WO2021114729A1

WO2021114729A1 - Synthesis method for zinc polyaspartate

Info

Publication number: WO2021114729A1
Application number: PCT/CN2020/111480
Authority: WO
Inventors: 程终发; 周响; 邱玉章; 王宁宁; 王燕平
Original assignee: 山东泰和水处理科技股份有限公司
Priority date: 2019-12-13
Filing date: 2020-08-26
Publication date: 2021-06-17
Also published as: CN110862540A; CN110862540B

Abstract

Disclosed in the present invention is a method for producing a zinc polyaspartate. Specifically, polysuccinimide (PSI) is hydrolyzed to obtain polyaspartatic acid (PASP) by controlling the pH value of the system with ammonia water, zinc hydroxide/zinc oxide is dissolved into soluble Zn(NH₃)₄(OH)₂ in the presence of an ammonium salt, which reacts with polyaspartatic acid to generate zinc polyaspartate. In the method, when PSI is hydrolyzed into PASP, zinc polyaspartate is generated from PASP, and a two-step reaction is performed simultaneously, shortening the working time and reducing energy consumption; in the method, zinc salt is reacted directly, avoiding the use of calcium polyaspartate intermediate, reducing the procedures and working time, reducing energy consumption, and avoiding the generation of a large amount of calcium salt. The method has no by-products and no waste generation, is green and environmentally friendly, and facilitates the achievement of industrial production.

Description

A kind of synthetic method of polyaspartic acid zinc salt

Technical field

The invention belongs to the technical field of industrial water treatment agent chemical industry, and specifically relates to a production method of polyaspartic acid zinc salt.

Background technique

Zinc is one of the essential trace elements of the human body. It plays an extremely important role in the growth and development of the human body. It is often called the "flower of life" and the "source of intelligence". Zinc can effectively improve the body's resistance. For the elderly, it is also meaningful to improve immunity and fight disease by supplementing zinc. In China, although the soil is rich in zinc, most of the zinc in the soil is in the form of insoluble inorganic salts such as zinc carbonate, which are not used to be absorbed by crops, resulting in widespread zinc deficiency in crops. Affected the yield and quality of crops, and also led to the current situation of zinc deficiency in Chinese citizens.

In order to solve the problem of soil zinc deficiency, high-efficiency and harmless agricultural zinc supplements have become a current research hotspot. The research direction of agricultural zinc supplements has gradually shifted from inorganic zinc to organic zinc. The focus of the research is to improve the water solubility of zinc supplements, and the organic ligands must be degradable, non-polluting, and avoid negative effects on the soil, such as those caused by sulfate. The problem of soil compaction and so on.

As a new type of organic high-efficiency zinc supplement, zinc polyaspartate has significant advantages compared with other zinc supplements: it is easily degraded in the soil and easily absorbed by plants, and it is a non-toxic and non-polluting Environmentally friendly plant zinc supplements; in addition, polyaspartate ions also have the effect of enhancing the absorption of plant nutrients and can better supplement other trace elements.

At present, some progress has been made in the preparation of zinc polyaspartate. Mainly using aspartic acid as raw material, polycondensation into polysuccinimide (PSI) of different molecular weight, and then ring-opening hydrolysis to polyaspartic acid (PASP), and then complexing zinc salt to polyaspartic acid Zinc. Aspartic acid is a common amino acid. As a conventional raw material in the food and chemical industries, it is easy to prepare and has abundant reserves, which can meet the needs of industrial production. Chinese patent CN102627766B uses calcium polyaspartate as a raw material, replaces with zinc sulfate under acidic conditions, filtered and dried to obtain high-purity zinc polyaspartate. The raw material used in this method is a downstream product of aspartic acid, which has high added value, resulting in excessive production costs, which is not conducive to product promotion. Zhang Youming et al. disclosed a method for rapidly synthesizing high-purity helical-chain zinc L-aspartate by using L-aspartic acid and zinc oxide under microwave radiation (Science in China, Chemistry, 2004, Issue 34) . This method has fast synthesis speed and high purity, but it cannot be produced on a large scale due to equipment limitations.

Summary of the invention

In view of the above-mentioned shortcomings, the present invention provides a method for producing zinc polyaspartate, which mainly includes the following steps:

A production method of polyaspartic acid zinc salt, the specific operation content includes:

(1) Add polysuccinimide, zinc source, ammonium salt and pure water to the reaction kettle, stir and heat up;

(2) Add ammonia water dropwise, maintain the pH of the system at 8-9 by controlling the acceleration and the amount of the ammonia droplets, and continue the reaction until the solid disappears completely, and an amber transparent liquid is obtained;

(3) Adjust the pH value of the system to 5-6 with dilute acid, maintain the system temperature unchanged, continue to keep the temperature for 0.5-1h, spray-dry to obtain the zinc salt of brown-yellow powder polyaspartic acid.

Wherein, the zinc source is zinc oxide or zinc hydroxide.

