DE2016668A1 - Circular process for the production of tartaric acid - Google Patents

Description

The invention relates to a circular method of manufacture of tartaric acid by hydroxylation of maleic acid by means of an aqueous solution of hydrogen peroxide in the presence of tungstic acid as a catalyst.

is known to produce tartaric acid by a circular process * which consists of maleic acid to epoxysuccinic acid using an aqueous solution of hydrogen peroxide to epoxidize in the presence of tungstic acid as a catalyst, the epoxysuccinic acid to tartaric acid hydrolyze, crystallize the tartaric acid by cooling the reaction medium, separate it from the medium and to return the mother liquors from the crystallization to the epoxidation stage in order to repeat the cycle «

When recycling the mother liquors from the crystallization however, it was found that the rate of epoxidation is greatly reduced, and it has been found that this phenomenon can be attributed to tartaric acid which the recycled mother liquors are saturated.

As is well known, tartaric acid can also react with hydrogen peroxide to give formic acid and carbonic acid, which is detrimental to the overall yield of this process. .. ·. '■ ^ ____

009842/1939

An improvement that can be used within the scope of this process has now been found, which eliminates the tartaric acid, at which the mother liquors of the crystallization are saturated, made possible before their return and this with avoidance the simultaneous removal of the epoxidation catalyst.

The improved cycle process according to the invention consists in epoxidizing the maleic acid to epoxysuccinic acid by means of an aqueous solution of hydrogen peroxide in the presence of tungstic acid as a catalyst, hydrolyzing the epoxysuccinic acid to tartaric acid, cooling the reaction medium in order to crystallize the tartaric acid, which is then separated from this reaction medium, then to eliminate the tartaric acid, in which the mother liquors of the crystallization are saturated, by precipitation as an insoluble alkali or alkaline earth metal salt, and then to return these mother liquors, which contain the catalyst, to the epoxidation stage.

The remaining tartaric acid is preferably precipitated as acidic potassium tartrate or as calcium tartrate, which is then passed through Filtering or centrifuging a-b separates. These salts can used as such in the food industry, for example, or converted into tartaric acid.

The tartaric acid obtained according to the process of the invention can advantageously replace natural tartaric acid in most of its uses.

The main advantage of the invention is based on the fact that the Recirculation of the purified mother liquors, the epoxidation rate of maleic acid is significantly increased.

When carrying out the method according to the invention, ma: ι draws to achieve an optimal yield of tartaric acid and at the same time maximum utilization of the hydrogen peroxide propose to effect hydroxylation in two stages: the first is to convert maleic acid to epoxysuccinic acid by means of an aqueous solution of hydrogen peroxide in the presence

FROM Wolfr amaäure & Ί η gatftlvsatnr hei ™ i »-Hv

009842/1939

Temperature of the order of about 70 C too epoxidize, Ms the greater part of the hydrogen peroxide is consumed, and then in a second stage the To hydrolyze epoxysuccinic acid to tartaric acid, for example wise by heating the reaction medium to reflux temperature.

In practice, however, it is not possible to use the two stages strictly separate because part of the epoxysuccinic acid already hydrolyzed in the epoxidation reactor "

One cools, then the reaction medium to a sufficient one low temperature, preferably to about 0-5 ° 0j to precipitate the tartaric acid, which is obtained by centrifuging or filtering.

The mother liquors of the crystallization, which in dissolved Condition the catalyst tungstic acid, the rest of the tartaric acid and which contain unreacted maleic acid returned to epoxidation, wherever one goes fresh training on hydrogen peroxide and maleic acid or maleic anhydride will send to repeat the cycle.

In this cycle you can still see between 'the stages the hydrolysis and the crystallization an evaporation of part of the water present to the volume of the To keep the reaction environment at a constant value.

To carry out the process according to the invention, one can / Use hydrogen peroxide solutions of various concentrations; in practice, commercial solutions are used, for example from $ 30-70 advantageously used. The maleic acid can be in the form of its anhydride or the Acid or its acidic salts are added, the Amounts can amount to almost saturation in the medium at the epoxidation temperature.

