Method for synthesizing phenolic resin and extracting para-phenol through acid method

Abstract

The invention relates to the technical field of organic synthesis and separation, particularly discloses a method for synthesizing phenolic resin and extracting para-phenol by an acid process, and solves the problem that common commercial mixed phenol cannot be directly used for synthesizing high-quality phenolic resin and cannot be used for extracting para-phenol by two steps of phenolic resin synthesis, para-phenol crude separation and para-phenol refining. The application of the phenolic resin in chemical products is limited; the production cost of synthesizing phenolic resin from phenol is high; and the economic benefit needs to be improved. And meanwhile, high-quality phenol and o-cresol can be produced while the coalified phenol and the mixed phenol which are low in price are used for replacing petrochemical phenol to produce the phenolic resin, so that the method has certain economic benefits.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis and separation technology, specifically to a method for synthesizing phenolic resins using an acid process and extracting para-phenols. Background Technology

[0002] Phenolic resin is synthesized by incorporating mixed phenols into formaldehyde. Utilizing the difference in reactivity between phenol and o-cresol in the mixed phenols with formaldehyde, phenol reacts faster with formaldehyde during resin synthesis, while o-cresol reacts slower. Therefore, after consuming approximately 90% of the phenol, only 10-20% of the o-cresol reacts, leaving a significant amount unreacted. Thus, during the synthesis of phenolic resin using mixed phenols, free phenol and water are distilled off, and the mixture is allowed to separate into layers, yielding an oil layer of phenol and o-cresol. Further distillation of this oil layer yields 99% phenol and 99% o-cresol. Alternatively, directly using mixed phenols instead of phenol in the reaction with formaldehyde also produces phenolic resin and o-cresol products. Since mixed phenols are cheaper than phenol, while o-cresol is more expensive, using mixed phenols to partially or completely replace phenol in phenolic resin production offers certain economic benefits.

[0003] However, this approach faces significant technical obstacles: conventional coal-based mixed phenols have complex compositions, containing a considerable number of phenols with a functionality of 1, such as 2,6-xylenol and 2,4-xylenol, which react with formaldehyde. These "monofunctional" phenols cannot effectively crosslink during polymerization, terminating resin chain growth and severely degrading the mechanical properties, heat resistance, and curing characteristics of the final phenolic resin, making it difficult to meet application requirements. Therefore, ordinary commercially available mixed phenols cannot be directly used to synthesize high-quality phenolic resins, limiting their application in chemical products and hindering the high-value utilization of crude phenol resources byproducts of coal chemical industry.

[0004] On the other hand, research has found that the reactivity of different substituted phenols with formaldehyde varies by orders of magnitude. For example, the reactivity of meta-substituted phenols is much higher than that of their para-isomers. If this reactivity difference can be utilized to selectively involve the highly reactive component in the polymerization process during resin synthesis, while allowing the low-reactivity, high-value para-phenols to remain in the unreacted product, it is possible to obtain qualified resin while simultaneously enriching and extracting these high-value products, achieving a "two birds with one stone" economic benefit. However, realizing this technological concept requires that the mixed phenol raw materials used must be pre-purified, controlling the content of monofunctional phenols to an extremely low level to ensure resin quality. Simultaneously, the polymerization process needs to be precisely controlled, terminating the reaction at the appropriate time to achieve efficient separation of the active and inactive components. Therefore, developing an integrated method that is compatible with mixed phenol raw materials of specific specifications and can simultaneously produce phenolic resin and extract high-purity para-phenols through precise process control is of great significance for expanding the downstream applications of coal-based phenols, improving the economic benefits of the phenolic resin industry, and promoting the comprehensive utilization of resources. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing phenolic resin by acid method and extracting para-phenol, which solves the following technical problems: (1) ordinary commercial mixed phenols cannot be directly used to synthesize high-quality phenolic resin, which limits their application in chemical products; (2) the production cost of phenol-to-phenolic resin is high and the economic benefits need to be improved.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for synthesizing phenolic resin by acid synthesis and simultaneously extracting p-phenol includes the following steps:

[0008] (1) Phenolic resin synthesis and crude separation of para-phenol: Using acid as a catalyst, a mixed phenol containing a first component and a second component is selectively polymerized with aldehydes; the first component is phenol or a mixed phenol composed of phenol and o-cresol; the second component is at least one of m-p-cresol, m-p-ethylphenol, and m-p-isopropylphenol; by controlling the reaction depth, the meta-phenol in the second component is basically completely reacted, while the para-phenol in the first component and the second component is partially residual; after the reaction, the distillate containing unreacted phenol is separated by distillation, and the distillate is extracted to obtain an oil phase mixture rich in phenol and at least one of p-cresol, p-ethylphenol, and p-isopropylphenol;

[0009] (2) Refining of para-phenol: The oil phase mixture obtained in step (1) is subjected to distillation to separate phenol and at least one of para-cresol, para-ethylphenol and para-isopropylphenol.

[0010] The above technical solution utilizes the difference in reactivity between m-cresol and p-cresol, o-cresol, and o-ethylphenol with formaldehyde. Partially, m-p-cresol can replace phenol in the production of phenolic resins or photoresist resins (mainly used in electronic circuit boards, G-line and I-line photoresists). Unreacted phenol, p-cresol, o-cresol, and o-ethylphenol can be distilled to extract high-purity phenol, o-cresol, p-cresol, or a mixture of p-cresol and o-cresol. Since o-cresol and p-cresol are significantly more expensive than m-p-cresol, this improves economic efficiency and greatly expands the application range of mixed m-p-cresol. Simultaneously, it utilizes 3,5- The difference between xylenol and m-ethylphenol, which have high reactivity with formaldehyde, and p-ethylphenol and 2,3-xylenol, which have low reactivity with formaldehyde, allows for the use of some inexpensive m-p-ethylphenol to replace phenol in the production of phenolic resins or phenolic resins for photoresists (mainly used in electronic circuit boards, G-line and I-line photoresists). Unreacted phenol, p-ethylphenol, and 2,3-xylenol can be distilled to extract high-purity phenol, p-ethylphenol, or a mixture of p-ethylphenol / 2,3-xylenol. Since p-ethylphenol is significantly more expensive than m-p-ethylphenol, this further improves economic efficiency and expands the application range of mixed m-p-ethylphenol.

