CN117258687A - Dehydration method of raw materials in polyphenylene sulfide production and production method of polyphenylene sulfide - Google Patents
Dehydration method of raw materials in polyphenylene sulfide production and production method of polyphenylene sulfide Download PDFInfo
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- 238000006297 dehydration reaction Methods 0.000 title claims abstract description 184
- 230000018044 dehydration Effects 0.000 title claims abstract description 169
- 239000004734 Polyphenylene sulfide Substances 0.000 title claims abstract description 54
- 229920000069 polyphenylene sulfide Polymers 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000002994 raw material Substances 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 230000019086 sulfide ion homeostasis Effects 0.000 title claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 96
- 239000002798 polar solvent Substances 0.000 claims abstract description 90
- 239000007788 liquid Substances 0.000 claims abstract description 89
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 77
- 238000010438 heat treatment Methods 0.000 claims abstract description 49
- 239000007864 aqueous solution Substances 0.000 claims abstract description 24
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 24
- 230000008569 process Effects 0.000 claims description 17
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 7
- 239000003960 organic solvent Substances 0.000 claims description 5
- AVQQQNCBBIEMEU-UHFFFAOYSA-N 1,1,3,3-tetramethylurea Chemical compound CN(C)C(=O)N(C)C AVQQQNCBBIEMEU-UHFFFAOYSA-N 0.000 claims description 4
- GNOIPBMMFNIUFM-UHFFFAOYSA-N hexamethylphosphoric triamide Chemical compound CN(C)P(=O)(N(C)C)N(C)C GNOIPBMMFNIUFM-UHFFFAOYSA-N 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 32
- 239000011593 sulfur Substances 0.000 description 32
- 229910052717 sulfur Inorganic materials 0.000 description 32
- 230000000052 comparative effect Effects 0.000 description 19
- 229910052979 sodium sulfide Inorganic materials 0.000 description 19
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 19
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 16
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 16
- 239000007789 gas Substances 0.000 description 15
- 238000006116 polymerization reaction Methods 0.000 description 14
- 239000006260 foam Substances 0.000 description 7
- 239000012046 mixed solvent Substances 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- IHYNKGRWCDKNEG-UHFFFAOYSA-N n-(4-bromophenyl)-2,6-dihydroxybenzamide Chemical compound OC1=CC=CC(O)=C1C(=O)NC1=CC=C(Br)C=C1 IHYNKGRWCDKNEG-UHFFFAOYSA-N 0.000 description 5
- OCJBOOLMMGQPQU-UHFFFAOYSA-N 1,4-dichlorobenzene Chemical compound ClC1=CC=C(Cl)C=C1 OCJBOOLMMGQPQU-UHFFFAOYSA-N 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 239000003513 alkali Substances 0.000 description 2
- 229940124277 aminobutyric acid Drugs 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- BTCSSZJGUNDROE-UHFFFAOYSA-N gamma-aminobutyric acid Chemical compound NCCCC(O)=O BTCSSZJGUNDROE-UHFFFAOYSA-N 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 230000018199 S phase Effects 0.000 description 1
- ZCNSUVCCASIJIM-UHFFFAOYSA-N [Na].CNCCCC(=O)O Chemical compound [Na].CNCCCC(=O)O ZCNSUVCCASIJIM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000008258 liquid foam Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920013636 polyphenyl ether polymer Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
- C08G75/02—Polythioethers
- C08G75/0204—Polyarylenethioethers
- C08G75/025—Preparatory processes
- C08G75/0259—Preparatory processes metal hydrogensulfides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
- B01D19/02—Foam dispersion or prevention
- B01D19/04—Foam dispersion or prevention by addition of chemical substances
- B01D19/0404—Foam dispersion or prevention by addition of chemical substances characterised by the nature of the chemical substance
- B01D19/0413—Foam dispersion or prevention by addition of chemical substances characterised by the nature of the chemical substance compounds containing N-atoms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/10—Vacuum distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
- B01J19/0013—Controlling the temperature of the process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/006—Processes utilising sub-atmospheric pressure; Apparatus therefor
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Toxicology (AREA)
- Dispersion Chemistry (AREA)
- Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)
Abstract
The invention relates to a dehydration method of raw materials in polyphenylene sulfide production and a production method of polyphenylene sulfide, which comprises the following steps: placing sodium hydrosulfide aqueous solution, alkaline aqueous solution and first polar solvent into a reaction device to ensure that the filling degree of the reaction device is 80% -85%, then heating and raising the temperature to obtain a dehydration liquid system, and then decompressing and maintaining the pressure in the reaction device to be 30-50 kPa; and heating and dehydrating the dehydrated liquid system, and stopping dehydrating when the dehydrated liquid system is dehydrated to a preset water content condition, wherein when the liquid level of the dehydrated liquid is foamed, a second polar solvent is added into the dehydrated liquid system, the surface tension of the second polar solvent is smaller than that of water, and the filling degree of the reaction device is controlled to be maintained at 80% -86%. The dehydration method can fully utilize the volume of the reaction device, improve the dehydration efficiency, reduce the loss of raw materials, ensure the balance of the raw material proportion and further improve the yield and the quality of the polyphenylene sulfide.
