CN111186848A - Process and device for refining byproduct ammonium sulfate in isophthalonitrile production - Google Patents
Process and device for refining byproduct ammonium sulfate in isophthalonitrile production Download PDFInfo
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- CN111186848A CN111186848A CN202010142965.XA CN202010142965A CN111186848A CN 111186848 A CN111186848 A CN 111186848A CN 202010142965 A CN202010142965 A CN 202010142965A CN 111186848 A CN111186848 A CN 111186848A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/24—Sulfates of ammonium
- C01C1/242—Preparation from ammonia and sulfuric acid or sulfur trioxide
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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Abstract
The invention belongs to the technical field of fine chemical engineering and pesticides, and particularly relates to a refining process and a refining device for a byproduct ammonium sulfate in isophthalonitrile production. Hydrogen peroxide is adopted to oxidize and decompose complex cyanogen and COD, diatomite is added for adsorption and filtration after oxidation is completed, flocs in the ammonium sulfate solution are removed through filter pressing, and refined ammonium sulfate is obtained after reduced pressure evaporation, cooling and centrifugation; the device, including the crude ammonium sulfate dissolving kettle, the refined cauldron of ammonium sulfate, plate and frame filter and the ammonium sulfate evaporation crystallization cauldron that connect gradually, ammonium sulfate evaporation crystallization cauldron top and vacuum system are connected, ammonium sulfate evaporation crystallization cauldron bottom is connected with high-speed centrifuge. The invention adopts the process of combining chemical oxidation and physical adsorption, the content of total cyanide of the treated ammonium sulfate salt can be reduced to be below 0.05ppm, the color whiteness is greatly improved, the product quality is far higher than the ammonium sulfate salt sold in the current market, and simultaneously, the concentration of the cyanogen complex is greatly reduced, and the environmental pressure can be reduced.
Description
Technical Field
The invention belongs to the technical field of fine chemical engineering and pesticides, and particularly relates to a refining process and a refining device for a byproduct ammonium sulfate in isophthalonitrile production.
Background
The molecular formula of the isophthalonitrile is C8H4N2The material is white needle crystal. Slightly soluble in hot water, soluble in hot ethanol, diethyl ether, benzene and chloroform. The product is used as raw material for preparing pesticide chlorothalonil and antiseptic, and also as curing agent for polyurethane resin and epoxy resin. The mixed gas composed of m-xylene, ammonia and air is passed through a vanadium-based catalyst, the reaction temperature is 400-425 ℃, and the contact time is about 3 s. The m-phthalonitrile with the purity of more than 91 percent is obtained, and the yield is more than 93 percent. The method is also the most main production method of the prior m-phthalonitrile, and in order to improve the conversion rate of m-xylene in the reaction process, the reaction molar ratio of the m-xylene, ammonia gas and air is 1:5.5: 35. This causes an excess of ammonia gas, and it is currently common practice to use dilute sulfuric acid to absorb the excess ammonia gas to produce ammonium sulfate. The reaction equation for the preparation of isophthalonitrile is as follows:
due to the excessive ammonia and air, a small amount of m-phthalonitrile is excessively oxidized to generate free-CN and short-chain organic matters, so that COD (chemical oxygen demand) and total cyanogen in the recovered ammonium sulfate are high, and if the ammonium sulfate is directly sold as a byproduct, the product quality is not high and the value is low; meanwhile, if the complex cyanogen is not used properly, the complex cyanogen enters the environment and generates potential danger to soil and water sources.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the defects of the prior art are overcome, the by-product ammonium sulfate refining process and the device in the production of the m-phthalonitrile are provided, the problem that COD (chemical oxygen demand) and total cyanogen are higher in the recovered ammonium sulfate can be solved, the quality of the ammonium sulfate product is improved, and the environmental pressure is reduced.
The refining process of the byproduct ammonium sulfate in the production of the isophthalonitrile comprises the following steps:
(1) dissolving the crude ammonium sulfate, adjusting the pH value of the crude ammonium sulfate solution to 3-5, then adding hydrogen peroxide for oxidation reaction, and obtaining reaction liquid after the reaction is finished;
(2) adjusting the pH value of the reaction liquid to 6-7, adding diatomite for adsorption, and performing filter pressing after adsorption to obtain a filtrate;
(3) evaporating the filtrate under reduced pressure, cooling, and centrifuging to obtain fine ammonium sulfate.
