CN114478342A - Dicumyl peroxide and crystallization method thereof - Google Patents
Dicumyl peroxide and crystallization method thereof Download PDFInfo
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- CN114478342A CN114478342A CN202011163986.6A CN202011163986A CN114478342A CN 114478342 A CN114478342 A CN 114478342A CN 202011163986 A CN202011163986 A CN 202011163986A CN 114478342 A CN114478342 A CN 114478342A
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- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 title claims abstract description 265
- 238000002425 crystallisation Methods 0.000 title claims abstract description 194
- 239000013078 crystal Substances 0.000 claims abstract description 358
- 230000008025 crystallization Effects 0.000 claims abstract description 143
- 238000001816 cooling Methods 0.000 claims abstract description 62
- 239000007788 liquid Substances 0.000 claims abstract description 62
- 238000000034 method Methods 0.000 claims abstract description 37
- 239000002904 solvent Substances 0.000 claims abstract description 33
- 238000000926 separation method Methods 0.000 claims abstract description 27
- 238000009826 distribution Methods 0.000 claims abstract description 23
- 238000009833 condensation Methods 0.000 claims abstract description 13
- 230000005494 condensation Effects 0.000 claims abstract description 13
- 238000011084 recovery Methods 0.000 claims abstract description 3
- 239000012452 mother liquor Substances 0.000 claims description 86
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 80
- 239000002245 particle Substances 0.000 claims description 50
- 239000000463 material Substances 0.000 claims description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 35
- RWGFKTVRMDUZSP-UHFFFAOYSA-N cumene Chemical compound CC(C)C1=CC=CC=C1 RWGFKTVRMDUZSP-UHFFFAOYSA-N 0.000 claims description 34
- 239000002002 slurry Substances 0.000 claims description 31
- 239000000203 mixture Substances 0.000 claims description 28
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 24
- 238000003756 stirring Methods 0.000 claims description 23
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 claims description 21
- 239000002826 coolant Substances 0.000 claims description 21
- 230000008569 process Effects 0.000 claims description 20
- ZOKCNEIWFQCSCM-UHFFFAOYSA-N (2-methyl-4-phenylpent-4-en-2-yl)benzene Chemical compound C=1C=CC=CC=1C(C)(C)CC(=C)C1=CC=CC=C1 ZOKCNEIWFQCSCM-UHFFFAOYSA-N 0.000 claims description 19
- VOOVDZMAQQVAEW-PFONDFGASA-N [(z)-2-methyl-4-phenylpent-3-en-2-yl]benzene Chemical compound C=1C=CC=CC=1C(/C)=C\C(C)(C)C1=CC=CC=C1 VOOVDZMAQQVAEW-PFONDFGASA-N 0.000 claims description 18
- FRIBMENBGGCKPD-UHFFFAOYSA-N 3-(2,3-dimethoxyphenyl)prop-2-enal Chemical compound COC1=CC=CC(C=CC=O)=C1OC FRIBMENBGGCKPD-UHFFFAOYSA-N 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 16
- 238000012216 screening Methods 0.000 claims description 14
- 239000012141 concentrate Substances 0.000 claims description 11
- 239000002178 crystalline material Substances 0.000 claims description 8
- 239000003607 modifier Substances 0.000 claims description 8
- 229920000642 polymer Polymers 0.000 claims description 6
- 238000001953 recrystallisation Methods 0.000 claims description 3
- OAMAKKTXAPRVDG-UHFFFAOYSA-N (4,6-dimethyl-2,6-diphenylhept-1-en-4-yl)benzene Chemical compound C=1C=CC=CC=1C(C)(C)CC(C)(C=1C=CC=CC=1)CC(=C)C1=CC=CC=C1 OAMAKKTXAPRVDG-UHFFFAOYSA-N 0.000 claims description 2
- ICLPNZMYHDVKKI-UHFFFAOYSA-N 1,1,3-trimethyl-3-phenyl-2h-indene Chemical compound C12=CC=CC=C2C(C)(C)CC1(C)C1=CC=CC=C1 ICLPNZMYHDVKKI-UHFFFAOYSA-N 0.000 claims description 2
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 2
- 238000010583 slow cooling Methods 0.000 claims 1
- 239000000243 solution Substances 0.000 abstract description 46
- 238000004581 coalescence Methods 0.000 abstract description 34
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 239000010413 mother solution Substances 0.000 abstract description 10
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 230000001276 controlling effect Effects 0.000 description 12
- 230000009467 reduction Effects 0.000 description 12
- 239000010410 layer Substances 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- 238000002156 mixing Methods 0.000 description 8
- 238000011160 research Methods 0.000 description 5
- 239000012595 freezing medium Substances 0.000 description 3
- 230000001788 irregular Effects 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 239000004417 polycarbonate Substances 0.000 description 3
- 229920000515 polycarbonate Polymers 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- WXMKPNITSTVMEF-UHFFFAOYSA-M sodium benzoate Chemical compound [Na+].[O-]C(=O)C1=CC=CC=C1 WXMKPNITSTVMEF-UHFFFAOYSA-M 0.000 description 3
- 239000012267 brine Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 235000010234 sodium benzoate Nutrition 0.000 description 2
- 239000004299 sodium benzoate Substances 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 244000043261 Hevea brasiliensis Species 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920003052 natural elastomer Polymers 0.000 description 1
- 229920001194 natural rubber Polymers 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920013716 polyethylene resin Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C407/00—Preparation of peroxy compounds
- C07C407/003—Separation; Purification; Stabilisation; Use of additives
Abstract
The invention discloses dicumyl peroxide and a crystallization method thereof. The crystallization method comprises the following steps: carrying out first cooling crystallization and solid-liquid separation on a condensation concentrated solution containing dicumyl peroxide and a crystallization solvent in a crystallizer I to obtain a dicumyl peroxide crystal I and a crystallization mother solution I, carrying out second cooling crystallization and solid-liquid separation on the crystallization mother solution I in a crystallizer II to obtain a dicumyl peroxide crystal II and a crystallization mother solution II, carrying out solvent recovery and concentration on the crystallization mother solution II to obtain a mother solution concentrated solution, and carrying out third cooling crystallization and solid-liquid separation on all or part of the mother solution concentrated solution and the crystallization solvent in a crystallizer III to obtain a dicumyl peroxide crystal III and a crystallization mother solution III. The method can produce dicumyl peroxide with high quality, high purity, regular and transparent crystal shape, no crystal occlusion and coalescence, uniform crystal size distribution, high yield of large-grain crystal, and low production energy consumption.
Description
Technical Field
The invention relates to dicumyl peroxide and a crystallization method thereof.
Background
Dicumyl peroxide is a strong oxidant, DCP for short, is mainly used as a vulcanizing agent of natural rubber and synthetic rubber, an initiator of polymerization reaction, a polyethylene resin crosslinking agent and the like, and is widely used in industries of shoe making, wires and cables, building material rubber and the like.
At present, the dicumyl peroxide is mainly produced by a batch crystallization method, and the problems comprise that: the product quality is poor, for example, the crystal size distribution is not uniform, the fine powder is more, the yield of the large-grained crystal is low, the crystal agglomeration is serious, the shape is irregular, the crystal transparency is not high, the interior is occluded, and the like.
