CN120192215A

CN120192215A - A process for preparing phenolic products using 2,4-dimethylphenol/2,5-dimethylphenol

Info

Publication number: CN120192215A
Application number: CN202510438072.2A
Authority: CN
Inventors: 阎春平; 王继斌; 王旋; 阎许文馨; 黄怿夏
Original assignee: Shaanxi Basiteng Technology Co ltd
Current assignee: Shaanxi Basiteng Technology Co ltd
Priority date: 2025-04-09
Filing date: 2025-04-09
Publication date: 2025-06-24

Abstract

The invention discloses a process for preparing phenol products from 2, 4-xylenol/2, 5-xylenol, which comprises the steps of adding a 2, 4-xylenol/2, 5-xylenol mixture into a reactor with silicon-aluminum-chromium oxide and an acidic catalyst, carrying out dealkylation reaction at 280-400 ℃, removing propylene, ethylene and the like from o-isopropyl phenol, 2-methyl-6-ethylphenol and the like in the reaction to obtain a mixed phenol and olefin mixture containing phenol, cresol, 2, 4-xylenol/2, 5-xylenol, quickly cooling and liquefying the mixture to discharge olefin, rectifying to obtain high-purity 2, 5-xylenol/2, 4-xylenol with the o-isopropyl phenol, 2-ethyl-6-cresol and the like removed, carrying out reaction on propylene and m-cresol to obtain thymol, 4-isopropyl-3-cresol and the like by controlling the reaction temperature, and obtaining o-ethylphenol and p-ethylphenol by removing isopropyl phenol and isopropyl phenol in the 2-ethyl-6-cresol in the high-ethyl-cresol, and purifying the 2, 5-xylenol to obtain the products.

Description

Process for preparing phenol products from 2, 4-xylenol/2, 5-xylenol

Technical Field

The invention relates to a process for preparing a phenol product, in particular to a process for preparing a phenol product from 2, 4-xylenol/2, 5-xylenol, belonging to the technical field of organic synthesis and separation.

Background

The crude phenol is rectified to obtain phenol, o-cresol, triple-mixed cresol, m-cresol containing m-p-cresol with the meta position of 55%, m-p-cresol with the meta position of 99% and industrial xylenol, which are not well refined and separated, and the industrial xylenol can be rectified to obtain more than 80% of 2, 4-xylenol/2, 5-xylenol mixed phenol, wherein the mixed phenol contains part of o-isopropyl/propyl phenol, 2-ethyl-6-cresol and the like, and the impurities such as the 2, 4-xylenol/2, 5-xylenol and the like have relatively high ratio in xylenol and relatively high quantity, so that the performance and application of the 2, 4-xylenol/2, 5-xylenol are influenced by the existence of the impurities such as the o-isopropyl phenol/o-propyl phenol and the 2-ethyl-6-cresol, which are required to be considered to be separated from the 2, 4-xylenol/2, 5-xylenol mixture.

The crude phenol extracted from high temperature coal tar has high content of 2, 4-xylenol/2, 5-xylenol, but the crude phenol extracted from high temperature coal tar has low content of o-isopropyl phenol/o-propyl phenol and 2-methyl-6-ethyl phenol, so that the separation and application of 2, 4-xylenol/2, 5-xylenol are not affected, the crude phenol obtained from medium and low temperature gasification has low content of 2, 4-xylenol/2, 5-xylenol, low content of o-isopropyl phenol/o-propyl phenol and 2-ethyl-6-cresol, the separation and application of p-2, 4-xylenol/2, 5-xylenol are not affected too much, the economical efficiency of separating 2, 4-xylenol/2, 5-xylenol is not good, the 2, 4-xylenol/2, 5-xylenol content in the crude phenol extracted from medium and low temperature phenol-containing coal tar is not affected, the o-isopropyl phenol/o-propyl phenol and 2-methyl-6-ethyl phenol are also high, the 2, 4-xylenol/2, 5-xylenol is not produced, the product of high purity 2, 4-xylenol/2, 5-xylenol is not affected, the tert-butyl phenol and the tert-butyl-2, 4-xylenol is difficult to be separated from tert-butyl-2, 4-xylenol and 4-tert-butyl-2, 5-xylenol is difficult to develop, and the method of 2, 4-tert-butyl-4-xylenol has a high boiling point.

Disclosure of Invention

The invention aims to provide a process for preparing phenol products from 2, 4-xylenol/2, 5-xylenol, which aims to solve the problems that phenol products in traditional phenol-containing coal tar are generally required to be extracted by rectifying and cutting phenol-containing coal tar to obtain 170-230 ℃ phenol oil fractions, the phenol oil fractions are used for extracting crude phenol and dephenolized phenol oil by an alkali dissolution acid precipitation method or a solvent extraction method, the crude phenol is refined to obtain various phenol products or mixtures, and then mixed phenol (the mixture of phenol and o-cresol), o-cresol fractions (containing 2, 6-xylenol), m-cresol, mixed xylenol and the like are separated by a physical or chemical method to obtain phenol, o-cresol, m-cresol, p-cresol, 2, 5-xylenol, 2, 4-xylenol, 3, 5-xylenol, 3, 4-xylenol, m-ethylphenol, p-ethylphenol and the like, the process is complex, and the economic benefit is poor.

The invention relates to a process for preparing a phenol product from 2, 4-xylenol/2, 5-xylenol, which comprises the following steps:

Step one, cracking and translocation reaction:

Filling an acidic silicon-aluminum-chromium oxide solid catalyst and zirconium phosphate into a stainless steel high-pressure reactor, adding a2, 4-xylenol/2, 5-xylenol mixture, sealing, heating to 280-400 ℃ for reaction for 3-10 hours, gradually increasing the pressure to 2.5-5.0 MPa, ending the reaction, cooling the inner coil by using programmed cooling conduction oil, quickly cooling to 280-300 ℃ within 1-2 hours, then cooling to less than or equal to 150 ℃ within 0.5-1 hour, gradually discharging propylene and ethylene discharged from the reaction, pressurizing the discharged gas by a pressurizing pump, storing the discharged gas in a stainless steel spherical tank, replacing the pyrolysis reaction condensate with nitrogen for 0.5 hour slightly after the gas discharge, and filtering to obtain a pyrolysis reaction product, wherein the solid catalyst is used mechanically;

step two, the synthesis of 2-isopropyl-5-cresol and 4-isopropyl-3-cresol and/or o/p-isopropyl phenol and/or ethyl phenol comprises the following steps:

2.1, thymol and o-isopropyl phenol are synthesized;

2.1.1 Synthesis of thymol:

Adding m-cresol, an acid catalyst and a polymerization inhibitor into another stainless steel pressure kettle while carrying out cracking and transposition reaction in the first step, starting stirring, heating to 160-170 ℃, synchronously and slowly decompressing olefin stored in a spherical tank and discharged after cooling in the first step, introducing the olefin into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 170-200 ℃, and repeatedly introducing the olefin to the kettle pressure for a plurality of times to maintain 2.3-2.5 MPa; discharging unreacted ethylene in the kettle when the pressure of the spherical kettle is reduced to 2.6MPa, continuously and repeatedly introducing olefin in the spherical kettle to react to the pressure of 1.3-1.5 MPa in the kettle, discharging unreacted ethylene when the pressure of the spherical kettle is reduced to 1.6MPa, repeatedly introducing olefin to react to 0.6MPa in the kettle when the pressure of the spherical kettle is reduced to 0.7MPa, discharging unreacted ethylene when the pressure of the kettle is not reduced, introducing olefin to react to 0.1MPa in the kettle, introducing olefin to react to the spherical kettle to react to the unreacted ethylene when the pressure of the spherical kettle is reduced to 0.1MPa, discharging unreacted ethylene when the pressure of the kettle is not reduced, continuously introducing olefin to react to the spherical kettle to the end of 0.03MPa, introducing olefin for 3-12 hours, introducing the olefin to react to heat for 1-4 hours, collecting 160.7 parts of unreacted ethylene, pressurizing and storing the ethylene in the spherical kettle (about 5 MPa) by a pressurizing pump, adding 10-35% of alkali solution to the material in the kettle to 10-35% of a pH value of the kettle at 1-90 ℃ for 10-0.090% of isopropyl cresol, and sequentially cooling the material to the spherical kettle to the distilled water layer at a reflux ratio of 10-99-0.0920% and the isopropyl cresol to the material layer at a reflux ratio of 0-99-10% to 3-20% of the material, and then sequentially carrying out the reflux ratio of the isopropyl cresol to the isopropyl phenol to the material;

2.1.2 Synthesis of O-isopropyl phenol:

Adding phenol, an acid catalyst and a polymerization inhibitor into another stainless steel pressure kettle during the first cracking reaction and the transposition reaction, starting stirring, heating to 160-170 ℃, synchronously and slowly depressurizing the olefin stored in a spherical tank discharged after the first cracking reaction is cooled, introducing the olefin into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 170-200 ℃, repeatedly introducing the olefin to the kettle for maintaining the pressure at 2.3-2.5 MPa, discharging unreacted ethylene in the kettle when the pressure of the spherical tank is reduced to 2.6MPa, continuously repeatedly introducing the olefin in the spherical tank to the pressure of 1.3-1.5 MPa, discharging unreacted ethylene when the pressure of the spherical tank is not reduced any more, repeatedly introducing the olefin to the spherical tank to the pressure of 0.6MPa, repeatedly introducing the olefin to the spherical tank to the pressure of 0.7MPa, repeatedly introducing the olefin to the spherical tank to the pressure of 0.1MPa, introducing the olefin to the spherical tank to the pressure of 0.03-95%, continuously introducing the olefin to the spherical tank to the pressure of 0.95-99-95%, continuously introducing the olefin to the spherical tank to the pressure of 0.3-95%, continuously introducing the olefin to the spherical tank to the pressure of 0.95-99-10% and continuously introducing the isopropyl-1.95% of the isopropyl-phase, and continuously introducing the unreacted ethylene into the spherical tank to the pressure of 0-95-10-0-95% to obtain the crude product, and continuously introducing the isopropyl-phase, and continuously introducing the isopropyl-phenol, and carrying out the isopropyl-phase, and the crude-phenol, at the three-phase, and the three-phase kettle;

Adding crude p-isopropyl phenol and petroleum ether at 90-120 ℃ into a reactor, starting stirring, heating to 70-90 ℃ to enable materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 2-3 hours, cooling to 0-20 ℃ with chilled brine for 2-4 hours, preserving heat for 1-3 hours, filtering, pumping, and drying to obtain p-isopropyl phenol with the concentration of more than or equal to 99%;

