CN113773192B - Method for purifying dodecyl dicarboxylic acid by mixed extractant - Google Patents
Method for purifying dodecyl dicarboxylic acid by mixed extractant Download PDFInfo
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- CN113773192B CN113773192B CN202110980168.3A CN202110980168A CN113773192B CN 113773192 B CN113773192 B CN 113773192B CN 202110980168 A CN202110980168 A CN 202110980168A CN 113773192 B CN113773192 B CN 113773192B
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- -1 dodecyl dicarboxylic acid Chemical compound 0.000 title claims abstract description 77
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 35
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 90
- 238000001914 filtration Methods 0.000 claims abstract description 43
- 229960000583 acetic acid Drugs 0.000 claims abstract description 34
- 239000012065 filter cake Substances 0.000 claims abstract description 29
- 239000012528 membrane Substances 0.000 claims abstract description 28
- 239000013078 crystal Substances 0.000 claims abstract description 27
- 238000001728 nano-filtration Methods 0.000 claims abstract description 27
- 239000000919 ceramic Substances 0.000 claims abstract description 25
- 150000001335 aliphatic alkanes Chemical class 0.000 claims abstract description 18
- 239000000047 product Substances 0.000 claims abstract description 16
- 238000001035 drying Methods 0.000 claims abstract description 15
- 239000012362 glacial acetic acid Substances 0.000 claims abstract description 12
- 238000007670 refining Methods 0.000 claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 47
- 238000002425 crystallisation Methods 0.000 claims description 43
- 230000008025 crystallization Effects 0.000 claims description 43
- 239000002253 acid Substances 0.000 claims description 26
- 239000012535 impurity Substances 0.000 claims description 26
- 238000005406 washing Methods 0.000 claims description 24
- 238000004090 dissolution Methods 0.000 claims description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 14
- 239000000243 solution Substances 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 239000000498 cooling water Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 6
- 150000003839 salts Chemical class 0.000 claims description 6
- 239000011229 interlayer Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 238000004806 packaging method and process Methods 0.000 claims description 5
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 abstract description 18
- 239000000706 filtrate Substances 0.000 abstract description 5
- 238000004062 sedimentation Methods 0.000 description 15
- 239000012071 phase Substances 0.000 description 13
- 238000000746 purification Methods 0.000 description 13
- 238000000926 separation method Methods 0.000 description 12
- 239000012452 mother liquor Substances 0.000 description 9
- 239000012043 crude product Substances 0.000 description 8
- 239000010410 layer Substances 0.000 description 8
- 238000004821 distillation Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000012466 permeate Substances 0.000 description 7
- WMRCTEPOPAZMMN-UHFFFAOYSA-N 2-undecylpropanedioic acid Chemical compound CCCCCCCCCCCC(C(O)=O)C(O)=O WMRCTEPOPAZMMN-UHFFFAOYSA-N 0.000 description 6
- 238000003825 pressing Methods 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 238000000855 fermentation Methods 0.000 description 4
- 230000004151 fermentation Effects 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000008719 thickening Effects 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 235000013599 spices Nutrition 0.000 description 1
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Classifications
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- 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
-
- 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
-
- 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
- C07C51/47—Separation; Purification; Stabilisation; Use of additives by solid-liquid treatment; by chemisorption
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for purifying dodecyl dicarboxylic acid by using a mixed extractant, which comprises the steps of preparing C12 normal alkane and glacial acetic acid into the mixed extractant according to a certain proportion, dissolving a certain amount of crude dodecyl dicarboxylic acid into the mixed extractant under a proper temperature condition, filtering and purifying by using a nanofiltration ceramic membrane, cooling the purified filtrate according to a certain speed, separating out high-purity pure dodecyl dicarboxylic acid crystals, filtering and squeezing the mixed extractant and the high-purity pure dodecyl dicarboxylic acid crystals by using a high-pressure diaphragm plate frame, and drying a filter cake to obtain the dried high-purity pure dodecyl dicarboxylic acid crystals. The purity of the dodecyl dicarboxylic acid product obtained by the method is more than 99.5 percent, and the refining and purifying yield can reach more than 97.00 percent.
Description
Technical Field
The invention relates to the technical field of purification production of linear alkyl dicarboxylic acid, in particular to a method for purifying dodecyl dicarboxylic acid by using a mixed extractant.
