Method for preparing cyclohexanol from byproduct X oil in cyclohexanone production process by hydration method

Abstract

The invention relates to the technical field of X oil recovery, and discloses a method for preparing cyclohexanol from a byproduct X oil in a cyclohexanone production process by a hydration method. The method comprises the following steps: (1) in the presence of hydrogen, introducing mixed reaction oil containing X oil and an organic solvent into a fixed bed reactor filled with a hydrogenation catalyst, and carrying out hydrotreatment to obtain a hydrotreatment effluent; (2) introducing the hydrotreating effluent into a desolventizing tower for first separation to obtain hydrogenated X oil and an organic solvent which can be recycled to the step (1); and (3) introducing the hydrogenated X oil into a cyclohexanol recovery tower for secondary separation to obtain gas-phase cyclohexanol and heavy X oil. According to the method provided by the invention, phenol in the X oil can be hydrogenated into cyclohexanol, efficient separation is carried out, effective utilization of phenol in the X oil is realized, and material loss in the production process is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of X oil recovery, and in particular to a method for preparing cyclohexanol from X oil, a by-product in a cyclohexanone production process using a hydration method. Background Art

[0002] Cyclohexanol is an important chemical raw material, mainly used in the production of adipic acid, hexamethylenediamine, cyclohexanone, and caprolactam. It can also be used as a soap stabilizer to manufacture disinfectant soaps and detergent emulsions. It is an excellent medium-to-high boiling point organic solvent and the main intermediate raw material for the production of caprolactam or adipic acid.

[0003] Compared with the cyclohexane oxidation production process, the cyclohexene hydration method for producing cyclohexanol is increasingly recognized and applied due to its mature process technology, larger production capacity of a single unit, safer production process, and significantly lower production costs than the oxidation process.

[0004] The cyclohexene process for producing cyclohexanone consists of three main steps. The first, the benzene partial hydrogenation step, uses benzene as the raw material. Under the catalytic action of a catalyst at a certain temperature and pressure, benzene and hydrogen undergo a partial hydrogenation reaction to produce cyclohexene and some cyclohexane as a by-product. The second step, the benzene hydrogenation step, produces purified cyclohexene, which reacts with water at a certain temperature and pressure in the presence of a catalyst to produce cyclohexanol. The third step, the cyclohexene hydration step, produces purified cyclohexanol, which is then dehydrogenated to produce cyclohexanone under the presence of a catalyst under certain temperature and pressure conditions.

[0005] Impurities are generated during each reaction process. In the third cyclohexanol dehydrogenation process to produce cyclohexanone, cyclohexanol reacts with the dehydrogenation catalyst to produce not only the main product, cyclohexanone, but also a number of side reactions. Phenol accounts for 50-60% of the total side reaction. The heavy components produced by the dehydrogenation side reactions are then processed through the refining system and collected as X-oil, a low-value waste oil. However, the phenol content in X-oil exceeds 40%, resulting in significant material waste. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing cyclohexanol from the by-product X oil in the cyclohexanone production process by hydration.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing cyclohexanol from the by-product X oil in the cyclohexanone production process by hydration, the method comprising:

[0008] (1) In the presence of hydrogen, a mixed reaction oil containing X oil and an organic solvent is introduced into a fixed bed reactor filled with a hydrogenation catalyst for hydrogenation treatment to obtain a hydrogenation effluent;

[0009] (2) introducing the hydroprocessing effluent into a desolventizing tower for first separation to obtain hydrogenated X oil and an organic solvent that can be recycled to step (1);

[0010] (3) introducing the hydrogenated X oil into a cyclohexanol recovery tower for a second separation to obtain a cyclohexanol-containing gaseous effluent and heavy X oil;

[0011] The X oil contains 40-50 wt% phenol, 5-16 wt% cyclohexanol, and 5-10 wt% cyclohexanone; the viscosity of the X oil is 6-10 mm 2 / s;

[0012] In the mixed reaction oil, the volume ratio of the organic solvent to the X oil is 1-5:1;

[0013] The hydrogenation catalyst comprises a carrier and an active metal component; the active metal component is nickel; and based on the total mass of the hydrogenation catalyst, the content of the active metal component in terms of element is 20-30 wt%.

[0014] The method provided by the present invention can hydrogenate phenol in X oil to cyclohexanol and perform efficient separation, effectively utilizing the phenol in X oil and reducing material loss during the production process. Furthermore, the method provided by the present invention can significantly improve the conversion rate of phenol and the selectivity for cyclohexanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a method for preparing cyclohexanol from the cyclohexanone by-product X oil described in a preferred embodiment of the present invention.