[0011] Further, the feature is that, in step (1), the mass ratio of the first component to the second component is 20:80 to 100:0.

[0012] Further, the first component is characterized in that, when it is phenol, the phenol content is ≥90%, o-cresol is ≤10%, and 2,6-xylenol is ≤0.5%; when it is a mixed phenol, it is composed of 50-90% phenol and 10-50% o-cresol by mass, and 2,6-xylenol is ≤0.5%.

[0013] Further, the second component is characterized by satisfying one of the following conditions:

[0014] a. When it is m-p-cresol, the total content of m-cresol, p-cresol, and o-ethylphenol is ≥98%, o-ethylphenol is ≤12%, o-cresol is ≤1%, 2,6-xylenol is ≤2%, and 2,4- / 2,5-xylenol is ≤1%;

[0015] b. When it is m- or p-ethylphenol, the total content of 2,3-xylenol, m-ethylphenol, p-ethylphenol and 3,5-xylenol is ≥98%, 3,5-xylenol is ≤10%, 2,4- / 2,5-methylethylphenol is ≤1%, 2,4- / 2,5-xylenol is ≤1%, and 2,4,6-trimethylphenol is ≤1%;

[0016] c. When the substance is m- or p-isopropylphenol, the total content of 2,3-methylethylphenol, m-isopropylphenol, m- or p-propylphenol and 3-ethyl-5-methylphenol is ≥90%, 3,4-xylenol is ≤5%, 2,3,5-trimethylphenol is ≤5%, 2,4- / 2,5-methylethylphenol is ≤1%, 2,4,5-trimethylphenol is ≤1%, 2,4,6-trimethylphenol is ≤1%, and 2,3,6-trimethylphenol is ≤1%.

[0017] Further, the catalyst in step (1) is selected from one or more of oxalic acid, formic acid, phosphoric acid, hydrochloric acid, aminosulfonic acid, and benzenesulfonic acid, and its addition amount is 0.1 to 5% of the total mass of the mixed phenols.

[0018] Further, the feature is that, in step (1), the aldehyde is an aqueous formaldehyde solution or paraformaldehyde; the total molar ratio of the aldehyde to the phenols having two or more reactive sites in the mixed phenols is 0.5:1 to 1.5:1.

[0019] Further, the characteristic is that, in step (1), the solvent used for extraction is toluene or methyl isobutyl ether, and the amount used is 0.5 to 2 times the total mass of the raw material phenolic substances.

[0020] Further, the characteristic is that, in step (1), the control of the reaction depth is achieved by the following method: the reaction is carried out at 80 to 100°C, and when the sample analysis shows that the content of m-cresol, m-ethylphenol and / or m-isopropylphenol is ≤1% and the phenol content is 5 to 20%, the reaction is terminated and the distillation separation step is entered.

[0021] Further, the feature is that, in step (1), the aqueous phase rich in phenol obtained from the distillate is supplemented with an acid catalyst accounting for 0.01 to 0.1% of the total mass of the mixed phenols, and after being refluxed at 80 to 110°C for 1 to 3 hours, it is then extracted with the solvent.

[0022] Through the above technical solution, the present invention provides a method for adding acid to the wastewater distilled during polymerization for further polymerization. This method allows unreacted free m-cresol and free phenol to react with distilled formaldehyde to generate a prepolymer, thereby removing excess formaldehyde and m-cresol. This facilitates the extraction of 99% high-quality products such as p-cresol, p-ethylphenol, and p-isopropylphenol, and is also beneficial for the treatment of phenol-containing wastewater. The prepolymer is returned to the polymerization system, which can increase resin production and reduce solid waste.

[0023] Furthermore, the feature is that, in step (2), the residue obtained after distillation is used as a prepolymer and returned to the polymerization reactor in step (1) for recycling.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention utilizes inexpensive coal-based phenol and mixed phenols to replace petrochemical phenol in the production of phenolic resins, while also producing high-quality phenol and o-cresol, thus offering certain economic benefits.

[0026] 2. This invention utilizes the high reactivity of 3-ethyl-5-cresol, 2,3,5-trimethylphenol, and m-isopropylphenol with formaldehyde, and the low reactivity of p-isopropylphenol and 2,3-methylethylphenol with formaldehyde. It uses a portion of the inexpensive m-p-isopropylphenol to replace phenol in the production of phenolic resins or phenolic resins for photoresists (mainly used in electronic circuit boards, G-line and I-line photoresists). Unreacted phenol, p-isopropylphenol, and 2,3-methylethylphenol can be distilled to extract high-purity phenol, p-isopropylphenol, or a mixture of p-isopropylphenol and 2,3-methylethylphenol. The p-isopropylphenol / 2,3-methylethylphenol mixture can be separated to obtain p-isopropylphenol and 2,3-methylethylphenol. Since p-isopropylphenol is significantly more expensive than m-p-isopropylphenol, this invention also has good economic benefits and expands the application range and market demand for mixed m-p-isopropylphenol.

[0027] 3. Replacing some phenol with m-p-cresol, m-p-ethylphenol, and m-p-isopropylphenol in the production of phenolic resins can effectively solve the market problem of m-p-cresol, m-p-ethylphenol (mixed xylenol), and m-p-isopropylphenol (mixed tricresol) generated from the refining of 100,000 to 200,000 tons of crude phenol produced in newly built coal gasification, coal pyrolysis, and coal liquefaction industries. This can contribute to the healthy and orderly development of the coal gasification, coal liquefaction, and coal pyrolysis industries.

