Method for extracting o-isopropyl phenol and 2-ethyl-6-cresol

Abstract

The invention discloses a method for extracting o-isopropyl phenol and 2-ethyl-6-cresol, which comprises the following steps: adding a 2, 4 / 2, 5-xylenol mixture containing o-isopropyl phenol and 2-ethyl-6-cresol, a catalyst and diisobutylene into a reactor for reaction; the method comprises the following steps of: sampling and analyzing to be qualified, filtering, carrying out low-vacuum reduced pressure distillation on filtrate to obtain diisobutylene and the previous component for mechanical application, and then carrying out improved vacuum reduced pressure distillation to sequentially obtain 99% of 2, 5-xylenol, 99% of 6-isooctyl-2, 4-xylenol and 99% of 4-isooctyl-2-ethyl-6-cresol and a kettle residue of 4, 6-diisooctyl-2-isopropyl phenol; the method comprises the following steps: respectively decomposing 2, 4-isooctyl-2-ethyl-6-cresol and 4, 6-di-tert-butyl-2-isopropyl phenol under the catalysis of acid to obtain crude 2-ethyl-6-cresol and o-isopropyl phenol, mechanically applying corresponding diisobutylene obtained by decomposition to next reaction, and rectifying again to obtain 99% 2-ethyl-6-cresol and o-isopropyl phenol; the 2, 4 / 2, 5-xylenol contains cresol, m-p-cresol, m-p-ethyl phenol and other cresol, so that the influence on separation and extraction of o-isopropyl phenol and the like is small, and the process practicability is high.

Description

Technical Field

[0001] The present invention relates to a method for extracting phenols, specifically a method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol, and belongs to the technical field of coal coking and organic product separation. Background Art

[0002] The traditional synthesis method of o-isopropylphenol is mainly obtained by sulfonation and alkali fusion of isopropylbenzene, and can also be synthesized by reacting phenol with isopropanol under the catalysis of phenol aluminum. The most direct method is also the fixed-bed catalytic alkylation of phenol and isopropanol to synthesize o-isopropylphenol. The above methods for synthesizing o-isopropylphenol have more by-products and large pollution. Coupled with a relatively large amount of by-product diisopropylphenol (the market of diisopropylphenol is not as good as that of o-isopropylphenol), it is difficult to produce in large quantities.

[0003] 2-Ethyl-6-methylphenol can be obtained by reacting o-cresol with ethanol in a fixed bed equipped with an alkylation catalyst, but there are two problems: one is that the reaction rate is relatively low (significantly lower than the methylation reaction of methanol), and the other is that there are many by-products such as 4-ethyl-2-methylphenol and 2,4-diethyl-6-methylphenol. Therefore, the reaction yield is low, the energy consumption is high, and the operating cost remains high. Coupled with the relatively small market consumption of 2-ethyl-6-methylphenol, the economic feasibility of producing this product by fixed-bed catalytic ethylation is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol to solve the above problems. Using crude phenol or industrial xylenol as raw materials (mainly crude phenol extracted from pyrolytic phenol-containing coal tar), rectifying to obtain a 2,4 / 2,5-xylenol fraction with a content of more than 80%, which contains about 5-20% of o-isopropylphenol and 2-ethyl-6-methylphenol. We consider separating 2-ethyl-6-methylphenol and o-isopropylphenol from 2,4 / 2,5-xylenol to obtain pure o-isopropylphenol and 2-ethyl-6-methylphenol. The idea of the present invention is clear, the operation is simple and feasible, the three wastes are less, and the production cost is low.

[0005] The present invention relates to a process for extracting o-isopropylphenol and 2-ethyl-6-methylphenol, comprising the following steps: Step 1: Isooctylation reaction. Charge a mixture of 2,4 / 2,5-xylenol with a certain composition, a catalyst, diisobutylene or isooctene into a reactor, and react at a certain temperature for 2 to 12 hours. Take a sample for analysis. It is qualified if 6-isooctyl-2-isopropylphenol ≤ 0.5%. Filter or neutralize to pH 7 - 8. First, distill off diisobutylene and the previous fraction for reuse under reduced pressure from the filtrate, and then increase the vacuum for vacuum rectification to obtain 99% 2,5-xylenol, 99% 6-isooctyl-2,4-xylenol, and 99% 4-isooctyl-2-ethyl-6-methylphenol in sequence. The residue in the kettle is 4,6-diisooctyl-2-isopropylphenol. Among them, 99% 2,5-xylenol and 99% 6-isooctyl-2,4-xylenol can be used as antioxidants and polymerization inhibitors; Step 2: Deisooctylation reaction. 99% 4-isooctyl-2-ethyl-6-methylphenol and the residue in the kettle, 4,6-di-tert-butyl-2-isopropylphenol, are decomposed at 160 - 200°C under the catalysis of sulfuric acid to obtain crude 2-ethyl-6-methylphenol and o-isopropylphenol. The decomposed isooctene is recycled to the next corresponding isooctylation reaction. The materials are added to a rectification column for vacuum rectification to obtain 99% 2-ethyl-6-methylphenol and 99% o-isopropylphenol.

