KR100396376B1 - A method of extraction of trihydric alcohol - Google Patents

Abstract

The present invention relates to a method for extracting trihydric alcohol, and more particularly, to a method for extracting trihydric alcohol from a product of a trihydric alcohol production process, wherein the alcohol having 4 to 8 carbon atoms, RO-R ' It relates to an extraction method of a trihydric alcohol, characterized in that the trihydric alcohol is extracted using ethers (wherein R and R 'are alkyl groups having 1 to 4 carbon atoms) and water.

According to the extraction method of the present invention, while maximizing the extraction efficiency of the trihydric alcohol, it is possible to completely remove the formate produced as a by-product in the manufacturing process.

Description

Extraction method of trihydric alcohol {A METHOD OF EXTRACTION OF TRIHYDRIC ALCOHOL}

The present invention relates to a method for extracting trihydric alcohol. More specifically, the present invention is a process for preparing a trihydric alcohol by using a mixed solvent of alcohols having 4 to 8 carbon atoms and ethers having ROR 'structural formula wherein R and R' are alkyl groups having 1 to 4 carbon atoms. A method of extracting all the trihydric alcohols produced at the same time by completely separating the by-product sodium formate from the product of.

In the production process of trihydric alcohol, it is common for the byproduct sodium formate to be produced together in the same molar ratio as the trihydric alcohol. Therefore, an extraction process using an organic solvent is used to separate the trihydric alcohol from sodium formate. However, according to the conventional extraction process, since most of the extraction solvents used as well as the trihydric alcohol have a certain degree of solubility in water, there is a problem that the formic acid is dissolved together with the water in the extraction solvent during extraction. This sodium formate decomposes or discolors the trihydric alcohol at high temperatures when distilling the extracted solvent or trihydric alcohol, thereby lowering the quality of the product or lowering the productivity. Therefore, a process for removing sodium formate extracted with trihydric alcohol is required. The following patents have been studied to remove formate.

US 2,468,718 discloses a method for separating trimethylolpropane in solution by precipitating formate with acetone after reaction. However, this method has a disadvantage in that a large amount of trimethylolpropane is lost upon precipitation of formate.

In US Pat. No. 816,208, trimethylolpropane was extracted by using 3.5 pounds of ethyl acetate for each pound of solution as an extraction solvent, and 0.18 parts of water per 100 parts of the raw material injected to remove sodium formate was injected into the top of the extractor. As a result, 0.15 parts of sodium formate are extracted together per 100 parts of trimethylolpropane and it is described that some ethyl acetate and trimethylolpropane are produced.

In US Pat. No. 816,209, only 0.1 part of sodium formate was extracted per 100 parts of trimethylolpropane by extracting trimethylolpropane in a continuous aqueous solution in an extractor using ethyl acetate as an extractant as a discontinuous phase. However, this patent does not mention trimethylolpropane content in the extraction residue.

Both US Pat. Nos. 816,208 and 816,209 do not completely remove sodium formate, even though a great amount of extraction solvent and excellent water are used to remove formate, which causes some discoloration and degeneration during distillation.

In US Pat. No. 3,956,406, 14.1% trivalent alcohol is mixed with a raw material containing 4.8% sodium formate and 11.1% sodium bicarbonate, and xylene, which is 1.48 times as raw material, is injected into the extractor. Isobutanol corresponding to 1.46 times and 0.9 parts of water per 100 parts of the raw material were extracted. 99% of trimethylolpropane was extracted and 1.35 parts of sodium formate were extracted per 100 parts of trimethylolpropane. In this case, the removal of sodium formate is insufficient, and since the concentration of trimethylolpropane in the raw material is low, a very large amount of extraction solvent is required to extract it, which is an unproductive process. Because the process requires 294 kg of solvent per hour to extract 13.9 kg of trimethylolpropane per hour, but can be separated with only 84 kg of solvent per hour if the raw material is 3.5 times concentrated to achieve the same effect. Because.

In US Pat. No. 5,603,835, the product trimethylolpropane solution has 2.5 times the color (60% trihydric alcohol) when the color of the trimethylolpropane solution has a color of 5-10 Gardner unit or 100-300 Apa unit by impurities such as sodium formate. Using methyl tertiary butyl ether as a solvent removes impurities of 0.7 Gardner unit or 30 Apa unit to obtain trimethylolpropane which is not discolored. It is reported that 10% of trimethylolpropane remains in the extraction residue and is recovered, but in this case, a separate apparatus for recovering the solvent used for removing impurities of the product trimethylolpropane is required.

As described above, various methods have been used to remove sodium formate and some effects have been observed. However, if the sodium formate is extracted by injecting water, the trihydric alcohol also has high solubility in water. The solvents that prevent the extraction of formic acid salts, such as xylene and toluene, also reduce the extraction of trihydric alcohols. The result was unproductive results.

