Production system and method for co-producing cyclohexanone and cyclohexene oxide

Abstract

The invention provides a production system and method for co-producing cyclohexanone and cyclohexene oxide, and the system comprises a reactor, a slurry separator, a drying tower, a first rectifying tower, a second rectifying tower, a dehydrogenation reactor, a gas-liquid separation tank and a third rectifying tower which are sequentially connected according to production processes, a tower top discharge port of the drying tower is connected back to an upper feed port of the reactor, and a lower discharge port of the slurry separator is connected back to the reactor. According to the system and the method, cyclohexane and cyclohexene are used as raw materials, air is used as an oxygen source, and a mixture of cyclohexene oxide, cyclohexanone and cyclohexanol is generated through reaction under the catalysis condition of a nano-catalyst; and after cyclohexane and cyclohexene oxide are separated from the mixture through a rectifying tower, cyclohexanol enters a dehydrogenation reactor to generate cyclohexanone, and co-production of cyclohexanone and cyclohexene oxide is realized.

Description

Technical Field

[0001] This invention relates to the field of chemical product preparation, and in particular to a production system and method for co-producing cyclohexanone and cyclohexane oxide. Background Technology

[0002] Currently, in the industrial process of preparing cyclohexanone from cyclohexane by oxidation, cyclohexane is first oxidized to cyclohexylhydrogen peroxide. Cyclohexylhydrogen peroxide decomposes under certain pH conditions and with a catalyst to produce cyclohexanone and cyclohexanol. Cyclohexane oxide is produced as a byproduct in this process, but its selectivity and yield are very low. Cyclohexane oxide is not only an important intermediate in organic synthesis, used to prepare adipic acid, catechol, the pesticide chlorpyrifos, polycarbonate, and adipaldehyde, but also as a plasticizer, diluent, and curing agent for polymer materials. It is also a highly effective organic solvent. Furthermore, the presence of highly reactive epoxy groups in the cyclohexane oxide molecule allows it to react with ammonia, amines, phenols, alcohols, and carboxylic acids to generate a series of high-value-added compounds.

[0003] Currently, cyclohexane oxide is usually produced by the oxidation of cyclohexene, which can be roughly divided into chlorohydrin epoxidation, organic peroxy acid epoxidation, molecular oxygen epoxidation, hydrogen peroxide epoxidation, and electrochemical oxidation.

[0004] CN118084829A discloses a method for preparing cyclohexane oxide using a mixture from the hydrogenation reaction of benzene as a raw material. The reaction mixture contains benzene, cyclohexane, and cyclohexene. However, this reaction still uses cyclohexene as a raw material and hydrogen peroxide as an oxidant. Cyclohexane exists only as a solvent in this process and is not used as a reactant. CN100436435C discloses a method for preparing 1,2-cyclohexane oxide using cyclohexane. This method uses cyclohexane as a raw material, first oxidizing cyclohexane to cyclohexyl hydrogen peroxide, then adding cyclohexene to generate cyclohexane oxide and cyclohexanol. Cyclohexanol is dehydrated to produce cyclohexene, which is then recycled. However, this method has a single-pass conversion rate of only 3-5% when reacting air and cyclohexane. A large amount of cyclohexane enters the cyclohexene epoxidation reactor, diluting the reactant concentration, resulting in a low reaction rate, low conversion rate, and many byproducts. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a production system and method for co-producing cyclohexanone and cyclohexane oxide. The method uses cyclohexane and cyclohexene as raw materials, air as the oxygen source, and a nanocatalyst to react and generate a mixture of cyclohexane oxide, cyclohexanone, and cyclohexanol. After separating cyclohexane and cyclohexane oxide from the mixture via a distillation column, the cyclohexanol enters a dehydrogenation reactor to generate cyclohexanone, thus achieving the co-production of cyclohexanone and cyclohexane oxide.

[0006] A production system for co-producing cyclohexanone and cyclohexane oxide includes a reactor, a slurry separator, a drying tower, a first distillation tower, a second distillation tower, a dehydrogenation reactor, a gas-liquid separator, and a third distillation tower connected sequentially in the production process. The bottom outlet of the third distillation tower is connected back to the second distillation tower, the top outlet of the drying tower is connected back to the upper inlet of the reactor, and the lower outlet of the slurry separator is connected back to the reactor.

[0007] Preferably, the top outlet of the drying tower is connected to a phase separator.

