CN116059680A - Fin type device and method for purifying p-phenylenediamine through melt crystallization - Google Patents
Fin type device and method for purifying p-phenylenediamine through melt crystallization Download PDFInfo
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Abstract
The invention provides a method and a device for purifying p-phenylenediamine. The invention takes p-phenylenediamine as a main component, and impurities comprise raw materials of mixed diamine such as m-phenylenediamine, o-phenylenediamine and the like, and the high-purity p-phenylenediamine is separated by adopting a melting crystallization method through a self-made crystallizer. The p-phenylenediamine purification method with specific steps provided by the invention combines corresponding purification devices, so that a p-phenylenediamine product with the purity of 99.99% can be obtained.
Description
Technical Field
The invention belongs to the technical field of p-phenylenediamine purification, relates to a p-phenylenediamine purification method and a p-phenylenediamine purification device, and particularly relates to fin type melting crystallization p-phenylenediamine purification equipment and a p-phenylenediamine purification method.
Background
p-Phenylenediamine (p-phenyl), also known as Wu Ersi D,the chemical formula is C 6 H 8 N 2 Is one of the simplest aromatic diamine, is also an intermediate with wide application, is widely used for preparing azo dyes and high molecular polymers, can also be used for producing fur dyes, rubber anti-aging agents and photographic developers, and is also a common sensitive reagent for detecting iron and copper. As the use of p-phenylenediamine becomes increasingly widespread as a basic chemical agent, the purity requirements for p-phenylenediamine are increasing in the industry. At present, a water/xylene binary solvent is used for extracting crude p-phenylenediamine, impurities are dissolved in xylene, the p-phenylenediamine is dissolved in water, and a pure product is obtained by evaporating an aqueous solution, but the solution crystallization method has the environmental problems of long flow, more main equipment, high investment, high energy consumption in the investment process and the like. As disclosed in jp2011026224 by asohidemitsu et al, crude colored p-phenylenediamine is purified by distillation under reduced pressure in the presence of a reducing mineral to yield white high purity p-phenylenediamine; as described in RU20100152659 by aefievich et al, the crude p-phenylenediamine product containing 90-98 mass percent of p-phenylenediamine and 2-10 percent of tar residue is heated to 100-260 ℃ under inert gas flow, and purified by sublimation crystallization to obtain a p-phenylenediamine product with the purity of 99.5-99.9 percent. There are some corresponding reports in China, for example, CN100358860 describes a method for refining p-phenylenediamine by crystallization of solution, the p-phenylenediamine is dissolved in water, cooled and crystallized to form granular crystals, and then the granular crystals are separated and dried in vacuum to form p-phenylenediamine finished products, the white product rate is up to 100%, but the purity and the yield are not reported; also described in CN101250113 is a process for refining p-phenylenediamine in combination with a rectifying and melt-crystalline phase. By controlling the operation parameters, the p-phenylenediamine product with the purity of 99.99 percent can be obtained, but the method has the defects of high energy consumption, complex process, difficult operation, long production period and the like; in addition, cao Xuezeng et al, prepared crude p-phenylenediamine from nitroaniline, firstly distilled under reduced pressure to remove water, then heated continuously to sublimate the p-phenylenediamine under reduced pressure, wherein the vacuum degree is 0.05-0.07 mpa, the oil bath temperature is 230-240 ℃, the gas phase temperature is 55-65 ℃, and white p-phenylenediamine crystals are obtained by sublimation; CN109232276a provides a region using microwave means, generalThe p-phenylenediamine crude product is locally smelted and purified at least once in a heating mode of molecular vibration, and impurities are enriched, and the method is only suitable for refining the p-phenylenediamine crude product with the concentration of 99.5%; ding Junwei heating and melting p-phenylenediamine in crystallizer, cooling and crystallizing after stabilizing for a period of time, discharging mother liquor for a preset time, gradually raising temperature for sweating operation, naturally discharging after the heated crystal layer is completely melted, and collecting the product. The crude product of 92 percent of p-phenylenediamine is used as raw material for purification, and the purity of the p-phenylenediamine is more than 99.5 percent.
However, the relative content of p-phenylenediamine to be purified is relatively high in the above methods, and the p-phenylenediamine is relatively low, so that the above methods are not applicable and the ideal effect is not achieved; meanwhile, in the above methods, the purification temperature is high, the process is generally complex, and the technology, the energy consumption, the greenization and other aspects need to be improved, so whether industrialization can be realized or not is yet to be verified.
Therefore, how to find a more suitable p-phenylenediamine purification method, solve the defects of the existing p-phenylenediamine purification method, be more beneficial to industrial application, meet the various requirements of industrial application, and become one of the problems to be solved urgently for research and development enterprises and first-line researchers in the industry.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method and a device for purifying p-phenylenediamine, in particular to a method for purifying p-phenylenediamine by fin type melt crystallization. According to the invention, the operation parameters of the purification process are optimized by adopting a melt crystallization purification mode, and meanwhile, the melt crystallization equipment is independently designed according to the obtained optimal operation parameters, so that the product separation rate is improved, the polymer grade p-phenylenediamine product is obtained, the market supply is stable, and meanwhile, the preparation method is simple, strong in controllability, strong in repeatability, environment-friendly and environment-friendly, and is more suitable for industrial production and practical application.
