CN108329327B - Purification method of crude pyromellitic dianhydride based on crystal sublimation - Google Patents
Purification method of crude pyromellitic dianhydride based on crystal sublimation Download PDFInfo
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Abstract
The invention provides a purification method of crude pyromellitic dianhydride based on crystal sublimation, which specifically comprises the following steps: directly mixing hot air flow coming out of a reactor taking durene as a raw material with inert gas containing ice wafers, collecting the mixture by a columnar catcher, and centrifuging the mixture to obtain a crude product of the pyromellitic dianhydride; adding a molybdenum trioxide one-dimensional rod-shaped material into a PVP solution, heating for reaction, washing, drying, carbonizing and pickling to obtain a rod-shaped carbon material containing molybdenum oxide; adding the pyromellitic dianhydride crude product into a hydrolysis kettle, adding a rodlike carbon material containing molybdenum oxide, stirring, hydrolyzing, decolorizing, hydrotreating, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal; and (3) carrying out molten salt heating dehydration and sublimation treatment on the crude hydrogenated pyromellitic acid crystal to obtain pyromellitic dianhydride. The purification method of the invention is that the raw material is directly contacted and trapped by inert gas containing ice crystal plates, and then hydrolysis, decoloration and hydrogenation reaction are simultaneously carried out by utilizing rodlike carbon material containing molybdenum oxide, so as to obtain high-purity pyromellitic dianhydride.
Description
Technical Field
The invention belongs to the technical field of purification of pyromellitic dianhydride, and particularly relates to a purification method of crude pyromellitic dianhydride based on crystal sublimation.
Background
Pyromellitic dianhydride is also called as pyromellitic anhydride, has a special molecular structure, can be used for manufacturing materials with heat resistance, electrical insulation and chemical resistance, wherein the main application is to synthesize polyimide plastics by using aromatic diamine and the monomer of polyimide, but the purity requirement of the pyromellitic dianhydride is high and needs to be more than 99%. The prior purification methods of pyromellitic dianhydride include recrystallization, solvent washing, vacuum sublimation, complex, inert gas flow, secondary distillation, etc.
Chinese patent CN 101580509B discloses a method for producing electronic-grade pyromellitic dianhydride from secondary catching crude anhydride, which comprises mixing and heating the secondary catching crude anhydride and a solvent for washing, cooling, suction filtering, dehydrating and decolorizing to obtain a crystal solid, cooling and crystallizing the crystal solid again, suction filtering to obtain pyromellitic dianhydride crystal containing mother liquor, drying, cooling to obtain electronic-grade pyromellitic dianhydride, and recycling the crystallized mother liquor. The method takes secondary catching crude anhydride which is produced by carrying out secondary catching on crude pyromellitic acid of durene through gas-phase catalytic oxidation as a raw material, phthalic anhydride, trimellitic anhydride, pyromellitic acid, pyromellitic monoanhydride, 5-methyl trimellitic anhydride, mechanical impurities and superfine foreign matters contained in the crude pyromellitic acid are taken as raw materials, the purification method of the invention is carried out in a closed device, the environmental pollution is small, the mother liquor is recycled, the defect of a hydrolysis method is overcome, the purity of the purified pyromellitic acid is higher than 99 percent, and the purity grade requirement of the electronic grade PI film is compounded and synthesized. The preparation method of the electronic-grade hydrogenated pyromellitic dianhydride disclosed in the Chinese patent CN103992330B comprises the steps of adding pyromellitic dianhydride with the purity of more than 98%, deionized water and a catalyst containing noble metal carbon into a high-pressure kettle, introducing hydrogen into the reaction kettle to simultaneously carry out hydrolysis and catalytic hydrogenation reaction to obtain crude hydrogenated pyromellitic dianhydride, then carrying out decoloration and refining on the crude hydrogenated pyromellitic dianhydride by using deionized water and activated carbon to obtain hydrogenated pyromellitic dianhydride with the purity of more than 99.5%, and finally carrying out dehydration reaction by using acetic anhydride to obtain the electronic-grade hydrogenated pyromellitic dianhydride with the purity of more than 99.85%. As can be seen from the above prior art, the purification efficiency and purity of pyromellitic dianhydride can be improved by improving the trapping process, but many of the methods are still not mature enough and need to be further improved.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a purification method of crude pyromellitic dianhydride based on crystallization sublimation, wherein hot air flow from a reactor using durene as a raw material is directly contacted and trapped with inert gas containing ice crystal pieces, and a bar-shaped carbon material containing molybdenum oxide is simultaneously used for hydrolysis, decoloration and hydrogenation reaction to obtain high-purity pyromellitic dianhydride.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a purification method of crude pyromellitic dianhydride based on crystal sublimation is characterized in that: the method comprises the following steps:
(1) directly mixing hot air flow coming out of a reactor taking durene as a raw material with inert gas containing ice wafers, collecting the mixture by a columnar catcher, and centrifuging the mixture to obtain a crude product of the pyromellitic dianhydride;
(2) adding the pyromellitic dianhydride crude product prepared in the step (1) into a hydrolysis kettle, adding a rod-shaped carbon material containing molybdenum oxide, stirring, hydrolyzing, decolorizing, hydrotreating, and filtering to obtain a crude hydrogenated pyromellitic acid crystal;
(3) and (3) carrying out molten salt heating dehydration and sublimation treatment on the crude hydrogenated pyromellitic acid crystal prepared in the step (2) to obtain pyromellitic dianhydride.