[0006] Preferably, in Step 1, a mixture of 2,4 / 2,5-xylenol with a certain composition, a catalyst, diisobutylene or isooctene is charged into the reactor. In the 2,4 / 2,5-xylenol mixture, o-isopropylphenol is 1 - 30%, and 2-ethyl-6-methylphenol is 1 - 20%. Preferably, o-isopropylphenol is 10 - 20% and 2-ethyl-6-methylphenol is 5 - 10%.

[0007] Preferably, in Step 1, a mixture of 2,4 / 2,5-xylenol with a certain composition, a catalyst, diisobutylene or isooctene is charged into the reactor. The catalyst is inorganic acid, organic acid, acidic resin, solid acid, etc. Preferably, it is a strongly acidic resin.

[0008] Preferably, the dosage of the catalyst is 1 - 30%.

[0009] Preferably, in Step 1, a mixture of 2,4 / 2,5-xylenol with a certain composition, a catalyst, diisobutylene or isooctene is charged into the reactor. The dosage of diisobutylene or isooctene is 1 - 10 times the mass of the raw material 2,4 / 2,5-xylenol mixture. Preferably, it is 2 - 5 times.

[0010] Preferably, in Step 1, the reaction is carried out at a certain temperature for 2 to 12 hours. The certain temperature is 60 - 150°C. Preferably, it is 100 - 120°C.

[0011] Preferably, in the second step, 99% 4-isooctyl-2-ethyl-6-methylphenol and the kettle residue 4,6-di-tert-butyl-2-isopropylphenol are decomposed at 160-200 °C under the catalysis of sulfuric acid to obtain crude 2-ethyl-6-methylphenol and o-isopropylphenol. The sulfuric acid content is 92-98%, and the dosage of sulfuric acid is 0.5-5% of the mass of 99% 4-isooctyl-2-ethyl-6-methylphenol or the kettle residue.

[0012] Preferably, in the first step, the filtrate is first subjected to vacuum rectification to distill off diisobutylene and the front portion is recycled. The vacuum rectification pressure is -0.05 to -0.08 MPa, and the reflux ratio is 1-5:1.

[0013] Preferably, in the first step, then the vacuum is increased for vacuum rectification. The vacuum rectification pressure is -0.09 to -0.1 MPa, and the reflux ratio is 5-15:1.

[0014] Preferably, in the second step, the material is added to a rectification column for vacuum rectification. The vacuum rectification pressure is -0.08 to -0.09 MPa, and the reflux ratio is 5-10:1.

[0015] Beneficial effects:

[0016] 1. The reaction rate of the synthesis of o-isopropylphenol by the catalytic propylation of phenol and isopropanol in a fixed bed is relatively slow, and at the same time, more 2,6-diisopropylphenol is produced as a by-product. The production cost and separation equipment are relatively large, and the investment is large. Moreover, for products with a small demand for o-isopropylphenol, the fixed bed catalytic alkylation emphasizes economies of scale. The separation and production of o-isopropylphenol in the present invention has the advantages of cheap raw material prices, low treatment costs, less equipment investment, high separation efficiency, being suitable for the production of small batches of products, and having good economic benefits.

[0017] 2. When o-cresol and ethanol are catalytically propylated in a fixed bed to synthesize 2-ethyl-6-methylphenol, more 4-ethyl-2-methylphenol is produced as a by-product. The production cost and separation equipment are relatively large, and the investment is large. Moreover, the market demand for 2-ethyl-6-methylphenol is relatively small. The fixed bed catalytic alkylation emphasizes economies of scale. The separation and production of 2-ethyl-6-methylphenol in the present invention has the advantages of cheap raw material prices, low treatment costs, less equipment investment, high separation efficiency, being suitable for the production of small batches of products, and having good economic benefits.

[0018] 3. The present invention has low requirements for the quality of raw materials. The presence of m,p-cresol, m,p-ethylphenol and other impurity phenols in 2,4 / 2,5-xylenol has little influence on the separation and extraction of o-isopropylphenol and the like, and the process has strong practicability.

