Method for preparing potassium diformate from low-concentration formic acid

Abstract

The invention relates to a method for preparing potassium diformate from low-concentration formic acid, which comprises the following steps: adding a formic acid solution with the concentration of less than 10% into potassium hydroxide while stirring at room temperature, and stopping stirring after the temperature of a solution system is reduced to room temperature; and carrying out reduced pressure evaporation on the solution system, and drying to obtain the potassium diformate. According to the method, low-concentration formic acid is used, so that the intensity of acid-base neutralization reaction can be effectively reduced, heat release is slow, formic acid volatilization is avoided, and the yield of potassium diformate is increased; the potassium diformate is prepared from low-concentration formic acid which does not have economic benefits, so that waste is turned into wealth; meanwhile, reduced pressure distillation is adopted, so that energy consumption is reduced, and corrosion to equipment is also avoided by using low-concentration formic acid.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of potassium diformate, and in particular to a method for preparing potassium diformate by using low-concentration formic acid. Background Art

[0002] Potassium diformate is an organic acid salt. It is a white crystal or crystalline powder formed by hydrogen bonding between a molecule of formic acid and a molecule of potassium formate. It is easily soluble in water, with a molecular formula of HCOOH·HCOOK and a molecular weight of 130.14. Potassium diformate has the effects of resisting bacterial infection, improving feed digestibility, and promoting growth.

[0003] At present, the synthesis of potassium diformate is mainly synthesized with 80-90% formic acid. For example, the patent with publication number CN117886689A discloses a method for preparing potassium diformate, wherein an aqueous solution of glyoxal and an aqueous solution of potassium permanganate are mixed to carry out an oxidation-reduction reaction; the product system obtained by the oxidation-reduction reaction is sequentially concentrated, crystallized and filtered; the solid phase obtained by filtration is manganese (II) formate dihydrate; the filtrate obtained by filtration is mixed with a formic acid solution, and a synthesis reaction is carried out to obtain potassium diformate; the mass concentration of the formic acid solution is 80-90%. Using 80-90% formic acid is not only costly, but also 80-90% formic acid is added to the reactor, and the acid-base neutralization reaction is highly exothermic, which can easily volatilize the formic acid due to heat, resulting in the loss of formic acid, resulting in a relatively low yield of potassium diformate, and high concentrations of formic acid will corrode pipelines. Moreover, as an important chemical product, formic acid is widely used in various industries. At present, there is a relatively mature technology for producing formic acid by electro-reduction of carbon dioxide. However, as the operation time of the reactor increases, the purity of the produced formic acid will decrease accordingly. If the formic acid is simply purified, the energy consumption is high, the recovery rate is low, and the pollution is serious. Therefore, producing potassium diformate from low-purity formic acid is a method to reduce energy consumption and increase economic benefits. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a method for preparing potassium diformate from low-concentration formic acid, which can prepare potassium diformate from low-concentration formic acid that does not have economic benefits, thereby turning waste into treasure; using reduced pressure distillation to avoid high-temperature distillation reduces energy consumption, and the participation of low-concentration formic acid in the reaction also reduces the corrosion of strong acid to equipment.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention first provides a method for preparing potassium diformate from low-concentration formic acid, which comprises the following steps: adding a formic acid solution with a concentration of less than 10% to potassium hydroxide under stirring at room temperature, and stopping stirring after the temperature of the solution system drops to room temperature; evaporating the solution system under reduced pressure, condensing and recovering formic acid, and drying and crystallizing to obtain potassium diformate.

[0006] On the one hand, the invention uses low-concentration formic acid, which can effectively reduce the intensity of the acid-base neutralization reaction and release heat slowly, thereby avoiding the volatilization of formic acid and improving the yield of potassium diformate; on the other hand, low-concentration formic acid without economic benefits is used to prepare potassium diformate, thereby turning waste into treasure; at the same time, reduced pressure distillation is adopted to reduce energy consumption, and the use of low-concentration formic acid also avoids corrosion to equipment.

[0007] As a further improvement of the above scheme of the present invention, the concentration of the formic acid solution is 3% to 10%.

[0008] As a further improvement of the above scheme of the present invention, the concentration of the formic acid solution is 5% to 10%.

[0009] As a further improvement of the above scheme of the present invention, the molar ratio of formic acid to potassium hydroxide is 2-3:1.

[0010] As a further improvement of the above scheme of the present invention, the stirring time is 1h~3h.

[0011] As a further improvement of the above scheme of the present invention, the pressure of the reduced pressure evaporation is -0.05MPa~-0.1MPa.

[0012] As a further improvement of the above scheme of the present invention, the temperature of the reduced pressure evaporation is 50-80°C.

[0013] As a further improvement of the above scheme of the present invention, the formic acid solution obtained by the reduced pressure evaporation is recovered.