Background
Dodecyl dicarboxylic acid is an industrial product with earlier development and larger yield, and is mainly used for synthesizing high polymer materials, spices, medicines and the like. The nylon synthesized by the straight-chain alkyl dicarboxylic acid has good mechanical properties, heat resistance, abrasion resistance, chemical resistance and self-lubricating property, is easy to process, can be processed into various plastic products, can be drawn into fibers, and can be further prepared into films, coatings, adhesives and the like. The method is widely used in the fields of automobiles, electronics, electrics, machinery, communication, military, aerospace and the like.
The dodecyl dicarboxylic acid produced by biological fermentation method contains impurities such as mycoprotein, pigment, various ions and the like in fermentation liquor, and the purity of the product is affected, so that the dodecyl dicarboxylic acid crude product needs to be purified.
The conventional single acetic acid purification technology is to prepare a dodecyl dicarboxylic acid product by dissolving a dodecyl dicarboxylic acid crude product obtained by fermentation with acetic acid, refining and purifying by recrystallization, decoloring and filtering, cooling and crystallizing, centrifugally separating, washing a filter cake, drying, recovering a solvent from a crystallization mother solution, and then distilling and purifying by a distillation tower for recycling. This original process requires a large-scale acetic acid distillation recovery unit and produces a large amount of intractable slag containing impurities and hetero acids.
The defect of single acetic acid purification technology is now adopted:
under the conditions of high acetic acid concentration and high temperature, the corrosion is severe, the equipment investment is large, the damage is quick, and the purification cost is high; the purification yield is low.
The solvent in the mother liquor is recovered by adopting a conventional distillation method, impurities in the mother liquor are accumulated, the temperature is increased, the mother liquor is thickened and degenerated continuously, and part of materials are carbonized. In addition to resulting in reduced recovery yields of byproducts.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for purifying dodecyl dicarboxylic acid by using a mixed extractant.
The invention is realized by the following technical scheme:
A process for purifying the lauryldicarboxylic acid by using mixed extractant includes such steps as proportionally mixing C12 n-alkane with glacial acetic acid, dissolving the crude lauryldicarboxylic acid in said mixed extractant, nano-filtering, purifying, cooling to obtain high-purity pure lauryldicarboxylic acid crystal, filtering, squeezing, and baking.
Preferably, the mixed extractant is prepared from C12 normal alkane and glacial acetic acid according to the volume ratio of (8.5-9.5): 1.
The invention adopts the mixed extractant prepared from C12 normal straight-chain alkane and glacial acetic acid according to a certain proportion, firstly realizes the purification effect of extraction, and realizes the crystallization purification in the subsequent crystallization process, and the two purification process effects are better than the conventional single acetic acid purification process, and the purity and quality of the product are higher.
Preferably, a nanofiltration ceramic membrane is used for filtering the mixed extractant dissolved with the crude dodecyl dicarboxylic acid to obtain purified permeate filtrate, and then the purified filtrate is cooled at a certain speed to separate out high-purity pure dodecyl dicarboxylic acid crystals.
The invention uses nanofiltration ceramic membrane to filter and dissolve the mixed extractant of the crude dodecyl dicarboxylic acid to obtain the purified filtrate filtered by the ceramic membrane, and then the purified filtrate is cooled according to a certain speed to separate out high-purity pure dodecyl dicarboxylic acid crystals. The nanofiltration ceramic membrane has higher filtration precision than a plate frame, and ensures the purity of the dodecyl dicarboxylic acid dissolved in the mixed extractant.
Preferably, a high-pressure diaphragm plate frame is used for filtering the precipitated pure dodecyl dicarboxylic acid crystals and the mixed extractant, pure water is used for top washing of filter cakes in the plate frame, then diaphragm pressure is used for squeezing the filter cakes, and finally the filter cakes are dried to obtain the dried pure dodecyl dicarboxylic acid crystals.
The invention uses the high-pressure diaphragm plate frame to filter and separate out pure dodecyl dicarboxylic acid crystals and mixed extractant, then uses pure water to top wash filter cakes, finally uses diaphragm pressure to squeeze filter cakes, dries the filter cakes to obtain the dried pure dodecyl dicarboxylic acid crystals, the high-pressure diaphragm plate frame has better solvent removal effect by squeezing, the pure water top washes the filter cakes, removes water-soluble impurities in the filter cakes, and improves the purity of dicarboxylic acid crystals.
