A method for concentrating and purifying triethylamine hydrochloride

Abstract

The application discloses a concentrated purification method of triethylamine hydrochloride, and relates to the technical field of triethylamine hydrochloride preparation.The method comprises the following steps: firstly, triethylamine hydrochloride solid with an organic extractant is placed in a flask; secondly, soft water is added into the flask, and the triethylamine hydrochloride solid is fully dissolved in the soft water; thirdly, the triethylamine hydrochloride solution is transferred into a separatory funnel for static layering, and the upper layer solution is separated; fourthly, the lower layer solution is concentrated by rotary evaporation; fifthly, the concentrated solution is transferred into a centrifuge for centrifugal separation; sixthly, triethylamine hydrochloride wet powder is added into distilled water for secondary dissolution; seventhly, the secondary dissolution solution is sequentially subjected to evaporation concentration and centrifugal separation, so as to obtain triethylamine hydrochloride wet powder with a total phosphorus content of less than 0.03%; and finally, the application relies on two-stage crystallization phase change to separate impurities, effectively reduces the loss of triethylamine hydrochloride in liquid phase, improves the product yield, and simultaneously accurately removes complex organic phosphorus which cannot be removed by water washing.

Description

Technical Field

[0001] This invention belongs to the field of triethylamine hydrochloride preparation technology, specifically relating to a method for concentrating and purifying triethylamine hydrochloride. Background Technology

[0002] Glyphosate is currently the most widely used non-selective herbicide. The glycine process has become the mainstream process for glyphosate production due to its mature technology and suitability for large-scale industrial production. In this process, triethylamine participates in the reaction as the core phase transfer catalyst. After the reaction is completed, triethylamine combines with hydrochloric acid in the system to form triethylamine hydrochloride. This substance is not only a fine chemical intermediate commonly used in the fields of pharmaceuticals, pesticides, dyes, and polymer synthesis, but also a key material that needs to be recycled and reused in glyphosate mother liquor.

[0003] The existing process for triethylamine recycling involves directly separating crude triethylamine hydrochloride from the mother liquor and then purifying and converting it into triethylamine. This reduces acid and alkali consumption and production energy consumption. However, the crude triethylamine hydrochloride obtained directly from the glyphosate mother liquor contains a large amount of phosphorus impurities, with a total phosphorus content of around 0.9%. The current purification process uses a simplified single-stage dissolution-concentration-centrifugation process to treat the crude triethylamine hydrochloride. However, since the phosphorus in the crude product is divided into two categories—free phosphate and complexed organic phosphorus—single-stage treatment can only remove most of the free phosphorus and cannot effectively remove the complexed phosphorus tightly bound to the triethylamine hydrochloride crystals. At the same time, the existing process does not adapt the dissolution water volume, concentration conditions, and centrifugation parameters in stages. The single-component process conditions cannot meet the separation requirements of the two types of phosphorus impurities, making it difficult to meet the standards for high-purity raw material recycling. Summary of the Invention

[0004] The purpose of this invention is to provide a method for concentrating and purifying triethylamine hydrochloride, which can remove phosphorus impurities in different forms in stages, improve the purity of triethylamine hydrochloride recovery, meet the standards for high-purity raw material recycling, and solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for concentrating and purifying triethylamine hydrochloride includes the following steps:

[0007] S1. Place the triethylamine hydrochloride solid containing the organic extractant into a flask, then add soft water to the flask to fully dissolve the triethylamine hydrochloride solid in the soft water to obtain a triethylamine hydrochloride solution.

[0008] S2. Transfer the triethylamine hydrochloride solution to a separatory funnel and allow it to stand for separation. Separate the upper layer solution to obtain the lower layer solution.

[0009] S3. The lower layer solution is concentrated by rotary evaporation. When the amount of water removed is one-third to one-half of the total amount of the initial lower layer solution, the concentration is stopped to obtain the concentrated solution.

[0010] S4. Transfer the concentrate to a centrifuge and centrifuge to obtain triethylamine hydrochloride wet powder;

[0011] S5, triethylamine hydrochloride wet powder is dissolved twice in distilled water to obtain a secondary solution;

[0012] S6. The secondary dissolution solution is successively evaporated, concentrated, and centrifuged to obtain triethylamine hydrochloride wet powder with a total phosphorus content of less than 0.03%.