The invention provides a method for purifying p-phenylenediamine, which comprises the following steps:
1) Feeding the liquid p-phenylenediamine raw material into a melting crystallizer, heating and melting, cooling, keeping balance, and removing dead materials in a dead material zone to obtain coarse p-phenylenediamine crystals in the melting crystallizer;
2) Opening a discharge hole at the bottom of the melting crystallizer, heating the p-phenylenediamine crude crystals obtained in the steps to the sweating temperature again, keeping balance, and discharging sweat to obtain p-phenylenediamine crystals;
3) Continuously heating the p-phenylenediamine crystals obtained in the steps to a temperature above the freezing point of the p-phenylenediamine raw material, and discharging impurities from the bottom to obtain the p-phenylenediamine crystals after impurity removal;
4) Continuously heating the p-phenylenediamine crystals obtained in the steps until the p-phenylenediamine crystals reach the vicinity of the solidifying point of the pure p-phenylenediamine, and further discharging impurities to obtain the p-phenylenediamine crystals after further impurity removal;
5) Heating the p-phenylenediamine crystals obtained in the step after further impurity removal again to obtain a liquid product;
6) Repeating the steps 1) to 4) by using the liquid product obtained in the steps to obtain the multi-stage purified p-phenylenediamine.
Preferably, the temperature of the heating and melting is 135-150 ℃;
the cooling rate is 6-8 ℃/h;
in the step 1), the temperature for keeping balance is 35-45 ℃;
in the step 1), the time for maintaining balance is 3-4 hours;
in the process of the step 1), a discharge hole at the bottom of the melting crystallizer is in a closed state.
Preferably, the purity of the liquid p-phenylenediamine raw material is 89% -95%;
the liquid p-phenylenediamine raw material comprises m-phenylenediamine and/or o-phenylenediamine impurities;
the heating rate of the reheating is 3-8 ℃/h;
the sweating temperature is 130-135 ℃;
the time for maintaining balance is 60-120 min.
Preferably, the heating rate of the continuous heating is 3-4 ℃;
the solidifying point of the p-phenylenediamine raw material is 135-138 ℃;
the temperature above the solidifying point of the p-phenylenediamine raw material is specifically 5-10 ℃ above the solidifying point of the p-phenylenediamine raw material;
in the step 3), the impurity discharge is specifically to remove low-component impurities;
the p-phenylenediamine crystals after impurity removal comprise higher-component p-phenylenediamine crystals.
Preferably, the heating rate of the continuous heating is 2.5-4.5 ℃/h;
the solidifying point of the pure p-phenylenediamine is 139-141 ℃;
the vicinity of the solidifying point of the pure p-phenylenediamine is specifically the solidifying point of the pure p-phenylenediamine which is (+/-) (5-10) DEG C;
in the step 4), the impurities are further discharged, in particular the low-component impurities are further discharged;
the p-phenylenediamine crystals after further impurity removal comprise higher-component p-phenylenediamine crystals;
the multi-stage purified p-phenylenediamine is polymer grade p-phenylenediamine.
Preferably, the temperature rising rate of the secondary temperature rising is 1.5-2.5 ℃/h;
the reheating is specifically to heat up again until the materials are completely melted;
the temperature of the secondary heating is 145-160 ℃;
the number of repetition is 2-6;
the purity of the p-phenylenediamine after the multistage purification is 99.990-99.995 percent.
The invention provides a p-phenylenediamine purification device, which comprises a melting crystallizer;
the melting crystallizer is specifically a vertical melting crystallizer with upper inlet and lower outlet;
the melt crystallizer comprises a purification zone and a dead zone from top to bottom.
Preferably, the melt crystallizer is a neck melt crystallizer;
the melt crystallizer comprises a fin melt crystallizer;
the volume ratio of the purification zone to the dead zone is (18-20): 1.
preferably, the dead material area is provided with a spiral sieve plate;
the purification zone is provided with a plurality of groups of fin structures in the transverse direction;
the number of the fins of the fin structure is 3-5;
different fins in a group of fins are sequentially adjacent to each other along the height direction of the purification zone.
Preferably, the distance between adjacent fins in the group of fins is 0.5-1.5 cm;
the transverse dimension of the fin is 1/3-2/3 of the inner diameter of the purification zone tube;
the melt crystallizer is also provided with an outer jacket for heating.
The invention provides a method for purifying p-phenylenediamine, which comprises the following steps that firstly, a liquid p-phenylenediamine raw material is sent into a melting crystallizer, and after heating and melting, cooling is carried out, balance is kept, and dead materials in a dead material area are removed, so that p-phenylenediamine coarse crystals in the melting crystallizer are obtained; then opening a discharge hole at the bottom of the melting crystallizer, heating the crude p-phenylenediamine crystals obtained in the steps to the sweating temperature again, keeping balance, and discharging sweat to obtain p-phenylenediamine crystals; then continuously heating the p-phenylenediamine crystals obtained in the steps to a temperature above the freezing point of the p-phenylenediamine raw material, and discharging impurities from the bottom to obtain the p-phenylenediamine crystals after impurity removal; then continuously heating the p-phenylenediamine crystals obtained in the steps until the p-phenylenediamine crystals reach the vicinity of the solidifying point of the pure p-phenylenediamine, and further discharging impurities to obtain the p-phenylenediamine crystals after further impurity removal; continuously heating the p-phenylenediamine crystals obtained in the steps after further impurity removal again to obtain a liquid product; and finally, repeating the steps 1) to 4) by using the liquid product obtained in the steps to obtain the multi-stage purified p-phenylenediamine. Compared with the prior art, the method is relatively high in the relative content of the p-phenylenediamine to be purified in the existing p-phenylenediamine purification method, and is not applicable to the situation that the relative content of the p-phenylenediamine is low, so that the ideal effect is not achieved; and the purification temperature is high, the process is generally complex, whether industrialization can be realized or not is yet to be verified, and the problems of technology, energy consumption, greenization and the like need to be improved. The invention mainly aims to solve the technical problem of purifying low-purity crude p-phenylenediamine to high-purity p-phenylenediamine, solves the problems of immature purification technology, high energy consumption, environmental protection, high operation difficulty and the like in the prior art, and particularly designs a p-phenylenediamine purification method with specific steps, and combines corresponding purification devices, so that a p-phenylenediamine product with the purity of 99.99 percent can be obtained, and the p-phenylenediamine has the advantages of no solvation, environmental protection, low energy consumption, high product purity and the like.