Preferably, pure water of a top press filter cake is mixed in the mixed extractant filtered by the high-pressure diaphragm plate frame, and after standing, the mixed solution is layered, and C12 n-alkane and part of acetic acid are in an upper layer, water and part of acetic acid, impurities and mixed acid are in a bottom water phase; the upper C12 normal alkane and partial acetic acid do not contain salt and impurities, and are directly recycled to continue the production of the next batch.
The solvent recovery and reuse can be realized by a method of standing the mixed extractant, so that a distillation method for recovering pure acetic acid from acetic acid mother liquor is avoided, and the distillation mother liquor is prevented from rising along with the rising of the temperature, thickening and deterioration of the mother liquor and even carbonization; the new method reduces the production cost, saves energy and protects the environment.
Further preferred, a method for purifying dodecyl dicarboxylic acid by using a mixed extractant comprises the following steps:
firstly, preparing a mixed extractant: according to the volume ratio of 8.5-9.5: 1, mixing the C12 normal alkane and glacial acetic acid to form a mixed extractant.
Second, dissolving and filtering: adding a mixed extractant into a dissolution kettle to 70% -75% of the volume of the reaction kettle, starting stirring, starting a coil pipe and a jacket to heat to 90-95 ℃, dissolving 300-320 kg of crude dodecyl dicarboxylic acid in each 1m 3 of mixed extractant, and adding a proper amount of crude product for dissolution; and (3) heating the nanofiltration ceramic membrane system to 85-91 ℃, and filtering the mixed extractant solution in which the crude dodecyl dicarboxylic acid is dissolved.
Thirdly, crystallizing, filtering by a diaphragm plate frame, washing by pure water, and squeezing:
Opening cooling water in the interlayer of the crystallization kettle, regulating cooling water flow, reducing the temperature of the nanofiltration ceramic filtering solution to 20-30 ℃, and gradually separating out high-purity pure dodecyl dicarboxylic acid crystals until the crystallization is complete; filtering with high pressure diaphragm, collecting pure dodecyl dicarboxylic acid crystal in the frame, filtering with mixed extractant, separating, washing filter cake in the frame with pure water, and squeezing filter cake with diaphragm.
Fourthly, standing and layering the mixed extractant, and separating an upper mixed extractant, a lower water phase and other impurities and mixed acids in the upper mixed extractant and the lower water phase: the mixed extractant filtered out by the high-pressure diaphragm plate frame is mixed with pure water of the top press filter cake, and after standing, the mixed solution is layered, and the C12 normal alkane and part of glacial acetic acid are water and part of acetic acid, impurities and mixed acid in the upper layer water phase and the lower layer water phase; the upper C12 normal alkane and partial acetic acid do not contain salt and impurities, and are directly recycled to continue the production of the next batch.
Fifth step, drying and packaging: after the high-pressure diaphragm plate frame is intercepted, pure water is used for carrying out top washing, and then dodecyl dicarboxylic acid pure product crystals are squeezed by the diaphragm, and are dried by a conical vacuum spiral belt dryer to obtain qualified products, and the qualified products are packaged in a specification according to the requirements of customers.
Drying the filter cake to obtain refined dodecyl dicarboxylic acid; the refined and purified dodecyl dicarboxylic acid reaches the following technical indexes:
mono-acid: weight percent is more than or equal to 99.50 percent
Total acid: weight percent is more than or equal to 99.80 percent
Ash content: ppm is less than or equal to 15
Iron: ppm is less than or equal to 1 based on Fe 2O3
Total nitrogen: ppm is less than or equal to 15 based on N element
Moisture content: weight percent is less than or equal to 0.1
The refining and purifying yield of the dodecyl dicarboxylic acid is more than or equal to 97.00 percent.
The beneficial effects of the invention are as follows:
(1) A method for purifying dodecyl dicarboxylic acid by using mixed extractant is provided.
(2) The mixed extractant is adopted, one function is to realize the purification function of the extraction process, and the purification function of the crystallization process is realized in the subsequent crystallization process, and the two purification process effects are better than the conventional single acetic acid purification effect, so that the purity and quality of the product are higher.
(3) The nano-filtration ceramic membrane has higher filtration precision than a plate frame, so that the purity of the dodecyl dicarboxylic acid dissolved in the mixed extractant is ensured; and other dibasic acid and other impurities generated in the fermentation process are effectively removed.
(4) The high-pressure diaphragm plate and frame is used for squeezing, so that the high-pressure diaphragm plate and frame has obvious squeezing effect, better desolventizing effect, pure water is used for top washing of the filter cake, water-soluble impurities in the filter cake are removed, and the purity of dicarboxylic acid crystals of the rest filter cake is improved.