As for the ratio of the reactants in the feed, so one can use a molar ratio of maleic acid / hydrogen peroxide work between 0.8 and 1.5. Since the water

009842/1939

2016688

Peroxide is the less stable reactant, however, preferred to have a surplus in relation to the stoichiomeiric Amount to apply.

Tungsten oxide, tungstic acid itself or their salts can be used as the tungstic acid catalyst. It is used in an amount of at least 0.5 and at most 5 Grew. #, Expressed as WCU, and based on the maleic acid present

The following test results and examples explain the invention and make it possible to better understand its scope

I. Influence of the concentration of tartaric acid present in the reaction medium on the speed of the Epoxidation of maleic acid

The tests were carried out under the same temperature conditions as in the production cycle, namely at 70.degree.

The results are shown in Table I.

009842/1939

Table I.

Sr.des Composition of the Incoming Leaking Solution
Test solution in g / kg

Reaction speed
^ ", . converted into moles

Maleic Wine Na ₂ WO .. Water Amount Concentration Concentration ^{* Maleic} Acid / ^{Ä /} Acid Acid _Ο ττ _Λ in g / h tion an · ———

anhydride

2H ₂ O

H ₂ O ₂ in

40.5 140.1

1.95 817.5

731
737

20.2 20.6

Tartaric acid
in g / kg

3.4
3.6

27.4 106

390 19.3

75 1.95 789.6 ^ _{21> 6}

75.2
75.5

0.478 0.501

40, 5 140.1 25th 1.95 792, 5 333 20.2 33 , 0 0.236 2 380 20.6 32 0.286 v! N
I. 27 4th 106 50 1.95 814, 6th 573 18.3 53 , 0 0.214 3 593 21.0 51 »9 0.211.

0.116 0.138

CD CD CD CO

II. Attempts at precipitation as acid potassium tartrate

The results of these attempts to precipitate the still in the Mother liquors of the crystallization tartaric acid as acidic potassium tartrate follow in Table 2 II.

Table II

No.·
the
try

Starting solution 1 kg

Tartaric acid
in moles

Maleic acid in moles

Neutralizing agent

KOH 1 N
in moles

Precipitation collected after 1 hour 30 min at 2-

KHC ₇₁ H. Or
4 4 6

0.427
0.427
0.427

0.715 0.715

in Molar-Jfe related moles to the used Tartaric acid

0.427
0.427
1.142

0.391 91.5
0.213 50
0.392 91.9

Since the neutral potassium tartrate is very soluble in the reaction medium, while the acidic potassium tartrate is very sparingly soluble, namely in the order of magnitude of 2.5 g / kg, one must exactly neutralize the first acidic function, as Axx did. experiment 5 shows.

When comparing experiments 6 and 7 it is found that the more acidic punctures than those of tartaric acid and in particular the first acid puncture of maleic acid, which did not react during epoxidation and which is in the mother liquor finds again, has to neutralize.

The results of this table show that by precipitation as acidic potassium tartrate, the tartaric acid, on which the mother liquors the crystallization at 2-3 ° C are saturated to more than can be eliminated.

III. Attempts to precipitate as oalcium tartrate .

A series of attempts to precipitate tartaric acid as calcium tertrates were carried out with a synthetic solution which only contained tartaric acid and tungstic acid »as a catalyst, the behavior of these two components when they are

009842/1939

ORIGINAL INSPECTED

are present to explore. The results follow in Table III. ■

00 984 2 / 1.9.3: 9

Initial solution

No. -

the tartaric acid-Na ₂ WO ₄ ter-. _0T r _n search in 10 "° ^ 2 ^ -3

Table III

Neutralizing agent

Ca (OH) ₂ in moles

Precipitation, collected after 1 hour "at barely temperature

weight
ⁱⁿ S.

CaWO

4H ₂ O

Total weight

weight

Molar ^ έ Molar ^ used tartaric acid

10
11
12th

53.3 53.3 53.3 53.3 53.3

26.6 53.3 26.6 53.3

53.3

53.3

53.3

106.6

106.6 13.55
13.65
13.80

21.55
28.75

100 99.4 99.0 63.6 48.3

0.4

0.6

33.4

47.8

97.8

98

98.6

99

100

0.8 0.5 94 90

00 ι

Relative to experiment 8, experiments 9 and show. 10 that it is possible. to precipitate calcium tartrate without precipitation of tungstic acid, if mole after mole tartaric acid by the basic agent is neutralized "

Experiments 11 and 12 show that it is possible then if desired, to precipitate the oalcium tungstate, which of It is important if the catalyst has lost part of its activity after several manufacturing cycles and you must reactivate it «.

