A method for resourceful treatment and recovery of phenol-ketone tar

Abstract

The application provides a phenol ketone tar resource treatment and recovery method, which comprises the following steps: (1) performing light fraction removal on the phenol ketone tar to separate out a light fraction and obtain a light fraction removal material; and (2) adding a cracking catalyst and water into the light fraction removal material, and performing a cracking reaction under the condition of higher than one standard atmosphere and higher than room temperature to obtain a cracking product. The application also provides a process device for implementing the method.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to a method for the resource-based treatment and recovery of phenolic tar. Background Technology

[0002] Phenol is an important chemical raw material, widely used in the industrial production of plastics, synthetic fibers, pharmaceuticals, pesticides, and fuel intermediates. In the cumene process for phenol and acetone production, a large amount of heavy component tar, known as phenol tar, is discharged from the system after product separation. The main components of phenol tar are: phenol 3–10%, acetophenone 10–25%, α-methylstyrene dimer 8–20%, 2-cumylphenol 1–8%, 4-cumylphenol 15–40%, and heavy components 15–30%. Due to differences in production processes, the composition of the tar produced varies considerably from unit to unit.

[0003] In 2023, my country's phenol-acetone plant capacity was approximately 10.23 million tons / year, generating about 315,000 tons / year of phenol-acetone tar. Currently, the conventional method for treating phenol-acetone tar is to incinerate the byproduct steam, but this has limited economic benefits and causes significant environmental problems. Some studies have proposed extracting high-value components (phenol and acetophenone) from phenol-acetone tar, with the remaining tar then incinerated, thus increasing the added value of phenol-acetone tar. However, since phenol and acetophenone together account for approximately 13-35% of phenol-acetone tar, most of the tar still needs to be incinerated, resulting in limited environmental improvement.

[0004] Further research has proposed using high-temperature pyrolysis of the remaining tar after recovering phenol and acetophenone to crack α-methylstyrene dimer and 2-cumylphenol (ortho-cumylphenol) and 4-cumylphenol (para-cumylphenol), which can produce α-methylstyrene. Alpha-methylstyrene, when hydrogenated with phenol, produces cumene, which is then returned to the system as a raw material. However, alpha-methylstyrene is unstable and prone to self-polymerization or reaction with phenol to form heavier components with larger molecular weights. Therefore, the total yield of alpha-methylstyrene and phenol during high-temperature cracking is only about 60-70%, and subsequent processes involving hydrogenation and other high-risk steps are not economical or safe, making practical application difficult.

[0005] To further enhance the added value of phenol-ketone tar, increase the yield of valuable products from the tar, reduce the amount of tar burned, and decrease carbon emissions, it is of great significance to develop a simple, efficient, safe, and economical method for the resource utilization of phenol-ketone tar. Summary of the Invention

[0006] In view of the current problems of low target product yield, complex process, and high production cost in the recovery of useful products from phenol-ketone tar cracking, this invention provides a method for the resource recovery of phenol-ketone tar under high pressure catalytic cracking, the method comprising:

[0007] (1) Remove light fractions from phenol tar to obtain light fractions;

[0008] (2) Add a cracking catalyst and water to the light material and carry out the cracking reaction under conditions above one standard atmosphere and above room temperature to obtain cracking products.

[0009] The pyrolysis products of this invention can be directly separated to obtain cumene and phenol. Compared with conventional high-temperature pyrolysis methods, this method directly generates cumene and phenol without generating α-methylstyrene. This is because under high temperature and high pressure, α-methylstyrene dimer and 2-cumylphenol and 4-cumylphenol in tar can all form cumyl radicals, which combine with hydrogen radicals generated by water under high pressure to form cumene. The following chemical formulas illustrate the formation mechanism of cumene under high temperature and high pressure (taking α-methylstyrene dimer and 4-cumylphenol as examples).

[0010]

[0011] In addition, the cleavage of α-methylstyrene dimer produces small amounts of ethylbenzene and butylbenzene (e.g., sec-butylbenzene).

[0012] The high-pressure catalytic cracking method for phenol and ketone tar reduces subsequent hydrogenation steps. After separation, cumene can be directly returned to the phenol and ketone unit as a feedstock. The process is simple, the yield of the target cracking product is high, and the economic benefits are good.

[0013] In some embodiments, the method of the present invention further includes further processing of the light fraction to separate phenol and acetophenone.

[0014] In some embodiments, the method of the present invention further includes further processing of the pyrolysis products to separate ethylbenzene, cumene, and phenol products.

[0015] In another aspect, the present invention also provides a process apparatus for carrying out the method of the present invention, comprising at least an apparatus for removing light from phenolic tar and an apparatus for carrying out a pyrolysis reaction.