CN102367234A discloses a dicumyl peroxide crystallization method, which uses distilled water instead of alcohol as crystallization solvent to simplify the process flow, but water is a poor crystallization solvent for dicumyl peroxide, and therefore, is not used in practical production.
CN102367235A discloses a method for crystallizing dicumyl peroxide, which uses alcohol as a crystallization solvent, controls the temperature of a freezing medium by a secondary freezing method, further ensures that the temperature difference between the temperature in a kettle and the freezing medium is small, and increases the yield of granular crystals by adding seed crystals. CN202315388U discloses a dicumyl peroxide crystallization device, which controls the temperature of freezing medium brine through a brine buffer tank, a heater and a cooler, further controls the temperature in the crystallization process, and increases the yield of large-particle size crystals by adding seed crystals. Both of the above two patents control the heat transfer temperature difference by controlling the temperature of the cooling medium, so as to realize the precise control of the temperature in the crystallization process, and then improve the yield of the large-grained crystals by assisting the method of adding the seed crystals. However, in the crystallization process, the generation of fine crystals is inevitable no matter how the temperature difference of heat transfer, the crystallization temperature, and the addition of the seed crystal are controlled, and the above two methods or apparatuses can only reduce the generation of fine crystals to some extent, so that the improvement of the yield of crystals having a large particle size is limited.
CN203833848U discloses a dicumyl peroxide continuous crystallization system, which improves the efficiency of the crystallization process by continuous crystallization and eliminates fine crystals by mother liquor overflow to improve the uniformity of crystal size distribution. The method mainly realizes the elimination of fine crystals by crystallization equipment, but in the method, only the part of fine crystals overflowing along with the crystallization mother liquor can be eliminated, and the part of fine crystals still existing in the crystallizer are not overflowed along with the crystallization mother liquor and cannot be eliminated, so the method has limited effect on improving the uniformity of the product particle size distribution. In addition, the crystallizer needs to accurately control the overflow of the crystallization mother liquor, so that most fine crystals overflow along with the crystallization mother liquor, and the overflow of product crystals is avoided, thereby having certain operation difficulty.
In summary, the existing dicumyl peroxide crystallization methods still need further improvement to improve the product quality, increase the yield of large-particle size crystals and reduce the production energy consumption.
Disclosure of Invention
The invention aims to solve the technical problems of poor product quality, irregular crystal shape, poor transparency, serious crystal occlusion and coalescence, uneven crystal particle size distribution, low large-particle-size crystal yield and high production energy consumption in the existing dicumyl peroxide production method, and provides a novel dicumyl peroxide crystallization method which can produce dicumyl peroxide with high quality, high purity, regular crystal shape, transparency, no crystal occlusion and coalescence, even crystal particle size distribution and high large-particle-size crystal yield and has low production energy consumption.
The invention provides a method for crystallizing dicumyl peroxide, which comprises the following steps:
a) carrying out first cooling crystallization on the condensation concentrated solution containing dicumyl peroxide and a crystallization solvent in a crystallizer I to obtain crystal slurry I containing dicumyl peroxide crystals;
b) carrying out solid-liquid separation on the crystal slurry I to obtain a dicumyl peroxide crystal I and a crystallization mother liquor I, and washing, drying and screening the dicumyl peroxide crystal I to obtain a dicumyl peroxide crystal product I;
c) carrying out second cooling crystallization on the crystallization mother liquor I in a crystallizer II to obtain crystal slurry II containing dicumyl peroxide crystals;
d) carrying out solid-liquid separation on the crystal slurry II to obtain a dicumyl peroxide crystal II and a crystallization mother liquor II, and washing, drying and screening the dicumyl peroxide crystal II to obtain a dicumyl peroxide crystal product II;
e) carrying out solvent recovery and concentration on the crystallization mother liquor II to obtain mother liquor concentrated solution, and carrying out third cooling crystallization on all or part of the mother liquor concentrated solution and the crystallization solvent in a crystallizer III to obtain crystal slurry III containing dicumyl peroxide crystals;
f) and (3) carrying out solid-liquid separation on the crystal slurry III to obtain a dicumyl peroxide crystal III and a crystallization mother liquor III, and carrying out solvent recrystallization, washing, drying and screening on all or part of the dicumyl peroxide crystal III to obtain a dicumyl peroxide crystal product III.
According to some embodiments of the crystallization method of the present invention, the crystallization method further comprises adding a crystal habit modifier to the crystallizer I.
According to some embodiments of the crystallization method of the present invention, the crystallization habit modifier is selected from at least one of 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene, 1, 3-trimethyl-3-phenylindane and 2,4, 6-triphenyl-4, 6-dimethyl-1-heptene, a polymer of α -methylstyrene and a polymer of α -methylstyrene, and more preferably at least one of polymer V-276, polymer M-80 and sodium benzoate. In the present invention, the crystal habit modifier can be obtained commercially.
According to some embodiments of the crystallization method of the present invention, the crystal habit modifier is added in an amount of 0.01 to 5% by weight of the condensed concentrate. Such as 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 1%, 2%, 3%, 4%, 5%, and any value therebetween.
According to some preferred embodiments of the crystallization process according to the invention, the crystallization process further comprises in step e) concentrating a portion of the mother liquor back into crystallizer I.
According to some preferred embodiments of the crystallization method of the present invention, the amount of partial mother liquor concentrate returned to the crystallizer I is such that the weight ratio of the condensed concentrate to the mother liquor concentrate is 1 to 10:1, more preferably 1 to 3: 1.
According to some preferred embodiments of the crystallization process according to the invention, part of the mother liquor is concentrated back to the crystallizer I in such an amount that the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is between 0.1 and 5: 1.
According to some preferred embodiments of the crystallization method according to the invention, the crystallization method further comprises returning part of the dicumyl peroxide crystals III to the crystallizer I in step f).
According to some preferred embodiments of the crystallization method of the present invention, a part of the dicumyl peroxide crystals III is returned to the crystallizer I in an amount such that the weight ratio of the condensation concentrate to the dicumyl peroxide crystals III is 5-20: 1.
According to some preferred embodiments of the crystallization method according to the invention, part of the dicumyl peroxide crystals III is returned to the crystallizer I in such an amount that the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is between 0.1 and 5: 1.
According to some preferred embodiments of the crystallization method of the present invention, the crystallization method further comprises: and adding seed crystals in the processes of the first cooling crystallization, the second cooling crystallization and the third cooling crystallization independently.
According to some embodiments of the crystallization method of the present invention, the seed crystal is dicumyl peroxide crystal. Preferably, the grain size of the seed crystal is 425-710 μm. Preferably, the purity of the seed crystal is more than or equal to 99.5 percent. More preferably, the dicumyl peroxide crystals are regular transparent, free of occlusions and agglomerates.
According to some preferred embodiments of the crystallization method of the present invention, the seed crystal is added in an amount of 0.5 to 10% by weight based on the total weight of the dicumyl peroxide crystalline material in the crystallizer before seed crystal addition.
According to some preferred embodiments of the crystallization method of the present invention, the seed crystal is added at 0.1 to 0.5 ℃ above the crystallization saturation temperature.
