CN116986984A - Adipic acid crystal re-melting, purifying and re-crystallizing method - Google Patents
Adipic acid crystal re-melting, purifying and re-crystallizing method Download PDFInfo
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- CN116986984A CN116986984A CN202310969864.3A CN202310969864A CN116986984A CN 116986984 A CN116986984 A CN 116986984A CN 202310969864 A CN202310969864 A CN 202310969864A CN 116986984 A CN116986984 A CN 116986984A
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- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 title claims abstract description 342
- 239000013078 crystal Substances 0.000 title claims abstract description 194
- 239000001361 adipic acid Substances 0.000 title claims abstract description 171
- 235000011037 adipic acid Nutrition 0.000 title claims abstract description 171
- 238000000034 method Methods 0.000 title claims abstract description 57
- 238000002844 melting Methods 0.000 title claims abstract description 32
- 238000003756 stirring Methods 0.000 claims abstract description 44
- 238000001914 filtration Methods 0.000 claims abstract description 31
- 238000000746 purification Methods 0.000 claims abstract description 31
- 239000003054 catalyst Substances 0.000 claims abstract description 25
- 238000001953 recrystallisation Methods 0.000 claims abstract description 20
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 17
- 238000005406 washing Methods 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 15
- 230000008018 melting Effects 0.000 claims abstract description 13
- 239000002904 solvent Substances 0.000 claims description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 18
- 238000002360 preparation method Methods 0.000 claims description 14
- 239000012528 membrane Substances 0.000 claims description 12
- 239000003960 organic solvent Substances 0.000 claims description 10
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 238000002425 crystallisation Methods 0.000 claims description 7
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 6
- 230000008025 crystallization Effects 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 4
- 239000012634 fragment Substances 0.000 claims description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 230000008901 benefit Effects 0.000 abstract description 12
- 239000000047 product Substances 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 238000009833 condensation Methods 0.000 abstract description 4
- 230000005494 condensation Effects 0.000 abstract description 4
- 239000007788 liquid Substances 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 4
- 239000006227 byproduct Substances 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 3
- 238000004090 dissolution Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 9
- 239000011148 porous material Substances 0.000 description 5
- 238000005119 centrifugation Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005354 coacervation Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052601 baryte Inorganic materials 0.000 description 1
- 239000010428 baryte Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000002109 crystal growth method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0036—Crystallisation on to a bed of product crystals; Seeding
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of adipic acid re-melting purification, in particular to a method for re-crystallizing adipic acid crystals by re-melting purification. Which comprises the following steps: s1, preparing seed crystals; s2, preparing a solution; s3, temperature control and stirring; s4, adding a seed crystal catalyst; s5, filtering and washing; in the adipic acid re-crystallization method, solute molecules can be effectively adsorbed by using a seed crystal catalyst, and a condensation place is provided to promote adipic acid crystals to be gradually formed, so that the purity of a product can be effectively improved, and the existence of impurities is reduced; the crystal formation rate and the crystal crystallinity can be increased by reasonably controlling the seed crystal treatment process, so that the yield and the product yield are improved; in the process of complex melting and purifying, the energy consumption and the cost of waste liquid treatment are reduced, and the raw material loss and the production of byproducts are reduced and the production benefit and the economic benefit are improved due to the repeated use of the seed crystal catalyst.
Description
Technical Field
The invention relates to the technical field of adipic acid re-melting purification, in particular to a method for re-crystallizing adipic acid crystals by re-melting purification.
Background
Adipic acid is a common chemical method for improving the purity and quality of adipic acid. However, in the prior art, there are some problems and disadvantages in the process of re-crystallization of adipic acid by re-melting purification. The following are some typical prior art:
1. extraction method: this method utilizes a solvent to extract adipic acid from an adipic acid solution, and then pure adipic acid is obtained by volatilization of the solvent. However, this method has problems of low purification efficiency, high production cost, solvent recovery, waste liquid treatment, and the like. In addition, there is a risk of fire and environmental pollution during operation.
2. Crystal growth method: adipic acid crystals are crystallized and grown in the solution by adjusting the temperature and the concentration of the adipic acid solution and the crystal growth conditions, so that the adipic acid is purified. However, this method often has problems of low purity of crystals, low yield, and non-uniformity of crystal shape and size.
3. Barite process: the method utilizes adipic acid molecules in barite structure to separate impurities, thereby improving the purity of adipic acid crystals. However, this method is low in purification efficiency and low in crystal growth rate.
