CN119613245A - Preparation method of anhydrous sodium formate - Google Patents

Abstract

The invention relates to the field of sodium formate preparation, in particular to a preparation method of anhydrous sodium formate. The raw materials of the anhydrous sodium formate provided by the invention are formic acid and sodium hydroxide, and the preparation method comprises the following steps of S1 synthetic solution preparation, S2 concentration and crystallization, and S3 dehydration and drying. The preparation method provided by the invention is simple to operate, is environment-friendly, and the sodium formate finished product prepared by the preparation method provided by the invention has high purity, low water content and easy separation from byproducts.

Description

Preparation method of anhydrous sodium formate

Technical Field

The invention relates to the field of sodium formate preparation, in particular to a preparation method of anhydrous sodium formate.

Background

Sodium formate, molecular formula HCOONa, molecular weight 68.01, white granular or crystalline powder, is easily dissolved in water and glycerin. Slightly formic acid smell, and has hygroscopicity. The sodium oxalate and hydrogen gas are decomposed by heating, and then sodium carbonate is produced. Sodium formate is mainly used for producing sodium hydrosulfite, oxalic acid and formic acid. The camouflage acid is used as camouflage acid in the chrome tanning method in the leather industry, is used as a catalyst and a stable synthetic agent, and is a reducing agent in the printing and dyeing industry. The main methods for preparing sodium formate at present are synthesis method and polyol byproduct method.

The synthetic method for producing sodium formate is to use coal as raw material, obtain carbon monoxide gas required by the process through gas making, desulfurizing, decarbonizing and other processes, then react with sodium hydroxide through heating and pressurizing to produce sodium formate solution, and then evaporate, separate and dry to produce solid sodium formate. The process has the following problems that the reaction condition of carbon monoxide and sodium hydroxide is 160-200 ℃ and the pressure is 1.5-2.5 mpa, the corrosiveness of sodium hydroxide at the temperature is greatly changed along with the increase of concentration, the corrosiveness of sodium hydroxide on equipment is greatly increased when the concentration of sodium hydroxide is more than 20%, but the upper limit of the sodium formate content of sodium formate solution produced by sodium hydroxide with the concentration of 20% is only 425g/L, a small amount of carbon dioxide is contained in coal gas, a small amount of impurities such as sodium carbonate, sodium chloride and the like are generated when the coal gas and caustic soda are synthesized, and the impurities are not easy to separate in the subsequent evaporation stage.

And sodium formate contained in an organic phase of a polyol byproduct method promotes the decomposition of polyol when heated in the subsequent polyol separation process, and influences the product quality of the polyol.

Disclosure of Invention

Aiming at the prior art problems, the invention aims to invent a preparation method of anhydrous sodium formate, which aims to solve the problems of more byproducts, difficult separation, high energy consumption and serious pollution of the prior preparation method.

The invention discloses a preparation method of anhydrous sodium formate, which comprises the following steps:

S1, preparing a synthetic solution, namely adding deionized water into an enamel reactor, adding formic acid to obtain a mixed solution, adding sodium hydroxide into the mixed solution while stirring for reaction, and preparing the synthetic solution after the reaction is finished;

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the detection pH value reaches the standard, collecting filtrate, concentrating the collected filtrate under reduced pressure to obtain concentrated synthesis liquid, and cooling and crystallizing the concentrated synthesis liquid to obtain a crystal;

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to dehydrate, controlling the rotation speed and the dehydration time of the centrifugal machine, pumping the dehydrated crystal into a double-cone dryer to dry after the centrifugal dehydration is finished, adjusting the rotation speed, the vacuum degree, the water bath temperature and the drying time of the double-cone dryer, and collecting the dried crystal after the drying is finished, namely anhydrous sodium formate.

Preferably, in the step of preparing the S1 synthetic solution, the mass ratio of the formic acid to the sodium hydroxide is 1 (0.67-0.83).

Preferably, in the step of S2 concentration crystallization, the concentration of the concentrated synthetic solution is 35-40 Bes.

Preferably, in the step of preparing the S1 synthetic solution, the temperature of the mixed solution is controlled to be 60-90 ℃ when sodium hydroxide is added.

Preferably, in the step of S2 concentration and crystallization, the pH value of the synthetic solution reaching the standard is measured to be 6.0-6.5.

Preferably, in the step of S2 concentration and crystallization, the mesh number of the filter used in the filtering process is 150-200 mesh.

Preferably, in the step of S2 concentration and crystallization, the cooling crystallization temperature of the concentrated solution is 18-21 ℃, and the cooling crystallization time is 9-11 h.

Preferably, in the step of S3 dehydration and drying, the rotation speed of a centrifugal machine is 500-800 rpm, and the dehydration time is 20-30min.