[0028] 4. The present invention employs a method of double-drop addition of formaldehyde and a portion of the second component, which allows m-cresol and p-cresol to be distributed relatively evenly on the resin chain of the phenolic resin polymer chain, thus ensuring relatively stable resin performance and better product quality.

[0029] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] Step 1: Mix 1432 parts phenol and 568 parts o-cresol with 30 parts oxalic acid (dissolved in hot water) in a reactor. Start stirring and measure the pH of the reaction solution to be 2.8. Adjust the reflux and venting devices. At a liquid temperature of 26℃, open the steam valve to raise the temperature, setting the steam pressure to no more than 0.3 MPa. When the temperature reaches 90℃, add 1100 parts formaldehyde (37% by mass) over a period of 2 hours. Raise the temperature to 98℃ at a rate of 1℃ / min and maintain the reaction temperature for 4 hours. Take a sample for analysis; gel chromatography analysis shows the phenol content to be 12.1%. Open the valve of the condensation and separation system, reflux steam distillation to remove water, continuously separate the oil layer at the bottom of the separator, and return the upper water layer to the reactor. After observing that there is no obvious oily substance in the distilled condensate, raise the temperature to 120℃ to remove most of the water; add 1 part of oxalic acid to the distillate and heat to 85℃ for 2 hours, then add 1000 parts of toluene and stir for 0.5 hours to separate the layers. Wash the oil layer once with 50 parts of water, let it stand to separate the layers, the upper layer is a phenol / o-cresol toluene layer of 1644.8 parts (containing 431.6 parts of o-cresol, 208.4 parts of phenol, and 7.8 parts of oligomers), and the water layer is 872.2 parts.

[0033] Step 2: Cool the material after removing free phenol / o-cresol to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80-85℃, the time at 2.5h, and the final pressure at -0.075--0.08Mpa. Observe the water level in the receiver at the same time, specifically ensuring that the water level remains constant within 20 minutes. Collect 2104.5 parts of the recovered liquid (including 12.6 parts of phenol and 21.3 parts of o-cresol).

[0034] Step 3: Gradually increase the vacuum to -0.095 MPa for 1.5 hours, while simultaneously increasing the temperature for dehydration. When the material temperature inside the reactor reaches 210°C and no liquid distills out, maintain the temperature for 1 hour, stop dehydration, release the vacuum with nitrogen, and under nitrogen protection, release the hot material into a stainless steel pan for cooling, then crush and bag it to obtain 1408.9 parts of thermoplastic phenolic resin (softening point 103°C, free phenol 0.6%), with a color ranging from off-white to pale yellow. 363.9 parts of the recovered liquid were obtained (including 16.5 parts of phenol and 29.7 parts of o-cresol).

[0035] Step 4: Add 1644.8 parts of the phenol / o-cresol toluene solution to a stirred layering vessel, start stirring, add recovery solution 2 and recovery solution 3, stir for 0.5 hours, let stand for 1 hour, separate the layers, remove the lower layer of water, and obtain 1723.6 parts of the upper layer toluene solution (containing 481.9 parts of o-cresol, 237.3 parts of phenol, and 7.8 parts of oligomers).

[0036] Step 5: Add 1723.6 parts of the phenol / o-cresol toluene solution to a distillation vessel with 10 trays. Heat the vessel to atmospheric pressure and then reduce the pressure to remove 1033.8 parts of toluene (including 28.1 parts of phenol and 18.6 parts of o-cresol). Then transfer the remaining material in the vessel to a high-efficiency distillation column (180 theoretical trays) and distill under reduced pressure (-0.085 MPa, reflux ratio 15) to obtain 215.2 parts of 99.7% phenol and 423.6 parts of 99.8% o-cresol. Return the 8.9 parts of residue (including 7.8 parts of prepolymer) to the polymerization reactor in the first step to synthesize the next batch of phenolic resin together with other phenolic substances.

[0037] Example 2

[0038] Step 1: In the reactor, start stirring and sequentially add 2000 parts of molten 99.2% coal-derived phenol, 1000 parts of m- / p-cresol (containing 359 parts of p-cresol, 639 parts of m-cresol, and 2 parts of o-ethylphenol), 36 parts of oxalic acid (50 parts dissolved in hot water), and 9 parts of formic acid. After feeding, measure the pH of the reaction solution to be 2.9. Adjust the reflux and venting devices, open the steam valve to raise the temperature, ensuring the steam pressure does not exceed 0.3 MPa. While maintaining the reactor temperature at 90℃, gradually add 1760 parts of 37% formaldehyde (the amount of formaldehyde is 0.8 times the total molar mass of phenol and m-cresol) over 3 hours. After adding, slowly raise the temperature at a rate of 1.0℃ / min until it reaches 98℃. Hold the temperature for 3 hours and then take a sample for analysis. Analyze the liquid chromatography. Spectroscopic analysis showed that m-cresol (0.02%) and phenol (18.5%) were within acceptable limits. The condenser and separatory system valve was opened, and steam distillation was used to remove water. The oil layer at the bottom of the separator was continuously separated, and the upper water layer was returned to the reactor. After observing that there were no obvious oily substances in the distilled condensate, the temperature was raised to 130℃ to remove most of the water. 1.5 parts of oxalic acid were added to the distillate, and the mixture was heated to 95℃ and reacted for 1.5 hours. Then, 2000 parts of toluene were added and stirred for 30 minutes, resulting in layer separation. The oil layer was washed once with 50 parts of water, and the mixture was allowed to stand and separate. The upper layer consisted of 2760.8 parts of phenol / p-cresol toluene (containing 481.7 parts of phenol, 276.2 parts of p-cresol, 1.3 parts of o-ethylphenol, 0.5 parts of m-cresol, and 10.1 parts of oligomers), and the water layer consisted of 1415.7 parts.

