WO2017052291A1 - Method for purifying waste organic solvent - Google Patents

Abstract

The present invention pertains to a method for purifying a waste organic solvent which can prevent equipment damage and economic cost increase due to impurities by more efficiently removing impurities in a waste organic solvent. Specifically, the method for purifying a waste organic solvent may comprise: a step of extracting a metal salt using an aqueous solvent at pH 3 or lower, by mixing an aqueous solvent into a waste organic solvent comprising 50 wt% or less of a metal salt; a step of controlling the pH of the mixture to 5 to 9; and a step of removing the aqueous solvent and the metal salt.

Description

 【Specification】

 [Name of invention]

 Method for Purifying Waste Organic Solvents

 Technical Field

Cross Citation with Related Applications

 This application claims the benefit of priority based on Korean Patent Application No. 10-2015-0134721 dated September 23, 2015, and all the contents disclosed in the literature of that Korean patent application are incorporated as part of this specification.

 The present invention relates to a waste organic solvent and a purification method. More specifically, the present invention relates to a method for purifying waste organic solvents that can increase the efficiency of removing impurities contained in waste organic solvents and prevent damage to equipment and increase of economic costs caused by impurities.

 [Technique to become background of invention]

 An organic solvent refers to a carbon compound (hydrocarbon, alcohol, ether, amine, etc.) that dissolves and extracts a target substance but does not react with the target substance, and is used in a variety of industries such as fiber manufacturing, paper product manufacturing, rubber product and plastic product manufacturing. A large amount of waste organic solvent is used in one field, and its quantity and price are gradually increasing.

 Therefore, in order to increase the price competitiveness of the product, it is important to recover the waste organic solvent from the purification of the product. Generally, a distillation process through a distillation column is used to remove impurities in the waste organic solvent.

 However, in the case of waste organic solvents containing impurities such as metal chlorides, the metal chlorides in the waste organic solvent and the water remaining in the distillation column react to generate hydrogen chloride and reaction by-products, causing problems such as corrosion and tray clogging. There was a limit.

 Therefore, before proceeding with the distillation process using a distillation column, a study on how to remove impurities contained in the waste organic solvent is required.

 [Content of invention]

Problem to be solved The present invention is to provide a method for purifying waste organic solvents that can increase the removal efficiency of impurities contained in the waste organic solvent, thereby preventing equipment damage and increase in economic cost caused by impurities.

 [Measures of problem]

 In the present specification, by mixing an aqueous solvent in a waste organic solvent containing less than 50% by weight metal salt, extracting the metal salt with an aqueous solvent at pH 3 or less; Adjusting the pH of the mixture to 5-9; And removing the aqueous solvent and the metal salt.

 Hereinafter, a method for purifying waste organic solvent according to a specific embodiment of the present invention will be described in more detail. According to an embodiment of the present invention, the method comprises: mixing an aqueous solvent with a waste organic solvent containing 50 wt% or less of a metal salt, and extracting the metal salt into an aqueous solvent at ρΠ 3 or less; Adjusting the pH of the mixture to 5-9; And removing the aqueous solvent and the metal salt. A method for purifying waste organic solvents may be provided.

 The inventors of the present invention use the above-described method for purifying a waste organic solvent, and as the metal salt, which is an impurity contained in the waste organic solvent, is extracted with an aqueous solvent under an acidic condition of pH 3 or less, the content of impurities in the waste organic solvent is increased. Experiments confirmed that it can reduce and completed the invention.

 In particular, the metal salt can be obtained through the reaction with the aqueous solvent, the acidic material can be obtained as a reaction product, it is possible to satisfy the acidic conditions of pH 3 or less by the addition of an aqueous solvent without the addition of additional acidic material.

 Also. Since the metal salt may have a higher solubility in an aqueous solvent than an organic solvent in an acidic condition of pH 3 or less, the extraction may be performed in which the additive metal salt moves from the organic solvent to the aqueous solvent through spontaneous equilibrium shifting.

And, by neutralizing the aqueous solvent by mixing a basic material in the aqueous solvent, not only can prevent corrosion of the equipment according to the strong acidity, but also precipitates a metal salt, which is an impurity transferred to the aqueous solvent, the subsequent separation and My In the process, impurities can be removed more smoothly.

 Particularly, when the aqueous solvent and the basic material are mixed and added together at the same time, phase separation between the aqueous solvent and the organic solvent is difficult to proceed sufficiently, and impurities such as metal salts in the organic solvent precipitated by reacting with the basic material. There was a problem that existed. On the other hand, in the above embodiment, first, only the aqueous solvent is added to proceed with phase separation and extraction for a sufficient time, the impurities are transferred to the aqueous solvent, and then a basic substance is added thereto, whereby the content of the impurities contained in the waste organic solvent is increased. Can be reduced more effectively.