[0016] In some embodiments, the process apparatus of the present invention further includes a device for further processing the separated light fractions.

[0017] In some embodiments, the process apparatus of the present invention further includes means for further processing of the pyrolysis products.

[0018] The process apparatus of the present invention may also include any other apparatus that can be used to implement the method of the present invention. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the process for the phenol-ketone tar resource utilization device in Example 1; the reference numerals are explained as follows:

[0020] 1-Phenolic ketone tar feed tank; 2-Light oil removal distillation column; 3-Condenser of the first distillation unit; 4-First distillation unit; 5-Phenol receiving tank; 6-Condenser of the second distillation unit; 7-Second distillation unit; 8-Acetophenone receiving tank; 9-High-pressure cracking reactor; 10-Condenser of the third distillation unit; 11-Third distillation unit; 12-Ethylbenzene receiving tank; 13-Condenser of the fourth distillation unit; 14-Fourth distillation unit; 15-Cumene receiving tank; 16-Condenser of the fifth distillation unit; 17-Fifth distillation unit; 18-Phenol receiving tank; 19-Heavy oil receiving tank. Detailed Implementation

[0021] The "range" disclosed herein is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0022] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0023] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0024] In this application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0025] In this application, unless otherwise specified, the terms "comprising" and "including" as used herein are open-ended or closed-ended. For example, "comprising" and "including" may mean that other components not listed may also be included, or that only the listed components may be included.

[0026] In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the number itself, and "several" in "one or more" means two or more.

[0027] In this description, unless otherwise stated, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0028] Unless otherwise specified, percentages (%) or parts refer to weight percentages or parts relative to the composition.

[0029] Unless otherwise stated herein, the sum of the contents of the components in the composition is 100%.

[0030] Unless otherwise stated herein, the sum of the parts of each component in the composition may be 100 parts by weight.

[0031] In this document, unless otherwise stated, “combination of” means a multi-component mixture of the elements, such as two, three, four, and up to the maximum possible multi-component mixture.

[0032] Unless otherwise specified, the term "a" as used in this specification means "at least one".

[0033] In this paper, unless otherwise stated, all reactions were carried out at room temperature and pressure.

[0034] One aspect of this application provides a method for the resource-based treatment and recovery of phenolic tar, the method comprising:

[0035] (1) Remove light fractions from phenol tar to obtain light fractions;

[0036] (2) Add a cracking catalyst and water to the light material and carry out the cracking reaction under conditions above one standard atmosphere and above room temperature to obtain cracking products.

[0037] Phenolic tar

[0038] In this article, "phenol tar," also known as phenol tar, refers to the heavy component tar produced as a byproduct of the cumene process for producing phenol and acetone. During the cumene process, benzene and propylene react under a catalyst to produce cumene. Cumene then undergoes oxidation with oxygen to produce cumene hydroperoxide. Cubic hydroperoxide decomposes under the action of an acid (such as sulfuric acid) to produce phenol and acetone. Phenol and acetone are separated, leaving phenol tar as the remaining byproduct. Phenol tar has a complex composition, and due to differences in process routes and catalyst types used by different manufacturers, the proportions of each component in the phenol tar produced by different manufacturers will vary. The main components of phenol tar may include α-methylstyrene dimer, 2-cumylphenol, 4-cumylphenol, phenol, acetophenone, and heavy oil.

[0039] Light

[0040] In this article, "light component removal" refers to the separation of light and heavy components based on differences in volatility / boiling point. A light component removal column, also known as a light component removal column, is typically used for this purpose. This is a device that removes light components from a mixture by utilizing differences in volatility / boiling point. The working principle of a light component removal column is based on the different volatility of the components in the mixture. Inside the column, the mixture undergoes heating and condensation. Due to their higher volatility, the light components accumulate at the top of the column, while the heavy components accumulate at the bottom, yielding light fractions and removed light component material, respectively. By controlling the temperature and pressure at the top and bottom of the column, effective separation of the light components can be achieved.

[0041] In step (1) of the method of the present invention, the phenol-acetone tar is subjected to light removal. The purpose of light removal is to remove phenol and acetophenone from the phenol-acetone tar. Therefore, the separated light fraction mainly contains phenol and acetophenone. The light-removed material contains α-methylstyrene dimer, 2-cumylphenol, 4-cumylphenol, heavy oil, etc. For example, the light removal can be carried out using a negative pressure distillation device, such as a light removal column, with a theoretical plate number of 2 to 25, preferably 5 to 20, a pressure of 1 to 20 kPa, preferably 2 to 10 kPa, and a reflux ratio of 0.1 to 2, preferably 0.5 to 1.5.

