the bottom and 5 product is withdrawn. The distillation is 4 hours which is very fluid. operated continuously. During this time the

The initial level is held in the flask so that the ^Bei P ^{2 iel-average} residence time of 6 mm. Using

370 kg of a crude dicarboxylic acid melt, best of a dicarboxylic acid mixture as in Example 1, was obtained

starting from 29 weight percent adipic acid, 49 parts a distillate of the following composition:

weight percent glutaric acid and 20 weight percent η ♦ · - 4 8 ° /

Succinic acid and also 0.41 percent by weight amber-mycic acid. ^^ _. / <, Copper and 0.12 percent by weight vanadium in addition to natural amber

wrestling amounts of impurities, are pro - ,. "" - "ÜL'wi, -; ^ \ VV

Hour a Sambay vaporizer via a pump 35 glutaric anhydride 1.2 / _o

fed. At a temperature of 184 ° C and an adipic acid, 0

Pressure of 5 torr distill 355 kg of the dicarbon from the examples and the comparative examples

acid mixture over, which corresponds to a yield of it can be seen that only the distillation of the crude dicar-

96.1 percent by weight of pure dicarboxylic acids. acid mixture in a thin film evaporator

The Sambay residue, which leads to 10.1% copper and 40 to a distillate that is made from the unchanged

2.9% vanadium consists of traces of iron and cobalt dicarboxylic acids. Distillation of individual grain

contains, is in a combustion chamber with natural gas components (succinic acid) or minor changes

burned at 1200 ^{0 C.} The flue gases on the distillation system lead to distillates,

200 ⁰ C cooled and then pass a no longer from the mixtures of pure Dicarbon-

Electrostatic precipitator on which the oxides are deposited. 45 acids consist.

Claims (1)

in this case, as a result of excessive dwell times, very large patent claim: residues are formed. It has now been found that a pure ash- Process for the purification of aliphatic free and anhydride-free mixtures of adipic acid, dicarboxylic acid counterparts containing adipic acid, glutaric acid and succinic acid, containing as acid and succinic acid and only small amounts of these compounds due to residue, oxidation of cyclohexanol / cydohexanone gene ^r the entire catalyst fractions remain when the crude kaialysatorhalog dicarboxylic acid hexane is mixed with nitric acid at an elevated temperature after the nitric acid has been distilled off and in the presence of copper and vanadium 10 of the water in the presence of copper and vanadium 10 of the water, at a temperature of 170 Catalysts up to 240 ⁰ C are obtained, thereby and at a pressure of 1 to 20 Torr over a characteristic t "that mim leads the mixtures to the thin-film evaporator,
dran AbdöätflÖefen of nitric acid and water after the proper procedure Purified at a temperature of 170 to 240 ⁰ C and an oxidation mixture, which one at the loading pressure of 1 to 20 Torr over a thin layer 15 treatment of cyclohexanol and cyclohexanone with evaporator leads to high-percentage nitric acid, z. B. a saltpeter acid of about 55 to 58%, at 75 to 8O ⁰ C in the presence of copper and vanadium catalysts obtained. In a conventional two-stage distillation ao nitric acid and water separated. Possibly After removing nitric acid and water, a sump treatment at 180 C can also be used to destroy it of the nitro compounds in the residue Go in the manufacture of adipic acid from one. This distillation residue then contains Mixture of cyclohexanol and cyclohexanone through »5, in addition to adipic acid, glutaric acid and amber oxidation with nitric acid in the presence of vanic acid, the total amount of copper and vanadindium and copper-containing catalysts, the catalyst is partly obtained in the form of the oxides. Besides Mixtures in which, in addition to adipic acid, larger quantities are found in the mixture, small quantities of genes contain glutaric acid and succinic acid. Impurities. The aim is to reduce the amount of glutar and amber. B. to keep stinic acid as low as possible. A known method in a Sambay vaporizer is advantageous in that one runs a certain temperature of 180 to 200C. At a pressure of 1 to 20 Torr from the circulation of the oxidation product, it is possible to subtract 94 bis in order to ensure that the level of by-products 96 percent by weight of the feed remains low in a gentle manner. To be distilled over when working up this 35 and with very short dwell times. In contrast to the known processes, the acid and water are distilled off to 4 and less percent by weight through a two-stage distillation. If necessary, it is used for the destruction of lowers. Another advantage of the process is that nitro compounds in the residue from the bottom are ^{kept at a temperature of 180 °} C. for 2 hours from the evaporation residue. 40 can fully recover catalyst. A dark-colored melt remains behind; B. and vanadium catalysts in addition to some impurities by leaching the residue with water. Catalyst in F "- *. * On salts up to 40% in again The separation of the mixture of pure acids 45 usable t orm back. But you can also burn the residue from this distillation residue with natural gas in order to avoid it, with copper and further losses taking place in a gentle manner. Vanadium in the form of oxides from the flue gases From the French patent specification 15 55 151 it is never known, for example, by means of an electrostatic precipitator or a cloth filter, that this can be whipped up by a water drain. Here too, steam distillation is achieved. The process is technically 5 ° but very expensive to use the catalyst in an amount of 70 to 90%. The other option is back. The precipitate, after dissolving in Sal is in a column distillation at a temperature peter acid door again used directly for the oxidation of about 250 ⁰ C. At this temperature the effect is. Presence of copper and vanadium catalytically in the process for cleaning the dicarbon the decarboxylation, especially of the adipic acid to form an acid mixture, must be taken into account that only by inhalation cyclopentanone. In addition, the greater degree of a short residence time and the specified residence time result in partial anhydration of the temperature range, the good yields of glutaric and succinic acid mentioned. This procedure can be achieved. If, on the other hand, the temperature deteriorates the yield considerably, if it is not exceeded, or if the residence time is exceeded, the harmful influence of the catalysts begins through a ^{treatment with} the decomposition of adipic acid and cyclopentanone before the distillation with cation exchange and the anhydration of glutaric acid and Bernschern turns off. For this, however, the melt must be stinic acid and so * a side reaction which leads to the dicarboxylic acids being dissolved in water, which leads to a lowering of the yield. If, on the other hand, the temperature to be distilled off again after the cation exchange is set too low, the return will be. This results in the process- ^{related 6} S proportion increased to 10% and above.
Standpoint energetic disadvantages. Also the attempt, the cleaned by the method according to the invention the dicarboxylic acids by means of a carrier gas overcharged dicarboxylic acid mixture can be used as an initial propellant, did not result in a technically viable solution, as a material for the manufacture of plasticizers or as a