 Hereinafter, the method for purifying the waste organic solvent of the embodiment will be described in more detail. The method for purifying the waste organic solvent may include mixing the aqueous solvent with the waste organic solvent containing the metal salt in an amount of 50 wt% or less, and extracting the metal salt into the aqueous solvent at pH 3 or less.

 Examples of the reaction product from which the waste organic solvent is obtained are not limited thereto, but may include, for example, an organic solvent used in a catalyst synthesis reaction, specifically, a catalyst synthesis reaction for producing polyolefins, a catalyst synthesis reaction for reductive amination reaction, and the like.

 The waste organic solvent may include a impurities such as metal salts in an amount of 50 wt% or less, 10 wt% to 40 wt%, or 5 wt% to 20 wt%, based on the total weight of the waste organic solvent. In addition, the remaining amount may further include an organic solvent. That is, the waste organic solvent means a material in which impurities such as metal salts are mixed in the organic solvent, and the organic solvent used herein may mean an organic solvent included in the waste organic solvent.

In particular, the extraction may proceed at a pH of 3 or less, or 0.01 to 3. The extraction means a phenomenon in which the metal salt contained in the waste organic solvent moves from an organic solvent to an aqueous solvent through spontaneous equilibrium movement, and the pH of the semi-ungular solution in which the waste organic solvent and the aqueous solvent are mixed in the extraction step is less than 3 days. Can be. The aqueous solvent may be mixed with the waste organic solvent and form an acidic substance as a reaction product by reacting with the metal salt contained in the waste organic solvent. Therefore, the extraction step by the acidic substance of the reaction by-product may be carried out at a strong acidity of pH 3 or less.

 As the extraction step proceeds to pH 3 or less, the solubility of the metal salt in an organic solvent may be smaller than the solubility of the metal salt in an aqueous solvent. Accordingly, the metal salt can be moved from the organic solvent to the aqueous solvent.

 More specifically, the distribution coefficient of the metal salt obtained by Equation 1 may be 1 to 2000, or 500 to 2000, or 700 to 1500, or 800 to 1200.

 [Equation 1]

 Partition coefficient = solubility of metal salts in aqueous solvents / solubility of metal salts in organic solvents

 When the distribution coefficient of the metal salt obtained by Equation 1 is too small, as the ratio of the metal salt remaining in the organic solvent in the extraction step increases, the purification efficiency of the method for purifying the waste organic solvent may decrease.

 On the other hand, if the extraction step is a pH of more than 3, the metal salt does not move to the aqueous solvent, remaining in the waste organic solvent may reduce the efficiency of the process or economic efficiency in the purification process.

 In the step of extracting the metal salt with an aqueous solvent at pH 3 or less by mixing an aqueous solvent with a waste organic solvent containing 50% by weight or less of the metal salt, a pH adjusting material is added to the waste organic solvent containing 50% by weight or less of the metal salt. It may further comprise the step of adding.

 The pH adjusting material is a material that can be added to the waste organic solvent to affect the pH of the entire semi-aqueous solution, and may include an acidic substance or a basic substance which is widely used in the prior art, and examples of the acidic substance or the basic substance Is not largely limited.

 The density of the aqueous solvent may be greater than the density of the organic solvent. Accordingly, the aqueous solvent may be introduced into the upper portion of the flask containing the waste organic solvent, and may react with the metal salt included in the waste organic solvent.

The weight ratio of the aqueous solvent to the organic solvent is 0.1 to 10, or 0.5 To 5 may be. The weight ratio of the aqueous solvent to the organic solvent means a value obtained by dividing the weight of the aqueous solvent by the weight of the organic solvent, and when the weight ratio of the aqueous solvent to the organic solvent is excessively reduced to less than 0.1, Extraction with an aqueous solvent may be difficult to proceed, and neutralization heat may be difficult to remove. In addition, when the weight ratio of the aqueous solvent to the organic solvent is excessively increased to more than 10, the utility cost and extraction efficiency of the extraction and neutralization process can be greatly reduced.

 The metal salt may comprise a Group IVb or Group Vb metal. Examples of the IVb or group Vb metals are not particularly limited, but, for example, titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), hafnium (Hf), tantalum (Ta), and the like. Can be mentioned.

In addition, the metal salt may include a chloride or hydroxide of the metal. Specifically, the chloride of the metal may react with water, which is the aqueous solvent, to generate hydroxide and hydrochloric acid of the metal. The metal salt may be extracted with the aqueous solvent in the form of the chloride, the hydroxide of the metal, or a mixture thereof. have. Specific examples of the chloride of the metal may include TiCl ₄ , and specific examples of the hydroxide of the metal may include Ti (0H) ₄ .

