Separation method of sodium formate and pentaerythritol based on mixed solvents
By utilizing a separation method based on mixed solvents and taking advantage of solubility differences and temperature control, the efficient separation of sodium formate, pentaerythritol, and dipentaerythritol was achieved. This method solves the problems of high equipment investment, complex operation, and serious environmental pollution in existing technologies, and enables low-cost industrial production of high-purity products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 淮北矿业绿色化工新材料研究院有限公司
- Filing Date
- 2026-05-08
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies for separating sodium formate, pentaerythritol, and dipentaerythritol suffer from problems such as high equipment investment, high operating costs, low separation efficiency, and serious environmental pollution. In particular, chromatographic methods require large equipment investments, extraction methods use large amounts of extractant and are difficult to recover, and crystallization methods have unsatisfactory separation effects.
A separation method based on mixed solvents is adopted, which utilizes the difference in solubility of sodium formate, pentaerythritol and dipentaerythritol in ethanol-water mixed solvents with different ratios. By controlling the solvent ratio and temperature, the three substances are separated sequentially, including steps such as dissolution, filtration and vacuum distillation using ethanol-water mixed solvents with different ratios.
It achieves efficient separation of three substances, with a product purity of over 98%, reducing production costs, minimizing environmental pollution, simplifying the operation process, and facilitating large-scale industrial production.
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical separation technology, specifically a separation method for sodium formate and pentaerythritol based on a mixed solvent. Background Technology
[0002] In the industrial production of pentaerythritol, formaldehyde and acetaldehyde are typically used as raw materials. They undergo a condensation reaction under the action of an alkaline catalyst (such as sodium hydroxide) to produce pentaerythritol, along with sodium formate as a byproduct. Furthermore, excessive condensation of formaldehyde in the reaction system can generate polymeric impurities such as dipentaerythritol, resulting in a mixed system containing sodium formate, pentaerythritol, and dipentaerythritol.
[0003] Currently, the main methods for separating sodium formate, pentaerythritol, and dipentaerythritol include crystallization, chromatography, and extraction. Chromatography offers high separation efficiency, but requires significant equipment investment and incurs high operating costs, making large-scale industrial production difficult. Extraction requires large amounts of extractant, and its recovery is challenging, potentially causing environmental pollution. Traditional crystallization methods often use a single solvent, resulting in unsatisfactory separation effects and low product purity and yield. Summary of the Invention
[0004] The purpose of this invention is to provide a method for separating sodium formate and pentaerythritol based on a mixed solvent. Utilizing the differences in solubility of sodium formate, pentaerythritol, and dipentaerythritol in ethanol-water mixed solvents of varying proportions, the method achieves sequential separation of the three substances by adjusting parameters such as solvent ratio and temperature. This method boasts high separation efficiency and product purity exceeding 98%. The ethanol-water mixed solvent is widely available, low in cost, and can be recycled through distillation and other methods, reducing production costs and environmental pollution. Furthermore, this invention is simple to operate, requiring no complex equipment or procedures, and is easily scalable for large-scale industrial production, thus addressing the problems mentioned in the background section.
[0005] To achieve the above objectives, the present invention provides the following technical solution: Methods for separating sodium formate and pentaerythritol based on mixed solvents include: Step 1: Add the crude product containing sodium formate, pentaerythritol and dipentaerythritol to a beaker, add ethanol-water mixed solvent A to dissolve it, wherein the volume ratio of ethanol in ethanol-water mixed solvent A is 60%-80%, stir at 10-15℃ for 10-60 min, and filter to obtain crystals a containing pentaerythritol and dipentaerythritol and filtrate a containing sodium formate; Step 2: Add the crystals a obtained in Step 1 to the reactor, and add ethanol-water mixed solvent B at the same time. The volume ratio of ethanol in ethanol-water mixed solvent B is 20%-40%. Stir at 40-60℃ for 10-60 minutes, and filter to obtain crystals b containing pentaerythritol and filtrate b containing pentaerythritol. Step 3: Distill the filtrate a obtained in Step 1 under reduced pressure to remove part of the ethanol-water solution, reducing the volume of filtrate a to 60%-90% of its original volume. Then, cool it to 5-10℃, let it stand for 3-5 hours, and filter to obtain sodium formate crystals. Step 4: Distill the filtrate b obtained in Step 2 under reduced pressure to remove part of the ethanol-water solution, reducing the volume of filtrate b to 30%-50% of its original volume. Then, cool it to 5-10℃, let it stand for 3-5 hours, and filter to obtain pentaerythritol crystals.
[0006] As a further aspect of the present invention: the mass ratio of the crude product in step one to the ethanol-water mixed solvent A is 1:(2-15).
