Rectification device for separating m-cresol and p-cresol

Abstract

The utility model discloses a rectification device for separating m-cresol and p-cresol. The rectification device comprises a dealkylation reactor, a first flash tank, a second flash tank and a rectification tower, a feeding pipeline is mounted at a feeding hole of the dealkylation reactor, and a discharging pipeline is mounted at a discharging hole of the dealkylation reactor; a feed port of the first flash tank is connected with one end of the discharge pipeline, communicating pipelines are mounted at the bottoms of the first flash tank and the second flash tank, and compression recovery assemblies for compressing and recovering reaction products are mounted at the tops of the first flash tank and the second flash tank; an advanced dealkylation reaction process and a reflux process section design thereof are adopted, so that high-purity separation of m-cresol and p-cresol and efficient recovery of a byproduct isobutene can be realized, a very small amount of isobutene of p-cresol or m-cresol which is not separated can be circularly rectified, the waste of p-cresol or m-cresol and isobutene is reduced, and the production cost is reduced. The purity and the yield of the product are improved, the energy consumption and the production cost are reduced, and the method has a wide application prospect.

Description

Technical Field

[0001] This utility model relates to the field of distillation simulation technology, and in particular to a distillation apparatus for separating m-p-cresol. Background Technology

[0002] In the field of fine chemicals, phenolic compounds, especially m-cresol and p-cresol, are widely used in various industries such as pesticides, dyes, fragrances, and pharmaceutical synthesis due to their unique chemical properties. m-cresol plays a crucial role as a pesticide intermediate in the synthesis of insecticides; it is also an important raw material for the preparation of color films, resins, and plasticizers. p-cresol is a key intermediate in the synthesis of many drugs, playing a vital role in the production of the antibacterial drug chloramphenicol. Furthermore, p-cresol can also be used to synthesize fragrances and antioxidants.

[0003] Crude phenol, a byproduct of coal chemical industry, contains various phenolic compounds, including phenol, o-cresol, m-cresol, p-cresol, and xylenol. These phenolic compounds are highly economical and valuable fine chemical raw materials. However, refining high-purity m-cresol and p-cresol from crude phenol presents a technical challenge. This is because m-cresol and p-cresol have very similar boiling points (202.3℃ and 201.8℃, respectively), making it difficult for conventional distillation equipment and processes to effectively separate and purify them, thus failing to meet the quality requirements of downstream applications.

[0004] To overcome the technical challenges, researchers have explored various separation methods, including complexation separation (such as urea adsorption separation), distribution crystallization, and physical separation. While these methods can achieve separation of m-cresol and p-cresol to some extent, they generally suffer from problems such as high operational difficulty, low product purity, high energy consumption, low throughput, and significant environmental pollution. Consequently, they lack industrial application value and fail to achieve large-scale industrial application.

[0005] Therefore, existing m-p-cresol separation technologies have many shortcomings, and a high-efficiency, energy-saving distillation device that can improve product quality is needed. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a distillation apparatus for separating m-p-cresol.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a distillation apparatus for separating m-p-cresol, comprising: a dealkylation reactor, a first flash tank, a second flash tank, and a distillation column;

[0008] The dealkylation reactor has a feed inlet and a discharge outlet; the feed inlet of the first flash tank is connected to one end of the discharge outlet; the bottom of both the first and second flash tanks is connected to a connecting pipe, and the top of both tanks is equipped with a compression and recovery assembly for compressing and recovering the reaction products.

[0009] One end of the connecting pipe at the bottom of the first flash tank is connected to the inlet of the second flash tank, and one end of the connecting pipe at the bottom of the second flash tank is connected to the inlet of the distillation column; a discharge pipe is installed at the outlet of the distillation column, a by-product pipe is installed at the bottom of the column, and a reflux pipe is installed at the top of the column; one end of the reflux pipe is connected to the inlet of the first flash tank.

[0010] In a preferred embodiment of this utility model, the distillation column has 12-14 trays, and the feed tray of the distillation column inlet is located on the 6th-7th tray.

[0011] In a preferred embodiment of the present invention, the compression and recovery assembly includes: a recovery pipeline installed on the top of the first flash tank and the second flash tank, and a compressor installed on the recovery pipeline.

[0012] In a preferred embodiment of this invention, a heater for preheating the raw materials is installed on the feed pipe.

[0013] In a preferred embodiment of this utility model, both the discharge pipeline and the return pipeline are equipped with coolers for cooling the material.