Preferably, in the step (1), the volume ratio of the hot gas flow to the inert gas with the ice crystal plates is 1: 0.5-0.8.
Preferably, in the step (1), the ice crystal piece content of the inert gas containing ice pieces is 1 to 4%, and the gas velocity is 0.05 to 0.5 m/s.
Preferably, in the step (2), the temperature of the steam in the hydrolysis kettle is 90-100 ℃, and the pressure is 0.2 MPa.
As a preferable mode of the above aspect, in the step (2), the method for producing a rod-like carbon material containing molybdenum oxide includes: adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 120-130 ℃ for reaction for 2-3d, taking out crystals, washing, vacuum drying, carbonizing at 590-620 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
Preferably, in the step (2), the amount of the rod-like carbon material containing molybdenum oxide is 1-5% of the mass of the crude pyromellitic dianhydride.
Preferably, in the step (2), the time for hydrolysis, decolorization and hydrogenation treatment is 3-6 h.
Preferably, in the step (3), the processes of molten salt heating dehydration and sublimation treatment include: firstly, under the pressure of-0.09 MPa, the temperature is raised to 230 ℃ for 220 ℃ at the speed of 10-20 ℃/min, the temperature is preserved for 30-60min, then the temperature is raised to 250 ℃ for 240 ℃ at the speed of 1-3 ℃/min, and the temperature is preserved for 60-120 min.
Preferably, in the step (3), the molten salt is a mixture of potassium nitrate and sodium nitrate.
Preferably, in the step (3), the purity of pyromellitic dianhydride is greater than 99.8%.
Compared with the prior art, the invention has the following beneficial effects:
(1) the hot air flow coming out of the reactor using durene as raw material is directly contacted with the inert gas containing ice crystal plates, the hot air flow is condensed and desublimated to crystallize, and compared with water contact cooling, the cooling effect is better, the conversion of durene into propylene glycol methyl ether acetate is reduced, and the weight of ice crystal plates reduces the crystallization condition of the crude durene tetracarboxylic acid crystals on the wall surface, and a columnar catcher is adopted for collection, the heat exchange effect is good, the cooling speed is high, the yield is higher, and the cooling gas also contains the inert gas, thereby reducing the water and effect of anhydride converted into acid, and further improving the yield of the product. The collected crude pyromellitic dianhydride is subjected to hydrolysis, decoloration and hydrogenation reaction simultaneously by utilizing a rodlike carbon material containing molybdenum oxide, the rodlike carbon material containing molybdenum oxide is a rodlike material, the specific surface area is large, the hydrogenation catalytic activity is high, and the porous carbon material has a certain decoloration effect, so that the hydrolysis, decoloration and hydrogenation are simultaneously carried out, the reaction time is shortened, the reaction efficiency and the product purity are improved, and the continuous reaction is facilitated.
(2) The preparation method is simple, takes the rod-shaped carbon material containing molybdenum oxide as a catalyst, and simultaneously carries out hydrolysis, decoloration and hydrogenation reaction, thereby having high extraction efficiency, high product purity, strong controllability, few byproducts and high product purity.
Detailed Description
The present invention will be described in detail with reference to specific embodiments, which are illustrative of the invention and are not to be construed as limiting the invention.
