Device for producing glycine by iodine catalysis method

Abstract

The utility model discloses a device for producing glycine by using an iodine catalysis method, which is characterized in that a chloride synthesis kettle is connected with a filtrate receiving tank A through a chloride centrifugal machine; the filtrate receiving tank A is connected with a glycine synthesis kettle through a filtrate A transfer pump; the glycine synthesis kettle is connected with a glycine centrifugal machine; the glycine centrifugal machine is connected with the filtrate receiving tank B; and the filtrate receiving tank B is connected with the methanol evaporation tank through a filtrate B transfer pump. The glycine synthesis kettle is connected with an ammonia gas pipeline and a urotropine pipeline; and the upper part of the glycine centrifugal machine is connected with a material washing methanol pipeline, a nitrogen pipeline and an emptying pipeline. Efficient separation of glycine crystals and ammonium chloride crystals is achieved through two-step chemical reactions and solubility differences, a glycine product meeting glyphosate synthesis and reaching the national standard (the main content is larger than or equal to 98.5%, and the chlorine radical is smaller than or equal to 0.4%) can be obtained, filtrate can be recycled, the consumption of urotropine and steam is greatly reduced, clean production is completely achieved, and the method has industrial application value.

Description

Technical Field

[0001] The utility model discloses a device for producing glycine by an iodine catalysis method, belongs to the technical field of chemical production, and particularly relates to a new alcohol phase synthesis process. Background Art

[0002] As an important fine chemical product, glycine is widely used in the pharmaceutical, food, daily chemical and agricultural industries. It is the main raw material for the synthesis of glyphosate, the most widely used, highest-share and most active green herbicide in the world. From 2012 to 2020, the domestic glycine production has grown steadily, from 280,000 tons / year to 400,000 tons / year. At present, the existing glycine preparation methods in China are mainly chloroacetic acid aqueous phase ammonolysis and alcohol phase ammonolysis. Among them, the chloroacetic acid aqueous phase ammonolysis method is widely used in the industry. This method has the defects of high energy consumption for methanol and ammonium chloride recovery, large catalyst consumption, low yield, large amount of wastewater and difficult treatment. After decades of unremitting efforts, domestic production enterprises have not been effectively solved, which seriously restricts the progress of green development of my country's glycine industry; and domestic glycine enterprises in the chloroacetic acid alcohol phase ammonolysis method are all in the research and development stage, and have not achieved real industrial application.

[0003] Chinese patent document CN109206329A discloses a method for preparing glycine. The process uses alcohol as a solvent and a large amount of iodide as an activating agent. First, chloroacetic acid is activated by heating to form iodoacetic acid and solid ammonium chloride is precipitated. Then, an alcohol solution of iodoacetic acid is obtained by filtration. Then, a urotropine catalyst is added to the alcohol solution of iodoacetic acid, and heating and ammonia gas are passed to perform an amination reaction. After the reaction is completed, centrifugation is performed to obtain an alcohol solution of glycine and iodide (containing the catalyst). The alcohol solution of iodide (containing the catalyst) can be recycled.

[0004] Although this method is different from most chloroacetic acid alcohol phase ammonolysis methods, it still has the following problems: (1) The reaction of chloroacetic acid and methanol to produce methyl chloroacetate is difficult to avoid. Methyl chloroacetate is easily produced as a by-product during the contact between the intermediate filtrate and chloroacetic acid, the material transfer process, and the reaction process. The accumulation of this oily substance will greatly reduce the catalytic effect of urotropine and affect the normal circulation of the system. The yield of the iodide-containing alcohol solution (including the catalyst) drops significantly after about 10 batches, the viscosity of the filtrate increases, and the crystal particles become smaller, making centrifugation difficult. (2) A large amount of expensive iodine reagent is used, and the recovery loss of the iodine reagent accounts for a large part of the production cost, which has no industrial application value. Summary of the invention

[0005] The technical problem to be solved by the utility model is to provide a device for producing glycine by an iodine catalysis method, which utilizes a two-step chemical reaction and a solubility difference to realize efficient separation of glycine crystals and ammonium chloride crystals, and the filtrate can be recycled, thereby greatly reducing the consumption of hexamethylenetetramine and steam, completely realizing clean production, and having industrial application value.

[0006] In order to solve the above technical problems, the present invention provides a device for producing glycine by iodine catalysis. To achieve the purpose of the present invention, the present invention adopts the above device, including the following equipment and pipelines (see attached Figure 1 ):

[0007] It mainly includes sub-units such as chloride synthesis, glycine synthesis, and methanol recovery.