[0039] Step 2: Cool the material after removing free phenol / p-cresol to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80~85℃, the time at 2.5h, and the final pressure at -0.075~-0.08Mpa. Observe the water level in the receiver at the same time, specifically ensuring that the water level remains constant within 20 minutes. Collect 2148.6 parts of the recovered liquid (including: 29.2 parts of phenol, 18.2 parts of p-cresol, and 0.3 parts of other phenols).

[0040] Step 3: Gradually increase the vacuum to -0.095 MPa for 1.5 hours, while simultaneously increasing the temperature for dehydration. When the material temperature in the reactor reaches 200°C and no liquid distills out, maintain the temperature for 1 hour, stop dehydration, release the vacuum with nitrogen, and under nitrogen protection, discharge the hot material into a stainless steel pan for cooling, then crush and bag it to obtain 2387.1 parts of phenolic resin (softening point 107°C, free phenol 0.7%), with a color ranging from off-white to pale yellow. 393.8 parts of the recovered liquid were obtained (including 35.3 parts of phenol, 19.7 parts of p-cresol, and 0.2 parts of other phenols).

[0041] Step 4: Add 2760.8 parts of the phenol / o-cresol toluene solution to a stirred layering vessel, start stirring, add recovery solution 2 and recovery solution 3, stir for 0.5 hours, let stand for 1 hour, separate the layers, remove the lower layer of water, and obtain 2859.2 parts of the upper layer toluene solution to be recovered (containing 312.8 parts of p-cresol, 544 parts of phenol, 1.5 parts of o-ethylphenol, 0.6 parts of m-cresol, and 10.1 parts of oligomer).

[0042] Step 5: 2859.2 parts of phenol / p-cresol toluene solution were added to a distillation vessel with 30 trays. The temperature was raised first to atmospheric pressure and then to reduce pressure to remove 1997 parts of toluene (including 19.7 parts of phenol, 3.1 parts of p-cresol, and 0.2 parts of other phenols). The remaining material in the vessel was then transferred to a high-efficiency distillation column (180 theoretical trays) and subjected to reduced pressure distillation (-0.085 MPa, reflux ratio 10) to obtain 518.8 parts of 99.8% phenol and 289.6 parts of 99.3% p-cresol. The remaining 11.2 parts of the vessel residue (including 10.1 parts of prepolymer) were returned to the polymerization reactor in the first step to be used with other phenolic substances for the next batch of phenolic resin synthesis.

[0043] Example 3

[0044] Step 1: In the reactor, turn on the stirrer and add 2000 parts of molten coal petrochemical 99.9% phenol, 1200 parts of m- and p-ethylphenol (containing 495 parts of p-ethylphenol, 533 parts of m-ethylphenol, 116 parts of 2,3-xylenol, 48 parts of 3,5-xylenol, 5 parts of 2,4 / 2,5-xylenol, and 3 parts of 2,4 / 2,5-methylethylphenol), 32 parts of oxalic acid (50 parts dissolved in hot water), and 6 parts of 85% phosphoric acid. After feeding is complete, use pH test paper. The pH of the reaction solution was determined to be 3.0. The reflux and venting devices were adjusted, and the steam valve was opened to raise the temperature. The steam pressure should not exceed 0.3 MPa. At a reactor temperature of 95°C, 1800 parts of 37% formaldehyde (the amount of formaldehyde is 0.85 times the total molar mass of phenol, m-ethylphenol, and 3,5-xylenol) were gradually added over 2.5 hours. After addition, the temperature was raised slowly, strictly controlling the heating rate within 1.5°C / min to avoid excessive heating. The reaction was then maintained at a constant temperature of 9°C. The temperature was maintained between 5 and 100℃, then stabilized at 98℃ for 2 hours before sampling and analysis. Liquid chromatography analysis showed 0.01% m-ethylphenol and 11.3% phenol, which met the acceptable standards. The condenser and separatory system valve was opened, and refluxed steam distillation was used to remove water, continuously separating the oil layer at the bottom of the separator. The upper water layer was returned to the reactor. After observing that no obvious oily substances were found in the distilled condensate, the temperature was raised to 120℃ to remove most of the water, and then slightly cooled. Two parts of oxalic acid were added to the distillate, and the temperature was raised to 90℃ for 1.5 hours. Then, 200... After stirring 0 parts of methyl isobutyl ketone for 30 minutes, the mixture separated into layers. The oil layer was washed once with 100 parts of water and allowed to stand to separate into layers. The upper layer consisted of 2808.4 parts of phenol / p-ethylphenol solution (containing 339.3 parts of phenol, 397.3 parts of p-ethylphenol, 75.2 parts of 2,3-xylenol, 0.4 parts of m-ethylphenol, and 11.8 parts of oligomers), and the water layer consisted of 1501.9 parts of water (containing 2.3 parts of phenol, 0.4 parts of 2,3-xylenol, 1.6 parts of p-ethylphenol, and 4.2 parts of solvent).

[0045] Step 2: After removing free phenol / p-cresol, cool the material to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80~85℃, the time at 2h, and the final pressure at -0.075~-0.08Mpa. At the same time, observe the water level in the receiver, specifically ensuring that the water level remains constant within 20min. Collect 2159.8 parts of the recovered liquid (including: 30.3 parts of phenol, 20.1 parts of p-ethylphenol, 3.3 parts of 2,3-xylenol, and 3.6 parts of solvent).

[0046] Step 3: Gradually increase the vacuum to -0.095 MPa for 1.5 hours, while simultaneously increasing the temperature for dehydration. When the material temperature in the reactor reaches 190°C and no liquid distills out, maintain the temperature for 1 hour, stop dehydration, release the vacuum with nitrogen, and under nitrogen protection, release the hot material into a stainless steel pan for cooling, then crush and bag it to obtain 2523.3 parts of phenolic resin (softening point 110°C, free phenol 0.8%), with a color ranging from off-white to pale yellow. 3113.7 parts of the recovered liquid were obtained (including 37.1 parts of phenol, 22.8 parts of p-ethylphenol, and 4.2 parts of 2,3-xylenol).