In the step (1), the crude ammonium sulfate is dissolved by adding water until the mass fraction of the crude ammonium sulfate solution is 20-40%.
The mass fraction of the hydrogen peroxide in the step (1) is 20-40%, and the mass ratio of the hydrogen peroxide to the crude ammonium sulfate is 0.5-1.5: 100.
The temperature of the oxidation reaction in the step (1) is 30-50 ℃, and the reaction time is 3-5 h.
The mass ratio of the crude ammonium sulfate to the diatomite is 100:1-1000: 1.
The vacuum degree of the reduced pressure evaporation in the step (3) is-0.08 to-0.09 MPa, and the temperature is 70-80 ℃.
Further, the refining process of the byproduct ammonium sulfate in the production of the isophthalonitrile comprises the following steps:
(1) dissolving the crude ammonium sulfate in water until the mass fraction of the crude ammonium sulfate solution is 20-40%, stirring and fully dissolving, dropwise adding dilute sulfuric acid to adjust the pH of the crude ammonium sulfate solution to 3-5, then adding hydrogen peroxide, heating to 30-50 ℃, preserving heat and oxidizing for 3-5h, and obtaining a reaction solution after the oxidation reaction is finished;
(2) adding ammonia water into the reaction solution to adjust the pH value to 6-7, then adding diatomite, keeping the temperature, stirring for 0.5-1h for adsorption, performing plate-and-frame filter pressing after adsorption is finished, and separating flocculates to obtain a filtrate;
(3) heating the filtrate to 70-80 ℃, adjusting the vacuum degree to-0.08-0.09 MPa, performing reduced pressure evaporation, introducing cooling circulating water after evaporation, stirring and cooling to normal temperature, and centrifuging the ammonium sulfate solution containing crystals to obtain fine ammonium sulfate.
The invention adopts hydrogen peroxide to oxidize and decompose complex cyanogen and COD under proper conditions, adds filter aid and adsorbent to carry out adsorption filtration after oxidation is finished, and carries out filter pressing by utilizing a plate-and-frame filter to remove flocculates in the ammonium sulfate solution so as to obtain clear ammonium sulfate solution. Conveying the ammonium sulfate solution to an evaporation kettle by a pump for reduced pressure evaporation to prepare the supersaturated ammonium sulfate solution. And then cooling and crystallizing, and centrifuging by a high-speed centrifuge to obtain a fine ammonium sulfate product.
The device comprises a crude ammonium sulfate dissolving kettle, an ammonium sulfate refining kettle, a plate frame filter and an ammonium sulfate evaporation crystallization kettle which are sequentially connected, wherein a crude ammonium sulfate ammonia feeding port and a water inlet are formed in the crude ammonium sulfate dissolving kettle, a diatomite feeding port is formed in the ammonium sulfate refining kettle, the top of the ammonium sulfate refining kettle is respectively connected with a hydrogen peroxide storage tank, an ammonia water storage tank and a dilute sulfuric acid storage tank, the top of the ammonium sulfate evaporation crystallization kettle is connected with a vacuum system, and the bottom of the ammonium sulfate evaporation crystallization kettle is connected with a high-speed centrifuge.
Preferably, a crude ammonium sulfate delivery pump is arranged between the crude ammonium sulfate dissolving kettle and the ammonium sulfate refining kettle; an ammonium sulfate delivery pump is arranged between the ammonium sulfate refining kettle and the plate frame filter.
Preferably, the top of the ammonium sulfate evaporative crystallization kettle is sequentially connected with a first-stage condenser and a second-stage condenser, and the second-stage condenser is connected with a vacuum system. The first-stage condenser and the second-stage condenser are both connected with the condensed water collecting tank.
