HU194150B - Process for production of fumar acid from secondary products containing malein acid - Google Patents

Abstract

A process for the preparation of pure fumaric acid from a solution of maleic acid comprises purifying the solution by contacting with activated charcoal and isomerizing the maleic acid in the presence of this urea and Hcl and either NaHSO3 or Na2SO3.

Description

The present invention relates to a process for the preparation of pure fumaric acid from maleic acid-containing by-products which are formed during the production of phthalic anhydride or maleic anhydride.

Fumaric acid is a geometric isomer of melic acid and has similar chemical properties. Of the two isomers, fumaric acid is the more stable compound, so the conversion of maleic acid to fumaric acid begins at room temperature. In the industrial practice, isomerization is accelerated by raising the temperature and using catalysts.

Fumaric acid is used for many purposes. such as polyester resins, paints, varnishes, patterning powders, modified casting resins, electrochemical insulators, elastomers, paper plasticizers, etc. in animal nutrition and as a food additive to replace the more expensive tartaric and citric acids.

The starting materials for fumaric acid are melic acid and maleic anhydride. Maleic anhydride is produced by the catalytic oxidation of benzene, but is also a by-product in the manufacture of phthalic anhydride, naphthalene and naphthalene. in the catalytic oxidation of o-xylene. In the latter case, the fumes of maleic anhydride formed during oxidation are absorbed in water.

Of course, this maleic anhydride is contaminated with other by-products, which makes it difficult to process into fumaric acid. Such a waste washing liquid will generally contain 10-30% maleic acid, as well as organic oxidation products such as acids, aldehydes, quinones, etc., as well as condensation and polymerization products. In many places, these waste washing liquids are not recovered, leading to waste water and increasing environmental pollution. Their processing is therefore advisable for both environmental and economic reasons.

The present invention relates to the production of fumaric acid from industrial wastes containing maleic acid, which are naphthalene and naphthalene derivatives. They are formed during the production of o-xylene based phthalic anhydride and benzene based maleic anhydride.

Starting from pure maleic acid, the isomerization process is simple and the resulting fumaric acid usually does not require purification. However, when using wastewater containing maleic acid as a feedstock, the following problems arise:

- By-products in wastewater reduce the efficiency of the isomerization catalysts and may even react with the catalyst to create new impurities.

- Some of the contaminants in the waste water are trapped in the fumaric acid crystals formed, so the crude product needs to be purified.

In the known processes, the most common catalyst used is a bromine compound and an oxidizing agent, e.g. ammonium bromide and ammonium persulfate. In addition, urea, thiourea and its derivatives, hydrochloric acid and other nitrogen and sulfur compounds are used.

According to Polish Patent No. 57,076, a 40% solution of maleic acid in fumaric acid is first decolorized with activated charcoal in an autoclave, and if charcoal decolorization is not sufficient, it is followed by treatment with sodium hypochlorite.

Potassium bromate isomerised 100 ^e C catalyst. There is no data on the purity of the products.

U.S. Pat. No. 2,704,296 discloses the purification of the starting material by ldor treatment and charring prior to isomerization followed by isomerization for two hours in the presence of hydrochloric acid catalyst. The color of fumaric acid ranges from pale yellow to white.

During isomerization, they are oxidized with air after clarification of activated carbon according to U.S. Patent No. 3,256,327. The isomerization is carried out at 80 ° C in the presence of ammonium bromide and ammonium persulfate catalyst. The color of the product obtained corresponds to 45 Hazen numbers.

According to the following known procedures, the finished fumaric acid is subjected to a separate purification operation

After 1I:

According to Japanese Patent Application No. 37-6507 / 1962, a 10% aqueous solution of fumaric acid is prepared in the presence of activated carbon and manganese oxides. In this way, pure fumaric acid is obtained, the __ color number of which is not disclosed.

According to Japanese Patent Publication No. 48-34.121 / 1973, the finished fumaric acid is purified by sublimation, activated carbon clarification and crystallization. The color of the purified product on Hazenscale is 30.

According to US Patent 163,174, the solution of ma25 leic acid is isomerized first with urea followed by thiourea for three hours at 70 ° C. The fumaric acid is isolated and then recrystallized by charcoal clarification. Product purity is not reported.

According to Italian Patent Application 21,766 A / 81, the maleic acid solution is heat-treated at 100 ° C before isomerization and clarified with activated carbon. After filtration, they are isomerized with thiourea and the fumaric acid is isolated. The crude fumaric acid is recrystallized by activated charcoal clarification.

According to Japanese Patent Application 7330617, isomerization of maleic acid to fumaric acid is carried out in the presence of thio35 urea and hydrochloric acid or sulfuric acid. However, the purity of the product obtained is not satisfactory; if starting from solutions containing contaminated maleic acid, a separate operation is required for purification.