[0047] Step 4: Add 2808.4 parts of phenol / p-ethylphenol solution to a stirred layering vessel, start stirring, add recovery solution 2 and recovery solution 3, stir for 0.5 hours, let stand for 1 hour, separate the layers, remove the lower layer water, and obtain 2925 parts of the upper layer methyl isobutyl ketone solution to be recovered (containing 439.3 parts of p-ethylphenol, 405.8 parts of phenol, 82.1 parts of 2,3-xylenol, and 11.8 parts of oligomers).

[0048] Step 5: 2925 parts of phenol / p-ethylphenol methyl isobutyl ketone solution were added to a distillation vessel with 30 trays. The mixture was heated to atmospheric pressure and then reduced pressure to remove 1986.6 parts of methyl isobutyl ketone (including 20.6 parts of phenol). The remaining material in the vessel was then transferred to a high-efficiency distillation column (180 theoretical trays) and subjected to reduced pressure distillation (-0.085 MPa, reflux ratio 10) to obtain 365.6 parts of 99.9% phenol and 504.4 parts of 99.8% 2,3-xylenol / p-ethylphenol (including 79.5 parts of 2,3-xylenol and 423.9 parts of p-ethylphenol). The remaining 12.7 parts of the vessel residue (including 11.8 parts of prepolymer) were returned to the polymerization reactor in the first step to be used with other phenolic substances for the next batch of phenolic resin synthesis.

[0049] Example 4

[0050] Step 1: In the reactor, turn on the stirrer and add 2000 parts of molten 99.2% coal-based phenol, 800 parts of m- and p-isopropylphenol (containing 35.5 parts of 3,4-xylenol, 2 parts of 2,3,6-trimethylphenol, 252 parts of p-isopropylphenol, 317.5 parts of m-isopropylphenol, 68 parts of p-propylphenol, 74.5 parts of m-propylphenol, 6.5 parts of 2,3-methylethylphenol, 26 parts of 3-ethyl-5-methylphenol, 14.5 parts of 2,3,5-trimethylphenol, 1.5 parts of 2,4 / 2,5-methylethylphenol, and 2 parts of 2,4,5-trimethylphenol), and 72 parts of oxalic acid in sequence. (Dissolve 100 parts in hot water). After feeding, measure the pH of the reaction solution with pH paper to 2.6. Adjust the reflux and venting devices, open the steam valve to raise the temperature, and the steam pressure should not exceed 0.3 MPa. At 90℃, add 2100 parts of 37% formaldehyde (the amount of formaldehyde is 0.935 times the total molar mass of phenol and m-isopropylphenol / m-isopropylphenol, 3-ethyl-5-cresol, and 2,3,5-trimethylphenol), and add the remaining 800 parts of m-p-isopropylphenol. The addition time is 3 hours. After the addition is complete, slowly raise the temperature. The heating rate should be strictly controlled within 1.5℃ / min to avoid overheating. Quickly; begin the reaction, maintaining the temperature at 95-100℃. After 1 hour of reaction, add 6 parts of 36% hydrochloric acid, maintain the temperature for 1.5 hours, and then take samples for analysis. Liquid chromatography analysis shows that m-isopropylphenol / m-propylphenol is 0.012% and phenol is 7.6%, which is acceptable. Open the valve of the condenser and separatory system, and use reflux steam distillation to remove water, continuously separating the oil layer at the bottom of the separator. Return the upper water layer to the reactor. After observing that there is no obvious oily substance in the distilled condensate, raise the temperature to 120℃ to remove most of the water, and then cool it slightly. Add 2 parts of oxalic acid to the distillate and raise the temperature to 90℃ for 1.5 hours, then add 1700 parts of... After stirring methyl isobutyl ketone for 1 hour, the mixture separated into layers. The oil layer was washed once with 100 parts of water and allowed to stand to separate. The upper layer consisted of 2315.2 parts of phenol / p-isopropylphenol solution (containing 220.7 parts of phenol, 26.2 parts of 3,4-xylenol, 292.5 parts of p-isopropylphenol, 74.9 parts of p-propylphenol, 4.9 parts of 2,3-methylethylphenol, 0.7 parts of other phenols, and 12.3 parts of prepolymer), and the water layer consisted of 1289.4 parts of water (containing 2.7 parts of phenol, 0.6 parts of 3,4-xylenol, 1.9 parts of p-isopropylphenol / propylphenol, 0.3 parts of other phenols, and 4.9 parts of solvent).

[0051] Step 2: After removing free phenol / p-cresol, cool the material to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80-85℃, the time at 2 hours, and the final pressure at -0.075 to -0.08 MPa. Observe the water level in the receiver, specifically ensuring the water level remains constant within 20 minutes. Collect 2176.8 parts of the recovered liquid (including: 27.6 parts of phenol, 3.7 parts of 3,4-xylenol, 42.2 parts of p-isopropylphenol, 12.6 parts of p-propylphenol, and 0.7 parts of other phenols).

[0052] Step 3: Divide the pre-dehydrated material into two portions and process them as follows:

[0053] One method involves gradually increasing the vacuum to -0.095 MPa over 2 hours, while simultaneously raising the temperature for dehydration. When the material temperature inside the vessel reaches 120°C and no liquid distillation occurs, the temperature is maintained for 1 hour, dehydration is stopped, the vacuum is released using nitrogen, and the hot material is discharged into a stainless steel pan under nitrogen protection, cooled, crushed, and bagged to obtain 1640 parts of phenolic resin (softening point 98°C, free phenol 1.9%), with a color ranging from off-white to pale yellow. 344.1 parts of the recovered liquid were obtained (containing 8.1 parts phenol, 0.8 parts 3,4-xylenol, 8.9 parts p-isopropylphenol, 3.3 parts p-propylphenol, and 0.2 parts other phenols).

