阅读说明：本技术 一种三辛基甲基草酸铵的制备方法 (Preparation method of trioctylmethylammonium oxalate ) 是由 刘子帅 罗仙平 汪金良 周贺鹏 于 2020-12-03 设计创作，主要内容包括：本发明提供一种三辛基甲基草酸铵的制备方法,属于萃取剂合成技术领域。该方法首先将三辛基叔胺与异辛醇混合,置于竖式反应器中,持续通入氯甲烷,在100～200℃条件下反应5～10h,然后转移至降膜式液膜蒸馏仪中,在120～150℃和2～8mm(Hg柱)条件下蒸馏,得到三辛基甲基氯化铵；将三辛基甲基氯化铵与湿的氧化银混合,置于反应釜中反应,得到三辛基甲基氢氧化铵；将三辛基甲基氢氧化铵与草酸溶液混合,置于反应釜中反应,得到三辛基甲基草酸铵粗产品,然后用去离子水洗涤,再进行真空干燥,得到三辛基甲基草酸铵产品。本发明合成的三辛基甲基草酸铵具有萃取能力强、产率高和绿色环保的特点。(The invention provides a preparation method of trioctylmethylammonium oxalate, belonging to the technical field of extractant synthesis. Mixing trioctyl tertiary amine and isooctyl alcohol, placing the mixture in a vertical reactor, continuously introducing methyl chloride, reacting for 5-10 hours at the temperature of 100-200 ℃, transferring the mixture to a falling film liquid film distiller, and distilling the mixture at the temperature of 120-150 ℃ and under the condition of 2-8 mm (Hg column) to obtain trioctyl methyl ammonium chloride; mixing trioctylmethylammonium chloride with wet silver oxide, and placing the mixture in a reaction kettle for reaction to obtain trioctylmethylammonium hydroxide; and mixing the trioctyl methyl ammonium hydroxide with the oxalic acid solution, placing the mixture in a reaction kettle for reaction to obtain a crude trioctyl methyl ammonium oxalate product, washing the crude trioctyl methyl ammonium oxalate product with deionized water, and then carrying out vacuum drying to obtain the trioctyl methyl ammonium oxalate product. The trioctylmethylammonium oxalate synthesized by the method has the characteristics of strong extraction capability, high yield and environmental protection.)

1. A preparation method of trioctylmethylammonium oxalate is characterized in that: the method comprises the following steps:

(1) mixing trioctyl tertiary amine and isooctyl alcohol, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 100-300 mL/min, and reacting for 5-10 h at the temperature of 100-200 ℃ to obtain a trioctyl methyl ammonium chloride crude product;

(2) transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ under the condition of 2-8 mmHg column to obtain trioctylmethylammonium chloride;

(3) mixing trioctylmethylammonium chloride with wet silver oxide, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 40 and 80 ℃, cooling the mixture to room temperature, and then splitting phases to obtain trioctylmethylammonium hydroxide;

(4) mixing trioctylmethylammonium hydroxide and oxalic acid, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 30 and 60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctylmethylammonium oxalate product;

(5) washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 1-4, and carrying out phase separation to obtain a dilute trioctyl ammonium methyl oxalate solution;

(6) and (3) carrying out vacuum drying on the trioctyl methyl ammonium oxalate dilute solution for 12-24 h at the temperature of 40-60 ℃ to obtain a trioctyl methyl ammonium oxalate product.

2. The method according to claim 1, wherein: in the step (1), the volume ratio of the trioctyl tertiary amine to the isooctyl alcohol is 1: 1.5-3.

3. The method according to claim 1, wherein: the molar ratio of the trioctylmethylammonium chloride to the wet silver oxide in the step (3) is 1: 1-3.

4. The method according to claim 1, wherein: the molar ratio of the trioctylmethylammonium hydroxide to the oxalic acid in the step (4) is 1: 1-4.

Technical Field

The invention relates to the technical field of extractant synthesis, in particular to a preparation method of trioctylmethylammonium oxalate.