 The aqueous solvent may comprise water (0). The water has a neutral pH of 7, but as described above, when the water reacts with the metal salt, hydrochloric acid (HC1) is obtained as a reaction product, and the hydrochloric acid is dissolved in water so that the pH is 3 Can be reduced.

 The organic solvent may include at least one selected from the group consisting of aliphatic hydrocarbons having 1 to 20 carbon atoms, aromatic hydrocarbons having 6 to 20 carbon atoms, aliphatic alcohols having 1 to 20 carbon atoms, aromatic alcohols having 6 to 20 carbon atoms, ketones and aldehydes. Can be. Specific examples of the organic solvent are not particularly limited, and examples thereof include nucleic acids.

The aqueous solvent is mixed with the waste organic solvent containing the metal salt in an amount of 50 wt% or less, and the extraction of the metal salt with the aqueous solvent at pH 3 or less may be performed ^at 10 ^° C. to 60 ^° C. In addition, an aqueous solvent is mixed with a waste organic solvent containing 50 wt% or less of the metal salt, and the metal salt is water-based at pH 3 or less. Extracting with a solvent may be performed for 10 minutes to 200 minutes. When the aqueous solvent is mixed with the waste organic solvent containing the metal salt at 50 wt% or less, and the extraction of the metal salt with the aqueous solvent at pH 3 or less is less than 10 minutes, sufficient decomposition of the metal salt and transfer to the aqueous solvent are performed. If the aqueous solvent is mixed with the waste organic solvent containing the metal salt in an amount of 50% by weight or less, and the extraction of the metal salt into the aqueous solvent at pH 3 or less becomes longer than 200 minutes, the operation cost and Economics such as investment costs may decrease.

To describe a more specific example of the step of extracting the metal salt with an aqueous solvent at a pH of 3 or less by mixing an aqueous solvent with a waste organic solvent containing less than 50% by weight of the metal salt, titanium chloride (TiCl) contained in the nucleic acid solvent ₄ ) can be extracted using water, and at this time, reactions such as the following reactions 1 can be performed.

 [Banungsik 1]

6H ₂ 0 + TiCl _4- > Ti (0H) ₄ +4 HC1 + 2H ₂ 0

 In addition, the method of purifying the waste organic solvent may include adjusting the pH of the complex to 5-9.

 In particular, the pH of the mixture can be adjusted to 5 to 9, or 6 to 8. The complex means a mixture of the waste organic solvent and an aqueous solvent, and when the pH of the complex is strongly acidic, the problem may be caused by corrosion of the reactor, and the pH of the complex is greater than 9 When it becomes too large, as the precipitate of the metal salt which arises from the said mixture increases too much, some precipitate may move to an organic solvent layer.

 By adjusting the pH of the mixture to 5 to 9, not only can the acidic substance which is a reaction by-product between the metal salt and the aqueous solvent described above be increased, but the solubility of the metal salt in the aqueous solvent is reduced to precipitate the metal salt in a solid state. By doing so, effective removal may be possible.

That is, adjusting the pH of the complex to 5 to 9 may include neutralizing the complex and precipitating metal salts contained in the complex. In the step of precipitating the metal salt contained in the mixture, the mixture is in a phase-separated state of the organic solvent and the aqueous solvent layered, most of the metal salt Since it is a state dissolved in this aqueous solvent, the metal salt may mainly precipitate in the aqueous solvent layer.

 An example of a method of adjusting the pH of the complex is not particularly limited, and for example, a method of adding a basic substance to the complex may be used. Examples of the basic material are not particularly limited, and basic materials, for example, sodium hydroxide, which are conventionally used in acid salt neutralizing groups, can be used without limitation.

 Adjusting the pH of the mixture to 5 to 9 may be performed for 10 minutes to 200 minutes.

 On the other hand, in the method for purifying the waste organic solvent of the embodiment, the metal salt

Mixing an aqueous solvent with a waste organic solvent containing 50 wt% or less, and extracting the mixture at a pH of 3 or less; And adjusting the pH of the mixture to 5 to 9; may be carried out through a batch or continuous process.

 That is, unlike the conventional process, the method for purifying the waste organic solvent is to decompose the metal chloride by first introducing the process water into the neutralizing drum, and then, secondly, neutralize using a basic material such as an aqueous sodium hydroxide solution. In the batch process, the arithmetic 1 / neutralization process is performed in two stages in one drum, and the washing / neutralizing process may be performed in each drum in the continuous process.