[0013] Preferably, in step S1, the weight of the soft water added to the flask is 1.0-2.5 times the weight of the triethylamine hydrochloride solid.

[0014] Preferably, the soft water is deionized water or distilled water, and the triethylamine hydrochloride solid needs to be stirred at 50℃-60℃ until fully dissolved during dissolution.

[0015] Preferably, the triethylamine hydrochloride solid containing the organic extractant needs to be screened in a vibrating screener before dissolution. The screen mesh size is controlled to be 80-120 mesh to remove glyphosate solid particles and insoluble inorganic salt mechanical impurities carried in the mother liquor.

[0016] Preferably, in step S2, the triethylamine hydrochloride solution is allowed to stand in a separatory funnel for 3-7 minutes until the boundary between the upper and lower layers is clear and no emulsification occurs.

[0017] Preferably, in step S3, the lower layer solution is concentrated and dehydrated using a rotary evaporator. The heat transfer medium of the rotary evaporator is heat transfer oil, and the vacuum gauge pressure is controlled at 0MPa-0.09MPa and the temperature is 120℃-138℃.

[0018] Preferably, in step S4, the centrifuge is a filter-type rotary drum centrifuge, and during centrifugation, the rotation speed is controlled at 2000 r / min-3000 r / min, and the centrifugation time is 10 min-30 min.

[0019] Preferably, in step S5, the amount of distilled water added is 0.8-1.2 times the weight of the triethylamine hydrochloride wet powder, and the distilled water and the triethylamine hydrochloride wet powder are stirred at 50℃-60℃ until fully dissolved.

[0020] Preferably, in step S6, the secondary dissolution solution is subjected to rotary evaporation using a rotary evaporator at a pressure of 0 MPa-0.09 MPa and a temperature of 120℃-138℃. When the amount of water removed is one-third to one-half of the total amount of the initial lower layer solution, the concentration is stopped to obtain a secondary concentrated solution.

[0021] Preferably, the secondary concentrate is centrifuged using a filter-type rotary drum centrifuge at a speed of 2000 r / min-3000 r / min for 10 min-30 min.

[0022] The method for concentrating and purifying triethylamine hydrochloride proposed in this invention has the following advantages compared with the prior art:

[0023] 1. This invention uses a process of dissolving, separating, concentrating, centrifuging, re-dissolving, re-concentrating and re-centrifuging the triethylamine hydrochloride solid to be purified. By relying on two-stage crystallization phase change to separate impurities, it effectively reduces the loss of triethylamine hydrochloride with the liquid phase, improves product yield, and at the same time accurately removes complexed organophosphorus compounds that cannot be removed by water washing.

[0024] 2. This invention uses vacuum concentration and crystallization phase change to destroy the eutectic and complexing molecular forces of organophosphorus-triethylamine hydrochloride, releasing the bound phosphorus originally encapsulated inside the crystal into the liquid phase, and then completely separating it through secondary centrifugation, thereby stabilizing the total phosphorus to below 0.03% at the molecular level.

[0025] 3. The low total phosphorus triethylamine hydrochloride purified by this invention can not only be reused in glyphosate catalytic systems, but also be supplied as a high-purity intermediate to the pharmaceutical, dye, and polymer synthesis industries, meeting the high-purity raw material standards of multiple industries. Attached Figure Description

[0026] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides, for example Figure 1 The method for concentrating and purifying triethylamine hydrochloride, as shown, includes the following steps:

[0029] S1. Place the triethylamine hydrochloride solid containing the organic extractant into a flask, then add soft water to the flask to fully dissolve the triethylamine hydrochloride solid in the soft water to obtain a triethylamine hydrochloride solution.

[0030] Because the triethylamine hydrochloride solid containing organic extractant also contains unreacted glyphosate particles, silt, insoluble inorganic salts, and other solid mechanical impurities, it needs to be screened in a vibrating screen before dissolution. The screen mesh size is controlled at 80-120 mesh. Screening removes glyphosate solid particles and insoluble inorganic salt mechanical impurities carried in the mother liquor, prevents insoluble solid adsorbed phosphorus impurities from entering the liquid phase, reduces the total phosphorus load of the system, and lowers the pressure of the two-stage purification.