According to some preferred embodiments of the crystallization method of the present invention, after the seed crystal is added, the seed crystal is maintained at a constant temperature for a period of time, and then a slow-to-fast cooling mode is adopted for the crystallizer; more preferably, the cooling rate is 0.1-3 ℃/h before the liquid-liquid two-phase layering disappears, the cooling rate is 1-10 ℃/h after the liquid-liquid two-phase layering disappears, and the cooling rate is greater than the cooling rate before the liquid-liquid two-phase layering disappears after the liquid-liquid two-phase layering disappears.
According to some preferred embodiments of the crystallization method of the present invention, the temperature difference between the material in the crystallizer and the cooling medium is controlled to be less than or equal to 10 ℃, more preferably less than or equal to 5 ℃ during the crystallization process of the crystallizer.
According to some preferred embodiments of the crystallization method of the present invention, the concentration of dicumyl peroxide in the condensed and concentrated solution containing dicumyl peroxide is 80 to 95 wt%.
According to some preferred embodiments of the crystallization method of the present invention, a ratio of a total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to a total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 5 to 20: 1.
According to some preferred embodiments of the crystallization method of the present invention, the concentration of dicumyl peroxide in the mother liquor concentrate is 70 to 85% by weight, and preferably, the purity of dicumyl peroxide crystal III is 85 to 99%.
According to some preferred embodiments of the crystallization method of the present invention, the crystallization solvent is ethanol or methanol.
According to some preferred embodiments of the crystallization method of the present invention, the crystallization solvent is a mixture of ethanol and water having a water content of 5 to 15% by weight.
According to some preferred embodiments of the crystallization method of the present invention, the crystallization solvent is a mixture of methanol and water having a water content of 5 to 10% by weight.
According to some preferred embodiments of the crystallization method of the present invention, the ratio of the weight of the mixture of ethanol and water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 0.5 to 1: 1. Such as 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, and any value in between.
According to some preferred embodiments of the crystallization method of the present invention, the ratio of the weight of the mixture of methanol and water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 0.6 to 1.2: 1. Such as 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, and any value in between.
According to some preferred embodiments of the crystallization method of the present invention, the stirring blades of the crystallizer I, the crystallizer II and the crystallizer III are each independently of the other a double-layer combination, more preferably a combination of a four-blade open turbine and a frame paddle. Such as shown in fig. 7.
According to some preferred embodiments of the crystallization method of the present invention, the solid-to-liquid ratio in the crystallizer I, the crystallizer II and the crystallizer III is 0.4 to 0.8:1, respectively and independently. Such as 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, and any value in between.
According to some preferred embodiments of the crystallization method of the present invention, the temperature of the first cooling crystallization is 15 ℃ to 20 ℃.
According to some preferred embodiments of the crystallization method of the present invention, the temperature of the second cooling crystallization is from-5 ℃ to 5 ℃.
According to some preferred embodiments of the crystallization method of the present invention, the temperature of the third cooling crystallization is from-10 ℃ to 5 ℃.
According to some preferred embodiments of the crystallization method of the present invention, the recrystallization, washing, drying, and sieving may be conventional operations and methods in the art, and will not be described herein.
In a second aspect, the present invention provides dicumyl peroxide prepared by the above crystallization method.
According to some preferred embodiments of the dicumyl peroxide according to the present invention, the dicumyl peroxide is in the form of a flake or a solid.
In the present invention, the dicumyl peroxide may be at least one of dicumyl peroxide crystal product I, dicumyl peroxide crystal product II and dicumyl peroxide crystal product III.
According to some preferred embodiments of dicumyl peroxide according to the present invention, the purity of dicumyl peroxide is 99.8% or more.
According to some preferred embodiments of dicumyl peroxide according to the present invention, the dicumyl peroxide has a uniform crystal size distribution.
According to some preferred embodiments of dicumyl peroxide according to the present invention, in the dicumyl peroxide, the weight ratio of crystals having a particle size of 850 μm or more to the total weight of the crystals is 95% or more.
According to some preferred embodiments of dicumyl peroxide of the present invention, the dicumyl peroxide has a bulk density of 0.6 to 0.7g/cm3。
The invention has the beneficial effects that:
(1) research on crystallization kinetics shows that dicumyl peroxide crystals grow faster in the initial stage and grow slower in the later stage, and fine powder tends to increase, so that the conventional common crystallization method is divided into two stages according to the growth rate of the crystals, preferably, a proper solid-liquid ratio is controlled, the crystals with good crystal forms are taken out in time to serve as products, and further abrasion is avoided to cause crystal breakage or increase of fine powder.
(2) The research on the crystal morphology discovers that the growth rate of each growth surface of the dicumyl peroxide crystal can be remarkably regulated by mixing the condensation concentrated solution and the mother solution concentrated solution or the condensation concentrated solution and the crystal crystals of the mother solution concentrated solution and a specific crystal habit regulating agent, so that the crystal habit can be regulated from a flake shape to a three-dimensional shape, and the phenomena of crystal occlusion and coalescence are effectively avoided.
(3) Through researches, the conventional method for adding the seed crystal below the saturation temperature can not effectively eliminate fine grains, and the seed crystal is added in a proper temperature range above the saturation temperature, so that the fine grains can be effectively reduced.
(4) Through the research of crystallization thermodynamics, the mixed solvent of alcohol and water is found to be adopted, so that the transparency of the crystal product can be obviously improved, but the liquid-liquid layering phenomenon can occur in the crystallization process, and the fine powder can be effectively eliminated only by adopting a proper cooling rate before the liquid-liquid layering disappears.
(5) Research on a crystallization flow field shows that the stirring blade has a remarkable influence on generation of fine powder, and the double-layer combined blade can effectively reduce generation of the fine powder.
(6) The crystallization method of dicumyl peroxide obviously reduces the coalescence of crystals, improves the product quality, ensures that the obtained crystals are regular and transparent, and has no occlusion and coalescence, improves the uniformity of the particle size distribution of the crystals, improves the yield of the crystals with large particle size, reduces the production energy consumption, and obtains better technical effects.
Drawings
FIG. 1 is a schematic flow chart of a process for crystallizing dicumyl peroxide according to example 1 of the present invention;
FIG. 2 is a photomicrograph of dicumyl peroxide provided in example 1 of the present invention;
FIG. 3 is a photomicrograph of dicumyl peroxide provided in example 9 of the present invention;
FIG. 4 is a photomicrograph of dicumyl peroxide provided in comparative example 1;
FIG. 5 is a photomicrograph of dicumyl peroxide provided in example 4 of the present invention;
FIG. 6 is a photomicrograph of dicumyl peroxide provided in example 10 of the present invention;
fig. 7 is a schematic view of a double-layer combined blade of a four-folded-blade open turbine and a frame paddle provided in embodiment 1 of the present invention;
fig. 8 is a schematic view of a prior art blade of example 10.
Detailed Description
In order that the present invention may be more readily understood, the following detailed description of the invention is given by way of example only, and is not intended to limit the scope of the invention.