 In addition, the method for purifying the waste organic solvent may include removing the aqueous solvent and the metal salt. Through the step of removing the aqueous solvent and metal salt, it is possible to obtain a purified organic solvent from which impurities are removed from the waste organic solvent.

 The removing of the aqueous solvent and the metal salt may include: separating the aqueous solvent and the metal salt from the waste organic solvent; And distilling the separated waste organic solvent.

 In the step of separating the aqueous solvent and the metal salt from the waste organic solvent, an example of the separation method is not particularly limited, for example, a decanter equipment may be used.

In the decanter, the organic solvent layer and the aqueous solvent layer are separated. It may be issued, so the movement of impurities in the aqueous solvent layer state from the organic solvent layer, ^'separated organic layer may have a clear, transparent aqueous phase

 Distilling the separated organic solvent. Examples of the distillation method is not particularly limited, for example, distillation column equipment can be used. As described above, the separated organic solvent is removed in a state in which impurities are dissolved in an aqueous solvent layer and has a small amount of impurities therein, thereby reducing clogging due to impurities during purification by a distillation column, thereby reducing trouble in the process. Will decrease.

 The method for purifying the waste organic solvent may be repeated two or more times. 【Effects of the Invention】

 According to the present invention, it is possible to provide a method for purifying waste organic solvents which can increase the removal efficiency of impurities contained in the waste organic solvent and prevent equipment damage and increase in economic cost caused by impurities.

 [Brief Description of Drawings]

 FIG. 1 shows an image of the purified organic solvent in Example 1 and Comparative Example 1, in which the purified state is taken.

 [Specific contents to carry out invention]

 The invention is explained in more detail in the following examples. However, the following examples are merely to illustrate the present invention, the content of the present invention is not limited by the following examples.

<Examples 1 to 2: Waste organic solvent purification method>

 Example 1

50 g of hexane containing 24 g of titanium chloride (TiCl ₄ ) was added to the back flask, and 50 g of water was placed in the back flask, followed by stirring at 500 rpm for 90 minutes. At this time, the pH of the semi-aqueous solution was as described in Table 1 below, and the partition coefficient was measured at 966.4.

Then, 20 wt sodium hydroxide (NaOH) aqueous solution was put into a back flask, and stirred at 500 rpm for 60 minutes. After stopping the stirring, the mixture was allowed to stand for 60 minutes to allow sufficient phase separation to occur. PH of the reaction solution at this time is shown in Table 1 As shown.

 With respect to the reaction solution separated in phase, nucleic acid and water were separated using a decanter, and the separated nucleic acid was distilled in a distillation column to obtain purified nucleic acid. Implementation ^] 2

 Except for adjusting the pH of the semi-aqueous solution as shown in Table 1, and proceeded in the same manner as in Example 1. <Comparative Examples 1 to 3: Waste organic solvent purification method>

 Compare U

 The procedure was the same as in Example 1, except that 50 g of water was not added. Compare 12

 Except for adjusting the pH of the semi-aqueous solution as shown in Table 1, and proceeded in the same manner as in Example 1. Compare 13

 Except for adjusting the pH of the reaction solution as shown in Table 1, it was carried out in the same manner as in Example 1.

Experimental Example

 Experimental Example 1 Observation of Purification of Waste Organic Solvent Layer

 With respect to the waste organic solvent purified in Example 1 and Comparative Example 1, the apparent purification state was observed and the results are shown in Figure 1 below. Specifically, Figure 1 (a) is a waste organic solvent purified in Example 1, Figure 1 (b) is a photograph of the waste organic solvent purified in Comparative Example 1.

As shown in Figure 1, in the case of the waste organic solvent purified in Example 1, while clear and transparent, the waste organic solvent purified in Comparative Example 1 was cloudy It was confirmed that the clouded state.

In the case of Example 1, the organic solvent layer and the water layer are separated, and as the metal chloride moves to the water layer, the metal chloride is precipitated and removed only in the water layer, whereas in Comparative Example 1, the organic solvent layer and the water layer All of these seem to be due to the precipitation of metal chlorides and no separation. Experimental Example 2 Analysis of Hydrogen Ion Concentration Index ( _P H)

 In Examples 1 to 2 and Comparative Examples 2 to 3 of the waste organic solvent purification process, the pH of the reaction solution was measured using a pH meter, and the results are shown in Table 1 below. Experimental Example 3 Analysis on Emulsion Production of Phase-Separated Water Layers

 In Examples 1 to 2 and Comparative Examples 2 to 3, the organic solvent and the phase separation of the water layer in the organic solvent purification process was observed with the naked eye, and the results are shown in Table 1 below.