[0031] The initial phosphorus impurities in the triethylamine hydrochloride solid containing organic extractants are complex, including free phosphate, organophosphorus complexes, and phosphorus-amine eutectics, resulting in a high total impurity concentration. The soft water added to the flask is 1.0-2.5 times the weight of the triethylamine hydrochloride solid to provide sufficient solvent capacity to fully dissolve all the triethylamine hydrochloride solid and provide a free migration medium for various phosphorus impurities. If the added water is less than 1.0 times, the solution viscosity is high and the solvent is insufficient, making it easy for phosphorus impurities to be encapsulated and carried by the crystals during concentration and crystallization. If it is more than 2.5 times, the subsequent concentration and evaporation load increases significantly, energy consumption increases, and there is no additional phosphorus removal benefit.

[0032] The soft water is deionized water or distilled water to avoid the introduction of inorganic impurities such as calcium, magnesium, and sulfate from tap water into the product. The triethylamine hydrochloride solid needs to be stirred at 50℃-60℃ until fully dissolved during dissolution. Taking advantage of the characteristic that the solubility of triethylamine hydrochloride increases slightly with temperature, the solid dissolution is accelerated and the dissolution time is shortened. This low temperature range avoids premature precipitation of crystals at high temperatures and simultaneous co-precipitation of phosphorus impurities, ensuring that phosphorus impurities are stably dispersed in the liquid phase.

[0033] S2. Transfer the triethylamine hydrochloride solution to a separatory funnel and allow it to stand for separation. Separate the upper layer solution to obtain the lower layer solution.

[0034] The triethylamine hydrochloride solution is allowed to stand in a separatory funnel for 3-7 minutes until the boundary between the upper and lower layers is clear and no emulsification occurs. Due to the presence of organic extraction solvents in the glyphosate synthesis system, an organic-aqueous two-phase system is formed after dissolution. Standing for 3-7 minutes allows sufficient time for phase separation; the low-viscosity organic phase floats to the top, forming a thin layer, while the aqueous triethylamine hydrochloride solution sinks. Insufficient standing time will result in emulsification, blurred phase interface, and phosphorus impurities encapsulated by the organic solvent mixing into the aqueous phase. Standing for more than 7 minutes provides no impurity removal benefit and prolongs the processing time.

[0035] S3. The lower layer solution is concentrated by rotary evaporation. When the amount of water removed is one-third to one-half of the initial total amount of the lower layer solution, the concentration is stopped, and a concentrated solution is obtained. The lower layer solution is concentrated and dehydrated using a rotary evaporator. The heat transfer medium of the rotary evaporator is heat transfer oil. Using heat transfer oil as the heat transfer medium has a large heat capacity and uniform tube wall temperature, avoiding local overheating caused by electric heating. The vacuum gauge pressure is controlled at 0MPa-0.09MPa and the temperature is 120℃-138℃. Efficient dehydration is achieved without reaching the decomposition temperature of triethylamine hydrochloride (245℃). Local high temperatures in a high chloride ion system will accelerate the electrochemical corrosion of stainless steel / carbon steel equipment and generate metallic chloride impurities. The uniform heating of heat transfer oil inhibits corrosion side reactions. The evaporation rate is extremely low below 120℃, and local carbonization and sintering of materials are likely to occur above 138℃.