The results of the experiments on precipitation as calcium tungstate the tartaric acid, which is present in the solutions obtained in practice, i.e. in the mother liquors of the crystallization, which also contains unreacted maleic acid during epoxidation ^ "follow in Table IV.

009142/1939 OhIOfMAL mSPECT £ D

Table IV

Starting solution 1 kg of neutralizing agent

Mr. the tartaric acid tests ^{in M} ° ^le * ^ _x . ^4H 2 °

in moles

in g of precipitate collected after 30 minutes
"at room temperature

^CaC0 3 solid in moles in moles Molar # based on the
tartaric acid used

XiX 13 T ^ yT 14

* | x 15 16

0.427

0.427 0.427

0.715 -

0.715 -

0.715

0.715

0.427

0.785 0.358 0.785 0.327
0.425

0.426

76.6
99.5

99.8

cn cn 09

Here, too, the experiments show that it is sufficient To neutralize the first acidic function of the maleic acid present, using the tartaric acid as oalcium tartrate to precipitate almost total effectiveness.

FIG. 1 shows an installation for continuous production of tartaric acid according to the inventive method, that is, with precipitation of the remaining in the Tartaric acid present in mother liquors ",

This system comprises a dissolving tank equipped with a stirrer, which at 1 is filled with maleic anhydride 2 is fed with water and at 27 with the returned mother liquors. The dissolution takes place at Room temperature.

The solution is fed via line 4 into a first Epoxyda- -tionsreaktor 5, which is provided with a stirrer and maintained at a temperature of ⁰ C .7O. This reactor 5 is fed at 6 with an aqueous solution of HpOp and is provided with a degassing line 7 to allow oxygen to be vented *

The reaction mixture goes through line 8 into a second Epoxidationsreakto3J9, where the epoxidation reaction takes place at 70 C is terminated. This reactor 9 is also with a Vent line 10 equipped, '

Through line 11 the reaction mixture enters the Hydrolysiergefäss 12 where the resulting epoxysuccinic wird.Da hydrolyzed at 102 ⁰ C to tartaric acid is carried out under reflux, the Hydrolysiergefäss 12 is equipped with a condenser 13 having an outlet 15 for air. The water vapor which condenses in 13 is discharged through line 14, allowing the solution to be concentrated at the same time.

The nydrolysierte mixture is conveyed via line 1t to the crystallizer 17 where it is cooled to ⁰ ° C. Then the slurry goes through line 18, through filter 19, while water is introduced through line 20 to the

0 0 9 8 4 2/1939

To wash precipitate from tartaric acid. This latter is sent via line 21 to a drying column 22, worii it is dried at 11O ⁰ C. The water vapor is removed via Leitui 23 and the dry tartaric acid obtained is removed via line 24.

The mother liquors saturated with tartaric acid leave the filter 4 <1 via line 25. They are collected in a precipitation vessel 29, into which the neutralizing agent is also sent via line 28. A vent 30 is also provided on the vessel 29.

The suspension formed in vessel 29 is conveyed via line 31 to a filter 33. At 32 this leads to the Washing the act defeat in needed water. The tartrate itself * is sent via line 34 to a drying column 35, from which water vapor via line 36 and the dry tartrate can be removed via line 37.

The mother liquors from filter 33, recovered via line 38, are subjected to purification at 26, a portion of which is removed, while the remainder is returned to the dissolving tank 3 via line 27.

FIG. 2 shows a plant operating according to the known method, that is to say without the remaining precipitates tartaric acid contained in the mother liquors. Parts 1 to 25 of the system are the same as those of Figure 1, but the mother liquors of the tartaric acid, which flow off by pipe, are immediately subjected to a purification at 26 and then returned to the dissolving tank 3 via line 27.

Examples.

In accordance with the method according to the invention, one works in a plant as described in FIG. 1, with precipitation the remaining tartaric acid dissolved in the mother liquors by the action of CaCO ,.

