CN116410079A - Separation method of terephthalic acid in methyl methacrylate oxidized waste residues - Google Patents
Separation method of terephthalic acid in methyl methacrylate oxidized waste residues Download PDFInfo
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- CN116410079A CN116410079A CN202111660276.9A CN202111660276A CN116410079A CN 116410079 A CN116410079 A CN 116410079A CN 202111660276 A CN202111660276 A CN 202111660276A CN 116410079 A CN116410079 A CN 116410079A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
- C07C51/367—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by introduction of functional groups containing oxygen only in singly bound form
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
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- Y02W30/62—Plastics recycling; Rubber recycling
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Abstract
The invention discloses a separation method of terephthalic acid in methyl methacrylate oxidized waste residue, which comprises the steps of coating terephthalic acid formed by complex compounds of vanillic acid, alkyl chain modified vanillic acid and metal ions, and adopting a floatation method for floatation. The floatability of the complex coating is greatly improved, and the complex coating can be applied to not only the recovery of solid terephthalic acid, but also the treatment of terephthalic acid wastewater, thereby achieving the capture and removal of trace terephthalic acid. Compared with the traditional process, the preparation process is simple, the preparation conditions are mild, the use of an organic solvent and the generation of high-salt wastewater are avoided, and the preparation method can be widely applied to industrial production.
Description
Technical Field
The invention relates to the field of chemical waste residue recovery, in particular to a method for separating terephthalic acid from methyl methacrylate oxidized waste residue.
Background
Methyl Methacrylate (MMA) is widely applied in national defense, construction, fine chemical engineering and other aspects, is an important polymer monomer, and the Polymer (PMMA) can be used for producing organic glass, can be copolymerized with monomers such as acrylic ester, styrene and the like to produce products such as paint, ignition agent and the like, and can be further copolymerized with unsaturated polyester to produce other high polymer materials as a cross-linking agent.
At present, the MMA production process in China mainly adopts the traditional acetone cyanohydrin method (ACH method), the synthetic route is complex, the production cost is high, a large amount of waste acid solution is produced, the toxicity to the environment is large, and production is stopped for small and medium-sized enterprises. After the 70 th century, due to the rapid development of technology, a green technological route for producing MMA by a C4 method appears, isobutene/tertiary butanol is used as a raw material, methacrylic acid (MAA) is generated by two-step oxidation, and MMA is prepared by esterification, so that the raw material is easy to obtain, the process is advanced, and the production cost is low. However, during the oxidation of isobutene, a certain amount of by-products such as terephthalic acid, maleic acid, fumaric acid, etc. are formed. The by-product in the oxidation reaction gas is firstly quenched and deposited in a solid form, oxidized waste residue is obtained after filtration, and the filtration efficiency can be improved by using a filter aid before filtration. According to incomplete statistics, the annual production of waste residue by a national MMA device of C4 method is more than 5000 tons, and the main components in the waste residue are methacrylic acid (MAA), terephthalic acid (PTA), diatomite, benzoic acid, maleic Acid (MA), fumaric Acid (FA) and the like, and the content of the MAA and the PTA is high, and the proportion is more than 80 percent. Because of the technical restrictions, the current oxidation waste residue treatment mode generated by each MMA device mainly comprises the steps of periodically discharging slag, bagging and delivering to incineration treatment, but because the residues are basically high-boiling-point organic matters, the combustion efficiency is low, the environmental pollution is large, the raw material utilization rate is low, and serious resource waste is caused.
Terephthalic acid is an important raw material for synthesizing polyester, and polyester is an important raw material for manufacturing polyester fibers, coatings, films and engineering plastics, in particular to polyethylene terephthalate (PET) synthesized by terephthalic acid and Ethylene Glycol (EG), which has excellent performances such as good mechanical property, electrical insulation property, fatigue resistance, easy recovery and the like, and is increasingly replacing aluminum, glass, ceramics and other synthetic materials.
At present, terephthalic acid waste residues and wastewater are generally treated by adopting a burying method, an incineration method and a water treatment method, and because the terephthalic acid waste residues and wastewater are difficult to degrade, the burying and the incineration both pollute the environment, and the water treatment method has high cost and is difficult to industrialize. On the other hand, PTA is an important industrial raw material, and the removal of PTA as waste not only generates serious environmental hazard, but also wastes serious resources, so that new technologies for recovering PTA resources are urgently needed to be developed.
Along with the progress of technology, the solid waste treatment process for developing green new energy is a trend, and if useful components in waste residues can be recycled, the waste residue treatment capacity can be greatly reduced, and the waste residue resource utilization is realized.
