Method for manufacture of products containing disalts of formic acid

The present invention relates to a process for the preparation of products containing double formic acid salts. The products are made from potassium, sodium, ammonium and cesium compounds and formic acid containing 0-50% water in a reactor at 40-100 ° C.

It is often desirable to produce products with a high concentration of monocarboxylic acid salts. Such products can be used for a variety of purposes. For example, formate-based animal feed additives require high concentrations of formate and the product does not release acids that cause corrosion and may cause poor working conditions during product manufacture and transport.

To obtain such concentrated products, at least a portion of said acid mono-salts may be replaced by double salts, such as diformates.

The mono- salts of potassium, sodium, ammonium and cesium form double salts with monocarboxylic acids such as formic and acetic acids. The durability of salt bonds decreases from cesium / potassium to ammonium. Potassium diformates are stable crystalline salts which decompose above 120 ° C. Ammonium diformates are less persistent than potassium diformates and the decomposition temperature of ammonium diformate is considered to be 2530 ° C. Sodium diformates decompose at 100-120 ° C.

Gmelins Handbuch der anorganischen Chemie (Gmelins Handbook of Inorganic Chemistry), 8. Ed. System No.21 and 22, Verlag Chemie GMBH, Berlin 1928, pp. 818-857 and pp 919-949, respectively, describe the formation of double salts of C4-monocarboxylic acids, such as potassium and sodium diformates, by dissolving pure formates in anhydrous concentrated formic acid. As described above, crystals of needle-like diformates, etc., are obtained in laboratory experiments. The method for obtaining double salts described by Gmelin is purely theoretical. The commercial production of these double salts is not reported.

GB Patent Nos. No. 1505388 describes the formation of aqueous complex solutions of salts from ammonium and / or from metal ions selected from groups I and II of the periodic table and from at least one of the carboxylic acids. The chemical equivalent ratio of the acid to ammonium and / or metal ions is between 2: 1 and 4: 1. The water content of the aqueous solution is 15-75% by weight of the total composition. Said solution of complex carboxylic acid salts or double salts has been found to be a preservative composition suitable for animal signature. This patent does not provide any other conditions for the preparation of complex salt solution and dry salts.

The main object of the present invention is to provide a novel process for the preparation of products containing double formic acid salts which can be obtained in large quantities in a commercial product.

Another object of the invention is to obtain thermally stable products containing formic acid, i.e., products with the lowest acid loss. A further object of the invention is to obtain a crystalline or granular product which is bulk and has good storage properties.

Yet another object of the present invention is to provide a product with a very low water content which is less hygroscopic than the carboxylate itself. Sodium and potassium diformates have been found to be particularly potent in these latter properties.

Another object was to produce concentrated solutions or suspensions of double formic acid salts.

Crystalline diformates are prepared using potassium hydroxide, carbonate, bicarbonate or formate, sodium hydroxide, carbonate, bicarbonate or formate, cesium hydroxide, carbonate, bicarbonate or formate or ammonium formate or ammonia mixed with 0-30% aqueous formic acid. The resulting crystalline diformates are easily separated from the suspension by centrifugation as a solid phase and the filtrate containing the acid salts is collected. The separated solid phase was then transported to a dryer / mixer by a belt / bucket conveyor. The wet diformate product is dried to a water content of <0.2%. Calcium or other formates may be added to the dryer / blender. For further dehydration of the diformates, a dryer may be added to the dryer / mixer. Suitable dryers are various types of quartz, starch, etc. One of the recommended quartz dryers is sold under the trade name Sipernat 50/22 S. The resulting crystalline diformates are bulk, dry, stable, i.e., they are very slightly degraded to acid and formate at normal storage temperature (0-80 ° C). Thus, the inventor has found that, when working on the above ideas, the double salts of formic acid can be obtained as follows: K-, Na-, Cs- or NH₄- formate, K-, Na-, or Cs- carbonate or bicarbonate is mixed in the reactor with 0-50% aqueous formic acid at 40-100 ° C. The reaction is carried out up to 50-55% acid. The mixture is then cooled and the resulting suspension filtered, the filtrate collected or recirculated, and the double salt separated solid phase transported to a dryer / blender, where the double salts are dried. Optionally, other double salts, calcium / magnesium salts and / or desiccant may be added to the dryer / blender. Filtration is preferably by centrifugation.

Preferably K-, Na- or NH₄- molar ratio of formate to formic acid:

1-1.5: 1-1.5. The temperature in the reactor is preferably 50-70 ° C and the acid concentration is 50-100%.

K / Na carbonates / hydroxides can be used in solid form and containing

1-15% by weight of water.

Na- or K-diformates can be produced using only formic acid and NaOH or KOH as raw materials. Optionally, Na- or K-carbonates may be used together with the corresponding hydroxides. This process consists of reacting 80-95% aqueous formic acid solution with 70-80% potassium or sodium formate solution at 50-60 ° C in the first reactor and then cooling the resulting mixture to 20-25 ° C to form diformate. settles down. The diformate-containing suspension is separated and the separated liquid phase is transferred to a second reactor, where it is treated with 50% NaOH or KOH solution, which can optionally be mixed with the corresponding alkali metal carbonate. The formate solution thus prepared is adjusted to pH = 9-10, then the solution is evaporated to 70-80% and transferred to said first reactor. The separated diformate solid phase is air-dried to <0.2 wt% water in a dryer.