[0008] The chloride synthesizer is mainly composed of a chloride synthesis reactor, a chloride centrifuge, a filtrate A receiving tank, and a filtrate A transfer pump. The large cover of the chloride synthesis reactor is connected with a methanol pipeline, an ammonium chloroacetate solid feeding pipeline, a glycine filtrate concentrate pipeline, and an iodine catalyst addition pipeline, and the bottom of the reactor is connected with a chloride centrifuge; the upper part of the chloride centrifuge is connected with a washing methanol pipeline, a nitrogen pipeline, and a venting pipeline, and the lower part is connected with a chloride filtrate pipeline and a filtrate receiving tank A.

[0009] The glycine synthesizer is mainly composed of a glycine synthesizer, a glycine centrifuge, a filtrate B receiving tank, and a filtrate B transfer pump. The large cover of the glycine synthesizer is connected with an ammonia pipeline, a urotropine pipeline, and a chloride filtrate pipeline (the filtrate receiving tank A is connected to the glycine synthesizer via the filtrate A transfer pump), the cylinder is connected with -5℃ chilled brine inlet and return pipes, and the bottom of the kettle is connected to the glycine centrifuge; the upper part of the glycine centrifuge is connected with a washing methanol pipeline, a nitrogen pipeline, and a venting pipeline, and the lower part is connected with a glycine filtrate pipeline and a filtrate receiving tank B.

[0010] The methanol recovery sub-unit is mainly composed of a methanol evaporator, a methanol heater, a forced circulation pump, a primary condenser, a secondary condenser, a methanol receiving tank, a methanol transfer pump, a vacuum unit, etc. The methanol evaporator, the methanol heater, the forced circulation pump, etc. constitute a liquid material circulation system. The filtrate receiving tank B is connected to the methanol recovery liquid phase circulation pipe through the filtrate A transfer pump. The gas phase pipe port on the upper part of the methanol evaporator is connected to the primary condenser, the secondary condenser, and the vacuum unit in sequence. The liquid phase pipe port on the side of the methanol evaporator is connected to the pipe port on the upper pipe side of the methanol heater. The lower pipe port of the methanol evaporator is connected to the inlet of the forced circulation pump, and the outlet of the forced circulation pump is connected to the pipe port on the bottom pipe side of the methanol heater. The liquid phase discharge port of the primary condenser and the liquid phase discharge port of the secondary condenser are both connected to the methanol receiving tank, and the methanol receiving tank is connected to the methanol transfer pump.

[0011] In view of the above-mentioned device, the utility model provides a process for producing glycine by iodine catalysis, a process for producing glycine by iodine catalysis, which adopts alternating synthesis and separation of chloride and glycine, such as chloride synthesis and separation, glycine synthesis and separation, chloride synthesis and separation, glycine synthesis and separation...; the filtrate A after chloride separation is used as the raw material for glycine synthesis, and the filtrate B after glycine separation is used as the raw material for chloride synthesis, and the two-step chemical reaction realizes the efficient separation of the two substances. It mainly includes the following steps:

[0012] A. reacting ammonium chloroacetate with an alcohol solution of iodide under heating conditions to generate ammonium iodoacetate and chloride. After the reaction is completed, washing the material with an alcohol solution and separating chloride crystals by centrifugation to obtain an alcohol solution of ammonium iodoacetate;

[0013] B. Add an appropriate amount of alcohol solution and a catalyst to the alcohol solution of ammonium iodoacetate, and introduce ammonia gas. After the reaction is completed, wash the material with the alcohol solution and separate the glycine crystal product by centrifugation, and at the same time obtain an alcohol solution containing the catalyst and iodide.

[0014] C. Further, reacting ammonium chloroacetate with the alcohol solution containing the catalyst and iodide obtained in step B under heating conditions to generate ammonium iodoacetate and chloride. After the reaction is completed, washing the material with the alcohol solution and separating the chloride crystals by centrifugation to obtain an alcohol solution containing the catalyst and ammonium iodoacetate;

[0015] D. To ensure the normal application of the centrifugal filtrate in step A and step B, obtain qualified glycine products and prevent the loss of the catalyst urotropine, after the chloride is separated in step A, the alcohol solution containing the catalyst and ammonium iodoacetate, which is left over from the chloride and glycine crystal washing, needs to be distilled under reduced pressure to recover a portion of the alcohol (the end point of the alcohol recovered by reduced pressure distillation (taking methanol as an example) is: 80-100% of the total volume of chloride washing alcohol + glycine washing alcohol + alcohol added to the glycine synthesis reactor).