Example 1:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has a volume ratio of 1:0.5 with inert gas containing ice wafers, wherein the content of ice crystal plates in the inert gas containing the ice wafers is 1%, and the gas velocity is 0.05m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 120 ℃ for reaction for 2d, taking out crystals, washing, drying in vacuum, carbonizing at 590 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 90 ℃, the pressure is 0.2MPa, adding a rod-shaped carbon material containing molybdenum oxide, the amount of which is 1% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing, hydrogenating for 3 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1:1, heating to 220 ℃ at the speed of 10 ℃/min under the pressure of-0.09 MPa, preserving heat for 30min, heating to 240 ℃ at the speed of 1 ℃/min, preserving heat for 60min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
Example 2:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has a volume ratio of 1: 0.8 with inert gas containing ice wafers, wherein the content of the ice wafers in the inert gas containing the ice wafers is 4%, and the gas velocity is 0.5m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 130 ℃, reacting for 3d, taking out crystals, washing, drying in vacuum, carbonizing at 620 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 100 ℃, the pressure is 0.2MPa, adding a rod-shaped carbon material containing molybdenum oxide, the amount of which is 5% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing, hydrogenating for 6 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by using a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1: 1.5, heating to 230 ℃ at the speed of 20 ℃/min under the pressure of-0.09 MPa, preserving heat for 60min, heating to 250 ℃ at the speed of 3 ℃/min, preserving heat for 120min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
Example 3:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has the volume ratio of 1:0.6 with inert gas containing ice wafers, wherein the content of the ice crystal plates in the inert gas containing the ice wafers is 2 percent, the gas velocity is 0.15m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 125 ℃ for reaction for 2.5d, taking out crystals, washing, drying in vacuum, carbonizing at 600 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 95 ℃, the pressure is 0.2MPa, adding a rod-shaped carbon material containing molybdenum oxide, the amount of which is 2% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing, hydrogenating for 4 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1:1.3, heating to 225 ℃ at the speed of 15 ℃/min under the pressure of-0.09 MPa, preserving heat for 45min, heating to 245 ℃ at the speed of 2 ℃/min, preserving heat for 80min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
Example 4:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has a volume ratio of 1:0.7 with inert gas containing ice wafers, wherein the content of the ice wafers in the inert gas containing the ice wafers is 2.5%, and the gas velocity is 0.3m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 128 ℃ for reaction for 2d, taking out crystals, washing, drying in vacuum, carbonizing at 610 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 95 ℃, the pressure is 0.2MPa, adding a rodlike carbon material containing molybdenum oxide, the amount of which is 4% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing, hydrogenating for 5 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1:1.4, heating to 225 ℃ at the speed of 13 ℃/min under the pressure of-0.09 MPa, preserving heat for 40min, heating to 246 ℃ at the speed of 2.5 ℃/min, preserving heat for 90min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
Example 5:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has a volume ratio of 1:0.5 with inert gas containing ice wafers, wherein the content of the ice wafers in the inert gas containing the ice wafers is 4%, and the gas velocity is 0.05m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 130 ℃ for reaction for 2d, taking out crystals, washing, drying in vacuum, carbonizing at 620 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 90 ℃, the pressure is 0.2MPa, adding a rod-shaped carbon material containing molybdenum oxide, the amount of which is 5% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing, hydrogenating for 3 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by using a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1: 1.5, heating to 230 ℃ at the speed of 10 ℃/min under the pressure of-0.09 MPa, preserving heat for 30min, heating to 240 ℃ at the speed of 3 ℃/min, preserving heat for 120min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
Example 6:
(1) directly mixing hot air flow which is discharged from a reactor taking durene as a raw material and has a volume ratio of 1: 0.8 with inert gas containing ice wafers, wherein the content of ice crystal plates in the inert gas containing the ice wafers is 1%, and the gas velocity is 0.5m/s, collecting by a columnar catcher, and centrifuging to obtain a crude product of the pyromellitic dianhydride.
(2) Adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 120 ℃ for reaction for 3d, taking out crystals, washing, drying in vacuum, carbonizing at 590 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
(3) Adding the pyromellitic dianhydride crude product into a hydrolysis kettle, wherein the temperature of steam in the hydrolysis kettle is 100 ℃, the pressure is 0.2MPa, adding a rod-shaped carbon material containing molybdenum oxide, the amount of which is 1% of the mass of the pyromellitic dianhydride crude product, stirring, hydrolyzing, decolorizing and hydrogenating for 6 hours, and filtering to obtain a crude hydrogenated pyromellitic dianhydride crystal.
(4) Carrying out molten salt treatment on the crude hydrogenated pyromellitic acid crystal by a mixture of potassium nitrate and sodium nitrate according to the mass ratio of 1:1, heating to 220 ℃ at the speed of 20 ℃/min under the pressure of-0.09 MPa, preserving heat for 60min, heating to 250 ℃ at the speed of 1 ℃/min, preserving heat for 60min, and carrying out heating dehydration and sublimation treatment to obtain pyromellitic dianhydride.