New products made as described above include:

double salts of formic acid containing:

20-60% by weight of potassium diformate,

20-50% by weight of sodium di / tetraformate,

0-25% by weight of calcium monosodium salt,

0-4% by weight of desiccant,

0-5% by weight of water.

Another similar product according to the invention consists of the following components:

60-99% by weight of potassium diformate,

0-28% by weight of mono-calcium calcium,

0-4% by weight of desiccant,

0-5% by weight of water

Yet another product is concentrated in double formic acid salts o

solution containing 55-70% by weight of diformates.

The scope of the invention is defined by the following definition of the invention.

The invention will now be described and explained in the form of drawings and examples illustrating the production process.

Fig. 2 is a diagram showing the manufacturing process for products containing double formic acid salts.

Figure 3 shows a scheme for the production of potassium or sodium diformates.

Figure 1 shows a process for the production of products containing double formic acid salts. Potassium hydroxide, carbonate, bicarbonate or formate, sodium hydroxide, carbonate, bicarbonate or formate, cesium hydroxide, carbonate, bicarbonate or formate or ammonium formate or ammonia 1 and 2 are mixed with formic acid 3 to which is added a little water 4. tanks 5 and 6 with agitator at 40-100 ° C, preferably 50-70 ° C. The reaction mixture is cooled to 20-40 ° C. The double salts are precipitated, the resulting slurries 7 and 8 are centrifuged 9 and centrifuged. Separated solid phase 10 and 11 containing diformate crystals are transported by belt / bucket conveyor 12 to dryer / mixer 13. To formers such as calcium formate 14 and / or dryer 15 may be added to dryer / mixer 13. Initially, calcium formate -14 and dryer 15 are introduced into bins 16 and 17. Product 18 is taken from dryer / mixer 13. Filtrates 19 and 20 are taken from centrifuges

9th Said filtrates can be further used as concentrated solutions containing 55-70% of double salts, or may be further processed. Suspensions 7 and 8 can be diluted, if necessary, by draining filtrate 19 and 20 from centrifuges 9 into reaction tanks 5 and 6.

Figure 2 illustrates the preparation of double salts of Na or K by reaction in two reactors 21, 22. In reactor 21, 80-95% formic acid 3 is reacted with reactor 22 70-80% Na / K formate at 50-60 ° C. 23. The resulting solution is cooled to 20-25 ° C. A coarse, crystalline mass of diformate is formed and precipitated. Depending on the temperature of the final cooling stage, this suspension contains 40-45% solids. The crystalline mass 24 of the diformate is transferred to a separation device 9, preferably to a pusher centrifuge designed to pass through crystals of less than 70 microns. Therefore, the crystalline mass D₅₀ will be about 600 microns. This produces a dust-free product. The filtrate 25 with water-dissolved diformate and a small amount of crystals is pumped to reactor 22 where the acidic part is neutralized with 50% NaOH or KOH solution 26. Alternatively, a combination of the corresponding carbonates and 50% hydroxide solution can be used. During neutralization, the crystals in solution dissolve. After the solution 27 reaches a pH of 9-10, it is concentrated in an evaporator 28 to which the vapor 29 can be fed. The thus concentrated 70-80% solution 23 is transferred to the reactor 21. The crystalline mass of diformate 30 containing about 1-1.5% by weight of water is transferred from the separator 9 to a dryer 13, preferably a fan dryer. The diformate in the dryer 13 is dried for 12-18 minutes until the water content in it is reduced to <0.2% by weight with an air stream 31 passing through 32. The thus-dried product 18 can be mixed with a dryer.

example

The following example shows the production of potassium diformate.

% KOH and 85% formic acid in a water-cooled reaction tank / crystallizer blender are stirred at 60-70 ° C until about 50-55% formic acid is recycled. The reactor is cooled to 20-40 ° C. The potassium diformate is quantitatively precipitated to form a suspension with approximately 50-55% of the dry product. The suspension is continuously centrifuged to 1.5-3 wt% water. The resulting solid mass is conveyed to a dryer / mixer by a conveyor belt / scoop conveyor to give a dry product with approximately 0.1% w / w water. The formic acid content is about 35%. Other diformates, dry formates and / or desiccant may also be added to their dryer / blender. The filtrate from the centrifuge can be used to dilute the suspension before centrifugation if necessary. The filtrate taken up can be further processed by adding potassium hydroxide to it. The formic acid present in the filtrate is converted into a solution of potassium formate.

Optionally, potassium diformate may be prepared in the same manner from 85-95% formic acid and 75% potassium formate.

example

The following example shows the production of sodium di / tetraformate.