Preferably, in the step of S3 dehydration and drying, the rotating speed of the double-cone dryer is 30-50 r/min, and the vacuum degree of the double-cone dryer is-0.08-0.1 mpa.

Preferably, in the step of S3 dehydration and drying, the water bath temperature is 80-100 ℃ in the drying process, and the drying time is 20-24 hours.

Compared with the prior art, the invention has the beneficial effects that:

The invention provides a preparation method of anhydrous sodium formate, which uses formic acid to replace coal as a raw material to react with sodium hydroxide to generate sodium formate solution, can reduce impurities generated in production, improves the purity of sodium formate, and can effectively improve the purity of sodium formate finished products and reduce the water content of sodium formate finished products by controlling parameters such as cooling crystallization, drying temperature, time and the like in the preparation process. The preparation method provided by the invention is simple to operate, green and environment-friendly, and the prepared product is high in purity, low in water content and easy to separate from byproducts.

Drawings

FIG. 1 is a flow chart of anhydrous sodium formate process

Detailed Description

The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.

The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.

Example 1A process for the preparation of anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 500kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.67, controlling the temperature of the mixed solution to be always maintained at 60 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the synthesis liquid is hot after the pH value is detected to be 6.0, collecting filtrate by using a filter with the mesh number of 150 meshes, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid into a crystallization kettle, controlling the temperature of the crystallization kettle to be 15 ℃, starting cooling and crystallizing, and crystallizing for 9 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 500rpm, dehydrating for 20min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 30r/min, the vacuum degree of the double-cone dryer is-0.09 MPa, the water bath temperature is 80 ℃, the drying time is 18h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

Example 2A process for the preparation of anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 525kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.70, controlling the temperature of the mixed solution to be always 65 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the synthesis liquid is hot after the pH value is detected to be 6.1, collecting filtrate by using a filter with the mesh number of 160 meshes, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid into a crystallization kettle, controlling the temperature of the crystallization kettle to be 24 ℃, and starting cooling and crystallizing for 9.5 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 550rpm, dehydrating for 22min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 35r/min, the vacuum degree of the double-cone dryer is-0.08 MPa, the water bath temperature is 85 ℃, the drying time is 20h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

Example 3A process for preparing anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 550kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.73, controlling the temperature of the mixed solution to be always maintained at 70 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the pH value is detected to be 6.2, collecting filtrate by using a filter with 170 meshes, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid to a crystallization kettle, controlling the temperature of the crystallization kettle to be 21 ℃, starting cooling and crystallizing, and crystallizing for 10 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 600rpm, dehydrating for 24min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 40r/min, the vacuum degree of the double-cone dryer is-0.10 MPa, the water bath temperature is 90 ℃, the drying time is 22h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

Example 4A process for the preparation of anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 575kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.76, controlling the temperature of the mixed solution to be always maintained at 75 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the temperature of the synthesis liquid is detected to be 6.3, collecting filtrate by using a filter with the mesh number of 180 meshes, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid to a crystallization kettle, controlling the temperature of the crystallization kettle to be 18 ℃, starting cooling and crystallizing, and crystallizing for 10.5 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 650rpm, dehydrating for 26min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 45r/min, the vacuum degree of the double-cone dryer is-0.11 MPa, the water bath temperature is 95 ℃, the drying time is 24h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

Example 5A process for the preparation of anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 600kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.80, controlling the temperature of the mixed solution to be always maintained at 80 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the synthesis liquid is hot after the pH value is detected to be 6.4, collecting filtrate by using a filter with the mesh number of 190, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid to a crystallization kettle, controlling the temperature of the crystallization kettle to be 26 ℃, starting cooling and crystallizing, and crystallizing for 11 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 700rpm, dehydrating for 28min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 50r/min, the vacuum degree of the double-cone dryer is minus 0.12MPa, the water bath temperature is 100 ℃, the drying time is 27h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

Example 6A process for preparing anhydrous sodium formate comprising the following steps.

And S1, preparing a synthetic solution, namely adding 300L of deionized water into an enamel reactor, adding 750kg of formic acid to obtain a mixed solution, adding 625kg of sodium hydroxide into the mixed solution while stirring for reaction, wherein the mass ratio of the formic acid to the sodium hydroxide is 1:0.83, controlling the temperature of the mixed solution to be always kept at 90 ℃, and preparing the synthetic solution after the reaction is finished.

S2, concentrating and crystallizing, namely filtering the synthesis liquid obtained in the step S1 when the synthesis liquid is hot after the pH value is detected to be 6.5, collecting filtrate by using a filter with the mesh number of 200 meshes, concentrating the collected filtrate under reduced pressure, transferring the concentrated synthesis liquid into a crystallization kettle, controlling the temperature of the crystallization kettle to be 28 ℃, starting cooling and crystallizing, and crystallizing for 11 hours to obtain a crystal.