[0014] As a further improvement of the above scheme of the present invention, the drying is carried out at 50-80° C. for 5-8 hours.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The method for preparing potassium diformate from low-concentration formic acid of the present invention, on the one hand, uses low-concentration formic acid, which can effectively reduce the intensity of the acid-base neutralization reaction and release heat slowly, thereby avoiding the volatilization of formic acid, thereby increasing the yield of potassium diformate, and the yield of potassium diformate reaches more than 85%; on the other hand, low-concentration formic acid that does not have economic benefits is used to prepare potassium diformate, thereby turning waste into treasure; at the same time, vacuum distillation is adopted to reduce energy consumption, and the use of low-concentration formic acid also avoids corrosion to equipment.

[0016] 2. During the reduced-pressure evaporation, the evaporated formic acid is cooled and recovered, thereby preventing the vapor containing formic acid from being discharged into the atmosphere and causing air pollution. The formic acid recovery rate of the reduced-pressure evaporation of the present invention reaches more than 90%, and the formic acid content in the recovered formic acid solution reaches more than 0.8%. The recovered formic acid can be used again to prepare potassium diformate, so that low-concentration formic acid can be fully utilized, energy saving and emission reduction are achieved, and green production is achieved.

[0017] 3. The present invention uses low-concentration formic acid and potassium hydroxide to synthesize potassium diformate in one step, which reduces the loss during the evaporation process. Potassium diformate is an unstable dimer that decomposes at high temperatures. The present invention uses reduced pressure distillation at 70°C to reduce the decomposition of potassium diformate and improve the conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD pattern of potassium diformate prepared in Example 1; Figure 2 The formate standard curve diagram prepared in Example 1; Figure 3 is the ion chromatogram obtained in Example 1; Figure 4 An ion chromatogram was obtained for Example 2. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0021] Example 1 This embodiment proposes a method for preparing potassium diformate from low-concentration formic acid, which includes the following steps: at room temperature, add 8.5g of potassium hydroxide solid (purity of 99%) to a reactor, slowly add 157g of formic acid solution (concentration of 9.9%) under stirring, stir and react for 1h, wait for the solution in the reactor to cool to room temperature, and stop stirring. Then pump the solution into the evaporator, use a vacuum pump to extract the negative pressure to -0.1MPa, evaporate under reduced pressure in a 70°C water bath to obtain potassium diformate crystals, and recover 110g of formic acid solution. Dry the potassium diformate crystals at 60°C for 6h to obtain 18.69g of potassium diformate.

[0022] Figure 1 The XRD pattern of potassium diformate obtained in this embodiment is as follows: Figure 1 It can be seen that the XRD peak of the sample corresponds one to one with the standard card peak of potassium diformate, so it can be known that the sample is potassium diformate.

[0023] The formic acid content in the formic acid solution recovered by vacuum distillation in this embodiment was measured to be 1.5%, and the recovery rate of formic acid was 94.7%.

[0024] Draw a formate standard curve: Use a pipette to transfer 20μL, 100μL, 200μL, 500μL, and 1000μL of formic acid standard solution (1000μg / mL) in water into a 10mL volumetric flask, and dilute with water to 10mL. Inject the diluted solution into the ion chromatography injection system for detection, and finally fit the data to obtain the following: Figure 2 Formate standard curve shown.

[0025] The content of formate in the potassium diformate obtained in this example was detected by the following method: 0.49 g of the potassium diformate sample obtained in this example was placed in a 10 mL volumetric flask, diluted to 10 mL with water, 0.1 mL of the dilution was placed in a 100 mL volumetric flask, diluted to 100 mL with water, the diluted solution was transferred to an activated RP column + 0.22 μm filter membrane, 2 mL of the effluent was discarded, 2 mL of the solution was collected and injected into the injection system of the ion chromatograph for detection, and the following results were obtained: Figure 3 According to the ion chromatogram shown in FIG. 1 , the content of formate in the potassium diformate obtained in this embodiment is calculated to be 70% based on the formate standard curve. The purity of the potassium diformate is 97%, and the yield of the potassium diformate is 92.8%.

[0026] Example 2 This embodiment proposes a method for preparing potassium diformate from low-concentration formic acid, which includes the following steps: at room temperature, add 5.1g of potassium hydroxide solid (purity of 99%) to a reactor, slowly add 83.4g of formic acid solution (concentration of 10%) under stirring, stir and react for 30min, wait for the solution in the reactor to cool to room temperature, and stop stirring. Then pump the solution into the evaporator, use a vacuum pump to extract the negative pressure to -0.1MPa, evaporate under reduced pressure in a 70°C water bath to obtain potassium diformate crystals, and recover 50g of formic acid solution. Dry the potassium diformate crystals at 60°C for 6h to obtain 11.02g of potassium diformate.

[0027] The formic acid content in the formic acid solution recovered by vacuum distillation in this embodiment is 1%, and the recovery rate of formic acid is 97%.