[0042] Separation of light fractions

[0043] The separated light fraction can be further processed to separate phenol and acetophenone. The light fraction can be processed through at least two distillation separation units, such as a first distillation unit and a second distillation unit. For example, the first distillation unit has 20-120 theoretical plates, preferably 30-100, a pressure of 50-150 kPa, preferably 60-130 kPa, and a reflux ratio of 2-25, preferably 3-20; the second distillation unit has 10-120 theoretical plates, preferably 20-80, a pressure of 0.5-15 kPa, preferably 1-10 kPa, and a reflux ratio of 0.1-8, preferably 0.5-5.

[0044] Pyrolysis

[0045] In this article, “pyrolysis” refers to the chemical process by which a higher molecular weight substance is transformed into one or more lower molecular weight substances under conditions such as high temperature or a catalyst.

[0046] In step (2) of the method of the present invention, a pyrolysis catalyst and water are added to the light-weight material, and a pyrolysis reaction is carried out under high temperature and high pressure to obtain pyrolysis products. The pyrolysis targets mainly α-methylstyrene dimer, 2-cumylphenol, and 4-cumylphenol.

[0047] Preferably, the pyrolysis reaction pressure is 1–50 MPa, or 1.5–15 MPa, or 2–10 MPa. For example, the pyrolysis reaction pressure can be 1 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 3.6 MPa, 3.7 MPa, 3.8 MPa, 3.9 MPa, 4.0 MPa, 4.1 MPa, 4.2 MPa, 4.3 MPa, 4.4 MPa, 4.5 MPa, 4.6 MPa, 4.7 MPa, 4.8 MPa, 4.9 MPa, 5.0 MPa, 5.1 MPa, 5. 2Mpa, 5.3Mpa, 5.4Mpa, 5.5Mpa, 6.0Mpa, 6.5Mpa, 7.0Mpa, 7.5Mpa, 8.0Mpa, 8.5Mpa, 9.0Mpa, 9.5Mpa, 1 0Mpa, 11Mpa, 12Mpa, 13Mpa, 14Mpa, 15Mpa, 16Mpa, 17Mpa, 18Mpa, 19Mpa, 20Mpa, 30Mpa, 40Mpa, 50Mpa.

[0048] In this article, "room temperature" is also called normal temperature or ambient temperature, and is usually defined as 25°C.

[0049] The pyrolysis reaction temperature is 200–450℃, or 230–400℃, or 260–350℃. For example, the pyrolysis reaction temperature can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, or 450℃.

[0050] Preferably, the pyrolysis reaction time is 1–25 h, or 2–20 h, or 3–15 h.

[0051] The pyrolysis can be carried out in a high-pressure reactor. For example, the high-pressure reactor can be selected from high-pressure reactors, fixed-bed reactors, microchannel reactors, tubular reactors, etc. The pyrolysis can be carried out in a high-pressure pyrolysis reactor, such as a high-pressure pyrolysis reactor equipped with a stirrer.

[0052] Preferably, the pyrolysis reaction is carried out in an atmosphere of a non-reactive gas. More preferably, the pyrolysis reaction is carried out in an atmosphere selected from nitrogen, argon, or helium; for example, the pyrolysis reaction of the present invention is carried out in a nitrogen atmosphere. In this document, "non-reactive gas" refers to a gas that does not participate in the reaction of the present invention.

[0053] Cracking catalyst

[0054] In this invention, a cracking catalyst is added to the cracking reaction. The cracking catalyst can be selected from basic catalysts, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide. The cracking catalyst can be selected from solid basic catalysts. The cracking catalyst can be selected from acid catalysts, such as organic or inorganic acids, such as formic acid, acetic acid, hydrochloric acid, boric acid, phosphoric acid, and sulfuric acid. The cracking catalyst can be selected from solid acid catalysts. The cracking catalyst can be selected from oxide catalysts, such as Al₂O₃, MgO, CaO, Na₂O, K₂O, and SiO₂. The cracking catalyst can be selected from salt catalysts, such as sulfates, such as MgSO₄ and ZnSO₄. The cracking catalyst can be supported on a carrier.

[0055] Preferably, based on the weight of the removed light material, the catalyst dosage is 0.1–5 wt%, or 0.5–4 wt%, or 1.0–3 wt%. For example, the catalyst dosage can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2. 5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3.0 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4.0 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, 5.0 wt%.