[0007] As a further embodiment of the present invention: the mass ratio of crystal a to ethanol-water mixed solvent B in step two is 1:(1-10).
[0008] As a further embodiment of the present invention: the pressure of vacuum distillation in step three is 0.05-0.08 MPa, and the temperature is 70-90℃.
[0009] As a further embodiment of the present invention: the crystal b is dipentaerythritol. Sodium formate crystal, pentaerythritol crystal and dipentaerythritol crystal are all washed and dried after filtration. The solvent used for washing is the mixed solvent in the corresponding step. The drying temperature is 80-120℃ and the drying time is 4-6 hours.
[0010] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes the differences in solubility of sodium formate, pentaerythritol, and dipentaerythritol in ethanol-water mixed solvents of varying proportions. By adjusting parameters such as solvent ratio and temperature, the three substances are separated sequentially with high separation efficiency and product purity exceeding 98%. Ethanol-water mixed solvents are widely available and low in cost, and can be recycled through methods such as distillation, reducing production costs and environmental pollution. Furthermore, this invention is simple to operate, requiring no complex equipment or procedures, and is easily scalable for large-scale industrial production. Detailed Implementation
[0011] Example 1
[0012] Step 1: Take 10g of crude product into a beaker, add 100mL of ethanol-water mixed solvent A with a volume ratio of 60% ethanol, the mass ratio of crude product to ethanol-water mixed solvent A is 1:9, stir at 15℃ for 30min, and then filter to obtain crystals a containing pentaerythritol and dipentaerythritol and filtrate a containing sodium formate.
[0013] Step 2: Add crystal a to a beaker, and add a certain amount of ethanol-water mixed solvent B with a volume ratio of 30% ethanol. The mass ratio of crystal a to ethanol-water mixed solvent B is 1:8. After stirring at 50℃ for 30 minutes, filter to obtain crystal b containing pentaerythritol and filtrate b containing pentaerythritol.
[0014] Step 3: Distill filtrate a under reduced pressure at 0.05 MPa and 80°C to reduce the volume of filtrate a to 60%-90% of its original volume. Then cool it to 5°C, let it stand for 5 hours, and filter to obtain sodium formate crystals.
[0015] Step 4: Distill filtrate b under reduced pressure at 0.05 MPa and 80°C to reduce its volume to 30%-50% of its original volume. Then cool it to 5°C, let it stand for 5 hours, and filter to obtain pentaerythritol crystals.
[0016] The obtained sodium formate crystals, pentaerythritol crystals, and dipentaerythritol crystals were added to a drying oven at 110℃ and dried for 5 hours. Their purity was then analyzed. The purity analysis method was as follows: a certain amount of sample was taken, dissolved, diluted, and brought to a fixed volume. The concentration was then determined by chromatography, and the weight of the sample in the product was calculated. The ratio of this calculated weight to the weight of the taken sample was the purity. The purities of the three substances obtained by this method were 96.14%, 98.23%, and 98.1%, respectively.
[0017] Example 2
[0018] Step 1: Take 10g of crude product into a beaker, add 100mL of ethanol-water mixed solvent A with a volume ratio of 70% ethanol, the mass ratio of crude product to ethanol-water mixed solvent A is 1:9, stir at 15℃ for 30min, and then filter to obtain crystals a containing pentaerythritol and dipentaerythritol and filtrate a containing sodium formate.
[0019] Step 2: Add crystal a to a beaker, and add a certain amount of ethanol-water mixed solvent B with a volume ratio of 40% ethanol. The mass ratio of crystal a to ethanol-water mixed solvent B is 1:8. After stirring at 50℃ for 30 minutes, filter to obtain crystal b containing pentaerythritol and filtrate b containing pentaerythritol.
[0020] Step 3: Distill filtrate a under reduced pressure at 0.05 MPa and 80°C to reduce the volume of filtrate a to 60%-90% of its original volume. Then cool it to 5°C, let it stand for 5 hours, and filter to obtain sodium formate crystals.
[0021] Step 4: Filtrate b was subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 80℃, reducing its volume to 30%-50% of its original volume. It was then cooled to 5℃, allowed to stand for 5 hours, and filtered to obtain pentaerythritol crystals. The obtained sodium formate crystals, pentaerythritol crystals, and dipentaerythritol crystals were dried in a drying oven at 110℃ for 5 hours, and their purity was analyzed. The purity analysis method was as follows: a certain amount of sample was taken, dissolved, diluted, and brought to a fixed volume. The concentration was then determined by chromatography, and the weight of the sample in the product was calculated. The ratio of this calculated concentration to the weight of the taken sample was the purity. The purities of the three were 97.34%, 98.46%, and 95.1%, respectively.