Description
Technical Field
The invention relates to the technical field of polyphenylene sulfide, in particular to a dehydration method of raw materials in the production of polyphenylene sulfide and a production method of polyphenylene sulfide.
Background
Currently, the most common synthetic route in the production of commercial polyphenylene sulfide (PPS) is the sodium sulfide process. In the process of synthesizing polyphenylene sulfide by sodium sulfide, dehydration reaction is involved, in the dehydration reaction, a dehydration method of normal pressure or first holding pressure and then normal pressure is adopted in an inert gas atmosphere by adopting sodium hydrosulfide (NaHS) solution, liquid alkali (NaOH) and N-methylpyrrolidone (NMP), and the dehydration end point temperature is generally controlled to be more than 200 ℃ for dehydration until the water content in the system is controlled to be within a rated range for the next polymerization reaction.
Typically, the dehydration reaction initiation stage system consists of two phases, namely NMP phase/Na phase 2 S phase, NMP is hydrolyzed into N-methyl-4-aminobutyric acid Sodium (SMAB) in a large amount along with the rising of dehydration reaction temperature in an alkaline environment to form SMAB-NaSH complex, the material can directly lead to the great loss of NMP solvent, the comprehensive production cost is greatly increased, and PPS resin synthesized by reacting with p-dichlorobenzene (PDCB) in the polymerization stage has high volatilization and heatThe stability is low, thereby being unfavorable for the application of PPS resin in the preparation of fiber, film, monofilament and the like.
Meanwhile, a dehydration method of normal pressure or pressure building and normal pressure is adopted, so that sulfur loss in the dehydration reaction is often increased, and the fluctuation of the water content of the system is large, so that the polymerization reaction is directly influenced. In addition, the dehydration method under normal pressure or after the pressure is held back is carried out under high temperature and strong alkali, so that the corrosion to reaction equipment is serious, and the generated metal rust slag can directly influence the quality of the product. In addition, in the preparation method of polyphenylene sulfide, the dehydration operation is carried out under normal pressure or after pressure is built up, the dehydration reaction time is generally 3-5 hours, the polymerization time is 6-24 hours, and the reaction efficiency is low, so that in order to improve the continuous degree of dehydration polymerization and improve the utilization efficiency of a dehydration polymerization kettle, one dehydration kettle is usually matched with a plurality of polymerization kettles for use.
With the improvement of the polymerization process, the polymerization speed is greatly improved, namely, the polymerization efficiency is improved, however, the dehydration efficiency is not sufficiently improved, and the bottleneck of improving the overall yield is formed.
In order to improve the dehydration reaction efficiency, the dehydration reaction speed and the single-batch dehydration filling degree can be improved. Among them, in order to increase the dehydration reaction rate, reduced pressure dehydration is generally used such that evaporation of water in a solution is advantageous in accelerating the dehydration progress by formation and collapse of bubbles, but a large amount of bubbles or bumping, particularly bubbles, are easily formed during the reduced pressure dehydration, resulting in an increase in the frothing height, thereby having to decrease the liquid filling amount of the dehydration tank. Meanwhile, in the decompression dehydration process, raw materials in the solution can be taken away from the reaction kettle together with the evaporation of water vapor in bubbles, so that the load of a dehydration rectifying tower is increased, the loss of raw materials and unbalance of the proportion are caused, and the yield and quality of polyphenylene sulfide are further reduced.
Disclosure of Invention
In view of the foregoing, it is necessary to provide a method for dehydrating a raw material in the production of polyphenylene sulfide, which can effectively avoid an increase in the height of dehydrated liquid foam, improve the dehydration efficiency while fully utilizing the volume of a reaction apparatus, reduce the loss of raw materials, ensure the balance of the raw material ratios, and further improve the yield and quality of polyphenylene sulfide, and a method for producing polyphenylene sulfide.
A method for dehydrating raw materials in the production of polyphenylene sulfide, comprising the following steps:
placing sodium hydrosulfide aqueous solution, alkaline aqueous solution and first polar solvent into a reaction device to ensure that the filling degree of the reaction device is 80% -85%, then heating and raising the temperature to obtain a dehydration liquid system, and then decompressing and maintaining the pressure in the reaction device to be 30-50 kPa;
and heating and dehydrating the dehydrated liquid system, and stopping dehydrating when the dehydrated liquid system is dehydrated to a preset water content condition, wherein when the liquid level of the dehydrated liquid is foamed, a second polar solvent is added into the dehydrated liquid system, the surface tension of the second polar solvent is smaller than that of water, and the filling degree of the reaction device is controlled to be maintained at 80% -86%.