2.1.3 Synthesis of thymol, p-isopropyl phenol:

Adding m-cresol, phenol, an acid catalyst and a polymerization inhibitor into another stainless steel pressure kettle while carrying out cracking and transposition reaction in the first step, starting stirring, heating to 160-170 ℃, synchronously and slowly depressurizing the olefin stored in a spherical tank after cooling in the first step, introducing the olefin into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 170-200 ℃, and repeatedly introducing the olefin until the pressure in the kettle is kept at 2.3-2.5 MPa; discharging unreacted ethylene in the kettle when the pressure of the spherical kettle is reduced to 2.6MPa, then continuously and repeatedly introducing olefin in the spherical kettle to react to the pressure of 1.3-1.5 MPa in the kettle, discharging unreacted ethylene when the pressure of the spherical kettle is reduced to 1.6MPa, repeatedly introducing olefin to react to 0.6MPa in the kettle, discharging unreacted ethylene when the pressure of the spherical kettle is reduced to 0.7MPa, introducing olefin to react to 0.1MPa in the kettle, introducing olefin to react to the pressure of 0.03MPa in the spherical kettle, discharging unreacted ethylene when the pressure of the spherical kettle is reduced to 0.1MPa, introducing olefin to react to the end of 0.03MPa, introducing olefin to react for 2 hours after heat preservation, collecting unreacted ethylene, pressurizing and storing the unreacted ethylene in the spherical kettle by a pressurizing pump, cooling the pressure kettle to 90 ℃ for 1-3 hours, adding 10-35% liquid alkali to pH 7-8 in the kettle, adding phenol to the kettle, and carrying out a reflux ratio of isopropyl phenol to the distilled kettle to be 0.095-99% in turn, and obtaining the isopropyl phenol to the distilled phenol to be distilled water to be in the distilled kettle, wherein the reflux ratio of the isopropyl phenol to the distilled phenol to be 0-99-99.095% is not less than 0%;

2.2 Synthesis of para-ethylphenol:

Adding phenol and an acidic catalyst into a stainless steel pressure kettle while synthesizing thymol and the like, stirring, heating to 210-250 ℃, slowly decompressing the pressurized ethylene collected in an ethylene spherical tank in the second step 2.1, introducing the pressurized ethylene into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 220-250 ℃, reacting at 0.9-1.0 MPa, introducing olefin for 4-10 hours, stopping ventilation when the pressure on the spherical tank is reduced to 1.0MPa, keeping the pressure kettle for 1-4 hours, stopping reaction when the kettle pressure is stable and does not reduce, cooling the pressure kettle to less than or equal to 90 ℃ for 1-3 hours, adding 10-35% of liquid alkali into materials in the kettle for neutralizing to PH 7-8, separating a salt water layer, adding the material layer into a rectifying tower kettle, applying the material layer at-0.085 to-0.095 MPa, and obtaining unreacted phenol through rectification, and then sequentially obtaining 99% o-ethylphenol and more than or equal to 95% crude p-ethylphenol;

Adding crude p-ethyl phenol and methanol into a reactor, starting stirring, heating to 60-70 ℃ to enable materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 2-3 hours, cooling to 0-10 ℃ with chilled brine for 2-4 hours, preserving heat for 1-3 hours, filtering, pumping, and drying to obtain p-ethyl phenol with the concentration of more than or equal to 99%;

step three, rectifying and separating a cracking product:

Adding the cracking reaction product obtained in the step one into a tower kettle of a rectifying tower, and rectifying under reduced pressure to obtain 99% of phenol, 99% of mixed cresol, more than or equal to 98% of 2, 5-xylenol/2, 4-xylenol (the ratio of 2, 5-xylenol/2, 4-xylenol is more than or equal to 98%), the ratio of 2, 5-xylenol is more than or equal to 70%), the mixed xylenol, more than or equal to 90% of crude 3, 5-xylenol and more than or equal to 90% of crude 3, 4-xylenol;

99% of mixed cresol can be used for rectifying 99.5% of o-cresol and more than or equal to 98% of m-cresol and p-cresol products;

More than or equal to 98 percent of 2, 5-xylenol/2, 4-xylenol can be used for producing 6-tert-butyl-2, 4-xylenol and 4-tert-butyl-2, 5-xylenol products by tert-butyl separation, and can also be used for producing 2, 5-xylenol by a solvent crystallization method, and pure 3, 5-xylenol and 3, 4-xylenol can be produced by a solvent crystallization or melt crystallization method from crude 3, 5-xylenol and crude 3, 4-xylenol;

the mixed xylenols can be used for alkylation separation to produce 2, 4-xylenol, 2, 5-xylenol, 2, 3-xylenol, m-ethylphenol, p-ethylphenol and the like;

step four, refining a cracking rectification crude product:

4.1 adding the crude product of the step III 3, 5-xylenol and the solvent into a reactor, starting stirring, heating to 60-90 ℃ to enable the materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 1-3 hours, cooling to 0-20 ℃ with chilled brine for 1-3 hours, preserving heat for 1-2 hours, filtering, pumping, drying to obtain 3, 5-xylenol with concentration of more than or equal to 99%;

4.2 adding the crude product of the step III 3, 4-xylenol and the solvent into a reactor, starting stirring, heating to 60-90 ℃ to enable the materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 1-3 hours, cooling to 0-20 ℃ with chilled brine for 1-3 hours, preserving heat for 1-2 hours, filtering, pumping, drying to obtain 3, 4-xylenol with concentration of more than or equal to 99%;

4.3 adding 500 parts of step three 2, 5-xylenol/2, 4-xylenol and a solvent into a reactor, starting stirring, heating to 60-90 ℃ to completely dissolve materials, then cooling to 30-40 ℃ with circulating water for 1-3 hours, cooling to 0-20 ℃ with chilled brine for 1-3 hours, preserving heat for 1-2 hours, filtering, pumping, and drying to obtain 2, 5-xylenol with concentration of more than or equal to 99%;

step five, alkylating and separating the mixed xylenol obtained by cracking and rectifying:

5.1 octylating and separating, namely adding the mixed xylenol and diisobutylene obtained in the step three into a pressure reaction kettle, adding an acid catalyst, stirring and heating to 100-150 ℃ for reaction, wherein the reaction time is 2-12 hours, sampling and analyzing that 2, 3-xylenol is less than or equal to 0.5 percent and is qualified, filtering, rectifying filtrate to recover diisobutylene, then sequentially obtaining more than or equal to 95 percent of 2, 5-xylenol, 99 percent of 3, 5-xylenol, 99 percent of antioxidant, and 99 percent of 6-isooctyl-2, 4-xylenol, and obtaining more than or equal to 95 percent of 6-isooctyl-2, 3-xylenol, wherein the kettle residue mainly contains part of 6-isooctyl m-ethylphenol, 2, 6-diisooctyl p-ethylphenol and the like;

Adding more than or equal to 95% of 6-isooctyl-2, 3-xylenol into a decomposing kettle, stirring, adding more than or equal to 95% of sulfuric acid, heating to 180-200 ℃ for 0.5-2 hours, sampling and analyzing that the 6-isooctyl-2, 3-xylenol is less than or equal to 0.5% and is qualified, cooling to 70-90 ℃ after the 6-isooctyl-2, 3-xylenol is qualified, adding 10-35% of sodium hydroxide aqueous solution to neutralize to PH 7-7.5, rectifying under normal pressure to obtain diisobutylene for reuse, and then rectifying under reduced pressure to obtain 99% of 2, 3-xylenol;

Adding more than or equal to 95% of 2, 5-xylenol and methanol into a crystallization reactor, starting stirring, heating to 60-70 ℃ to enable materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 1-3 hours, cooling to 0-20 ℃ with chilled brine for 1-3 hours, preserving heat for 1-2 hours, filtering, pumping, and drying to obtain more than or equal to 99% of 2, 5-xylenol;

5.2 isohexide separation, adding the mixed xylenol and 6-isohexyl-2, 4-xylenol obtained in the step three into an autoclave, adding strong acid resin, stirring and heating to 100-150 ℃ for reaction, introducing vaporized isohexide to the pressure of the autoclave at 0.6MPa, introducing vaporized isohexide to 0.6MPa again when the pressure in the autoclave is reduced to 0.1MPa, reacting for multiple times, sampling and analyzing that the 2, 3-xylenol is less than or equal to 0.5 percent and is qualified when the pressure in the autoclave is reduced slowly, reacting for 4-12 hours, cooling to 70-90 ℃, filtering, decompressing and rectifying filtrate to obtain not less than 98 percent of 2, 5-xylenol and not less than 99 percent of 3, 5-xylenol, obtaining 99 percent of 6-isohexyl-2, 4-xylenol, and obtaining 95 percent of 6-isohexyl-2, 3-xylenol;

Adding 6-isohexyl-2, 3-xylenol into a decomposing kettle, stirring, adding sulfuric acid, heating to 180-200 ℃, reacting for 0.5-3 hours at a temperature of heat preservation, removing isohexide, and rectifying to obtain 99%2, 3-xylenol, wherein isohexide is used mechanically;

adding less than or equal to 99% of 2, 5-xylenol and methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 30-40 ℃ with circulating water for 2-4 hours, cooling to-10 ℃ with chilled brine for 2-4 hours, preserving heat for 1-3 hours, filtering, pumping, and drying to obtain 99.5% of 2, 5-xylenol;

Step six, 2, 5-xylenol/2, 4-xylenol alkylation separation:

Adding more than or equal to 98% of 2, 5-xylenol/2, 4-xylenol and 6-isononyl-2, 4-xylenol obtained in the step three into an autoclave, adding strong acid resin, stirring and heating to 100-180 ℃, dropwise adding isononane for reaction for 4-12 hours, dropwise finishing the heat preservation reaction for 1-4 hours, sampling and analyzing that the 2, 4-xylenol is less than or equal to 0.3% and qualified, reducing the temperature to 70-100 ℃ after the completion of the reaction, filtering, decompressing and rectifying filtrate (-0.09 to-0.1 MPa, and obtaining the 2, 5-xylenol with the concentration of more than or equal to 99.5% and the antioxidant 6-isononyl-2, 4-xylenol with the reflux ratio of 10-30:1) with the concentration of more than or equal to 99%.

Preferably, in the first step, a2, 4-xylenol/2, 5-xylenol mixture is added, wherein the 2, 4-xylenol/2, 5-xylenol mixture contains 0.5-2:1, 2,4/2, 5-xylenol 50-97%, preferably 70-90% of 2, 4-xylenol/2, 5-xylenol, and the 2, 4-xylenol/2, 5-xylenol mixture contains 1-30%, preferably 5-20% of ortho-isopropyl phenol/ortho-propyl phenol, and 0-30%, preferably 1-20% of 2-ethyl-6-cresol.