[0036] S4. The concentrated solution is transferred to a centrifuge for centrifugation to obtain triethylamine hydrochloride wet powder. The centrifuge is a filter-type rotary drum centrifuge. During centrifugation, the rotation speed is controlled at 2000 r / min-3000 r / min, and the centrifugation time is 10 min-30 min. After concentration, the solution forms a suspension system of triethylamine hydrochloride crystals and phosphorus-containing mother liquor. Centrifugation force above 2000 r / min can overcome the interfacial tension between the crystals and the mother liquor, and peel the mother liquor adsorbed with free phosphorus from the crystal surface. If the rotation speed is below 2000 r / min, the centrifugation force is insufficient, and a large amount of phosphorus-containing mother liquor is entrained in the wet powder. If the rotation speed is above 3000 r / min, the strong shear force breaks the crystals to generate ultrafine crystals, the specific surface area increases dramatically, more phosphorus-containing mother liquor is adsorbed, and the phosphorus removal effect decreases in the opposite direction. The 10-30 min range ensures that the solid and liquid are fully separated. If the time is insufficient, the separation is incomplete. If the time is exceeded, there is no benefit and the energy consumption is increased. The filter-type rotary drum can intercept the crystals, and the liquid phase phosphorus-containing mother liquor is discharged through the filter cloth.

[0037] S5, triethylamine hydrochloride wet powder is dissolved twice in distilled water to obtain a secondary solution;

[0038] The amount of distilled water added is 0.8-1.2 times the weight of the triethylamine hydrochloride wet powder, and the distilled water and triethylamine hydrochloride wet powder are stirred at 50℃-60℃ until fully dissolved; the residual phosphorus after primary purification is a complexed organic phosphorus tightly bonded to triethylamine hydrochloride, so the amount of water in the solution needs to be reduced to increase the concentration factor; a low water volume of 0.8-1.2 times to dissolve the wet powder significantly increases the supersaturation of the system under the same evaporation and dehydration, crystals are quickly expelled, intermolecular forces are broken, and complexed phosphorus is squeezed out into the liquid phase; if the water volume exceeds 1.2 times, the concentration factor is insufficient and the eutectic / complex structure cannot be dissociated; if the water volume is less than 0.8 times, the material is too viscous to be completely dissolved; a constant temperature of 50-60℃ ensures that the wet powder is fully dissolved and there is no local agglomeration of dry material;

[0039] S6. The secondary dissolution solution is successively evaporated, concentrated, and centrifuged to obtain triethylamine hydrochloride wet powder with a total phosphorus content of less than 0.03%;

[0040] The secondary dissolution solution is evaporated using a rotary evaporator at a pressure of 0-0.09 MPa and a temperature of 120-138°C. Concentration is stopped when the amount of water removed is one-third to one-half of the initial lower layer solution, yielding a secondary concentrate. This secondary dissolution solution contains dissociated complexed organophosphorus compounds and requires the same mild vacuum concentration conditions as the primary solution to ensure stable crystallization of triethylamine hydrochloride while continuously retaining free and dissociated phosphorus in the liquid phase. Standardized temperature and pressure parameters simplify equipment operation and control, eliminating the need for segmented adjustments. The heating and vacuum systems are suitable for automated continuous production. High temperatures and normal pressures can cause product deterioration and co-precipitation of phosphorus impurities. The secondary concentrate is centrifuged in a filter-type rotary drum centrifuge at a speed of 2000-3000 r / min for 10-30 min. The mother liquor containing dissociated and complexed phosphorus is adsorbed on the crystal surface in the secondary concentrate. The same centrifugation range provides matching centrifugal force to completely remove the adsorbed mother liquor. The parameters are the same as those of the primary centrifuge, simplifying the operation of the process. The filter drum retains high-purity crystals, and the phosphorus-rich mother liquor is separated and recovered.

[0041] The crude product is dissolved in a high-expansion soft water solution, and organic solvents entrained in the glyphosate system are removed by liquid-liquid separation. The concentration depth is controlled by rotary evaporation with vacuum heat transfer oil, followed by crystallization and centrifugation to preferentially remove most of the free phosphorus impurities. The primary triethylamine hydrochloride wet powder is then dissolved a second time with low-expansion distilled water to increase the supersaturation of the system and destroy the complex and eutectic structure formed by triethylamine hydrochloride and organic phosphorus. The product is then concentrated and centrifuged again under the same conditions to completely remove the bound phosphorus originally encapsulated and bonded inside the crystal to the mother liquor. This achieves graded removal of phosphorus impurities and produces high-purity triethylamine hydrochloride wet powder, which can be directly neutralized to prepare triethylamine for reuse in the glyphosate synthesis process. At the same time, it recovers phosphorus resources in the mother liquor, reducing phosphorus loss and waste.