Background

Quaternary aminesSalt is a good extractant, mainly extracting metal ions present in anionic form. The quaternary ammonium salts commonly used are mainly trioctylmethylammonium chloride, followed by trioctylmethylammonium sulfate, trioctylmethylammonium bromide, trioctylmethylammonium nitrate, and the like. The quaternary ammonium salt extractant is usually a mixture based on octyl and has the formula R₃NCH₃Cl(R＝C₈-C₁₀) Its molecular structure determines it has three distinct characteristics: the molecule contains three long carbon chain alkyl groups, so that the oil-soluble polymer has better oil solubility; containing one exchangeable Cl in the molecule^-Can be exchanged with other metal anions; unlike other amine-based extractants, quaternary ammonium salt extractants can be extracted under a wider pH condition. These characteristics make it a very effective extractant. However, this extractant also has the disadvantage that when the anionic group is Cl^-Is exchanged into raffinate which contains a large amount of chloride ions, so that the concentration of the chloride ions in the extracting agent is higher, and wastewater which is difficult to treat and has pollution is formed. Similarly, when trioctylmethylammonium bromide and trioctylmethylammonium nitrate are used as extractants, contaminated Br is also produced^-And NO₃ ^-Ions, thereby generating wastewater which is difficult to treat and has strong pollution. And the trioctylmethylammonium sulfate has weak extraction capacity relative to trioctylmethylammonium chloride and low extraction rate. In addition, the existing preparation method of the trioctylmethylammonium chloride is complex, the organic phase separation is difficult, the added solvent amount is high, and the trioctylmethylammonium chloride can be dissolved in the solvent, so that the yield of the synthesized trioctylmethylammonium chloride is low.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of trioctylmethylammonium oxalate, which is used as an extracting agent and has strong extraction capacity, high yield and environmental protection.

The method comprises the following steps:

(1) mixing trioctyl tertiary amine and isooctyl alcohol, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 100-300 mL/min, and reacting for 5-10 h at the temperature of 100-200 ℃ to obtain a trioctyl methyl ammonium chloride crude product;

(2) transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ under the condition of 2-8 mmHg column to obtain trioctylmethylammonium chloride;

(3) mixing trioctylmethylammonium chloride with wet silver oxide, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 40 and 80 ℃, cooling the mixture to room temperature, and then splitting phases to obtain trioctylmethylammonium hydroxide;

(4) mixing trioctylmethylammonium hydroxide and oxalic acid, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 30 and 60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctylmethylammonium oxalate product;

(5) washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 1-4, and carrying out phase separation to obtain a dilute trioctyl ammonium methyl oxalate solution;

(6) and (3) carrying out vacuum drying on the trioctyl methyl ammonium oxalate dilute solution for 12-24 h at the temperature of 40-60 ℃ to obtain a trioctyl methyl ammonium oxalate product.

Wherein: in the step (1), the volume ratio of the trioctyl tertiary amine to the isooctyl alcohol is 1: 1.5-3.

In the step (3), the molar ratio of the trioctylmethylammonium chloride to the wet silver oxide is 1: 1-3.

In the step (4), the molar ratio of the trioctylmethylammonium hydroxide to the oxalic acid is 1: 1-4.

The technical scheme of the invention has the following beneficial effects:

in the scheme, compared with the traditional quaternary ammonium salt extractant, the anion group of the obtained extractant is oxalate, and when octyl methyl ammonium oxalate is used for extracting metal anions, the oxalate in the extractant is exchanged into raffinate, so that the oxalate concentration of the raffinate is greatly increased. According to the principle of weak acid preparation by strong acid, the oxalic acid radical in the raffinate can be recovered in the form of oxalic acid by adding sulfuric acid and re-evaporating and crystallizing, so that the problem of raffinate pollution is avoided, the oxalic acid can be recovered, and the method is safe, green and environment-friendly. The trioctylmethylammonium oxalate synthesized by the method has the characteristics of strong extraction capacity, high purity and environmental protection.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is given with reference to specific embodiments.

The invention provides a preparation method of trioctylmethylammonium oxalate.

Mixing trioctyl tertiary amine and isooctyl alcohol, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 100-300 mL/min, and reacting at the temperature of 100-200 ℃ for 5-10 h to obtain a trioctyl methyl ammonium chloride crude product;

(2) transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ under the condition of 2-8 mmHg column to obtain trioctylmethylammonium chloride;

(3) mixing trioctylmethylammonium chloride with wet silver oxide, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 40 and 80 ℃, cooling the mixture to room temperature, and then splitting phases to obtain trioctylmethylammonium hydroxide;

(4) mixing trioctylmethylammonium hydroxide and oxalic acid, placing the mixture in a reaction kettle, stirring the mixture for 2 to 6 hours at the temperature of between 30 and 60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctylmethylammonium oxalate product;

(5) washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 1-4, and carrying out phase separation to obtain a dilute trioctyl ammonium methyl oxalate solution;

(6) and (3) carrying out vacuum drying on the trioctyl methyl ammonium oxalate dilute solution for 12-24 h at the temperature of 40-60 ℃ to obtain a trioctyl methyl ammonium oxalate product.

