CN105985251B - A kind of amino acids process for cleanly preparing such as iminodiacetic acid - Google Patents

Abstract

The invention relates to a clean production method of amino acids such as iminodiacetic acid. Using cheap milk of lime to carry out alkaline hydrolysis and deamination of amino nitriles, the crude iminodiacetic acid calcium salt can be obtained. The obtained iminodiacetic acid calcium salt crude product can be suspended in water or mother liquor, acidified by adding sulfuric acid or other inorganic acids, and filtered out the inorganic calcium salt filter cake with low water solubility. The filtrate is cooled and crystallized, and the iminodiacetic acid solid can be obtained by separation, and the crystallization mother liquor is used for the next batch of acidification reactions. When acidifying with sulfuric acid, the by-product ammonia water and carbon dioxide in the flue gas during alkaline hydrolysis can be further used to convert gypsum into calcium carbonate and ammonium sulfate, and directly generate compound fertilizer; calcium carbonate can also be separated to concentrate ammonium sulfate crystals; Calcium can be sold as a by-product or thermally decomposed quicklime raw material. The new process can realize the full utilization of resources, higher reaction selectivity, reduce the generation of colored by-products, and avoid the process of concentration and removal of waste salt such as sodium sulfate and sodium chloride and the waste water treatment process. Concentration can greatly reduce the amount of decolorizing agent and save energy. Significant reduction in consumption and significant reduction in production costs.

Description

A clean production process for amino acids such as iminodiacetic acid

technical field

The invention relates to a clean production process for amino acids such as iminodiacetic acid, and belongs to the technical fields of pesticides, fertilizers and fine chemicals.

Background technique

Iminodiacetic acid, CAS No. 142-73-4, alias iminodiacetic acid, N-(carboxymethyl) glycine, aminodiacetic acid, referred to as IDA. Iminodiacetic acid is mainly used as an intermediate in the synthesis of glyphosate and other pesticides, and can also be used as a phosphorus-releasing organic double-effect fertilizer, a raw material for ion exchange resins, rubber, electroplating, and food additives.

Iminodiacetic acid has the following synthetic routes:

1. Chloroacetic acid method Chloroacetic acid reacts with ammonia water or sodium hydroxide to produce sodium chloroacetate, then reacts with hydrazine hydrate to form hydrazinodiacetic acid, and then acidifies with hydrochloric acid under the action of sodium nitrite to form iminodiacetic acid hydrochloride Salt, standing to crystallize, suction filtration, pickling, dissolving it in hot water, adding sodium hydroxide solution for neutralization, and then generating iminodiacetic acid. This method has low yield, large amount of waste water, cumbersome steps and high cost of raw materials, so it has been eliminated.

2. Diethanolamine method The diethanolamine method is a synthetic process developed in the 1990s in the world. Diethanolamine is used as the main raw material. In the presence of Cu-Ni alloy catalyst and sodium hydroxide, it is passed through high temperature (170°C) and pressure (0.8 Mpa) deamination to generate sodium iminodiacetic acid, and then acidify to synthesize iminodiacetic acid. The raw material diethanolamine of this method is greatly affected by the price of crude oil, and high-concentration saline wastewater is difficult to treat. This process has been basically replaced by the hydrocyanic acid method.

3. Hydrocyanic acid method This method is the mainstream production method at home and abroad. US Patent No. 5,187,301 reports the preparation of iminodiacetonitrile with hydroxyacetonitrile, and Chinese patent CN1609112A reports the synthesis of iminodiacetic acid with disodium salt of iminodiacetic acid. The iminodiacetonitrile intermediate synthesized by hydrocyanic acid is hydrolyzed with sodium hydroxide, acidified, decolorized, crystallized, and separated to obtain iminodiacetic acid. This method has the problems of loss of alkali hydrolysis yield and easy production of colored substances. The yield of diacid is only about 90%. A large amount of diacid wastewater containing salt is concentrated and desalinated, and the method of regeneration of evaporative condensate is used. The energy consumption is high, and the salt The quality is poor and it is difficult to use. Although the method for the synthesis of iminodiacetic acid by the acid hydrolysis of iminodiacetonitrile that we developed has reduced the use of by-products and sodium hydroxide, avoided production waste water, and obtained valuable ammonium chloride, there are complicated refining processes and solid The number of times of liquid separation is large, and the disadvantage of large investment. Therefore, it is still valuable to explore the clean production process of amino acid with simple process, low investment and low production cost.