In one embodiment, the molar ratio of the first polar solvent to the aqueous sodium hydrosulfide is 1.6:1 to 1.8:1;
and/or the molar ratio of the alkaline aqueous solution to the sodium hydrosulfide aqueous solution is 1.01:1-1.03:1.
In one embodiment, the mass ratio of the first polar solvent to the second polar solvent is 0.9:1 to 1.1:1;
and/or, the difference in surface tension between the second polar solvent and the water is 30mN/m to 40mN/m.
In one embodiment, the first polar solvent and the second polar solvent are the same.
In one embodiment, the rate of depressurization is from 1.8kPa/min to 2.4kPa/min during the period of depressurization and maintaining the pressure of the dehydrated liquid system at 30kPa to 50kPa.
In one embodiment, in the step of heating and dehydrating the dehydration liquid system, the heating rate is 0.8 ℃/min-1.1 ℃/min;
and/or, in the step of heating and dehydrating the dehydration liquid system, the temperature of heating and dehydrating is 140-160 ℃.
In one embodiment, during the heating and temperature raising treatment, the temperature is raised to 90-110 ℃ and the heating and temperature raising time is 0.4-0.6 h.
In one embodiment, the first polar solvent and the second polar solvent are both selected from an organic solvent selected from at least one of N-methylpyrrolidone, tetramethylurea, hexamethylphosphoric triamide;
and/or the alkaline aqueous solution is selected from sodium hydroxide aqueous solution and/or potassium hydroxide aqueous solution.
In one embodiment, the second polar solvent is added to the dehydrated liquid system by spraying.
The method for producing the polyphenylene sulfide adopts the method for dehydrating the raw materials in the production of the polyphenylene sulfide to dehydrate the raw materials.
In the dehydration method of raw materials in the production of polyphenylene sulfide, a first polar solvent, a sodium hydrosulfide aqueous solution and an alkaline aqueous solution are firstly placed in a reaction device to be mixed and subjected to neutralization reaction to generate sodium sulfide, and then under the condition of heating and temperature rising, the sodium sulfide is completely dissolved in water and the first polar solvent to form a dehydration liquid system; meanwhile, the pressure of the reaction device is reduced and maintained to be 30kPa-50kPa, compared with normal pressure, the setting can reduce the end temperature of dehydration, shorten the dehydration time and further improve the dehydration efficiency; in addition, through carrying out the rising temperature dehydration to the dehydration liquid system, in this process, through adding the second polar solvent, utilize the surface tension of second polar solvent far less than the surface tension's of water characteristic, the bubble that produces in the dehydration process contacts with the second polar solvent and takes place to break, avoided leading to the increase of foaming height because of a large amount of bubbles, make the filling degree of whole reaction unit maintain 80% -86%, thereby, can improve dehydration efficiency when the capacity of make full use of reaction unit, reduce the raw materials loss, guaranteed the balance of raw materials ratio, and then improve polyphenylene sulfide's productivity and quality.
Detailed Description
The present invention will be described in more detail below in order to facilitate understanding of the present invention. It should be understood, however, that the invention may be embodied in many different forms and is not limited to the implementations or embodiments described herein. Rather, these embodiments or examples are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention.
The invention provides a dehydration method of raw materials in polyphenylene sulfide production, which comprises the following steps:
the sodium hydrosulfide aqueous solution, the alkaline aqueous solution and the first polar solvent are placed in a reaction device so that the filling degree of the reaction device is 80% -85%, then heating and heating treatment is carried out to obtain a dehydration liquid system, and then the pressure in the reaction device is reduced and maintained to be 30-50 kPa. Specifically, an aqueous sodium bisulfide solution, an alkaline aqueous solution and a first polar solvent are placed in a reaction device, so that the filling degree of the reaction device is 80% -85%, at this time, alkaline substances (such as alkaline hydroxide) and sodium bisulfide can undergo a neutralization reaction to generate sodium sulfide and water, as sodium sulfide is easily dissolved in water to form a saturated aqueous sodium sulfide solution, sodium sulfide solid still is partially separated out, and at the same time, part of sodium sulfide can be hydrolyzed to generate hydrogen sulfide gas and sodium hydroxide, so that the system is alkaline, and as heating and heating are carried out, part of the first polar solvent (such as NMP) can be hydrolyzed under alkaline conditions to form N-methyl-4-sodium aminobutyric acid, and the N-methyl-4-sodium aminobutyric acid can form a complex with sodium sulfide under the action of water, so that sodium sulfide is completely dissolved in a mixed solvent of water and the first polar solvent, namely, a dehydration liquid system is obtained. Meanwhile, the pressure in the reaction device is changed from the normal pressure state to 30kPa-50kPa through decompression, and the pressure in the reaction device is maintained to be 30kPa-50kPa, so that compared with the normal pressure, the setting can reduce the end temperature of dehydration, shorten the dehydration time and further improve the dehydration efficiency. In addition, since the heating treatment is performed at first, a dehydrated liquid system is obtained, and then the pressure reduction treatment is performed. By the arrangement, a large amount of foaming and bumping can be avoided.