According to US Patent No. 279,818, ^L isomerization using thiourea + hydrochloric acid only yields pure fumaric acid starting from pure, colorless solutions. When starting from contaminated maleic acid solutions, the presence of thiourea and hydrochloric acid merely catalyzes the isomerization but is not suitable for purification.

The object of the present invention is to use a simple technology for the preparation of variously contaminated maleic acid-containing solutions into fumaric acid, whereby the isomerization is carried out rapidly and at relatively low temperatures and a pure final product is obtained.

According to the invention, fumaric acid is prepared from maleic acid-containing by-products by purifying the maleic acid-containing liquid with activated carbon and then isomerizing it in the presence of thiourea, hydrochloric acid and sodium sulfite or sodium bisulfite. The fumaric acid crystals from the solution are white in color and after drying correspond to the Hazan number 10. During the isomerization, the starting material is heated at 60-80 ° C for 30 minutes in the presence of an additive.

Advantages of the Invention:

1. Thiourea ♦ Hydrochloric Acid + Sodium Hydrogen Sul-21

The 194,150 fit system is a more effective isomeric catalyst than the known thiourea * hydrochloric acid system.

2. The procedure is simple and quick. The combination of purification and isomerization results in a simple technology g.

3. Additives are easily accessible and work well even in the presence of impurities.

4. A pure product having a color number of ca. 10 At her house. (In accordance with ASTM-D 1686-61) 10

Example 1

To 220 g of a brown wash containing 25% maleic acid obtained in the production of naphthalene-based phthalic anhydride, 3% by weight of activated carbon is added to the maleic acid content and stirred for 15 minutes at 90 ° C, cooled to 30 ° C and filtered. Then, 1.7% by weight of thiourea based on maleic acid content, 3.5% by weight of NaHSO3 and 15 ml of 301% hydrochloric acid are added to the solution. It is heated to 80 ° C and stirred at this temperature for 30 minutes, filtered to cool to 25 ° C and the wet fumaric acid is dried at 80 ° C.

Yield: 49.5 g, 80% of theory. Quality of the fumaric acid obtained: the acid content is 99.7-99.9% by weight, not containing maleic acid. 5% Abs. The color of its alcoholic solution corresponds to 10 Hazen numbers, the glow residue is 0.01% by weight, the iron content is below 3 ppm, mp 286.5-288.5 ° C. 25

Example 2

Brown maleic containing 220 g of 27 wt% wash liquor, which is formed in the p-xylene-based anhydride production based on contents of maleic acid 1.7% by weight of active carbon was added and stirred at 90 ^e C for 15 minutes, filtered, cooled to 30 ° . The solution is then treated with 1.7% thiourea based on maleic acid, 3.5% NaHSO ₃ and 10 ml <30% hydrochloric acid. After 30 minutes isomerization with constant stirring at 80 ° C, the precipitated fumaric acid was cooled to 25 ° C and filtered and dried at 80 ° C.

Yield: 54 g, 91% of theory. 5% by weight of abs. The color of its alcoholic solution corresponds to 10 Hazen numbers.

It has an acid content of 99.7% to 99.9% based on fumaric acid. 286-288 ° C.

Example 3

To 220 g of a brown wash liquid containing 27% maleic acid, which is formed during the production of benzene-based maleic anhydride, 5% activated carbon based on maleic acid is added and stirred for 30 minutes at 90 ° C and then filtered to 30 ° C. Then, 1.8% by weight of thiourea based on maleic acid content, 5% by weight of Na ₂ SO ₃ and 15 ml of 30% hydrochloric acid are added. After 30 minutes isomerization at 80 ° C with constant stirring, the precipitated fumaric acid was cooled to 25 ° C and filtered and dried at 80 ° C.

Yield: 53.3 g, 90% of theory. 5% Abs. The color of its alcoholic solution corresponds to 10 Hazen numbers.

It has an acid content of 99.7% to 99.9% based on fumaric acid.

Mp 286-288 ° C.

Claims (1)

Patent Claim Point Process for the preparation of pure fumaric acid from maleic acid by-products of naphthalene or o-xylene-based phthalic anhydride and benzene-based maleic anhydride in the presence of thiourea and hydrochloric acid, characterized in that the isomerization is in the range of 15 to 40% by weight Starting from solutions clarified with activated carbon, the solution is carried out in the presence of 2-8% sodium sulfite or sodium bisulfite, 4-8% hydrochloric acid and 1.2-2% thiourea, based on the maleic acid content at a temperature of 40-90 ° C. .