During operation, adding crude ammonium sulfate and water into a crude ammonium sulfate dissolving kettle, dissolving the crude ammonium sulfate into a 20-40% aqueous solution, stirring for full dissolution, pumping the dissolved crude ammonium sulfate solution into an ammonium sulfate refining kettle through a crude ammonium sulfate delivery pump, dropwise adding dilute sulfuric acid to adjust the pH to 3-5, adding hydrogen peroxide, heating to 30-50 ℃ for thermal insulation oxidation for 3-5h, adding ammonia water to adjust the pH to 6-7 after oxidation, adding diatomite from a diatomite feeding port, stirring for 0.5-1h under thermal insulation, delivering the ammonium sulfate solution completely oxidized and decomposed to a plate frame filter by an ammonium sulfate delivery pump for plate frame filter pressing, separating flocculate, pumping the filtered ammonium sulfate solution into an ammonium sulfate evaporation crystallization kettle, heating to 70-80 ℃, adjusting the vacuum degree to-0.08-0.09 MPa by a vacuum system, and (3) carrying out reduced pressure evaporation, condensing the gas from the top of the ammonium sulfate evaporation crystallization kettle through a primary condenser and a secondary condenser, then recovering the gas to a condensate water collecting tank, introducing cooling circulating water into a jacket of the ammonium sulfate evaporation crystallization kettle after evaporation is finished, stirring and cooling the gas to normal temperature, and centrifuging an ammonium sulfate solution containing crystals by a high-speed centrifuge to obtain fine ammonium sulfate.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts the process of combining chemical oxidation and physical adsorption to treat the chromogenic organic complex and cyanide in the ammonium sulfate, the content of the total cyanide of the treated ammonium sulfate can be reduced to below 0.05ppm, the color whiteness is greatly improved, and the product quality is far higher than that of the ammonium sulfate sold in the current market. Meanwhile, the concentration of medium complex cyanogen and COD of the refined ammonium sulfate salt is greatly reduced, and the environmental pressure can be reduced.
2. The device adopted by the invention has the advantages of scientific and reasonable structure, simplicity, easy operation and high working efficiency, and can effectively recover the evaporated gas and avoid the pollution to the environment.
Drawings
FIG. 1 is a schematic structural view of the present invention;
in the figure: 1. a crude product ammonium sulfate dissolving kettle; 101. a crude ammonium sulfate ammonia feeding port; 102. a water inlet; 2. a crude ammonium sulfate delivery pump; 3. a hydrogen peroxide storage tank; 4. an ammonia water storage tank; 5. a dilute sulfuric acid storage tank; 6. an ammonium sulfate refining kettle; 601. a diatomite feeding port; 7. an ammonium sulfate delivery pump; 8. a plate frame filter; 9. evaporating and crystallizing the ammonium sulfate in a kettle; 10. a first-stage condenser; 11. a secondary condenser; 12. a vacuum system; 13. a condensed water collection tank; 14. a high-speed centrifuge.
Detailed Description
The invention is further described below with reference to the figures and examples.
As shown in fig. 1, m-phthalonitrile production in byproduct ammonium sulfate refining plant, including the crude ammonium sulfate solution cauldron 1 that connects gradually, the refined cauldron 6 of ammonium sulfate, plate and frame filter 8 and ammonium sulfate evaporation crystallization cauldron 9, be equipped with crude ammonium sulfate ammonia dog-house 101 and water entry 102 on the crude ammonium sulfate solution cauldron 1, be equipped with diatomaceous earth dog-house 601 on the refined cauldron 6 of ammonium sulfate, 6 tops of the refined cauldron of ammonium sulfate are connected with hydrogen peroxide solution storage tank 3, aqueous ammonia storage tank 4 and dilute sulphuric acid storage tank 5 respectively, ammonium sulfate evaporation crystallization cauldron 9 tops be connected with one-level condenser 10 and secondary condenser 11 in proper order, secondary condenser 11 is connected with vacuum system 12, one-level condenser 10 and secondary condenser 11 all be connected with condensate collection tank 13, ammonium sulfate evaporation crystallization cauldron 9 bottoms are connected with high speed centrifuge 14.
A crude ammonium sulfate delivery pump 2 is arranged between the crude ammonium sulfate dissolving kettle 1 and the ammonium sulfate refining kettle 6; an ammonium sulfate delivery pump 7 is arranged between the ammonium sulfate refining kettle 6 and the plate frame filter 8.
In the following examples, crude ammonium sulfate with a content of 97% was used.