The fin type melting crystallization device and the purification method provided by the invention take the p-phenylenediamine as a main component, impurities comprise raw materials of mixed diamine such as m-phenylenediamine, o-phenylenediamine and the like, the high-purity p-phenylenediamine is separated by adopting a self-made crystallizer through a melting crystallization method, the melting crystallization device has the advantages of no solvation, environmental friendliness, low energy consumption, high product purity and the like, and a fin structure is arranged in the fin type melting crystallizer, so that the fin type melting crystallization device has the functions of increasing the heat transfer area, reducing the metastable area of crystallization, controlling the nucleation process and preventing the system from violently nucleating to occlude more impurities under higher supercooling degree; meanwhile, a spiral sieve plate structure is arranged in the crystallizer, so that a crystal layer of the purification area can be supported, and the loss of products caused by falling of the crystal layer in the sweating process is prevented. Compared with the existing methods (solvent crystallization method and sublimation desublimation crystallization method), the method has the advantages of no solvation, environmental friendliness, low energy consumption, high product purity and the like.
Experimental results show that the device and the method for purifying the p-phenylenediamine by necking melting crystallization have the advantages of no solvation, simple operation, environmental friendliness, low energy consumption, high product purity and the like, and can finally obtain the p-phenylenediamine with the purity of more than 99.99 percent.
Drawings
Fig. 1 is a schematic diagram of the structure of a fin type melt crystallizer provided by the invention.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The source of the p-phenylenediamine used in the present invention is not particularly limited and may be commercially available or prepared according to conventional methods well known to those skilled in the art.
All noun expressions and abbreviations of the invention belong to the conventional noun expressions and abbreviations in the field of the art, and each noun expression and abbreviation is clear and definite in the relevant application field, and the person skilled in the art can understand clearly, accurately and uniquely according to the noun expressions and abbreviations.
The invention provides a method for purifying p-phenylenediamine, which comprises the following steps:
1) Feeding the liquid p-phenylenediamine raw material into a melting crystallizer, heating and melting, cooling, keeping balance, and removing dead materials in a dead material zone to obtain coarse p-phenylenediamine crystals in the melting crystallizer;
2) Opening a discharge hole at the bottom of the melting crystallizer, heating the p-phenylenediamine crude crystals obtained in the steps to the sweating temperature again, keeping balance, and discharging sweat to obtain p-phenylenediamine crystals;
3) Continuously heating the p-phenylenediamine crystals obtained in the steps to a temperature above the freezing point of the p-phenylenediamine raw material, and discharging impurities from the bottom to obtain the p-phenylenediamine crystals after impurity removal;
4) Continuously heating the p-phenylenediamine crystals obtained in the steps until the p-phenylenediamine crystals reach the vicinity of the solidifying point of the pure p-phenylenediamine, and further discharging impurities to obtain the p-phenylenediamine crystals after further impurity removal;
5) Heating the p-phenylenediamine crystals obtained in the step after further impurity removal again to obtain a liquid product;
6) Repeating the steps 1) to 4) by using the liquid product obtained in the steps to obtain the multi-stage purified p-phenylenediamine.
Firstly, feeding a liquid p-phenylenediamine raw material into a melting crystallizer, cooling after heating and melting, keeping balance, and removing dead materials in a dead material area to obtain coarse p-phenylenediamine crystals in the melting crystallizer.
In the present invention, the temperature of the heating and melting is preferably 135 to 150 ℃, more preferably 138 to 147 ℃, and still more preferably 141 to 143 ℃.
In the present invention, the cooling rate is preferably 6 to 8℃per hour, more preferably 6.4 to 7.6℃per hour, and still more preferably 6.8 to 7.2℃per hour.
In the present invention, the temperature at which the equilibrium is maintained in the step 1) is preferably 35 to 45 ℃, more preferably 37 to 43 ℃, and still more preferably 39 to 41 ℃.
In the present invention, the time for maintaining the equilibrium in the step 1) is preferably 3 to 4 hours, more preferably 3.2 to 3.8 hours, and still more preferably 3.4 to 3.6 hours.
In the process of the step 1), the discharge port at the bottom of the melting crystallizer is preferably closed.
In the present invention, the purity of the liquid p-phenylenediamine raw material is preferably 89% to 95%, more preferably 90% to 94%, and still more preferably 91% to 92%.
In the present invention, the liquid paraphenylenediamine raw material preferably includes m-phenylenediamine and/or o-phenylenediamine impurities, more preferably m-phenylenediamine or o-phenylenediamine impurities.
