CN103936600A - Method for purifying cationic etherifying agent via phosphate ester extraction agent - Google Patents

Abstract

The invention discloses a method for purifying a cationic etherification agent with a phosphate ester extractant. The crude product of the cationic etherification agent is extracted and purified by using a phosphoric acid ester compound as an extraction agent, so as to remove residual epichlorohydrin and 1,3-Dichloro-2-propanol. While extracting, regenerate the extractant that is finally rich in epichlorohydrin and 1,3-dichloro-2-propanol after extraction, use lye to maintain the regeneration environment in an alkaline environment, and extract after regeneration The agent is recycled for the extraction of the crude product of the cationic etherification agent, and the recovered epichlorohydrin is recycled to the synthesis of the cationic etherification agent. Compared with the prior art, the invention has the advantages of simple process, convenient operation, low equipment investment, economical and environmental protection.

Description

Method for Purifying Cationic Etherifying Agent with Phosphate Ester Extractant

technical field

The invention belongs to a purification process of fine chemical products, and more specifically relates to a method for extraction, purification and regeneration of a cationic etherification agent.

Background technique

At present, most of the cationic etherifying agents used in the domestic production of high-quality modified starch are imported from abroad. However, with the continuous development of natural product modified chemicals such as starch, the amount of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC), as an etherification agent with excellent performance, will continue to increase. Therefore, it is of great significance to seek the optimal process for the production of CHPTMAC to improve the market competitiveness of etherifying agents in my country. However, the cationic etherification agent crude products produced by domestic manufacturers contain high contents of epichlorohydrin (ECH) and 1,3-dichloro-2-propanol (DCP), reaching 1622 mg·kg ^-1 and 18472 mg·kg -1 respectively ^{. 1.} The product is easy to crystallize. The presence of epichlorohydrin and 1,3-dichloro-2-propanol makes it easy to cross-link with starch, which seriously affects the application performance of cationic starch.

Most domestic cationic starch manufacturers use steam stripping to remove epichlorohydrin and 1,3-dichloro-2-propanol. The stripping process can effectively reduce the content of organic impurities, but it also faces high energy consumption (purifying one ton of crude product CHPTMAC consumes 1.0-1.5 tons of water vapor), and at the same time there is a large amount of gas containing epichlorohydrin and 1,3- Dichloro-2-propanol organic wastewater is difficult to deal with. According to statistics, for every 1 ton of crude product purified, an average of 1 to 1.5 tons of organic wastewater is produced, and the main substances epichlorohydrin and 1,3-dichloro-2-propanol are highly toxic and carcinogenic to humans. According to my country's comprehensive sewage discharge standard, the total chlorine content of wastewater is <0.5mg/L, and the low-concentration organic wastewater produced by steam stripping has a concentration of 1 to 1.5% of the two impurities, which is much higher than the national sewage discharge standard. Because the lower the impurity content in the wastewater, the more difficult it is to treat. Therefore, it is more difficult and costly to treat the organic wastewater produced by the cationic etherification agent stripping method. This is also a major technical bottleneck restricting the sustainable development of enterprises. Therefore, in order to study a more reasonable aftertreatment method, it is an important problem to be solved at present to reduce the pollution to the environment while effectively removing organic impurities.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a highly efficient, economical and environmentally friendly method for purifying cationic etherifying agents. The production cost is reduced, and the environmental pollution problem caused by the use of the steam stripping method is reduced, so that the whole process has good economic and environmental benefits. Combined with the application field of cationic etherification agent, the requirement for extraction process purification is to select the extraction agent with a large extraction coefficient, low toxicity or even non-toxicity, and the extraction agent can be reused many times and easily regenerated to greatly reduce production costs.

In order to achieve the above purpose, a variety of extractants were selected and investigated, such as toluene, dichloromethane, ether, chloroform and several kinds of phosphate extractants to extract the crude product of cationic etherification agent. The analysis shows that the phosphate ester extractant is more suitable for the extraction and purification of cationic etherification agent. For this type of extractant, the extraction process conditions were determined, the effect of the regeneration process conditions on the regeneration effect was investigated, and the optimal regeneration process conditions were determined.