Contents of the invention

The object of the present invention is to provide a clean production process for preparing iminodiacetic acid, glycine and other amino acids by alkaline hydrolysis of amino nitriles.

In our research, we found that there are decomposition and polymerization problems in the process of alkali hydrolysis of aminonitriles with sodium hydroxide, which affects the yield and product appearance. Its reason is because sodium hydroxide solution alkaline is too strong, even control temperature also can't effectively suppress its decomposition raw material to generate glycolic acid and glycine and the side reaction that formaldehyde and hydrocyanic acid polymerize and generate colored substances.

The invention provides a method of alkaline hydrolysis of iminodiacetonitrile by using calcium hydroxide, which has a lower alkalinity and solubility than sodium hydroxide solution, and the cost is only about one-fifth of sodium hydroxide, to obtain water-soluble Smaller calcium iminodiacetic acid can be separated or directly acidified with inorganic acids such as sulfuric acid to separate the low-water-soluble inorganic calcium salt filter cake, and the method of cooling and crystallizing to obtain iminodiacetic acid.

Specifically, the present invention provides a method for clean production of amino acids such as iminodiacetic acid, the method comprising the following steps:

(1) Add iminodiacetonitrile and/or aminoacetonitrile-containing products, raw materials or mother liquor to milk of lime, react for 0.5-3 hours, deamination and control the end point of deamination when the pH of ammonia-containing water vapor is 8-9, after Filtration, washing, separation of iminodiacetic acid calcium crude product filter cake, alkaline hydrolysis mother liquor and washing water as quicklime water recycling or direct acidification acidification crystallization;

(2) Add the crude calcium iminodiacetic acid filter cake obtained in step (1) into water or the crystallization mother liquor of iminodiacetic acid to stir and disperse, add sulfuric acid or other inorganic acids to acidify, and filter out the inorganic calcium salt with low water solubility. cake, wash the filter cake, and the washing liquid is combined for the next batch of materials for diluting concentrated sulfuric acid or other inorganic acids, and the filtrate is a solution containing iminodiacetic acid;

(3) Cool the filtrate obtained in step (2), crystallize under stirring, filter and wash, the resulting filter cake is iminodiacetic acid crystals, and the crystallization mother liquor is recycled and used in step (2).

2. The method according to claim 1, wherein,

The crude calcium iminodiacetate is acidified with sulfuric acid, and the gypsum by-product obtained by acidification with sulfuric acid is suspended in the by-product ammonia water and passed through carbon dioxide and ammonia water generated in the alkaline hydrolysis section for conversion. After the reaction is completed, filter and wash, and the obtained solid is calcium carbonate; Or concentrate and crystallize to separate ammonium sulfate, and continue to apply the mother liquor; the generated gypsum or the further converted calcium carbonate-ammonium sulfate reaction mixture can also be directly used as a compound fertilizer raw material without separation.

3. The method according to claim 1, wherein, in step (1), the mass ratio of iminodiacetonitrile or aminoacetonitrile to calcium oxide is 1:0.1-1.0, and the reaction temperature is 50-90°C; the reaction liquid The deamination temperature is controlled at 70-105°C.

4. The method according to claim 1, wherein, in step (1), the lime can be digested with clean water, or with an aqueous solution containing sodium sulfate and potassium sulfate, or the previous batch of alkaline hydrolysis mother liquor.

5. The method according to any one of claims 1-4, wherein, in step (2), the molar ratio of the total acid amount of sulfuric acid or other inorganic acids to the iminodiacetic acid in the crude product of calcium iminodiacetate The acidification temperature is 0.5-3:1, the acidification end point pH is 2, the acidification temperature is 50-105°C, and the acidification time is 0.5 h-5 h. 6. The method according to any one of claims 1-5, wherein, in step (2), the amount of sulfuric acid added to the gypsum washing water is preferably 30%-50% of the amount required for the following batch of acidification reactions. The temperature is controlled above 60°C.