The composition of the reaction environment in the various Stages of the cycle are summarized in Table V below. The values are expressed in g / hour.

009842/1939

ORIOiNAL INSPECTED

Every hour, 3 261.5 g of maleic anhydride are introduced into the dissolving tank via line 1, 73, 6 g of water and 0.37 g of sodium tungstate dihydrate via line 2 and 657.5 g of returned Mother liquors via line 27 (see Table Y, column 1). In at the same time you pull from the dissolving container 3 from 993 g Solution (see Table V, column 2) to feed the reactor 5 in addition, via line 6 212 g of an aqueous Introduces solution from HpOp of $ 50. Reached 5 in this reactor the rate of epoxidation was 0.795 moles of maleic acid consumed per liter and per hour. Escape via line 7 2.8 g op / hour »-.

The emerging solution, namely 1202.3 g (see Table V, Column 3), goes into reactor 9, in which the epoxidation reaction completed. The rate of epoxidation reaches 0.376 moles of maleic acid consumed per liter and-per hour. 2.3 g of Og / hour escape via line 10.

The reaction mixture which leaves the reactor 9 at a rate of 1200 g / hour (see Table V, column 4) is sent through line 11 into the ^{hydrolysis container 12, which has been brought to 102 °} C. The water vapor condensed in 13 is removed from the circulation Line 14 eliminated in an amount of 280 g / hour, while via line 15 2.87 g of O ₂ / hour escape.

The hydrolyzed and concentrated mixture goes via line 16 into the ^{crystallizer 17, which is kept at 0} ° C., at a rate of 917 g / hour (see table Y, column 5), and then via line 18 to filter 19, where the precipitate also tartaric acid is washed with water, which is brought in via line 20 in an amount of 300 g / hour. The precipitate is then conveyed into the drying column 22, from which it is obtained via line 24 in a production rate of 339.1 g / hour.

The mother liquors, which are collected via line 25 in an amount of 767.7 g / hour (see Table V _9, column 6) , are passed into the precipitation tank 29, in which via line 2Θ,, 39 | ÖCg CaGOj / Stuilde can be added. At the same time 17.17 g QOo emitted via line 30 «Via line? 1

0098A2 / 1939

ORIGINAL

the suspension is sent to the filter 33 where the precipitate of calcium tartrate hydrate is washed with water injected through line 32 at a rate of 65 g / hour ₀

The washed precipitate is then ^{conveyed into the drying column 35, which operates at a temperature of 200 °} C., from which the anhydrous calcium tartrate is obtained via line 37 in an amount of 67.3 g / hour. The mother liquors exit the filter 33 via line 38 in an amount ^{o f} _A -JJ | £ j | 5 g / hour (s · Table V, column 7) and a Unacg are: at 26 subjected to, where to 10 removes $ ( see Table V, column 8), and the remainder is "" fed back into the dissolving tank 3 via line 27

The total molar yield ^, that is the ratio obtained Tartaric acid + calcium tartrate to consumed maleic acid is higher than

0098A2 / 1939

■■ ■ 1 - - Table V 2 t
3 4th 5.75 5 5.75 6th 7th 8th 7th 1
_k
VJl Number of the column - 339.5 0.31 I. Type of products
in ά / hour - 309.7 92.8 7.3 392.8 5.75 - - 37 Maleic acid 591.3 - 244.5 775.1 451.9 0.31 - - 69 Epoxidized Bern
stinic acid '- ■ - 2.8 6.1 - <· 53.7 - - 26th Tartaric acid 3.3 617.1 759.6 3.67 3.67 641.7 657 65, 02 water 60.2 - 36.4 60.2 60.2 - -. - hydrogen peroxide 2.37 3.67 3.67 . 2.37 2.37 3.67 3.67 Ö, O Na ₂ WO ₄ .2 H ₂ O 657.5 60.2 60.2 1200.0 917.0 60.2 66.9 6, 16668 Sour Cald? I £ m-
maleate 2.37 2.37 2.37 2.63 0, Acid Calcium
epoxysuccinate 993.0 1202.3 767.7 730.25 73, total ■ -

'-16-

Comparatively, the continuous production of Tartaric acid without precipitation of the tartaric acid contained in the mother liquor of the crystal, sation in a plant, as shown in the diagram shown in Fig. 2, performed.