Technical purpose of the present invention is achieved through the following technical solutions:

A method for purifying cationic etherifying agent with phosphate ester extractant, extracting and purifying the crude product of cationic etherifying agent with phosphoric acid ester compound as extractant, so as to remove residual epichlorohydrin and 1,3 in the cationic etherifying agent product - Dichloro-2-propanol. While extracting, regenerate the extractant that is finally rich in epichlorohydrin and 1,3-dichloro-2-propanol after extraction, use lye to maintain the regeneration environment in an alkaline environment, and extract after regeneration The agent is recycled for the extraction of the crude product of the cationic etherification agent, and the recovered epichlorohydrin is recycled to the synthesis of the cationic etherification agent.

In the above-mentioned technical scheme, the volume ratio of the crude product of the cationic etherification agent to the extractant is 1: (0.4-1).

In the above technical solution, the extraction temperature is room temperature 20-25 degrees Celsius, and the extraction pressure is 1 atmosphere.

In the above technical scheme, the cationic etherification agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride, and the content of epichlorohydrin in the crude product of the cationic etherification agent is as high as 1500 mg·kg ^-1 or more, 1,3 The content of -dichloro-2-propanol is as high as 15472 mg·kg ^-1 or more.

In the above technical solution, the phosphate compound is selected from tributyl phosphate, triisobutyl phosphate, trihexyl phosphate or trioctyl phosphate.

In the above technical scheme, the regeneration temperature of the extractant is 60-140° C., and the regeneration time is 2-6 hours.

In the above technical scheme, the alkali solution is an aqueous solution of an inorganic base or an organic quaternary ammonium base, the concentration of which is 3.8-8.5 wt% by mass, and the described inorganic base is selected from NaOH, KOH or Na ₂ CO ₃ ; the described The organic quaternary ammonium base is selected from tetrabutylammonium hydroxide, trimethylethylammonium hydroxide or tetraethylammonium hydroxide.

When implementing the above extraction scheme, a three-stage countercurrent extraction process is selected, as shown in Figure 1. The three extraction units are connected by pipelines, and the feeding and discharging directions of the extractant and the crude product are selected to realize the countercurrent extraction process of the extractant and the crude product in each extraction unit. After the final discharge of the third extraction unit, the impurities in the crude product have met the product requirements, and the extraction agent enters the regeneration unit at the same time. After regeneration, the extraction agent is returned to the extraction unit for recycling, and epichlorohydrin is recycled to the synthetic cationic ether used in chemicals.

The above-mentioned three-stage countercurrent extraction method is adopted, and continuous operation or intermittent operation is adopted according to actual needs.

Compared with the prior art, the present invention has the following advantages: 1. Simple process and easy operation; 2. Less investment in equipment (basically zero investment); 3. Phosphate ester extractant has a high boiling point, low solubility in water, and excellent properties. Stable characteristics; 4. Phosphate ester extractant has good effect after regeneration, economical and environmental protection.

Description of drawings

Figure 1 is a schematic diagram of the three-stage countercurrent continuous extraction process in the technical solution of the present invention, wherein A is the first-stage extraction unit, B is the second-stage extraction unit, C is the third-stage extraction unit, D is the regeneration unit, and 1 is the extraction agent entering the pipeline (light phase feed pipeline), 2 is the crude product inlet pipeline (heavy phase feed pipeline), 3 and 6 are crude product connection pipelines, 4 and 5 are extraction agent connection pipelines, and 7 is crude product output pipeline. The feed pipeline (heavy phase discharge pipeline), 8 is the extractant discharge pipeline (light phase discharge pipeline), 9 is the epichlorohydrin discharge pipeline, and 10 is the extractant return pipeline.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

Embodiment one

Take trioctyl phosphate as an example to purify cationic etherification agent:

1. Extraction

The content of epichlorohydrin in the crude product cationic etherification agent 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1622mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 18472mg·kg ^-1 . The extraction agent is V _{crude product} : V _{extraction agent} = 1:0.7 ratio, after one continuous extraction, the epichlorohydrin content in the cationic etherification agent is 15 mg·kg ^-1 , 1,3-dichloro-2-propane The content of alcohol is 32mg·kg ^-1 ; after two consecutive extractions, the content of epichlorohydrin in the cationic etherification agent is 6mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 12mg·kg ^-1 .

2. Regeneration

The regeneration conditions of trioctyl phosphate: the concentration is 7% NaOH aqueous solution, the temperature is 120 ° C, the regeneration time is 3 hours, after recycling 6 times, epichlorohydrin and 1,3-dichloro-2- The content of propanol is still lower than 40 mg·kg ^-1 . It shows that trioctyl phosphate can be reused many times after the regeneration process, which can effectively save the cost of use.