[0008] Preferably, a condenser is provided between the dehydrogenation reactor and the gas-liquid separator.

[0009] The present invention also discloses a method for co-producing cyclohexanone and cyclohexane oxide using the above-mentioned production system. The raw materials of the method include air, cyclohexene, cyclohexane and nano-catalyst, wherein the molar ratio of cyclohexane to cyclohexene is 1:0.2 to 0.6, the mass ratio of cyclohexane to air is 1:1.1 to 1.8, and the mass ratio of cyclohexane to catalyst is 1:0.01 to 0.1.

[0010] Preferably, the nanocatalyst is a titanium-silicon molecular sieve supported in one or more forms of gold, silver, palladium or their oxides, with a metal loading ratio of 0.1% to 8 wt% and a pore size of 5 to 20 nm.

[0011] Preferably, the process conditions of the reactor are: temperature 110℃~280℃, pressure 0.4MPa~4MPa, and residence time 0.5h~6h.

[0012] Preferably, the reactants enter the slurry separator, and after the nanocatalyst and reaction products settle and separate, the slurry is discharged from the bottom of the separator and returned to the reactor for recycling via a circulation pump.

[0013] Preferably, the top of the first distillation column contains cyclohexane and cyclohexene, with a ratio of cyclohexane to cyclohexene of 1:0.01 to 0.1, which are then returned to the reactor for further reaction.

[0014] The beneficial effects of this invention are as follows: This invention enables the co-production of cyclohexane and cyclohexene from cyclohexane and cyclohexene oxide. Cyclohexene oxide is no longer a byproduct of the alkyl-to-ketone process but is instead produced as a product. The final yield of cyclohexene oxide reaches 20–40%, and the final yield of cyclohexane reaches 50–80%. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural diagram of the co-production system for cyclohexanone and cyclohexane oxide.

[0017] The components are as follows: 1. Reactor; 2. Slurry separator; 3. Catalyst circulation pump; 4. Drying tower; 5. Phase separator; 6. First distillation tower; 7. Second distillation tower; 8. Dehydrogenation reactor; 9. Condenser; 10. Gas-liquid separator; 11. Third distillation tower; 12. Vent tail gas; 13. Reaction liquid; 14. Circulating catalyst; 15. Reaction product; 16. Distillate from the drying tower; 17. Bottom liquid from the drying tower; 18. Oil phase; 19. Aqueous phase; 20. Distillate from the first distillation tower; 21. Bottom liquid from the first distillation tower; 22. Distillate from the second distillation tower; 23. Side stream from the second distillation tower; 24. Bottom liquid from the second distillation tower; 25. Hydrogen; 26. Dehydrogenation product; 27. Distillate from the third distillation tower; 28. Bottom liquid from the third distillation tower; 29. ​​Cyclohexane; 30. Cyclohexene; 31. Air. Detailed Implementation

[0018] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0020] Example 1: like Figure 1 As shown, the addition rate of cyclohexane 29 is 3828 kg / h, the addition rate of cyclohexene 30 is 1600 kg / h, and the introduction rate of air 31 is 4180 Nm. 3The flow rate of circulating cyclohexane (oil phase 18) is 34560 kg / h, which is added to reactor 1. The reaction temperature in reactor 1 is 140℃, the reaction pressure is 1.5 MPa, the catalyst concentration is controlled at approximately 0.12%, the residence time of the material in the reactor is controlled at 1 h, and the oxygen concentration in the vent gas 12 is controlled at 0.3%. The reaction liquid 13 enters slurry separator 2, where the catalyst and reaction product settle and separate, and are discharged from the bottom of the slurry separator. The circulating catalyst 14 is then pumped back to the reactor for recycling via catalyst circulation pump 3. The reaction product 15 enters drying tower 4.

[0021] The catalyst used in the reaction was a gold-supported titanium-silicon molecular sieve with a gold content of 0.77 wt% and a TiO2 content of 14.5%. The pore size of the nanocatalyst was 6–10 nm.