Alternatively, the molar ratio of the first polar solvent to the aqueous sodium bisulfide is 1.6:1-1.8:1, preferably 1.75, and the molar ratio of the alkaline aqueous solution to the aqueous sodium bisulfide is 1:1-1.05:1, preferably 1.01:1-1.03:1, further preferably 1.015. The setting can further ensure that the filling degree of the reaction device is 80% -85%, and at the same time, sodium bisulfide and alkaline substances react to generate enough sodium sulfide, and the sodium sulfide can be better dissolved in water and polar solvents to form a stable dehydration liquid system.
Alternatively, the alkaline aqueous solution is selected from aqueous sodium hydroxide and/or aqueous potassium hydroxide, preferably aqueous sodium hydroxide.
Optionally, the mass fraction of solute in the alkaline aqueous solution is 40% -48%; the mass fraction of sodium hydrosulfide in the sodium hydrosulfide aqueous solution is 38% -45%.
In one embodiment, the reaction apparatus is subjected to a reduced pressure treatment while stirring. By the arrangement, the occurrence of bumping can be further prevented.
In an embodiment, the reaction device may be a reaction kettle or a reduced pressure rectification column.
Alternatively, the rate of depressurization is 1.8kPa/min to 2.4kPa/min during the period of depressurization and maintaining the pressure of the dehydrated liquid system at 30kPa to 50kPa. By the arrangement, the boiling point of water is reduced, the subsequent dehydration efficiency is improved, and meanwhile, the first polar solvent or the subsequent second polar solvent is prevented from being extracted in a large amount, so that the raw materials and the solvent are unbalanced in proportion, and the yield and the quality of the polyphenylene sulfide are further influenced.
Optionally, in the heating and temperature raising process, the temperature is raised to 90-110 ℃ and the heating and temperature raising time is 0.4-0.6 h. By the arrangement, sodium sulfide generated by the reaction can be further fully dissolved in the mixed solvent of water and the first polar solvent, so that hydrogen sulfide gas generated by hydrolysis of sodium sulfide is brought out by steam in the dehydration process, loss of total sulfur in a system is reduced, balance of raw material proportion is ensured, and dehydration efficiency and yield of polyphenylene sulfide are improved.
The dehydration method of raw materials in the production of polyphenylene sulfide comprises the steps of heating and dehydrating the obtained dehydrated liquid system under a pressure maintaining state, and stopping dehydration when the dehydration is carried out to a preset water content condition, wherein when the liquid level of the dehydrated liquid is foamed, a second polar solvent is added into the dehydrated liquid system, the surface tension of the second polar solvent is smaller than that of water, and the filling degree of a reaction device is controlled to be maintained at 80% -86%.
Specifically, when foam appears on the liquid surface of the dehydration liquid, the characteristic that the surface tension of the second polar solvent is far smaller than that of water is utilized by adding the second polar solvent, so that bubbles generated in the dehydration process are caused to contact with the second polar solvent to be broken, the increase of the foam-making height caused by a large amount of bubbles is avoided, the filling degree of the whole reaction device is maintained at 80% -86%, the dehydration efficiency is improved while the volume of the reaction device is fully utilized, the raw material loss is reduced, the balance of the raw material proportion is ensured, and the yield and the quality of the polyphenylene sulfide are further improved.
Optionally, the mass ratio of the first polar solvent to the second polar solvent is 0.8:1 to 1.2:1, preferably 0.9:1 to 1.1:1, and further preferably 1.0; the first polar solvent and the second polar solvent are both selected from organic solvents, and the organic solvents are at least one selected from N-methyl pyrrolidone, tetramethylurea and hexamethylphosphoric triamide, and preferably N-methyl pyrrolidone. By the arrangement, the increase of the foam-making height on the surface of the dehydration liquid can be better avoided, the filling degree of the reaction device is further controlled to be maintained at 80% -86%, the volume of the reaction device is fully utilized, the dehydration rate is further improved, and the loss of raw materials is reduced.
Alternatively, the difference in surface tension between the second polar solvent and the water is 30mN/m-40mN/m, preferably 32mN/m-38mN/m. By the arrangement, the breaking speed of bubbles in the dehydration liquid can be increased, and the dehydration efficiency is further improved.
The first polar solvent and the second polar solvent may be the same or different. In the present invention, the first polar solvent and the second polar solvent are preferably the same. So set up, the recovery of the polar solvent of being convenient for.
The boiling point of water can be reduced by reducing the pressure, so that the required dehydration temperature of the whole dehydration liquid system can be reduced, and optionally, in the step of heating and dehydrating the dehydration liquid system, the heating and dehydration temperature is 140-160 ℃, preferably 150 ℃. By the arrangement, the dehydration rate can be further improved, and meanwhile, the energy consumption is reduced.