[0014] This utility model solves the defects existing in the background technology, and has the following beneficial effects:

[0015] (1) This utility model provides a distillation apparatus for separating m- and p-cresol. Through the cooperation of a dealkylation reactor, a first flash tank, a second flash tank and a distillation column, an advanced dealkylation reaction process and its reflux process section design are adopted. This can achieve high-purity separation of m- and p-cresol and efficient recovery of the by-product isobutylene. At the same time, with the cooperation of the reflux pipeline, the very small amount of isobutylene that was not separated from p- or m-cresol can be recycled and distilled, which can reduce the waste of p- or m-cresol and isobutylene. This not only improves the purity and yield of the product, but also reduces energy consumption and production costs, and has broad application prospects. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0017] Figure 1 This is a schematic diagram of the overall structure of a preferred embodiment of the present invention;

[0018] In the diagram: 1. Dealkylation reactor; 11. Feed line; 12. Discharge line; 2. First flash tank; 3. Second flash tank; 4. Distillation column; 41. Discharge line; 42. By-product line; 43. Reflux line; 5. Connecting line; 6. Recovery line; 61. Compressor; 7. Heater; 8. Cooler. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0020] like Figure 1 As shown, a distillation apparatus for separating m-p-cresol includes: a dealkylation reactor 1, a first flash tank 2, a second flash tank 3, and a distillation column 4; the inlet of the dealkylation reactor 1 is equipped with a feed pipe 11, and the outlet is equipped with a discharge pipe 12; the inlet of the first flash tank 2 is connected to one end of the discharge pipe 12, and both the bottom of the first flash tank 2 and the second flash tank 3 are equipped with connecting pipes 5, and the top of both tanks are equipped with compression and recovery components for compressing and recovering reaction products; one end of the connecting pipe 5 at the bottom of the first flash tank 2 is connected to the inlet of the second flash tank 3, and one end of the connecting pipe 5 at the bottom of the second flash tank 3 is connected to the inlet of the distillation column 4; the outlet of the distillation column 4 is equipped with a discharge pipe 41, the bottom of the column is equipped with a by-product pipe 42, and the top of the column is equipped with a reflux pipe 43; one end of the reflux pipe 43 is connected to the inlet of the first flash tank 2.

[0021] It should be noted that the distillation column 4 has 12-14 trays, and the feed tray at the feed inlet of the distillation column 4 is located on the 6th-7th tray. The raw material enters the dealkylation reactor 1 through the feed pipe 11. A specific chemical reaction occurs in the reactor, converting the alkyl compounds in the raw material into cresol. The cresol mixture after the dealkylation reaction enters the first flash tank 2 through the discharge pipe 12. The flash tank reduces the pressure to rapidly vaporize part of the liquid, achieving preliminary separation. The vaporized part is mainly the light component, while the remaining liquid is rich in the heavier cresol. The bottom product of the first flash tank 2 enters the second flash tank 3 through the connecting pipe 5 for further separation. The isobutylene produced by the reaction is compressed and recovered by the compression and recovery component. The bottom product of the second flash tank 3 enters the distillation column 4, where multiple partial vaporization and condensation are achieved through multi-stage trays. Utilizing the differences in the distribution of different components on the trays, efficient separation is achieved. Finally, m- and p-cresol are discharged from the top or bottom of the column, while the by-products are discharged from another outlet. The reflux pipeline 43 set at the top of the distillation column 4 sends the incompletely separated material back to the first flash tank 2 for recycling and reflux operation to improve the purity and recovery rate of the product. By optimizing the process flow and equipment design, efficient separation of m-cresol and p-cresol, which have similar boiling points, can be achieved. This not only improves the purity and yield of the product but also reduces energy consumption and production costs, showing broad application prospects.

[0022] In some embodiments, the compression and recovery assembly includes: a recovery pipeline 6 installed on the top of the first flash tank 2 and the second flash tank 3, and a compressor 61 installed on the recovery pipeline 6; the recovery pipeline 6 is used to draw out gases such as isobutylene generated during the flash evaporation process, and the compressor 61 compresses the gas in the recovery pipeline 6 to increase the pressure and temperature of the gas, which can efficiently recover the isobutylene generated during the flash evaporation process and avoid resource waste.

[0023] In some embodiments, a heater 7 for preheating the raw materials is installed on the feed line 11; by installing the heater 7 on the feed line 11, the raw materials can be preheated, which can accelerate the reaction rate, make the dealkylation reaction more efficient, and thus increase the yield and purity of the product.

[0024] In some embodiments, coolers 8 for cooling materials are installed on both the discharge pipe 12 and the return pipe 43. By installing coolers 8 on the discharge pipe 12 and the return pipe 43, the materials can be cooled, which helps to stabilize the properties of the materials and prevent unnecessary chemical reactions in subsequent processes. At the same time, cooling can also reduce the temperature of the materials, making them more suitable for subsequent processing or storage.

[0025] Example 1

[0026] Step 1: Select 2,6-di-tert-butyl-p-cresol generated by the alkylation reaction as the feed material, with a feed rate of 800 kg / h. It enters the dealkylation reactor 1 through the feed pipeline 11. The temperature inside the dealkylation reactor 1 is set to 180℃ and the pressure to 1.5 bar. The dealkylation reaction occurs, and the material is cooled to 50℃ through the discharge pipeline 12 and the cooler 8.

[0027] Step 2: The 391 kg / h p-cresol, 406 kg / h isobutylene, and 3 kg / h 2-tert-butyl-p-cresol generated in the reaction are flashed twice through the first flash tank 2 and the second flash tank 3 respectively through the connecting pipeline 5. Then, the isobutylene generated in the reaction is compressed and recovered through the recovery pipeline 6 and the compressor 61, with a mass fraction of 99.2%.