7. The method according to claim 2, wherein the reaction temperature is 30-70°C, and the reaction time is 0.5-5h.

8. According to the method described in claim 1, the material after alkaline hydrolysis deamination can be directly acidified without separation, and after the insoluble inorganic calcium salt is separated, the amino acid product is crystallized, and the mother liquor is used mechanically.

9. According to the method according to claim 1, the end point of the acidification of the filtrate after the calcium iminodiacetate solid is separated is the isoelectric point of the corresponding amino acid.

The preparation of iminodiacetic acid from iminodiacetonitrile is taken as an example below to describe the present invention in detail.

In step (1), the reaction chemical formula of the alkali hydrolysis of iminodiacetonitrile with calcium hydroxide is as follows:

In the alkali hydrolysis process, the order of adding raw materials, reaction temperature, etc. have a direct impact on the composition of the alkali hydrolysis product, and how to optimize the reaction conditions is the key to realizing the alkali hydrolysis.

The heat energy released by the reaction of quicklime and water to generate calcium hydroxide can make the temperature of the whole system reach the temperature required for the reaction at 50-60°C, and then add iminodiacetonitrile in batches, and alkali hydrolysis for 0.5-3 hours can make the liquid in the solution The iminodiacetonitrile reacted completely. If lime and iminodiacetonitrile are added step by step according to the method of other patents (publication number: CN101619077A), the content of impurities such as nitrilotriacetic acid and glycine in the product will increase significantly, wherein: the mass fraction of nitrilotriacetic acid is determined by this The non-detection of the inventive process was raised to 3.2%, and the mass fraction of glycine was raised to 0.09% by the non-detection of the inventive process. The results show that the addition of lime and iminodiacetonitrile step by step, due to the strong alkalinity of the reaction solution, high calcium content and other ionic effects, the reaction between lime and water is inhibited, resulting in a longer alkaline hydrolysis time (4-6 h). , the by-products increase. Follow-up studies have found that if a small amount of ammonia remains in the reaction solution, the end point of deamination is controlled at the pH of the ammonia-containing water vapor at 8-9, so that the impurity nitrogen triacetate calcium glycinate can be dissolved in the mother liquor, and most of the imino diacetate Calcium acetate is precipitated in the form of solids; if according to the method of other patents (public number: CN101619077A), the near neutrality of steam condensed water can be used as the deamination end point, which will cause the mass fraction of nitrilotriacetic acid in the product to be changed by the unspecified process of the present invention. Detection increased to 0.7%, and the mass fraction of glycine was increased to 0.09% by the non-detection of the process of the present invention. The results show that the deamination end point is controlled at the pH of the ammonia-containing water vapor at 8-9, which can avoid the precipitation of calcium nitrilotriacetate and calcium glycinate impurities together with calcium iminodiacetate, which is conducive to the application of the mother liquor in the next step.

We found that the presence of sulfate-containing substances such as sodium sulfate and potassium sulfate in lime milk can promote the alkali hydrolysis and deamination speed of iminodiacetonitrile.

Further studies have found that the solubility of calcium iminodiacetate does not change much with temperature, and it can be filtered hot without cooling and then filtered.

For step (2), we found that the molar ratio of the total acid amount of sulfuric acid or other inorganic acids added to the iminodiacetic acid in the crude calcium iminodiacetic acid can be controlled at 0.5-3:1. When sulfuric acid is used for acidification, the sulfuric acid hydration heat and reaction heat can evaporate and condense part of the water vapor, which is convenient for temperature adjustment and water balance adjustment. At this temperature, acidification for 0.5-5 hours can make all the calcium iminodiacetate completely into iminodiacetic acid. The specific chemical reaction formula is as follows:

The crude gypsum obtained by filtration contains about 20% iminodiacetic acid. In order to avoid washing the gypsum with a large amount of hot water, the concentration load will be increased and the water balance will be affected. The gypsum can be washed with hot acid water that adds 30%-50% of the mineral acid used in the next batch of reaction in the washing water or mechanical washing water, and the separated washing liquid is then added with the remaining inorganic acid for the next batch of acidification reaction. The washing temperature is controlled above 50°C. On the one hand, it can increase the solubility of iminodiacetic acid in water. On the other hand, when sulfuric acid is used for acidification, it can avoid the reaction of gypsum and sulfuric acid to form calcium hydrogen sulfate precipitation.