Further, in the step of heating and dehydrating the dehydration liquid system, the heating rate is 0.8 ℃/min-1.1 ℃/min, preferably 1.0 ℃/min. By the arrangement, the temperature of the whole dehydration liquid system is further uniform, and the dehydration rate is further improved.
Optionally, the second polar solvent is added to the dehydrated liquid system by spraying. This arrangement facilitates the second polar solvent to absorb a portion of the volatilized sulfur species (e.g., hydrogen sulfide gas) and carry it back into the dehydration liquid system, thereby further reducing the loss of sulfur species (e.g., hydrogen sulfide) and thus reducing the sulfur loss rate.
In one embodiment, the dehydration to a predetermined water content condition refers to a water to total sulfur molar ratio in the dehydrated liquid system of 1.1:1 to 1.25:1, preferably 1.15:1. The arrangement is favorable for the subsequent polymerization reaction, and further improves the yield and quality of the polyphenyl ether resin. It will be appreciated that the molar amount of water is from 1.1 to 1.25 based on 1mo1 total sulfur; meanwhile, the molar amount of total sulfur refers to the molar amount of all sulfur in the entire dehydrated liquid system. In one embodiment, during the temperature-rising dehydration process, the water content in the dehydration liquid system is detected by sampling or the water content in the dehydration system is detected rapidly by adopting a water titration instrument.
In one embodiment, a radiation level gauge or a radar level gauge is used for detecting foam in the liquid level of the dewatering liquid.
The reaction device is communicated with the dehydration rectifying tower, so that a small amount of the first polar solvent or the second polar solvent volatilized in the dehydration liquid system can be separated by the dehydration rectifying tower and then recycled to the reaction device.
Meanwhile, the invention also provides a production method of the polyphenylene sulfide, and the raw material is dehydrated by adopting the dehydration method of the raw material in the production of the polyphenylene sulfide. The production method of the polyphenylene sulfide can well avoid the increase of the foam height caused by a large number of bubbles, so that the filling degree of the whole reaction device is maintained at 80% -86%, the dehydration efficiency can be improved while the volume of the reaction device is fully utilized, the loss of raw materials is reduced, the balance of the raw material proportion is ensured, and the yield and the quality of the polyphenylene sulfide are further improved.
Hereinafter, a dehydration method of the raw material in the production of polyphenylene sulfide and a production method of polyphenylene sulfide will be further described by the following specific examples.
Meanwhile, the raw materials and reagents involved in the examples and comparative examples of the present invention are commercially available.
Example 1
35.7kg (360 mo 1) of a first polar solvent (N-methylpyrrolidone), 28.0kg (200 mo 1) of an aqueous sodium hydrosulfide solution (mass fraction: 40%) and 19.2kg (202 mo 1) of an aqueous sodium hydroxide solution (mass fraction: 42%) were mixed in a reaction vessel, at which time the filling degree of the reaction vessel was 83.0%, and the reaction vessel was connected to a dehydration rectifying column; heating for 0.5h to 95 ℃ under stirring, wherein sodium sulfide in the reaction kettle is completely dissolved in a mixed solvent consisting of water and a first polar solvent, and thus a dehydration liquid system is obtained.
Then, the dehydration liquid system is dehydrated by reducing the pressure and maintaining the pressure in the reaction kettle to be 40kPa, wherein the reducing rate is 2.0kPa/min, and the temperature is increased to 150 ℃ under the pressure, and the heating rate is 0.9 ℃/min; in the process, when foam appears on the liquid surface of the dehydration liquid, 32.6kg of second polar solvent (N-methylpyrrolidone) is added into the dehydration liquid by a spray method; in the whole dehydration process, a small amount of the volatilized first polar solvent or second polar solvent flows back to the reaction kettle through the dehydration rectifying tower, and the top of the dehydration rectifying tower discharges water vapor.
When the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is detected to be about 1.2, stopping dehydration to obtain the residual dehydration liquid, wherein the filling degree of the reaction kettle is 84.9%, and the whole dehydration time is 2.0h. Calculated, 30.7kg of the solution was removed, wherein the water content in 30.7kg of the solution was 98.88wt%, the molar ratio of water to total sulfur was 1.18, and 1.4mol of hydrogen sulfide gas was lost with dehydration.
Example 2
33.7kg (340 mo 1) of a first polar solvent (N-methylpyrrolidone), 28.0kg (200 mo 1) of an aqueous sodium hydrosulfide solution (mass fraction: 40%) and 19.6kg (206 mo 1) of an aqueous sodium hydroxide solution (mass fraction: 42%) were mixed in a reaction vessel, at which time the filling degree of the reaction vessel was 81.4%, and the reaction vessel was connected to a dehydration rectifying column; heating for 0.5h to 95 ℃ under stirring, wherein sodium sulfide in the reaction kettle is completely dissolved in a mixed solvent consisting of water and a first polar solvent, and thus a dehydration liquid system is obtained.