Therefore, there is a demand for the selection of a solvent for promoting the extraction of trihydric alcohol and the development of an effective extraction method while suppressing the extraction of sodium formate.

The present invention has been made to solve the above problems, the present inventors maximize the extraction efficiency of trihydric alcohol by using a mixed solvent of a specific alcohol and ether as an extraction solvent and at the same time completely remove the formate as a by-product of the manufacturing process It has been found that the present invention can be completed.

Accordingly, an object of the present invention is to provide a method for extracting trihydric alcohol, which is capable of completely removing all by-products of sodium formate, which are by-products, while simultaneously extracting all trihydric alcohols produced from the product in the trihydric alcohol production process.

In order to achieve the above object, the present invention, in the method for extracting the trihydric alcohol from the product of the trihydric alcohol production process comprising a trihydric alcohol and formate, a) 4 to 8 carbon atoms per 1 weight of the product Alcohols 1 to 5 weight ratio; b) 1 to 3 ethers having a structural formula of RO-R '(wherein R and R' is an alkyl group having 1 to 4 carbon atoms); And c) extracting trihydric alcohol using a mixed solvent comprising 0.01 to 0.6 weight ratio of water.

The trihydric alcohol is preferably trimethylolpropane.

Hereinafter, the present invention will be described in detail.

The product of the trihydric alcohol production process used as a raw material in the present invention includes trihydric alcohol and formate. The concentration of the trihydric alcohol in the raw material is preferably 10 to 50%, more preferably 35 to 45%.

The present invention uses an alcohol having 4 to 8 carbon atoms, an ether having a structure of RO-R '(wherein R and R' is an alkyl group having 1 to 4 carbon atoms) and water to extract the trihydric alcohol. It features.

The alcohol having 4 to 8 carbon atoms functions to extract trivalent alcohol. Since the alcohol having a low carbon number includes a large amount of water at the time of extraction, alcohols having 8 carbon atoms having low solubility in water are preferable. 2-ethylhexanol, normal octanol, etc. are mentioned as an example of the said C8 alcohol. Moreover, it is preferable that the ratio (weight ratio) of the said alcohol with respect to the product of the trihydric alcohol manufacturing process which is an extraction raw material is 1: 1-1: 5. In addition, the alcohols are preferably injected into the bottom of the extractor so that the trihydric alcohol in the raw material can be extracted while going up by the density difference.

The water serves to remove sodium formate, which is a by-product of the trihydric alcohol production process, and is preferably injected into the extractor. It is preferable that the ratio (weight ratio) of the said water with respect to an extraction raw material is 1: 0.01-1: 0.6.

The ether of the R-O-R 'structure (R and R' is an alkyl group having 1 to 4 carbon atoms) functions to prevent the loss of the trihydric alcohol due to the injection of water. The ether is preferably injected in the middle of the extractor. In addition, it is preferable that the ratio (weight ratio) of the said ether with respect to an extraction raw material is 1: 1-1: 3. Methyl tertiary butyl ether, butyl ether, etc. are mentioned as an example of the said ether.

The extractor used in the extraction method of the present invention may use an extractor that is commonly used as a multi-stage extractor. The alcohol having 4 to 8 carbon atoms is injected to the bottom of the extractor, the product of the trihydric alcohol manufacturing process is injected into the upper portion of the 4 to 8 carbon atoms injection stage, the ether is injected into the upper portion of the product injection stage, The water is preferably injected at the top.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, these examples are only for illustrating the present invention, but the present invention is not limited thereto.

Example 1

Extraction of trimethylolpropane was performed using a 7 liter 50 stage multistage countercurrent extractor. The trimethylolpropane aqueous solution raw material produced from the trimethylolpropane manufacturing process was composed of 40% by weight of trimethylolpropane, 20% by weight of sodium formate and 40% by weight of water, and the raw material was injected into the 35-stage position from the bottom of the multistage countercurrent extractor. I was. 2-ethylhexanol was injected into the bottom stage as a first extractant for the extraction of trimethylolpropane, and methyl tertiary butyl ether was injected into the 45 stage, and 48 stages were removed for complete removal of sodium formate. Water was injected at the location. The weight ratio of 2-ethylhexanol and methyl tertiary butyl ether to the raw material injected into the 35 stages was 1: 3: 2. When the weight ratio of water to the raw material reached a steady state at 1: 0.2, the concentrations of trimethylolpropane and sodium formate in the organic solvent coming out of the extractor were measured, respectively, and the concentration of trimethylolpropane in the aqueous solution coming out of the extractor was measured. The concentration of sodium formate in the extract phase from the top of the extractor was 0.03 parts by weight per 100 parts by weight of trimethylolpropane, and less than 1 part by weight of trimethylolpropane in 100 parts by weight of the extraction residue coming out from the bottom. When the extract was distilled in a process for recovering trimethylolpropane which is the next process, discoloration and degeneration did not occur at all.