Preferably, in the first step, an acidic silicon aluminum chromium oxide solid catalyst is filled in a stainless steel high-pressure reactor (with an external stainless steel condenser and an internal coil), wherein the silicon aluminum chromium oxide is silicon dioxide, acidic aluminum oxide and chromium oxide, the mass ratio of the silicon dioxide to the acidic aluminum oxide is 0.1-10:10-0.1, preferably 0.2-5:5-0.2, the chromium oxide is 0.01-0.2 of the mass of the silicon dioxide, and the silicon aluminum chromium oxide is 5-30% of the weight of the 2,4/2, 5-xylenol mixture.

Preferably, in the first step, the temperature of the heat conduction oil is gradually and slowly reduced to 80 ℃ from a high temperature, and the Gao Wenwei is 50-100 ℃ lower than the temperature of the cracking and transposition reaction.

Preferably, in the first step, the mixed phenol composed of cleavage reaction products [2, 5-xylenol/2, 4-xylenol (mainly 2, 5-xylenol), other xylenols (mainly 3, 5-xylenol), partial phenols (mainly m-cresol) and the like ] is obtained by filtering, wherein the cresol is a mixture composed of m-cresol, p-cresol, o-ethylphenol and the like, the m-cresol is mainly, 2, 4-xylenol in the 2, 4-xylenol/2, 5-xylenol is 1:2-5, the other xylenols are 3, 5-xylenol, 2, 3-xylenol, 3, 4-xylenol, a small amount of m-p-ethylphenol and the like, and the 3, 5-xylenol is mainly.

Preferably, in the second step 2.1, the acid catalyst is at least one of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, benzenesulfonic acid, solid acid catalyst, acid resin, zirconia, acid alumina, silica and the like, preferably mixed acid of sulfuric acid and phosphoric acid, and the amount of the mixed acid is 0.5-5% of the mass of m-cresol or phenol or the mixture of m-cresol and phenol, wherein the mass ratio of sulfuric acid to phosphoric acid is 5-7:5-3.

Preferably, the acid catalyst in the second step 2.2 is at least one of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, benzenesulfonic acid, solid acid catalyst, acid resin, zirconia, acid alumina, silica and the like, preferably mixed acid of sulfuric acid and phosphoric acid, wherein the amount of the mixed acid is 1-5% of the mass of phenol, and the mass ratio of sulfuric acid to phosphoric acid is 9-7:1-3.

Preferably, the polymerization inhibitor in the step II 2.1 is hydroquinone, 2-methyl hydroquinone, 2-tertiary butyl hydroquinone, 6-tertiary butyl-2, 4-xylenol, p-methoxyphenol and the like, preferably 2-methyl hydroquinone.

Preferably, in the second step 2.1.3, m-cresol and phenol are added into another stainless steel autoclave, wherein the mass ratio of the m-cresol to the phenol is 1:0.5-2.

Preferably, in the third step, xylenol is mixed, wherein the mixed xylenol consists of two or more of 2, 4-xylenol, 2, 5-xylenol, 2, 3-xylenol, 3, 5-xylenol, a small amount of m-para-ethylphenol and the like, and the content of 2, 3-xylenol is mainly not less than 50%.

Preferably, the solvent in the fourth step 4.1, 4.2 and 4.3 is alcohols (methanol, ethanol, etc.), alkanes (including petroleum ether), ethers, esters, ketones, etc., preferably methanol and petroleum ether.

Preferably, in the fifth step, an acidic catalyst is added, wherein the acidic catalyst is an inorganic acid such as sulfuric acid or phosphoric acid, an organic acid such as sulfamic acid, benzenesulfonic acid or toluenesulfonic acid, a solid acid such as antimonic acid, a strongly acidic resin, etc., preferably a strongly acidic resin.

The beneficial effects are that:

1. The invention removes the ethyl in the 2-ethyl-6-cresol in the alkylphenol and the isopropyl/propyl in the o-isopropyl phenol/o-propyl phenol at high temperature to obtain the purified 2,5/2, 4-xylenol product, and produces the high-purity product.

2. The invention removes isopropyl/propyl in alkylphenol at high temperature, then selectively reacts excessive m-cresol with isopropyl under the catalysis of acidic substances, and rectifies to obtain 2-isopropyl-5-cresol and 4-isopropyl-3-cresol products, and byproducts of petrochemical interstage cresol.

3. The invention removes isopropyl/propyl in alkylphenol at high temperature, then selectively reacts excessive phenol with isopropyl under the catalysis of acidic substances, rectifies to obtain petrochemical-grade o-isopropyl phenol and p-isopropyl phenol products, and byproducts of petrochemical-grade phenol products.

4. According to the invention, ethyl in alkylphenol is removed at high temperature, then excess phenol is selectively reacted with ethyl under the catalysis of acidic substances, petrochemical-grade o-ethylphenol and p-ethylphenol products are obtained through rectification, and petrochemical-grade phenol products are produced as byproducts.

5. The invention realizes the transfer of other cresols to m-cresol, other xylenols to 3, 5-xylenol, 2, 5-xylenol and other ethylphenols to m-ethylphenol by the high-temperature removal of alkyl groups in alkylphenol and the medium-low-temperature alkyl transposition reaction, and the market value of m-cresol, m-ethylphenol, 3, 5-xylenol and the like is obviously higher than that of o-cresol, p-cresol, 2, 4-xylenol and o-ethylphenol after dealkylation and before transposition, thus greatly improving the value of phenol products.

6. The 2,5/2, 4-xylenol mixture is alkylated with isononane to obtain high-purity 2, 5-xylenol, high-efficiency polymerization inhibitor and antioxidant 6-isononyl-2, 4-xylenol, and meanwhile, the separation of 2,5/2, 4-xylenol can be effectively carried out.

7. The invention can also separate and mix xylenol with diisobutylene, isohexene and the like by a xylenol alkylation method, and byproducts such as 3, 5-xylenol, 3, 4-xylenol, 2, 3-xylenol and the like are produced.

8. The method is particularly suitable for separating the 2,4/2, 5-xylenol mixture with high content of o-isopropyl phenol/o-propyl phenol and 2-ethyl-6-cresol, which is obtained by refining the crude phenol, by a medium-low temperature phenol-containing coal tar solvent method, and the method is not found in relevant documents and patent reports, belongs to a brand new research topic, and has good economic and social benefits.

Detailed Description

Example 1

A process for preparing phenol products from 2, 4-xylenol/2, 5-xylenol includes such steps as cracking and transposition reaction

Charging 750 parts of an acidic silicon aluminum chromium oxide solid catalyst (silicon aluminum chromium ratio is 1:2:0.2) and 50 parts of zirconium phosphate into a stainless steel high-pressure reactor with an external stainless steel condenser and an internal coil, adding 5000 parts of a2, 4-xylenol/2, 5-xylenol mixture (15 parts of m-cresol and 1875 parts of 2, 5-xylenol are contained in the mixture), sealing, heating to 340 ℃ for reaction for 4 hours, gradually increasing the pressure to 3.8-3.9 MPa, cooling the temperature of the heat conducting oil in the internal coil to 280 ℃ by using a programmed cooling process (the temperature of the heat conducting oil is gradually reduced to 80 ℃ from high temperature), gradually discharging propylene and ethylene discharged from the reaction in a step by step in 40 minutes, storing the discharged gas in a non-steel pressure tank by using a pressurizing pump (750 parts of o-isopropyl phenol/o-propyl phenol), and then adding 3.3-xylenol into 3.9 parts of 3-xylenol, 3-ethyl-3-xylenol, 3-63 parts of the mixture, and obtaining 3-xylenol condensate (3.37 parts of zirconium phosphate), and obtaining 3.3-3.9 parts of zirconium phosphate as a catalyst by using 3.37 parts of zirconium oxide solid oxide, 3-3:3:9:3:9 after the zirconium phosphate is completely reacted, wherein the 3:3:3:3:9:3:9:9:3:9:3 by using programmed cooling of heat conducting oil in the internal coil;

Step two, synthesis of 2-isopropyl-5-cresol and 4-isopropyl-3-cresol and ethylphenol

2.1 Synthesis of thymol and the like

During the first cracking and transposition reaction, 953 parts of m-cresol and 30 parts of sulfuric acid/phosphoric acid mixed acid (m-cresol is 1.6 times of the molar mass of o-isopropyl/propylphenol) are added into another stainless steel pressure kettle, stirring is started, the temperature is raised to 180 ℃, the olefin stored in a spherical tank and discharged after the first cracking reaction is cooled is synchronously and slowly depressurized and introduced into the stainless steel pressure kettle for reaction, the temperature of the kettle is kept at 180-190 ℃ for reaction, the olefin is reacted to 2.3-2.5 MPa, the pressure of the spherical tank is reduced to 2.6MPa, unreacted ethylene is discharged when the pressure of the pressure kettle is not reduced any more, then the olefin is reacted to 1.3-1.5 MPa, the pressure of the spherical tank is reduced to 1.6MPa, unreacted ethylene is discharged when the pressure of the pressure kettle is not reduced any more, the pressure of the spherical tank is reduced to 0.6MPa, the pressure of the spherical tank is reduced to 0.7MPa, the ethylene is not reduced to the pressure of the spherical tank, the ethylene is discharged when the pressure of the spherical tank is not reduced to the 0.5 MPa, the total pressure of the spherical tank is reduced to about 20.5-5 MPa, the total pressure of the spherical tank is continuously added to the spherical tank is discharged to the total pressure of 0.0.0.0-5%, the reflux liquid is discharged to the spherical tank is discharged to the total pressure of about 20.5% after the spherical tank, the reflux is reduced to the total pressure of the spherical tank is equal to about 20.5%, the total pressure of the spherical tank is discharged to the total pressure is equal to 5.5%, the total pressure of the unreacted ethylene is discharged to 20.5%, the total pressure is discharged to the required to 5, the reflux ratio is discharged to the spherical tank is discharged to the total pressure is at the pressure of 0.0.0.0% and the required to 5, and the pressure is discharged after the pressure is discharged from the required pressure and the pressure and is discharged from the required, 279.9 parts of 99.6% high-efficiency bactericide 4-isopropyl-3-cresol;

2.2 Synthesis of Parafresh phenol and the like

Adding 800 parts of phenol and 25 parts of sulfuric acid/phosphoric acid (phenol is 1.26 times of the molar mass of 2-ethyl-6-cresol, 98% sulfuric acid: 85% phosphoric acid mass ratio is 8-9:2-1) into a stainless steel pressure kettle while synthesizing thymol, starting stirring, heating to 240 ℃, slowly decompressing and introducing pressurized ethylene collected in a vinyl spherical tank in the step two 2.1 into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 230-240 ℃, reacting at 0.9-1.0 MPa, introducing olefin for 6 hours, stopping ventilation when the pressure on the spherical tank is reduced to 1.3MPa, keeping the pressure kettle at the temperature for 3 hours, stopping reacting when the kettle pressure is reduced to 0.6MPa or the kettle pressure is not reduced, adding 30% of liquid alkali into materials in the kettle to 70 parts and to PH7.5, separating a brine layer, adding a material layer into a rectifying tower kettle (theoretical plate number 200), rectifying at-0.09 MPa, refluxing for 10-15 to obtain unreacted phenol 391.8 parts, and then sequentially obtaining 99.6% of o-ethyl phenol, 8.37% of crude ethyl phenol and 3.308 parts of other crude ethyl phenol (3.3.308 parts of ethyl phenol);