S3, dehydrating and drying, namely putting the crystal obtained in the step S2 into a centrifugal machine to be dehydrated, controlling the rotation speed of the centrifugal machine to be 800rpm, dehydrating for 30min, vacuumizing the dehydrated crystal into a double-cone dryer to be dried after the centrifugal dehydration is finished, wherein the rotating speed of the double-cone dryer is 50r/min, the vacuum degree of the double-cone dryer is minus 0.13MPa, the water bath temperature is 100 ℃, the drying time is 30h, and collecting the dried crystal after the drying is finished, namely the anhydrous sodium formate.

The anhydrous sodium formate prepared in examples 1 to 6 was tested, and the test data are shown in table 1 below:

TABLE 1

From the above table, it is clear that the anhydrous sodium formate prepared in examples 2 to 5 has high purity, low weight loss on drying, and low contents of chloride, sulfate and phosphate, and meets the regulations.

Comparative example 1 the effect of sodium hydroxide concentration on product purity was investigated.

300L of deionized water was added to the enamel reactor and 750kg of formic acid was added with stirring. Slowly adding different amounts of sodium hydroxide to ensure that the reaction temperature is not more than 90 ℃, and respectively preparing reaction solutions with different solution concentrations. The reaction solution was filtered to clear using a 200 mesh filter. Transferring the filtered reaction liquid into an enamel reaction kettle for decompression concentration, and removing 300L of water until the materials are separated out. And controlling the temperature in the crystallization kettle to 20-23 ℃ and keeping the temperature for 10 hours. The crystallized material is put into a centrifuge for dehydration for 25 minutes. Drying with a double cone dryer at rotation speed of 45r/min, vacuum degree of-0.09 MPa, water bath temperature of 95deg.C, and drying time of 24 hr, and detecting product purity. The experimental results are shown in table 2.

TABLE 2

From the experimental results in the table, the concentration of sodium hydroxide has a significant effect on the product purity of sodium formate within a certain range. At a solution concentration of 37℃Be (experiment No. 2), the product purity reached the highest, 99.9%. When the solution concentration exceeds or falls below 37 DEG Be, the product purity is slightly lowered. This indicates that 37℃Be is the optimal solution concentration and can be used as a reference standard in the production process to obtain anhydrous sodium formate of high purity.

Comparative example 2 the effect of different crystallization temperatures on the purity of the product was investigated.

300L of deionized water was added to the enamel reactor and 750kg of formic acid was added with stirring. 525kg of sodium hydroxide are slowly added to ensure that the reaction temperature does not exceed 90℃and that the solution concentration should be 37℃Be. The reaction solution was filtered to clear using a 200 mesh filter. Transferring the filtered reaction liquid into an enamel reaction kettle for decompression concentration, removing 300L of water until materials are separated out, and carrying out experiments according to different crystallization temperatures. The temperature in the crystallization kettle is controlled to be set value and kept for 10 hours. The crystallized material is put into a centrifuge for dehydration for 25 minutes. The product was dried using a double cone dryer at a rotation speed of 45r/min, a vacuum degree of-0.09 MPa, a water bath temperature of 95℃and a drying time of 24 hours, and the purity of the product was measured, and the experimental results are shown in Table 3.

TABLE 3 Table 3

From the experimental results in the table above, it is clear that the crystallization temperature has a significant effect on the product purity of sodium formate. At a crystallization temperature of 18 ℃ (experiment No. 2), the purity of the product reached the highest, 99.9%, at which point the inorganic salt impurities all meet the specifications. When the crystallization temperature exceeds or falls below 18 ℃, the product purity decreases and the inorganic salt impurities increase. This indicates that 18 ℃ is the optimal crystallization temperature and can be used as a reference standard during production to obtain high purity anhydrous sodium formate.

Comparative example 3 the effect of different drying times on the purity and moisture content of the product was investigated:

300L of deionized water was added to the enamel reactor and 750kg of formic acid was added with stirring. 525kg of sodium hydroxide was slowly added to ensure that the reaction temperature did not exceed 90℃and that the solution concentration was 343g/L. The reaction solution was filtered to clear using a 200 mesh filter. Transferring the filtered reaction liquid into a 1500L enamel reaction kettle for reduced pressure concentration, and removing 300L of water until the materials are separated out. The temperature in the crystallization kettle is controlled to 18 ℃ and maintained for 10 hours. The crystallized material is put into a centrifuge for dehydration for 25 minutes. Drying with a double cone dryer at rotation speed of 45r/min, vacuum degree of-0.09 Mpa, and water bath temperature of 95deg.C. Different drying times were set for the experiments, and the purity of the products was measured, and the experimental results are shown in table 4.

