DE1290928B - Process for the recovery of the catalyst from the mother liquors in adipic acid production - Google Patents

Description

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The invention relates to a method for steaming, whereby a selective precipitation of the Recovery of the catalyst from most of the mother vanadium from the evaporation liquors the production of adipic acid is made possible by nitric residue when diluted, is based, Acid oxidation of cyclohexanol and / or The precipitated vanadium compounds are then Cyclohexanone filtered off in the presence of a copper vanadium 5, dissolved again in nitric acid and the mixed salt catalyst. pitric acid oxidation fed back. The copper

A known technical process for compounding is by treating the mother liquor Position of adipic acid, a valuable and in the vanadium precipitation with a cation exchange large Extent of the fabric used, runs in resin recovered. This procedure requires more Stages: First, the oxidation of cyclohexane in io but the costly stage of evaporation of the liquid phase with air or another acidic adipic acid mother liquor.

substance-containing gas to a mixture of cyclo- While it is known that cation exchange

hexanol and cyclohexanone with fairly low resins for the removal of copper ions from the degree of conversion, However, high yield, second solutions can be used, were all up-separating of the unoxidized cyclohexane from 15 previous attempts with regard to the removal of the cyclohexanol-cyclohexanone mixture, thirdly, vanadium ions on the use of anion further oxidation these intermediates are directed with salt exchange resins, since vanadium is aqueous pitric acid to adipic acid and small amounts of solution are usually in anionic form (cf. other dicarboxylic acids, such as glutaric acid and amber- "Industrial and Engineering Chemystry", Vol. 35 stinic acid, and fourthly, isolation of adipic acid ao [1943], pp. 861 and 862). If one suggests, off this acid mixture. The nitric acid oxidation alternates between cation and anion exchangers can according to British Patent 572 260 with recovery of a mixture of copper and Use of a mixed catalyst that is made up of Vana vanadium compounds from their solutions. and copper compounds are composed, a cation must be used. The adipic acid crystallizes from the oxy-exchange resin alone to form an effective rewinding mixture and is initially made of a mixture of valuable components from the mother liquor severed. In the mother liquor, valuable catalyst components are not feasible, if not impossible, as anator components and contain carboxylic acids. To be seen so far.

determined the economics of the process that was contrary to previous experience

part of the mother liquor was discarded as waste, 30 now found that with an appropriate selection of one for example by burning off the remaining oxidation-resistant cation exchanger and one Hydrocarbons, with valuable catalyst- suitable control of the concentration and des metals were lost. the pH value of a vanadium and copper ion

When using vanadium as a catalyst-holding solution, both components are more economical component was z. In U.S. Patents 35 ways using a single ion output 2 439 513 and 2 557 282 suggested that this can be recovered by exchangers. Adjusting the pH of the mother liquor to a The method according to the invention for re-

Recover value above 1.0 with an inorganic base, such as recovery of the catalyst from the mother liquor sodium carbonate or hydroxide. the production of adipic acid by nitric acid oxy-The vanadine-containing complex compound, whose or- 40 dation of cyclohexanol and / or cycloganic component probably from one or hexanone in the presence of a copper-vanadium mixed several dicarboxylic acids, for example glutaric acid, catalyst is characterized by the fact that succinic acid and or adipic acid consists of mother liquor after the pH has been adjusted and which precipitates here can be filtered off and returned to the salt-0.3 to 1.8 with an oxidation-resistant pitric acid oxidation. However, cation exchange resin, which from the water is added to the system in the form of foreign substances of a crosslinked sulfonated vinylaryl polyion, which results in considerable absorption, results in operational difficulties at a temperature of 33 to. 90 ⁰ C treated, the salt freed from the metals

From British patents 756 679 and peter-acid lye separates from the ion exchanger and 230 it is known that the mother liquor sulfuric acid 50 removes the adsorbed metals with nitric acid from the add and heat the mixture obtained until the ion exchanger elutes.

essentially the total amount of nitric acid.

and water has evaporated from it. Afterwards, it is necessary for the pH of the vanadium to separate the catalyst components obtained as residue and the solution containing copper in ionic form and the by-products from one another. This 55 does not exceed or fall below a certain limit. The mode of operation is also unsatisfactory, since if the pH value is more than 1.8, a foreign substance is again reduced here in the system, namely the recovery of vanadium. In aqueous solutions, which also require expensive measures, which have a pH value of 1.8 or less, the catalyst constituents must be separated from the, presumably almost the total amount of by-products. If the re-60 of the vanadium as the vanadyl cation VO ₂ ⁺ before. extraction of the valuable copper and vanadium to reduce the degradation of the resin

Compounds by evaporation of the mother liquor pH of the solution not less than -0.3, Tried to dryness will find a lively and The vanadium content of the solution to be treated

therefore dangerous oxidation reaction takes place. may depend on the type of used

Finally, there was a method of resin, the rate of ion exchange recovery of vanadium-copper mixed catalysts and other process conditions vary greatly, Suggested this on reducing saltpetre- However, the best results are obtained when Acid content of the adipic acid mother liquor by adding about 0.05 to 1.5 percent by weight of vanadium

contains as ammonium metavanadate. The concentration the copper in the solution is preferably about 0.16 to 5.0 percent by weight and that of nitric acid up to 20 percent by weight.