[0022] Example 3
[0023] Step 1: Take 10g of crude product into a beaker, add 100mL of ethanol-water mixed solvent A with a volume ratio of 80% ethanol, the mass ratio of crude product to ethanol-water mixed solvent A is 1:9, stir at 15℃ for 30min, and then filter to obtain crystals a containing pentaerythritol and dipentaerythritol and filtrate a containing sodium formate.
[0024] Step 2: Add crystal a to a beaker, and add a certain amount of ethanol-water mixed solvent with a volume ratio of 20% ethanol. The mass ratio of crystal a to mixed solvent B is 1:8. After stirring at 50℃ for 30 minutes, filter to obtain crystal b containing dipentaerythritol and filtrate b containing pentaerythritol.
[0025] Step 3: Distill filtrate a under reduced pressure at 0.05 MPa and 80°C to reduce the volume of filtrate a to 60%-90% of its original volume. Then cool it to 5°C, let it stand for 5 hours, and filter to obtain sodium formate crystals.
[0026] Step 4: Filtrate b is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 80℃ to reduce the volume of filtrate a to 30%-50% of its original volume. The solution is then cooled to 5℃, allowed to stand for 5 hours, and filtered to obtain pentaerythritol crystals. The obtained sodium formate crystals, pentaerythritol crystals, and dipentaerythritol crystals are dried in a drying oven at 110℃ for 5 hours, and their purity is analyzed. The purity analysis method is as follows: a certain amount of sample is taken, dissolved, diluted, and brought to a fixed volume. The concentration is then determined by chromatography, and the weight of the sample in the product is calculated. The ratio of this concentration to the weight of the taken sample is the purity. The purities of the three are 98.56%, 97.13%, and 98.67%, respectively.
[0027] The applicant declares that the present invention illustrates the detailed features of the method for separating sodium formate, pentaerythritol, and dipentaerythritol using an ethanol-water solution through the above embodiments. However, the present invention is not limited to the above detailed embodiments, that is, it does not mean that the present invention must be implemented under the above detailed implementation conditions. Those skilled in the art should understand that any improvements to the implementation conditions of the present invention, equivalent substitutions for the selected implementation methods, additions to other methods, or selection of specific methods, as long as the method for separating sodium formate, pentaerythritol, and dipentaerythritol using an ethanol-water solution falls within the protection and disclosure scope of the present invention.
[0028] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0029] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0030] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method for separating sodium formate and pentaerythritol based on a mixed solvent, characterized in that: include: Step 1: Add the crude product containing sodium formate, pentaerythritol and dipentaerythritol to a beaker, add ethanol-water mixed solvent A to dissolve it, wherein the volume ratio of ethanol in ethanol-water mixed solvent A is 60%-80%, stir at 10-15℃ for 10-60 min, and filter to obtain crystals a containing pentaerythritol and dipentaerythritol and filtrate a containing sodium formate; Step 2: Add the crystals a obtained in Step 1 to the reactor, and add ethanol-water mixed solvent B at the same time. The volume ratio of ethanol in ethanol-water mixed solvent B is 20%-40%. Stir at 40-60℃ for 10-60 minutes, and filter to obtain crystals b containing pentaerythritol and filtrate b containing pentaerythritol. Step 3: Distill the filtrate a obtained in Step 1 under reduced pressure to remove part of the ethanol-water solution, reducing the volume of filtrate a to 60%-90% of its original volume. Then, cool it to 5-10℃, let it stand for 3-5 hours, and filter to obtain sodium formate crystals. Step 4: Distill the filtrate b obtained in Step 2 under reduced pressure to remove part of the ethanol-water solution, reducing the volume of filtrate b to 30%-50% of its original volume. Then, cool it to 5-10℃, let it stand for 3-5 hours, and filter to obtain pentaerythritol crystals.
2. The method for separating sodium formate and pentaerythritol based on a mixed solvent according to claim 1, characterized in that: The mass ratio of the crude product to the ethanol-water mixed solvent A in step one is 1:(2-15).
3. The method for separating sodium formate and pentaerythritol based on a mixed solvent according to claim 2, characterized in that: In step two, the mass ratio of crystal a to the ethanol-water mixed solvent B is 1:(1-10).
4. The method for separating sodium formate and pentaerythritol based on a mixed solvent according to claim 1, characterized in that: The pressure of vacuum distillation in step three is 0.05-0.08 MPa, and the temperature is 70-90℃.
5. The method for separating sodium formate and pentaerythritol based on a mixed solvent according to claim 1, characterized in that: Sodium formate crystals, pentaerythritol crystals, and dipentaerythritol crystals were all washed and dried after filtration. The solvent used for washing was the mixed solvent from the corresponding step. The drying temperature was 80-120℃, and the drying time was 4-6 hours.