[0042] For example, as a preferred embodiment, 1000g of crude triethylamine hydrochloride solid obtained from the separation of glyphosate mother liquor is taken, and the initial total phosphorus content is determined to be 0.91%. The solid is then sieved using a 100-mesh vibrating sieve to remove entrained glyphosate particles and insoluble inorganic salts. The sieved solid is transferred to a stirred flask, and 2000g of deionized soft water (2.0 times the solid weight) is added. The mixture is heated to 55°C and stirred until the solid is completely dissolved. The entire solution is transferred to a separatory funnel and allowed to stand for 6 minutes. When the interface between the two phases is clear and there is no emulsification, the upper organic phase is separated and discarded. The lower aqueous phase is sent to a rotary evaporator, heated with heat transfer oil at 130°C, and the vacuum degree is controlled at 0.06MPa. The mixture is then vacuum concentrated and dehydrated to the total system. After dehydration to 40%, heating was stopped to obtain a primary concentrate. The concentrate was then fed into a filter-type rotary centrifuge at 2500 rpm for 20 minutes. The primary wet powder of triethylamine hydrochloride was collected, and a sample was taken for total phosphorus analysis, finding it to be 0.45%. An equal volume of distilled water (1.0 times the weight of the wet powder) was added to the primary wet powder, and the mixture was stirred at 55°C to dissolve it a second time. The second solution was transferred to the same rotary evaporator and concentrated to 40% dehydration under 130°C and 0.06 MPa vacuum conditions. The secondary concentrate was then centrifuged again at 2500 rpm for 20 minutes, and the final purified wet powder was collected. The total phosphorus content was found to be 0.028%, representing a total phosphorus removal rate of 96.9%. The purified mother liquor was collected and the phosphorus component was recovered for recycling.

[0043] For example, as another preferred embodiment, 1000g of crude triethylamine hydrochloride solid with an initial total phosphorus content of 0.88% is sieved through a 90-mesh vibrating screen to remove impurities; 1500g of distilled water (1.5 times the amount) is added and stirred at 50°C until completely dissolved; the mixture is allowed to stand in a separatory funnel for 5 minutes to separate the upper organic solvent layer; the lower solution is rotary evaporated using heat transfer oil at 135°C and a vacuum of 0.08MPa to dehydrate to a total water content of 45%; the mixture is centrifuged at 3000r / min for 15 minutes, resulting in a first-stage wet powder with a total phosphorus content of 0.48%; 0.9 times the amount of distilled water is added to the wet powder and stirred at 60°C for a second dissolution; the concentration is repeated at 135°C and a vacuum of 0.08MPa, followed by centrifugation at 3000r / min for 15 minutes; the final wet powder has a total phosphorus content of 0.025%, with a total phosphorus removal rate of 97.2%.

[0044] For example, as another preferred embodiment, 1000g of crude triethylamine hydrochloride solid with an initial total phosphorus content of 0.92% was pretreated by sieving through a 120-mesh sieve; 2500g of deionized water (2.5 times the amount) was added and stirred at 60°C to dissolve; the mixture was allowed to stand in a separatory funnel for 7 minutes to separate the organic phase; the heat transfer oil was rotary evaporated at 120°C and under a vacuum of 0.09MPa to dehydrate to a total water content of 35%; the mixture was centrifuged at 2000r / min for 30 minutes, resulting in a total phosphorus content of 0.42% in the first-stage wet powder; the wet powder was dissolved in 1.2 times the amount of distilled water at 50°C; after concentration under the same vacuum temperature, it was centrifuged at 2000r / min for 30 minutes; the final wet powder had a total phosphorus content of 0.030%, with a total phosphorus removal rate of 96.7%.

[0045] For example, as a comparative scheme, 1000g of the same crude product with an initial total phosphorus content of 0.90% was dissolved in twice the amount of soft water, separated, and then subjected to only one rotary evaporation and centrifugation process without secondary dissolution, concentration, or centrifugation. After centrifugation, the total phosphorus content of the wet powder was 0.44%, with a phosphorus removal rate of only 51.1%. The total phosphorus content of the finished product far exceeded the 0.03% usage standard and could not be directly reused in the glyphosate synthesis process, resulting in a significant loss of phosphorus resources.