[0056] Adding water

[0057] Water was added during the pyrolysis reaction in step (2). As mentioned above, the role of water is to generate hydrogen radicals under high pressure. Under high temperature and high pressure, α-methylstyrene dimer, 2-cumylphenol, and 4-cumylphenol can all form cumyl radicals, which combine with hydrogen radicals to form cumene.

[0058] Preferably, based on the weight of the removed light material, the amount of water added can be 0.1–5 wt%, or 0.5–4 wt%, or 1.0–3 wt%. Preferably, the amount of water added can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, or 2.4 wt%. 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3.0 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4.0 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, 5.0 wt%.

[0059] Separation of pyrolysis products

[0060] In this invention, the pyrolysis products may include cumene, phenol, and ethylbenzene. Optionally, the method of this invention further includes separating the pyrolysis products to obtain ethylbenzene, cumene, and phenol products respectively. For example, the pyrolysis products are passed through at least three distillation separation units to obtain ethylbenzene, cumene, and phenol products respectively. For example, the at least three distillation separation units include a third distillation unit, a fourth distillation unit, and a fifth distillation unit. For example, the third distillation unit has a theoretical plate number of 30-80, preferably 50-70, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.5-10, preferably 1-8; the fourth distillation unit has a theoretical plate number of 30-80, preferably 30-50, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.2-5, preferably 0.5-3; the fifth distillation unit has a theoretical plate number of 30-80, preferably 30-50, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.5-10, preferably 0.5-3.

[0061] For example, the cracking products are first transferred to the third distillation unit for distillation, and ethylbenzene is collected from the top of the third distillation unit; the bottom feed of the third distillation unit enters the fourth distillation unit, and isopropylbenzene is collected from the top of the fourth distillation unit; the bottom feed of the fourth distillation unit enters the fifth distillation unit, and phenol is collected from the top of the fifth distillation unit, while heavy oil is obtained from the bottom of the fifth distillation unit.

[0062] Another aspect of this application provides a process apparatus for implementing the method of any one of the preceding claims, comprising at least apparatus for removing light fractions from phenolic tar and apparatus for carrying out a cracking reaction. Optionally, the process apparatus of the present invention may further include apparatus for separating light fractions and / or apparatus for separating cracking products.

[0063] Lightweight device

[0064] In this invention, the apparatus for removing light components from phenolic tar can be a distillation unit, such as a negative pressure distillation unit. The apparatus for removing light components from phenolic tar can be a light component removal tower. A light component removal tower, also called a light component removal tower, is a device that utilizes the difference in volatility of substances to remove light components from a mixture. The working principle of a light component removal tower is based on the difference in volatility of the components in the mixture. Inside the tower, the mixture undergoes a heating and condensation process. Due to their high volatility, the light components accumulate at the top of the tower, while the heavy components accumulate at the bottom, yielding light fractions and removed light components, respectively. By controlling the temperature and pressure at the top and bottom of the tower, effective separation of the light components can be achieved.

[0065] In step (1) of the method of the present invention, the phenol-acetone tar is subjected to light removal. The purpose of light removal is to remove phenol and acetophenone from the phenol-acetone tar. Therefore, the separated light fraction mainly contains phenol and acetophenone. The light-removed material contains α-methylstyrene dimer, 2-cumylphenol, 4-cumylphenol, heavy oil, etc. For example, the light removal can be carried out using a negative pressure distillation device, such as a light removal column. The theoretical plate number of the negative pressure distillation device is 2 to 25, preferably 5 to 20, the pressure is 1 to 20 kPa, preferably 2 to 10 kPa, and the reflux ratio is 0.1 to 2, preferably 0.5 to 1.5.

[0066] Light fraction separation device

[0067] The separated light fraction can be further processed to separate phenol and acetophenone. The light fraction can be processed through at least two distillation separation units, such as a first distillation unit and a second distillation unit. For example, the first distillation unit has 20-120 theoretical plates, preferably 30-100, a pressure of 50-150 kPa, preferably 60-130 kPa, and a reflux ratio of 2-25, preferably 3-20; the second distillation unit has 10-120 theoretical plates, preferably 20-80, a pressure of 0.5-15 kPa, preferably 1-10 kPa, and a reflux ratio of 0.1-8, preferably 0.5-5.

[0068] For example, the light fraction first enters the first distillation unit, and a high content of phenol is collected from the top of the first distillation unit. The bottom material enters the second distillation unit, and a high content of acetophenone is collected from the top of the second distillation unit.

[0069] pyrolysis unit

[0070] In this document, "pyrolysis" refers to the chemical process by which a higher molecular weight substance is transformed into one or more lower molecular weight substances under conditions such as high temperature or a catalyst. Pyrolysis reactions can be carried out in high-pressure reactors. For example, such high-pressure reactors are selected from high-pressure reactors, fixed-bed reactors, microchannel reactors, tubular reactors, etc. The pyrolysis can be carried out in a high-pressure pyrolysis reactor, such as a high-pressure pyrolysis reactor equipped with a stirrer.