Table 1

 Waste Organic Solvent Purification Conditions and Experimental Results of Examples and Comparative Examples

As shown in Table 1, in the case of the embodiment, by adjusting the pH of the water layer in the range of 5 to 9 by adding sodium hydroxide, it is appropriately controlled that the amount of the emulsion formed from metal chlorides is small or medium You can check. Accordingly, the purification process by the decanter and the distillation column can be carried out more easily. On the other hand, in the case of Comparative Example 2 has a pH of the water layer is too strong acidic 0.72, there is a limit on the corrosion and operation in the post-stage process, the Comparative Example 3 is decane because the liquid-liquid separation is not made while too much emulsion Process is difficult.

Claims

【Claims】 【Claim 1】 Mixing an aqueous solvent with a waste organic solvent containing 50% by weight or less of a metal salt and extracting the metal salt with the aqueous solvent at pH 3 or less; Adjusting the pH of the mixture to 5 to 9; and A method for purifying waste organic solvent, comprising the step of removing the aqueous solvent and metal salt. 【Claim 2】 According to clause 1, In the step of mixing an aqueous solvent with a waste organic solvent containing 50% by weight or less of the metal salt, and extracting the metal salt with an aqueous solvent at pH 3 or less, The solubility of the metal salt in the organic solvent is less than the solubility of the metal salt in the aqueous solvent. Method for purifying waste organic solvent. 【Claim 3】 In clause 1, In the step of mixing an aqueous solvent with a waste organic solvent containing 50% by weight or less of the metal salt, and extracting the metal salt with an aqueous solvent at pH 3 or less, Method for purifying waste organic solvent, wherein the distribution coefficient of the metal salt is 1 to 2000, obtained by Equation 1 below: [Equation 1] Partition coefficient = Solubility of metal salt in aqueous solvent / Solubility of metal salt in organic solvent. [Claim 4] In clause 1, A method for purifying waste organic solvents, wherein the density of the aqueous solvent is greater than that of the organic solvent. 【Claim 5】 In clause 1, A method for purifying waste organic solvents, wherein the weight ratio of the aqueous solvent to the organic solvent is 0.1 to 10. 【Claim 6】 In clause 1, The step of mixing an aqueous solvent with a waste organic solvent containing 50% by weight or less of the metal salt and extracting the metal salt with an aqueous solvent at pH 3 or less, A method for purifying a waste organic solvent, further comprising adding a pH adjusting material to the waste organic solvent containing 50% by weight or less of the metal salt. 【Claim 7】 In clause 1, The metal salt includes a group IVb or Vb metal, and a method for purifying waste organic solvent. 【Claim 8】 In clause 1, A method for purifying a waste organic solvent, wherein the aqueous solvent includes water. 【Claim 9】 In clause 1, The organic solvent is one or more selected from the group consisting of aliphatic hydrocarbons with 1 to 20 carbon atoms, aromatic hydrocarbons with 6 to 20 carbon atoms, aliphatic alcohols with 1 to 20 carbon atoms, aromatic alcohols with 6 to 20 carbon atoms, ketones, and aldehydes. Including, a method for purifying waste organic solvents. [Claim 10] In paragraph 1 A method for purifying waste organic solvents in which an aqueous solvent is mixed with a waste organic solvent containing 50% by weight or less of the metal salt, and the step of extracting the metal salt with an aqueous solvent at pH 3 or less is carried out at 10 ^° C to 60 ^° C. . 【Claim 11】 In clause 1, A method for purifying waste organic solvents, wherein an aqueous solvent is mixed with a waste organic solvent containing 50% by weight or less of the metal salt, and the step of extracting the metal salt with the aqueous solvent at pH 3 or less is performed for 10 to 200 minutes. 【Claim 12】 In clause 1, The step of adjusting the pH of the mixture to 5 to 9 includes the steps of neutralizing the mixture and precipitating the metal salt contained in the mixture. 【Claim 13】 In clause 1, The step of adjusting the pH of the aqueous solvent to 5 to 9 is performed for 10 to 200 minutes. Method for purifying waste organic solvent. 【Claim 14】 In clause 1, The step of removing the aqueous solvent and metal salt is, Separating an aqueous solvent and a metal salt from the waste organic solvent; And a method for purifying waste organic solvent, comprising the step of distilling the separated organic solvent. [Claim 15] In paragraph 1 A method for purifying waste organic solvents, wherein the method for purifying waste organic solvents is repeated two or more times. [Claim 16] In clause 1, The waste organic solvent is obtained from a catalytic synthesis reaction, and a method for purifying the waste organic solvent.