4. Solvent crystallization method: the purification of adipic acid crystals is achieved by selective dissolution of specific components with a solvent. However, the solvent selection and the control of the dissolution conditions have a great influence on the purification effect, are complex to operate and are susceptible to interference from the external environment.
In summary, the prior art has some problems in the process of re-crystallization of adipic acid by re-melting purification, such as low purification efficiency, poor crystal purity, complex operation, etc. Therefore, there is a need for a method of recrystallization of adipic acid crystals by fusion purification.
Disclosure of Invention
The invention aims to provide a method for re-crystallizing adipic acid crystals by means of complex melting, purification and re-crystallization, so as to solve the problems in the prior art.
In order to achieve the above purpose, the invention provides a method for re-crystallizing adipic acid crystals by complex melting, purification and recrystallization, which comprises the following steps:
s1, preparing seed crystals: pure adipic acid crystals are prepared to be used as seed crystals;
s2, preparing a solution: mixing adipic acid crystals to be redissolved and purified with a solvent, heating and stirring until the adipic acid crystals are completely dissolved to form an adipic acid solution;
s3, temperature control and stirring: in the process of re-melting, purifying and recrystallizing adipic acid, the temperature of the solution is 70-90 ℃, and the stirring speed is 200-500rpm;
s4, crystallization is formed: adding a seed catalyst to promote the formation of adipic acid crystals in adipic acid solution;
s5, filtering and washing: separating adipic acid crystals by using a filter medium to obtain adipic acid crystals after complex melting and purification.
Preferably, in S1, the step of preparing pure adipic acid crystals as seed crystals is as follows:
s1.1, mixing adipic acid and a solvent, heating and stirring until the adipic acid and the solvent are completely dissolved;
s1.2, filtering adipic acid solution through filter paper and a filter membrane;
s1.3, slowly cooling the filtered adipic acid solution to room temperature, wherein adipic acid gradually crystallizes to form crystals in the cooling process;
s1.4, separating the crystal from the solution by a filtering and centrifuging method, and filtering by using a filter membrane to obtain wet adipic acid crystals;
s1.5, washing wet adipic acid crystals by using a cold solvent, and drying the washed adipic acid crystals at a low temperature to obtain dry adipic acid crystals.
Preferably, in S2, the preparation step of the adipic acid solution is as follows:
s2.1, preparing adipic acid crystals and a solvent, gradually adding the adipic acid crystals into the solvent, and stirring at the same time;
s2.2, continuously heating and stirring the mixture until adipic acid crystals are completely dissolved.
Preferably, the solvent is one of water and an organic solvent, and ethanol is adopted as the organic solvent.
Preferably, when the solvent is water, the water is preheated to a temperature of 70-80 ℃.
Preferably, in S4, the seed catalyst is selected from one of adipic acid crystal fragments, sodium diacid, triethylamine and pyridine.
Preferably, in S5, the steps of filtering and washing are as follows:
s5.1, filtering the solution through a filter medium to separate adipic acid crystals;
s5.2, washing adipic acid crystals by using cold water to remove impurities and solutes in the solution.
Preferably, the filter medium selects one of a filter paper, a filter funnel filtering mode and a filtering membrane filtering mode.
Compared with the prior art, the invention has the beneficial effects that:
1. in the method for re-crystallization of adipic acid crystals by re-melting purification, solute molecules can be effectively adsorbed by using a seed crystal catalyst, and a condensation place is provided to promote the gradual formation of adipic acid crystals, so that the purity of the product can be effectively improved, and the existence of impurities is reduced; the crystal formation rate and the crystal crystallinity can be increased by reasonably controlling the seed crystal treatment process, so that the yield and the product yield are improved; in the process of complex melting and purifying, the energy consumption and the cost of waste liquid treatment are reduced; in addition, the seed crystal catalyst is reused, so that the raw material loss and the production of byproducts are reduced, and the production benefit and the economic benefit are improved.
2. In the method for re-crystallization of adipic acid crystals by re-melting, purification and the like, the formation of the crystals can be more uniform and complete by reasonably regulating and controlling the temperature and the stirring speed. Thereby obtaining adipic acid crystals with better quality and improving the quality of products; compared with the traditional purification and recrystallization method, the improved method has the advantages of simpler solution preparation, temperature control, seed crystal treatment and the like, and has relatively fewer steps and easier operation.