The invention opens the discharge hole at the bottom of the melting crystallizer, heats the crude p-phenylenediamine crystals obtained in the steps to the sweating temperature again, keeps balance, discharges sweat, and obtains p-phenylenediamine crystals.
In the present invention, the reheating rate is preferably 3 to 8 ℃/h, more preferably 4 to 7 ℃/h, and still more preferably 5 to 6 ℃/h.
In the present invention, the sweating temperature is preferably 130 to 135 ℃, more preferably 131 to 134 ℃, and still more preferably 132 to 133 ℃.
In the present invention, the time for maintaining the balance is preferably 60 to 120 minutes, more preferably 70 to 110 minutes, and still more preferably 80 to 100 minutes.
The p-phenylenediamine crystals obtained in the steps are continuously heated to be above the solidifying point of the p-phenylenediamine raw material, impurities are discharged from the bottom, and the p-phenylenediamine crystals after impurity removal are obtained.
In the present invention, the heating rate of the continuous heating is preferably 3 to 4 ℃, more preferably 3.2 to 3.8 ℃, and still more preferably 3.4 to 3.6 ℃.
In the present invention, the solidification point of the p-phenylenediamine raw material is preferably 135 to 138 ℃, more preferably 135.5 to 137.5 ℃, and still more preferably 136 to 137 ℃.
In the present invention, the above-mentioned p-phenylenediamine raw material preferably has a solidification point of 5 to 10℃above the solidification point of the p-phenylenediamine raw material, more preferably 6 to 9℃and still more preferably 7 to 8 ℃.
In the present invention, in the step 3), the removal of impurities is particularly preferably the removal of low-component impurities.
In the present invention, the purified p-phenylenediamine crystals preferably comprise higher component p-phenylenediamine crystals.
The p-phenylenediamine crystals obtained in the steps are continuously heated to the vicinity of the solidifying point of the pure p-phenylenediamine, and impurities are further discharged, so that the p-phenylenediamine crystals obtained after further impurity removal are obtained.
In the present invention, the heating rate at which the temperature is continuously raised is preferably 2.5 to 4.5 ℃/h, more preferably 2.9 to 4.1 ℃/h, and still more preferably 3.3 to 3.7 ℃/h.
In the present invention, the solidifying point of the pure p-phenylenediamine is preferably 139 to 141 ℃, more preferably 139.4 to 140.6 ℃, and still more preferably 139.8 to 140.2 ℃.
In the present invention, the vicinity of the solidification point of the pure p-phenylenediamine is preferably a solidification point of the pure p-phenylenediamine of + -5-10 deg.c, more preferably + -6-9 deg.c, and still more preferably + -7-8 deg.c.
In the present invention, in the step 4), the further removal of impurities is particularly preferably further removal of low-component impurities.
In the present invention, the further purified p-phenylenediamine crystals preferably comprise higher component p-phenylenediamine crystals.
The p-phenylenediamine crystals obtained in the steps after further impurity removal are heated again to obtain a liquid product.
In the present invention, the temperature increase rate of the reheating is preferably 1.5 to 2.5 ℃/h, more preferably 1.7 to 2.3 ℃/h, and still more preferably 1.9 to 2.1 ℃/h.
In the present invention, the reheating is preferably a reheating to complete melting.
In the present invention, the temperature of the reheating is preferably 145 to 160 ℃, more preferably 148 to 157 ℃, and still more preferably 151 to 154 ℃.
In the present invention, the temperature of step 5) is preferably higher than the temperature of step 4), the temperature of step 4) is preferably higher than the temperature of step 3), and the temperature of step 3) is preferably higher than the temperature of step 2).
And finally, repeating the steps 1) to 4) by using the liquid product obtained in the steps to obtain the multi-stage purified p-phenylenediamine.
In the present invention, the number of repetitions is preferably 2 to 6, more preferably 3 to 5.
In the present invention, the multi-stage purified p-phenylenediamine is preferably a polymer grade p-phenylenediamine having a purity (GC purity) of preferably 99.990 to 99.995%, more preferably 99.991 to 99.994%, and still more preferably 99.992 to 99.993%. The p-phenylenediamine purified by the method can reach the chromatographic purity level.
The invention relates to a complete and refined integral purification scheme, which better ensures the stability and controllability of a purification method and further improves the purity of the purified p-phenylenediamine, and the method for purifying the p-phenylenediamine by fin type melt crystallization specifically comprises the following steps:
a method for purifying p-phenylenediamine by fin type melt crystallization, comprising:
(1) Adding liquid p-phenylenediamine raw materials into a fin type melt crystallizer, and controlling the temperature of a purification zone (a melting zone) to keep the temperature of a system between 135 and 150 ℃;
(2) Controlling the temperature of a purification zone, cooling the p-phenylenediamine raw material in the step (1) to room temperature at a constant cooling rate, keeping the temperature of a melting zone between 35 and 45 ℃ in the process, and subtracting dead materials after balancing for 3 to 4 hours to obtain p-phenylenediamine coarse crystals;
(3) Controlling the temperature of a purification zone, heating the p-phenylenediamine crude crystals obtained in the step (2) to a sweating temperature at a constant heating rate, keeping the temperature of a melting zone at 130-135 ℃ in the process, and discharging sweat after balancing for 60-120 min to obtain p-phenylenediamine crystals; (bottom open)
(4) Sweating: and (3) heating the p-phenylenediamine crystal product obtained in the step (3) to a temperature of 5-10 ℃ above the solidifying point (mixture) at a constant heating rate, and removing low components to obtain p-phenylenediamine crystals with higher components. (bottom open)
(5) And (3) continuously heating the p-phenylenediamine crystals obtained in the step (4) to 5-10 ℃ near the solidifying point of the pure raw material (pure p-phenylenediamine) at a constant heating rate, and further removing low components to obtain p-phenylenediamine crystals with higher components. (bottom open)
(6) And (3) rapidly heating the p-phenylenediamine crystals obtained in the step (5) to 145-160 ℃, and carrying out the steps (2), (3), (4) and (5) again by taking the obtained liquid product as a raw material to obtain a second-grade p-phenylenediamine product, and the like until the purity of the obtained p-phenylenediamine product meets the requirement.