[0054] One method involves gradually increasing the vacuum to -0.095 MPa for 2 hours, while simultaneously increasing the temperature for dehydration. When the material temperature inside the vessel reaches 200°C and no liquid distillation occurs, the temperature is maintained for 1 hour, dehydration is stopped, the vacuum is released with nitrogen, and the hot material is discharged into a stainless steel pan for cooling under nitrogen protection. The material is then crushed and bagged to obtain 1562.1 parts of phenolic resin (softening point 112°C, free phenol 0.7%), with a color ranging from off-white to pale yellow. 468.3 parts of the recovered liquid were obtained (including: 16 parts of phenol, 1.5 parts of 3,4-xylenol, 21.7 parts of p-isopropylphenol, 7.2 parts of p-propylphenol, and 0.3 parts of other phenols).

[0055] Step 4: Add 2315.2 parts of phenol / p-isopropylphenol solution to a stirred layering vessel, start stirring, add recovery solution 2, recovery solution 3, and recovery solution 4, stir for 1 hour, let stand for 1 hour, separate the layers, remove the lower layer of water, and obtain 2491.6 parts of the upper layer methyl isobutyl ketone solution to be recovered (containing 272.4 parts of phenol, 32.2 parts of 3,4-xylenol, 365.3 parts of p-isopropylphenol, 98 parts of p-propylphenol, 5.3 parts of 2,3-methylethylphenol, 0.9 parts of other phenols, and 12.3 parts of oligomers).

[0056] Step 5: 2491.6 parts of phenol / p-isopropylphenol methyl isobutyl ketone solution were added to a distillation vessel with 30 trays. The mixture was heated to atmospheric pressure and then reduced pressure to remove 1886.8 parts of methyl isobutyl ketone (including 18.9 parts of phenol). The remaining material in the vessel was then transferred to a high-efficiency distillation column (200 theoretical trays) and subjected to reduced pressure distillation (-0.085 MPa, reflux ratio 20) to obtain 242.8 parts of 99.8% phenol, 20.1 parts of 99.2% 3,4-xylenol, and 383.7 parts of 99.1% p-isopropylphenol / p-propylphenol (including 293.7 parts of p-isopropylphenol and 86.6 parts of p-isopropylphenol). The remaining 14.6 parts of the vessel residue (including 12.3 parts of prepolymer) were returned to the polymerization reactor in the first step to be used with other phenolic substances for the next batch of phenolic resin synthesis.

[0057] Example 5

[0058] Step 1: In the reactor, turn on the stirrer and add in the following order: 2000 parts of molten coal-derived 95.2% phenol, 1000 parts of mixed phenols (containing 716 parts of phenol and 284 parts of o-cresol), 300 parts of m-p-cresol (containing 132 parts of p-cresol, 139 parts of m-cresol, and 29 parts of o-ethylphenol), 300 parts of m-p-ethylphenol (containing 124 parts of p-ethylphenol, 133 parts of m-ethylphenol, 29 parts of 2,3-xylenol, 12 parts of 3,5-xylenol, 1 part of 2,4 / 2,5-xylenol, and 1 part of 2,4 / 2,5-methylethylphenol), and 300 parts of m-p-isopropylphenol (containing 13 parts of 3,4-xylenol, 1 part of 2,3,6-trimethylphenol, 120 parts of p-isopropylphenol, 147 parts of m-isopropylphenol, and 2,3-methylethylphenol). 0.5 parts of phenol, 10 parts of 3-ethyl-5-cresol, 5.5 parts of 2,3,5-trimethylphenol, 0.5 parts of 2,4 / 2,5-methylethylphenol, 0.5 parts of 2,4,5-trimethylphenol, 80 parts of oxalic acid (100 parts dissolved in hot water), and 10 parts of 85% phosphoric acid were added. After the feed was completed, the pH of the reaction solution was measured to be 2.8 using pH test paper. The reflux and venting devices were adjusted, and the steam valve was opened to raise the temperature. The steam pressure should not exceed 0.3 MPa. While the reactor temperature was at 95℃, 3250 parts of 37% formaldehyde (the amount of formaldehyde was 1 times the total molar mass of phenol, m-cresol, m-ethylphenol, 3,5-xylenol, m-isopropylphenol, 3-ethyl-5-cresol, and 2,3,5-trimethylphenol) were added dropwise. The remaining second component 1400 parts (500 parts of mixed phenol, m-p-methylphenol, m-ethylphenol, m-ethylphenol, m-ethylphenol, m-isopropylphenol, m-ethyl-5-cresol ... Add 300 parts of phenol, 300 parts of m- and p-ethylphenol, and 300 parts of m- and p-isopropylphenol over 3 hours, and slowly raise the temperature after addition. Strictly control the heating rate within 1.5℃ / min to avoid excessive heating. Begin the reaction by maintaining the temperature at 95-100℃, stabilizing at 98℃, and holding for 3 hours. Sampling and analysis are performed; liquid chromatography analysis shows that m-cresol / m-ethylphenol / m-isopropylphenol are 0.04% and phenol is 9.85%, which is acceptable. Open the valve of the condenser and separatory system, and use reflux steam distillation to remove water, continuously separating the oil layer at the bottom of the separator. Return the upper water layer to the reactor. After observing that there is no obvious oil in the distilled condensate, raise the temperature to 130℃ to remove most of the water, and then slightly lower the temperature. Add 2.5 parts of oxalic acid to the distilled water layer and react at 80℃ for 2 hours. Continue the reaction... After treatment, 2000 parts of ethyl acetate were added to the aqueous layer and stirred for 30 minutes to separate the layers. The oil layer was washed once with 50 parts of water and allowed to stand to separate. The upper layer consisted of 3449.3 parts of ethyl acetate solution of phenol / p-cresol / p-ethylphenol / p-isopropylphenol (containing 328.2 parts of phenol, 419.5 parts of o-cresol, 200.8 parts of p-cresol, 47.5 parts of o-ethylphenol, 200.5 parts of p-ethylphenol, 47.7 parts of 2,3-xylenol, 22.9 parts of 3,4-xylenol, 190.7 parts of p-isopropylphenol, 4.7 parts of other phenols, and 18.8 parts of prepolymer). The aqueous layer consisted of 2708.1 parts of phenol (containing 86.5 parts of phenol, 12.2 parts of o-cresol, 8.9 parts of p-cresol, 3.3 parts of o-ethylphenol, 1.1 parts of p-ethylphenol, and 0.(8 parts, 3,4-xylenol 0.4 parts, p-isopropylphenol 0.7 parts, other phenols 0.4 parts, solvent 13.2 parts).