Example 1
1000kg of crude ammonium sulfate is added into a crude ammonium sulfate dissolving kettle 1, water is added to dissolve the crude ammonium sulfate into a 30% aqueous solution, and the mixture is stirred and fully dissolved. And pumping the dissolved crude ammonium sulfate solution into an ammonium sulfate refining kettle 6 through a crude ammonium sulfate delivery pump 2, dropwise adding dilute sulfuric acid to adjust the pH value to 4, and adding 6kg of 30% hydrogen peroxide. Heating to 35 ℃ for heat preservation and oxidation for 4h, and adding ammonia water to adjust the pH value to 6.5 after oxidation. 2kg of diatomite is added from a diatomite feeding port 601, and the mixture is stirred for 0.5h under heat preservation. The ammonium sulfate solution which is completely oxidized and decomposed is conveyed to a plate frame filter 8 by an ammonium sulfate conveying pump 7 to be subjected to plate frame filter pressing, and flocculate is separated. The filtered ammonium sulfate solution is injected into an ammonium sulfate evaporation crystallization kettle 9, heated to 70 ℃, and vacuum degree is adjusted to-0.08 MPa by a vacuum system 12 for reduced pressure evaporation. After the evaporation, cooling circulating water is introduced into a jacket of the ammonium sulfate evaporative crystallization kettle 9 to be stirred and cooled to normal temperature. The ammonium sulfate solution containing the crystals is centrifuged by a high speed centrifuge 14 to obtain a fine ammonium sulfate.
Example 2
1500kg of crude ammonium sulfate is added into a crude ammonium sulfate dissolving kettle 1, water is added to dissolve the crude ammonium sulfate into 40 percent of water solution, and the mixture is stirred and fully dissolved. And pumping the dissolved crude ammonium sulfate solution into an ammonium sulfate refining kettle 6 through a crude ammonium sulfate delivery pump 2, dropwise adding dilute sulfuric acid to adjust the pH value to 5, and adding 15kg of 30% hydrogen peroxide. Heating to 40 ℃ for heat preservation and oxidation for 4h, and adding ammonia water to adjust the pH to 7 after oxidation. 3kg of diatomaceous earth was added from a diatomaceous earth inlet 601, and stirred for 1 hour under heat preservation. The ammonium sulfate solution which is completely oxidized and decomposed is conveyed to a plate frame filter 8 by an ammonium sulfate conveying pump 7 to be subjected to plate frame filter pressing, and flocculate is separated. Pumping the filtered ammonium sulfate solution into an ammonium sulfate evaporation crystallization kettle 9, heating to 75 ℃, adjusting the vacuum degree to-0.085 MPa by a vacuum system 12, and carrying out reduced pressure evaporation. After the evaporation, cooling circulating water is introduced into a jacket of the ammonium sulfate evaporative crystallization kettle 9 to be stirred and cooled to normal temperature. The ammonium sulfate solution containing the crystals is centrifuged by a high speed centrifuge 14 to obtain a fine ammonium sulfate.
Example 3
1500kg of crude ammonium sulfate is added into a crude ammonium sulfate dissolving kettle 1, water is added to dissolve the crude ammonium sulfate into a 30% aqueous solution, and the mixture is stirred and fully dissolved. And pumping the dissolved crude ammonium sulfate solution into an ammonium sulfate refining kettle 6 through a crude ammonium sulfate delivery pump 2, dropwise adding dilute sulfuric acid to adjust the pH value to 3, and adding 20kg of 30% hydrogen peroxide. Heating to 50 ℃ for heat preservation and oxidation for 5h, and adding ammonia water to adjust the pH value to 6 after oxidation. 2.5kg of diatomaceous earth was added from a diatomaceous earth inlet 601, and stirred for 1 hour under heat preservation. The ammonium sulfate solution which is completely oxidized and decomposed is conveyed to a plate frame filter 8 by an ammonium sulfate conveying pump 7 to be subjected to plate frame filter pressing, and flocculate is separated. The filtered ammonium sulfate solution is injected into an ammonium sulfate evaporation crystallization kettle 9, heated to 80 ℃, and vacuum degree is adjusted to-0.09 MPa by a vacuum system 12 for reduced pressure evaporation. After the evaporation, cooling circulating water is introduced into a jacket of the ammonium sulfate evaporative crystallization kettle 9 to be stirred and cooled to normal temperature. The ammonium sulfate solution containing the crystals is centrifuged by a high speed centrifuge 14 to obtain a fine ammonium sulfate.
The chroma, COD and cyanogen complex in the crude ammonium sulfate before treatment and the refined ammonium sulfate after treatment in examples 1-3 were analyzed by standard detection methods commonly used in the prior art, and the analytical data are shown in Table 1.
TABLE 1 examples 1-3 Performance data of crude ammonium sulfate before and after treatment
Of course, the foregoing is only a preferred embodiment of the invention and should not be taken as limiting the scope of the embodiments of the invention. The present invention is not limited to the above examples, and equivalent changes and modifications made by those skilled in the art within the spirit and scope of the present invention should be construed as being included in the scope of the present invention.