[0071] Preferably, the pyrolysis reaction pressure is 1–50 MPa, or 1.5–15 MPa, or 2–10 MPa. For example, the pyrolysis reaction pressure can be 1 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 3.6 MPa, 3.7 MPa, 3.8 MPa, 3.9 MPa, 4.0 MPa, 4.1 MPa, 4.2 MPa, 4.3 MPa, 4.4 MPa, 4.5 MPa, 4.6 MPa, 4.7 MPa, 4.8 MPa, 4.9 MPa, 5.0 MPa, 5.1 MPa, 5. 2Mpa, 5.3Mpa, 5.4Mpa, 5.5Mpa, 6.0Mpa, 6.5Mpa, 7.0Mpa, 7.5Mpa, 8.0Mpa, 8.5Mpa, 9.0Mpa, 9.5Mpa, 1 0Mpa, 11Mpa, 12Mpa, 13Mpa, 14Mpa, 15Mpa, 16Mpa, 17Mpa, 18Mpa, 19Mpa, 20Mpa, 30Mpa, 40Mpa, 50Mpa.

[0072] The pyrolysis reaction temperature is 200–450℃, or 230–400℃, or 260–350℃. For example, the pyrolysis reaction temperature can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, or 450℃.

[0073] Preferably, the pyrolysis reaction time is 1–25 h, or 2–20 h, or 3–15 h.

[0074] Device for separating pyrolysis products

[0075] In this invention, the pyrolysis products may include cumene, phenol, and ethylbenzene. Optionally, the method of this invention further includes separating the pyrolysis products to obtain ethylbenzene, cumene, and phenol products respectively. For example, the pyrolysis products are passed through at least three distillation separation units to obtain ethylbenzene, cumene, and phenol products respectively. For example, the at least three distillation separation units include a third distillation unit, a fourth distillation unit, and a fifth distillation unit. For example, the third distillation unit has a theoretical plate number of 30-80, preferably 50-70, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.5-10, preferably 1-8; the fourth distillation unit has a theoretical plate number of 30-80, preferably 30-50, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.2-5, preferably 0.5-3; the fifth distillation unit has a theoretical plate number of 30-80, preferably 30-50, a pressure of 3-25 kPa, preferably 5-20 kPa, and a reflux ratio of 0.5-10, preferably 0.5-3.

[0076] For example, the cracking products are first transferred to the third distillation unit for distillation, and ethylbenzene is collected from the top of the third distillation unit; the bottom feed of the third distillation unit enters the fourth distillation unit, and isopropylbenzene is collected from the top of the fourth distillation unit; the bottom feed of the fourth distillation unit enters the fifth distillation unit, and phenol is collected from the top of the fifth distillation unit, while heavy oil is obtained from the bottom of the fifth distillation unit.

[0077] Example

[0078] To make the technical solution and effects of the present invention clearer, the technical solution of the present invention will be further described below in conjunction with some specific embodiments. The described embodiments are for further illustrating the present invention and should not be construed as limiting the scope of protection of the present invention.

[0079] In the embodiments, unless otherwise specified, percentage (%) or parts refer to weight percentage or weight parts.

[0080] The phenol-acetone tar described in the embodiments and comparative examples of this invention is produced from the phenol-acetone unit of Jiangsu Ruiheng New Materials Co., Ltd. The composition of the phenol-acetone tar is as follows: phenol content 7.1%, acetophenone content 20.9%, α-methylstyrene dimer content 8.5%, 2-cumylphenol content 4.0%, 4-cumylphenol content 21.1%, and the remainder is heavy components.

[0081] For simplicity, since the pyrolysis feedstocks cumylphenol and α-methylstyrene dimer each contain two benzene rings, while the target products phenol and cumene each contain one benzene ring, the conversion and yield are calculated by combining the molar amounts of benzene rings.

[0082] Example 1

[0083] Phenolic tar was fed into a light distillation column with 10 trays, a pressure of 5 kPa, a reflux ratio of 1, a top temperature of 113°C, and a bottom temperature of 200°C to obtain the top effluent (light fraction) and the light-removed material (heavy fraction).

[0084] The weight of the effluent from the top of the tower accounts for 28.1% of the weight of the feed tar, of which phenol content is 25.5% and acetophenone content is 71.6%.