[0016] E. After adding appropriate amount of alcohol and catalyst to the concentrated solution (containing alcohol, catalyst, ammonium iodoacetate), ammonia gas is introduced. After the reaction is completed, the material is washed with alcohol solution and glycine crystals are separated by centrifugation. At the same time, an alcohol solution containing catalyst and iodide is obtained.

[0017] The amount of alcohol added in step B and step E is preferably to ensure that NH4Cl is completely dissolved, and the Cl- content in the solution is controlled to be below 0.5%, while avoiding precipitation of urotropine.

[0018] The catalyst added in step B and step E is 1-10% of the alcohol solution of ammonium iodoacetate in step B or the concentrated solution in step E.

[0019] Repeat the steps ABCDECDE... (the repeated cycle means that after performing steps ABC, steps CDE are repeatedly cycled, and glycine product is obtained in the multi-stage cycle process).

[0020] The technical solution of the present invention is further improved in that: in step A, the reaction raw material is ammonium chloroacetate instead of chloroacetic acid, the mass ratio of ammonium chloroacetate to iodide is 1:1.8-2.5, and the mass fraction of ammonium iodoacetate in the alcohol solution of ammonium iodoacetate is 20-33%.

[0021] The further improvement of the technical solution of the present invention is that in step B, the catalyst is urotropine, and the mass ratio of ammonium chloroacetate to the catalyst is 1:1.17-2.35.

[0022] A further improvement of the technical solution of the present invention is that the alcohol solution of ammonium iodoacetate in step B can dissolve the catalyst and then pass ammonia to react, thereby eliminating the process of dripping the liquid raw material into the catalyst solution.

[0023] A further improvement of the technical solution of the present invention is that the reaction temperature of step A is 50-70° C., the reaction time is 30-150 minutes, and after the reaction is completed, the temperature is lowered to below 20° C. and then centrifuged.

[0024] The further improvement of the technical solution of the present invention is that the reaction temperature of step B is 45-65° C., the reaction time is 120-240 minutes, ammonia is passed to keep the pH of the reaction system at 7-9, and centrifugation is performed directly after the reaction is completed.

[0025] A further improvement of the technical solution of the present invention is that the alcohol solution of ammonium iodoacetate obtained in step A can be immediately put into step B, or can be stored separately for a period of time before entering step B.

[0026] The alcohol solution used in the above steps A, B, C, D and E is selected from the alcohol solution of C1-C4.

[0027] In the step C, the mass ratio of ammonium chloroacetate to the alcohol solution containing the catalyst and iodide obtained in the step B is 1:10-1:13.

[0028] The reaction conditions of step C are the same as those of step A, specifically, the reaction temperature is 50-70° C., the reaction time is 30-150 minutes, and after the reaction is completed, the temperature is lowered to below 20° C. and then centrifuged.

[0029] The reaction conditions of step E are the same as those of step B, specifically, the reaction temperature is 45-65° C., the reaction time is 120-240 minutes, ammonia is passed to keep the pH of the reaction system at 7-9, and centrifugation is performed directly after the reaction is completed.

[0030] Due to the adoption of the above technical solution, the technical progress achieved by the utility model is:

[0031] In the device for producing glycine by an iodine catalysis method of the present invention, the side reaction of ammonium iodoacetate or ammonium chloroacetate with alcohol and the catalyst urotropine is almost non-existent, and a series of key factors affecting product quality, filtrate circulation and urotropine consumption in step A and step B, such as too long reaction time, too long invalid operation time, over-temperature, high pH and the like, do not need to be considered.

[0032] The filtrate of step A and step B in the utility model can be repeatedly applied for more than 100 times, and the ammonium chloride and glycine crystals will not be difficult to filter due to the increase in the number of cycles. The present invention solves the problems of difficulty and high energy consumption in separating the mixture of glycine and ammonium chloride in the traditional aqueous phase method, and also solves the possibility of the presence of methyl chloroacetate in the previous alcohol phase method, thoroughly solves the problem of efficient separation of glycine and ammonium chloride and difficulty in recycling urotropine, and further simplifies the process operation.

[0033] Compared with the high-temperature reaction of the aqueous phase method and the narrow temperature and pH control range of the previous iodine method process, the present invention adds iodide as an intermediate reaction, the reaction rate is faster, and the reaction can be thorough within a wider temperature and pH range to obtain a glycine product with a main content of ≥98.5%, a chloride content of ≤0.3% and suitable for glyphosate synthesis.

[0034] The alcohol solution containing the iodide of the catalyst obtained in step B of the utility model can be directly used in the next step of the reaction cycle, without generating waste liquid, the process operation is simple and the production cost is reduced, the catalyst and the alcohol solution are circulated synchronously, the amount of catalyst added in the circulating batch is only 0.1% for the first time, and the amount of hexamethylenetetramine used is greatly reduced.