Embodiment two

Take triisobutyl phosphate as the extraction agent to purify cationic etherification agent as an example:

1. Extraction

The content of epichlorohydrin in the crude product cationic etherification agent 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1622mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 18472mg·kg ^-1 . The extraction agent is V _{crude product} : V _{extraction agent} = 1:0.8 ratio, after one continuous extraction, the epichlorohydrin content in the cationic etherification agent is 36 mg·kg ^-1 , 1,3-dichloro-2-propane The content of alcohol is 70mg·kg ^-1 ; after two consecutive extractions, the content of epichlorohydrin in the cationic etherification agent is 10mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 15mg·kg ^-1 ; After 4 consecutive extractions, epichlorohydrin and 1,3-dichloro-2-propanol were not detected by the cationic etherifying agent.

2. Regeneration

The regeneration conditions of triisobutyl phosphate: the concentration is 6% Na ₂ CO ₃ aqueous solution, the temperature is 100°C, the regeneration time is 4 hours, after recycling 4 times, epichlorohydrin and 1,3- The content of dichloro-2-propanol was still lower than 50 mg·kg ^-1 . It shows that triisobutyl phosphate can be reused many times after the regeneration process, which can effectively save the cost of use.

Embodiment three

Take tributyl phosphate as the extraction agent to purify cationic etherification agent as an example:

1. Extraction

The ECH content in the crude product cationic etherifying agent 3-chloro-2-hydroxypropyltrimethylammonium chloride was 1885 mg·kg ^-1 , and the DCP content was 23265 mg·kg ^-1 . The extraction agent is V _{crude product} : V _{extraction agent} = 1:1.1 ratio, after one continuous extraction, the epichlorohydrin content in the cationic etherification agent is 46 mg·kg ^-1 , 1,3-dichloro-2-propane The content of alcohol is 82mg·kg ^-1 ; after two consecutive extractions, the content of epichlorohydrin in the cationic etherification agent is 18mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 25mg·kg ^{- 1} .

2. Regeneration

The regeneration conditions of tributyl phosphate: the concentration is 5% tetrabutylammonium hydroxide aqueous solution, the temperature is 120°C, the regeneration time is 6 hours, after recycling 6 times, epichlorohydrin and 1,3- The content of dichloro-2-propanol is lower than 50 mg·kg ^-1 . It shows that tributyl phosphate can be reused many times after the regeneration process, which can effectively save the cost of use.

Embodiment four

Take trihexyl phosphate as the extraction agent to purify cationic etherification agent as an example:

1. Extraction

The content of epichlorohydrin in the crude product cationic etherification agent 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1895mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 20269mg·kg ^-1 . The extraction agent is V _{crude product} : V _{extraction agent} = 1:0.6 ratio, after one continuous extraction, the epichlorohydrin content in the cationic etherification agent is 48 mg·kg ^-1 , 1,3-dichloro-2-propane The content of alcohol is 85 mg·kg ^-1 ; after two consecutive extractions, the content of epichlorohydrin in the cationic etherification agent is 15 mg·kg ^-1 , and the content of 1,3-dichloro-2-propanol is 25 mg·kg ^-1 .

2. Regeneration

The regeneration conditions of trihexyl phosphate: the concentration is 5% tetraethylammonium hydroxide aqueous solution, the temperature is 100°C, the regeneration time is 6 hours, after recycling 4 times, epichlorohydrin and 1,3- The content of dichloro-2-propanol is lower than 50 mg·kg ^-1 . It shows that trihexyl phosphate can be reused many times after the regeneration process, which can effectively save the cost of use.

When implementing the above-mentioned four embodiment schemes, select the three-stage countercurrent extraction process, as shown in Figure 1, wherein A is a primary extraction unit, B is a secondary extraction unit, C is a tertiary extraction unit, and D is a regeneration unit. 1 is the extraction agent inlet pipeline (light phase feed pipeline), 2 is the crude product inlet pipeline (heavy phase feed pipeline), 3 and 6 are crude product connection pipelines, 4 and 5 are extraction agent connection pipes 7 is the crude product discharge pipeline (heavy phase discharge pipeline), 8 is the extraction agent discharge pipeline (light phase discharge pipeline), 9 is the epichlorohydrin discharge pipeline, and 10 is the extraction agent return line. The three extraction units are connected by pipelines, and the feeding and discharging directions of the extractant and the crude product are selected to realize the countercurrent extraction process of the extractant and the crude product in each extraction unit. After the final discharge of the third extraction unit, the impurities in the crude product have met the product requirements, and the extraction agent enters the regeneration unit at the same time. After regeneration, the extraction agent is returned to the extraction unit for recycling, and epichlorohydrin is recycled to the synthetic cationic ether used in chemicals.