Disclosure of Invention
The invention aims to provide a separation method of terephthalic acid in methyl methacrylate oxidized waste residues, which is used for recovering terephthalic acid from residues, so as to reduce waste emission, improve the utilization rate of products and realize the recycling of the residues.
A separation method of terephthalic acid in methyl methacrylate oxidized waste residues comprises the following steps:
(1) Residue pretreatment:
alcohol washing is carried out on residues in the MMA oxidation process, and residues A after treatment are obtained through filtration;
(2) Centrifugal separation
Adding the residue after alcohol washing into water for ultrasonic dispersion, then performing centrifugal separation, separating by utilizing the granularity and density difference of silicon dioxide and terephthalic acid, adding a certain amount of high-pressure water into a centrifugal machine at intervals, settling a heavy phase relatively quickly, enabling a light phase to flow out along with water flow, and recording the light phase as slurry B;
(3) Preparation of alkyl chain modified vanillic acid
Adding halogen simple substance or halogenated hydrogen into long-chain alkane organic matter, stirring for more than 60min at 30-90 ℃ to fully react to obtain halogenated long-chain organic matter; mixing a certain amount of Vanillic Acid (VA) solution and halogenated long-chain organic matters, stirring and heating at 25-60 ℃ for 30-120min to obtain alkyl chain modified vanillic acid (M-VA);
(4) Separation of terephthalic acid
Adding a metal compound solution into the slurry B, regulating the pH to 2.0-7.0, and fully stirring;
the mixture of Vanillic Acid (VA) and alkyl chain modified vanillic acid (M-VA) is added into the slurry, and is fully stirred, then air is introduced into the slurry, bubbling phenomenon is generated in the slurry, terephthalic acid moves directionally towards the bubble direction, and the terephthalic acid is taken out of a flotation machine and is marked as slurry C.
Since part of carboxyl groups on the surface of the terephthalic acid solid are dissociated, the terephthalic acid solid has a certain negative charge, and under the action of static electricity, Y n+ Will selectively adsorb to the surface of terephthalic acid solid.
VA and M-VA will adsorb Y on terephthalic acid surface n+ Complexation occurs to form a network structure coated on the surface of terephthalic acid, and the coating is amphiphilic due to the existence of a hydrophobic chain segment in M-VA, so that the floatability of terephthalic acid is improved. And (3) introducing air into the slurry, wherein bubbling phenomenon is generated in the slurry due to the existence of partial free M-VA, and terephthalic acid particles coated by the complex network can directionally move towards the bubble direction due to the existence of a hydrophobic chain segment with a certain density on the surface and are carried out of the flotation machine under the continuous bubbling action. Because the diatomite surface is hydrophilic, the diatomite cannot move along with the air bubbles in a directional way, and the particle density of the diatomite is higher than that of terephthalic acid, and finally the diatomite is left in the flotation machine, so that the diatomite and the terephthalic acid are separated efficiently.
(5) Purification of terephthalic acid:
VA, M-VA and Y n+ The complex system formed has acid sensitivity, and the slurry C of the obtained terephthalic acid is regulatedThe pH value is 2.0-6.0, the mixture is fully stirred, the complex structure is automatically decomposed, high-purity terephthalic acid can be recovered after filtration and drying, and the rest Y n+ The solution of VA and M-VA can be returned to the step (4) again for recycling.
Preferably, in the step (1), the residue of the MMA oxidation process is discharged from the MMA oxidation process filter and is conveyed to an inlet at the upper part of the alcohol washing tank through a belt, and the upper part of the belt is sealed by a plastic cover to prevent volatile gas from escaping. Adding alcohol solvent into the oxidation residue according to a certain proportion, and stirring for more than 30min at normal temperature in an alcohol washing tank. After the soluble substances are sufficiently dissolved, the solid-liquid mixture is centrifugally filtered, residues which do not contain MAA, FA, MA and the like are collected, and the filtrate is returned to the device for recycling.
Preferably, the main components of the residue of MMA oxidation step in the step (1) are 10-25% methacrylic acid, 40-70% terephthalic acid, 2-20% water, 0.5-5% diatomite, 2-9% maleic acid, 0.1-1% fumaric acid and less than 0.5% polymerization inhibitor.
Preferably, the alcohol used in the alcohol washing in the step (1) is one or more selected from methanol, ethanol, n-propanol, isopropanol and the like, and the mass ratio of the alcohol to the residue is 5:1 to 50:1, preferably 10: 1-20: 1, the stirring time is controlled to be 30-120min, and the rotating speed is controlled to be 50-300 rpm/min.