Drawings
Fig. 1 is an overall flow diagram of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
According to the figure 1, the invention provides a method for re-crystallizing adipic acid crystals by complex melting, purification and recrystallization, which comprises the following specific steps:
1. preparation of seed crystal
The pure adipic acid crystal is prepared and used as seed crystal, and the specific steps are as follows:
1. preparing adipic acid solution: adipic acid and a solvent are mixed, heated and stirred until the adipic acid is completely dissolved, the concentration of the adipic acid solution is ensured to be higher, the crystallization yield is improved, the solvent adopts one of water and an organic solvent, and the organic solvent is ethanol.
2. And (3) filtering: the adipic acid solution is filtered through filter paper and a filter membrane to remove impurities and solid particles.
3. Cooling and crystallizing: the filtered adipic acid solution is slowly cooled to room temperature, and the temperature can be controlled by using a cold water bath or a cooler, and during the cooling process, adipic acid can gradually crystallize to form crystals.
4. Separating the crystals: the crystals are separated from the solution by filtration and centrifugation, and filtered using filter paper or a filter membrane to obtain adipic acid crystals in a wet state.
5. Washing: washing wet adipic acid crystal with cold solvent, and removing impurities and solutes in the solution with cold water.
6. And (3) drying: drying the washed adipic acid crystals at a low temperature, and removing water in the crystals until dry adipic acid crystals are obtained.
2. Solution preparation
Mixing adipic acid crystals needing to be redissolved and purified with a solvent, heating and stirring until the adipic acid crystals are completely dissolved, and specifically comprising the following steps of:
1. material preparation: preparing adipic acid crystals and a solvent, ensuring that the purity and quality of the adipic acid crystals and the solvent meet experimental requirements, wherein the solvent adopts one of water and an organic solvent, and the organic solvent is ethanol.
2. And (3) selecting a container: an appropriate container is selected to hold the mixture, ensuring that the container is clean and heat resistant.
3. Mixing adipic acid and solvent: adipic acid crystals were gradually added to the solvent in the required amount while stirring.
3.1, for water as solvent, preheating water to 70-80 ℃, then gradually adding adipic acid crystals into hot water, stirring by using a glass rod or a magnetic stirrer, and heating to accelerate the dissolution rate.
3.2, adding adipic acid crystals and the organic solvent into a container for the organic solvent as the solvent, and stirring and heating.
4. Heating and stirring: the mixture is heated to an appropriate temperature and stirring is continued until the adipic acid crystals are completely dissolved, which may be done by a hot plate or heater while stirring with a glass rod or magnetic stirrer.
5. Check the degree of dissolution: the mixture was observed for complete transparency and complete dissolution of adipic acid crystals, ensuring no visible solid particles and impurities remained.
After the above steps are completed, a completely dissolved adipic acid solution is obtained for subsequent operations.
3. Temperature control and agitation
In the scene of improved seed crystal catalyzed adipic acid redissolution purification and recrystallization, temperature control and stirring are needed to be realized, so that the temperature of the solution is adjusted to a specific range, and proper stirring is carried out. The specific operation steps are as follows:
1. determining a target temperature range: in the process of re-crystallization of adipic acid through re-melting, purification and re-crystallization, the temperature of the solution is in the range of 70-90 ℃.
2. Temperature control device: placing the container therein using a suitable temperature control device, such as a hot water bath or a thermostatic bath, etc.; the desired temperature range is set and maintained. Depending on the experimental requirements, a suitable temperature gradient may be set, for example a gradual increase in temperature or a constant temperature.
3. Stirring equipment: stirring the solution using a stirring device (e.g., a magnetic stirrer or a mechanical stirrer); ensures moderate stirring speed to achieve uniform mixing and promote the dissolution of solute; the stirring speed is 200-500rpm.
4. And (3) temperature adjustment: the solution in the container is placed in a temperature control device, gradually heated or kept at a constant temperature while stirring, and the temperature is adjusted to be within a specific range as required according to experimental requirements.
The benefits of a particular range are as follows:
(1) Improves the motion capability and solubility of the solvent and is beneficial to the rapid dissolution of the solute.
(2) Reasonable control of the solvent temperature is helpful to control the size and morphology of the crystals, thereby affecting the purity and crystallinity of the crystals.
(3) The stirring speed is adjusted within a specific temperature range, so that the full mixing of the solute and the solvent can be promoted, and the uniformity of the solution is improved.