[0019] 4. While extracting o-isopropylphenol and 2-ethyl-6-methylphenol from coal chemical products, products such as antioxidant 6-isooctyl-2,4-xylenol and 2,5-xylenol can also be separated. Since the price of the mixed 2,4 / 2,5-xylenol containing o-isopropylphenol and 2-ethyl-6-methylphenol is 5,000 yuan / ton, which is much lower than 40,000 yuan / ton of 99% 2,4-xylenol, the co-production cost is lower and the market competitiveness is stronger. Detailed implementation mode

[0020] Example 1

[0021] Add 1350 parts of 2,4 / 2,5-xylenol mixture (including 593 parts of 2,4-xylenol, 369 parts of 2,5-xylenol, 240 parts of o-isopropylphenol, and 148 parts of 2-ethyl-6-methylphenol), 270 parts of strongly acidic resin, and 4000 parts of diisobutylene into the reactor. Start stirring and heat up to 110 °C for reaction for 8 hours. Take samples for analysis. When the content of 6-isooctyl-2-isopropylphenol is 0.29%, it is qualified. Filter the filter cake for reuse. First, distill the filtrate at -0.07 MPa and a reflux ratio of 3 - 5:1 to recover 2829.3 parts of the previous fractions such as diisobutylene. Then, carry out vacuum distillation at -0.098 MPa and a reflux ratio of 5 - 15:1 to obtain 353.8 parts of 2,5-xylenol with a content of 99.5%, 1105.2 parts of 6-isooctyl-2,4-xylenol with a content of 99.2%, and 253.8 parts of 4-isooctyl-2-ethyl-6-methylphenol with a content of 99.2%; the residue in the kettle is 630.3 parts (627.1 parts of 4,6-diisooctyl-2-isopropylphenol).

[0022] Add the residue in the kettle into the decomposition kettle, add 8 parts of concentrated sulfuric acid, heat up to 180 °C with stirring and maintain for 4 hours. Stop the reaction when the content of 6-isooctyl-2-isopropylphenol in the gas chromatogram detection is 0.36%. Slightly cool down and neutralize to pH 7.5 with 20.7 parts of liquid caustic soda. Carry out vacuum distillation to obtain 230 parts of o-isopropylphenol with a content of 99.5%, the recovery rate is 96.6%, and 382.4 parts of recycled diisobutylene are reused.

[0023] Add 253.8 parts of 4-isooctyl-2-ethyl-6-methylphenol with a content of 99.2% into the decomposition kettle, add 2.5 parts of concentrated sulfuric acid, heat up to 195 °C with stirring and maintain for 2 hours. Stop the reaction when the content of 4-isooctyl-2-ethyl-6-methylphenol in the gas chromatogram detection is 0.09%. Slightly cool down and neutralize to pH 7.5 with 6.6 parts of 31% sodium hydroxide aqueous solution (liquid caustic soda). Carry out vacuum distillation to obtain 133.1 parts of 2-ethyl-6-methylphenol with a content of 99.4%, the recovery rate is 95.8%, and 111.4 parts of recycled diisobutylene are reused.

[0024] Example 2

[0025] Add 4000 parts of a 2,4 / 2,5-xylenol mixture (containing 1500 parts of 2,4-xylenol, 1390 parts of 2,5-xylenol, 860 parts of o-isopropylphenol, and 250 parts of 2-ethyl-6-methylphenol), 120 parts of 98% sulfuric acid, and 6000 parts of diisobutene into a pressure vessel. Seal the reaction kettle, start stirring, and heat up to 120 °C for reaction for 6 hours. Take a sample for analysis. When the content of 6-isooctyl-2-isopropylphenol is 0.17%, it is qualified. Cool down to 70 °C, empty the reaction kettle, and then add 31% liquid alkali (aqueous sodium hydroxide solution) to neutralize to pH 7-8. First, distill the filtrate at -0.07 MPa and a reflux ratio of 3-5:1 to recover 2827.6 parts of the front fractions such as diisobutene. Then, conduct vacuum distillation at -0.098 MPa and a reflux ratio of 5-15:1 to obtain 1348.1 parts of 2,5-xylenol with a content of 99.6%, 2769.9 parts of 6-isooctyl-2,4-xylenol with a content of 99.4%, and 431 parts of 4-isooctyl-2-ethyl-6-methylphenol with a content of 99.1%. The residue in the kettle is 2268.1 parts (2253.7 parts of 4,6-diisooctyl-2-isopropylphenol).

[0026] Add the residue in the kettle into a decomposition kettle, add 25 parts of concentrated sulfuric acid, heat up to 190 °C with stirring and maintain for 3 hours. Stop the reaction when the content of 6-isooctyl-2-isopropylphenol in the gas chromatogram detection is 0.26%. Cool down slightly and neutralize with 64.5 parts of 31% liquid alkali to pH 7.5. Conduct vacuum distillation to obtain 830 parts of o-isopropylphenol with a content of 99.3%, and the recovery rate is 96.8%. Recover 1388 parts of diisobutene for reuse.