Wherein, the molar ratio of the polysuccinimide and zinc in the zinc source is n _PSI : n _zinc =1: 0.2n to 0.9n, where n is the average degree of polymerization of PSI.

Wherein, the amount of pure water is 1.5 to 2.0 times of the PSI feed mass; the step (1) is stirred and heated to 60-100 degrees Celsius.

Wherein, the ammonium salt is capable of forming a water-soluble zinc salt with zinc ions; the amount of the ammonium salt is 0.5-1.0% of the feed mass of the zinc source.

Wherein, the zinc source can be added in n batches, the interval of batch addition is 1 h, and n=1 to 6.

Wherein, the concentration of the ammonia water is 5-30%.

Wherein, the dilute acid is an acid that can form a water-soluble zinc salt with zinc ions, and the mass fraction of the dilute acid is 5-15%.

Wherein, in the steps (1) and (2), the tail gas recovery device is turned on all the way.

The beneficial effects of the present invention: The method uses ammonia to control the pH of the system, hydrolyze polysuccinimide (PSI) to obtain polyaspartic acid (PASP), and at the same time, dissolve zinc hydroxide/zinc oxide to be soluble in the presence of ammonium Zn(NH ₃ ) ₄ (OH) ₂ reacts with polyaspartic acid to produce zinc polyaspartate.

This method hydrolyzes PSI into PASP and at the same time generates zinc polyaspartate with PASP. The two-step reaction is carried out at the same time, which shortens the working hours and saves energy consumption; this method directly reacts with zinc salt and avoids polyaspartic acid. The use of calcium intermediates reduces the process and man-hours, saves energy and reduces consumption, and avoids the production of a large amount of calcium salts. The method has no by-products, no waste generation, is green and environmentally friendly, and is conducive to industrialization.

Detailed ways

Example 1

Add 450Kg of pure water, 300Kg of polysuccinimide (molecular weight 5000), 50Kg of zinc hydroxide and 1Kg of ammonium nitrate to the reactor in sequence, turn on the stirring and tail gas recovery device, heat up to 90±2℃, and start to slowly enter the reactor Add 10% mass fraction of ammonia water intermittently to control the pH value of the reaction solution at 8-9. Start timing from the dripping of ammonia, add 50Kg of zinc hydroxide after 1h, and add the remaining 50Kg of zinc hydroxide after 2h. After 4 hours of continuous reaction, the precipitation completely disappeared. The reaction liquid was an amber transparent liquid. Add 10% hydrochloric acid dropwise to adjust the pH of the reaction liquid to 5.8. Continue to keep the temperature for 1 hour to obtain an aqueous solution with a solid content of 41.36%. Spray-dried at ±5℃ to obtain 476.5Kg of brown-yellow powdery solid polyzinc aspartate, molecular weight of polyaspartate of 7504, solid content of 98.30%, organic zinc content of 20.59%, and ammonium chloride content of 3.32%; tail gas The absorption liquid is 101.87Kg, and the ammonia content of the exhaust gas absorption liquid is 1.84%.

Example 2

Put 156Kg of zinc hydroxide into the kettle at one time, with the other conditions unchanged, same as in Example 1, to obtain 475.8Kg of brown-yellow powdered solid polyzinc aspartate, the molecular weight of polyaspartate is 7482, and the solid content is 98.34%. The content of organic zinc is 19.11%, the content of ammonium chloride is 3.41%; the exhaust gas absorption liquid is 103.23Kg, and the ammonia content of the exhaust gas absorption liquid is 3.51% (accumulated with the previous embodiment).

Example 3

Add 600Kg of pure water, 300Kg of polysuccinimide (molecular weight 5000), 59Kg of zinc hydroxide and 1.7Kg of ammonium nitrate to the reactor in sequence, turn on the stirring and tail gas recovery device, heat up to 90±2℃, and start to add to the reactor Slowly and intermittently add 15% mass fraction of ammonia water to control the pH value of the reaction solution at 8-9. Start timing from the dripping of ammonia, add 59Kg of zinc hydroxide after 1h, and add the remaining 59Kg of zinc hydroxide after 2h. After 4 hours of continuous reaction, the precipitation completely disappeared. The reaction liquid was an amber transparent liquid. Add 20% hydrochloric acid dropwise to adjust the pH of the reaction liquid to 5.6. Continue to keep the temperature for 1 hour to obtain an aqueous solution with a solid content of 41.66%. Spray-dried at ±5℃ to obtain a brown-yellow powdery solid polyzinc aspartate 493.8Kg, polyzinc aspartate molecular weight 7511, solid content 98.77%, zinc content 23.16%, ammonium chloride content 4.46%; exhaust gas absorption Liquid 105.05Kg, the ammonia content of the exhaust gas absorption liquid is 5.28% (accumulated calculation with the above embodiment).