[ example 1 ] A method for producing a polycarbonate
As described in fig. 1. 1600g of dicumyl peroxide condensed concentrated solution (the content of DCP is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 700g of mother liquor concentrated solution and 1300g of a mixture of ethanol and water (the content of ethanol is 92 wt%) are added into a crystallizer I, a double-layer combined paddle of a four-fold-blade open turbine and a frame paddle (shown in figure 7) is adopted for stirring and mixing uniformly, the temperature is raised until the solid is completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5% of the total weight of the dicumyl peroxide crystalline material in the crystallizer I, growing crystals for 30min, then continuously reducing the temperature of the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 3 ℃, the temperature reduction rate to be 1 ℃/h, and after liquid in the crystallizer is layered and disappears, adjusting the temperature reduction rate to be 2 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, carrying out solid-liquid separation on crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1, thus obtaining dicumyl peroxide crystals I and crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a transparent stereoscopic dicumyl peroxide crystal product I with a regular shape and no occlusion and coalescence, and a microscopic picture is shown in figure 2, wherein the purity is 99.93%, the crystal granularity is uniformly distributed, and the weight of crystals with the grain size of more than or equal to 850 mu m accounts for 99.1% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II to be continuously cooled and crystallized, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as that of the crystallizer I, 5 percent of dicumyl peroxide seed crystal (the average particle size is 600 mu m, the purity is more than or equal to 99.5 percent) of the total weight of dicumyl peroxide crystallization materials in the crystallizer II is added to carry out crystal growth for 20min, then the crystallizer is cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 4 ℃, the cooling rate is 1.5 ℃/h, when the temperature is reduced to 5 ℃, solid-liquid separation is carried out on a crystal slurry II containing the dicumyl peroxide crystal II, the solid-liquid ratio in the crystallizer III is 0.6:1, a dicumyl peroxide crystal II and a crystallization mother liquor II are obtained, the dicumyl peroxide crystal II is washed, dried and screened to obtain a solid dicumyl peroxide crystal product II with a regular shape, transparency, no inclusion and no coalescence, the microscopic photograph is similar to that in FIG. 2, the purity is 99.9%, the crystal size distribution is uniform, wherein the weight of the crystal with the grain size of more than or equal to 850 μm accounts for 98% of the total weight of the crystal. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 80 wt%), returning part of the mother liquor concentrated solution to the crystallizer I (the amount of the part of the mother liquor concentrated solution returned to the crystallizer I meets the weight ratio of the condensation concentrated solution to the mother liquor concentrated solution is 2:1, leading the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene to be 2:1), adding the rest of the mixture of ethanol and water (the ethanol content is 92 wt%, the weight ratio of the mixture of the ethanol and the water to the weight of the crystallization material containing the dicumyl peroxide in the crystallizer is 1:1) into the crystallizer III for cooling and crystallizing, cooling to 0.1 ℃ above the saturation temperature by using a stirring blade same as the crystallizer I, adding dicumyl peroxide crystal seeds (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) accounting for 5% of the total weight of dicumyl peroxide crystal materials in the crystallizer III, growing crystals for 15min, cooling the crystallizer, controlling the temperature difference between the materials in the crystallizer and a cooling medium to be 5 ℃, the cooling rate to be 2 ℃/h, cooling to-10 ℃, carrying out solid-liquid separation on crystal slurry III containing dicumyl peroxide crystals III, wherein the solid-liquid ratio in the crystallizer III is 0.7:1 to obtain dicumyl peroxide crystals III and a crystallization mother solution III, recrystallizing the dicumyl peroxide crystals III by using a crystallization solvent, washing, drying and screening to obtain a solid dicumyl peroxide crystal product III which is regular in shape, transparent, free of occlusion and coalescence, wherein a microscopic photograph is similar to that shown in a figure 2, the purity is 99.6 percent, the crystal granularity is evenly distributed, wherein the weight of the crystal with the grain diameter of more than or equal to 850 mu m accounts for 96 percent of the total weight of the crystal.
[ example 2 ]
The process of example 1 is followed except that the mother liquor concentrate is not returned to crystallizer I, but rather a portion of dicumyl peroxide crystals III is returned to crystallizer I, specifically:
1600g of dicumyl peroxide condensed concentrated solution (the content of DCP is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 1300g of a mixture of ethanol and water (the content of ethanol is 92 wt%) is added into a crystallizer I, a four-folding-blade open turbine and a double-layer combined blade of a frame paddle are adopted for stirring and mixing uniformly, the temperature is raised until the solid is completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5% of the total weight of the dicumyl peroxide crystalline material in the crystallizer I, growing crystals for 30min, then continuously reducing the temperature of the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 3 ℃, the temperature reduction rate to be 1 ℃/h, and after liquid in the crystallizer is layered and disappears, adjusting the temperature reduction rate to be 2 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, performing solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1 to obtain dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a transparent stereoscopic dicumyl peroxide crystal product I with a regular shape and no occlusion and coalescence, and a microscopic picture is similar to that shown in a figure 2, the purity is 99.94%, the crystal granularity is uniformly distributed, and the weight of crystals with the grain size of more than or equal to 850 mu m accounts for 99.2% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II to be continuously cooled and crystallized, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as that of the crystallizer I, 5 percent of dicumyl peroxide seed crystal (the average particle size is 600 mu m, the purity is more than or equal to 99.5 percent) of the total weight of dicumyl peroxide crystallization materials in the crystallizer II is added to carry out crystal growth for 20min, then the crystallizer is cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 4 ℃, the cooling rate is 1.5 ℃/h, when the temperature is reduced to 5 ℃, solid-liquid separation is carried out on a crystal slurry II containing the dicumyl peroxide crystal II, the solid-liquid ratio in the crystallizer II is 0.6:1, the dicumyl peroxide crystal II and the crystallization mother liquor II are obtained, the dicumyl peroxide crystal II is washed, dried and screened to obtain a solid dicumyl peroxide crystal product II with a regular shape, transparency, no inclusion and no coalescence, the microphotograph is similar to that of FIG. 2, the purity is 99.8%, the crystal size distribution is uniform, and the weight of the crystal with the particle size of 850 μm or more accounts for 97% of the total weight of the crystal. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 78 weight percent), adding all mother liquor concentrated solution, a mixture of ethanol and water (the content of the ethanol is 92 weight percent, the ratio of the weight of the mixture of the ethanol and the water to the weight of the crystallization material containing the dicumyl peroxide in the crystallizer is 0.8:1) into a crystallizer III for cooling crystallization, adopting a stirring paddle which is the same as that of the crystallizer I, when the temperature is reduced to be 0.1 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5 percent) of the dicumyl peroxide seed crystals accounting for 5 percent of the total weight of the dicumyl peroxide crystallization material in the crystallizer III, growing crystals for 15min, then cooling the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 5 ℃, the cooling rate is 2 ℃/h, when the temperature is reduced to-10 ℃, solid-liquid separation is carried out on a crystal slurry III containing dicumyl peroxide crystals III, the solid-liquid ratio in a crystallizer III is 0.6:1, the dicumyl peroxide crystals III and a crystallization mother liquor III are obtained, wherein part of the dicumyl peroxide crystals III return to the crystallizer I, part of the dicumyl peroxide crystals III (the purity is 95%) return to the crystallizer I (the weight ratio of the condensation concentrated solution to the dicumyl peroxide crystals III is 10:1, the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene and the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2 are obtained by returning part of the dicumyl peroxide crystals III to the crystallizer I, the ratio of the total concentration of the 4-diphenyl-4-methyl-2-pentene is 2:1), the rest dicumyl peroxide crystal III is recrystallized by a crystallization solvent, washed, dried and screened to obtain a transparent, non-occluded and coalesced three-dimensional dicumyl peroxide crystal product III, the microscopic picture of the product III is similar to that shown in the figure 2, the purity is 99.5 percent, the crystal granularity is uniformly distributed, and the weight of the crystal with the grain diameter of more than or equal to 850 mu m accounts for 95 percent of the total weight of the crystal.