[0059] Step 2: After removing free phenol / p-cresol, cool the material to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80-85℃, the time at 2 hours, and the final pressure at -0.075 to -0.08 MPa. Simultaneously observe the water level in the receiver, ensuring it remains constant for 20 minutes. Collect 2,231 parts of the recovered liquid (including: 45.4 parts of phenol, 15.5 parts of o-cresol, 13.3 parts of p-cresol, 3.1 parts of o-ethylphenol, 9.2 parts of p-ethylphenol, 1.9 parts of 2,3-xylenol, 0.8 parts of 3,4-xylenol, 2.9 parts of p-isopropylphenol, and 1.1 parts of other phenols).

[0060] Step 3: Gradually increase the vacuum to -0.095 MPa for 1.5 hours, while simultaneously increasing the temperature for dehydration. When the material temperature in the reactor reaches 210°C and no liquid distills out, maintain the temperature for 1 hour, stop dehydration, release the vacuum with nitrogen, and under nitrogen protection, release the hot material into a stainless steel pan for cooling, then crush and bag it to obtain 4087 parts of phenolic resin (softening point 113°C, free phenol 0.6%), with a color ranging from off-white to pale yellow. 3128.8 parts of the recovered liquid were obtained (including: 26.8 parts of phenol, 16.2 parts of o-cresol, 8.7 parts of p-cresol, 1.8 parts of o-ethylphenol, 2.9 parts of p-ethylphenol, 1.3 parts of 2,3-xylenol, 0.7 parts of 3,4-xylenol, 2.5 parts of p-isopropylphenol, and 2.1 parts of other phenols).

[0061] Step 4: Add 3449.3 parts of the ethyl acetate solution of phenol / p-cresol / p-ethylphenol / p-isopropylphenol (containing 347 parts of phenol, 419.5 parts of o-cresol, 200.8 parts of p-cresol, 47.5 parts of o-ethylphenol, 200.5 parts of p-ethylphenol, 47.7 parts of 2,3-xylenol, 22.9 parts of 3,4-xylenol, 190.7 parts of p-isopropylphenol, and 4.7 parts of other phenols) to a stirred tank, start stirring, and add the recovery liquid. 2 and the recovered liquid 3 were stirred for 1 hour, allowed to stand for 1 hour, separated into layers, and the lower layer of water was removed to obtain 3587 parts of the upper layer ethyl acetate solution to be recovered (containing 396.3 parts of phenol, 448.0 parts of o-cresol, 221.6 parts of p-cresol, 52.1 parts of o-ethylphenol, 210.5 parts of p-ethylphenol, 50.4 parts of 2,3-xylenol, 24.3 parts of 3,4-xylenol, 195.1 parts of p-isopropylphenol, 7.8 parts of other phenols, and 18.8 parts of prepolymer).

[0062] Step 5: Add 3587 parts of the phenol / p-cresol / p-ethylphenol / p-isopropylphenol ethyl acetate solution to a distillation vessel with 40 trays. Heat to atmospheric pressure, then reduce pressure to remove 1952.2 parts of ethyl acetate (including 23.7 parts of phenol). Transfer the remaining material in the vessel to a high-efficiency distillation column (180 theoretical trays) and distill under reduced pressure (-0.085 MPa, reflux ratio 20) to obtain 354.1 parts of 99.8% phenol, 384.6 parts of 99.6% o-cresol, and 246 parts of 99.5% p-cresol / o-ethylphenol. 0.8 parts (including 198.9 parts of p-cresol and 46.7 parts of o-ethylphenol), 236.1 parts of 99.6% 2,3-xylenol / p-ethylphenol (including 45.4 parts of 2,3-xylenol and 189.8 parts of p-ethylphenol), 178.8 parts of 99.1% 3,4-xylenol / p-isopropylphenol (including 19.1 parts of 3,4-xylenol and 158.1 parts of p-isopropylphenol), and 22.1 parts of reactor residue (containing 18.8 parts of prepolymer) were returned to the first-step polymerization reactor to be used together with other phenolic substances for the next batch of phenolic resin synthesis.

[0063] 99.5% p-cresol / o-ethylphenol can be separated by alkylation to obtain antioxidant 2,6-di-tert-butyl-p-cresol and 99% o-ethylphenol; 99.6% 2,3-xylenol / p-ethylphenol can be separated by alkylation to obtain antioxidant 2,6-di-tert-butyl-p-ethylphenol and 99% 2,3-xylenol; 99.1% 3,4-xylenol / p-isopropylphenol can be separated by alkylation to obtain 99% 3,4-xylenol and 98% p-isopropylphenol.