Comparative Example 1 (The hydrolysis pH is too low, the PSI hydrolysis is incomplete, the holding pH is too low, and the PASP is partially hydrolyzed)

Add 450Kg of pure water, 300Kg of polysuccinimide (molecular weight 5000), 50Kg of zinc hydroxide and 1Kg of ammonium nitrate to the reactor in sequence, turn on the stirring and tail gas recovery device, heat up to 90±2℃, and start to slowly enter the reactor Add 10% mass fraction of ammonia water intermittently to control the pH value of the reaction solution at 6-7. Start timing from the dripping of ammonia, add 50Kg of zinc hydroxide after 1h, and add the remaining 50Kg of zinc hydroxide after 2h. After 10 hours of continuous reaction, the precipitation did not completely disappear, and the reaction liquid was light amber turbid liquid. After filtration, the filtrate was added dropwise to the reaction kettle to adjust the pH of the reaction liquid to 3.0 by adding 10% mass fraction of hydrochloric acid, and the temperature was kept for 1 hour to obtain the solid content. A 31.57% aqueous solution, spray-dried at an inlet temperature of 170±5℃ to obtain a brownish-yellow powdery solid polyzinc aspartate 416.8Kg with a molecular weight of 6856, a solid content of 98.30%, and a zinc content of 15.59% , The content of ammonium chloride is 0.22%; the exhaust gas absorption liquid is 100.93Kg, and the ammonia content of the exhaust gas absorption liquid is 0.92%.

Comparative Example 2 (The hydrolysis pH is too high, PSI will continue to be hydrolyzed after being hydrolyzed into PASP, the molecular weight will decrease)

Add 450Kg of pure water, 300Kg of polysuccinimide (molecular weight 5000), 50Kg of zinc hydroxide and 1Kg of ammonium nitrate to the reactor in sequence, turn on the stirring and tail gas recovery device, heat up to 90±2℃, and start to slowly enter the reactor Add 25% mass fraction of ammonia water intermittently to control the pH value of the reaction solution at 11-12. Start timing from the dripping of ammonia, add 50Kg of zinc hydroxide after 1h, and add the remaining 50Kg of zinc hydroxide after 2h. After 4 hours of continuous reaction, the precipitation completely disappeared. The reaction liquid was an amber transparent liquid. Add 20% hydrochloric acid dropwise to adjust the pH of the reaction liquid to 5.8. Continue to keep the temperature for 1 hour to obtain an aqueous solution with a solid content of 33.04%. Spray-dried at ±5°C to obtain a brown-yellow powdery solid polyzinc aspartate 550.6Kg, molecular weight of polyzinc aspartate 4527, solid content 98.72%, zinc content 17.70%, ammonium chloride content 14.42%; exhaust gas absorption Liquid 110.23Kg, the ammonia content of the tail gas absorption liquid is 9.28%.

The above-mentioned embodiments only express the implementation of the patent of the present invention, and the description is more specific and detailed, but it should not be understood as a limitation to the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the patent of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the patent of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A production method of polyaspartate zinc salt, characterized in that the specific operation content includes:

(1) Add polysuccinimide, zinc source, ammonium salt and pure water to the reaction kettle, stir and heat up;

(2) Add ammonia water dropwise, maintain the pH of the system at 8-9 by controlling the acceleration of the ammonia droplets and the dropping amount, and continue the reaction until the solid disappears, and an amber transparent liquid is obtained;

(3) Adjust the pH of the system to 5-6 with dilute acid, maintain the temperature of the system unchanged, continue to keep the temperature for 0.5-1h, spray-dry to obtain the zinc salt of polyaspartic acid in brown powder.
The method for producing zinc polyaspartate according to claim 1, wherein the zinc source is zinc oxide or zinc hydroxide.
The production method of polyaspartate zinc salt according to claim 1, wherein the molar ratio of the polysuccinimide and zinc in the zinc source is n PSI : n zinc = 1: 0.2n-0.9n, where n is the average degree of polymerization of PSI.
The method for producing zinc polyaspartate according to claim 1, wherein the amount of pure water is 1.5 to 2.0 times the mass of the PSI; the step (1) is stirred and heated to 60-100 degrees Celsius .
The method for producing a zinc polyaspartate salt according to any one of claims 1 or 2, wherein the ammonium salt is capable of forming a water-soluble zinc salt with zinc ions; the amount of the ammonium salt is zinc 0.5 to 1.0% of the feed quality of the source.
The production method according to claims 1 and 2, characterized in that the zinc source can be added in n batches with an interval of 1 h, n = 1-6.
The method for producing zinc polyaspartate according to claim 1, wherein the concentration of the ammonia water is 5-30%.
The method for producing a zinc polyaspartate salt according to claim 1, wherein the dilute acid is an acid that can form a water-soluble zinc salt with zinc ions, and the mass fraction of the dilute acid is 5~ 15%.
The method for producing zinc polyaspartate according to claim 1, characterized in that, in the steps (1) and (2), the tail gas recovery device is turned on in the whole process.