For step (3), the study found that the solubility of iminodiacetic acid decreases with the decrease of temperature, for example, at 20°C, its solubility in water is 2.6 g, at 50°C it is 9.73 g, at 80°C it is 23.8 g, 50 g at 100°C. Considering energy saving and mother liquor can be applied mechanically, we chose to acidify at boiling temperature to obtain iminodiacetic acid-gypsum system and heat filter, and cool the hot filtrate to below 50°C with cooling water, and stir and crystallize at this temperature for at least 2 h In the above, it is easy to filter with sufficient crystallization, and the crystals of iminodiacetic acid can be obtained by filtering and washing.

The obtained crystallization filtrate can be applied mechanically to the next batch of acidification reaction. After applying the filtrate for many times, if the color is darker, it can be decolorized with activated carbon and continue to be used.

The method of other patents (CN101619077A) uses the mixed acidification of concentrated sulfuric acid and hydrochloric acid to separate iminodiacetic acid from gypsum in the form of hydrochloride. Not only need a large amount of concentrated mother liquor, frequent decolorization, glycine and nitrilotriacetic acid contained in the iminodiacetic acid hydrochloride solution will cause the decline of the yield and quality of diglyphosate, and reduce the number of times of applying the mother liquor.

The present invention adopts the scheme of temperature-variable crystallization and mother liquor, which avoids a large amount of concentrated mother liquor and basically avoids decolorization compared with the existing technology, simplifies the process steps, can save investment, can greatly reduce energy consumption, significantly reduce production costs, and realizes cleanness Production. .

Because a large amount of ammonia gas is produced by-product in the alkali hydrolysis process of iminodiacetonitrile, this part of ammonia gas can be recycled as the raw material of the front or other products. The gypsum produced by acidifying calcium iminodiacetic acid with sulfuric acid can be used as raw material for cement and gypsum board, and can also be used for improvement of saline-alkali land or acidic soil nearby. In order to solve the problem of the outlet, storage and transportation of by-product ammonia water, it can be converted into calcium carbonate and ammonium sulfate as raw materials for compound fertilizers to meet the needs of a large amount of acidic soil improvement and emission reduction. For this reason, we have developed a method for producing calcium carbonate, ammonium sulfate and calcium carbonate-ammonium sulfate compound fertilizer by using the by-product ammonia and gypsum in the process of producing iminodiacetic acid: after washing the sulfuric acid in step (2), The crude gypsum is stirred with an appropriate amount of water, passed through the flue gas rich in carbon dioxide and ammonia gas produced in the alkaline hydrolysis section, reacted at 45-55°C for 2 hours, filtered, and washed to obtain calcium carbonate solid, which can be used as a commercial product after drying. Ammonium sulfate crystals can be separated by concentrating or cooling the filtrate, and the mother liquor can be used mechanically; the reaction mixture can also be used without separation to produce calcium carbonate-ammonium sulfate compound fertilizer.

In summary, the new process achieves the goal of rapid alkaline hydrolysis of lime milk and high yield to prepare calcium iminodiacetate. In the process, we also cleverly utilized the heat of hydration of lime and sulfuric acid, as well as the heat of reaction released during the acidification of sulfuric acid. The heating and concentration of the system greatly reduces energy consumption, and avoids the problems of mother liquor concentration and desalination through the by-product of gypsum; through mechanical application and variable temperature crystallization strategy, the energy consumption of iminodiacetic acid crystallization is greatly reduced, and the mother liquor can be put back The system again avoids the energy consumption of concentration and the loss of diacid in the traditional process; the by-product gypsum can be directly sold as a by-product; it can also be further converted into raw materials or fertilizers by using the excess carbon dioxide and the by-product ammonia in the alkaline hydrolysis section.

Therefore, the new process fundamentally overcomes the shortcomings of the existing process, eliminates the link of concentration and desalination, reduces the number of activated carbon decolorization, saves a lot of heat and cold energy, improves the product yield, and suppresses the formation of by-products. Reached the goal of significant energy saving and consumption reduction and clean production.