[0085] The effluent from the top of the column is further separated by two distillation units. The first distillation unit has 70 theoretical plates, a pressure of 80 kPa, a reflux ratio of 10, a top temperature of 172°C, and a bottom temperature of 194°C. Phenol with a purity of 96.5% is collected from the top of the column. The bottom material is fed into the second distillation unit, which has 70 theoretical plates, a pressure of 5 kPa, a reflux ratio of 1.5, a top temperature of 109°C, and a bottom temperature of 122°C. Acetophenone with a purity of 99.9% is collected from the top of the second distillation unit.

[0086] The light-removed material contained 11.3% α-methylstyrene dimer, 5.5% 2-cumylphenol, and 29.3% 4-cumylphenol, with the remainder being heavy components.

[0087] The light-weight material was added to a high-pressure pyrolysis reactor (Yantai Songling Chemical Equipment Co., Ltd., model: KCFD1-10), followed by 1.5% by weight of phosphoric acid and 2% by weight of water based on the weight of the light-weight material. The reactor was stirred under 1 MPa nitrogen pressure, heated to 320℃, and the pressure was gradually increased to approximately 4.5 MPa, then maintained at a stable temperature for 6 hours. After cooling, samples were taken to separate the pyrolysis product composition (GC internal standard analysis): ethylbenzene content 3.8%, cumene content 30.8%, phenol content 15.3%, heavy oil content 47.8%, α-methylstyrene dimer and 2-cumylphenol, 4-cumylphenol conversion rate 100%, and the combined molar yield of cumene and phenol from the pyrolysis reaction 99.5%.

[0088] The cracking products are transferred to the third distillation unit for further distillation. The third distillation unit has 50 theoretical plates, a pressure of 10 kPa, a reflux ratio of 2, a top temperature of 57°C, and a bottom temperature of 95°C. The top product is 95% ethylbenzene. The bottom product of the third distillation unit enters the fourth distillation unit, which has 50 theoretical plates, a pressure of 10 kPa, a reflux ratio of 2, a top temperature of 80°C, and a bottom temperature of 120°C. The top product is 99.9% cumene. The bottom product of the fourth distillation unit enters the fifth distillation unit, which has 50 theoretical plates, a pressure of 10 kPa, a reflux ratio of 3, a top temperature of 110°C, and a bottom temperature of 132°C. The top product is 99.3% phenol. Heavy oil accounts for 31.2% of the weight of the feed tar.

[0089] Example 2

[0090] Except for the use of solid NaOH instead of phosphoric acid as the cracking catalyst, the other conditions were the same as in Example 1. The composition of the cracking products was: ethylbenzene 4.6%, cumene 28.6%, phenol 14.2%, α-methylstyrene dimer 0.1%, 4-cumylphenol 0.1%, heavy oil 52.2%, the conversion rate of α-methylstyrene dimer and 2-cumylphenol, 4-cumylphenol was 99.6%, and the total molar yield of cumene and phenol in the cracking reaction was 92.1%.

[0091] Example 3

[0092] Except for the use of acetic acid instead of phosphoric acid as the cracking catalyst, the other conditions were the same as in Example 1. The composition of the cracking products was: ethylbenzene 5.5%, cumene 30.1%, phenol 15.3%, α-methylstyrene dimer 0.1%, 4-cumylphenol 0.2%, and heavy oil 48.1%. The conversion rates of α-methylstyrene dimer, 2-cumylphenol, and 4-cumylphenol were 99.3%, and the total molar yield of cumene and phenol in the cracking reaction was 99.1%.

[0093] Comparative Example 1

[0094] Except for the absence of a catalyst in the pyrolysis reaction, the other conditions were the same as in Example 1. The composition of the pyrolysis products was: ethylbenzene 1.1%, cumene 7.1%, α-methylstyrene 1.1%, phenol 5.4%, α-methylstyrene dimer 7.3%, 2-cumylphenol 3.2%, 4-cumylphenol 18.8%, and heavy oil 55.3%. The conversion rate of α-methylstyrene dimer and 2-cumylphenol, 4-cumylphenol was 36.4%, and the total molar yield of cumene and phenol in the pyrolysis reaction was 27.9%.

[0095] Comparative Example 2

[0096] Except that no water was added during the pyrolysis reaction, the other conditions were the same as in Example 1. The composition of the pyrolysis products was: ethylbenzene 4.4%, cumene 11.7%, α-methylstyrene 17.2%, phenol 15.1%, α-methylstyrene dimer 0.2%, 2-cumylphenol 0.2%, 4-cumylphenol 0.3%, heavy oil 50.2%, the conversion rate of α-methylstyrene dimer and 2-cumylphenol, 4-cumylphenol was 98.5%, the pyrolysis reaction generated a large amount of α-methylstyrene, and the total molar yield of cumene and phenol was 60.5%.