(4) The combination of stirring and temperature control is beneficial to improving mass transfer efficiency, reducing material non-uniformity and enhancing seed crystal catalysis.
4. Crystallization formation
The addition of a pre-prepared seed catalyst may promote the formation of adipic acid crystals in solution by a seed catalytic mechanism.
The seed catalyst is a substance having a crystal structure and a specific crystal surface activity, which can provide a reference crystal, i.e., seed, in a solution; in seed catalysis, the seed catalyst adsorbs solute molecules in a solution and provides a site for condensation, so that solute molecules are gradually arranged on the surface of the seed catalyst, a nucleation reaction occurs, the seed gradually grows and deposits on the surface of the seed catalyst along with the time and aggregation of molecules, and large-particle adipic acid crystals are formed, so that the formation and growth of adipic acid crystals in the solution are realized through the action of the seed catalyst.
The seed crystal catalyst is selected from one of adipic acid crystal fragments, sodium diacid, triethylamine and pyridine, wherein the adipic acid crystal fragments are obtained by mechanically grinding adipic acid crystals which are formed; by adding the seed crystal catalyst, the formation of adipic acid crystals can be accelerated and controlled, the purity and crystallinity of the crystals are improved, and more efficient redissolution purification and recrystallization processes are realized.
5. Filtration and washing
The principle of separating adipic acid crystals using a suitable filter medium is based on particle size differences and sieving action, the filter medium having a pore size or mesh size that allows the solvent and smaller particles in solution to pass through, but larger crystal particles are blocked on the filter medium, thereby effecting separation of the crystals.
Suitable filter media are generally materials having a smaller pore size or mesh size, such as filter papers, filter membranes, filter capillaries, and the like. The advantages of using these media are:
1. and (3) accurate control: these filter media can be selected to have an appropriate pore size or mesh size depending on the crystal size requirements, thereby achieving accurate screening and separation of the crystals.
2. High-efficiency separation: the pore diameter of the filter medium is smaller, so that larger crystal particles can be effectively blocked, and the separation efficiency of crystals is improved.
3. Protection of crystal morphology: the fine pore diameter of the filter medium can reduce the contact area of the crystal to the filter medium, reduce the damage and deformation of the crystal and protect the integrity of the crystal form.
The method for re-crystallization of adipic acid crystals by re-melting purification provided by the invention is further illustrated by the following specific examples according to different process conditions.
Example 1
1. Seed crystal preparation:
materials: pure adipic acid;
solvent: water;
the device comprises: beaker, heater, stirring rod, filter paper and centrifuge;
the preparation method of the adipic acid solution comprises the following steps:
(1) Adding adipic acid to the beaker;
(2) Adding water, stirring and heating until the water is completely dissolved;
(3) Filtering the solution to remove impurities and solid particles;
(4) Slowly cooling the filtered solution to room temperature to crystallize adipic acid to form crystals;
(5) Separating the crystals from the solution by filtration and centrifugation, and obtaining adipic acid crystals in a wet state;
(6) Washing wet adipic acid crystals with cold water to remove impurities and solutes in the solution;
(7) The washed adipic acid crystals are dried at low temperature until dry adipic acid crystals are obtained.
2. Preparing a solution:
materials: adipic acid crystals to be redissolved and purified;
solvent: ethanol and water;
the device comprises: a container, a magnetic stirrer, and a heating plate;
the preparation method comprises the following steps:
(1) Preparing adipic acid crystals and ethanol, and ensuring that the purity and the quality meet the requirements;
(2) Selecting a proper container, and cleaning;
(3) Gradually adding adipic acid crystals into ethanol in a container, and stirring at the same time;
(4) Placing the container on a heating plate, heating and continuously stirring until adipic acid crystals are completely dissolved;
(5) The solution was checked for transparency to confirm complete dissolution of adipic acid crystals.
3. Temperature control and stirring:
the device comprises: hot water bath or constant temperature tank and magnetic stirrer
The steps are as follows:
(1) Determining the temperature range to be 70-90 ℃ according to the requirement;
(2) Placing the solution container into a hot water bath or a constant temperature tank, and setting and maintaining a required temperature range;
(3) A magnetic stirrer was added to the solution and the stirring speed was adjusted to 200-500rpm.