As a result of examination, the purity and yield of pyromellitic dianhydride prepared in examples 1 to 6 were as follows:
| example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | |
| Purity (%) | 99.83 | 99.85 | 99.89 | 99.86 | 99.82 | 99.83 |
| Yield (%) | 99.3 | 99.6 | 99.5 | 99.4 | 99.5 | 99.6 |
As can be seen from the above table, the purification method of the present invention based on crystal sublimation of crude pyromellitic dianhydride produces pyromellitic dianhydride with high purity and yield.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (9)
1. A purification method of crude pyromellitic dianhydride based on crystal sublimation is characterized in that: the method comprises the following steps:
(1) directly mixing hot air flow coming out of a reactor taking durene as a raw material with inert gas containing ice wafers, collecting the mixture by a columnar catcher, and centrifuging the mixture to obtain a crude product of the pyromellitic dianhydride;
(2) adding the pyromellitic dianhydride crude product prepared in the step (1) into a hydrolysis kettle, adding a rod-shaped carbon material containing molybdenum oxide, stirring, hydrolyzing, decolorizing, hydrotreating, and filtering to obtain a crude hydrogenated pyromellitic acid crystal;
(3) carrying out molten salt heating dehydration and sublimation treatment on the crude hydrogenated pyromellitic acid crystal prepared in the step (2) to obtain pyromellitic dianhydride;
in the step (2), the preparation method of the rod-like carbon material containing molybdenum oxide comprises the following steps: adding the molybdenum trioxide one-dimensional rod-shaped material into PVP solution, heating to 120-130 ℃ for reaction for 2-3d, taking out crystals, washing, vacuum drying, carbonizing at 590-620 ℃, and pickling with hydrofluoric acid to obtain the molybdenum oxide-containing rod-shaped carbon material.
2. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (1), the volume ratio of the hot air flow to the inert gas with the ice crystal plates is 1: 0.5-0.8.
3. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (1), the content of ice crystal plates in the inert gas containing the ice crystal plates is 1-4%, and the gas velocity is 0.05-0.5 m/s.
4. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (2), the temperature of steam in the hydrolysis kettle is 90-100 ℃, and the pressure is 0.2 MPa.
5. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (2), the consumption of the rodlike carbon material containing molybdenum oxide is 1-5% of the mass of the pyromellitic dianhydride crude product.
6. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (2), the time of hydrolysis, decoloration and hydrotreatment is 3-6 h.
7. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (3), the molten salt heating dehydration and sublimation treatment process comprises the following steps: firstly, under the pressure of-0.09 MPa, the temperature is raised to 230 ℃ for 220 ℃ at the speed of 10-20 ℃/min, the temperature is preserved for 30-60min, then the temperature is raised to 250 ℃ for 240 ℃ at the speed of 1-3 ℃/min, and the temperature is preserved for 60-120 min.
8. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (3), the molten salt is a mixture of potassium nitrate and sodium nitrate.
9. The purification method of crude pyromellitic dianhydride based on sublimation crystallization according to claim 1, wherein: in the step (3), the purity of the pyromellitic dianhydride is more than 99.8%.
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| EP1464393A1 (en) * | 1999-02-19 | 2004-10-06 | Nippon Shokubai Co., Ltd. | Catalyst for producing phthalic anhydride |
| CN101037439A (en) * | 2007-04-23 | 2007-09-19 | 东北师范大学 | Production technique of benzenetetracarboxylic dianhydride by catalyzing carrier-type polyoxometalates |
| CN101580509B (en) * | 2009-06-03 | 2011-02-02 | 常熟市联邦化工有限公司 | Method for producing electronic-grade pyromellitic dianhydride from secondary trapped coarse anhydride |
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Address after: Room 312, Building 2, Small and Medium-sized Enterprise Park, Jiangsu Avenue, Xuwei New District, Lianyungang City, Jiangsu Province, 222000 Applicant after: Lianyungang Peng Chen special new material Co., Ltd. Address before: 215225 99.6 km of Meiyan 318 National Highway, Pingwang Town, Wujiang District, Suzhou City, Jiangsu Province Applicant before: Lianyungang Peng Chen special new material Co., Ltd. |
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Denomination of invention: A purification method of crude pyromellitic dianhydride based on crystal sublimation Effective date of registration: 20210918 Granted publication date: 20200714 Pledgee: Bank of Nanjing Co.,Ltd. Lianyungang Branch Pledgor: LIANYUNGANG PENGCHEN SPECIAL NEW MATERIAL Co.,Ltd. Registration number: Y2021320000235 |