Detailed ways

Example 1 Preparation of calcium iminodiacetate by hydrolyzing iminodiacetonitrile with milk of lime

Lime (31.4 g, 98%, 0.55 mol) was added to water (200 g), and stirred for 15 min. Keep the temperature of the solution at about 50°C, add iminodiacetonitrile (50 g, 95%, 0.5 mol) in portions, and complete the addition in about half an hour. Stir at 50-55°C for 0.5-1 h, raise the temperature to about 90-100°C, deamination under reduced pressure, and replenish water in due time. When the pH of the evaporated water vapor is 8-9, stop the deamination. The solution was filtered and washed.

The crude product of calcium iminodiacetic acid was obtained (113 g, containing iminodiacetic acid: 58 g, no other impurities were found on ¹ H-NMR), the combined washings of the filtrate (containing iminodiacetic acid: 5.2 g), iminodiacetic acid Calcium acetate total yield is 95.0%.

Example 2 Calcium iminodiacetate was prepared by hydrolyzing iminodiacetonitrile with milk of lime, and the mother liquor was applied mechanically

Put lime (31.4 g, 98%, 0.55 mol) into water (60 g), stir and react for 15 min, and then add the mother liquor from the previous batch of calcium salt separation. Keep the temperature of the solution at about 50°C, add iminodiacetonitrile (50 g, 95%, 0.5 mol) in portions, and complete the addition in about half an hour. Stir at 50-55°C for 0.5-1 h, raise the temperature to about 90-100°C, deamination under reduced pressure, and replenish water in due time. When the pH of the evaporated water vapor is 8-9, stop the deamination. The calcium iminodiacetic acid was filtered out, washed, washed with water and combined with mother liquor for the next batch of reactions.

The experimental results are as follows, the total yield of iminodiacetic acid in the crude product of 7 batches of reaction iminodiacetic acid calcium is 93.10%, the yield of IDA in the final mother liquor is 2.26%, and the total yield of 7 batches of reaction iminodiacetic acid is 95.50% .

Example 3 Patent (publication number: CN101619077A) method to prepare calcium iminodiacetate

Add 872 mL of water to the reactor, evacuate to 0.1 Mpa, raise the temperature to 45-50°C, add lime (70%, 143 g) and iminodiacetonitrile (95%, 151 g) into the water several times evenly, each Add once every 5 minutes, finish adding in 3 hours, keep warm for 1 hour, then raise the temperature to 75°C, keep warm for 2 hours, then raise the temperature to 100°C, keep warm for reaction, stop the reaction when the pH of the water vapor is 7, cool, filter, The filtrate and filter cake were collected separately.

The crude product of calcium iminodiacetic acid (117 g, containing iminodiacetic acid: 58.8 g, impurities: nitrilotriacetic acid: 3.8 g, glycine: 0.1 g) was obtained in the experiment, and the filtrate was combined with washing liquid (containing iminodiacetic acid: 3.53 g ), the total yield of iminodiacetic acid was 93.8%.

Compared with Example 1, this method prepares iminodiacetic acid calcium, and the reaction time is long, and contains impurities such as nitrilotriacetic acid, glycine in the product.

Example 4 Lime milk hydrolyzes iminodiacetonitrile, and the end point of deamination is controlled at the pH of water vapor = 7

Lime (31.4 g, 98%, 0.55 mol) was added to water (200 g), and stirred for 15 min. Keep the temperature of the solution at about 50°C, add iminodiacetonitrile (50 g, 95%, 0.5 mol) in portions, and complete the addition in about half an hour. Stir at 50-55°C for 0.5-1 h, heat up to about 90-100°C, remove ammonia under reduced pressure, and replenish water in due course, and stop deamination when the pH of the evaporated water vapor is 7. The solution was filtered and washed.

The crude product of calcium iminodiacetic acid (118 g, containing iminodiacetic acid: 60 g, nitrilotriacetic acid 0.8 g, glycine: 0.1 g) was obtained in the experiment, and the filtrate combined washing liquid (containing iminodiacetic acid: 3.0 g, nitrilotriacetic acid: 3.0 g, nitrilotriacetic acid: 0.1 g) Triacetic acid: 0.8 g, glycine: 0.5 g), and the total yield of iminodiacetic acid was 95.0%.