Adding 319.8 parts of 96.37% crude p-ethyl phenol and 300 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 35 ℃ in a cold water bath for 2 hours, cooling to 0 ℃ in an ice water bath for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 292.4 parts of 99.71% p-ethyl phenol, and refining yield is 94.6%;

step three, rectifying and separating the cracked product

Adding 4506.9 parts of the cracking reaction product obtained in the step one into a rectifying tower kettle (100 parts of dimethyl diphenyl ether high-boiling point solvent is added into the tower kettle), rectifying under reduced pressure (the vacuum degree is-0.088 MPa, the reflux ratio is 15-25:1), obtaining 99.23 percent phenol 457.5 parts, 99.1 percent cresol 647.1 parts (ortho-cresol 232.9 parts, para-cresol 116.7 parts, meta-cresol 291.8 parts, ortho-ethylphenol 3.1 parts), 98.73 percent 2,4/2, 5-xylenol 2141.8 parts (2, 4-xylenol 409.6 parts, 2, 5-xylenol 1705.1 parts, meta-cresol 9.8 parts, 2, 3-xylenol 15.2 parts and other 2.1 parts), 2, 5-xylenol 79.61%), mixed xylenol 209.2 parts (2, 4-xylenol 12.4 parts, 2, 5-xylenol 41.3 parts, 2, 3-xylenol 139.2 parts, 3, 5-xylenol 12.3 parts, m-p-ethylphenol 4 parts, 2, 3-xylenol 66.54%), 96.4% crude 3, 5-xylenol 638.7 parts (2, 3-xylenol 6.5 parts, 3, 5-xylenol 615.8 parts, 3, 4-xylenol 14.6 parts, m-p-ethylphenol 1.8 parts), 93.61% crude 3, 4-xylenol 216.1 parts (2, 3-xylenol 1.1 parts, 3, 5-xylenol 10.2 parts, 3, 4-xylenol 202.3 parts);

99.1% cresol 647.1 parts (232.8 parts of o-cresol, 116.7 parts of p-cresol, 291.8 parts of m-cresol, 3.2 parts of o-ethylphenol) can be used for rectifying 99.5% o-cresol, 99% m-p-cresol products;

98.73% of 2,4/2, 5-xylenol (2, 5-xylenol content 79.61%) can be used for t-butyl separation to produce 6-t-butyl-2, 4-xylenol and 4-t-butyl-2, 5-xylenol products, and can also be used for producing 2, 5-xylenol by a solvent crystallization method, 96.4% of 3, 5-xylenol crude products and 93.61% of 3, 4-xylenol crude products can be used for producing pure 3, 5-xylenol and 3, 4-xylenol by a solvent crystallization or melt crystallization method;

209.2 parts of mixed xylenol (12.4 parts of 2, 4-xylenol, 41.3 parts of 2, 5-xylenol, 139.2 parts of 2, 3-xylenol, 12.3 parts of 3, 5-xylenol, 4 parts of m-p-ethylphenol, 66.54% of 2, 3-xylenol) can be used for alkylation separation to produce 2, 4-xylenol, 2, 5-xylenol, 2.3-xylenol, m-ethylphenol, p-ethylphenol and the like;

Step four, refining the crude product obtained by cracking and rectifying

Adding 638.7 parts of a step III 96.4%3, 5-xylenol crude product and 500 parts of methanol into a reactor, starting stirring, heating to 60 ℃ to completely dissolve materials, then cooling to 35 ℃ with circulating water for 2 hours, cooling to 0 ℃ with chilled brine for 2 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 584.7 parts of 99.82%3, 5-xylenol, and refining the product with a yield of 94.8%;

Adding 216.1 parts of the crude 3, 4-xylenol product with 93.61 percent and 600 parts of petroleum ether with 90-120 ℃ in a reactor, starting stirring, heating to 70 ℃ to completely dissolve materials, then cooling to 33 ℃ by using circulating water for 2.5 hours, cooling to 20 ℃ by using chilled brine for 2 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 178.2 parts of 3, 4-xylenol with 99.64 percent, and refining yield of 87.8 percent;

4.3 adding 500 parts of 98.73 percent 2,4/2, 5-xylenol (2, 5-xylenol 79.61%) and 300 parts of methanol into a reactor, starting stirring, heating to 60 ℃ to completely dissolve materials, then cooling to 35 ℃ by using circulating water for 2 hours, cooling to-10 ℃ by using chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 261.5 parts of 99.85 percent 2, 5-xylenol, and refining the product with a yield of 65.6 percent;

Step five, mixed xylenol obtained by cracking and rectifying is separated in an octyl mode

Adding 209.2 parts of mixed xylenol (12.4 parts of 2, 4-xylenol, 41.3 parts of 2, 3-xylenol, 139.2 parts of 3, 5-xylenol, 12.3 parts of m-p-ethylphenol) and 600 parts of diisobutylene obtained in the step three into a reaction kettle, adding 100 parts of strong acid resin, stirring and heating to 110 ℃ for reaction, reacting for 10 hours, sampling and analyzing 0.01% of 4-isooctyl-p-ethylphenol to be qualified, filtering, rectifying the filtrate and recovering 435 parts of diisobutylene for reuse, and then decompressing and rectifying (-0.095 MPa, reflux ratio 25-30:1) to sequentially obtain 98.32% of 2, 5-xylenol 38.2 parts, 99.13% of 3, 5-xylenol 10.3 parts, yield of 90.9%, 83.2% of antioxidant 99.23% of 6-isooctyl-2, 4-xylenol 19.5 parts, yield of 81.2%, obtaining 97.35% of 6-isooctyl-2, 3-xylenol 207.9% of residual 2.8%, and 75% of diisooctyl-2, 4-ethyl-2-xylenol;

Adding 207.9 parts of 97.35% 6-isooctyl-2, 3-xylenol into a decomposing kettle, stirring, adding 5 parts of sulfuric acid, heating to 200 ℃ for 1.5 hours, and rectifying to obtain 103.3 parts of 99.38%2, 3-xylenol with a yield of 94.7%) (dimethyl diphenyl ether with a high boiling point is added into the rectifying tower kettle in advance);

Adding 38.2 parts of 98.32%2, 5-xylenol and 24 parts of methanol into a reactor, starting stirring, heating to 60 ℃ to completely dissolve materials, then cooling to 35 ℃ by using a cold water bath, cooling to-10 ℃ by using an ice water bath, preserving heat for 2 hours, filtering, pumping, drying to obtain 36.2 parts of 99.53%2, 5-xylenol, and refining the materials to obtain the refined yield of 95.9%;

Step six, alkylation separation of 2,5/2, 4-xylenol (2, 5-xylenol crude product)

Adding 1000 parts of 98.73%2,4/2, 5-xylenol (191.2 parts of 2, 5-xylenol, 796.1 parts of 2, 5-xylenol, 4.6 parts of m-p-cresol, 7.1 parts of 2, 3-xylenol and 1 part of the other) obtained in the step three into a pressure kettle, adding 200 parts of strong acid resin, stirring and heating to 120 ℃, dropwise adding isononane for 6 hours, dropwise adding, sealing the equipment, heating to 160 ℃ for 1 hour, sampling and analyzing 0.11% of 2, 4-xylenol, 241 parts of isononane (1.22 times of the molar amount of 2, 4-xylenol in 2,5/2, 4-xylenol), cooling to 90 ℃ for filtering, decompressing and rectifying filtrate (-0.098 MPa, reflux ratio of 20-25:1), and obtaining 99.5% of 2, 5-xylenol with 756.9 parts, 94.6% of the yield and 99.6% of the antioxidant, and 99.9% of the antioxidant, 4-9% of the 2, 4-xylenol.

Example 2

Step one, cleavage reaction

Filling 1000 parts of an acidic silicon-aluminum-chromium oxide solid catalyst (silicon-aluminum-chromium ratio is 1:2:0.1) and 30 parts of zirconium phosphate into a stainless steel high-pressure reactor with an external stainless steel condenser and an internal coil, adding 4908 parts of a 2, 4-xylenol/2, 5-xylenol mixture (comprising 2361.6 parts of 2, 4-xylenol, 1586.4 parts of 2, 5-xylenol and 960 parts of o-isopropyl phenol) into the reactor, sealing, heating to 300 ℃ for reaction for 6 hours, gradually increasing the pressure to 2.8-2.9 MPa, ending the reaction, rapidly reducing the temperature of the heat conducting oil in the internal coil by using a program (gradually and slowly reducing the temperature of the heat conducting oil from high temperature to 80 ℃), discharging propylene which is removed after the reaction when the temperature of the material is reduced to 150 ℃, and pressurizing the discharged gas by a pressurizing pump and storing the discharged gas in a stainless steel spherical tank (about 5 MPa); after the gas was exhausted, the reaction mixture was slightly cooled and replaced with nitrogen for 0.5 hour, and the reaction mixture was filtered to give 4606 parts of cleavage reaction products (15.2 parts of o-isopropyl phenol, 23.2 parts of m-p-isopropyl phenol, 624.4 parts of phenol, 628 parts of 2, 4-xylenol, 2431.2 parts of 2, 5-xylenol, 578.4 parts of 3, 5-xylenol, 138.4 parts of 3, 4-xylenol, 92.8 parts of 2, 3-xylenol, and 74.4 parts of others);

step two, synthesis of o-isopropyl phenol and p-isopropyl phenol

Adding 1525 parts of phenol and 50 parts of 98% sulfuric acid (phenol is 2 times of the molar mass of the o-isopropyl/propyl phenol) into a stainless steel pressure kettle, starting stirring, heating to 160 ℃, synchronously introducing propylene which is discharged after the temperature reduction of the cracking reaction in the step one and stored in a stainless steel spherical tank into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 160-170 ℃ for reaction, keeping the pressure at 0.8-0.9 MPa, introducing propylene for 5 hours, and keeping the temperature for reaction for 3 hours, adding 133.5 parts of 30% liquid alkali into materials in the kettle for neutralization until the PH is 7.0, separating a salt water layer, adding a material layer into a rectifying tower kettle (theoretical plate number of 200), obtaining 871.6 parts of unreacted phenol at-0.09 MPa with reflux ratio of 15-20, and then sequentially obtaining 537.6 parts of 99.1% o-isopropyl phenol, 336.2 parts of 96.6% crude p-isopropyl phenol (325.8 parts of p-isopropyl phenol and 10.4 parts of m-isopropyl phenol);