[0027] Add 431 parts of 4-isooctyl-2-ethyl-6-methylphenol with a content of 99.1% into a decomposition kettle, add 4 parts of concentrated sulfuric acid, heat up to 195 °C with stirring and maintain for 2 hours. Stop the reaction when the content of 4-isooctyl-2-ethyl-6-methylphenol in the gas chromatogram detection is 0.11%. Cool down slightly and neutralize with 10.5 parts of liquid alkali to pH 8. Conduct vacuum distillation to obtain 225.2 parts of 2-ethyl-6-methylphenol with a content of 99.6%, and the recovery rate is 94.9%. Recover 192.6 parts of diisobutene for reuse.

[0028] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0029] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol, characterized in that, It includes the following steps: Step 1: Isooctylation reaction. Put a 2,4 / 2,5-xylenol mixture with a certain composition, a catalyst, diisobutylene or isooctene into a reactor, react at a certain temperature for 2 to 12 hours, take samples for analysis, and require that 6-isooctyl-2-isopropylphenol ≤ 0.5% to be qualified. Filter or neutralize to pH 7 - 8. First, distill off diisobutylene and the previous portion under reduced pressure for recycling in the filtrate, and then increase the vacuum for vacuum rectification to obtain 99% 2,5-xylenol, 99% 6-isooctyl-2,4-xylenol, and 99% 4-isooctyl-2-ethyl-6-methylphenol in sequence. The residue in the kettle is 4,6-diisooctyl-2-isopropylphenol. Among them, 99% 2,5-xylenol and 99% 6-isooctyl-2,4-xylenol can be used as antioxidants and polymerization inhibitors; Step 2: Deisooctylation reaction. 99% 4-isooctyl-2-ethyl-6-methylphenol and the residue in the kettle, 4,6-di-tert-butyl-2-isopropylphenol, are decomposed at 160 - 200 °C under the catalysis of sulfuric acid to obtain crude 2-ethyl-6-methylphenol and o-isopropylphenol. The decomposed isooctene is recycled to the next corresponding isooctylation reaction. The materials are added to a rectification column for vacuum rectification to obtain 99% 2-ethyl-6-methylphenol and 99% o-isopropylphenol.

2. The method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, wherein In Step 1, put a 2,4 / 2,5-xylenol mixture with a certain composition, a catalyst, diisobutylene or isooctene into the reactor. In the 2,4 / 2,5-xylenol mixture, o-isopropylphenol is 1 - 30% and 2-ethyl-6-methylphenol is 1 - 20%. Preferably, o-isopropylphenol is 10 - 20% and 2-ethyl-6-methylphenol is 5 - 10%.

3. The method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, wherein In Step 1, put a 2,4 / 2,5-xylenol mixture with a certain composition, a catalyst, diisobutylene or isooctene into the reactor. The catalyst is inorganic acid, organic acid, acidic resin, solid acid, etc. Preferably, it is a strongly acidic resin.

4. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 3, characterized in that, The dosage of the catalyst is 1 - 30%.

5. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In Step 1, put a 2,4 / 2,5-xylenol mixture with a certain composition, a catalyst, diisobutylene or isooctene into the reactor. The dosage of diisobutylene or isooctene is 1 - 10 times the mass of the raw material 2,4 / 2,5-xylenol mixture. Preferably, it is 2 - 5 times.

6. The method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In Step 1, react at a certain temperature for 2 to 12 hours. The certain temperature is 60 - 150 °C. Preferably, it is 100 - 120 °C.

7. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In Step 2, 99% 4-isooctyl-2-ethyl-6-methylphenol and the residue in the kettle, 4,6-di-tert-butyl-2-isopropylphenol, are decomposed at 160 - 200 °C under the catalysis of sulfuric acid to obtain crude 2-ethyl-6-methylphenol and o-isopropylphenol. The sulfuric acid content is 92 - 98%, and the dosage of sulfuric acid is 0.5 - 5% of the mass of 99% 4-isooctyl-2-ethyl-6-methylphenol or the residue in the kettle.

8. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In Step 1, first distill off diisobutylene and the previous portion under reduced pressure for recycling in the filtrate. The pressure of the vacuum rectification is -0.05 - -0.08 MPa and the reflux ratio is 1 - 5:

1.

9. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In Step 1, then increase the vacuum for vacuum rectification. The pressure of the vacuum rectification is -0.09 - -0.1 MPa and the reflux ratio is 5 - 15:

1.

10. A method for extracting o-isopropylphenol and 2-ethyl-6-methylphenol according to claim 1, characterized in that, In the second step, the material is added into the rectifying column for vacuum rectification. The vacuum rectification pressure is -0.08 to -0.09 MPa, and the reflux ratio is 5 to 10:1.