Specifically, the temperature of the step (5) is higher than that of the step (4), and the temperature of the step (4) is higher than that of the step (3).
Specifically, in the step (2), the cooling rate is constant to the crystallization temperature, the cooling rate is in the range of 6-8 ℃/h, and the crystallization temperature is in the range of 35-45 ℃.
Specifically, the body in the step (3) is heated to a sweating temperature at a constant heating rate, the heating rate ranges from 3 to 8 ℃/h, the crystallization temperature ranges from 4 to 6 ℃/h, and the crystallization temperature ranges from 130 to 135 ℃.
Specifically, the heating rate in the step (4) is 3-4 ℃, and the sweating temperature is 5-10 ℃ above the freezing point.
Specifically, the temperature of the step (5) is 145-160 ℃ when the step is heated to be completely melted, and the time is 20-30 min.
Specifically, the number of repetitions in step (6) is 2-6.
The invention controls the temperature of the purification zone of the fin type melt crystallizer respectively. The purification process of the p-phenylenediamine is mainly carried out in a purification area, and comprises the following main steps of: cooling crystallization, heating sweating and melting extraction. In order to obtain the high-purity polymer-grade p-phenylenediamine product, the melt crystallization process also needs to carry out multistage operation, namely, the high-component product of the previous stage is taken as the raw material of the next stage to be put into separation and purification. The invention comprehensively considers the purity and yield of p-phenylenediamine products through parameters such as operation temperature control, temperature rise and temperature reduction control frequency and the like, crystallization temperature, sweating temperature and temperature rise and temperature reduction rate, and provides a set of process conditions with high production efficiency.
The invention also provides a device for purifying the p-phenylenediamine, which comprises a melting crystallizer;
the melting crystallizer is specifically a vertical melting crystallizer with upper inlet and lower outlet;
the melt crystallizer comprises a purification zone and a dead zone from top to bottom.
The purification device in the invention is a purification device for the purification method of p-phenylenediamine in any of the above technical schemes, wherein the main body of the melt crystallizer consists of a purification zone and a dead zone, and does not comprise a separate melting zone.
In the present invention, the melt crystallizer is preferably a neck type melt crystallizer.
In the present invention, the melt crystallizer preferably comprises a fin melt crystallizer.
In the present invention, the volume ratio of the purification zone to the dead zone is preferably (18 to 20): 1, more preferably (18.3 to 19.7): 1, more preferably (18.5 to 19.5): 1.
in the present invention, the dead zone is preferably provided with a spiral screen deck.
In the present invention, the purification zone is preferably provided with a plurality of sets of fin structures in the transverse direction.
In the present invention, the number of fins in a group of fin structures is preferably 3 to 5.
In the present invention, the different fins in a group of fins are preferably arranged adjacently in order along the height direction of the purification zone.
In the present invention, the distance between adjacent fins in the group of fins is preferably 0.5 to 1.5cm, more preferably 0.7 to 1.3cm, and still more preferably 0.9 to 1.1cm.
In the present invention, the lateral dimension of the fins is preferably 1/3 to 2/3, more preferably 4/9 to 5/9 of the inner diameter of the purification zone tube.
In the present invention, the melt crystallizer is also preferably provided with an outer jacket for heating.
The invention relates to a complete and refined integral purification scheme, which better ensures the stability and controllability of a purification method and further improves the purity of purified p-phenylenediamine, and the fin type melting crystallization purification device specifically comprises the following structures:
the invention provides a zoned melt crystallizer, a schematic diagram of which is shown in fig. 1.
Referring to fig. 1, fig. 1 is a schematic diagram of the structure of a fin type melt crystallizer provided by the invention.
The melting crystallizer is specifically a vertical melting crystallizer with upper inlet and lower outlet;
the melting crystallizer comprises a purification zone and a dead zone from top to bottom;
the upper part is a feed inlet, and the lower part is a discharge outlet.
Specifically, the volume ratio V1:V2 of the purification zone and the dead zone in the fin type melt crystallizer can be 18:1-20:1, and can be 95:5.
Specifically, fin structures are uniformly distributed on the inner wall of the purification zone.
Specifically, the number of fins in the cross section is 3.
Specifically, the distance between the sections of different fins is 1/15 of the height of the purification zone.
Specifically, the length of the fin is 1/3-2/3 of the inner diameter of the tube.
Specifically, a spiral sieve plate is arranged at the interface of the purification zone and the dead material zone.