Adding 336.2 parts of 96.6% crude p-isopropyl phenol and 1000 parts of 90-120 ℃ petroleum ether into a reactor, starting stirring, heating to 70 ℃ to completely dissolve materials, then cooling in a cold water bath for 3 hours to 35 ℃ and then cooling in an ice water bath for 3 hours to 20 ℃, preserving heat for 1 hour, filtering, pumping, drying to obtain 304.5 parts of 99.7% p-isopropyl phenol, and refining the product with the yield of 93.2%;

Step three, rectifying the cracking reaction product

Adding 4606 parts of the cracking reaction product obtained in the step one into a rectifying tower kettle (100 parts of dimethyl diphenyl ether high-boiling point solvent is added into the tower kettle), carrying out reduced pressure rectification (vacuum degree-0.088 MPa, reflux ratio is 10-30:1), obtaining 591.6 parts of 99.5% phenol, 2928.4 parts of 99.36%2,5/2, 4-xylenol (2, 4-xylenol 595.2 parts, 2314.4 parts of 2, 5-xylenol, 10 parts of o-isopropyl phenol, 79.03 parts of 2, 5-xylenol), 122.4 parts of mixed xylenol (5.2 parts of 2, 5-xylenol, 21.2 parts of 2, 3-xylenol 80.8 parts, 14.4 parts of 3, 5-xylenol, other 0.8 parts of 2, 3-xylenol 66.01%), 584.4 parts of 93.91%3, 5-xylenol crude product (2, 3-xylenol 9.2 parts of 3, 5-xylenol, 548.8 parts of 3, 4-xylenol, 24.8 parts of 3, 92.7.2 parts of 3, 5-xylenol, 3.8 parts of 3-xylenol, 3.7.8 parts of 3, 6.8 parts of 3-xylenol, 3-xylenol, 3.8 parts of 3.6 parts of 3-xylenol, 3.8 parts of 3, 6.8 parts of 3-m-propyl phenol, 3, 3.8 parts of 3, 4-xylenol;

99.36% of 2,5/2, 4-xylenol can be separated by tertiary butyl to produce 6-tertiary butyl-2, 4-xylenol and 4-tertiary butyl-2, 5-xylenol products, and can also be used for producing 2, 5-xylenol by solvent crystallization, 93.91% of crude 3, 5-xylenol and 92.93% of crude 3, 4-xylenol can be used for producing pure 3, 5-xylenol and 3, 4-xylenol by solvent crystallization or melt crystallization;

The 87.02% m-p-isopropyl phenol (22.8 parts of m-p-isopropyl phenol, 0.3 part of 3, 4-xylenol and 3.1 parts of other 3.1 parts of m-isopropyl phenol: 1.98:1) can be used as raw materials of wire enamel, flame retardant plasticizer, photoresist and the like, and can also be used for alkylating and separating the m-p-isopropyl phenol;

step four, refining the cracking rectification crude product

Adding 584.4 parts of 93.91%3, 5-xylenol crude product and 500 parts of 90-120 ℃ petroleum ether obtained in the step III into a reactor, starting stirring, heating to 75 ℃ to enable materials to be completely dissolved, then cooling to 40 ℃ by using circulating water for 2.5 hours, cooling to 20 ℃ by using chilled brine for 2 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 497.6 parts of 99.36%3, 5-xylenol, and refining yield of 90.1%;

4.2 adding 118.4 parts of the 92.57%3, 4-xylenol crude product obtained in the step three and 100 parts of 90-120 ℃ petroleum ether into a reactor, starting stirring, heating to 70 ℃ to enable materials to be completely dissolved, then cooling to 35 ℃ by using circulating water for 2.5 hours, cooling to 15 ℃ by using chilled brine for 2 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 97.6 parts of 99.12%3, 4-xylenol, and refining the yield to 88.3%;

4.3 adding 200 parts of 2,5/2, 4-xylenol (2, 5-xylenol 79.03%) and 100 parts of methanol in the step III into a reactor, starting stirring, heating to 60 ℃ to completely dissolve the materials, then cooling to 35 ℃ with circulating water for 2 hours, cooling to-10 ℃ with chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 113 parts of 99.55%2, 5-xylenol, and refining the yield of 71.2%;

Adding 122.4 parts of mixed xylenol obtained in the step three (5.2 parts of 2, 4-xylenol, 21.2 parts of 2, 5-xylenol, 80.8 parts of 2, 3-xylenol, 14.4 parts of 3, 5-xylenol and 0.8 part of other components, 66.01 parts of 2, 3-xylenol) and 400 parts of diisobutylene into a reaction kettle, adding 100 parts of strong acid resin, stirring and heating to 110 ℃ for reaction, reacting for 10 hours, sampling and analyzing 0.05% of 4-isooctyl-4-ethylphenol to be qualified, filtering, rectifying and recovering 322.3 parts of diisobutylene from filtrate, and then decompressing and rectifying (-0.095 MPa, reflux ratio 25-30:1) to obtain 19.2 parts of 98.22%2, 19.2 parts of 5-xylenol, 11.7 parts of 99.33%3, 11.7 parts of 3 parts of antioxidant, 80.3% of 98.22% of 6-isooctyl-2, 3.7% of antioxidant, and obtaining 98.26% of 6-2, 3-9.78% of diisooctyl-2;

adding 120.2 parts of 98.26% 6-isooctyl-2, 3-xylenol into a decomposing kettle, stirring, adding 1.5 parts of sulfuric acid, heating to 190 ℃ for 2 hours, rectifying (-0.09 MPa, reflux ratio 25-30:1) to obtain 62.1 parts of 99.61%2, 3-xylenol, and obtaining 95.3% yield (dimethyl diphenyl ether with high boiling point is added into the rectifying kettle in advance);

Adding 19.2 parts of 98.22%2, 5-xylenol and 15 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 37 ℃ by using cold water bath for 2 hours, cooling to 0 ℃ by using chilled brine for 2 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 17.8 parts of 99.75%2, 5-xylenol, and refining the product with the yield of 94.2%;

step six, alkylating and separating 2, 5-xylenol/2, 4-xylenol (2, 5-xylenol crude product)

Adding 1000 parts of 2, 5-xylenol/2, 4-xylenol (203.3 parts of 2, 4-xylenol, 790.3 parts of 2, 5-xylenol and 3.4 parts of o-isopropyl phenol) and 1 part of 6-isononyl-2, 4-xylenol obtained in the step three into a pressure kettle, adding 200 parts of strong acid resin, stirring and heating to 140 ℃ for reaction, dropwise adding isononane for 6 hours, keeping the dropwise and heat-preserving reaction for 2 hours, sampling and analyzing that the 2, 4-xylenol is 0.07 percent qualified, 250 parts of isononane (1.19 times of the molar weight of the 2, 4-xylenol in the 2,5/2, 4-xylenol), cooling to 90 ℃ after the reaction, filtering, decompressing and rectifying filtrate (-0.098 MPa), wherein the reflux ratio is 10:1), and obtaining 99.6 percent of 2, 5-xylenol with the yield of 95.2 percent and 99.3 percent of antioxidant, namely the 99.3 percent of 6-isononyl-2, 4-xylenol, 539 percent.

Example 3

Step one, cleavage and translocation reactions

Putting 2000 parts of an acidic silicon-aluminum-chromium oxide solid catalyst (silicon-aluminum-chromium ratio is 1:2:0.2) and 200 parts of zirconium phosphate into a stainless steel high-pressure reactor with an external stainless steel condenser and an internal coil, adding 10000 parts of a2, 4/2, 5-xylenol mixture (the medium and low temperature phenol-containing coal tar is extracted and refined, wherein the 2, 4-xylenol mixture contains 4318 parts of 2, 5-xylenol 3635 parts, o-isopropyl phenol/o-propyl phenol 1204 parts, 2-ethyl-6-cresol 521 parts, 2, 3-xylenol 306 parts and other 16 parts), sealing, heating to 280 ℃ for reaction for 10 hours, gradually increasing the pressure to 2.5-2.6 MPa, ending the reaction, gradually reducing the temperature of the internal coil by using programmed heat conduction oil (the temperature of the heat conduction oil is gradually reduced to 80 ℃), gradually reducing the temperature to 250 ℃ from the high temperature within 10 minutes, then gradually reducing the temperature to about 150 ℃ within about 0.5 hour, gradually discharging propylene and ethylene in the reaction, gradually, and adding the discharged pressurized gas into a ball-shaped steel tank to supplement the 3-xylenol mixture to the solid-2, 3-xylenol mixture to the solid catalyst (the rest of 3, 3-xylenol mixture is gradually replaced by the nitrogen and the rest of 3-xylenol mixture), and the solid-containing the solid catalyst (3, 3-xylenol mixture is gradually replaced by 3, 3-xylenol condensate and 3-4.37 parts of 2, 3-xylenol and 3-xylenol is completely replaced by 3-4, 3-4-4:3:3:3:3:3:3:3:3:3:3);

step two, synthesis of 2-isopropyl-5-cresol, 4-isopropyl-3-cresol, ethyl phenol and the like