The main components of the filtrate are alcohol solvents, MAA, MA, FA and the like, and the main components of the filter residue are terephthalic acid, diatomite and the like.
Preferably, in the ultrasonic dispersion in the step (2), the mass ratio of the alcohol washing residue to the water is 1:1 to 1:20, preferably 1:1 to 1:5, the ultrasonic dispersion time is 30-120 min. The centrifugal speed is controlled to be 200-500 r/min, the high-pressure water quantity is fed to be 120-200L each time, the feeding is carried out once at intervals of 10-15 s, and the total feeding is 1-5 times.
Preferably, the long-chain alkane organic matter in the step (3) is one or more of C8-C16 alkane and C9-C13 aldehyde, preferably nonane, decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane or decanal, n-undecane, n-dodecanal and tridecanol.
Halogen simple substance or halogen hydrogen is preferably Cl 2 、Br 2 、I 2 One or more of HCl, HBr or HI and the like, and when the added substance is gas, air can be used for dilution, wherein the mass concentration of the halogen simple substance or the halogenated hydrogen is 1-5%.
Preferably, the addition molar quantity of the halogen simple substance or the halogenated hydrogen is 0.02-1 times of the molar quantity of the halogenated long-chain alkane organic matters.
Preferably, in the step (3), the concentration of the vanilloid solution is 5-20%.
The preferable mole ratio of the vanillic acid to the long-chain alkane organic matters is 1:1 to 1:10.
preferably, the metal compound in step (4) is a metal ion Fe 3+ 、Cr 3+ 、Cu 2+ 、Zn 2+ 、Zr 4+ One or more of the compounds of (2), preferably Fe 3+ 、Cu 2+ A compound, wherein the addition amount of the metal compound in the metal compound solution is 0.02% -0.5% of the mass of the initial residue of the treatment, preferably the metal compound comprises FeCl 3 ，CrCl 3 ，CuCl 2 、ZnCl 2 、ZrCl 2 One or more of the following.
Preferably, in the step (4), the mass ratio of the Vanillic Acid (VA) to the alkyl chain modified vanillic acid (M-VA) is 1:5 to 1:20.
preferably, in the step (5), the drying time is 60-400 min, and the drying temperature is 120-300 ℃. Preferably, the drying time is 100-150 min, and the drying temperature is 140-200 ℃.
The purity of the PTA product obtained by filtering and drying is up to more than 99 percent, and the purity can reach the standard of sale.
Preferably, in the present invention, the synthetic reaction route of M-VA is as follows:
VA, M-VA and Y n+ The complex network formed is schematically shown below:
compared with the prior art, the invention has the following implementation effects:
(1) The invention synthesizes a complex with adjustable hydrophobicity, can realize the selective coating of terephthalic acid solid particles, and after being modified, the vanillic acid and metal ions are complexed to form strong intermolecular force with terephthalic acid, thereby greatly improving the flotation efficiency, being applicable to the recovery of terephthalic acid solid, being applicable to the capture of trace terephthalic acid in wastewater, and finally reaching the purity of PTA (pure terephthalic acid) of more than 99 percent after drying to reach the selling standard.
(2) The process route is simple, the energy consumption is low, the environment is protected, and the complete separation of MAA, PTA and diatomite is realized by adopting an alcohol washing-primary centrifugation-secondary flotation separation technology.
(3) Compared with the traditional terephthalic acid recovery technology, the method avoids the use of organic solvents and high-concentration acid and alkali, has mild process conditions and high separation efficiency, can recycle raw materials, greatly reduces the discharge of salt-containing wastewater, and is a more green, environment-friendly and sustainable process.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent in light of the examples of the present invention, which are set forth more fully in the claims below. All other embodiments, based on the examples herein, which are within the scope of the invention as defined by the claims, will be within the scope of the invention as defined by the claims.
The raw material sources are as follows: the main components of the methyl methacrylate oxidation process residues are 15% methacrylic acid, 60% terephthalic acid, 10% water, 5% diatomite, 9% maleic acid, 0.2% fumaric acid, less than 0.5% polymerization inhibitor and the like.
Example 1
(1) Residue pretreatment: 100kg of oxidized residues are conveyed to an inlet of an alcohol washing tank through a conveyor belt, and the mass ratio of the mixed methanol to the residues is 5:1, stirring and dissolving for 30min at normal temperature, centrifugally filtering the solid-liquid mixture at the rotating speed of 200rpm/min, returning filtrate to the device for recycling, and enabling the filter cake A to enter the next process treatment step.