The invention adopts a fin crystallizer with a specific internal structure and a specific volume ratio of a purification zone to a dead zone to carry out the melting crystallization operation in the fin type melting crystallizer, wherein the p-phenylenediamine in the purification zone is subjected to a conventional melting crystallization process, and the p-phenylenediamine in the dead zone is always kept in a molten state after the dead material is subtracted. The purpose of design in this way is in order to let the molten zone provide the space in order to store sweat that produces in the sweating process after discharging mother liquor for realize physical separation between sweat and the crystal, avoid impurity in the sweat to get back to the brilliant layer again, thereby improve holistic purification effect.
The fin type melting crystallizer is internally provided with the fin structure, and has the effects of increasing the heat transfer area, reducing the metastable area of crystallization, controlling the nucleation process and preventing the system from violently nucleating to occlude more impurities under higher supercooling degree; the crystallizer is also internally provided with a spiral sieve plate structure, and the function of the spiral sieve plate structure is to support a crystal layer of the purification zone and prevent the crystal layer from falling off in the sweating process so as to cause product loss.
The invention controls the temperature of the purification zone of the fin type melt crystallizer respectively. The purification process of the p-phenylenediamine is mainly carried out in a purification area, and comprises the following main steps of: cooling crystallization, heating sweating and melting extraction. In order to obtain the high-purity polymer-grade p-phenylenediamine product, the melt crystallization process also needs to carry out multistage operation, namely, the high-component product of the previous stage is taken as the raw material of the next stage to be put into separation and purification. The device and the method for purifying the p-phenylenediamine by necking melt crystallization have the advantages of no solvation, environmental friendliness, low energy consumption and high product purity, and can finally obtain the p-phenylenediamine product with the purity of 99.99 percent.
The invention provides a fin type device and a purification method for purifying p-phenylenediamine by melt crystallization. The invention aims to solve the technical problem of purifying low-purity crude p-phenylenediamine to high-purity p-phenylenediamine, and solves the problems of immature purification technology, high energy consumption, unfavorable environmental protection, high operation difficulty and the like at the same time, and particularly designs a p-phenylenediamine purification method with specific steps, which is combined with a corresponding purification device, so that a p-phenylenediamine product with the purity of 99.99 percent can be obtained, and the p-phenylenediamine has the advantages of no solvation, environmental protection, low energy consumption, high product purity and the like.
The fin type melting crystallization device and the purification method provided by the invention take the p-phenylenediamine as a main component, impurities comprise raw materials of mixed diamine such as m-phenylenediamine, o-phenylenediamine and the like, the high-purity p-phenylenediamine is separated by adopting a self-made crystallizer through a melting crystallization method, the melting crystallization device has the advantages of no solvation, environmental friendliness, low energy consumption, high product purity and the like, and a fin structure is arranged in the fin type melting crystallizer, so that the fin type melting crystallization device has the functions of increasing the heat transfer area, reducing the metastable area of crystallization, controlling the nucleation process and preventing the system from violently nucleating to occlude more impurities under higher supercooling degree; meanwhile, a spiral sieve plate structure is arranged in the crystallizer, so that a crystal layer of the purification area can be supported, and the loss of products caused by falling of the crystal layer in the sweating process is prevented. Compared with the existing methods (solvent crystallization method and sublimation desublimation crystallization method), the method has the advantages of no solvation, environmental friendliness, low energy consumption, high product purity and the like.
Experimental results show that the device and the method for purifying the p-phenylenediamine by necking melting crystallization have the advantages of no solvation, simple operation, environmental friendliness, low energy consumption, high product purity and the like, and can finally obtain the p-phenylenediamine with the purity of more than 99.99 percent.
For further explanation of the present invention, the following describes a method and apparatus for purifying p-phenylenediamine in detail with reference to examples, but it should be understood that these examples are carried out based on the technical scheme of the present invention, and detailed embodiments and specific operation procedures are given, only for further explanation of the features and advantages of the present invention, and not limitation of the claims of the present invention, and the scope of protection of the present invention is not limited to the examples described below.
The source of the raw materials in the following examples is not particularly limited, and may be prepared by a preparation method well known to those skilled in the art or commercially available.
Example 1
An apparatus and method for purifying p-phenylenediamine by fin melt crystallization, the apparatus is shown in FIG. 1.
The method comprises the following steps:
the feed composition is shown in table 1.
Table 1 shows the crude p-phenylenediamine crude material composition in example 1 of the present invention.
TABLE 1
| Sub-items | Para-phenylenediamine | M-phenylenediamine | O-phenylenediamine | Totalizing |
| Scheme for the production of a semiconductor device | 89.90 | 5.10 | 5.00 | 100.0 |
(1) Adding liquid p-phenylenediamine raw materials into a fin type melt crystallizer, and controlling the temperature of a purification area and a melting area to keep the temperature of a system at 135-150 ℃;
(2) Controlling the temperature of a purification zone, and cooling the p-phenylenediamine raw material in the step (1) to room temperature at a constant cooling rate, wherein the temperature of a melting zone is kept at 35 ℃ in the process, and dead materials are deducted after balancing for 4 hours to obtain p-phenylenediamine crude crystals;
(3) Controlling the temperature of a purification zone, heating the crude p-phenylenediamine crystals obtained in the step (2) to a sweating temperature at a constant heating rate of 6 ℃/h, keeping the temperature of a melting zone at 135 ℃ in the process, and discharging sweat, namely fraction 1 after balancing for 1h to obtain p-phenylenediamine crystals;
(4) Sweating: heating the p-phenylenediamine crystal product obtained in the step (3) to 137 ℃ above the solidifying point (135 ℃) at a constant heating rate of 4 ℃ to remove the low component, namely fraction 2, so as to obtain p-phenylenediamine crystals with higher components.