The present invention has been described as an example above, and it should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacements that can be made by those skilled in the art without creative labor all fall within the scope of this invention. protection scope of the invention.

Claims (10)

1. The method for purifying cationic etherification agent with phosphate ester extractant, is characterized in that, extracts and purifies the crude product of cationic etherification agent with phosphoric acid ester compound as extraction agent, to remove residual epoxy in the cationic etherification agent product Chloropropane and 1,3-dichloro-2-propanol, wherein the cationic etherification agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride, the crude product of the cationic etherification agent and the extractant The volume ratio is 1:(0.4-1), and the phosphate compound is selected from tributyl phosphate, triisobutyl phosphate, trihexyl phosphate or trioctyl phosphate. 2. the method for the purification cationic etherification agent of phosphoric acid ester extraction agent according to claim 1, is characterized in that, while carrying out extraction, will be rich in epichlorohydrin and 1,3-dichloro- The extraction agent of 2-propanol is regenerated, and the regeneration environment is maintained in an alkaline environment by using lye. The regenerated extraction agent is recycled for the extraction of the crude product of the cationic etherification agent, and the recycled epichlorohydrin is recycled to the synthetic Used in cationic etherification agent. 3. The method for purifying cationic etherification agent with phosphoric acid ester extractant according to claim 1 or 2, characterized in that the extraction temperature is room temperature at 20-25 degrees Celsius, and the extraction pressure is 1 atmosphere. 4. according to claim 1 or 2 described method of phosphate ester extraction agent purifying cationic etherification agent, it is characterized in that, in the crude product of cationic etherification agent, epichlorohydrin content is up to more than 1500mg kg ^-1 , 1, The content of 3-dichloro-2-propanol was as high as 15472 mg·kg ^-1 or more. 5 . The method for purifying cationic etherification agent with phosphate ester extractant according to claim 2 , characterized in that, the regeneration temperature of the extractant is 60-140° C., and the regeneration time is 2-6 h. 6. the method for phosphate ester extraction agent purifying cationic etherifying agent according to claim 2, is characterized in that, described lye is the aqueous solution of inorganic alkali or organic quaternary ammonium alkali, and concentration is mass percent 3.8-8.5wt% , the inorganic base is selected from NaOH, KOH or Na ₂ CO ₃ ; the organic quaternary ammonium base is selected from tetrabutylammonium hydroxide, trimethylethylammonium hydroxide or tetraethylammonium hydroxide. 7. according to claim 1 or the method for phosphate ester extraction agent purification cationic etherification agent described in 2, it is characterized in that, when implementing extraction scheme, select three-stage countercurrent extraction process, utilize pipeline to link three extraction units , and by selecting the feeding and discharging directions of the extractant and the crude product, to realize the countercurrent extraction process of the extractant and the crude product in each extraction unit, after the final discharge of the third extraction unit, the crude product Impurities have met product requirements. 8. the method for phosphate ester extraction agent purifying cationic etherifying agent according to claim 2, is characterized in that, when implementing extraction scheme, selects three-stage countercurrent extraction process, utilizes pipeline to be connected with three extraction units, and By selecting the feeding and discharging directions of the extractant and the crude product, the countercurrent extraction process of the extractant and the crude product in each extraction unit is realized. After the final discharge of the third extraction unit, the impurities in the crude product have been eliminated. To meet the product requirements, the extractant enters the regeneration unit at the same time. After regeneration, the extractant is returned to the extraction unit for recycling, and epichlorohydrin is recycled to the synthetic cationic etherification agent for use. 9. The method for purifying cationic etherification agent with phosphoric acid ester extractant according to claim 7, characterized in that, a three-stage countercurrent extraction method is adopted, and continuous operation or intermittent operation is adopted according to actual needs. 10. The method for purifying cationic etherification agent with phosphoric acid ester extractant according to claim 8, characterized in that, a three-stage countercurrent extraction method is adopted, and continuous operation or intermittent operation is adopted according to actual needs.