Wherein the volume ratio of the trioctyl tertiary amine to the isooctyl alcohol in the step (1) is 1: 1.5-3.

In the step (3), the molar ratio of the trioctylmethylammonium chloride to the wet silver oxide is 1: 1-3.

In the step (4), the molar ratio of the trioctylmethylammonium hydroxide to the oxalic acid is 1: 1-4.

The yield of the trioctylmethylammonium oxalate synthesized by the method is more than 90%, and the purity is more than 98%. Taking an oxalic acid solution for extracting vanadium (the concentration of vanadium is 1.2g/L, the concentration of oxalate is 120g/L, and the initial pH is 0.8) as an example, under the conditions that the concentrations of the extracting agents are respectively 10%, 20%, 30% and 40%, the comparison ratio of O/A is 1: 2, and the extraction time is 5min, compared with other extracting agents, when the concentration of the extracting agent is 20%, the single-stage vanadium extraction rate obtained by trioctylmethylammonium oxalate is 76%, the using amount of the extracting agent is further increased, and the vanadium extraction rate is slightly increased; the vanadium extraction rates of other quaternary ammonium salt extractants are lower, the vanadium extraction rates of trioctylmethylammonium chloride, trioctylmethylammonium bromide, trioctylmethylammonium nitrate and trioctylmethylammonium sulfate are respectively 52%, 55%, 41% and 40%, the dosage of the extractant is further increased, and the vanadium extraction rates are greatly increased; however, even if the concentration of the extractant reaches 40%, the vanadium extraction rate is lower than that of trioctylmethylammonium oxalate with a concentration of 20%, so that trioctylmethylammonium oxalate has stronger extraction capability.

TABLE 1 vanadium extraction yield for different concentrations of extractant

The following description is given with reference to specific examples.

Example 1

A method for synthesizing trioctylmethylammonium oxalate. The synthesis method of trioctylmethylammonium oxalate described in this example is:

step 1, mixing trioctyl tertiary amine and isooctyl alcohol according to the volume ratio of 1: 1.5-2, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 100-200 mL/min, and reacting for 5-8 h at the temperature of 100-150 ℃ to obtain a crude product of trioctyl methyl ammonium chloride;

step 2, transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ and 2-6 mm (Hg) to obtain trioctylmethylammonium chloride;

step 3, mixing trioctylmethylammonium chloride and wet silver oxide according to the molar ratio of 1: 1-1.5, placing the mixture in a reaction kettle, stirring the mixture for 2-4 hours at the temperature of 40-60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain trioctylmethylammonium hydroxide;

step 4, mixing the trioctyl methyl ammonium hydroxide and oxalic acid according to the molar ratio of 1: 1-2, placing the mixture in a reaction kettle, stirring the mixture for 2-4 hours at the temperature of 30-60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctyl methyl ammonium oxalate product;

and 5, washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 1-2, and carrying out phase splitting to obtain a dilute trioctyl ammonium methyl oxalate solution.

And 6, drying the trioctyl methyl ammonium oxalate dilute solution at 40-60 ℃ for 12-18 h in vacuum to obtain a trioctyl methyl ammonium oxalate product.

Trioctylmethylammonium oxalate obtained in this example: the yield is more than 95.3 percent, and the purity is more than 98.5 percent. Taking the oxalic acid solution for extracting vanadium (the concentration of vanadium is 1.5g/L, the concentration of oxalate is 150g/L, and the initial pH is 0.7) as an example, under the conditions that the concentration of an extracting agent is 25%, the ratio of O/A is 1: 2, and the extraction time is 5min, the single-stage vanadium extraction rate obtained by the trioctylmethylammonium oxalate is 82%, and the effects are better than those achieved by other extracting agents.

