Cyanuric acid and preparation method thereof

Abstract

The invention relates to cyanuric acid and a preparation method thereof, and belongs to the technical field of fine chemical engineering, according to the technical scheme, cyanuric acid powder is heated to 190-230 DEG C, then the cyanuric acid powder and urea particles are mixed for ultrasonic-assisted granulation, the cyanuric acid powder and the urea particles are more uniformly mixed under the action of ultrasonic waves, and the cyanuric acid powder and the urea particles are uniformly mixed. The cyanuric acid powder is uniformly coated on the surfaces of the urea particles, and the obtained cyanuric acid coated urea particles are more uniform in particle size, so that the heat transfer efficiency is improved, the side reaction is reduced, the purity of the cyanuric acid crude product is improved, the cyanuric acid powder is coated on the surfaces of the urea particles, and the wall sticking phenomenon of the urea particles is avoided. According to the method, the ammonia gas generated by urea pyrolysis reacts with carbon dioxide to prepare cyanuric acid, so that the ammonia gas generated by urea pyrolysis is effectively recycled, carbon, nitrogen and oxygen elements in urea are fully utilized, and meanwhile, the yield of cyanuric acid is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to cyanuric acid and a preparation method thereof. Background Art

[0002] Cyanuric acid, also known as cyanuric acid, belongs to the triazine class of heterocyclic compounds and is a widely used synthetic intermediate. At present, the main method for synthesizing cyanuric acid is the urea pyrolysis method, which is mainly divided into direct pyrolysis method, molten salt pyrolysis method and solvent pyrolysis method according to the reaction medium. The direct pyrolysis method has become the mainstream process of industrial production due to its high yield and simple equipment, but it has disadvantages such as high energy consumption and wall sticking during the reaction, and the yield of cyanuric acid needs to be further improved. Therefore, it is necessary to provide a preparation method that can solve the above problems, improve the yield of cyanuric acid and avoid the occurrence of wall sticking. Summary of the invention

[0003] The object of the present invention is to provide a cyanuric acid and a preparation method thereof, wherein cyanuric acid powder and urea particles are mixed more evenly by ultrasonic assisted granulation, so that the cyanuric acid powder is evenly coated on the surface of the urea particles, and the particle size of the obtained cyanuric acid coated urea particles is more uniform, thereby improving the heat transfer efficiency, reducing the occurrence of side reactions, and thus improving the purity of the crude cyanuric acid product. The present invention coats the cyanuric acid powder on the surface of the urea particles to avoid the phenomenon of urea particles sticking to the wall. In addition, the ammonia generated by the pyrolysis of urea is effectively recycled, so that the carbon, nitrogen and oxygen elements in the urea are fully utilized, and the yield of cyanuric acid is increased.

[0004] The technical problem to be solved by the present invention is that the direct pyrolysis method has become the mainstream process of current industrial production due to its high yield and simple equipment, but it has disadvantages such as high energy consumption and wall sticking during the reaction, and the yield of cyanuric acid needs to be further improved.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for preparing cyanuric acid comprises the following steps:

[0007] A1. Heating cyanuric acid powder to 190-230° C. and then mixing with urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules;

[0008] In the ultrasonic assisted granulation process, the cyanuric acid powder is first heated to 190-230°C, and then the cyanuric acid powder and urea particles are mixed for ultrasonic assisted granulation. The temperature of the cyanuric acid powder is used to melt the surface of the urea particles, and then the cyanuric acid powder is coated on the surface of the urea particles, thereby avoiding the phenomenon of urea particles sticking to the wall. Under the action of ultrasound, the cyanuric acid powder and the urea particles are mixed more evenly, so that the cyanuric acid powder is evenly coated on the surface of the urea particles, and the particle size of the obtained cyanuric acid-coated urea particles is more uniform, thereby improving the heat transfer efficiency, reducing the occurrence of side reactions, and thus improving the purity of the crude cyanuric acid product.

[0009] Furthermore, in step A1, the mass ratio of cyanuric acid powder to urea granules is (2.3-3):1.

[0010] Furthermore, in step A1, the particle size of the cyanuric acid powder is 90-110 mesh.

[0011] Furthermore, in step A1, during the ultrasound-assisted granulation process, the ultrasonic frequency is 20-30 kHz, and the ultrasound-assisted granulation time is 1-3 min.

[0012] A2, pyrolyzing the cyanuric acid-coated urea particles at 240-270° C. to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and acid-washing the remaining portion to obtain cyanuric acid A;

[0013] Furthermore, in step A2, the pyrolysis reaction time is 5-15 minutes.