[0022] The top pressure of drying tower 4 is controlled at 4 kPag, the top temperature at 81℃, and the bottom temperature at 155℃. The distillate 16 (mainly water and cyclohexane) enters the phase separator 5 for oil-water separation. The oil phase 18, mainly composed of cyclohexane, is returned to reactor 1, while the aqueous phase 19 enters the wastewater treatment system at a flow rate of 220 kg / h. The bottom liquid 17 of the drying tower mainly consists of cyclohexane oxide, cyclohexanol, and cyclohexanone in a ratio of 28:53:19. The bottom liquid 17 of the drying tower enters the first distillation tower 6. The top pressure of the first distillation column 6 is -80 kPag, the top temperature is 85℃, and the bottom temperature is 115℃. The distillate 20 from the first distillation column is 99% cyclohexane oxide with a flow rate of 1805 kg / h. The bottom liquid 21 of the first distillation column mainly consists of cyclohexanol and cyclohexanone, with an alcohol-to-ketone ratio of 2.8:1. The bottom liquid 21 of the first distillation column is mixed with the bottom liquid 28 of the third distillation column (a mixture of cyclohexanol and cyclohexanone) and then enters the second distillation column 7. The total feed rate is approximately 11192 kg / h. The second distillation column 7 has a top pressure of -90 kPag, a top temperature of 69℃, and a bottom temperature of 102℃. The distillate 22 from the second distillation column is 99.9% cyclohexanone, with a flow rate of approximately 4468 kg / h. The bottom liquid 24 from the second distillation column is a heavy component, with a flow rate of approximately 60 kg / h. The side stream 23 from the second distillation column is cyclohexanol containing a small amount of cyclohexanone, with a cyclohexanol content of 96%, and enters the dehydrogenation reactor 8. The temperature of the dehydrogenation reactor 8 is 230℃, and the reaction pressure is 0.1 MPag. The reaction product is condensed by condenser 9 and then enters the gas-liquid separator 10, where hydrogen gas 25 is flashed off at the top at a flow rate of 745 Nm³. 3The liquid phase of the gas-liquid separator 10, consisting of dehydrogenation product 26, enters the third distillation column 11. The top pressure of the third distillation column 11 is -50 kPag, the top temperature is 110℃, and the bottom temperature is 131℃. The distillate 27 from the third distillation column is a light component with a flow rate of 20 kg / h. The bottom liquid 28 of the third distillation column is a mixture of cyclohexanol and cyclohexanone, with a ratio of approximately 1:1.05. The bottom liquid 28 of the third distillation column is mixed with the bottom liquid 21 of the first distillation column and then enters the second distillation column 7.

[0023] The conversion rate of cyclohexane in this unit is 9.5%, and the conversion rate of cyclohexene is 93%. The main products are cyclohexanone and cyclohexene oxide, with a yield of 27% for cyclohexene oxide and a yield of 67.5% for cyclohexanone.

[0024] Example 2: The addition rate of cyclohexane 29 is 3970 kg / h, the addition rate of cyclohexene 30 is 1356 kg / h, and the introduction rate of air 31 is 3970 Nm. 3 The flow rate of circulating cyclohexane (oil phase 18) is 48058 kg / h, which is added to reactor 1. The reaction temperature in reactor 1 is 130℃, the reaction pressure is 1.5 MPa, the catalyst concentration is controlled at approximately 0.13%, the residence time of the material in the reactor is controlled at 1.2 h, and the oxygen concentration in the tail gas 12 is controlled at 0.3%. The reaction liquid 13 enters slurry separator 2, where the catalyst and reaction product settle and separate, and are discharged from the bottom of the slurry separator. The circulating catalyst 14 is then pumped back to the reactor for recycling via catalyst circulation pump 3. The reaction product 15 enters drying tower 4.

[0025] The catalyst used in the reaction was a silver-supported titanium-silicon molecular sieve with a silver content of 3.6 wt% and a TiO2 content of 3.5% by mass. The pore size of the nanocatalyst was 15–25 nm.