Compared with Example 1, if the deamination end point is controlled at the pH=7 of the water vapor, impurities such as nitrilotriacetic acid will be precipitated together with calcium iminodiacetate.

Example 5 Solubility of iminodiacetic acid calcium at different temperatures

We tested the solubility of calcium iminodiacetic acid in water at different temperatures, and the results showed that the solubility did not change much with temperature and was stable at about 1 g.

Example 6 The solubility of iminodiacetic acid at different temperatures

We tested the solubility of iminodiacetic acid in water at different temperatures, and the results showed that the solubility increased with the increase of temperature.

Example 7 Sulfuric acidification of calcium iminodiacetate

Add the crude calcium iminodiacetic acid (35 g, containing 20 g iminodiacetic acid) into water (100 g), add sulfuric acid (98%, 15.1 g) dropwise under stirring, keep at 95-100°C for 1 hour, concentrate, keep The total volume before filtration is about 125mL, filter while hot. The resulting filtrate and filter cake were tested separately.

The experimental results showed that the filtrate contained 14.5 g of iminodiacetic acid, and the yield was 72.5%; 5.5 g of iminodiacetic acid was entrained in the filter cake; the total reaction yield was greater than 99%.

Example 8 Washing crude gypsum with dilute sulfuric acid solution

Add sulfuric acid (98%, 5 g) into washing water (25 g), raise the temperature to 70°C, wash the filter cake in Example 7, filter, and wash the filter cake with water (5 g). The filtrate contained 5.4 g of iminodiacetic acid; the weight of the filter cake was 23.5 g after drying, the yield was greater than 99% based on CaSO ₄ ·0.5 H ₂ O, and the entrained iminodiacetic acid was less than 0.05 g.

Example 9 Preparation of iminodiacetic acid by cooling and crystallizing iminodiacetic acid solution

The filtrate (170 g, containing 14.5 g of iminodiacetic acid) obtained in Example 7 was stirred and cooled to room temperature, and crystallized at room temperature for 2 h, filtered, washed, washed with water and combined with the filtrate (157 g, containing iminodiacetic acid diacetic acid 3.5 g). The filter cake was dried, crushed and weighed to obtain 11.8 g of iminodiacetic acid with a content of 99.5%.

Example 10 Sulfuric acid acidifies calcium iminodiacetate, and after the filtrate is crystallized, it can be recycled

Add the crude calcium iminodiacetic acid (35 g, containing 20 g iminodiacetic acid) into water (100 g), add sulfuric acid (98%, 15.1 g) dropwise under stirring, keep the reaction at 95-100°C for 1 h, and concentrate the excess water , keep the total volume before filtration at about 125-150mL, and filter while hot. The filtrate was stirred and cooled down to room temperature, and crystallized at room temperature for 2 h, filtered, washed twice with water (15 g), the first washing was used to wash the crude gypsum, and the second washing was used as the first washing of the next batch of products. water. The product is dried, crushed and weighed. The crystallization mother liquor is used for the next batch of acidification reactions.

Add sulfuric acid (98%, 5 g) to the product washing water and clean water (20-25 g), raise the temperature to 70°C, wash the filter cake, filter, wash the filter cake twice with clean water (5 g), and wash water once Merge into the washing liquid, and use the 2 times of washing water as the 1 washing water of the next batch of gypsum. Combine the washing solution and clear water, and add the remaining sulfuric acid for the acidification of the next batch of reactions. The last batch of gypsum is washed with a large amount of hot water, and the washing liquid is combined into the crystallization mother liquor.

Add activated carbon (0.6 g) to the last iminodiacetic acid crystallization mother liquor (140 g, containing iminodiacetic acid: 10.89 g), heat up to 80°C, stir at this temperature for 1 h, cool, filter, and wash. The color of crystallization mother liquor can change from black to light brown. Concentrate most of the water and dry the resulting solid to obtain iminodiacetic acid (11.5 g, purity 95.1%). The activated carbon was washed several times with dilute hydrochloric acid solution, and it was detected that the washing solution contained 0.21 g of iminodiacetic acid.