[0014] A3, extracting the ammonia generated in step A2 through a negative pressure blower, then mixing the ammonia and carbon dioxide, adding a catalyst, and reacting at 220-250° C. and 5-20 MPa for 10-15 min to obtain crude cyanuric acid 2;

[0015] In the above preparation process, ammonia generated by urea pyrolysis is reacted with carbon dioxide to prepare cyanuric acid. On the one hand, the heat carried by the ammonia generated by urea pyrolysis is effectively utilized, reducing the energy consumption generated by the reaction of ammonia and carbon dioxide. On the other hand, the ammonia generated by urea pyrolysis is effectively recycled, so that the carbon, nitrogen and oxygen elements in urea are fully utilized, while the yield of cyanuric acid is increased.

[0016] Furthermore, in step A3, the volume ratio of ammonia to carbon dioxide is (3-3.8):1.

[0017] Furthermore, in step A3, the catalyst is a mixture of ammonium chloride and ammonium sulfate; the mass ratio of ammonium chloride to ammonium sulfate is (0.5-1.5):(0.5-1.5).

[0018] Furthermore, in step A3, the amount of catalyst added is 0.8-1.5% of the total mass of ammonia and carbon dioxide.

[0019] A4. Crush the crude cyanuric acid 2, and then wash it with acid to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0020] The present invention also provides cyanuric acid prepared by the preparation method.

[0021] Beneficial effects of the present invention:

[0022] (1) In the technical solution of the present invention, cyanuric acid powder is heated to 190-230° C., and then the cyanuric acid powder and urea granules are mixed for ultrasonic-assisted granulation. The temperature of the cyanuric acid powder is used to melt the surface of the urea granules, and then the cyanuric acid powder is coated on the surface of the urea granules, thereby avoiding the phenomenon of urea granules sticking to the wall.

[0023] (2) In the technical solution of the present invention, under the action of ultrasound, cyanuric acid powder and urea particles are mixed more evenly, so that the cyanuric acid powder is evenly coated on the surface of the urea particles, and the particle size of the obtained cyanuric acid-coated urea particles is more uniform, thereby improving the heat transfer efficiency, reducing the occurrence of side reactions, and thus improving the purity of the crude cyanuric acid.

[0024] (3) In the technical solution of the present invention, ammonia generated by pyrolysis of urea is reacted with carbon dioxide to prepare cyanuric acid. On the one hand, the heat carried by the ammonia generated by pyrolysis of urea is effectively utilized, reducing the energy consumption generated by the reaction of ammonia and carbon dioxide. On the other hand, the ammonia generated by pyrolysis of urea is effectively recycled, so that the carbon, nitrogen and oxygen elements in urea are fully utilized, while the yield of cyanuric acid is increased. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The sources of the reagents in the following examples are as follows:

[0027] Urea: purchased from Sinopharm Chemical Reagent Co., Ltd., purity ≥ 99.9%.

[0028] Carbon dioxide: purchased from Xiamen Tongan Air Separation Special Gas Plant, purity> 98%.

[0029] Ammonium chloride: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0030] Ammonium sulfate: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0031] Example 1

[0032] A method for preparing cyanuric acid comprises the following steps:

[0033] A1. 2.3 kg of cyanuric acid powder was heated to 190° C., and then mixed with 1 kg of urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; wherein during the ultrasonic-assisted granulation process, the ultrasonic frequency was 20 kHz, and the ultrasonic-assisted granulation time was 3 min.

[0034] A2, pyrolyzing the cyanuric acid-coated urea particles at 240° C. for 10 min to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, and mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and pickling the remaining portion with a 20% sulfuric acid aqueous solution at a pickling temperature of 100° C. to obtain cyanuric acid A;

[0035] A3. The ammonia generated in step A2 is extracted by a negative pressure blower, and then the ammonia and carbon dioxide are mixed (the volume ratio of ammonia and carbon dioxide is 3:1), and ammonium chloride and ammonium sulfate are added (the mass ratio of ammonium chloride and ammonium sulfate is (0.5:1.5), and the total mass of ammonium chloride and ammonium sulfate is 0.8% of the total mass of ammonia and carbon dioxide), and the mixture is reacted at 220° C. and 5 MPa for 10 min to obtain crude cyanuric acid 2;

[0036] A4. Crush the crude cyanuric acid 2, and then pickle it with a sulfuric acid aqueous solution with a mass concentration of 20% at a pickling temperature of 100° C. to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0037] Example 2

[0038] A method for preparing cyanuric acid comprises the following steps:

[0039] A1. 2.6 kg of cyanuric acid powder was heated to 200° C., and then mixed with 1 kg of urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; wherein during the ultrasonic-assisted granulation, the ultrasonic frequency was 22 kHz, and the ultrasonic-assisted granulation time was 2 min.