[ example 3 ]
According to the method of the embodiment 1, the difference is that the mother liquor concentrated solution is not returned to the crystallizer I, but the crystal habit modifier is added into the crystallizer I, and the concrete steps are as follows:
1600g of dicumyl peroxide condensed concentrated solution (the DCP content is 91 wt percent, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 16g of sodium benzoate (CAS number is 532-32-1), 1300g of a mixture of ethanol and water (the ethanol content is 92 wt percent) are added into a crystallizer I, a four-folding-blade open turbine and a double-layer combined blade of a frame type paddle are adopted for stirring and mixing uniformly, the temperature is raised until the solid is completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5% of the total weight of the dicumyl peroxide crystalline material in the crystallizer I, growing crystals for 10min, then continuously reducing the temperature of the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 3 ℃, the temperature reduction rate to be 1 ℃/h, and after liquid in the crystallizer is layered and disappears, adjusting the temperature reduction rate to be 2 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, carrying out solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1, thus obtaining dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a transparent stereoscopic dicumyl peroxide crystal product I with a regular shape and no occlusion and coalescence, and a microscopic picture is similar to that shown in figure 2, the purity is 99.92%, the crystal granularity is uniformly distributed, and the weight of crystals with the grain size of more than or equal to 850 mu m accounts for 99% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II to be continuously cooled and crystallized, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as that of the crystallizer I, 5 percent of dicumyl peroxide seed crystal (the average particle size is 600 mu m, the purity is more than or equal to 99.5 percent) of the total weight of dicumyl peroxide crystallization materials in the crystallizer II is added to carry out crystal growth for 5min, then the crystallizer is cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 4 ℃, the cooling rate is 1.5 ℃/h, when the temperature is reduced to 5 ℃, solid-liquid separation is carried out on a crystal slurry II containing the dicumyl peroxide crystal II, the solid-liquid ratio in the crystallizer II is 0.6:1, the dicumyl peroxide crystal II and the crystallization mother liquor II are obtained, the dicumyl peroxide crystal II is washed, dried and screened to obtain a solid dicumyl peroxide crystal product II with a regular shape, transparency, no inclusion and no coalescence, the microphotograph is similar to that of FIG. 2, the purity is 99.7%, the crystal size distribution is uniform, and the weight of the crystal with the particle size of 850 μm or more accounts for 96% of the total weight of the crystal. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 82 wt%), adding the mixture of all the mother liquor concentrated solution, ethanol and water (the content of the ethanol is 92 wt%, the ratio of the weight of the mixture of the ethanol and the water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 0.5: 1) into a crystallizer III (a stirring blade same as the crystallizer I) to perform a cooling crystallization process, cooling to 0.1 ℃ above the saturation temperature by using the stirring blade same as the crystallizer I, adding dicumyl peroxide crystal seeds (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5% of the total weight of the dicumyl peroxide crystallization material in the crystallizer III, growing crystals for 15min, cooling the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 5 ℃, the cooling rate is 2 ℃/h, when the temperature is reduced to-10 ℃, solid-liquid separation is carried out on a crystal slurry III containing dicumyl peroxide crystals III, the solid-liquid ratio in a crystallizer III is 0.6:1, the dicumyl peroxide crystals III and a crystallization mother liquor III are obtained, wherein part of the dicumyl peroxide crystals III return to a crystallizer I, the dicumyl peroxide crystals III are recrystallized by a crystallization solvent, washed, dried and screened to obtain a solid dicumyl peroxide crystal product III which is regular in shape, transparent, free of occlusion and coalescence, a microscopic picture is similar to that shown in figure 2, the purity is 99.4%, the crystal granularity is uniformly distributed, and the weight of crystals with the grain size of more than or equal to 850 mu m accounts for 94% of the total weight of the crystals.
[ example 4 ]
According to the method of the embodiment 1, the difference is that the constant temperature is maintained for a period of time after the seed crystal is added, and then the crystallizer is cooled in a fast-first and slow-second mode, which specifically comprises the following steps:
1600g of dicumyl peroxide condensed concentrated solution (the content of DCP is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 700g of mother liquor concentrated solution and 1300g of a mixture of ethanol and water (the content of ethanol is 92 wt%) are added into a crystallizer I, a four-folding-blade open turbine and a double-layer combined paddle of a frame paddle are adopted for stirring and mixing uniformly, the temperature is raised until the solids are completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, 5 percent of dicumyl peroxide seed crystal (the average grain diameter is 600 mu m, the purity is more than or equal to 99.5 percent) of the total weight of the dicumyl peroxide crystallization material in the crystallizer I is added, the crystallization is carried out for 30min, then the temperature of the crystallizer is continuously reduced, the temperature difference between the material in the crystallizer and a cooling medium is controlled to be 3 ℃, and the temperature reduction rate is 1 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, performing solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1 to obtain dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a three-dimensional dicumyl peroxide crystal product I which is regular in shape, relatively transparent, free of obvious occlusion and coalescence and contains more small particles, and a microscopic picture is shown in figure 5, wherein the purity is 99.8%, the crystal particle size distribution is relatively uniform, and the weight of crystals with the particle size of more than or equal to 850 mu m accounts for 90% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II to be continuously cooled and crystallized, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as that of the crystallizer I, 5 percent of dicumyl peroxide seed crystal (the average particle size is 600 mu m and the purity is more than or equal to 99.5 percent) of the total weight of dicumyl peroxide crystallization materials in the crystallizer II is added to carry out crystal growth for 20min, then the crystallizer is cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 4 ℃, the cooling rate is 5 ℃/h, when the temperature is reduced to 1 ℃, solid-liquid separation is carried out on a crystal slurry II containing the dicumyl peroxide crystal II, the solid-liquid ratio in the crystallizer II is 0.6:1, and the dicumyl peroxide crystal II and the crystallization mother liquor II are obtained, the dicumyl peroxide crystal II is washed, dried and screened to obtain a dicumyl peroxide crystal product II which has a regular shape, is relatively transparent, does not obviously contain and coalesces, but contains more small three-dimensional dicumyl peroxide crystals, the microscopic photograph is similar to that in FIG. 5, the purity is 99.5%, the crystal size distribution is uniform, and the weight of the crystal with the grain size of 850 μm or more accounts for 80% of the total weight of the crystal. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 80 wt%), returning part of the mother liquor concentrated solution to the crystallizer I (the amount of the part of the mother liquor concentrated solution returned to the crystallizer I meets the requirement that the weight ratio of the condensation concentrated solution to the mother liquor concentrated solution is 2: 1; the amount of the part of the mother liquor concentrated solution returned to the crystallizer I enables the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene to be 2:1), and adding the rest of the mixture of ethanol and water (the ethanol content is 92 wt%, the ratio of the weight of the mixture of the ethanol and the water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 1:1) to the crystallization mother liquor Cooling and crystallizing in a crystallizer III, adding dicumyl peroxide crystal seeds (with average particle size of 600 microns and purity not less than 99.5%) accounting for 5% of the total weight of dicumyl peroxide crystal materials in the crystallizer III when the temperature is reduced to 0.1 ℃ above the saturation temperature by using a stirring blade same as that of the crystallizer I, crystallizing for 15min, cooling the crystallizer, controlling the temperature difference between the materials in the crystallizer and a cooling medium to be 10 ℃, the cooling rate to be 2 ℃/h, cooling to-10 ℃, carrying out solid-liquid separation on a crystal slurry III containing dicumyl peroxide crystals III, and obtaining dicumyl peroxide crystals III and a crystallization mother liquor III, wherein the solid-liquid ratio in the crystallizer III is 0.6:1, and the dicumyl peroxide crystals III are recrystallized, washed, dried and screened by using a crystallization solvent to obtain a dicumyl peroxide crystal product III with a regular shape, relatively transparent property, no obvious occlusion and coalescence, but containing more small three-dimensional dicumyl peroxide crystals, the photomicrograph is similar to that of FIG. 5, the purity is 99.3%, and the crystal size distribution is not uniform, wherein the proportion of the weight of the crystal with the particle size of more than or equal to 850 mu m in the total weight of the crystal is 75%.