TABLE 4 Table 4

From the experimental results, it can be seen that the drying time has a significant effect on the product purity and water content of sodium formate. At 22 hours and 24 hours of drying (experiment No. 3 and 4), the product purity reached the highest, 99.9%, and the loss on drying was 0.21% and 0.18%, respectively. When the drying time is less than 22 hours or more than 24 hours, the purity of the product is slightly lowered. In the comprehensive consideration of product quality and energy consumption, 22-24 hours is the optimal drying time, and the optimal drying time can be used as a reference standard in the production process to obtain anhydrous sodium formate with high purity and low water content.

In conclusion, the method adopts formic acid to replace coal as a raw material, reduces impurities in the production process, and effectively improves the purity of sodium formate. The purity and the yield of the sodium formate are improved by strictly controlling the reaction conditions in the preparation process. The optimal combination is found out by adjusting the technological parameters such as pH value, reaction temperature and the like, so that the highest yield and purity are realized. The filtering process and the dehydration process are strictly controlled, so that the impurities are effectively removed. The production process is simplified, the energy consumption is low, the environment-friendly requirement is met, and the operation is safe. Through the optimization, the purity and the production efficiency of the anhydrous sodium formate are obviously improved, and the aims of environmental protection and energy saving are fulfilled. The purity of the produced anhydrous sodium formate is up to 99.9%, and the anhydrous sodium formate can meet HG/T5390-2018 (chemical industry standard of the people's republic of China), ACS (American society of chemistry) and EP (European pharmacopoeia) reagent standards.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. A method for preparing anhydrous sodium formate, characterized in that it comprises the following steps: S1 Preparation of synthetic liquid: Deionized water is added to an enamel reactor, and then formic acid is added to obtain a mixed liquid, and then sodium hydroxide is added to the mixed liquid while stirring to react, and after the reaction is completed, a synthetic liquid is obtained; S2 Concentration and crystallization: After the pH value of the synthetic liquid obtained in step S1 is tested to be up to the standard, the synthetic liquid is filtered while hot, the filtrate is collected, the collected filtrate is concentrated under reduced pressure to obtain a concentrated synthetic liquid, and the concentrated synthetic liquid is cooled and crystallized to obtain a crystal; S3 dehydration and drying: the crystals obtained in step S2 are placed in a centrifuge for dehydration, the speed of the centrifuge and the dehydration time are controlled, and then after the centrifugal dehydration is completed, the dehydrated crystals are pumped into a double cone dryer for drying, and the speed, vacuum degree, water bath temperature and drying time of the double cone dryer are adjusted. After the drying is completed, the dried crystals are collected, which are anhydrous sodium formate. 2. The method for preparing anhydrous sodium formate according to claim 1, characterized in that, in the step of preparing the S1 synthetic liquid, the mass ratio of formic acid to sodium hydroxide is 1:(0.67-0.83). 3. The method for preparing anhydrous sodium formate according to claim 1, characterized in that in the S2 concentration and crystallization step, the concentration of the concentrated synthetic solution is 35-40° Bé. 4. The method for preparing anhydrous sodium formate according to claim 1, characterized in that, in the step of preparing the S1 synthetic solution, when adding sodium hydroxide, the temperature of the mixed solution is controlled to be 60-90°C. 5. The method for preparing anhydrous sodium formate according to claim 1, characterized in that in the S2 concentration and crystallization step, the pH value of the synthetic liquid measured to meet the standard is 6.0-6.5. 6. The method for preparing anhydrous sodium formate according to claim 1, characterized in that, in the S2 concentration and crystallization step, the mesh number of the filter used in the filtration process is 150 to 200 meshes. 7. The method for preparing anhydrous sodium formate according to claim 1, characterized in that, in the S2 concentration and crystallization step, the cooling crystallization temperature of the concentrated solution is 18-21° C.; and the cooling crystallization time is 9-11 h. 8. The method for preparing anhydrous sodium formate according to claim 1, characterized in that, in the dehydration and drying step S3, the centrifuge speed is 500-800 rpm; and the dehydration time is 20-30 min. 9. The method for preparing anhydrous sodium formate according to claim 1, characterized in that in the dehydration and drying step S3, the rotation speed of the double cone dryer is 30 to 50 r/min; and the vacuum degree of the double cone dryer is -0.08 to 0.1 MPa. 10. The method for preparing anhydrous sodium formate according to claim 1, characterized in that in the dehydration and drying step S3, the water bath temperature during the drying process is 80-100°C; and the drying time is 20-24h.