Then, the dehydration liquid is dehydrated by reducing the pressure and maintaining the pressure in the reaction kettle to be 30kPa, wherein the reducing rate is 1.8kPa/min, and the temperature is increased to 140 ℃ under the pressure, and the heating rate is 0.8 ℃/min; in the process, when foam appears on the liquid surface of the dehydration liquid, 35.4kg of second polar solvent (N-methylpyrrolidone) is added into the dehydration liquid by a spray method; in the whole dehydration process, a small amount of the volatilized first polar solvent or second polar solvent flows back to the reaction kettle through the dehydration rectifying tower, and the top of the dehydration rectifying tower discharges water vapor.
When the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is detected to be about 1.2, stopping dehydration to obtain the residual dehydration liquid, wherein the filling degree of the reaction kettle is 86.0%, and the whole dehydration time is 2.1h. Calculated, a total of 30.9kg of the solution was removed, wherein the water content in the 30.9kg of the solution was 98.32wt%, the molar ratio of water to total sulfur was 1.25, and 1.5mol of hydrogen sulfide gas was lost with dehydration.
Example 3
28.3kg (323 mo 1) of a first polar solvent (N-methylpyrrolidone), 28.3kg (202 mo 1) of an aqueous sodium hydrosulfide solution (mass fraction: 40%) and 19.6kg (206 mo 1) of an aqueous sodium hydroxide solution (mass fraction: 42%) were mixed in a reaction vessel, at which time the filling degree of the reaction vessel was 80.0%, and the reaction vessel was connected to a dehydration rectifying column; heating for 0.6h to 110 ℃ under stirring, wherein sodium sulfide in the reaction kettle is completely dissolved in a mixed solvent consisting of water and a first polar solvent, and thus a dehydration liquid system is obtained.
Then, the dehydration liquid is dehydrated by reducing the pressure and maintaining the pressure in the reaction kettle to be 50kPa, wherein the reducing rate is 2.4kPa/min, and the temperature is increased to 160 ℃ under the pressure, and the heating rate is 1.0 ℃/min; in the process, 31.2kg of a second polar solvent (N-methylpyrrolidone) is added into the dehydration liquid by a spray method when the liquid surface of the dehydration liquid has foam; in the whole dehydration process, a small amount of the volatilized first polar solvent or second polar solvent flows back to the reaction kettle through the dehydration rectifying tower, and the top of the dehydration rectifying tower discharges water vapor.
When the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is detected to be about 1.2, stopping dehydration to obtain the residual dehydration liquid, wherein the filling degree of the reaction kettle is 80.1%, and the whole dehydration time is 1.9h. Calculated, 31.1kg of the solution was removed altogether, wherein the water content in 31.1kg of the solution was 99.22wt% and the molar ratio of water to total sulfur was 1.14, losing 1.3mol of hydrogen sulfide gas with dehydration.
Example 4
Example 4 differs from example 1 only in that the first polar solvent is N-methylpyrrolidone, the second polar solvent is tetramethylurea, and the remaining conditions are the same.
After the dehydration in this example was completed, the filling degree of the reaction vessel was 84.5%, and the entire dehydration time was 2.5 hours. Calculated, 31.1kg of the solution was removed altogether, wherein the water content in 31.1kg of the solution was 96.8wt% and the molar ratio of water to total sulfur was 1.25, losing 1.6mol of hydrogen sulfide gas with dehydration.
Example 5
Example 5 differs from example 1 only in that the second polar solvent (N-methylpyrrolidone) was directly added to the dehydrated liquid system by a pump, and the other conditions were the same.
After the dehydration in this example was completed, the filling degree of the reaction vessel was 84.1%, and the entire dehydration time was 2.7 hours. Calculated, 31.5kg of the solution was removed altogether, wherein the water content in 31.5kg of the solution was 97.2wt%, the molar ratio of water to total sulfur was 1.1, and 2.4mol of hydrogen sulfide gas was lost with dehydration.
Example 6
Example 6 differs from example 1 only in that both the first polar solvent and the second polar solvent are hexamethylphosphoric triamide, and the remaining conditions are the same.
After the dehydration in this example was completed, the filling degree of the reaction vessel was 82.3%, and the entire dehydration time was 2.4 hours. Calculated, a total of 30.5kg of the solution was removed, wherein the water content in the 30.5kg of the solution was 98.9wt%, the molar ratio of water to total sulfur was 1.24, and 1.6mol of hydrogen sulfide gas was lost with dehydration.
Comparative example 1
Comparative example 1 is different from example 1 only in that the mass of the first polar solvent (N-methylpyrrolidone) is 35.7kg (360 mo 1), and the mass of the second polar solvent (N-methylpyrrolidone) is zero, that is, the second polar solvent (N-methylpyrrolidone) is not added, and the other conditions are the same.