[ example 5 ]
The procedure of example 1 was followed except that the temperature at which the seed crystals were added was the saturation temperature.
The obtained product I is a three-dimensional dicumyl peroxide crystal product I which is relatively regular in shape, relatively transparent, free of obvious occlusion and coalescence and relatively high in small particle size, a microscopic picture is similar to that shown in figure 5, the purity is 99.7%, the particle size distribution of the crystals is relatively uniform, and the weight of the crystals with the particle size of more than or equal to 850 mu m accounts for 85% of the total weight of the crystals.
The obtained three-dimensional dicumyl peroxide crystal product II is regular in shape, relatively transparent, free of obvious occlusion and coalescence and relatively high in small particle size, and a microscopic picture is similar to that in the picture shown in figure 5, the purity is 99.3%, the crystal size distribution is uneven, and the weight of crystals with the particle size of more than or equal to 850 mu m accounts for 78% of the total weight of the crystals.
The obtained product III is a three-dimensional dicumyl peroxide crystal product III which is regular in shape, transparent, free of occlusion and coalescence, and a microscopic picture is similar to that in the picture shown in figure 5, the purity is 99.2%, the crystal granularity distribution is uneven, wherein the weight of the crystal with the grain diameter of more than or equal to 850 mu m accounts for 73% of the total weight of the crystal.
[ example 6 ]
The procedure of example 1 was followed except that the seed addition was reduced by:
1600g of dicumyl peroxide condensed concentrated solution (the content of DCP is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 700g of mother liquor concentrated solution and 1300g of a mixture of ethanol and water (the content of ethanol is 92 wt%) are added into a crystallizer I, a four-folding-blade open turbine and a double-layer combined paddle of a frame paddle are adopted for stirring and mixing uniformly, the temperature is raised until the solids are completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) accounting for 0.4 weight percent of the total weight of the dicumyl peroxide crystalline material in the crystallizer I, growing crystals for 30min, then continuously reducing the temperature of the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 3 ℃, the temperature reduction rate to be 1 ℃/h, and after liquid in the crystallizer is layered and disappears, adjusting the temperature reduction rate to be 2 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, performing solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1 to obtain dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a three-dimensional dicumyl peroxide crystal product I which is regular in shape, relatively transparent, free of obvious occlusion and coalescence and contains more small particles, and a microscopic picture is similar to that shown in a picture in a figure 5, the purity is 99.5%, the crystal particle size distribution is uniform, and the weight of crystals with the particle size of more than or equal to 850 mu m accounts for 80% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II for continuous cooling crystallization, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as the crystallizer I, dicumyl peroxide seed crystals (the average particle size is 600 mu m and the purity is more than or equal to 99.5%) in an amount which is 0.4 percent of the total weight of dicumyl peroxide crystallization materials in the crystallizer II are added for crystallization for 20min, then the crystallizer is continuously cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 5 ℃, the cooling rate is 1.5 ℃/h, when the temperature is reduced to 5 ℃, solid-liquid separation is carried out on a crystal slurry II containing the dicumyl peroxide crystals II, the solid-liquid ratio in the crystallizer II is 0.6:1, the dicumyl peroxide crystals II and the crystallization mother liquor II are obtained, and the dicumyl peroxide crystals II are washed, dried and screened to obtain the dicumyl peroxide crystals II which have regular shapes, are relatively transparent and have no obvious occlusion and coalescence, However, the microscopic photograph of the product II containing a large amount of small particles of the three-dimensional dicumyl peroxide crystals is similar to that in FIG. 5, the purity is 99.2%, and the particle size distribution of the crystals is uniform, wherein the weight of the crystals with the particle size of not less than 850 μm accounts for 75% of the total weight of the crystals. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 80 wt%), returning part of the mother liquor concentrated solution to the crystallizer I (the amount of the part of the mother liquor concentrated solution returned to the crystallizer I meets the requirement that the weight ratio of the condensation concentrated solution to the mother liquor concentrated solution is 2: 1; the amount of the part of the mother liquor concentrated solution returned to the crystallizer I enables the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene to be 2:1), and adding the rest of the mixture of ethanol and water (the ethanol content is 92 wt%, the ratio of the weight of the mixture of the ethanol and the water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 1:1) to the crystallization mother liquor Cooling and crystallizing in a crystallizer III, cooling to 0.1 deg.c over the saturation temperature with stirring blades the same as that of the crystallizer I, adding dicumyl peroxide crystal seed in 0.4 wt% of the total dicumyl peroxide crystallizing material in the crystallizer III, maintaining the average grain size of 600 micron and purity over 99.5%, crystallizing for 15min, cooling to 5 deg.c and cooling rate of 2 deg.c/h, cooling to-10 deg.c, solid-liquid separating the slurry III containing dicumyl peroxide crystal III in the ratio of 0.6 to 1 to obtain dicumyl peroxide crystal III and crystallized mother liquid III, recrystallizing dicumyl peroxide crystal III in crystallizing solvent, washing, drying and sieving to obtain dicumyl peroxide crystal III with regular shape, high transparency, no obvious inclusion and coalescence, However, the microscopic photograph of the product III containing a large amount of small particles of the three-dimensional dicumyl peroxide crystals is similar to that in FIG. 5, the purity is 99.1%, the particle size distribution of the crystals is uniform, and the weight of the crystals with the particle size of not less than 850 μm accounts for 70% of the total weight of the crystals.