[0035] The utility model has strong operability, lower reagent input, and greatly reduced production costs. Different from the two-step reaction, the utility model can react in one kettle, reducing the complex management and organizational problems caused by the two-step process control, and is more suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural diagram of the device for glycine synthesis. Among them, 1-chloride synthesis reactor; 2-chloride centrifuge; 3-filtrate receiving tank A; 4-filtrate A transfer pump; 5-glycine synthesis reactor; 6-glycine centrifuge; 7-filtrate receiving tank B; 8-filtrate B transfer pump; 9-methanol evaporation tank; 10-methanol heater; 11-forced circulation pump; 12-primary condenser; 13-secondary condenser; 14-methanol receiving tank; 15-methanol transfer pump; 16-vacuum unit. DETAILED DESCRIPTION

[0037] Example 1

[0038] A device for producing glycine by an iodine catalytic method mainly comprises sub-devices such as chloride synthesis, glycine synthesis, and methanol recovery. The chloride synthesis sub-device mainly consists of a chloride synthesis kettle, a chloride centrifuge, a filtrate A receiving tank, and a filtrate A transfer pump. The large cover of the chloride synthesis kettle is connected with a methanol pipeline, an ammonium chloroacetate solid feeding pipeline, a glycine filtrate concentrate pipeline, and an iodine catalyst addition pipeline, and the bottom of the kettle is connected with a chloride centrifuge; the upper part of the chloride centrifuge is connected with a washing methanol pipeline, a nitrogen pipeline (not shown), and a venting pipeline (not shown), and the lower part is connected with a chloride filtrate pipeline and a filtrate receiving tank A. The glycine synthesis sub-device mainly consists of a glycine synthesis kettle, a glycine centrifuge, a filtrate B receiving tank, and a filtrate B transfer pump. The large cover of the glycine synthesis reactor is connected with an ammonia pipeline (not shown), a urotropine pipeline, and a chloride filtrate pipeline (the filtrate receiving tank A is connected to the glycine synthesis reactor via the filtrate A transfer pump), the cylinder of the reactor is connected with a -5°C chilled brine inlet and return pipe, and the bottom of the reactor is connected with a glycine centrifuge; the upper part of the glycine centrifuge is connected with a washing methanol pipeline, a nitrogen pipeline (not shown), and a venting pipeline (not shown), and the lower part is connected with a glycine filtrate pipeline and a filtrate receiving tank B. The methanol recovery sub-device is mainly composed of a methanol evaporator, a methanol heater, a forced circulation pump, a primary condenser, a secondary condenser, a methanol receiving tank, a methanol transfer pump, a vacuum unit, etc. The methanol evaporator, the methanol heater, the forced circulation pump, etc. constitute a liquid phase material circulation system. The filtrate receiving tank B is connected to the methanol recovery liquid phase circulation pipe through the filtrate A transfer pump, the upper gas phase pipe port of the methanol evaporator is connected to the primary condenser, the secondary condenser, and the vacuum unit in sequence, the side liquid phase pipe port of the methanol evaporator is connected to the upper pipe port of the methanol heater, the lower pipe port of the methanol evaporator is connected to the inlet of the forced circulation pump, and the outlet of the forced circulation pump is connected to the bottom pipe port of the methanol heater. The liquid phase discharge port of the primary condenser and the liquid phase discharge port of the secondary condenser are both connected to the methanol receiving tank, and the methanol receiving tank is connected to the methanol transfer pump.

[0039] Example 2

[0040] The following test was carried out according to the device of Example 1:

[0041] First cycle: add 6000L of anhydrous methanol, 1000kg of potassium iodide (6kmol) solid, and 590kg of solid ammonium chloroacetate into K8000L salting-out kettle A (referring to the chloride synthesis kettle), stir thoroughly, heat to 50℃ with hot water and keep warm for 4h; cool to 20℃ and then centrifuge, wash the material with methanol twice (150L each time), centrifuge, and obtain 237.2kg of potassium chloride dry powder solid after centrifugation; obtain filtrate after centrifugation, and transfer the filtrate to glycine synthesis kettle B through filtrate A transfer pump.