In the comparative example, the dehydration is carried out by heating to 180 ℃ for 3.6 hours, so that the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 51.6% after the dehydration is finished. Meanwhile, 31.4kg of the solution was removed by co-dehydration, wherein the water content in 31.4kg of the solution was 96.4wt%, the molar ratio of water to total sulfur was 1.23, and 4.5mol of hydrogen sulfide gas was lost with dehydration.
Comparative example 2
27.3kg (275.6mo1) of a first polar solvent (N-methylpyrrolidone), 21.4kg (152.7 mol) of an aqueous sodium hydrosulfide solution (mass fraction: 40%) and 14.7kg (154.3 mol) of an aqueous sodium hydroxide solution (mass fraction: 42%) were mixed in a reaction vessel, at which time the filling degree of the reaction vessel was 63.4%, and the reaction vessel was connected to a dehydration rectifying column; heating for 0.5h to 95 ℃ under the stirring state, wherein sodium sulfide in the reaction kettle is completely dissolved in a mixed solvent consisting of water and a first polar solvent, namely, a dehydration liquid system is obtained; wherein 19.6kg of a second polar solvent (N-methylpyrrolidone) was added to the dehydrated liquid by spraying during heating for 0.5h to 95 ℃.
Then, the dehydration liquid system is dehydrated by reducing the pressure and maintaining the pressure in the reaction kettle to be 40kPa, wherein the reducing rate is 2.0kPa/min, and the temperature is increased to 150 ℃ under the pressure, and the heating rate is 0.9 ℃/min; in the whole dehydration process, a small amount of the volatilized first polar solvent or second polar solvent flows back to the reaction kettle through the dehydration rectifying tower, and the top of the dehydration rectifying tower discharges water vapor.
In the comparative example, the dehydration is carried out by heating to 175 ℃ and the whole dehydration time is 3.4 hours, so that the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 63.4% after the dehydration is finished. Meanwhile, 24.4kg of the solution was removed by co-dehydration, in which the content of water in 24.4kg of the solution was 97.8wt%, the molar ratio of water to total sulfur was 1.20, and 1.8mol of hydrogen sulfide gas was lost with dehydration.
Comparative example 3
Comparative example 3 was different from example 1 only in that 7.1kg (71.7 mo 1) of the second polar solvent was added in the course of heating to 95℃for 0.5h under stirring, and in this case, the degree of filling of the reaction vessel was 90%, and the other conditions were the same.
In the comparative example, the dehydration is carried out by heating to 178 ℃, the whole dehydration time is 3.6 hours, the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 59.5% after the dehydration is finished. Meanwhile, 30.6kg of the solution was removed by co-dehydration, wherein the water content in the 30.6kg of the solution was 98.6wt%, the molar ratio of water to total sulfur was 1.25, and 4.2mol of hydrogen sulfide gas was lost with dehydration.
Comparative example 4
Comparative example 4 was different from example 1 only in that the pressure in the reaction vessel was maintained at 20kPa by reducing the pressure, and the other conditions were the same.
In the comparative example, dehydration is carried out only by heating to 120 ℃, the whole dehydration time is 2.2 hours, the molar ratio of water to total sulfur in dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 78.5% after the dehydration is finished. Meanwhile, 31.1kg of the solution was removed by co-dehydration, wherein the content of water in the 31.1kg of the solution was 98.5wt%, the molar ratio of water to total sulfur was 1.13, and 5.2mol of hydrogen sulfide gas was lost with dehydration.
Comparative example 5
Comparative example 5 was different from example 1 only in that the pressure in the reaction vessel was maintained at 70kPa by reducing the pressure, and the other conditions were the same.
In the comparative example, the dehydration is carried out by heating to 175 ℃, the whole dehydration time is 3.2 hours, the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 85.1% after the dehydration is finished. Meanwhile, 30.87kg of the solution was removed by co-dehydration, in which the water content in 30.87kg of the solution was 99.21wt% and the molar ratio of water to total sulfur was 1.11, losing 1.3mol of hydrogen sulfide gas with dehydration.
Comparative example 6
Comparative example 6 differs from example 1 only in that the second polar solvent is water, and the other conditions are the same.
In the comparative example, the dehydration is carried out by heating to 185 ℃ for 4.7 hours, so that the molar ratio of water to total sulfur in the dehydration liquid in the reaction kettle is about 1.2, and the filling degree of the reaction kettle is 52.1% after the dehydration is finished. Meanwhile, 60.8kg of the solution was removed by co-dehydration, wherein the water content in 60.8kg of the solution was 98.5wt%, the molar ratio of water to total sulfur was 1.15, and 1.6mol of hydrogen sulfide gas was lost with dehydration.