[0097] Comparative Example 3

[0098] Except for the use of atmospheric pressure pyrolysis, the other conditions were the same as in Example 1. Atmospheric pressure pyrolysis was carried out in a reactor equipped with a light component extraction device. The reactor was stirred and heated to 320°C and held for 6 hours. The amount of light component recovered from pyrolysis accounted for 47.5% of the amount of tar fed into the reactor. The composition of the light component was: ethylbenzene 4.7%, cumene 13.6%, α-methylstyrene 38.2%, and phenol 34.1%. The reactor feed consisted of heavy components. The conversion rate of α-methylstyrene dimer and 2-cumylphenol and 4-cumylphenol was 92.2%. The pyrolysis reaction generated a large amount of α-methylstyrene. The total molar yield of cumene and phenol was 64.8%.

[0099] Comparative Example 4

[0100] Except for the use of atmospheric pressure pyrolysis, no water was added during the reaction, and the holding time was extended. The other conditions were the same as in Example 1. Atmospheric pressure pyrolysis was carried out in a reactor equipped with a light component extraction device. The reactor was stirred and heated to 320°C and held for 8 hours. The amount of light component recovered from pyrolysis accounted for 59.1% of the amount of tar fed into the reactor. The composition of the light component was: 10.5% ethylbenzene, 15.2% cumene, 33.5% α-methylstyrene, and 25.0% phenol. The reactor feed consisted of heavy components. The conversion rate of α-methylstyrene dimer and 2-cumylphenol and 4-cumylphenol was 96.5%. The pyrolysis reaction generated a large amount of α-methylstyrene, and the total molar yield of cumene and phenol was 51.5%.

[0101] The pressure of pyrolysis

[0102] Based on Example 1, further Examples 4-5 and Comparative Example 3 were used to compare the results obtained by applying different pyrolysis pressures. Except for the different pyrolysis pressures, the other conditions in Examples 4-5 and Comparative Example 3 were the same as in Example 1.

[0103] The results are summarized in Table 1 below:

[0104] Table 1

[0105]

[0106]

[0107] As can be seen from the table above, too low a pressure is not conducive to the generation of hydrogen radicals from water, resulting in a low total molar yield of cumene and phenol; too high a pressure increases side reactions, and the cracking products react with each other to regenerate cumylphenol, resulting in a decrease in reaction conversion and yield.

[0108] Water addition amount

[0109] Based on Example 1, further Examples 5-7 and Comparative Example 2 were used to compare the results obtained by using different amounts of water. Except for the amount of water added, the other conditions in Examples 5-7 and Comparative Example 2 were the same as in Example 1.

[0110] The results are summarized in Table 2 below:

[0111] Table 2

[0112]

[0113] As can be seen from the table above, the yield decreases significantly if water is not added. Too little water results in fewer hydrogen radicals, leading to the cracking reaction that produces α-methylstyrene, which is detrimental to the formation of cumene; too much water, on the other hand, reduces the conversion rate of the cracking reaction.

[0114] catalyst

[0115] Based on Example 1, the results obtained using the catalyst were compared through further Examples 2-3, 8-13, and Comparative Example 1. Except for the catalyst, the other conditions in Examples 2-3, 8-13, and Comparative Example 1 were the same as in Example 1.

[0116] The results are summarized in Table 3 below:

[0117] Table 3

[0118]

[0119] As can be seen from the table above, the yields obtained using acid catalysts such as phosphoric acid, acetic acid, sulfuric acid, and zirconium sulfate are high. The conversion rate obtained using solid NaOH is also good, but the yield is slightly lower than that obtained using acid catalysts.

[0120] In summary, the high-pressure cracking method of this invention, by adding water and a cracking catalyst, can be used to recycle phenol tar to obtain cumene and phenol without generating α-methylstyrene, thus avoiding the subsequent hydrogenation step. It also has high conversion rate and selectivity, and the amount of heavy oil after cracking is greatly reduced.