[0026] The top pressure of drying tower 4 is controlled at 4 kPag, the top temperature at 80.5℃, and the bottom temperature at 154℃. The distillate 16 (mainly water and cyclohexane) enters the phase separator 5 for oil-water separation. The oil phase 18, mainly composed of cyclohexane, is returned to reactor 1, while the water phase 19 enters the wastewater treatment system at a flow rate of 155 kg / h. The bottom liquid 17 of the drying tower mainly consists of cyclohexane oxide, cyclohexanol, and cyclohexanone in a ratio of 22:61:13. The bottom liquid 17 of the drying tower enters the first distillation tower 6. The top pressure of the first distillation column 6 is -80 kPag, the top temperature is 85℃, and the bottom temperature is 117.2℃. The distillate 20 from the first distillation column is 99% cyclohexane oxide with a flow rate of 1635 kg / h. The bottom liquid 21 from the first distillation column mainly consists of cyclohexanol and cyclohexanone, with an alcohol-ketone ratio of 4.65:1. The bottom liquid 21 from the first distillation column is mixed with the bottom liquid 28 from the third distillation column and then enters the second distillation column 7. The total feed rate is approximately 12355 kg / h. The second distillation column 7 has a top pressure of -90 kPag, a top temperature of 69℃, and a bottom temperature of 104.5℃. The distillate 22 from the second distillation column is 99.9% cyclohexanone, with a flow rate of approximately 4630 kg / h. The bottom liquid 24 from the second distillation column is heavy components, with a flow rate of approximately 55 kg / h. The side stream 23 from the second distillation column is cyclohexanol, accounting for 95.7%, and enters the dehydrogenation reactor 8. The temperature of the dehydrogenation reactor is 230℃, and the reaction pressure is 0.1 MPag. The reaction product is condensed by condenser 9 and then enters the gas-liquid separator 10, where hydrogen 25 is flashed off at the top at a flow rate of 866 Nm³. 3 The liquid phase of the gas-liquid separator 10, consisting of dehydrogenation product 26, enters the third distillation column 11 at a flow rate of 18 kg / h. The top pressure of the third distillation column 11 is -50 kPag, the top temperature is 106°C, and the bottom temperature is 130.8°C. The distillate 27 from the third distillation column is a light component with a flow rate of 18 kg / h. The bottom liquid 28 from the third distillation column is a mixture of cyclohexanol and cyclohexanone, with a ratio of approximately 1.01:1. The bottom liquid 28 from the third distillation column is mixed with the bottom liquid 21 from the first distillation column and then enters the second distillation column 7.

[0027] The conversion rate of cyclohexane in this unit is 8%, and the conversion rate of cyclohexene is 95%. The main products are cyclohexanone and cyclohexene oxide, with a yield of 24.8% for cyclohexene oxide and 71% for cyclohexanone.

[0028] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A production system for the co-production of cyclohexanone and cyclohexane oxide, characterized in that, The system includes a reactor, a slurry separator, a drying tower, a first distillation tower, a second distillation tower, a dehydrogenation reactor, a gas-liquid separator, and a third distillation tower connected in sequence according to the production process. The bottom outlet of the third distillation tower is connected back to the second distillation tower, the top outlet of the drying tower is connected back to the upper inlet of the reactor, and the lower outlet of the slurry separator is connected back to the reactor.

2. The production system for co-producing cyclohexanone and cyclohexane oxide according to claim 1, characterized in that, The top outlet of the drying tower is connected to a phase separator.

3. The production system for co-producing cyclohexanone and cyclohexane oxide according to claim 1, characterized in that, A condenser is installed between the dehydrogenation reactor and the gas-liquid separator.

4. A method for co-producing cyclohexanone and cyclohexane oxide using the production system according to any one of claims 1 to 4, characterized in that, The raw materials for this method include air, cyclohexene, cyclohexane, and nano-catalyst, wherein the molar ratio of cyclohexane to cyclohexene is 1:0.2 to 0.6, the mass ratio of cyclohexane to air is 1:1.1 to 1.8, and the mass ratio of cyclohexane to catalyst is 1:0.01 to 0.

1.

5. The method for co-producing cyclohexanone and cyclohexane oxide using the production system according to claim 4, characterized in that, The nanocatalyst is a titanium-silicon molecular sieve supported in one or more forms of gold, silver, palladium or their oxides, with a metal loading ratio of 0.1% to 8 wt% and a pore size of 5 to 20 nm.

6. The method for co-producing cyclohexanone and cyclohexane oxide using the production system according to claim 4, characterized in that, The process conditions of the reactor are: temperature 110℃~280℃, pressure 0.4MPa~4MPa, residence time 0.5h~6h.

7. The method for co-producing cyclohexanone and cyclohexane oxide using the production system according to claim 4, characterized in that, The reactants enter the slurry separator. After the nanocatalyst and reaction products settle and separate, the slurry is discharged from the bottom of the separator and returned to the reactor for recycling via a circulation pump.

8. The method for co-producing cyclohexanone and cyclohexane oxide using the production system according to claim 4, characterized in that, The top of the first distillation column contains cyclohexane and cyclohexene in a ratio of 1:0.01 to 0.1, which are then returned to the reactor to continue the reaction.

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