(5) The solvent recovery and reuse can be realized by a method of standing the mixed extractant, a method of recovering and using the acetic acid mother liquor for distillation is avoided, the distillation mother liquor is avoided along with the temperature rise, the concentration rise, the thickening and deterioration of the mother liquor and even carbonization are avoided, the yield rate is avoided to be reduced, the production cost is reduced by the novel method, and the energy is saved and the environment is protected.
Detailed Description
The invention will be further described in detail with reference to examples below:
Example 1
The invention relates to a method for purifying dodecyl dicarboxylic acid by using a mixed extractant, which comprises the following operation steps:
First step, preparing a mixed extractant
According to the volume ratio of 9:1, 9 parts of C12 normal alkane and 1 part of glacial acetic acid are mixed to form a mixed extractant.
Second step, dissolving and filtering
In a dissolution kettle, according to the proportion of 300-320 kg of crude dodecyl dicarboxylic acid in mixed extractant per 1m 3, dissolving the crude dodecyl dicarboxylic acid, and heating a nanofiltration membrane system after the dissolution is finished, and filtering the solution by using a nanofiltration ceramic membrane, wherein the method specifically comprises the following steps of:
S1: one-stage dissolution
Adding 22m 3 mixed extractant into a 30m 3 dissolution kettle, starting stirring, starting a coil pipe and a jacket to heat up to 95 ℃, adding 6600kg of crude product with 85% of dodecyl dicarboxylic acid for dissolution, and preserving heat for 45 minutes after the dissolution is finished.
S2: two-stage filtration
Heating the nanofiltration ceramic membrane system to 88 ℃; simultaneously opening a heating jacket valve of a crystallization kettle of 30m 3, and increasing the temperature in the crystallization kettle to 90 ℃; filtering the mixed extractant solution dissolved with the crude dodecyl dicarboxylic acid by using a nanofiltration ceramic membrane; collecting the permeate of the nanofiltration ceramic membrane to a crystallization kettle; after the permeate is submerged and stirred at the first level, the crystallization kettle is started to stir.
Third step, crystallization, membrane plate and frame filtration, pure water top washing and squeezing
S1: cooling crystallization
Slowly starting cooling water in an interlayer of the crystallization kettle, regulating cooling water flow, gradually reducing the temperature of the nanofiltration ceramic filtering solution to 30 ℃, and continuously separating out high-purity pure dodecyl dicarboxylic acid crystals along with the reduction of the temperature until the crystallization is complete; the whole cooling crystallization time is controlled to be 7 hours, and the cooling process is slow and then fast.
S2: diaphragm plate frame filtering, pure water top washing and squeezing
When the crystallization kettle finishes the crystallization process, filtering the completely crystallized material by using a high-pressure diaphragm plate frame, and intercepting pure dodecyl dicarboxylic acid crystals in the plate frame; the materials in the crystallization kettle are completely filtered, and 5m 3 pure water is used for top washing of the plate frame; finally, the filter cake is pressed by using a diaphragm, the pressing pressure is maintained at 1.2MP, the filter cake is pressed for 30 minutes, the top washing water and the filtered mixed extractant are mixed together, and the mixture is collected in a sedimentation separation tank.
And fourthly, standing and layering the mixed extractant, and separating an upper mixed extractant, a lower water phase, other impurities and mixed acid.
Slowly opening a cooling jacket of the sedimentation separation tank, cooling to below 15 ℃, carrying out sedimentation separation, maintaining the sedimentation time for 5 hours, layering the mixed solution, wherein the upper layer is C12 normal alkane and part of glacial acetic acid; lower aqueous phase and other impurities, miscellaneous acids; discharging the water phase and other impurities and the mixed acid from a bottom valve of the sedimentation separation tank; the upper C12 normal alkane and partial acetic acid do not contain salt and other impurities, and are directly recycled after being properly blended, so that the production of the next batch is continued.
Fifth step, drying and packaging
S1: after the high-pressure diaphragm plate frame is intercepted, pure water is used for top washing, a dodecyl dicarboxylic acid pure product crystal filter cake is pressed by a diaphragm, a conical vacuum spiral belt dryer is used for drying, the vacuum degree is-0.08 MP, the temperature is 85 ℃, the drying time is 3 hours, 5466Kg of refined dodecyl dicarboxylic acid is obtained, and the dodecyl dicarboxylic acid is packaged according to the specification of a customer.