[0016] Description of Reference Numerals

[0017] 1. X oil 2. Organic solvent 3. Mixed reaction oil 4. Hydrogen

[0018] 5. Unreacted hydrogen 6. Hydrogenated X oil 7. Gas effluent containing cyclohexanol

[0019] 8. Heavy X oil 9, 10, 11 are all water vapor 12, 13 are all desalted water

[0020] R1, fixed bed reactor C1, desolventizing tower C2, cyclohexanol recovery tower

[0021] E1, feed heater E2, desolventizing tower reboiler E3, desolventizing tower top cooler

[0022] E4, recovery tower reboiler P1, P2, P3 are shielded pumps

[0023] V1, premixer V2, desolventizing tower reflux tank DETAILED DESCRIPTION

[0024] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0025] As mentioned above, the first aspect of the present invention provides a method for preparing cyclohexanol from the by-product X oil in the cyclohexanone production process by hydration, the method comprising:

[0026] (1) In the presence of hydrogen, a mixed reaction oil containing X oil and an organic solvent is introduced into a fixed bed reactor filled with a hydrogenation catalyst for hydrogenation treatment to obtain a hydrogenation effluent;

[0027] (2) introducing the hydroprocessing effluent into a desolventizing tower for first separation to obtain hydrogenated X oil and an organic solvent that can be recycled to step (1);

[0028] (3) introducing the hydrogenated X oil into a cyclohexanol recovery tower for a second separation to obtain a cyclohexanol-containing gaseous effluent and heavy X oil;

[0029] The X oil contains 40-50 wt% phenol, 5-16 wt% cyclohexanol, and 5-10 wt% cyclohexanone; the viscosity of the X oil is 6-10 mm 2 / s;

[0030] In the mixed reaction oil, the volume ratio of the organic solvent to the X oil is 1-5:1;

[0031] The hydrogenation catalyst comprises a carrier and an active metal component; the active metal component is nickel; and based on the total mass of the hydrogenation catalyst, the content of the active metal component in terms of element is 20-30 wt%.

[0032] The present invention uses a specific type of hydrogenation catalyst to hydrogenate a mixed reaction oil containing an organic solvent and X oil in a volume ratio of 1-5:1, which can efficiently convert phenol in the X oil into cyclohexanol and significantly improve the conversion rate of phenol and the selectivity of cyclohexanol.

[0033] Preferably, the X oil is a heavy component from the bottom of a refined tower produced by dehydrogenating cyclohexanol to produce cyclohexanone.

[0034] Preferably, the X oil further contains cyclohexanone derivatives, and the content of the cyclohexanone derivatives is 30-40 wt%.

[0035] Preferably, the cyclohexanone derivative is at least one selected from 2-(1-cyclohexenyl)cyclohexanone, dicyclohexyl ether, and 2-cyclohexylcyclohexanone.

[0036] In the present invention, the contents of phenol, cyclohexanol and cyclohexanone derivatives in the X oil are determined by liquid chromatography. The viscosity of the X oil refers to the viscosity of the X oil at 40° C., which is determined using a viscometer.

[0037] Preferably, in step (1), the conditions of the hydrotreatment include: temperature of 130-150°C, pressure of 1.4-2.5 MPa, volume space velocity of 2.5-4.6 h -1 The inventors have found that under the preferred conditions, the hydrogenation reaction of the mixed reaction oil is more complete, resulting in a higher conversion rate of phenol in the X oil to cyclohexanol.

[0038] Preferably, in step (1), the volume ratio of the organic solvent to the X oil in the mixed reaction oil is 2-3:1. The inventors have found that under this preferred condition, the viscosity of the X oil can be reduced, preventing clogging and deactivation of the catalyst active sites, thereby further improving the conversion rate of phenol and the selectivity of cyclohexanol.

[0039] Preferably, the organic solvent is C 6-7 Saturated alkanes and / or C 6-7 The inventors found that under this preferred condition, the viscosity of the X oil can be more easily reduced, making the mixed reaction oil more easily subjected to the hydrogenation reaction, thereby improving the conversion rate of phenol in the X oil and the selectivity of cyclohexanol.

[0040] More preferably, the organic solvent is selected from at least one of cyclohexane, methylcyclopentane and methylcyclohexane.