[0064] Comparative Example 1

[0065] Step 1: In the reactor, start stirring and sequentially add 2000 parts of 99.9% molten petrochemical-grade phenol and 30 parts of oxalic acid (30 parts dissolved in hot water). After feeding, measure the pH of the reaction solution to be 3.5-4, adjust the reflux and venting devices, maintain the liquid temperature at 51℃, open the steam valve to raise the temperature, ensuring the steam pressure does not exceed 0.3 MPa, and gradually add 1535 parts of 37% formaldehyde (the amount of formaldehyde is 0.89 times the molar amount of phenol) at 90℃ over 2 hours. After addition, slowly raise the temperature. Temperature; the heating rate is strictly controlled within 1.5℃ / min, with a set rate of 1.0℃ / min, to avoid excessive heating, which could cause the reaction liquid to overflow and affect the resin quality; the temperature is raised to 98℃, held for 4 hours, and then sampled for analysis. Gel chromatography analysis showed phenol content of 13.6%; the valve of the condenser separation system is opened, and the reflux water vapor is distilled to remove water, continuously separating the oil layer at the bottom of the separator. The upper water layer is returned to the reactor. After observing that there are no obvious oily substances in the distilled condensate, the temperature is raised to 120℃ to remove most of the water;

[0066] Step 2: Cool the reactants to 80℃, adjust the vacuum device, and start vacuum dehydration. Control the dehydration temperature at 80~85℃, the time at 2.5h, and the final pressure at -0.075~-0.08Mpa. At the same time, observe the water level in the receiver, and make sure the water level remains constant within 20 minutes.

[0067] Step 3: Gradually increase the vacuum to -0.095 MPa for 1.5 hours, while simultaneously increasing the temperature to further dehydrate. When the material temperature in the reactor reaches 210°C and no liquid distills out, maintain the temperature for 1 hour, stop dehydration, release the vacuum with nitrogen, and under nitrogen protection, release the hot material into a stainless steel pan to cool, then crush and bag it to obtain 1975.7 parts of thermoplastic phenolic resin (softening point 109°C, free phenol 0.9%), with a color ranging from off-white to pale yellow, and a total of 1471.5 parts of liquid were extracted.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0069] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A method for synthesizing phenolic resin by acid synthesis and simultaneously extracting para-phenol, characterized in that, Includes the following steps: (1) Phenolic resin synthesis and crude separation of para-phenol: Using acid as a catalyst, a mixed phenol containing a first component and a second component is selectively polymerized with aldehydes; the first component is phenol or a mixed phenol composed of phenol and o-cresol; the second component is at least one of m-p-cresol, m-p-ethylphenol, and m-p-isopropylphenol; by controlling the reaction depth, the meta-phenol in the second component is basically completely reacted, while the para-phenol in the first component and the second component is partially residual; after the reaction, the distillate containing unreacted phenol is separated by distillation, and the distillate is extracted to obtain an oil phase mixture rich in phenol and at least one of p-cresol, p-ethylphenol, and p-isopropylphenol; (2) Refining of para-phenol: The oil phase mixture obtained in step (1) is subjected to distillation to separate phenol and at least one of para-cresol, para-ethylphenol and para-isopropylphenol.

2. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the mass ratio of the first component to the second component is 20:80 to 100:

0.

3. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In the first component, when it is phenol, its phenol content is ≥90%, o-cresol is ≤10%, and 2,6-xylenol is ≤0.5%; when it is a mixed phenol, it is composed of 50-90% phenol and 10-50% o-cresol by mass, and 2,6-xylenol is ≤0.5%.

4. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, The second component satisfies one of the following conditions: a. When it is m-p-cresol, the total content of m-cresol, p-cresol, and o-ethylphenol is ≥98%, o-ethylphenol is ≤12%, o-cresol is ≤1%, 2,6-xylenol is ≤2%, and 2,4- / 2,5-xylenol is ≤1%; b. When it is m- or p-ethylphenol, the total content of 2,3-xylenol, m-ethylphenol, p-ethylphenol and 3,5-xylenol is ≥98%, 3,5-xylenol is ≤10%, 2,4- / 2,5-methylethylphenol is ≤1%, 2,4- / 2,5-xylenol is ≤1%, and 2,4,6-trimethylphenol is ≤1%; c. When the substance is m- or p-isopropylphenol, the total content of 2,3-methylethylphenol, m-isopropylphenol, m- or p-propylphenol and 3-ethyl-5-methylphenol is ≥90%, 3,4-xylenol is ≤5%, 2,3,5-trimethylphenol is ≤5%, 2,4- / 2,5-methylethylphenol is ≤1%, 2,4,5-trimethylphenol is ≤1%, 2,4,6-trimethylphenol is ≤1%, and 2,3,6-trimethylphenol is ≤1%.

5. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the catalyst is selected from one or more of oxalic acid, formic acid, phosphoric acid, hydrochloric acid, aminosulfonic acid, and benzenesulfonic acid, and its addition amount is 0.1 to 5% of the total mass of the mixed phenols.

6. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the aldehyde is an aqueous formaldehyde solution or paraformaldehyde; the total molar ratio of the aldehyde to the phenols with two or more reactive sites in the mixed phenols is 0.5:1 to 1.5:

1.

7. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the solvent used for extraction is toluene or methyl isobutyl ether, and its amount is 0.5 to 2 times the total mass of the raw material phenolic substances.

8. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the control of reaction depth is achieved by the following method: the reaction is carried out at 80-100°C, and when the sample analysis shows that the content of m-cresol, m-ethylphenol and / or m-isopropylphenol is ≤1% and the phenol content is 5-20%, the reaction is terminated and the distillation separation step is initiated.

9. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (1), the aqueous phase rich in phenol obtained from the distillate is supplemented with an acid catalyst accounting for 0.01 to 0.1% of the total mass of the mixed phenols, and after reflux reaction at 80 to 110°C for 1 to 3 hours, it is then extracted with the solvent.

10. The method for synthesizing phenolic resin by acid method and simultaneously extracting para-phenol according to claim 1, characterized in that, In step (2), the residue obtained after distillation is used as a prepolymer and returned to the polymerization reactor in step (1) for recycling.