Experimental result shows, 7 batches of acidification reactions iminodiacetic acid product yield 97.4%, in conjunction with the result of embodiment 2, by iminodiacetonitrile through lime hydrolysis, sulfuric acid acidification, the total yield of iminodiacetic acid prepared is: 90.7% %, the total yield of calcium sulfate hemihydrate is greater than 99%.

Example 11 Preparation of Ammonium Sulfate and Calcium Carbonate from Crude Gypsum

Mix the crude gypsum obtained in Example 8 (30 g, containing 23.5 g of calcium sulfate hemihydrate) with water (30 g), raise the temperature to 45-55°C, and inject ammonia and carbon dioxide into the solution while stirring. After reacting for 1.5-2 h, the resulting solution was filtered and concentrated to obtain ammonium sulfate crystals (18.2 g), with a yield of 85.1%; after the filter cake was dried, calcium carbonate powder (15.3 g, containing 13.8 g of calcium carbonate, average particle size diameter of 7.8 μm); the solution can also be directly concentrated and dried without separation to obtain ammonium sulfate-calcium carbonate complex (36 g, containing 18.2 g of ammonium sulfate and 13.8 g of calcium carbonate).

Example 12 Preparation of calcium iminodiacetate by hydrolyzing iminodiacetonitrile with lime + sodium sulfate

Put lime (31.4g, 98%, 0.55 mol) and anhydrous sodium sulfate (85.2g, 99%, 0.65 mol) into water (200g), and stir for 15 min. Keeping the temperature at about 50°C, add iminodiacetonitrile (50g, 95%, 0.5mol) in portions, and complete the addition in about half an hour. Stir at 50-55°C for 0.5-1 h, heat up to about 90-100°C, deamination under reduced pressure for 1-2 hours, stop deamination when the pH of the water vapor is 8-9. The solution was filtered and washed.

The crude product of calcium iminodiacetic acid (100.9g, containing iminodiacetic acid: 48.1g, no other impurities were seen on ¹ H NMR) was obtained in the experiment, the filtrate was combined with washing liquid (containing iminodiacetic acid: 16.4g), iminodiacetic acid The total yield is 96.9%.

Example 13 Lime + a small amount of sodium sulfate to hydrolyze iminodiacetonitrile to prepare calcium iminodiacetate

Put lime (31.4g, 98%, 0.55 mol) and anhydrous sodium sulfate (7.2g, 99%, 0.055 mol) into water (200g), and stir for 15 min. Keeping the temperature at about 50°C, add iminodiacetonitrile (50g, 95%, 0.5mol) in portions, and complete the addition in about half an hour. Stir at 50-55°C for 0.5-1 h, heat up to about 90-100°C, deamination under reduced pressure for 1-2 hours, stop deamination when the pH of the water vapor is 8-9. The solution was filtered and washed.

The experiment obtained the crude product of calcium iminodiacetic acid (86.9g, containing 47.8g of iminodiacetic acid, no other impurities were found on ¹ H NMR), the filtrate was combined with washing liquid (containing 15.8g of iminodiacetic acid), the total amount of iminodiacetic acid The yield was 95.7%.

Example 14 Preparation of calcium iminodiacetate by hydrolyzing iminodiacetonitrile reaction mixture with milk of lime

Add 13.6 g of lime to 50 g of the reaction mixture of iminodiacetonitrile (9.9 g of iminodiacetonitrile, 0.7 g of aminoacetonitrile, 0.5 g of ammoniatriacetonitrile, 0.8 g of hydroxyacetonitrile, and 6.2 g of ammonium sulfate), Keep the temperature at about 50-55°C and stir for 2 hours, raise the temperature to about 90-100°C, remove ammonia under reduced pressure, and replenish water in time. When the normal water vapor pH is 8-9, stop the deamination. The solution was filtered and the solids were washed.

The crude product of calcium iminodiacetic acid (24.3g, containing 11.7-g of iminodiacetic acid, no other impurities were seen on ¹ H NMR) was obtained in the experiment, and the filtrate was combined with washing liquid (119.7-g, containing 1.6-g of iminodiacetic acid), The total yield of iminodiacetic acid was 95.8%.