(5) Continuously heating the p-phenylenediamine crystals obtained in the step (4) to 139 ℃ at a constant heating rate, and further removing low components to obtain p-phenylenediamine crystals with higher components
(6) And (3) heating the p-phenylenediamine crystals obtained in the step (5) to 160 ℃ to obtain a liquid product, and carrying out the steps (2), (3), (4) and (5) again as raw materials to obtain a second-grade p-phenylenediamine product, and the like, and separating the second-grade p-phenylenediamine product by 6 times until the obtained p-phenylenediamine product meets the purity requirement.
The purity and yield of each stage of p-phenylenediamine liquid product are shown in Table 2.
Table 2 shows the purity and yield of each stage of para-phenylenediamine in example 1 of the present invention in the liquid state.
TABLE 2
Note that: impurity removal = 1-impurity content in product/impurity content in feedstock.
Example 2
An apparatus and method for purifying p-phenylenediamine by fin melt crystallization, the apparatus is shown in FIG. 1.
The method comprises the following steps:
the feed composition is shown in table 3.
Table 3 shows the crude p-phenylenediamine crude material composition in example 2 of the present invention.
TABLE 3 Table 3
| Sub-items | Para-phenylenediamine | M-phenylenediamine | O-phenylenediamine | Totalizing |
| Scheme for the production of a semiconductor device | 89.92 | 4.53 | 5.55 | 100.0 |
(1) Adding liquid p-phenylenediamine raw materials into a fin type melt crystallizer, and controlling the temperature of a purification area and a melting area to keep the temperature of a system at 135-150 ℃;
(2) Controlling the temperature of a purification zone, and cooling the p-phenylenediamine raw material in the step (1) to room temperature at a constant cooling rate, wherein the temperature of a melting zone is kept at 35 ℃ in the process, and dead materials are deducted after balancing for 4 hours to obtain p-phenylenediamine crude crystals;
(3) Controlling the temperature of a purification zone, heating the crude p-phenylenediamine crystals obtained in the step (2) to a sweating temperature at a constant heating rate of 6 ℃/h, keeping the temperature of a melting zone at 135 ℃ in the process, and discharging sweat, namely fraction 1 after balancing for 1h to obtain p-phenylenediamine crystals;
(4) Sweating: heating the p-phenylenediamine crystal product obtained in the step (3) to 137 ℃ above the solidifying point (135 ℃) at a constant heating rate of 4 ℃ to remove the low component, namely fraction 2, so as to obtain p-phenylenediamine crystals with higher components.
(5) Continuously heating the p-phenylenediamine crystals obtained in the step (4) to 139 ℃ at a constant heating rate, and further removing low components to obtain p-phenylenediamine crystals with higher components
(6) And (3) heating the p-phenylenediamine crystals obtained in the step (5) to 160 ℃ to obtain a liquid product, and carrying out the steps (2), (3), (4) and (5) again as raw materials to obtain a second-grade p-phenylenediamine product, and the like, and separating the second-grade p-phenylenediamine product by 6 times until the obtained p-phenylenediamine product meets the purity requirement.
The purity and yield of each stage of p-phenylenediamine liquid product are shown in Table 4.
Table 4 shows the purity and yield of the various stages of para-phenylenediamine liquids in example 2 of the present invention.
TABLE 4 Table 4
Note that: impurity removal = 1-impurity content in product/impurity content in feedstock.
Example 3
An apparatus and method for purifying p-phenylenediamine by fin melt crystallization, the apparatus is shown in FIG. 1.
The method comprises the following steps:
the feed composition is shown in table 5.
Table 5 shows the crude p-phenylenediamine crude material composition in example 3 of the present invention.
TABLE 5
| Sub-items | Para-phenylenediamine | M-phenylenediamine | O-phenylenediamine | Totalizing |
| Scheme for the production of a semiconductor device | 91.98 | 4.02 | 4.00 | 100.0 |
(1) Adding liquid p-phenylenediamine raw materials into a fin type melt crystallizer, and controlling the temperature of a purification area and a melting area to keep the temperature of a system at 135-150 ℃;
(2) Controlling the temperature of a purification zone, and cooling the p-phenylenediamine raw material in the step (1) to room temperature at a constant cooling rate, wherein the temperature of a melting zone is kept at 35 ℃ in the process, and dead materials are deducted after balancing for 4 hours to obtain p-phenylenediamine crude crystals;
(3) Controlling the temperature of a purification zone, heating the crude p-phenylenediamine crystals obtained in the step (2) to a sweating temperature at a constant heating rate of 6 ℃/h, keeping the temperature of a melting zone at 135 ℃ in the process, and discharging sweat, namely fraction 1 after balancing for 1h to obtain p-phenylenediamine crystals;
(4) Sweating: heating the p-phenylenediamine crystal product obtained in the step (3) to 137 ℃ above the solidifying point (135 ℃) at a constant heating rate of 4 ℃ to remove the low component, namely fraction 2, so as to obtain p-phenylenediamine crystals with higher components.