(2) And (3) centrifugal separation: aiming at the filter cake A in the step (1), 100kg of deionized water is added to prepare 50% slurry, the slurry is conveyed to a centrifugal separator through a screw feeding device after ultrasonic dispersion, the rotating speed is controlled to be 500r/min, the high-pressure water quantity is added to the centrifugal separator for 120L, the water is added every 10s, the total water is added for 5 times, and the light phase (recorded as slurry B) flowing out of the centrifugal separator enters the next step.
(3) Alkyl chain modified vanillic acid preparation: continuous Cl introduction into 1kg of n-dodecane 2 And air mixture, wherein Cl 2 The mass concentration is 1%, the charging time is 50min, the charging amount is 120L/min (actual Cl) 2 And the molar ratio of the long-chain organic matters is 1:50 Stirring at 60 ℃ for 60min to fully react; 10kg of 10wt% vanilla acid solution, namely 1:1, stirring for 30min at room temperature to obtain alkyl chain modified vanillic acid (M-VA);
(4) Separation of terephthalic acid: adding 10% FeCl to slurry B 3 2kg of solution, adjusting the pH to 6.0, adding 170g of 10wt% vanilla acid solution and 830g of alkyl chain modified vanilla acid solution with the same concentration, fully stirring, introducing air into the slurry at a flow rate of 120L/h, and taking the terephthalic acid (slurry C) out of the flotation machine by bubbles after a period of time.
(5) Purification of terephthalic acid:
and (3) regulating the pH value of the slurry of the terephthalic acid obtained in the step (4) to 3.0, fully stirring, filtering, and drying at 120 ℃ for 60min to obtain the high-purity terephthalic acid with the purity of 99.3%.
Examples 2 to 11
100kg of methyl methacrylate oxidized residue was prepared as in example 1 and fed to the inlet of the alcohol washing tank by a conveyor belt, wherein,
in the step (1), the residue was first pretreated, and the pretreatment conditions were changed to obtain the treated residues A1 to a11 as shown in table 1.
In the step (2), the centrifugal separation conditions were changed to obtain slurries B1 to B11, as shown in table 2.
In the step (3), the preparation conditions for the alkyl chain modified vanillic acid are shown in table 3.
In the step (4), the preparation process of the tunable complexes C1 to C11 in the separation of terephthalic acid is shown in Table 4.
In the step (5), the terephthalic acid purification process, namely the final terephthalic acid products P1 to P11, were obtained, and the preparation conditions thereof are shown in Table 5.
TABLE 1 residue pretreatment conditions
Table 2 centrifugal separation conditions to obtain slurries B1 to B11
TABLE 3 preparation conditions for the preparation of alkyl chain modified vanillic acid
TABLE 4 preparation of tunable complexes C1-C11 in terephthalic acid separations
TABLE 5 purification of terephthalic acid to obtain final terephthalic acid products P1-P11
| Slurry C | Purification of PH | Drying temperature/. Degree.C | Drying time/min | Terephthalic acid purity% | |
| Example 1 | C1 | 6 | 120 | 120 | 99.3 |
| Example 2 | C2 | 6 | 150 | 300 | 99.5 |
| Example 3 | C3 | 6 | 120 | 400 | 99.6 |
| Example 4 | C4 | 4 | 200 | 240 | 99.3 |
| Example 5 | C5 | 4 | 250 | 60 | 98.7 |
| Example 6 | C6 | 2 | 300 | 60 | 98.9 |
| Example 7 | C7 | 2 | 120 | 300 | 97.3 |
| Example 8 | C8 | 2 | 240 | 180 | 97.3 |
| Example 9 | C9 | 6 | 240 | 210 | 99.8 |
| Example 10 | C10 | 6 | 150 | 300 | 99.1 |
| Example 11 | C11 | 4 | 300 | 210 | 98.1 |
Claims (8)
1. The method for separating terephthalic acid from methyl methacrylate oxidized waste residues is characterized by comprising the following steps:
(1) Residue pretreatment:
alcohol washing is carried out on residues in the MMA oxidation process, and residues A after treatment are obtained through filtration;
(2) Centrifugal separation
Adding the residue after alcohol washing into water for ultrasonic dispersion, then performing centrifugal separation, adding a certain amount of high-pressure water into the centrifugal machine at intervals, settling a heavy phase relatively quickly, enabling a light phase to flow out along with water flow, and marking the light phase as slurry B;
(3) Preparation of alkyl chain modified vanillic acid
Adding halogen simple substance or halogenated hydrogen into long-chain alkane organic matter, stirring for more than 60min at 30-90 ℃ to fully react to obtain halogenated long-chain organic matter; mixing a certain amount of vanilloid solution and halogenated long-chain organic matter, stirring and heating at 25-60deg.C for 30-120min to obtain alkyl chain modified vanillic acid;
(4) Separation of terephthalic acid
Adding a metal compound solution into the slurry B, regulating the pH to 2.0-7.0, and fully stirring;
adding a mixture of vanillic acid and alkyl chain modified vanillic acid into the slurry, fully stirring, forming a complex by the vanillic acid, the alkyl chain modified vanillic acid and metal ions, then introducing air into the slurry, generating a bubbling phenomenon in the slurry, enabling terephthalic acid to move directionally towards the bubble direction, and taking the terephthalic acid out of a flotation machine to be marked as slurry C;
(5) Purification of terephthalic acid:
and (3) regulating the pH value of the obtained terephthalic acid slurry C to 2.0-6.0, fully stirring, automatically decomposing a complexing structure of the terephthalic acid slurry C, filtering and drying to recover high-purity terephthalic acid, and returning the residual solution of vanillic acid, alkyl chain modified vanillic acid and metal ions to the step (4) for recycling.