2.1 Synthesis of thymol and the like

During the first cracking and transposition reaction, 907 parts of 99.3% coking m-cresol (28 ppm of nitride and 19ppm of sulfide), 790 parts of 99% coking phenol (1080 ppm of nitride and 462ppm of sulfide) and 50 parts of sulfuric acid/phosphoric acid mixed acid (the dosage of m-cresol and phenol is 1.9 times of the molar mass of o-isopropyl/propylphenol, the mass ratio of 98% sulfuric acid to 85% phosphoric acid is 7:3) are added into another stainless steel pressure kettle, stirring is started, the temperature is raised to 190 ℃, olefin which is discharged after the first cracking reaction is cooled is synchronously and slowly depressurized and introduced into the stainless steel pressure kettle for reaction, the kettle temperature is kept to be 190-200 ℃, the olefin is introduced for reaction until the pressure in the kettle is 2.3-2.5 MPa, and unreacted ethylene is discharged when the pressure in the spherical kettle is not lowered any more; introducing olefin to the pressure of 1.3-1.5 MPa in the kettle, discharging unreacted ethylene when the pressure of the spherical tank is reduced to 1.6MPa and the pressure of the pressure kettle is not reduced any more, introducing olefin to the pressure of 0.6MPa in the kettle, discharging unreacted ethylene when the pressure of the spherical tank is reduced to 0.7MPa and the pressure of the pressure kettle is not reduced any more, introducing olefin to the pressure of 0.1MPa, discharging unreacted ethylene when the pressure of the spherical tank is reduced to 0.1MPa and the pressure of the pressure kettle is not reduced any more, continuing introducing olefin to the pressure of 0.03MPa in the spherical tank, introducing olefin for 10 hours, introducing heat for 2 hours, collecting 106.2 parts of unreacted ethylene altogether, pressurizing and storing the ethylene in the spherical tank (about 5 MPa) by a pressurizing pump, adding 30% of liquid alkali in the materials in the kettle to 150 parts for neutralization to PH7.5, separating a salt water layer, adding the material layer into the rectifying tower kettle (theoretical plate number 250), discharging unreacted ethylene in-0.5 MPa, refluxing ratio 25-30, rectifying to obtain 99.9% phenol 271.6 parts (0925 ppm, containing nitrogen) by weight, 3.2ppm of sulfide-containing), 528.4 parts of 99.8% petrochemical interstage cresol (0.7 ppm of nitride-containing compound and 0.9ppm of sulfide-containing compound), and then 418.1 parts of 99.6% o-isopropyl phenol, 263 parts of 96.5% crude p-isopropyl phenol (253.8 parts of p-isopropyl phenol and 9.2 parts of m-isopropyl phenol), 299.5 parts of 99.6% 2-isopropyl-5-cresol (thymol) and 168.2 parts of 99.5% high-efficiency bactericide 4-isopropyl-3-cresol are obtained in sequence;

adding 263 parts of 96.5% p-isopropyl phenol crude product and 200 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 35 ℃ with circulating water for 2.5 hours, cooling to 0 ℃ with chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 241.3 parts of 99.6% p-isopropyl phenol, and refining the product with the yield of 94.7%;

2.2 Synthesis of Parafresh phenol and the like

While synthesizing thymol and the like, adding 685 parts of 99% coking phenol (1080 ppm containing nitride and 462ppm containing sulfide) and 25 parts of sulfuric acid/phosphoric acid (1.9 times of the molar mass of phenol is 2-ethyl-6-cresol, the mass ratio of 98% sulfuric acid to 85% phosphoric acid is 9:1) into a stainless steel pressure kettle, starting stirring, heating to 220 ℃, slowly decompressing the pressurized ethylene collected in the ethylene spherical tank in the step 2.1, introducing the pressurized ethylene into the stainless steel pressure kettle for reaction, keeping the kettle temperature at 220-230 ℃, reacting at 0.9-1.0 MPa, introducing olefin for 8 hours, stopping ventilation when the pressure on the spherical tank is reduced to 1.2MPa, keeping the pressure of the pressure kettle for 3 hours, adding 30% liquid alkali 70 parts into materials in the kettle for neutralization to PH7.5, separating a salt water layer, adding the material layer into the rectifying tower (200 theoretical plate number), rectifying the materials at-0.09 MPa, refluxing for 10-15 ppm, and obtaining the 5.99.99 ppm containing phenol, and the rest of the other 5.29% of the crude phenol (537.2 ppm containing p-ethyl phenol, and the rest of the p-1.2);

Adding 206 parts of 96.46% crude p-ethyl phenol and 120 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 35 ℃ in cold water bath for 2 hours, cooling to 0 ℃ in ice water bath for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 190.6 parts of 99.53% p-ethyl phenol, and refining yield is 95.5%;

step three, rectifying and separating the cracked product

35 Parts of a cleavage reaction product obtained in the step one (comprising 422.1 parts of cresol, 815.6 parts of phenol, 1164.8 parts of 2, 4-xylenol, 4484.6 parts of 2, 5-xylenol, 1799.8 parts of 3, 4-xylenol, 612 parts of 2, 3-xylenol, 450.1 parts of p-cresol, and 41.2 parts of the other components) are added into a distillation column kettle (100 parts of dimethyl diphenyl ether high boiling point solvent is added into the column kettle), vacuum distillation (vacuum degree-0.088 MPa, reflux ratio 15-25:1) is carried out, 99.1 parts of phenol with a concentration of 99.1 percent (applied to the step two), 635.6 parts of phenol with a petrochemical grade of 99.8 percent (0.9 ppm of nitrogen-containing compound, 1.1ppm of sulfur-containing compound), 411.6 parts of cresol with a petrochemical grade of 99.2 percent (2.0 parts of phenol, 146.8 parts of o-cresol, 74.7 parts of p-cresol, 186.8 parts of m-cresol, 1.3 parts of o-ethylphenol) are obtained, 0.6ppm containing nitrides, 0.8ppm containing sulfides), 5502.4 parts of 99.12%2,5/2, 4-xylenol (1119.3 parts of 2, 4-xylenol, 4334.7 parts of 2, 5-xylenol, 6.6 parts of m-p-cresol, 41.8 parts of 2, 3-xylenol, 78.78 parts of 2, 5-xylenol), 557.2 parts of mixed xylenol (33.8 parts of 2, 5-xylenol, 105 parts of 2, 3-xylenol, 382.9 parts of 3, 5-xylenol, 34.3 parts of m-p-ethylphenol, 68.72 parts of 2, 3-xylenol), 1776.4 parts of 96.76%3, 5-xylenol crude product (17.8 parts of 2, 3-xylenol, 1718.9 parts of 3, 4-xylenol, 39.2 parts of m-p-ethylphenol), 577.3 parts of 94.53%3, 4-xylenol crude product (2, 3-xylenol, 3, 1.2 parts of m-p-ethylphenol, 68.72 parts of 3, 3-xylenol);

99.2% petrochemical-grade cresol can be used for rectifying 99.5% o-cresol and 99% m-cresol products, and is mainly used for preparing cresol-novolac resin for photoresist, flame retardant plasticizer and the like;

99.12 percent of 2,5/2, 4-xylenol (2, 5-xylenol content 78.78 percent) can be used for t-butyl separation to produce 6-t-butyl-2, 4-xylenol and 4-t-butyl-2, 5-xylenol products, and can also be used for producing 2, 5-xylenol by a solvent crystallization method, 96.76 percent of 3, 5-xylenol crude products and 94.53 percent of 3, 4-xylenol crude products can be used for producing pure 3, 5-xylenol and 3, 4-xylenol by a solvent crystallization or melt crystallization method;

step four, refining the cracking rectification crude product

Adding 1776.4 parts of a crude product of the 3, 5-xylenol with the concentration of 96.76% and 1500 parts of methanol in a reactor, starting stirring, heating to 60 ℃ to completely dissolve materials, then cooling to 33 ℃ with circulating water for 3 hours, cooling to-10 ℃ with chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 1643.2 parts of the 3, 5-xylenol with the concentration of 99.58% and the refining yield of 95.2%;

Adding 577.3 parts of a step III 94.53%3, 4-xylenol crude product and 1800 parts of 90-120 ℃ petroleum ether into a reactor, starting stirring, heating to 80 ℃ to completely dissolve materials, then cooling to 38 ℃ by using circulating water for 3.5 hours, cooling to 15 ℃ by using chilled brine for 4 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 494.1 parts of 99.52%3, 4-xylenol, and refining the product with a yield of 90.1%;

4.3 adding 1000 parts of 99.12 percent 2,5/2, 4-xylenol (78.78 percent of 2, 5-xylenol) and 500 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to completely dissolve materials, then cooling to 36 ℃ by using circulating water for 2 hours, cooling to-10 ℃ by using chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping, drying to obtain 544.3 parts of 99.68 percent 2, 5-xylenol, and refining the product with the yield of 68.9 percent;

step five, separating the mixed xylenol obtained by cracking and rectifying by isohexyl

Adding 557.2 parts of mixed xylenol (33.8 parts of 2, 4-xylenol, 105 parts of 2, 5-xylenol, 382.9 parts of 2, 3-xylenol, 34.3 parts of 3, 5-xylenol and 1.2 parts of m-p-ethylphenol) obtained in the step three and 1 part of 6-isohexyl-2, 4-xylenol into a pressure kettle, adding 110 parts of strong acid resin, stirring and heating to 110 ℃ for reaction, introducing vaporized isohexene until the pressure of the reaction kettle is 0.6MPa, and introducing isohexene again to 0.6MPa when the pressure in the kettle is reduced to 0.1MPa, so that the reaction is repeated; when the pressure in the kettle is slowly reduced, sampling and analyzing that 0.32% of 2, 3-xylenol is qualified, the reaction time is 9 hours, the dosage of isohexide is 342 parts (the dosage of isohexide is 1.19 times of the molar quantity of 2,4/2, 3-xylenol in the mixed xylenol), the reaction is completed, the temperature is reduced to 80 ℃, the mixture is filtered, the filtrate is subjected to reduced pressure rectification (-0.095 MPa, the reflux ratio is 25-30:1) to obtain 94.9 parts of 98.68%2, 5-xylenol and 28.5 parts of 99.33%3, 5-xylenol, the yields are 89.2% and 82.6%, the yield is 47.7 parts of antioxidant 99.09% 6-isohexyl-2, 4-xylenol, and the yield is 82.8%, and 590.6 parts of 96.97% 6-isohexyl-2, 3-xylenol is obtained, and the yield is 88.6%;

adding 590.6 parts of sulfuric acid into a decomposing kettle, stirring, adding 5 parts of sulfuric acid, heating to 190 ℃ for 2 hours to remove isohexide, rectifying (-0.09 MPa, reflux ratio 25-30:1) to obtain 342.1 parts of 99.15%2, 3-xylenol with yield of 93.3%, adding high-boiling dimethyl diphenyl ether into the rectifying tower kettle in advance, and recycling 237.8 parts of isohexide;

Adding 94.9 parts of 98.68%2, 5-xylenol and 60 parts of methanol into a reactor, starting stirring, heating to 65 ℃ to enable materials to be completely dissolved, then cooling to 34 ℃ with circulating water for 2 hours, cooling to-10 ℃ with chilled brine for 3 hours, preserving heat for 2 hours, filtering, pumping and drying to obtain 87.1 parts of 99.83%2, 5-xylenol, and refining yield is 93.8%;

Adding 2000 parts of 99.12%2,5/2, 4-xylenol (406.8 parts of 2, 4-xylenol, 1575.6 parts of 2, 5-xylenol, 2.4 parts of m-p-cresol and 15.2 parts of 2, 3-xylenol) obtained in the step three and 2 parts of 6-isononyl-2, 4-xylenol into an autoclave, adding 300 parts of strong acid resin, stirring and heating to 130 ℃, dropwise adding isononane for reaction for 8 hours, keeping the temperature for 2 hours, sampling and analyzing that 0.15% of 2, 4-xylenol is qualified, 480 parts of isononane (1.14 times of the molar amount of 2, 4-xylenol in 2,5/2, 4-xylenol), reducing the temperature to 80 ℃, filtering, decompressing and rectifying the filtrate (-0.095 MPa) to obtain 1488.7 parts of 99.7%2, 5-xylenol with the yield of 94.2% and 99.2% of antioxidant (6-isononyl-2, 4-xylenol, 763.5.91% of the yield.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.