Example 15 Lime + Sodium Sulfate Alkaline Hydrolysis to Prepare Glycine

Hydroxyacetonitrile (50.0 g, 40.1%, 0.35 mol) was added to aqueous ammonia (83.5 g, 25.0%, 1.23 mol) at 40°C. Stir and react at 50°C for 1h, add the ammoniated solution dropwise into a mixed aqueous solution of lime (9.8g, 98%, 0.175mol) and sodium sulfate (12.5g, 99.0%, 0.09mol), perform alkaline hydrolysis at 70°C for 2h, and heat up to Deamination under reduced pressure at around 100°C, stop deamination when the pH of the evaporated water vapor is 8-9. Filter, wash, and combine the filtrate and washing water.

Filtrate combined washing liquid (111.8g, containing iminodiacetic acid 4.4g, glycine 19.4g, nitrilotriacetic acid 0.5g, glycolic acid 0.9g), filter residue (13.3g, containing iminodiacetic acid 0.2g, glycine 0.1g, NMR of nitrilotriacetic acid and glycolic acid was not detected).

Claims (9)

1. A clean production method for amino acids such as iminodiacetic acid, the method comprising the following steps: (1) Add product, raw material or mother liquor containing iminodiacetonitrile and/or aminoacetonitrile in milk of lime, react after 0.5-3 hour, deamination and control deamination end point is 8-9 at the pH of ammonia-containing water vapor, through Filtration, washing, separation of iminodiacetic acid calcium crude product filter cake, alkaline hydrolysis mother liquor and washing water as quicklime water recycling or direct acidification acidification crystallization; (2) Add the crude iminodiacetic acid calcium filter cake obtained in step (1) into water or the crystallization mother liquor of iminodiacetic acid to stir and disperse, add sulfuric acid to acidify, filter out the inorganic calcium salt filter cake with little water solubility, wash and filter cake, the washing liquid is combined for the next batch of diluted concentrated sulfuric acid material, and the filtrate is a solution containing iminodiacetic acid; (3) Cool the filtrate obtained in step (2), crystallize under stirring, filter and wash, the resulting filter cake is iminodiacetic acid crystals, and the crystallization mother liquor is recycled and used in step (2). 2. method according to claim 1, wherein, the gypsum byproduct that iminodiacetate crude product is acidified with sulfuric acid obtains is suspended in the ammoniacal liquor of by-product and feeds the ammoniacal liquor that carbon dioxide and alkali hydrolysis workshop section produces, and after reaction finishes , filtered, washed, and the resulting solid is calcium carbonate; the filtrate is cooled or concentrated and crystallized to separate ammonium sulfate, and the mother liquor continues to be used mechanically; the generated gypsum or the further converted calcium carbonate-ammonium sulfate reaction mixture can also be directly used as a compound fertilizer raw material without separation. . 3. The method according to claim 1, wherein, in step (1), the mass ratio of iminodiacetonitrile or aminoacetonitrile and calcium oxide is 1:0.1-1.0, and the reaction temperature is 50-90° C.; The deamination temperature is controlled at 70-105°C. 4. The method according to any one of claims 1-3, wherein, in step (1), lime is digested with clear water, or digested with an aqueous solution containing sodium sulfate, potassium sulfate or the last batch of alkaline hydrolysis mother liquor. 5. according to the method described in any one of claim 1-3, wherein, in step (2), the mol ratio of the total acid amount of sulfuric acid and the iminodiacetic acid in the calcium iminodiacetic acid crude product is 1-3: 1. The pH of the acidification end point is 2, the acidification temperature is 50-105°C, and the acidification time is 0.5h-5h. 6. The method according to any one of claims 1-3, wherein, in step (2), the amount of sulfuric acid added in the gypsum washing water is preferably 30%-50% of the amount required for the following batch of acidification reactions, washing The temperature is controlled above 60°C. 7. The method according to claim 2, wherein the reaction temperature is 30-70°C, and the reaction time is 0.5-5h. 8. The method according to claim 1, the material after alkaline hydrolysis deamination can be directly acidified without separation, and after the insoluble inorganic calcium salt is separated, the amino acid product is crystallized, and the mother liquor is used mechanically. 9. The method according to claim 1, the end point of the acid-adjusting acidification of the filtrate after isolating the calcium iminodiacetate solid is the isoelectric point of the corresponding amino acid.