The residual dehydration solutions obtained in examples 1 to 6 and comparative examples 1 to 6 were used as a preparation method for polyphenylene sulfide by carrying out subsequent polymerization, and the specific preparation method is as follows: putting the corresponding residual dehydration liquid into a polymerization kettle from the reaction kettle, and then adding p-dichlorobenzene into the polymerization kettle, wherein the molar ratio of the p-dichlorobenzene to the total sulfur in the residual dehydration liquid is 1.01:1; then heating to 225 ℃, then carrying out heat preservation reaction for 2 hours, and then adding water, wherein the molar ratio of the added water to the total sulfur in the residual dehydration liquid is 0.8:1, continuously heating to 260 ℃ at 0.5 ℃/min, continuously carrying out heat preservation reaction for 2 hours, and slowly cooling to 100 ℃ at 1.2 ℃/min after the reaction is finished to obtain a reactant containing polyphenylene sulfide; the obtained reactants containing the polyphenylene sulfide are filtered by a 120-mesh screen, then washed by NMP, 0.1% dilute hydrochloric acid and water in sequence, finally dried, and the corresponding polyphenylene sulfide is obtained, the yield and the thermal stability of the corresponding polyphenylene sulfide are calculated and detected, and the specific calculation results are shown in table 1.
TABLE 1
As can be seen from the data in table 1, in the dehydration method of the raw materials in the production of polyphenylene sulfide according to the present invention, the increase of the foam height caused by a large amount of bubbles can be avoided, so that the filling degree of the whole reaction apparatus is maintained at 80% -86%, and the dehydration efficiency can be improved while the volume of the reaction apparatus is fully utilized, the raw material loss is reduced, the balance of the raw material ratio is ensured, and the production efficiency and quality of polyphenylene sulfide are further improved.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. The dehydration method of the raw materials in the production of the polyphenylene sulfide is characterized by comprising the following steps:
placing sodium hydrosulfide aqueous solution, alkaline aqueous solution and first polar solvent into a reaction device to ensure that the filling degree of the reaction device is 80% -85%, then heating and raising the temperature to obtain a dehydration liquid system, and then decompressing and maintaining the pressure in the reaction device to be 30-50 kPa;
and heating and dehydrating the dehydrated liquid system, and stopping dehydrating when the dehydrated liquid system is dehydrated to a preset water content condition, wherein when the liquid level of the dehydrated liquid is foamed, a second polar solvent is added into the dehydrated liquid system, the surface tension of the second polar solvent is smaller than that of water, and the filling degree of the reaction device is controlled to be maintained at 80% -86%.
2. The method for dehydrating a raw material in polyphenylene sulfide production according to claim 1, wherein the molar ratio of the first polar solvent to the sodium hydrosulfide aqueous solution is 1.6:1 to 1.8:1;
and/or the molar ratio of the alkaline aqueous solution to the sodium hydrosulfide aqueous solution is 1.01:1-1.03:1.
3. The method for dehydrating a raw material in polyphenylene sulfide production according to claim 1, wherein the mass ratio of the first polar solvent to the second polar solvent is 0.9:1 to 1.1:1;
and/or, the difference in surface tension between the second polar solvent and the water is 30mN/m to 40mN/m.
4. The method for dehydrating a raw material for polyphenylene sulfide production according to claim 1, wherein the first polar solvent and the second polar solvent are the same.
5. The method for dehydrating a raw material for polyphenylene sulfide production according to claim 1, wherein the rate of the depressurization is 1.8kPa/min to 2.4kPa/min in the process of depressurizing and maintaining the pressure of the dehydrated liquid system at 30kPa to 50kPa.
6. The method for dehydrating raw materials in polyphenylene sulfide production according to claim 1, wherein in the step of heating and dehydrating the dehydration liquid system, the heating rate is 0.8 ℃/min to 1.1 ℃/min;
and/or, in the step of heating and dehydrating the dehydration liquid system, the dehydration temperature is 140-160 ℃.
7. The method for dehydrating raw materials in polyphenylene sulfide production according to claim 1, wherein the heating temperature is raised to 90 ℃ to 110 ℃ and the heating temperature is raised for 0.4h to 0.6h in the course of the heating temperature raising treatment.
8. The method for dehydrating a raw material in the production of polyphenylene sulfide according to claim 1, wherein the first polar solvent and the second polar solvent are both selected from an organic solvent, and the organic solvent is at least one selected from the group consisting of N-methylpyrrolidone, tetramethylurea, hexamethylphosphoric triamide;
and/or the alkaline aqueous solution is selected from aqueous sodium hydroxide solution and/or aqueous potassium hydroxide solution.
9. The method for dehydrating a raw material for polyphenylene sulfide production according to claim 1, wherein the second polar solvent is added to the dehydrated liquid system by spraying.
10. A method for producing polyphenylene sulfide, characterized in that the raw material is dehydrated by the method for dehydrating raw material in the production of polyphenylene sulfide according to any one of claims 1 to 9.
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