Claims

1. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol, characterized in that it comprises the following steps:

Step 1: Cleavage and translocation reaction:

A stainless steel high-pressure reactor is loaded with an acidic silicon-aluminum-chromium oxide solid catalyst and zirconium phosphate, and a 2,4-dimethylphenol/2,5-dimethylphenol mixture is added, the reactor is sealed, and the temperature is raised to 280-400° C. for reaction for 3-10 hours, and the pressure is gradually raised to 2.5-5.0 MPa, and the reaction is terminated. The inner coil is cooled with a programmed cooling heat transfer oil, and the temperature is rapidly lowered to 280-300° C. within 1-2 hours, and then the temperature is lowered to ≤150° C. within 0.5-1 hour, and propylene and ethylene released in the reaction are gradually discharged; the discharged gas is pressurized by a pressure pump and stored in a stainless steel spherical tank; after the gas is discharged, the cracking reaction condensate is slightly cooled and replaced with nitrogen for 0.5 hours, and the cracking reaction product is obtained by filtration, and the solid catalyst is applied;

Step 2: Synthesis of 2-isopropyl-5-methylphenol and 4-isopropyl-3-methylphenol and or o-/p-isopropylphenol and or ethylphenol, comprising:

2.1 Synthesis of thymol and o-isopropylphenol;

2.1.1 Synthesis of thymol:

At the same time as the cracking and transposition reactions in step 1, m-cresol, an acidic catalyst and a polymerization inhibitor are added to another stainless steel autoclave, stirring is started, and the temperature is raised to 160-170° C. The olefins stored in the spherical tank discharged after the cracking reaction in step 1 is cooled are simultaneously slowly decompressed and introduced into the stainless steel autoclave for reaction, the autoclave temperature is maintained at 170-200° C. The olefins are repeatedly introduced multiple times until the pressure in the autoclave is maintained at 2.3-2.5 MPa; when the pressure in the spherical tank drops to 2.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene in the autoclave is discharged; then the olefins in the spherical tank are repeatedly introduced multiple times to react until the pressure in the autoclave is 1.3-1.5 MPa, and when the pressure in the spherical tank drops to 1.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene is discharged; the olefins are repeatedly introduced into the autoclave for reaction until the pressure in the autoclave is 0.6 MPa, and when the pressure in the spherical tank drops to 0.7 MPa and the pressure in the autoclave no longer drops, the olefins are discharged. Unreacted ethylene; passing olefin to react until the pressure in the autoclave is 0.1MPa, and discharging unreacted ethylene when the pressure in the spherical tank drops to 0.1MPa and the pressure in the autoclave no longer decreases; continuing to pass olefin to react until the pressure in the spherical tank is 0.03MPa and then venting is terminated, the olefin passing time is 3 to 12 hours, and the reaction is carried out by heat preservation for 1 to 4 hours after the passing, and a total of 160.7 parts of unreacted ethylene are collected, and the ethylene is pressurized and stored in the spherical tank (about 5MPa) by a pressure pump; the autoclave is cooled to ≤90°C in 1 to 3 hours, 10 to 35% liquid alkali is added to the material in the autoclave to neutralize to pH7 to 8, the desalted water layer is separated, and the material layer is added to the autoclave of the distillation tower, and the unreacted m-cresol is obtained by distillation at -0.085 to -0.095MPa and a reflux ratio of 10 to 20, and then ≥99% 2-isopropyl-5-cresol and ≥99% high-efficiency fungicide 4-isopropyl-3-cresol are obtained in sequence;

2.1.2 Synthesis of o-isopropylphenol:

In step 1, while the cracking and transposition reactions are being carried out, phenol, an acidic catalyst and a polymerization inhibitor are added to another stainless steel autoclave, stirring is started, and the temperature is raised to 160-170° C. The olefins stored in the spherical tank discharged after the cracking reaction in step 1 is cooled are simultaneously slowly decompressed and introduced into the stainless steel autoclave for reaction, the autoclave temperature is maintained at 170-200° C. The olefins are repeatedly introduced multiple times until the pressure in the autoclave is maintained at 2.3-2.5 MPa; when the pressure in the spherical tank drops to 2.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene in the autoclave is discharged; then the olefins in the spherical tank are repeatedly introduced multiple times to react until the pressure in the autoclave is 1.3-1.5 MPa, and when the pressure in the spherical tank drops to 1.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene is discharged; the olefins are repeatedly introduced into the autoclave for reaction until the pressure in the autoclave is 0.6 MPa, and when the pressure in the spherical tank drops to 0.7 MPa, the pressure is discharged. When the pressure of the autoclave is no longer reduced, the unreacted ethylene is discharged; the olefin is passed through the reaction until the pressure in the autoclave is 0.1MPa, and the unreacted ethylene is discharged when the pressure of the spherical tank is reduced to 0.1MPa and the pressure of the autoclave is no longer reduced; the olefin is continued to react until the pressure of the spherical tank is 0.03MPa and the ventilation is terminated, the olefin passing time is 3 to 12 hours, and the heat preservation reaction is performed for 2 hours after the passing, and the unreacted ethylene is collected, and the ethylene is pressurized and stored in the spherical tank (about 5MPa) by a pressure pump; the pressure autoclave is cooled to ≤90°C in 1 to 3 hours, 10 to 35% liquid alkali is added to the material in the autoclave to neutralize to pH7 to 8, the salt water layer is separated, and the material layer is added to the reactor of the distillation tower, and the unreacted phenol is distilled at -0.085 to -0.095MPa and a reflux ratio of 10 to 20, and then ≥99% o-isopropyl phenol and ≥95% p-isopropyl phenol crude products are obtained in turn;

Add crude p-isopropylphenol and 90-120°C petroleum ether into a reactor, start stirring, heat to 70-90°C to completely dissolve the materials, then cool to 30-40°C with circulating water for 2-3 hours, then cool to 0-20°C with frozen brine for 2-4 hours, keep warm for 1-3 hours, filter, drain, and dry to obtain p-isopropylphenol with a concentration of ≥99%;

2.1.3 Synthesis of thymol and p-isopropylphenol:

At the same time as the cracking and transposition reactions in step 1, m-cresol, phenol, an acidic catalyst and a polymerization inhibitor are added to another stainless steel autoclave, stirring is started, the temperature is raised to 160-170° C., the olefins stored in the spherical tank discharged after the cracking reaction in step 1 is cooled down are simultaneously slowly decompressed and introduced into the stainless steel autoclave for reaction, the autoclave temperature is maintained at 170-200° C., the olefins are repeatedly introduced multiple times until the pressure in the autoclave is maintained at 2.3-2.5 MPa; when the pressure in the spherical tank drops to 2.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene in the autoclave is discharged; then the olefins in the spherical tank are repeatedly introduced multiple times to react until the pressure in the autoclave is 1.3-1.5 MPa, and when the pressure in the spherical tank drops to 1.6 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene is discharged; the olefins are repeatedly introduced into the autoclave for reaction until the pressure in the autoclave is 0.6 MPa, and when the pressure in the spherical tank drops to 0.7 MPa and the pressure in the autoclave no longer drops, the unreacted ethylene is discharged. The corresponding ethylene; olefin is reacted until the pressure in the autoclave reaches 0.1MPa, and the unreacted ethylene is discharged when the pressure in the spherical tank drops to 0.1MPa and the pressure in the autoclave no longer decreases; the olefin is continued to react until the pressure in the spherical tank reaches 0.03MPa and the ventilation is terminated. The olefin is passed for 3 to 12 hours, and the reaction is carried out by heat preservation for 2 hours after the olefin is passed. The unreacted ethylene is collected and stored in the spherical tank under pressure by a pressure pump; the pressure autoclave is cooled to ≤90℃ in 1 to 3 hours, and then the pressure is reduced to ≤90℃. 10-35% liquid alkali is added to the materials in the kettle to neutralize to pH 7-8, the salt water layer is separated, and the material layer is added to the kettle of the distillation tower. At -0.085-0.095MPa and a reflux ratio of 10-20, unreacted m-cresol and phenol are distilled and used, and then ≥99% o-isopropylphenol, ≥95% p-isopropylphenol, ≥99% 2-isopropyl-5-methylphenol, and ≥99% high-efficiency fungicide 4-isopropyl-3-methylphenol are obtained in sequence;

2.2 Synthesis of p-ethylphenol:

While synthesizing thymol and the like, phenol and an acid catalyst are added to a stainless steel autoclave, stirring is started, and the temperature is raised to 210-250° C. The pressurized ethylene collected in the ethylene spherical tank in step 2.1 is slowly decompressed and introduced into the stainless steel autoclave for reaction, the autoclave temperature is maintained at 220-250° C., the pressure is 0.9-1.0 MPa, the olefin feeding time is 4-10 hours, and ventilation is stopped when the pressure on the spherical tank drops to 1.0 MPa, the autoclave is kept warm for reaction for 1-4 hours, and the reaction is stopped when the autoclave pressure is stable and does not decrease; the autoclave is cooled to ≤90° C. in 1-3 hours, 10-35% liquid caustic soda is added to the material in the autoclave to neutralize to pH 7-8, the desalted water layer is separated, the material layer is added to the autoclave of a distillation tower, and the unreacted phenol is obtained by distillation at -0.085--0.095 MPa and a reflux ratio of 10-20, and then ≥99% o-ethyl phenol and ≥95% crude p-ethyl phenol are obtained in sequence;

Add crude p-ethylphenol and methanol into the reactor, start stirring, raise the temperature to 60-70°C to completely dissolve the materials, then cool it down to 30-40°C with circulating water for 2-3 hours, then cool it down to 0-10°C with frozen brine for 2-4 hours, keep it warm for 1-3 hours, filter, drain, and dry to obtain p-ethylphenol with a content of ≥99%;

Step 3: Distillation and separation of pyrolysis products:

Add the cleavage reaction product of step 1 to the reactor of a distillation tower, and perform vacuum distillation to obtain 99% phenol, 99% mixed cresols, ≥98% 2,5-xylenol/2,4-xylenol (2,5-xylenol/2,4-xylenol ≥98%, 2,5-xylenol ≥70%), mixed xylenols, ≥90% crude 3,5-xylenol, and ≥90% crude 3,4-xylenol;

99% mixed cresols can be used to distill 99.5% o-cresol and ≥98% m-cresol products;

≥98% 2,5-xylenol/2,4-xylenol can be used for tert-butylation separation to produce 6-tert-butyl-2,4-xylenol and 4-tert-butyl-2,5-xylenol products, and can also be used to produce 2,5-xylenol by solvent crystallization; crude 3,5-xylenol and crude 3,4-xylenol can be used to produce pure 3,5-xylenol and 3,4-xylenol by solvent crystallization or melt crystallization;

Mixed xylenols can be separated by alkylation to produce 2,4-xylenol, 2,5-xylenol, 2,3-xylenol, m-ethylphenol, p-ethylphenol, etc.