The refined and purified dodecanedicarboxylic acid reaches the following technical indexes:
Mono-acid: wt% 99.51%
Total acid: wt% 99.86%
Ash content: ppm is less than or equal to 10
Iron: ppm is less than or equal to 0.5 based on Fe 2O3
Total nitrogen: ppm is less than or equal to 10 based on N element
Moisture content: wt% 0.1%
The refining and purifying yield of dodecanedicarboxylic acid is 97.29%.
Example 2.
The invention relates to a method for purifying dodecyl dicarboxylic acid by using a mixed extractant, which comprises the following operation steps:
First step, preparing a mixed extractant
According to the volume ratio of 8.5:1, 8.5 parts of C12 normal alkane and 1 part of glacial acetic acid are mixed to form a mixed extractant.
Second step, dissolving and filtering
In a dissolution kettle, according to the proportion of dissolving (300-320) kg of crude dodecyl dicarboxylic acid in the extractant mixed every 1m 3, the crude product is dissolved, the dissolution is finished, and meanwhile, the nanofiltration membrane system is heated, and the solution is filtered by using a nanofiltration ceramic membrane.
S1, one-stage dissolution
Adding 7m 3 mixed extractant into a 10m 3 dissolution kettle, starting stirring, starting a coil pipe and a jacket to heat up to 92 ℃, adding 2200kg of crude product with 80% of dodecyl dicarboxylic acid for dissolution, and preserving heat for 60 minutes after the dissolution is finished.
S2, two-stage filtration
Heating the nanofiltration ceramic membrane system to 85 ℃; opening a heating jacket valve of a 10m 3 crystallization kettle, and increasing the temperature in the crystallization kettle to 88 ℃; opening a nanofiltration ceramic membrane, and filtering a mixed extractant solution dissolved with a crude dodecyl dicarboxylic acid; collecting the permeate of the nanofiltration ceramic membrane to a crystallization kettle; after the permeate submerges the bottom stirring gear, stirring is started.
Third step, crystallization, membrane plate and frame filtration, pure water top washing and squeezing
S1, cooling crystallization
Slowly starting cooling water in an interlayer of the crystallization kettle, regulating cooling water flow, gradually reducing the temperature of the nanofiltration ceramic filtering solution to 28 ℃, and continuously separating out high-purity pure dodecyl dicarboxylic acid crystals along with the reduction of the temperature until the crystallization is complete; the whole cooling crystallization time is controlled to be 7 hours, and the cooling process is slow and then fast.
S2, membrane plate and frame filtration, pure water top washing and squeezing
After the crystallization kettle finishes the crystallization process, filtering the material with a high-pressure diaphragm plate frame, and intercepting pure dodecyl dicarboxylic acid crystals in the plate frame; the materials in the crystallization kettle are completely filtered, and 2m 3 pure water is used for top washing of the plate frame; finally, the filter cake is pressed by using a diaphragm, the pressing pressure is maintained at 1.0MP, the pressing is carried out for 30 minutes, the top washing water and the filtered mixed extractant are mixed together, and the mixture is collected in a sedimentation separation tank.
Fourth, standing and layering the mixed extractant, and separating out the upper mixed extractant, the lower water phase, other impurities and mixed acid
Slowly opening a cooling jacket of the sedimentation separation tank, cooling to below 12 ℃, carrying out sedimentation separation, maintaining the sedimentation time for 6 hours, layering the mixed solution, wherein the upper layer is C12 normal alkane and partial acetic acid; the lower layer is water phase and other impurities and mixed acid; discharging the water phase and other impurities and the mixed acid from a bottom valve of the sedimentation separation tank; the upper C12 normal alkane and partial acetic acid do not contain salt and other impurities, and are directly recycled after being properly blended, so that the production of the next batch is continued.
Fifth step, drying and packaging
After the high-pressure diaphragm plate frame is intercepted, pure water is used for top washing, a dodecyl dicarboxylic acid pure product crystal filter cake is pressed by a diaphragm, a conical vacuum spiral belt dryer is used for drying, the vacuum degree is-0.08 MP, the temperature is 83 ℃, the drying time is 3 hours, 1720Kg of refined dodecyl dicarboxylic acid is obtained, and the dodecyl dicarboxylic acid is packaged according to the specification of a customer.