[0041] Preferably, in step (1), the volume ratio of the hydrogen to the X oil is 400-500:1.

[0042] Preferably, in the hydrogenation catalyst, the carrier is selected from at least one of alumina and silica.

[0043] Preferably, based on the total mass of the hydrogenation catalyst, the content of the carrier is 70-80 wt % in terms of oxide.

[0044] Preferably, the fixed bed reactor is a random pile fixed bed reactor.

[0045] The present invention has no particular limitation on the flow rate and introduction method of the hydrogen. Known operations can be used. The present invention will not be described in detail here, and those skilled in the art should not understand this as a limitation on the present invention.

[0046] Preferably, in step (2), steam is used to heat the hydroprocessing effluent in the desolventizing tower.

[0047] Preferably, in step (2), the operating pressure of the desolventizing tower is 5-15 KPaG, the top temperature is 82-90°C, the bottom temperature is 150-160°C, the reflux ratio is 0.4-1:1, and the number of theoretical plates is 20-30.

[0048] Preferably, the hydrotreatment effluent is fed from the Nth theoretical plate of the desolventizing tower, where N is 10 to 12. The inventors have found that under this preferred condition, the yield and purity of cyclohexanol can be further improved.

[0049] Preferably, in step (3), water vapor is used to heat the hydrogenated X oil in the cyclohexanol recovery tower.

[0050] Preferably, in step (3), the operating pressure of the cyclohexanol recovery tower is 5-20 KPaA, the top temperature is 90-115° C., the bottom temperature is 120-135° C., and the number of theoretical plates is 20-30.

[0051] Preferably, the cyclohexanol-containing gaseous effluent is introduced into a cyclohexanone refining system for recovery.

[0052] In the present invention, the desolventizing tower and the cyclohexanol recovery tower are both structured packing towers.

[0053] According to a preferred embodiment, the method further comprises: before introducing the mixed reaction oil into the fixed bed reactor, preheating the mixed reaction oil to 120-140° C. by water vapor in a feed heater, and then introducing the preheated mixed reaction oil into the fixed bed reactor for the hydrogenation treatment.

[0054] Preferably, the preheating temperature is 5-10° C. lower than the hydrotreatment temperature. The inventors have found that under this preferred condition, the conversion rate of phenol and the selectivity of cyclohexanol can be further improved.

[0055] According to another preferred embodiment, the method further comprises: before the preheating, mixing the organic solvent and X oil to obtain the mixed reaction oil.

[0056] The present invention has no particular requirements for the mixing method and conditions, as long as the organic solvent and X oil can be uniformly mixed. The present invention will not be described in detail here, and those skilled in the art should not understand this as a limitation of the present invention.

[0057] The following combination Figure 1A preferred embodiment is provided to illustrate the method (process flow) for preparing cyclohexanol from by-product X oil in the hydration method cyclohexanone production process of the present invention:

[0058] like Figure 1 As shown, an organic solvent 2 and an X oil 1 are mixed in a premixer V1 to obtain a mixed reaction oil. The mixed reaction oil is preheated by water vapor 9 through a feed heater E1. Then, the preheated mixed reaction oil 3 and hydrogen 4 are introduced into a fixed-bed reactor R1 filled with a hydrogenation catalyst for hydrogenation treatment to obtain a hydrogenation effluent 4 and unreacted hydrogen 5. The reaction heat is removed from the bottom to the top of the shell of the fixed-bed reactor R1 by means of normal-temperature desalted water 12 (i.e., removed by the desalted water 13 after heat exchange) to control the bed temperature of the fixed-bed reactor R1.

[0059] The unreacted hydrogen 5 is introduced into the top of the desolventizing tower C1 from a position below the catalyst bed in the fixed bed reactor R1, and then cooled by the desolventizing tower top cooler E3 to obtain a cooled stream and hydrogen. The hydrogen is recovered, and the cooled stream is refluxed through the desolventizing tower reflux tank V2 and then pumped to the top of the desolventizing tower C1 by the second canned motor pump P2;

[0060] The hydroprocessing effluent 4 enters the desolventizing tower C1 from the bottom of the fixed bed reactor R1 under the action of pressure difference for first separation to obtain hydrogenated X oil 6 and organic solvent;

[0061] The organic solvent is introduced into the premixer V1 and recycled as a solvent. The hydrogenated X oil 6 flows out from the bottom of the desolventizing tower C1 and is pumped into the cyclohexanol recovery tower C2 via the first canned motor pump P1 for a second separation to obtain a cyclohexanol-containing gaseous effluent 7 and heavy X oil 8.