Step 4: Refining of crude product by cracking and distillation:

4.1 Add the crude 3,5-xylenol from step 3 and the solvent into the reactor, start stirring, raise the temperature to 60-90°C to completely dissolve the materials, then cool it down to 30-40°C with circulating water for 1-3 hours, then cool it down to 0-20°C with frozen brine for 1-3 hours, keep it warm for 1-2 hours, filter, drain, and dry to obtain ≥99% 3,5-xylenol;

4.2 Add the crude 3,4-xylenol from step 3 and the solvent into the reactor, start stirring, raise the temperature to 60-90°C to completely dissolve the materials, then cool it down to 30-40°C with circulating water for 1-3 hours, then cool it down to 0-20°C with frozen brine for 1-3 hours, keep it warm for 1-2 hours, filter, drain, and dry to obtain ≥99% 3,4-xylenol;

4.3 Add 500 parts of 2,5-xylenol/2,4-xylenol and solvent from step 3 into the reactor, start stirring, raise the temperature to 60-90°C to completely dissolve the materials, then cool it down to 30-40°C with circulating water for 1-3 hours, then cool it down to 0-20°C with frozen brine for 1-3 hours, keep it warm for 1-2 hours, filter, drain, and dry to obtain ≥99% 2,5-xylenol;

Step 5: Alkylation and separation of the mixed xylenols obtained by cracking and distillation:

5.1 Octylation separation, add the mixed xylenol and diisobutylene obtained in step 3 into a pressure reactor, add an acidic catalyst, stir and heat to 100-150°C for reaction, the reaction time is 2-12 hours, sample and analyze 2,3-xylenol ≤0.5% qualified, filter, and distill the filtrate to recover diisobutylene for application; then obtain ≥95% 2,5-xylenol and 99% 3,5-xylenol; antioxidant 99% 6-isooctyl-2,4-xylenol; obtain ≥95% 6-isooctyl-2,3-xylenol; the reactor residue mainly contains part of 6-isooctyl-m-ethylphenol, 2,6-diisooctyl-p-ethylphenol, etc.;

Add ≥95% 6-isooctyl-2,3-xylenol to a decomposition kettle, stir, add ≥95% sulfuric acid, heat to 180-200°C for 0.5-2 hours, take samples for analysis, and if 6-isooctyl-2,3-xylenol ≤0.5% is qualified, cool to 70-90°C, add 10-35% sodium hydroxide aqueous solution to neutralize to pH 7-7.5, perform atmospheric distillation to obtain diisobutylene, and then perform vacuum distillation to obtain 99% 2,3-xylenol;

Add ≥95% 2,5-xylenol and methanol into a crystallization reactor, start stirring, heat to 60-70°C to completely dissolve the materials, then cool to 30-40°C with circulating water for 1-3 hours, then cool to 0-20°C with frozen brine for 1-3 hours, keep warm for 1-2 hours, filter, drain, and dry to obtain ≥99% 2,5-xylenol;

5.2 Isohexylation separation, add the mixed xylenol and 6-isohexyl-2,4-xylenol obtained in step 3 into a pressure autoclave, add strong acid resin, stir and heat to 100-150°C for reaction, introduce vaporized isohexene until the pressure of the reactor reaches 0.6MPa, and when the pressure in the reactor drops to 0.1MPa, introduce vaporized isohexene again to 0.6MPa, and react multiple times in this way; when the pressure in the reactor drops slowly, sample and analyze 2,3-xylenol ≤0.5% and pass, the reaction time is 4-12 hours, after the reaction is completed, cool to 70-90°C for filtration, and conduct vacuum distillation of the filtrate to obtain ≥98% 2,5-xylenol and ≥99% 3,5-xylenol; obtain 99% 6-isohexyl-2,4-xylenol; obtain 95% 6-isohexyl-2,3-xylenol;

Add 6-isohexyl-2,3-xylenol into the decomposition kettle, start stirring, add sulfuric acid, heat to 180-200°C and keep the temperature for 0.5-3 hours to remove isohexene, and obtain 99% 2,3-xylenol by distillation. The isohexene can be used for recycling;

Add ≤99% 2,5-dimethylphenol and methanol into the reactor, start stirring, heat to 65°C to completely dissolve the materials, then cool to 30-40°C with circulating water for 2-4 hours, then cool to -10-10°C with frozen brine for 2-4 hours, keep warm for 1-3 hours, filter, drain, and dry to obtain 99.5% 2,5-dimethylphenol;

Step 6: Alkylation separation of 2,5-dimethylphenol/2,4-dimethylphenol:

The ≥98% 2,5-xylenol/2,4-xylenol and 6-isononyl-2,4-xylenol obtained in step 3 are added into a pressure autoclave, a strong acid resin is added, the temperature is raised to 100-180°C with stirring, isononene is added dropwise for reaction, the addition time is 4-12 hours, and the reaction is kept warm for 1-4 hours after the addition is completed. The 2,4-xylenol is sampled and analyzed, and the qualified is ≤0.3%, the amount of isononene is analyzed, the reaction is completed, the temperature is lowered to 70-100°C, and the filtrate is subjected to vacuum distillation (-0.09--0.1MPa, reflux ratio 10-30:1) to obtain ≥99.5% 2,5-xylenol; ≥99% antioxidant 6-isononyl-2,4-xylenol.

2. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that a 2,4-dimethylphenol/2,5-dimethylphenol mixture is added in step 1, the ratio of 2,4-dimethylphenol to 2,5-dimethylphenol in the 2,4-dimethylphenol/2,5-dimethylphenol mixture is 0.5-2:1, 2,4-dimethylphenol/2,5-dimethylphenol is 50-97%, preferably 70-90%, and the ratio of o-isopropylphenol/o-propylphenol in the 2,4-dimethylphenol/2,5-dimethylphenol mixture is 1-30%, preferably 5-20%; and the ratio of 2-ethyl-6-methylphenol is 0-30%, preferably 1-20%.

3. A process for preparing phenolic products from 2,4-xylenol/2,5-xylenol according to claim 1, characterized in that in step 1, an acidic silicon-aluminum-chromium oxide solid catalyst is loaded into a stainless steel high-pressure reactor, the silicon-aluminum-chromium oxide is silicon dioxide, acidic alumina, and chromium oxide, wherein the mass ratio of silicon dioxide to acidic alumina is 0.1-10:10-0.1, preferably 0.2-5:5-0.2, the amount of chromium oxide is 0.01-0.2 of the mass of silicon dioxide, and the amount of silicon-aluminum-chromium oxide is 5-50% of the weight of the 2,4-xylenol/2,5-xylenol mixture.

4. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that in step 1, the temperature of the heat transfer oil is gradually and slowly reduced from a high temperature to 80°C, and the high temperature is 50 to 100°C lower than the cracking and transposition reaction temperature.

5. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that, in step one, a cleavage reaction product [a mixed phenol consisting of 2,5-dimethylphenol/2,4-dimethylphenol (2,5-dimethylphenol as the main component), other dimethylphenols (3,5-dimethylphenol as the main component) and some phenols, cresols (m-cresol as the main component) etc.] is obtained by filtering, wherein the cresol is a mixture consisting of m-cresol, p-cresol, o-cresol, o-ethylphenol etc., with m-cresol as the main component, and a cleavage reaction product [a mixed phenol consisting of 2,5-dimethylphenol/2,4-dimethylphenol (2,5-dimethylphenol as the main component), other dimethylphenols (3,5-dimethylphenol as the main component) and some phenols, cresols (m-cresol as the main component) etc.] is obtained by filtering, wherein the ratio of 2,4-dimethylphenol to 2,5-dimethylphenol is 1:2-5.

6. A process for preparing phenolic products from 2,4-xylenol/2,5-xylenol according to claim 1, characterized in that, in step 1, filtration is performed to obtain a cleavage reaction product [a mixed phenol composed of 2,5-xylenol/2,4-xylenol (2,5-xylenol as the main component), other xylenols (3,5-xylenol as the main component) and some phenols, cresols (meta-cresol as the main component) etc.], wherein the other xylenols are 3,5-xylenol, 2,3-xylenol, 3,4-xylenol, a small amount of m-p-ethylphenol, etc., with 3,5-xylenol as the main component.

7. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that the acidic catalyst in step 2.1 is at least one of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, benzenesulfonic acid, a solid acid catalyst, an acidic resin, zirconium oxide, acidic aluminum oxide, silicon oxide, etc., preferably a mixed acid of sulfuric acid and phosphoric acid, and the amount of the mixed acid is 0.5-5% of the mass of m-cresol or phenol or a mixture of m-cresol and phenol, wherein the mass ratio of sulfuric acid to phosphoric acid is 5-7:5-3.

8. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that the acidic catalyst in step 2.2 is at least one of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, benzenesulfonic acid, a solid acid catalyst, an acidic resin, zirconium oxide, acidic aluminum oxide, silicon oxide, etc., preferably a mixed acid of sulfuric acid and phosphoric acid, and the amount of the mixed acid is 1-5% of the mass of phenol, wherein the mass ratio of sulfuric acid to phosphoric acid is 9-7:1-3.

9. A process for preparing phenolic products from 2,4-dimethylphenol/2,5-dimethylphenol according to claim 1, characterized in that, in step 2.1, the polymerization inhibitor is hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 6-tert-butyl-2,4-dimethylphenol, p-methoxyphenol, etc., preferably 2-methylhydroquinone, and in step 2.1.3, m-cresol and phenol are added to another stainless steel pressure autoclave, and the mass ratio of m-cresol to phenol is 1:0.5-2.

10. A process for preparing phenolic products from 2,4-xylenol/2,5-xylenol according to claim 1, characterized in that, in step 3, the mixed xylenols are composed of two or more of 2,4-xylenol, 2,5-xylenol, 2,3-xylenol, 3,5-xylenol, a small amount of m-p-ethylphenol, etc., 2,3-xylenol is the main solvent, and the content is generally not less than 50%; in step 4.1, 4.2, and 4.3, the solvent is alcohol, alkane, ether, ester, ketone, etc., preferably methanol and petroleum ether; in step 5, an acidic catalyst is added, and the acidic catalyst is an inorganic acid such as sulfuric acid and phosphoric acid, an organic acid such as aminosulfonic acid, benzenesulfonic acid, toluenesulfonic acid, a solid acid loaded with antimonic acid, etc., a strong acid resin, etc., preferably a strong acid resin.