The refined and purified dodecanedicarboxylic acid reaches the following technical indexes:
mono-acid: wt% 99.53%
Total acid: wt% 99.85%
Ash content: ppm is less than or equal to 10
Iron: ppm is less than or equal to 0.5 based on Fe2O3
Total nitrogen: ppm is less than or equal to 10 based on N element
Moisture content: wt% 0.1%
The refining and purifying yield of dodecanedicarboxylic acid is 97.58 percent.
Example 3.
The invention relates to a method for purifying dodecyl dicarboxylic acid by using a mixed extractant, which comprises the following operation steps:
First step, preparing a mixed extractant
According to the volume ratio of 9.5:1, 9.5 parts of C12 normal alkane and 1 part of glacial acetic acid are mixed to form a mixed extractant.
Second step, dissolving and filtering
In a dissolution kettle, according to the proportion of dissolving (300-320) kg of crude dodecyl dicarboxylic acid in the extractant mixed every 1m 3, the crude product is dissolved, the dissolution is finished, and meanwhile, the nanofiltration membrane system is heated, and the solution is filtered by using a nanofiltration ceramic membrane.
S1, one-stage dissolution
Adding 15m 3 mixed extractant into a 20m 3 dissolution kettle, starting stirring, starting a coil pipe and a jacket to heat up to 90 ℃, adding 4800kg of crude product with the dodecyl dicarboxylic acid content of 85.1 percent to dissolve, and preserving heat for 60 minutes after the dissolution is finished.
S2, two-stage filtration
Heating the nanofiltration ceramic membrane system to 91 ℃; opening a heating jacket valve of a 20m 3 crystallization kettle, and increasing the temperature in the crystallization kettle to 87 ℃; opening a nanofiltration ceramic membrane, and filtering a mixed extractant solution in which a crude dodecyl dicarboxylic acid is dissolved; collecting the permeate of the nanofiltration ceramic membrane to a crystallization kettle; after the permeate is submerged in the bottom baffle, stirring is started.
Third step, crystallization, membrane plate and frame filtration, pure water top washing and squeezing
S1, cooling crystallization
Slowly starting cooling water in an interlayer of the crystallization kettle, regulating cooling water flow, gradually reducing the temperature of the nanofiltration ceramic filtering solution to 29 ℃, and continuously separating out high-purity pure dodecyl dicarboxylic acid crystals along with the reduction of the temperature until the crystallization is complete; the whole cooling crystallization time is controlled to be 6.5 hours, and the cooling process is slow and fast.
S2, membrane plate and frame filtration, pure water top washing and squeezing
After the crystallization kettle finishes the crystallization process, filtering the material with a high-pressure diaphragm plate frame, and intercepting pure dodecyl dicarboxylic acid crystals in the plate frame; the materials in the crystallization kettle are completely filtered, and 3m 3 pure water is used for top washing of the plate frame; finally, the filter cake is pressed by using a diaphragm, the pressing pressure is maintained at 1.1MP, the pressing is carried out for 30 minutes, the top washing water and the filtered mixed extractant are mixed together, and the mixture is collected in a sedimentation separation tank.
And fourthly, standing and layering the mixed extractant, and separating an upper mixed extractant, a lower water phase, other impurities and mixed acid.
Slowly opening a cooling jacket of the sedimentation separation tank, cooling to below 11 ℃, carrying out sedimentation separation, maintaining the sedimentation time for 5.5 hours, layering the mixed solution, wherein the upper layer is C12 normal alkane and partial acetic acid; the lower layer is water phase and other impurities and mixed acid; discharging the water phase and other impurities and the mixed acid from a bottom valve of the sedimentation separation tank; the upper C12 normal alkane and partial acetic acid do not contain salt and other impurities, and are directly recycled after being properly blended, so that the production of the next batch is continued.
Fifth step, drying and packaging
After the high-pressure diaphragm plate frame is intercepted, pure water is used for top washing, a dodecyl dicarboxylic acid pure product crystal filter cake is pressed by a diaphragm, a conical vacuum spiral belt dryer is used for drying, the vacuum degree is-0.085 MP, the temperature is 80 ℃, the drying time is 3 hours, 3733Kg of refined dodecyl dicarboxylic acid is obtained, and the dodecyl dicarboxylic acid is packaged according to the specification of a customer.