[ example 7 ] A method for producing a polycarbonate
The procedure is as in example 1, except that the crystallization solvent is absolute ethanol,
the dicumyl peroxide crystal product I is regular in shape, transparent, and free of occlusion and coalescence;
the dicumyl peroxide crystal product II is regular in shape, transparent, and free of occlusion and coalescence;
the dicumyl peroxide crystal product III is regular in shape, transparent, and has a solid shape without occlusion and coalescence.
[ example 8 ]
The procedure is as in example 1, except that the crystallization solvent is a mixture of methanol and water (methanol content 92% by weight).
The dicumyl peroxide crystal product I is regular in shape, transparent, free of occlusion and coalescence and stereoscopic;
the dicumyl peroxide crystal product II is regular in shape, transparent, free of occlusion and coalescence and in a three-dimensional shape;
the dicumyl peroxide crystal product III is regular in shape, transparent, and has a solid shape without occlusion and coalescence.
[ example 9 ] A method for producing a polycarbonate
According to example 1, except that the mother liquor concentrate is not returned to the crystallizer I, specifically:
1600g of dicumyl peroxide condensed concentrated solution (the content of DCP is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 1300g of a mixture of ethanol and water (the content of ethanol is 92 wt%) is added into a crystallizer I, a four-folding-blade open turbine and a double-layer combined blade of a frame paddle are adopted for stirring and mixing uniformly, the temperature is raised until the solid is completely dissolved, and then the temperature is reduced. When the temperature is reduced to 0.3 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5% of the total weight of the dicumyl peroxide crystalline material in the crystallizer I, growing crystals for 30min, then continuously reducing the temperature of the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 3 ℃, the temperature reduction rate to be 1 ℃/h, and after liquid in the crystallizer is layered and disappears, adjusting the temperature reduction rate to be 2 ℃/h. When the temperature of a crystallizer I reaches 20 ℃, carrying out solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I, wherein the solid-liquid ratio in the crystallizer I is 0.6:1, thus obtaining dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a sheet dicumyl peroxide crystal product I which is regular in shape, transparent, free of occlusion and coalescence, and a microscopic picture is shown in figure 3, wherein the purity is 99.91%, the crystal granularity is uniformly distributed, and the weight of crystals with the grain size of more than or equal to 850 mu m accounts for 98% of the total weight of the crystals. The crystallization mother liquor I enters a crystallizer II to be continuously cooled and crystallized, when the temperature is reduced to 0.2 ℃ above the saturation temperature by adopting a stirring blade which is the same as that of the crystallizer I, dicumyl peroxide crystal seeds (the average particle size is 600 mu m and the purity is more than or equal to 99.5%) accounting for 5 percent of the total weight of dicumyl peroxide crystallization materials in the crystallizer II are added to grow the crystals for 20min, then the crystallizer is cooled, the temperature difference between the materials in the crystallizer and a cooling medium is controlled to be 5 ℃, the cooling rate is 1.5 ℃/h, when the temperature is reduced to 5 ℃, solid-liquid separation is carried out on crystal slurry II containing the dicumyl peroxide crystals II, the solid-liquid ratio in the crystallizer II is 0.6:1, so that dicumyl peroxide crystals II and crystallization mother liquor II are obtained, and the dicumyl peroxide crystals II are washed, dried and screened to obtain a sheet dicumyl peroxide crystal product II with regular shape, transparency, no occlusion and coalescence, the microphotograph is similar to that of FIG. 3, the purity is 99.85%, the crystal size distribution is uniform, and the weight of the crystal with the particle size of 850 μm or more accounts for 95% of the total weight of the crystal. Recovering and concentrating the solvent of the crystallization mother liquor II to obtain mother liquor concentrated solution rich in dicumyl peroxide (the concentration of the dicumyl peroxide is 80 wt%), adding a mixture of all the mother liquor concentrated solution, ethanol and water (the content of the ethanol is 92 wt%, the ratio of the weight of the mixture of the ethanol and the water to the weight of the dicumyl peroxide-containing crystallization material in the crystallizer is 1:1) into a crystallizer III for cooling crystallization, adopting a stirring blade same as that of the crystallizer I, cooling to 0.1 ℃ above the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m, the purity is more than or equal to 99.5%) which are 5 wt% of the total weight of the dicumyl peroxide crystallization material in the crystallizer III, carrying out crystal growth for 15min, cooling the crystallizer, controlling the temperature difference between the material in the crystallizer and a cooling medium to be 5 ℃, and the cooling rate to be 2 ℃/h, and (3) cooling to-10 ℃, carrying out solid-liquid separation on a crystal slurry III containing dicumyl peroxide crystals III, wherein the solid-liquid ratio in the crystallizer III is 0.6:1 to obtain dicumyl peroxide crystals III and a crystallization mother liquor III, the dicumyl peroxide crystals III are recrystallized by a crystallization solvent, washed, dried and screened to obtain a flaky dicumyl peroxide crystal product III which is regular in shape, transparent, free of occlusion and coalescence, a microscopic picture is similar to that shown in a figure 3, the purity is 99.8%, the crystal granularity is uniformly distributed, and the weight of the crystals with the grain size of more than or equal to 850 mu m accounts for 93% of the total weight of the crystals.
[ example 10 ]
The process of example 1 was followed except that crystallizer I, crystallizer II and crystallizer III were all single layer paddles as shown in fig. 8.
Dicumyl peroxide crystal product I is in a three-dimensional shape with a regular shape, insufficient transparency, no significant occlusion and coalescence, but a certain amount of fine powder is present, and a photomicrograph is shown in FIG. 6;
the dicumyl peroxide crystal product II has a stereo shape which is regular in shape, not transparent enough, not obviously occluded and agglomerated, but has a certain amount of fine powder, and a photomicrograph is similar to that in FIG. 6;
dicumyl peroxide crystal product III is a solid with a regular shape, insufficient transparency, no significant occlusion and coalescence, but with a certain amount of fine powder present, and the photomicrograph is shown in FIG. 6.
[ COMPARATIVE EXAMPLE 1 ]
According to the conventional crystallization process. 1600g of dicumyl peroxide condensed concentrated solution (wherein the DCP content is 91 wt%, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 10:1), 1300g of a mixture of ethanol and water (the ethanol content is 96%) is added into a crystallizer I, an anchor type stirring paddle is adopted for uniformly mixing, the temperature is raised until the solid is completely dissolved, and then the temperature is reduced. When the temperature is reduced to the saturation temperature, adding dicumyl peroxide seed crystals (the average particle size is 600 mu m and the purity is more than or equal to 99.5 percent) accounting for 5 percent of the total weight of the dicumyl peroxide crystallization materials in the crystallizer, continuously reducing the temperature of the crystallizer, controlling the temperature difference between the materials in the crystallizer and a cooling medium to be 6 ℃, the temperature reduction rate to be 2 ℃/h, when the temperature of the crystallizer I reaches 5 ℃, carrying out solid-liquid separation on a crystal slurry I containing dicumyl peroxide crystals I to obtain dicumyl peroxide crystals I and a crystallization mother liquor I, washing, drying and screening the dicumyl peroxide crystals I to obtain a flaky dicumyl peroxide crystal product I which is irregular in shape, poor in transparency and obvious in occlusion and coalescence, wherein a microscopic picture is shown in figure 4, the purity is 99.3%, the crystal granularity distribution is uneven, and the weight of crystals with the particle size of more than or equal to 850 mu m accounts for 65% of the total weight of the crystals.