[0040] A2, pyrolyzing the cyanuric acid-coated urea particles at 250° C. for 10 min to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, and mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and pickling the remaining portion with a 20% sulfuric acid aqueous solution at a pickling temperature of 100° C. to obtain cyanuric acid A;

[0041] A3. The ammonia generated in step A2 is extracted by a negative pressure blower, and then the ammonia and carbon dioxide are mixed (the volume ratio of ammonia and carbon dioxide is 3.2:1), and ammonium chloride and ammonium sulfate are added (the mass ratio of ammonium chloride and ammonium sulfate is 1:1, and the total mass of ammonium chloride and ammonium sulfate is 1% of the total mass of ammonia and carbon dioxide), and the mixture is reacted at 230° C. and 10 MPa for 12 min to obtain crude cyanuric acid 2;

[0042] A4. Crush the crude cyanuric acid 2, and then pickle it with a sulfuric acid aqueous solution with a mass concentration of 20% at a pickling temperature of 100° C. to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0043] Example 3

[0044] A method for preparing cyanuric acid comprises the following steps:

[0045] A1. 2.7 kg of cyanuric acid powder was heated to 210° C., and then mixed with 1 kg of urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; wherein during the ultrasonic-assisted granulation process, the ultrasonic frequency was 25 kHz, and the ultrasonic-assisted granulation time was 2 min.

[0046] A2, pyrolyzing the cyanuric acid-coated urea particles at 260° C. for 12 min to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, and mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and pickling the remaining portion with a 20% sulfuric acid aqueous solution at a pickling temperature of 100° C. to obtain cyanuric acid A;

[0047] A3. The ammonia generated in step A2 is extracted by a negative pressure blower, and then the ammonia and carbon dioxide are mixed (the volume ratio of ammonia and carbon dioxide is 3.4:1), and ammonium chloride and ammonium sulfate are added (the mass ratio of ammonium chloride and ammonium sulfate is 0.5:1, and the total mass of ammonium chloride and ammonium sulfate is 1.1% of the total mass of ammonia and carbon dioxide). The mixture is reacted at 240° C. and 12 MPa for 13 min to obtain crude cyanuric acid 2;

[0048] A4. Crush the crude cyanuric acid 2, and then pickle it with a sulfuric acid aqueous solution with a mass concentration of 20% at a pickling temperature of 100° C. to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0049] Example 4

[0050] A method for preparing cyanuric acid comprises the following steps:

[0051] A1. 2.8 kg of cyanuric acid powder was heated to 220° C., and then mixed with 1 kg of urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; wherein during the ultrasonic-assisted granulation process, the ultrasonic frequency was 27 kHz, and the ultrasonic-assisted granulation time was 2.5 min.

[0052] A2, pyrolyzing the cyanuric acid-coated urea particles at 260° C. for 12 min to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, and mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and pickling the remaining portion with a 20% sulfuric acid aqueous solution at a pickling temperature of 100° C. to obtain cyanuric acid A;

[0053] A3. The ammonia generated in step A2 is extracted by a negative pressure blower, and then the ammonia and carbon dioxide are mixed (the volume ratio of ammonia and carbon dioxide is 3.6:1), and ammonium chloride and ammonium sulfate are added (the mass ratio of ammonium chloride and ammonium sulfate is 1:1.5, and the total mass of ammonium chloride and ammonium sulfate is 1.3% of the total mass of ammonia and carbon dioxide). The mixture is reacted at 240° C. and 13 MPa for 104 min to obtain crude cyanuric acid 2;

[0054] A4. Crush the crude cyanuric acid 2, and then pickle it with a sulfuric acid aqueous solution with a mass concentration of 20% at a pickling temperature of 100° C. to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0055] Example 5

[0056] A method for preparing cyanuric acid comprises the following steps:

[0057] A1. 3 kg of cyanuric acid powder was heated to 230° C., and then mixed with 1 kg of urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; wherein during the ultrasonic-assisted granulation process, the ultrasonic frequency was 30 kHz, and the ultrasonic-assisted granulation time was 3 min.