2. The separation method according to claim 1, wherein in the step (1), MMA oxidation step residues are discharged from the MMA oxidation step filter and conveyed to an inlet at the upper part of the alcohol washing tank through a belt, and the upper part of the belt is sealed by a plastic cover to prevent volatile gases from escaping;
preferably, the main components of the residue of MMA oxidation step in the step (1) are 10-25% of methacrylic acid, 40-70% of terephthalic acid, 2-20% of water, 0.5-5% of diatomite, 2-9% of maleic acid, 0.1-1% of fumaric acid and less than 0.5% of polymerization inhibitor;
preferably, the alcohol used in the alcohol washing in the step (1) is one or more selected from methanol, ethanol, n-propanol and isopropanol, and the mass ratio of the alcohol to the residue is 5:1 to 50:1, preferably 10: 1-20: 1, the stirring time is controlled to be 30-120min, and the rotating speed is controlled to be 50-300 rpm/min.
3. The separation method according to claim 1, wherein the mass ratio of the alcohol washing residue to the water in the ultrasonic dispersion in the step (2) is 1:1 to 1:20, preferably 1:1 to 1:5, ultrasonic dispersion time is 30-120 min;
preferably, in the step (2), the centrifugal rotation speed is controlled to be 200-500 r/min, the high-pressure water quantity is fed to be 120-200L each time, the feeding is carried out once at intervals of 10-15 s, and the total feeding is 1-5 times.
4. A separation process according to any one of claims 1 to 3, wherein the long-chain alkane-like organic matter of step (3) is one or more of a C8-C16 alkane, a C9-C13 aldehyde, preferably nonane, decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane or decanal, n-undecane, n-dodecanal, tridecanal.
5. The process according to any one of claims 1 to 4, wherein the elemental halogen or the halogenated hydrogen is preferably Cl 2 、Br 2 、I 2 One or more of HCl, HBr, or HI;
preferably, the addition molar quantity of the halogen simple substance or the halogenated hydrogen is 0.02 to 1 time of the molar quantity of the halogenated long-chain organic matter;
preferably, the molar ratio of the vanillic acid to the long-chain alkane organic compound is 1:1 to 1:10.
6. the method according to any one of claims 1 to 5, wherein the metal compound in the step (4) is a metal ion Fe 3+ 、Cr 3+ 、Cu 2+ 、Zn 2+ 、Zr 4+ One or more of the compounds of (2), preferably Fe 3+ 、Cu 2+ A compound;
preferably, the addition amount of the metal compound in the metal compound solution is 0.02-0.5% of the mass of the initial residue after treatment;
preferably, the metal compound comprises FeCl 3 ，CrCl 3 ，CuCl 2 、ZnCl 2 、ZrCl 2 One or more of the following.
7. The method according to any one of claims 1 to 6, wherein in the step (4), the mass ratio of the Vanillic Acid (VA) to the alkyl chain modified vanillic acid (M-VA) is 1:5 to 1:20.
8. the separation method according to any one of claims 1 to 7, wherein in step (5), the drying time is 60 to 400min and the drying temperature is 120 to 300 ℃;
preferably, the drying time is 100-150 min, and the drying temperature is 140-200 ℃.
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