[0028] Step 3: The remaining isobutylene (0.8% by mass), p-cresol (391 kg / h), and 2-tert-butyl-p-cresol (3 kg / h by mass) are fed into distillation column 4 via the connecting pipe 5 at the bottom of the second flash tank 3 for distillation separation. Distillation column 4 has 14 trays, with the feed tray being the 7th tray. The reflux ratio is 2.5, the diameter is 0.85 m, and the packing height is 10.8 m. Dixon packing is used. After distillation separation, the product can be discharged from the outlet of distillation column 4. The discharge line 41 yields high-purity p-cresol with a purity of 99.5%. The remaining small amount of p-cresol and the 2-tert-butyl-p-cresol generated in the reaction flow out from the by-product line 42 at the bottom of the tower. In addition, the p-cresol that was not separated from the discharge line 41 and a very small amount of isobutylene are cooled to 50°C by the cooler 8 through the reflux line 43. They are then reintroduced into the first flash tank 2 along with the new components generated in the dealkylation reactor 1 to repeat the process, thereby reducing the waste of isobutylene and p-cresol.

[0029] Example 2

[0030] This embodiment is basically the same as Embodiment 1, except that the design of the distillation column 4 is different:

[0031] Step 1: Select 4,6-di-tert-butyl-m-cresol generated by alkylation as the feed material, with a feed rate of 1200 kg / h. It enters the dealkylation reactor 1 through the feed pipeline 11. The temperature inside the dealkylation reactor 1 is set to 180℃ and the pressure to 1.5 bar. The dealkylation reaction occurs, and the material is cooled to 50℃ through the discharge pipeline 12 and the cooler 8.

[0032] Step 2: The 586 kg / h m-cresol, 610 kg / h isobutylene, and 4 kg / h 6-tert-butyl-m-cresol generated in the reaction are flashed twice through the first flash tank 2 and the second flash tank 3 respectively through the connecting pipeline 5. Then, the isobutylene generated in the reaction is compressed and recovered through the recovery pipeline 6 and the compressor 61, which has a mass fraction of 99.2%.

[0033] Step 3: The remaining isobutylene (0.8% by mass), m-cresol (586 kg / h), and 6-tert-butyl-m-cresol (4 kg / h) are fed into distillation column 4 via the connecting pipe 5 at the bottom of the second flash tank 3 for distillation separation. Distillation column 4 has 12 trays, with the feed tray being the 6th tray. The reflux ratio is 2.6, the diameter is 0.75 m, and the packing height is 9 m, using Dixon packing. After distillation separation, the product can be discharged from the outlet of distillation column 4. Feed line 41 yields high-purity m-cresol with a purity of 99.5%. The remaining small amount of m-cresol and the 6-tert-butyl-m-cresol generated in the reaction flow out from the by-product line 42 at the bottom of the tower. In addition, the m-cresol that was not separated from the discharge line 41 and a very small amount of isobutylene are cooled to 50°C by the cooler 8 through the reflux line 43. Together with the new components generated by the dealkylation reactor 1, they are reintroduced into the first flash tank 2 to repeat this process, thereby reducing the waste of isobutylene and p-cresol.

[0034] Based on the above description and the preferred embodiments of this utility model, it will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0035] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A distillation apparatus for separating m-p-cresol, characterized in that, include: The dealkylation reactor (1), the first flash tank (2), the second flash tank (3), and the distillation column (4) are included. The dealkylation reactor (1) is equipped with a feed pipe (11) at its inlet and a discharge pipe (12) at its outlet; the inlet of the first flash tank (2) is connected to one end of the discharge pipe (12); both the first flash tank (2) and the second flash tank (3) are equipped with connecting pipes (5) at their bottoms and compression and recovery components for compressing and recovering reaction products at their tops; One end of the connecting pipe (5) at the bottom of the first flash tank (2) is connected to the inlet of the second flash tank (3), and one end of the connecting pipe (5) at the bottom of the second flash tank (3) is connected to the inlet of the distillation column (4); the outlet of the distillation column (4) is equipped with a discharge pipe (41), the bottom of the column is equipped with a by-product pipe (42), and the top of the column is equipped with a reflux pipe (43); one end of the reflux pipe (43) is connected to the inlet of the first flash tank (2).

2. A distillation apparatus for separating m-p-cresol according to claim 1, characterized in that: The distillation column (4) has 12-14 trays, and the feed tray of the feed inlet of the distillation column (4) is located on the 6th-7th tray.

3. A distillation apparatus for separating m-p-cresol according to claim 1, characterized in that: The compression and recovery assembly includes: a recovery pipeline (6) installed on the top of the first flash tank (2) and the second flash tank (3), and a compressor (61) installed on the recovery pipeline (6).

4. A distillation apparatus for separating m-p-cresol according to claim 1, characterized in that: A heater (7) for preheating the raw materials is installed on the feed pipe (11).

5. A distillation apparatus for separating m-p-cresol according to claim 1, characterized in that: Coolers (8) for cooling materials are installed on both the discharge pipe (12) and the return pipe (43).

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