Claims (10)
1. A refining process of by-product ammonium sulfate in the production of isophthalonitrile is characterized in that: the method comprises the following steps:
(1) dissolving the crude ammonium sulfate, adjusting the pH value of the crude ammonium sulfate solution to 3-5, then adding hydrogen peroxide for oxidation reaction, and obtaining reaction liquid after the reaction is finished;
(2) adjusting the pH value of the reaction liquid to 6-7, adding diatomite for adsorption, and performing filter pressing after adsorption to obtain a filtrate;
(3) evaporating the filtrate under reduced pressure, cooling, and centrifuging to obtain fine ammonium sulfate.
2. The refining process of ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, comprising: in the step (1), the crude ammonium sulfate is dissolved by adding water until the mass fraction of the crude ammonium sulfate solution is 20-40%.
3. The refining process of ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, comprising: the mass fraction of the hydrogen peroxide in the step (1) is 20-40%, and the mass ratio of the hydrogen peroxide to the crude ammonium sulfate is 0.5-1.5: 100.
4. The refining process of ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, comprising: the temperature of the oxidation reaction in the step (1) is 30-50 ℃, and the reaction time is 3-5 h.
5. The refining process of ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, comprising: the mass ratio of the crude ammonium sulfate to the diatomite is 100:1-1000: 1.
6. The refining process of ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, comprising: the vacuum degree of the reduced pressure evaporation in the step (3) is-0.08 to-0.09 MPa, and the temperature is 70-80 ℃.
7. The apparatus for refining ammonium sulfate as a by-product in the production of isophthalonitrile according to claim 1, wherein: including the crude ammonium sulfate dissolving kettle (1), the refined cauldron of ammonium sulfate (6), plate and frame filter (8) and the ammonium sulfate evaporation crystallization cauldron (9) that connect gradually, be equipped with crude ammonium sulfate ammonia dog-house (101) and water entry (102) on crude ammonium sulfate dissolving kettle (1), be equipped with diatomaceous earth dog-house (601) on the refined cauldron of ammonium sulfate (6), the refined cauldron of ammonium sulfate (6) top is connected with hydrogen peroxide solution storage tank (3), aqueous ammonia storage tank (4) and dilute sulfuric acid storage tank (5) respectively, ammonium sulfate evaporation crystallization cauldron (9) top is connected with vacuum system (12), and ammonium sulfate evaporation crystallization cauldron (9) bottom is connected with high-speed centrifuge (14).
8. The apparatus for refining ammonium sulfate as a byproduct in the production of isophthalonitrile according to claim 7, wherein: a crude ammonium sulfate delivery pump (2) is arranged between the crude ammonium sulfate dissolving kettle (1) and the ammonium sulfate refining kettle (6); an ammonium sulfate delivery pump (7) is arranged between the ammonium sulfate refining kettle (6) and the plate frame filter (8).
9. The apparatus for refining ammonium sulfate as a byproduct in the production of isophthalonitrile according to claim 7, wherein: the top of the ammonium sulfate evaporation crystallization kettle (9) is sequentially connected with a first-stage condenser (10) and a second-stage condenser (11), and the second-stage condenser (11) is connected with a vacuum system (12).
10. The apparatus for refining ammonium sulfate as a byproduct in the production of isophthalonitrile according to claim 9, wherein: the primary condenser (10) and the secondary condenser (11) are both connected with a condensed water collecting tank (13).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010142965.XA CN111186848A (en) | 2020-03-04 | 2020-03-04 | Process and device for refining byproduct ammonium sulfate in isophthalonitrile production |
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| CN202010142965.XA CN111186848A (en) | 2020-03-04 | 2020-03-04 | Process and device for refining byproduct ammonium sulfate in isophthalonitrile production |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113698020A (en) * | 2021-08-30 | 2021-11-26 | 衢州华友钴新材料有限公司 | Method for reducing chlorine and COD (chemical oxygen demand) of ammonium sulfate concentrated mother liquor |
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2020
- 2020-03-04 CN CN202010142965.XA patent/CN111186848A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113698020A (en) * | 2021-08-30 | 2021-11-26 | 衢州华友钴新材料有限公司 | Method for reducing chlorine and COD (chemical oxygen demand) of ammonium sulfate concentrated mother liquor |
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Application publication date: 20200522 |