4. Crystallization is formed:
the device comprises: seed catalyst
A crystal formation step:
(1) Adding a seed catalyst prepared in advance into the adipic acid solution;
(2) The seed catalyst adsorbs solute molecules in the solution and provides a coacervation site that promotes the gradual formation of adipic acid crystals.
5. Filtration and washing:
materials: a filter paper;
the device comprises: a filter funnel;
the steps are as follows:
(1) Filtering the solution through filter paper and a filter funnel to separate adipic acid crystals;
(2) The adipic acid crystals were washed with cold water to remove impurities and solutes from the solution.
Example 2
1. Seed crystal preparation:
materials: pure adipic acid;
solvent: ethanol;
the device comprises: beaker, heater, stirring rod, filter paper and centrifuge;
the preparation method of the adipic acid solution comprises the following steps:
(1) Adding adipic acid to the beaker;
(2) Adding ethanol, stirring and heating to dissolve completely;
(3) Filtering the solution to remove impurities and solid particles;
(4) Slowly cooling the filtered solution to room temperature to crystallize adipic acid to form crystals;
(5) Separating the crystals from the solution by filtration and centrifugation, and obtaining adipic acid crystals in a wet state; (6) Washing wet adipic acid crystals with cold ethanol to remove impurities and solutes in the solution;
(7) The washed adipic acid crystals are dried at low temperature until dry adipic acid crystals are obtained.
2. Preparing a solution:
materials: adipic acid crystals to be redissolved and purified;
solvent: water;
the device comprises: a container, a magnetic stirrer, and a heating plate;
the preparation method comprises the following steps:
(1) Preparing adipic acid crystals and water, and ensuring that the purity and the quality meet the requirements;
(2) Selecting a proper container, and cleaning;
(3) Gradually adding adipic acid crystals into water in a container while stirring;
(4) Placing the container on a heating plate, heating and continuously stirring until adipic acid crystals are completely dissolved; (5) The solution was checked for transparency to confirm complete dissolution of adipic acid crystals.
3. Temperature control and stirring:
the device comprises: constant temperature bath and magnetic stirrer;
the steps are as follows:
(1) Determining the temperature range to be 70-90 ℃ according to the requirement;
(2) Placing the solution container into a constant temperature tank, and setting and maintaining a required temperature range;
(3) A magnetic stirrer was added to the solution and the stirring speed was adjusted to 200-500rpm.
4. Crystallization is formed:
the device comprises: a seed catalyst;
the steps are as follows:
(1) Adding a seed catalyst prepared in advance into the adipic acid solution;
(2) The seed catalyst adsorbs solute molecules in the solution and provides a coacervation site that promotes the gradual formation of adipic acid crystals.
5. Filtration and washing:
materials: a filter membrane;
the device comprises: a filter membrane filter;
the steps are as follows:
(1) Filtering the solution through a filter membrane filter to separate adipic acid crystals;
(2) The adipic acid crystals were washed with cold water to remove impurities and solutes from the solution.
In the invention, by using the seed crystal catalyst, solute molecules can be effectively adsorbed, and a condensation place is provided to promote adipic acid crystals to be gradually formed, so that the purity of the product can be effectively improved, and the existence of impurities is reduced; the crystal formation rate and the crystal crystallinity can be increased by reasonably controlling the seed crystal treatment process, so that the yield and the product yield are improved; in the process of complex melting and purifying, the energy consumption and the cost of waste liquid treatment are reduced, and the raw material loss and the production of byproducts are reduced and the production benefit and the economic benefit are improved due to the repeated use of the seed crystal catalyst.
Through reasonable regulation and control of temperature and stirring speed, the formation of crystals can be more uniform and complete. Thereby obtaining adipic acid crystals with better quality and improving the quality of products; compared with the traditional purification and recrystallization method, the improved method has the advantages of simpler solution preparation, temperature control, seed crystal treatment and the like, and has relatively fewer steps and easier operation.
In conclusion, the adipic acid crystal re-crystallization method has the advantages of improving purity and crystal quality, simplifying process steps, improving yield and economy, solving the defects in the prior art, and having better practicability and economy.
In order to verify that the adipic acid complex melting, purifying and recrystallizing method of the embodiment of the invention has better purifying efficiency and crystal purity, the adipic acid crystal complex melting, purifying and recrystallizing method provided by the embodiment of the invention is illustrated by the following test examples.