Example 2

Trimethylolpropane was obtained in the same manner as in Example 1, except that the weight ratio of 2-ethylhexanol and methyl tertiary butyl ether to the raw material was 1: 3.5: 3 and the weight ratio of water to the raw material was 1: 0.15. Was extracted. The concentration of sodium formate in the extraction phase coming out of the top of the extractor was 0.06 parts by weight in 100 parts by weight of trimethylolpropane, and less than 2 parts by weight of trimethylolpropane in 100 parts by weight of the extraction residue coming out from the bottom.

Example 3

Trimethylolpropane was obtained in the same manner as in Example 1, except that the weight ratio of 2-ethylhexanol and methyl tertiary butyl ether to the raw material was 1: 2.5: 1 and the weight ratio of water to the raw material was 1: 0.5. Was extracted. The concentration of sodium formate in the extraction phase coming out of the top of the extractor was 0.03 parts by weight in 100 parts by weight of trimethylolpropane, and less than 7 parts by weight of trimethylolpropane in 100 parts by weight of the extraction residue coming out from the bottom. When the extract was distilled in a process for recovering trimethylolpropane which is the next process, discoloration and degeneration did not occur at all.

Example 4

Normal octanol is used instead of 2-ethylhexanol, except that the weight ratio of normal octanol and methyl tertiary butyl ether to the raw material is 1: 3.5: 1.5 and the weight ratio of water to the raw material is 1: 0.4. , Trimethylolpropane was extracted in the same manner as in Example 1. The concentration of sodium formate in the extraction phase coming out of the top of the extractor was 0.08 parts by weight in 100 parts by weight of trimethylolpropane, and less than 3 parts by weight of trimethylolpropane in 100 parts by weight of the extraction residue coming out from the bottom. When the extract was distilled in a process for recovering trimethylolpropane which is the next process, discoloration and degeneration did not occur at all.

Comparative Example 1

The extraction was carried out in the same manner as in Example 1, but trimethylolpropane was extracted using only 2-ethylhexanol without methyl tertiary butyl ether as a solvent. As a result, 4.2 parts by weight of sodium formate was extracted with respect to 100 parts by weight of trimethylolpropane, which caused discoloration and degeneration during distillation for trimethylolpropane recovery of the extract.

Comparative Example 2

Extraction was carried out in the same manner as in Comparative Example 1, but 8 parts by weight of water was injected into the top of the extraction tower with respect to 100 parts by weight of the raw material to remove sodium formate. As a result, the extraction rate of trimethylolpropane decreased by 10% while 0.1 part by weight of sodium formate was extracted per 100 parts by weight of trimethylolpropane.

Comparative Example 3

Extraction was carried out in the same manner as in Example 1, except that methyl tert-butyl ether and 2-ethylhexanol were used as a solvent, and trimethylolpropane was extracted without using water. As a result, 0.3 parts by weight of sodium formate was extracted with respect to 100 parts by weight of trimethylolpropane, which caused discoloration and denaturation during distillation for recovery of trimethylolpropane.

As described above, according to the method of the present invention, since the complete separation of the trihydric alcohol and sodium formate in the product of the trihydric alcohol manufacturing process occurs, it is possible to improve the productivity of the trihydric alcohol and at the same time obtain a high-purity product. .

Claims (11)

(correction) A method for extracting a trihydric alcohol from a product of a trihydric alcohol production process comprising a trihydric alcohol and a formate, based on 1 weight of the product a) 1 to 5 weight ratios of alcohol having 4 to 8 carbon atoms; b) 1 to 3 weight ratios of ethers having a structure of R-O-R ', wherein R and R' are alkyl groups having 1 to 4 carbon atoms; And c) 0.01 to 0.6 weight ratio of water Extracting trihydric alcohol using a mixed solvent comprising a. The method for extracting trihydric alcohol according to claim 1, wherein the trihydric alcohol is trimethylolpropane. (correction) The method of claim 1, wherein the trihydric alcohol extraction method uses a multi-stage extractor, wherein the C4-8 alcohols are injected to the bottom of the extractor, and the product is injected above the C4-8 alcohol injection stage. Wherein the ether is injected above the product injection stage and the water is injected at the top. The method for extracting trihydric alcohol according to claim 1 or 2, wherein the concentration of the trihydric alcohol in the product of the trihydric alcohol production process is 10 to 50%. The method of extracting trihydric alcohol according to claim 3, wherein the concentration of the trihydric alcohol in the product of the trihydric alcohol production process is 35 to 45%. (delete) (delete) (delete) The method for extracting trihydric alcohol according to claim 1 or 2, wherein the C4-8 alcohol is C8 alcohol. The method for extracting trihydric alcohol according to claim 1 or 2, wherein the C4-8 alcohol is selected from 2-ethylhexanol and normal octanol. The method for extracting trihydric alcohol according to claim 1 or 2, wherein the ether is selected from methyl tertiary butyl ether and butyl ether.