The eluate of the ion exchanger can oxidize nitric acid be fed back.

The process according to the invention can be carried out continuously, with the mother liquor flows through a first chamber containing the cation exchange resin. According to a predetermined Time or a predetermined throughput of mother liquor becomes the feed to the first chamber turned off and fed to a second chamber containing the same cation exchange resin. As soon as the mother liquor has passed through both chambers, dilute nitric acid is left as the eluent flow through the first chamber to remove copper and vanadium from the resin in the first chamber. As soon as the flow to the second chamber is shut off, the liquid is through the first Chamber passed which contains the regenerated cation exchange resin. The alternating sequence of Adsorption and elution of the ions can continue as long as necessary.

The cation exchange resin used in the process according to the invention preferably consists of a mixture of a sulfonated polyvinylaryl compound with a divinylaryl compound, the SO ₃ H residue providing the available hydrogen. In particular, sulfonated polystyrene crosslinked with various amounts of divinylbenzene can be used. Suitable resins are e.g. B. the exchangers known under the trade name "Amberlite IR 120" and "Amberlite 200", sulfonated cation exchange resin based on styrene (known under the trade name "Permutit Q") and synthetic resin ion exchangers made from styrene-divinylbenzene copolymers with exchangeable groups (under the trade name "Dowex 50 «known). These resins are available as pearl-like grains and are well suited for use in the method according to the invention. The degree of networking is important. The preferred degree of crosslinking is about 8 to 16%, ie the divinylbenzene is preferably used in the preparation of the polymer in an amount of 8 to 16%, based on the weight of the styrene plus divinylbenzene.

The invention is explained in more detail below using an example. Parts and percentages are on Based on weight.

example

An adipic acid mother liquor, which is used in nitric acid oxidation, was used as the feed material of cyclohexanol and / or cyclohexanone in the presence of a copper-vanadium catalyst accrued and from which the adipic acid had crystallized and separated. she got then concentrated further, diluted with water, cooled and adipic acid which crystallized out again was removed.

The mother liquor contained 6.42 percent by weight of nitric acid, 30 percent by weight of dicarboxylic acids, 0.21 percent by weight copper as nitrate and 0.12 percent by weight vanadium as ammonium metavanadate, Rest water.

The method will now be explained in more detail with reference to the drawing: 6000 parts by weight of mother liquor, a temperature of 60 dz 5 ° C and a pH of 0 possessed were of a sleeve provided with a temperature control device container A continuously through a column I, 2000 Parts of a cation exchange resin (trade name "Dowex 50 χ 8") contained, passed within a period of 43.5 minutes. A further part of the mother liquor was then passed through column II in the same way. The effluents from Columns I and II were fed to a tank B containing the same kind of resin. While the mother liquor was flowing through column II, dilute (10%) nitric acid from container S was passed through column I, and the eluates were collected in container R after passing nitric acid also through column II. It was found that about 95% of the copper and 75 to 80% of the vanadium was recovered by adsorption on the cation exchange resin with subsequent elution by the dilute nitric acid.

In the same way, excellent results have been obtained using resins other than those below the trade names “Dowex 50 χ 12”, “Dowex 50 χ 16”, “Permutit Q”, “Amberlite 200” and "Amberlite IR-120" known exchangers. The effectiveness of the resins in terms of vanadium recovery showed that "Amberlite IR-120" was comparable to "Permutit Q" and "Dowex 50 χ 8", each of which was slightly better than "Dowex 50 χ 12", "Dowex 50 χ 16" and "Amberlite 200".

The recovered mixture of vanadium and copper compounds can be oxidized with the usual nitric acid of cyclohexanol and / or cyclohexanone can be reused as a catalyst. There could be no significant differences between oxidations carried out with recovered and with fresh mixed catalyst, to be observed. The oxidation proceeded normally and gave approximately equal yields of adipic acid.

The method according to the invention has numerous advantages. This is how the valuable mixture is made Copper and vanadium compounds that were previously normally lost are easily recovered. Further the mixed catalyst is recovered in high purity and activity.

Claims (3)

Patent claims: 1. A process for recovering the catalyst from the mother liquors of the adipic acid production by nitric acid oxidation of cyclohexanol and / or cyclohexanone in the presence of a copper-vanadium mixed catalyst, characterized in that the mother liquor after adjusting the pH to -0.3 to 1 , 8 with an oxidation resistant cation-exchange resin consisting of the hydrogen form of a cross-linked sulfonated Vinylarylpolymerisats treated at a temperature of 33 to 9O ⁰ C, freed from the metal nitrate liquor separated from the ion exchanger and eluted the adsorbed metals with dilute nitric acid from the ion exchanger. 2. The method according to claim 1, characterized in that there is a cation exchange resin used, which consists of the hydrogen form of a sulfonated polystyrene, which in an amount of about 8 to 16%; based on the weight of the resin which is crosslinked with divinylbenzene. 3. The method according to claim 1, characterized in that the mother liquor to be treated about 0.05 to 1.5 weight percent vanadium as ammonium metavanadate, about 0.16 to 5.0 weight percent Contains copper as nitrate and up to 20 percent by weight nitric acid. 1 sheet of drawings