Test examples
In this test example, adipic acid complex melting, purifying and recrystallizing methods provided in example 1 and example 2 were tested; the test method is as follows:
(1) Measurement of crystal formation time: the time elapsed from the completion of the preparation of the adipic acid solution to the completion of the crystal formation was recorded.
(2) Measurement of crystal purity: the purity of adipic acid crystals was measured using a spectrometer analytical method.
(3) Measurement of crystallinity: observing and evaluating the crystallinity of adipic acid crystals by using a microscopic method; scoring criteria: the diacid crystals observed under a microscope a complete hexagonal crystal structure with a crystallinity score of up to 10 points.
(4) Measurement of crystal yield: the yield of adipic acid crystals obtained from filtration and centrifugation from the adipic acid solution was recorded by weighing and counting.
Specific detection indexes are shown in table 1.
TABLE 1
According to the table 1, the adipic acid complex melting, purifying and recrystallizing methods provided by the examples 1 and 2 are adopted, the crystal formation time can be respectively completed within 1.5h and 2h, the crystal purity is up to 99.5%, and the yield is up to more than 85%; therefore, the adipic acid crystal re-crystallization method provided by the invention is an important factor affecting the yield efficiency, purity and yield of adipic acid crystals.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that the above-described embodiments and descriptions are only preferred embodiments of the present invention, and are not intended to limit the invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (8)
1. The method for re-crystallizing adipic acid crystals by means of complex melting, purification and re-crystallization is characterized by comprising the following steps:
s1, preparing seed crystals: pure adipic acid crystals are prepared to be used as seed crystals;
s2, preparing a solution: mixing adipic acid crystals to be redissolved and purified with a solvent, heating and stirring until the adipic acid crystals are completely dissolved to form an adipic acid solution;
s3, temperature control and stirring: in the process of re-melting, purifying and recrystallizing adipic acid, the temperature of the solution is 70-90 ℃, and the stirring speed is 200-500rpm;
s4, crystallization is formed: adding a seed catalyst to promote the formation of adipic acid crystals in adipic acid solution;
s5, filtering and washing: separating adipic acid crystals by using a filter medium to obtain adipic acid crystals after complex melting and purification.
2. The method for re-crystallizing adipic acid crystals by re-melting purification as claimed in claim 1, wherein: in the step S1, the pure adipic acid crystals are prepared as seed crystals by the following steps:
s1.1, mixing adipic acid and a solvent, heating and stirring until the adipic acid and the solvent are completely dissolved;
s1.2, filtering adipic acid solution through filter paper and a filter membrane;
s1.3, slowly cooling the filtered adipic acid solution to room temperature, wherein adipic acid gradually crystallizes to form crystals in the cooling process;
s1.4, separating the crystal from the solution by a filtering and centrifuging method, and filtering by using a filter membrane to obtain wet adipic acid crystals;
s1.5, washing wet adipic acid crystals by using a cold solvent, and drying the washed adipic acid crystals at a low temperature to obtain dry adipic acid crystals.
3. The method for re-crystallizing adipic acid crystals by re-melting purification as claimed in claim 1, wherein: in the step S2, the preparation steps of the adipic acid solution are as follows:
s2.1, preparing adipic acid crystals and a solvent, gradually adding the adipic acid crystals into the solvent, and stirring at the same time;
s2.2, continuously heating and stirring the mixture until adipic acid crystals are completely dissolved.
4. The method for re-crystallization of adipic acid crystals by re-melting purification according to claim 3, wherein: the solvent is one of water and an organic solvent, and the organic solvent adopts ethanol.
5. The method for re-crystallizing and purifying adipic acid crystals as claimed in claim 4, wherein: when the solvent is water, the water is preheated to 70-80 ℃.
6. The method for re-crystallizing adipic acid crystals by re-melting purification as claimed in claim 1, wherein: in the step S4, the seed crystal catalyst is selected from one of adipic acid crystal fragments, sodium diacid, triethylamine and pyridine.
7. The method for re-crystallizing adipic acid crystals by re-melting purification as claimed in claim 1, wherein: in S5, the steps of filtering and washing are as follows:
s5.1, filtering the solution through a filter medium to separate adipic acid crystals;
s5.2, washing adipic acid crystals by using cold water to remove impurities and solutes in the solution.
8. The method for re-crystallizing and purifying adipic acid crystals as claimed in claim 7, wherein: the filter medium selects one of filter paper, a filter funnel filtering mode and a filtering membrane filtering mode.
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