[0046] It should be noted that the total phosphorus content of all materials in this invention is uniformly determined using potassium persulfate digestion and ammonium molybdate spectrophotometry. This method simultaneously detects free inorganic phosphate, organic phosphorus complexed with triethylamine hydrochloride, and phosphorus-amine eutectic bound phosphorus in the sample, avoiding the problems of missed detection of complexed phosphorus and data distortion caused by water-soluble detection alone. The supporting testing, sampling, and baseline specifications are as follows:

[0047] Sampling status and sampling operation: Materials from each section are sampled differently according to the node. The crude triethylamine hydrochloride solid to be purified is the dry solid after sieving. After impurity removal by 80-120 mesh vibrating sieve, the sample is reduced by quartering. The wet powder from the first centrifugation and the wet powder from the second centrifugation are continuously collected and mixed during the centrifuge unloading stage. The sample is sealed immediately after sampling to prevent the surface mother liquor from evaporating and concentrating, which would raise the phosphorus detection result. The sampling amount of solid in the central control is not less than 5g, and the sampling amount of dry crude product is not less than 2g. Two parallel samples are prepared simultaneously for each group of samples. If the parallel detection deviation is greater than 5%, resampling and retesting are required. The phosphorus-containing mother liquor produced by centrifugation is sampled separately for phosphorus recovery balance.

[0048] Definition of dry basis and wet basis measurement: In all embodiments of the method of this invention, the total phosphorus index (crude product 0.88%~0.92%, first-grade wet powder 0.42%~0.48%, finished product ≤0.03%) is based on wet basis. Wet basis refers to the direct weighing and detection of centrifuged wet powder that has not been dried and has been saturated with crystallization mother liquor, without deducting surface free moisture, which is suitable for the rapid determination needs of continuous production in the workshop. If it is used for the calibration of high-purity raw materials for export in the pharmaceutical and dye industries, the wet powder needs to be dried in an oven at 105℃ to constant weight to obtain absolutely dry material, which is then converted to dry basis total phosphorus. The conversion formula is: dry basis total phosphorus = wet basis total phosphorus ÷ (1 - moisture content of wet powder).

[0049] Detection operation, detection limit and determination interval: Weigh 0.2-0.5 g of wet-based sample (0.1-0.2 g for dry crude product), add deionized water to fully dissolve it, then add 5% potassium persulfate solution, perform digestion for 30 min under high-pressure steam conditions of 120°C and 0.12 MPa to completely destroy the complexation and co-crystal structures of organic phosphorus and triethylamine hydrochloride. After cooling and constant volume adjustment, the acidity of the system is adjusted, and the ammonium molybdate-ascorbic acid color development system is adopted for spectrophotometric determination at a wavelength of 700 nm; the detection limit of this method is 0.001% (wet basis), the lower limit of quantitation is 0.003%, and the linear determination range covers 0.001%-1.5% on wet basis, which can accurately distinguish gradient finished materials of 0.025%, 0.028% and 0.030%, fully meeting the index control requirement that the total phosphorus of the finished product of the present invention is ≤ 0.03%; when the total phosphorus of the sample exceeds 1.5%, the digestion solution needs to be diluted and retested.

[0050] Quality control and qualification judgment rules: A pure water reagent blank is set synchronously during the detection process to eliminate exogenous phosphorus interference, and the reliability of the method is verified by the standard addition recovery of organic phosphorus reference materials, with the standard addition recovery rate controlled at 95%-105%; the low-phosphorus triethylamine hydrochloride wet powder obtained by secondary centrifugation is judged as qualified when the detected total phosphorus is ≤ 0.030% (wet basis). If the detected value exceeds 0.030%, the material needs to be re-subjected to the secondary dissolution step S5 and the concentration centrifugation step S6; when the detected value is lower than the method detection limit of 0.001%, the total phosphorus is marked as < 0.001% in the test report. Through this total phosphorus detection system, the proportions of free inorganic phosphorus and complexed organic phosphorus can be calculated respectively, which intuitively verifies the technical effect of the two-stage crystallization phase change process of the present invention in dissociating the phosphorus-amine complex structure and removing different forms of phosphorus impurities in stages, and clearly reflects the performance difference that single-stage purification can only remove free phosphorus while two-stage purification can deeply strip the bound organic phosphorus inside the crystal.