[0121] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for recycling phenol-ketone tar, the method comprising: (1) removing light components from the phenol-ketone tar to obtain a light-removed material; (2) adding a cracking catalyst and water to the light-removed material, and performing a cracking reaction under a pressure higher than one atmosphere and at a temperature higher than room temperature to obtain a cracking product. The phenol-ketone tar is a by-product heavy component tar produced in the production of phenol and acetone by cumene method, and contains phenol, acetophenone, α-methyl styrene dimer, 2-cumyl phenol, 4-cumyl phenol, and heavy oil. The cracking reaction pressure is 1-8 MPa. The amount of water added in step (2) is 0.5-4% by weight, based on the weight of the light-removed material. 2.The method of claim 1, wherein the removal of light components from the phenol-ketone tar is to remove phenol and acetophenone from the phenol-ketone tar, and the light components contain phenol and acetophenone, and the light-removed material contains α-methyl styrene dimer, 2-cumyl phenol, 4-cumyl phenol, and heavy oil. 3.The method of claim 1, wherein the removal of light components is performed by a negative pressure rectification device. 4.The method of claim 3, wherein the negative pressure rectification device has a theoretical plate number of 2-25, a pressure of 1-20 KPa, and a reflux ratio of 0.1-2. 5.The method of claim 3, wherein the negative pressure rectification device has a theoretical plate number of 5-20, a pressure of 2-10 KPa, and a reflux ratio of 0.5-1.

5. 6.The method of claim 1, wherein the light components contain phenol and acetophenone, and the light components are separated to obtain phenol and acetophenone, respectively. 7.The method of claim 6, wherein the light components are separated by at least two rectification separation devices to obtain phenol and acetophenone, respectively. 8.The method of claim 7, wherein the at least two rectification separation devices comprise a first rectification device and a second rectification device, and the first rectification device has a theoretical plate number of 20-120, a pressure of 50-150 KPa, and a reflux ratio of 2-25, and the second rectification device has a theoretical plate number of 10-120, a pressure of 0.5-15 KPa, and a reflux ratio of 0.1-8. 9.The method of claim 7, wherein the at least two rectification separation devices comprise a first rectification device and a second rectification device, and the first rectification device has a theoretical plate number of 30-100, a pressure of 60-130 KPa, and a reflux ratio of 3-20, and the second rectification device has a theoretical plate number of 20-80, a pressure of 1-10 KPa, and a reflux ratio of 0.5-5.

10. The method of claim 1, wherein, The cracking reaction temperature is 200-450 ℃.

11. The method of claim 1, wherein, The cracking reaction temperature is 230-400 ℃.

12. The method of claim 1, wherein, The cracking reaction temperature is 260-350 ℃.

13. The method of claim 1, wherein, The cracking reaction time is 1-25 h.

14. The method of claim 1, wherein, The cracking reaction time is 2-20 h.

15. The method of claim 1, wherein, The cracking reaction time is 3-15 h. 16.The method of claim 1, wherein the cracking is performed by a high-pressure reaction device. 17.The method of claim 16, wherein the high-pressure reaction device is selected from a high-pressure reaction kettle, a fixed bed reactor, a micro-channel reactor, and a tubular reactor.

18. The method of claim 1, wherein the cleavage catalyst is selected from the group consisting of alkali catalysts, acid catalysts.

19. The method of claim 1, wherein the cleavage catalyst is selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, formic acid, acetic acid, hydrochloric acid, boric acid, phosphoric acid, sulfuric acid, solid acid, solid base.

20. The method of claim 1, wherein the catalyst is used in an amount of 0.1-5 wt% based on the weight of the light-removed material.

21. The method of claim 1, wherein the catalyst is used in an amount of 0.5-4 wt% based on the weight of the light-removed material.

22. The method of claim 1, wherein the catalyst is used in an amount of 1-3 wt% based on the weight of the light-removed material.

23. The method of claim 1, wherein the cleavage product comprises cumene, phenol, ethylbenzene, and the method further comprises separating the cleavage product to obtain ethylbenzene, cumene, and phenol products, respectively.

24. The method of claim 23, wherein the cleavage product is separated by at least three rectification separation devices to obtain ethylbenzene, cumene, and phenol products, respectively.

25. The method of claim 24, wherein the at least three rectification separation devices comprise a third rectification device, a fourth rectification device, and a fifth rectification device.

26. The method of claim 25, wherein the third rectification device has a theoretical plate number of 30-80, a pressure of 3-25 Kpa, and a reflux ratio of 0.5-10; the fourth rectification device has a theoretical plate number of 30-80, a pressure of 3-25 Kpa, and a reflux ratio of 0.2-5; and the fifth rectification device has a theoretical plate number of 30-80, a pressure of 3-25 Kpa, and a reflux ratio of 0.5-10.

27. The method of claim 25, wherein the third rectification device has a theoretical plate number of 50-70, a pressure of 5-20 Kpa, and a reflux ratio of 1-8; the fourth rectification device has a theoretical plate number of 30-50, a pressure of 5-20 Kpa, and a reflux ratio of 0.5-3; and the fifth rectification device has a theoretical plate number of 30-50, a pressure of 5-20 Kpa, and a reflux ratio of 0.5-3.

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