[0042] Add 1500L of anhydrous methanol and 250kg of urotropine to the K8000L glycine synthesis reactor B; heat to 44°C and then naturally heat to 47-50°C, and start passing ammonia at a rate of 150kg / h; pause after passing ammonia for 10 minutes, and continue passing ammonia at a rate of 150kg / h, with an ammonia amount of 175kg, pH=7.5-8; pass ammonia for 1h, and keep warm for 3h after the end of ammonia passing; centrifuge directly after the end of insulation, wash the material with 450L of methanol, centrifuge, and dry to obtain 227.2kg of glycine dry powder (main content 92.9%, chloride ion content 0.48%), with a glycine synthesis yield of 54.8%, and the filtrate obtained after centrifugation is temporarily stored in the filtrate receiving tank B for the next step.

[0043] Methanol recovery: first add 2 ml of the filtrate in the filtrate receiving tank B into the methanol evaporator (single-effect evaporator). 3 The filtrate was circulated by the forced circulation pump, 50°C hot water was introduced into the heater, the vacuum degree was maintained at 0.08Mpa, and methanol was slowly evaporated to recover; the feed flow rate was 6m 3 / h continues to feed the methanol evaporator (the feed here refers to the filtrate receiving tank B), at 3.75m 3 / h is produced into the salting out kettle A, and the methanol condensate enters the methanol receiving tank for temporary storage. In this concentration step, the concentration amount = 150*2+1500+450=2250L.

[0044] Second cycle: add 580kg of potassium iodide (3.5kmol) solid and 590kg of solid ammonium chloroacetate into K8000L salting-out kettle A, stir thoroughly, heat to 50℃ and keep warm for 4h; cool to 20℃ and centrifuge, wash with methanol twice (150L each time), centrifuge, and obtain 247.1kg of ammonium chloride dry powder (nitrogen content 19.7%) after centrifugation; obtain filtrate after centrifugation, and transfer the filtrate to glycine synthesis kettle B through filtrate A transfer pump.

[0045] 1500L of anhydrous methanol and 25kg of urotropine were added to the K8000L glycine synthesis reactor (i.e., glycine synthesis reactor B); the temperature was raised to 44°C and then naturally raised to 47-50°C, and ammonia was introduced at a rate of 150kg / h; the introduction of ammonia was paused after 10 minutes, and ammonia was continued at a rate of 150kg / h, with an ammonia amount of 175kg, and pH = 7.5-8; the ammonia introduction time was 60min, and the temperature was kept warm for 180min after the ammonia introduction was completed; after the insulation was completed, the material was directly centrifuged, washed with 450L of methanol, centrifuged, and dried to obtain 426.9kg of glycine dry powder (main content 93.5%, chloride ion content 0.91%), and the filtrate B was temporarily stored for the next step, and the glycine synthesis yield was 103.7%.

[0046] ...repeatedly cycle up to 20 batches (the repeated cycles here refer to the chloride synthesis, glycine synthesis, and methanol recovery steps.)

Claims

1. An apparatus for producing glycine by iodine catalysis, characterized in that: The chloride synthesis reactor (1) is connected to the filtrate receiving tank A (3) via the chloride centrifuge (2); The filtrate receiving tank A (3) is connected to the glycine synthesis reactor (5) via the filtrate A transfer pump (4); The glycine synthesis reactor (5) is connected to the glycine centrifuge (6); The glycine centrifuge (6) is connected to the filtrate receiving tank B (7); The filtrate receiving tank B (7) is connected to the methanol evaporation tank (9) via the filtrate B transfer pump (8).

2. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The chloride synthesis reactor (1) is connected with a methanol pipeline, an ammonium chloroacetate solid feeding pipeline and an iodine catalyst adding pipeline; the upper part of the chloride centrifuge (2) is connected with a washing methanol pipeline, a nitrogen pipeline and a venting pipeline.

3. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The glycine synthesis reactor (5) is connected with an ammonia pipeline and a urotropine pipeline; The upper part of the glycine centrifuge (6) is connected with a washing methanol pipeline, a nitrogen pipeline, and a venting pipeline.

4. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The gas phase pipe port at the upper part of the methanol evaporation tank (9) is connected to the primary condenser (12), the secondary condenser (13), and the vacuum unit (16) in sequence.

5. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The liquid phase discharge port of the first condenser (12) and the liquid phase discharge port of the second condenser (13) are both connected to the methanol receiving tank (14), and the methanol receiving tank (14) is connected to the methanol transfer pump (15).

6. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The lower pipe opening of the methanol evaporator (9) is connected to the inlet of the forced circulation pump (11), the outlet of the forced circulation pump (11) is connected to the bottom pipe opening of the methanol heater (10), and the side liquid phase pipe opening of the methanol evaporator (9) is connected to the upper pipe opening of the methanol heater (10).

7. The device for producing glycine by iodine catalysis according to claim 1, characterized in that: The outlet of the forced circulation pump (11) is also connected to the inlet of the chloride synthesis reactor (1).

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