The compositions of the reaction medium in the various stages of the cycle are summarized in Table VI below posed. The values are expressed in g / hour.

Each hour, 178.5 g of maleic anhydride were introduced into dissolving tank 3 via line 1, 305 g of water and 0.6 g of sodium tungstate dihydrate via line 2, and 529.2 g of recirculated mother liquors (see labeile YI, column 1) via line 27 At the same time, 1013.3 g of solution (see Table 0 VI, column 2) were withdrawn from the dissolving tank 3 and sent to the reactor 5. At the same time, 198 g of an aqueous solution of H ₂ O _{2 were introduced via line 6} ^νοη 50Ji,

In this reactor 5, the reaction rate is expressed in the consumption of maleic acid, 0.490 mol of maleic acid per liter and / hour "

11.2 g of O ₂ / hour, which resulted from the decomposition of the HgO ₂ , escaped via line 7.

The emerging solution in an amount of 1200 g / hour (see Table VI, column 3) is sent into the reactor 9, wherein the epoxidation reaction can be completed, with the rate of reaction there. 0.224 moles of maleic acid is which reacts per liter and per hour.

6.4 g of O ₂ / hour escape via line 10.

The reaction mixture, which emerges from reactor 9 in an amount of 1193 »6 g / hour (see Table VI, column 4), is conveyed via line 11 into the hydrolysis vessel 12 which has been brought ^{to 102 ° C.} The water vapor * condenses in 13 and is removed via line 14 at a rate of 516.9 g / hour, while 1.70 g of O ₂ / hour escape via line 15.

009842/1939

ORIGINAL INSPECTED

The hydrolyzed and concentrated mixture enters the crystallizer 17 at a rate of 675 g / hour (see Table YI, column 5) and the resulting slurry is filtered at 19, where the precipitate of tartaric acid with water in an amount of 300 g / Hour is washed i The precipitated tartaric acid goes into the dryer 22 _t from which it is obtained via funnel 24 in an amount of 249 g / hour, which corresponds to a molar yield of tartaric acid produced / maleic acid consumed of 97 fo .

The mother liquors in an amount of 638 g / hour (see Table VI, column 6) leave the filter 19 via line 25. At 26 you eliminate $ 17, that's 108.7 g (see Table VI, column 7), and the remainder is via line 27 returned to the dissolving container 3.

009842/1939

CD CO CD

1 Tabel 3.6 VI 3 , 9 4th 5 5 3, 5 6th 5 7th - VJl I. O Number of the column 2 1013.3 2 675, 2 2 0, 2 —J.
OD CD Type of products , 5 108 I. CD in g / hour 66 144 79 8th . 79 9 79 6th 13, 4th CD Maleic acid 1 277.5 150 222 8th 1, 8th 1, 1 0, CO Epoxidized amber 1 6th 7th acid 31.2 31.2 33 , 0 35, 6th 286, 6th 37, 6th 6, 6th Tartaric acid 428 832 848, 6th 303, 0 516, 0 88 , 7 •Water - 700 36 3, - - Hydrogen peroxide 3 - 3, 3, 3, Na ₂ WO ₄ .2 H ₂ O 529.2 1200 1193 638, total •

Claims (3)

/ 1J circular process for the production of tartaric acid, thereby ■ marked that one can use maleic acid Epoxysuccinic acid using an aqueous solution of Hydrogen peroxide is epoxidized in the presence of tungstic acid as a catalyst, the epoxysuccinic acid is hydrolyzed to tartaric acid, the reaction medium cools to form tartaric acid to crystallize, which is separated from the reaction medium, then by precipitation as insoluble alkali or ' Alkaline earth salt removes the tartaric acid, which the mother liquors of the crystallization are saturated with, before they are used mother liquors containing the catalyst into the epoxidation stage returns. 2 ο method according to claim 1, characterized in that the tartaric acid to which the mother liquors the crystallization are saturated by precipitation as Calcium tartra.t eliminated 3 ο method according to claim 1 ,. characterized, that the tartaric acid, in which the mother liquors of the crystallization are saturated, can be treated as acidic by precipitation Eliminates potassium tartrate. 009842/1939