In a water-cooled reaction tank / crystallizer containing a stirrer at 60-70 ° C, 80-90% formic acid is mixed with 97% NaOH dry matter until about 50-55% formic acid is recycled. The reactor is cooled to 20-40 ° C and the resulting mixture of sodium diformate and trisodium tetraformate is quantitatively precipitated to give a suspension of about 50%. Centrifuge the suspension to approximately 2-5% water. The resulting solid phase is conveyed to a dryer / mixer by a conveyor belt / bucket. The contents are dried in a dryer / blender. It will contain about 30% formic acid. Other diformates, dry formates and a desiccant can also be added to the dryer / blender.

The centrifuge filtrate may be used to dilute the suspension before centrifugation if necessary. The collected filtrate may be further treated in the same manner as in Example 1.

Sodium diformate / trisodium tetraformate may optionally be prepared by dissolving sodium formate in 85-95% formic acid in a molar ratio of about 1: 1. The suspension should be diluted from the centrifugation operation with the recirculating filtrate. In this case, the separated solid phase is washed continuously with a small amount of dilute NaOH to neutralize the excess acid.

example

This example illustrates the production of dry bulk products with high potassium diformate and sodium diformate / tetraformate. These product types are referred to herein as Type 1 products.

Potassium diformate and sodium diformate / tetraformate are prepared as shown in Examples 1 and 2. Calcium formate, desiccant, quartz material sold under the trade name Sipernat 50/22 S and water are added to their dryer / mixer. The composition of the mixture in the dryer / mixer is:

potassium diformate 49.3 wt% sodium diformate / tetraformate 24.6 wt% calcium formate 24.6 wt% dryer 1.0 wt%

H₂O 0,5% by weight

The product obtained has the following general composition by weight:

<td>formic acid</td><td> 22,4</td><td> %</td>

<td>potassium formate</td><td> 31,9</td><td> %</td>

<td>calcium formate</td><td> 24,5</td><td> %</td>

<td>sodium formate</td><td> 19,7</td><td> %</td>

<td>dryer</td><td> 0,5</td><td> %</td>

<td>H₂O</td><td> 1,0</td><td> %</td>

The product contains about 20% formic acid and about 64.8% formate. Similar type 1 products may be prepared as described in Example 3. The total concentration of formate (propionate, etc.) is very high due to the high double content of monocarboxylic acid. The amount of calcium formate / acetate / propionate added will depend on the actual use of the type 1 product. When the acid used is formic acid, the total composition by weight of type 1 products will be:

<td>potassium diformate</td><td> 20-60 %</td>

<td>sodium di / tetraformate</td><td> 20-50 %</td>

<td>calcium formate</td><td> 0-25 %</td>

<td>dryer</td><td> 0-4 %</td>

<td>water</td><td> 0-5 %</td>

The main area of ​​application is feed additives.

example

This example illustrates the production of dry bulk products with high potassium diformate content. These types of products are referred to herein as Type 2 products.

Potassium diformate was prepared as shown in Example 1. calcium formate, dryer and water are added to the dryer / bag. The mix composition in the dryer / mixer was:

potassium diformate calcium formate dryer H₂0

88.0 wt% 11.0 wt% 0.5 wt% 0.5 wt%

The product obtained has the following general composition by weight:

<td>formic acid</td><td> 31,1</td><td> %</td>

<td>potassium formate</td><td> 56,9</td><td> %</td>

<td>calcium formate</td><td> 11,0</td><td> %</td>

<td>dryer</td><td> 0,5</td><td> %</td>

<td>H₂O</td><td> 0,5</td><td> %</td>

The product contains about 30% formic acid and about 65.6% formate. When the acid used is formic acid, the total composition by weight of the type 2 products prepared as described above will be as follows:

potassium diformate 60-99% calcium formate 0-28% water 0-5% desiccant 0-4%

The main area of ​​application is feed additives.

example

This example illustrates the preparation of potassium diformate according to the process shown in Figure 2.

In the first reactor 21, 85% formic acid interacts with 75% potassium formate at about 55 ° C and then cools to 20-25 ° C, thereby precipitating a coarse mass of potassium diformate crystals. The diformate is separated by centrifugation and then contains 1-1.5% water. It was further dried in a dryer to &lt;0.2% water. The potassium diformate containing a small amount of crystalline filtrate is pumped to the second reactor 22 where it is treated with 50% potassium hydroxide solution, thereby neutralizing the acidic portion of the diformate. The solution is brought to pH = 9-10 and then the solution is evaporated to 75% potassium formate which is transferred to 21 reactors. in the dried potassium diformate, 1-1.3% of the Sipernat desiccant - silica was added.

In the neutralization stage, sufficient potassium is fed to the second reactor to provide the required potassium mass balance. Therefore, there is no need to feed potassium formate externally into this process, requiring only formic acid and hydroxide, which can optionally be mixed with the corresponding alkali metal carbonate. Made in bulk, dust-free, ready to bag or bulk delivery.

The production process of the present invention is flexible and economical and can produce a wide range of products with a high concentration of formic acid salts, especially double salts. The resulting basic products are dry, bulk, have excellent storage properties, have very low water content and are thermally stable, i.e., have very low acid loss. In addition, the filtrate secondary product, according to the process shown in Figure I, can be used as such or recycled to the production process of the parent product.