[0058] A2, pyrolyzing the cyanuric acid-coated urea particles at 270° C. for 15 min to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, and mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and pickling the remaining portion with a 20% sulfuric acid aqueous solution at a pickling temperature of 100° C. to obtain cyanuric acid A;

[0059] A3. The ammonia generated in step A2 is extracted by a negative pressure blower, and then the ammonia and carbon dioxide are mixed (the volume ratio of ammonia and carbon dioxide is 3.8:1), and ammonium chloride and ammonium sulfate are added (the mass ratio of ammonium chloride and ammonium sulfate is 1.5:0.5, and the total mass of ammonium chloride and ammonium sulfate is 1.5% of the total mass of ammonia and carbon dioxide). The mixture is reacted at 250° C. and 20 MPa for 15 min to obtain crude cyanuric acid 2;

[0060] A4. Crush the crude cyanuric acid 2, and then pickle it with a sulfuric acid aqueous solution with a mass concentration of 20% at a pickling temperature of 100° C. to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

[0061] Comparative Example 1

[0062] Compared with Example 3, Comparative Example 1 did not use ultrasonic assistance during the granulation process, and other steps and raw materials were synchronized with Example 3.

[0063] Comparative Example 2

[0064] Compared with Example 3, the mass of cyanuric acid powder in step A1 of comparative example 2 is 2.5 kg, and the other steps and raw materials are the same as those of example 3.

[0065] Comparative Example 3

[0066] Compared with Example 3, the mass of cyanuric acid powder in step A1 of comparative example 3 is 2 kg, and the other steps and raw materials are the same as those of example 3.

[0067] Performance Testing

[0068] According to HG / T 4818-2015 standard, the purity of the crude cyanuric acid 1 obtained in Examples 1-5 and Comparative Examples 1-3 was tested, and the yield of cyanuric acid (excluding cyanuric acid B) was calculated. The results are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] It can be seen from the data in Table 1 that the purity and yield of cyanuric acid generated by the urea pyrolysis reaction are high, and there is no wall sticking phenomenon. It can be seen from the data of Comparative Example 3 and Comparative Example 1 that due to the lack of ultrasonic treatment, the cyanuric acid powder coated on the surface of urea is not uniform enough, and the heat transfer is uneven, which leads to a decrease in the purity and yield of crude cyanuric acid. It can be seen from the data of Comparative Example 3 and Comparative Examples 2 and 3 that when the mass ratio of cyanuric acid powder to urea granules decreases, that is, the cyanuric acid powder coated on the surface of urea granules decreases, resulting in a decrease in the purity and yield of crude cyanuric acid, and a slight wall sticking phenomenon occurs.

[0073] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing cyanuric acid, characterized in that: The following steps are involved: A1. Heating cyanuric acid powder to 190-230° C. and then mixing with urea granules for ultrasonic-assisted granulation to obtain cyanuric acid-coated urea granules; A2, pyrolyzing the cyanuric acid-coated urea particles at 240-270° C. to obtain a crude cyanuric acid product 1 and ammonia gas, crushing the crude cyanuric acid product 1, mixing a portion of the obtained cyanuric acid powder with urea particles for ultrasonic-assisted granulation, and acid-washing the remaining portion to obtain cyanuric acid A; A3, extracting the ammonia generated in step A2 through a negative pressure blower, then mixing the ammonia and carbon dioxide, adding a catalyst, and reacting at 220-250° C. and 5-20 MPa for 10-15 min to obtain crude cyanuric acid 2; A4. Crush the crude cyanuric acid 2, and then wash it with acid to obtain cyanuric acid B. Mix cyanuric acid A and cyanuric acid B to obtain.

2. A method for preparing cyanuric acid according to claim 1, characterized in that: In the step A1, the mass ratio of cyanuric acid powder to urea granules is (2.3-3):

1.

3. A method for preparing cyanuric acid according to claim 1, characterized in that: In the step A1, the particle size of the cyanuric acid powder is 90-110 mesh.

4. The method for preparing cyanuric acid according to claim 1, characterized in that: In the step A1, during the ultrasound-assisted granulation process, the ultrasonic frequency is 20-30 kHz, and the ultrasound-assisted granulation time is 1-3 min.

5. The method for preparing cyanuric acid according to claim 1, characterized in that: In step A2, the pyrolysis reaction time is 5-15 minutes.

6. The method for preparing cyanuric acid according to claim 1, characterized in that: In step A3, the volume ratio of ammonia to carbon dioxide is (3-3.8):

1.

7. The method for preparing cyanuric acid according to claim 1, characterized in that: In step A3, the catalyst is a mixture of ammonium chloride and ammonium sulfate.

8. The method for preparing cyanuric acid according to claim 7, characterized in that: The mass ratio of the ammonium chloride to ammonium sulfate is (0.5-1.5):(0.5-1.5).

9. The method for preparing cyanuric acid according to claim 1, characterized in that: In step A3, the amount of catalyst added is 0.8-1.5% of the total mass of ammonia and carbon dioxide.

10. Cyanuric acid obtained by the preparation method according to any one of claims 1 to 9.

Images