Example 2

A method for synthesizing trioctylmethylammonium oxalate. The synthesis method of trioctylmethylammonium oxalate described in this example is:

step 1, mixing trioctyl tertiary amine and isooctyl alcohol according to the volume ratio of 1: 2-2.5, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 150-250 mL/min, and reacting for 6-9 hours at the temperature of 130-180 ℃ to obtain a crude product of trioctyl methyl ammonium chloride;

step 2, transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ and 3-7 mm (Hg) to obtain trioctylmethylammonium chloride;

step 3, mixing trioctylmethylammonium chloride and wet silver oxide according to the molar ratio of 1: 1.5-2.5, placing the mixture in a reaction kettle, stirring for 3-5 hours at the temperature of 50-70 ℃, cooling to room temperature, and then carrying out phase separation to obtain trioctylmethylammonium hydroxide;

step 4, mixing the trioctyl methyl ammonium hydroxide and an oxalic acid solution according to the molar ratio of 1: 2-3, placing the mixture in a reaction kettle, stirring the mixture for 3-5 hours at the temperature of 30-60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctyl methyl ammonium oxalate product;

and 5, washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 2-3, and carrying out phase splitting to obtain a dilute trioctyl ammonium methyl oxalate solution.

And 6, drying the trioctyl ammonium methyl oxalate dilute solution for 15-21 h under the condition of 40-60 ℃ in vacuum to obtain a trioctyl ammonium methyl oxalate product.

Trioctylmethylammonium oxalate obtained in this example: the yield is more than 95.5 percent, and the purity is more than 98.3 percent. Taking an oxalic acid solution for extracting iron (the concentration of iron is 4.2g/L, the concentration of oxalate is 80g/L, and the initial pH is 1.5) as an example, under the conditions that the concentration of an extracting agent is 25%, the ratio of O/A is 1: 2, and the extraction time is 5min, the single-stage iron extraction rate obtained by the trioctylmethylammonium oxalate is 78%, and the effects are better than those achieved by other extracting agents.

Example 3

A method for synthesizing trioctylmethylammonium oxalate. The synthesis method of trioctylmethylammonium oxalate described in this example is:

step 1, mixing trioctyl tertiary amine and isooctyl alcohol according to the volume ratio of 1: 2.5-3, placing the mixture in a vertical reactor, continuously introducing methyl chloride at the speed of 200-300 mL/min, and reacting for 7-10 h at the temperature of 150-200 ℃ to obtain a crude product of trioctyl methyl ammonium chloride;

step 2, transferring the crude product of the trioctylmethylammonium chloride into a falling film liquid film distiller, and distilling at 120-150 ℃ and 4-8 mm (Hg column) to obtain trioctylmethylammonium chloride;

step 3, mixing trioctylmethylammonium chloride and wet silver oxide according to the molar ratio of 1: 2-3, placing the mixture in a reaction kettle, stirring the mixture for 4-6 hours at the temperature of 60-80 ℃, cooling the mixture to room temperature, and then splitting phases to obtain trioctylmethylammonium hydroxide;

step 4, mixing the trioctyl methyl ammonium hydroxide and oxalic acid according to the molar ratio of 1: 3-4, placing the mixture in a reaction kettle, stirring the mixture for 4-6 hours at the temperature of 30-60 ℃, cooling the mixture to room temperature, and then splitting phases to obtain a crude trioctyl methyl ammonium oxalate product;

step 5, washing the crude trioctyl ammonium methyl oxalate product with deionized water for 3-5 times according to the volume ratio of 1: 3-4, and carrying out phase splitting to obtain a dilute trioctyl ammonium methyl oxalate solution;

and 6, drying the trioctyl methyl ammonium oxalate dilute solution for 18-24 hours at 40-60 ℃ in vacuum to obtain a trioctyl methyl ammonium oxalate product.

Trioctylmethylammonium oxalate obtained in this example: the yield was 95.1% and the purity 98.8%. Taking the oxalic acid solution for extracting chromium (the concentration of chromium is 1.5g/L, the concentration of oxalate is 150g/L, and the pH of the solution is 1.2) as an example, under the conditions that the concentration of an extracting agent is 20 percent, the ratio of O/A is 1: 2, and the extraction time is 5min, the single-stage chromium extraction rate obtained by the trioctylmethylammonium oxalate is 80 percent, and the effects are better than those achieved by other extracting agents.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.