[0051] In conclusion, the low total phosphorus triethylamine hydrochloride purified by the present invention can not only be reused in the glyphosate catalytic system, but also be supplied as a high-purity intermediate to the pharmaceutical, dye and polymer synthesis industries, meeting the high-purity raw material standards of multiple industries.

[0052] Finally, it should be noted that the above description is only the preferred embodiments of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall all be included in the protection scope of the present invention.

Claims

1. A method for concentrating and purifying triethylamine hydrochloride, characterized in that: Includes the following steps: S1. Place the triethylamine hydrochloride solid containing the organic extractant into a flask, then add soft water to the flask to fully dissolve the triethylamine hydrochloride solid in the soft water to obtain a triethylamine hydrochloride solution. S2. Transfer the triethylamine hydrochloride solution to a separatory funnel and allow it to stand for separation. Separate the upper layer solution to obtain the lower layer solution. S3. The lower layer solution is concentrated by rotary evaporation. When the amount of water removed is one-third to one-half of the total amount of the initial lower layer solution, the concentration is stopped to obtain the concentrated solution. S4. Transfer the concentrate to a centrifuge and centrifuge to obtain triethylamine hydrochloride wet powder; S5, triethylamine hydrochloride wet powder is dissolved twice in distilled water to obtain a secondary solution; S6. The secondary dissolution solution is successively evaporated, concentrated, and centrifuged to obtain triethylamine hydrochloride wet powder with a total phosphorus content of less than 0.03%.

2. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S1, the weight of the soft water added to the flask is 1.0-2.5 times the weight of the triethylamine hydrochloride solid.

3. The method for concentrating and purifying triethylamine hydrochloride according to claim 2, characterized in that: The soft water is deionized water or distilled water, and the triethylamine hydrochloride solid needs to be stirred at 50℃-60℃ until fully dissolved during dissolution.

4. The method for concentrating and purifying triethylamine hydrochloride according to claim 3, characterized in that: Before dissolving, the triethylamine hydrochloride solid containing organic extractant needs to be screened in a vibrating screen with a screen mesh size of 80-120 mesh to remove glyphosate solid particles and insoluble inorganic salt mechanical impurities carried in the mother liquor.

5. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S2, the triethylamine hydrochloride solution is allowed to stand in a separatory funnel for 3-7 minutes until the boundary between the upper and lower layers is clear and no emulsification occurs.

6. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S3, the lower layer solution is concentrated and dehydrated using a rotary evaporator. The heat transfer medium of the rotary evaporator is heat transfer oil, and the vacuum gauge pressure is controlled at 0MPa-0.09MPa and the temperature is 120℃-138℃.

7. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S4, the centrifuge is a filter-type rotary drum centrifuge. During centrifugation, the rotation speed is controlled at 2000 r / min-3000 r / min, and the centrifugation time is 10 min-30 min.

8. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S5, the amount of distilled water added is 0.8-1.2 times the weight of the triethylamine hydrochloride wet powder, and the distilled water and the triethylamine hydrochloride wet powder are stirred at 50℃-60℃ until fully dissolved.

9. The method for concentrating and purifying triethylamine hydrochloride according to claim 1, characterized in that: In step S6, the secondary dissolution solution is subjected to rotary evaporation in a rotary evaporator at a pressure of 0 MPa-0.09 MPa and a temperature of 120℃-138℃. When the amount of water removed is one-third to one-half of the total amount of the initial lower layer solution, the concentration is stopped to obtain a secondary concentrated solution.

10. The method for concentrating and purifying triethylamine hydrochloride according to claim 9, characterized in that: The secondary concentrate was centrifuged using a filter-type rotary drum centrifuge at a speed of 2000 r / min-3000 r / min for 10 min-30 min.

Images