(5) Continuously heating the p-phenylenediamine crystals obtained in the step (4) to 139 ℃ at a constant heating rate, and further removing low components to obtain p-phenylenediamine crystals with higher components
(6) And (3) heating the p-phenylenediamine crystals obtained in the step (5) to 160 ℃ to obtain a liquid product, and carrying out the steps (2), (3), (4) and (5) again as raw materials to obtain a second-grade p-phenylenediamine product, and the like, and separating the second-grade p-phenylenediamine product by 6 times until the obtained p-phenylenediamine product meets the purity requirement.
The purity and yield of each stage of p-phenylenediamine liquid product are shown in Table 6.
Table 6 shows the purity and yield of the various stages of para-phenylenediamine liquids in example 3 of the present invention.
TABLE 6
Note that: impurity removal = 1-impurity content in product/impurity content in feedstock.
While the present invention has been described in detail with respect to an apparatus and method for purifying p-phenylenediamine by fin melt crystallization, specific examples are provided herein to illustrate the principles and embodiments of the present invention and to assist in understanding the method and core concepts of the present invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims. The scope of the patent protection is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims (10)
1. The method for purifying the p-phenylenediamine is characterized by comprising the following steps of:
1) Feeding the liquid p-phenylenediamine raw material into a melting crystallizer, heating and melting, cooling, keeping balance, and removing dead materials in a dead material zone to obtain coarse p-phenylenediamine crystals in the melting crystallizer;
2) Opening a discharge hole at the bottom of the melting crystallizer, heating the p-phenylenediamine crude crystals obtained in the steps to the sweating temperature again, keeping balance, and discharging sweat to obtain p-phenylenediamine crystals;
3) Continuously heating the p-phenylenediamine crystals obtained in the steps to a temperature above the freezing point of the p-phenylenediamine raw material, and discharging impurities from the bottom to obtain the p-phenylenediamine crystals after impurity removal;
4) Continuously heating the p-phenylenediamine crystals obtained in the steps until the p-phenylenediamine crystals reach the vicinity of the solidifying point of the pure p-phenylenediamine, and further discharging impurities to obtain the p-phenylenediamine crystals after further impurity removal;
5) Heating the p-phenylenediamine crystals obtained in the step after further impurity removal again to obtain a liquid product;
6) Repeating the steps 1) to 4) by using the liquid product obtained in the steps to obtain the multi-stage purified p-phenylenediamine.
2. The purification method according to claim 1, wherein the temperature of the heating and melting is 135 to 150 ℃;
the cooling rate is 6-8 ℃/h;
in the step 1), the temperature for keeping balance is 35-45 ℃;
in the step 1), the time for maintaining balance is 3-4 hours;
in the process of the step 1), a discharge hole at the bottom of the melting crystallizer is in a closed state.
3. The purification process of claim 1, wherein the liquid para-phenylenediamine starting material has a purity of from 89% to 95%;
the liquid p-phenylenediamine raw material comprises m-phenylenediamine and/or o-phenylenediamine impurities;
the heating rate of the reheating is 3-8 ℃/h;
the sweating temperature is 130-135 ℃;
the time for maintaining balance is 60-120 min.
4. The purification method according to claim 1, wherein the heating rate of the continuous heating is 3 to 4 ℃;
the solidifying point of the p-phenylenediamine raw material is 135-138 ℃;
the temperature above the solidifying point of the p-phenylenediamine raw material is specifically 5-10 ℃ above the solidifying point of the p-phenylenediamine raw material;
in the step 3), the impurity discharge is specifically to remove low-component impurities;
the p-phenylenediamine crystals after impurity removal comprise higher-component p-phenylenediamine crystals.
5. The purification method according to claim 1, wherein the rate of temperature increase by continuing to increase is 2.5 to 4.5 ℃/h;
the solidifying point of the pure p-phenylenediamine is 139-141 ℃;
the vicinity of the solidifying point of the pure p-phenylenediamine is specifically the solidifying point of the pure p-phenylenediamine which is (+/-) (5-10) DEG C;
in the step 4), the impurities are further discharged, in particular the low-component impurities are further discharged;
the p-phenylenediamine crystals after further impurity removal comprise higher-component p-phenylenediamine crystals;
the multi-stage purified p-phenylenediamine is polymer grade p-phenylenediamine.
6. The purification method according to claim 1, wherein the reheating rate is 1.5 to 2.5 ℃/h;
the reheating is specifically to heat up again until the materials are completely melted;
the temperature of the secondary heating is 145-160 ℃;
the number of repetition is 2-6;
the purity of the p-phenylenediamine after the multistage purification is 99.990-99.995 percent.
7. The p-phenylenediamine purifying device is characterized by comprising a melting crystallizer;
the melting crystallizer is specifically a vertical melting crystallizer with upper inlet and lower outlet;
the melt crystallizer comprises a purification zone and a dead zone from top to bottom.
8. The purification apparatus of claim 7, wherein the melt crystallizer is a neck melt crystallizer;
the melt crystallizer comprises a fin melt crystallizer;
the volume ratio of the purification zone to the dead zone is (18-20): 1.
9. the purification apparatus of claim 7, wherein the dead zone is provided with a spiral screen plate;
the purification zone is provided with a plurality of groups of fin structures in the transverse direction;
the number of the fins of the fin structure is 3-5;
different fins in a group of fins are sequentially adjacent to each other along the height direction of the purification zone.
10. The purification apparatus of claim 9, wherein the distance between adjacent fins in the set of fins is 0.5 to 1.5cm;
the transverse dimension of the fin is 1/3-2/3 of the inner diameter of the purification zone tube;
the melt crystallizer is also provided with an outer jacket for heating.
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