The refined and purified dodecanedicarboxylic acid reaches the following technical indexes:
Mono-acid: wt% 99.55%
Total acid: wt% 99.85%
Ash content: ppm is less than or equal to 10
Iron: ppm is less than or equal to 0.5 based on Fe 2O3
Total nitrogen: ppm is less than or equal to 10 based on N element
Moisture content: wt% 0.1%
The refining and purifying yield of dodecanedicarboxylic acid is 97.35%.
Claims (1)
1. A method for purifying dodecyl dicarboxylic acid by using a mixed extractant is characterized in that: the method comprises the following steps:
firstly, preparing a mixed extractant: according to the volume ratio of 8.5-9.5: 1, mixing C12 normal alkane and glacial acetic acid to form a mixed extractant;
second, dissolving and filtering: adding a mixed extractant into a dissolution kettle to 70% -75% of the volume of the reaction kettle, starting stirring, starting a coil pipe and a jacket to heat to 90-95 ℃, dissolving 300-320 kg of crude dodecyl dicarboxylic acid in each 1m 3 of mixed extractant, and adding the crude dodecyl dicarboxylic acid into the dissolution kettle to dissolve; heating the nanofiltration ceramic membrane system to 85-91 ℃, and filtering the mixed extractant solution in which the crude dodecyl dicarboxylic acid is dissolved;
Thirdly, crystallizing, filtering by a diaphragm plate frame, washing by pure water, and squeezing:
opening cooling water in the interlayer of the crystallization kettle, regulating cooling water flow, reducing the temperature of the nanofiltration ceramic filtering solution to 20-30 ℃, and gradually separating out pure dodecyl dicarboxylic acid crystals until the crystallization is complete; filtering the completely crystallized material by using a high-pressure diaphragm plate frame, intercepting pure dodecyl dicarboxylic acid crystals in the plate frame, filtering and separating out mixed extractant, washing a filter cake in the plate frame with pure water, and squeezing the filter cake by using a diaphragm;
Fourth, the mixed extractant stands still for layering, and the upper mixed extractant, the lower water phase and other impurities in the upper mixed extractant are separated out: the mixed extractant filtered out by the high-pressure diaphragm plate frame is mixed with pure water of the top press filter cake, and after standing, the mixed solution is layered, and the upper water phase and the lower water phase of the C12 n-alkane and part of glacial acetic acid are water and part of acetic acid and impurities; the upper C12 normal alkane and partial acetic acid do not contain salt and impurities, and are directly recycled to continue the production of the next batch;
Fifth step, drying and packaging: after the high-pressure diaphragm plate frame is intercepted, pure water is used for carrying out top washing, and then dodecyl dicarboxylic acid pure product crystals are squeezed by the diaphragm and dried by a conical vacuum spiral belt dryer, so that a qualified product is obtained, and the qualified product is packaged according to the requirements of customers;
drying the filter cake to obtain refined dodecyl dicarboxylic acid; the refined and purified dodecyl dicarboxylic acid reaches the following technical indexes:
mono-acid: weight percent is more than or equal to 99.50 percent
Total acid: weight percent is more than or equal to 99.80 percent
Ash content: ppm is less than or equal to 15
Iron: ppm is less than or equal to 1 based on Fe 2O3
Total nitrogen: ppm is less than or equal to 15 based on N element
Moisture content: weight percent is less than or equal to 0.1
The refining and purifying yield of the dodecyl dicarboxylic acid is more than or equal to 97.00 percent.
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| CN103965035A (en) * | 2013-01-30 | 2014-08-06 | 上海凯赛生物技术研发中心有限公司 | Refining method of long-chain binary acid |
| CN104693018A (en) * | 2013-12-10 | 2015-06-10 | 上海凯赛生物技术研发中心有限公司 | Method for demulsifying and refining long-chain diacid fermentation broth |
| CN109824507A (en) * | 2019-02-20 | 2019-05-31 | 宁夏恒力生物新材料有限责任公司 | A kind of long-chain biatomic acid method of purification |
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| CN103965035A (en) * | 2013-01-30 | 2014-08-06 | 上海凯赛生物技术研发中心有限公司 | Refining method of long-chain binary acid |
| CN104693018A (en) * | 2013-12-10 | 2015-06-10 | 上海凯赛生物技术研发中心有限公司 | Method for demulsifying and refining long-chain diacid fermentation broth |
| CN109824507A (en) * | 2019-02-20 | 2019-05-31 | 宁夏恒力生物新材料有限责任公司 | A kind of long-chain biatomic acid method of purification |
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