[0028] The content of formate in the potassium diformate obtained in this example was detected by the following method: 0.49 g of the potassium diformate sample obtained in this example was placed in a 10 mL volumetric flask, diluted to 10 mL with water, 0.1 mL of the dilution was placed in a 100 mL volumetric flask, diluted to 100 mL with water, the diluted solution was transferred to an activated RP column + 0.22 μm filter membrane, 2 mL of the effluent was discarded, 2 mL of the solution was collected and injected into the injection system of the ion chromatograph for detection, and the following results were obtained: Figure 4As shown in the ion chromatogram, according to the formate standard curve, it is calculated that the potassium diformate obtained in this embodiment contains 69% formate. The calculation shows that the purity of potassium diformate is 98%, and the yield of potassium diformate is 92%.

[0029] Example 3 This embodiment proposes a method for preparing potassium diformate from low-concentration formic acid, which includes the following steps: at room temperature, add 4.23g of potassium hydroxide solid (purity of 99%) to a reactor, slowly add 901.g of formic acid solution (concentration of 8.5%) under stirring, stir and react for 30 minutes, wait for the solution in the reactor to cool to room temperature, and stop stirring. Then pump the solution into the evaporator, use a vacuum pump to extract the negative pressure to -0.1MPa, evaporate under reduced pressure in a 70°C water bath to obtain potassium diformate crystals, and recover 70.7g of formic acid solution. Dry the potassium diformate crystals at 60°C for 6 hours to obtain 9g of potassium diformate.

[0030] The formic acid content in the formic acid solution recovered by vacuum distillation in this embodiment is 1.7%, and the recovery rate of formic acid is 95.6%.

[0031] The content of formate in the potassium diformate obtained in this embodiment is detected, and the specific method is as follows: 0.49 g of the potassium diformate sample obtained in this embodiment is placed in a 10 mL volumetric flask, diluted to 10 mL with water, 0.1 mL of the dilution is placed in a 100 mL volumetric flask, diluted to 100 mL with water, the diluted solution is transferred to an activated RP column + 0.22 μm filter membrane, the 2 mL of effluent that flows out first is discarded, and 2 mL of the solution is collected and injected into the sampling system of the ion chromatograph for detection. According to the formate standard curve, it is calculated that the potassium diformate obtained in this embodiment contains 68% formate. It is calculated that the purity of potassium diformate is 92%, and the yield of potassium diformate is 85%.

[0032] Example 4 This embodiment proposes a method for preparing potassium diformate from low-concentration formic acid, which includes the following steps: at room temperature, add 6.65g of potassium hydroxide solid (purity of 99%) to a reactor, slowly add 173.6g of formic acid solution (concentration of 7%) under stirring, stir and react for 30 minutes, wait for the solution in the reactor to cool to room temperature, and stop stirring. Then pump the solution into the evaporator, use a vacuum pump to extract the negative pressure to -0.1MPa, evaporate under reduced pressure in a 70°C water bath to obtain potassium diformate crystals, and recover 142g of formic acid solution. Dry the potassium diformate crystals at 60°C for 6 hours to obtain 14g of potassium diformate.

[0033] The formic acid content in the formic acid solution recovered by vacuum distillation in this embodiment is 0.8%, and the recovery rate of formic acid is 90.6%.

[0034] The content of formate in the potassium diformate obtained in this embodiment is detected. The specific method is as follows: 0.49 g of the potassium diformate sample obtained in this embodiment is placed in a 10 mL volumetric flask, diluted to 10 mL with water, 0.1 mL of the dilution is placed in a 100 mL volumetric flask, diluted to 100 mL with water, the diluted solution is transferred to an activated RP column + 0.22 μm filter membrane, the 2 mL of effluent that flows out first is discarded, 2 mL of the solution is collected and injected into the sampling system of the ion chromatograph for detection, and the potassium diformate obtained in this embodiment contains 7.6% formate according to the formate standard curve. The calculation shows that the purity of potassium diformate is 95%, and the yield of potassium diformate is 87%.

[0035] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing potassium diformate from low-concentration formic acid, characterized in that: It includes the following steps: Under stirring at room temperature, a formic acid solution with a concentration of less than 10% is added to potassium hydroxide, and stirring is stopped after the temperature of the solution system drops to room temperature; the solution system is evaporated under reduced pressure and dried to obtain potassium diformate.

2. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The concentration of the formic acid solution is 3% to 10%.

3. The method for preparing potassium diformate from low-concentration formic acid according to claim 2, characterized in that: The concentration of the formic acid solution is 5% to 10%.

4. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The molar ratio of formic acid to potassium hydroxide is 2-3:

1.

5. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The stirring time is 1h~3h.

6. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The pressure of the reduced pressure evaporation is -0.05MPa~-0.1MPa.

7. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The temperature of the reduced pressure evaporation is 50-80°C.

8. The method for preparing potassium diformate from low-concentration formic acid according to claim 1, characterized in that: The drying is carried out at 50-80° C. for 5-8 hours.

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