What has been described above is merely a preferred example of the present invention. It should be noted that other equivalent variations and modifications can be made by those skilled in the art based on the technical teaching provided by the present invention, and the protection scope of the present invention should be considered.
Claims (10)
1. A method for crystallizing dicumyl peroxide comprises the following steps:
a) carrying out first cooling crystallization on the condensation concentrated solution containing dicumyl peroxide and a crystallization solvent in a crystallizer I to obtain crystal slurry I containing dicumyl peroxide crystals;
b) carrying out solid-liquid separation on the crystal slurry I to obtain a dicumyl peroxide crystal I and a crystallization mother liquor I, and washing, drying and screening the dicumyl peroxide crystal I to obtain a dicumyl peroxide crystal product I;
c) carrying out second cooling crystallization on the crystallization mother liquor I in a crystallizer II to obtain crystal slurry II containing dicumyl peroxide crystals;
d) carrying out solid-liquid separation on the crystal slurry II to obtain a dicumyl peroxide crystal II and a crystallization mother liquor II, and washing, drying and screening the dicumyl peroxide crystal II to obtain a dicumyl peroxide crystal product II;
e) carrying out solvent recovery and concentration on the crystallization mother liquor II to obtain mother liquor concentrated solution, and carrying out third cooling crystallization on all or part of the mother liquor concentrated solution and the crystallization solvent in a crystallizer III to obtain crystal slurry III containing dicumyl peroxide crystals;
f) and (3) carrying out solid-liquid separation on the crystal slurry III to obtain a dicumyl peroxide crystal III and a crystallization mother liquor III, and carrying out solvent recrystallization, washing, drying and screening on all or part of the dicumyl peroxide crystal III to obtain a dicumyl peroxide crystal product III.
2. The crystallization method according to claim 1, further comprising adding a crystal habit modifier to the crystallizer I;
preferably, the crystal habit modifier is selected from at least one of 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene, 1, 3-trimethyl-3-phenylindane, 2,4, 6-triphenyl-4, 6-dimethyl-1-heptene, a polymer of alpha-methylstyrene and a polymer of alpha-methylstyrene;
preferably, the addition amount of the crystal habit modifier is 0.01-5% of the weight of the condensation concentrate.
3. The crystallization process according to claim 1 or 2, characterized in that it further comprises in step e) concentrating part of the mother liquor back into the crystallizer I;
preferably, the amount of part of the mother liquor concentrated and returned to the crystallizer I is 1-10: 1, more preferably 1-3: 1, of the weight ratio of the condensed concentrated liquor to the mother liquor concentrated liquor;
more preferably, part of the mother liquor is concentrated and returned to the crystallizer I in an amount such that the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 0.1 to 5: 1.
4. The crystallization method according to any one of claims 1 to 3, characterized in that the crystallization method further comprises returning part of the dicumyl peroxide crystals III to the crystallizer I in step f);
preferably, the amount of part of the dicumyl peroxide crystals III returned to the crystallizer I is 5-20: 1 of the weight ratio of the condensation concentrated solution to the dicumyl peroxide crystals III;
preferably, part of the dicumyl peroxide crystals III is returned to the crystallizer I in such an amount that the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 0.1 to 5: 1.
5. The crystallization method according to any one of claims 1 to 4, characterized in that the crystallization method further comprises: seed crystals are independently added in the processes of the first cooling crystallization, the second cooling crystallization and the third cooling crystallization;
preferably, the seed crystal is dicumyl peroxide crystal, more preferably, the particle size of the seed crystal is 425-710 μm, and more preferably, the purity of the seed crystal is more than or equal to 99.5%;
preferably, the addition amount of the seed crystals is 0.5-10% of the total weight of dicumyl peroxide crystallization materials in the crystallizer before seed crystal addition;
more preferably, the seed crystal is added at the temperature of 0.1-0.5 ℃ above the crystallization saturation temperature;
more preferably, the temperature is kept constant after the seed crystal is added, and then a slow cooling mode is adopted for the crystallizer; more preferably, the cooling rate is 0.1-3 ℃/h before the liquid-liquid two-phase layering disappears, and the cooling rate is 1-10 ℃/h after the liquid-liquid two-phase layering disappears;
more preferably, the temperature difference between the material in the crystallizer and the cooling medium is controlled to be less than or equal to 10 ℃ and more preferably less than or equal to 5 ℃ during the crystallization process of the crystallizer.
6. The crystallization method according to any one of claims 1 to 5, wherein the concentration of dicumyl peroxide in the condensation concentrate containing dicumyl peroxide is 80 to 95 wt%;
preferably, in the condensed and concentrated solution containing dicumyl peroxide, the ratio of the total concentration of cumene hydroperoxide, alpha-methylstyrene and cumene to the total concentration of 2, 4-diphenyl-4-methyl-1-pentene and 2, 4-diphenyl-4-methyl-2-pentene is 5-20: 1.
7. The crystallization method according to any one of claims 1 to 6, wherein the concentration of dicumyl peroxide in the mother liquor concentrate is 70 to 85 wt%;
preferably, the purity of the dicumyl peroxide crystal III is 85-99%.
8. The crystallization method according to any one of claims 1 to 7, characterized in that the crystallization solvent is ethanol or methanol;
preferably, the crystallization solvent is a mixture of ethanol and water with a water content of 5-15 wt% or a mixture of methanol and water with a water content of 5-10 wt%;
more preferably, the weight ratio of the mixture of ethanol and water to the weight of the dicumyl peroxide-containing crystalline material in the crystallizer is 0.5-1: 1;
more preferably, the ratio of the weight of the mixture of methanol and water to the weight of the dicumyl peroxide-containing crystalline material in the crystallizer is 0.6 to 1.2: 1.
9. The crystallization method according to any one of claims 1 to 8, wherein the stirring blades of the crystallizer I, the crystallizer II and the crystallizer III are each independently of the other a double-layer combination, more preferably a combination of a four-blade open turbine and a frame paddle; and/or the presence of a gas in the gas,
the solid-liquid ratio in the crystallizer I, the crystallizer II and the crystallizer III is 0.4-0.8: 1 respectively and independently; and/or the presence of a gas in the gas,
the temperature of the first cooling crystallization is 15-20 ℃; and/or the temperature of the second cooling crystallization is-5 ℃ to 5 ℃; and/or the temperature of the third cooling crystallization is-10 ℃ to 5 ℃.
10. Dicumyl peroxide prepared by the crystallization process according to any one of claims 1 to 9;
preferably, the dicumyl peroxide is in a flake or solid shape;
preferably, the purity of the dicumyl peroxide is more than or equal to 99.8 percent;
preferably, the dicumyl peroxide has a uniform crystal size distribution;
preferably, in the dicumyl peroxide, the weight ratio of the crystals with the particle size of more than or equal to 850 mu m to the total weight of the crystals is more than or equal to 95 percent.
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