[0062] The cyclohexanol-containing gaseous effluent 7 is introduced from the top of the cyclohexanol recovery tower C2 into the original cyclohexanone refining system for recovery, and the heavy X oil 8 in the tower kettle is drawn out through the third shielded pump and disposed of as fuel oil.

[0063] The desolventizing tower reboiler E2 is used to heat the desolventizing tower C1, and the heat source of the desolventizing tower reboiler E2 is provided by water vapor 10; the recovery tower reboiler E4 is used to heat the cyclohexanol recovery tower C2, and the heat source of the recovery tower reboiler E4 is provided by water vapor 11.

[0064] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all raw materials used are commercially available.

[0065] X oil contains 43.65wt% phenol, 15.98wt% cyclohexanol, 9.73wt% cyclohexanone, and 30.64wt% cyclohexanone derivatives; the viscosity of the X oil is 8.03mm 2 / s.

[0066] Hydrogenation Catalyst I: The active metal component is nickel, and the carrier is alumina and silica. Based on the total mass of the hydrogenation catalyst, the content of the active metal component is 24 wt% as an element; the content of the carrier is 76 wt% as an oxide. The trade name is Risun-CHA-Ⅰ, and it is produced by Xuyang Technology Co., Ltd.

[0067] Hydrogenation catalyst II: The active component is nickel, and the carrier is silicon oxide and aluminum oxide. Based on the total mass of the hydrogenation catalyst, the content of the active metal component is 50wt% as an element; the content of the carrier is 50wt% as an oxide. The trade name is NCG-8, and it is produced by Xuyi Yongli Technology Co., Ltd.

[0068] Example 1

[0069] (1) Cyclohexane and oil X are mixed in a premixer to obtain a mixed reaction oil, the mixed reaction oil is preheated to a set temperature by steam in a feed heater, and then the preheated mixed reaction oil and hydrogen are introduced into a fixed bed reactor filled with 250 mL of hydrogenation catalyst I for hydrogenation treatment to obtain a hydrogenation effluent;

[0070] (2) The hydrotreatment effluent enters the desolventizing tower from the bottom of the fixed bed reactor R1 under the action of pressure difference for first separation to obtain hydrogenated X oil and an organic solvent; the organic solvent is introduced into the premixer V1 in step (1) and recycled as a solvent;

[0071] (3) The hydrogenated X oil flows out from the bottom of the desolventizing tower C1 and is pumped into the cyclohexanol recovery tower C2 through a shielded pump for secondary separation to obtain gaseous cyclohexanol and heavy X oil; the gaseous cyclohexanol is introduced from the top of the cyclohexanol recovery tower C2 into the original cyclohexanone refining system for recovery, and the heavy X oil in the bottom of the recovery tower is used as fuel oil for external disposal;

[0072] The process parameters of the mixing, preheating, hydrogenation, desolventizing tower and cyclohexanol recovery tower are shown in Table 1.

[0073] Examples 2 to 6, and Comparative Examples 1 to 2 were carried out using a method similar to that of Example 1, with the differences being the volume ratio of the organic solvent to the X oil, the type of catalyst, or the process parameters. Specific details are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] Table 1

[0078]

[0079] Test Case

[0080] Liquid chromatography was used to analyze and detect the products obtained in the above examples.

[0081] Among them, the conversion rate of phenol is calculated as follows:

[0082] Conversion rate of phenol = (molar fraction of phenol in raw material X oil - molar fraction of phenol in hydrogenated X oil) / molar fraction of phenol in raw material X oil × 100%

[0083] Cyclohexanol selectivity calculation formula:

[0084] Cyclohexanol selectivity = (cyclohexanol mole fraction in hydrogenated X oil - cyclohexanol mole fraction in raw X oil) / (phenol mole fraction in raw X oil - phenol mole fraction in hydrogenated X oil) × 100%

[0085] The results are shown in Table 2.

[0086] Table 2

[0087] Example No. Conversion rate of phenol / % Cyclohexanol selectivity / % Example 1 97.1 109.8 Example 2 95.4 106.4 Example 3 86.9 101.7 Example 4 91.8 105.3 Example 5 93.4 103.3 Example 6 95.8 105.4 Comparative Example 1 85.7 102.6 Comparative Example 2 74.9 101.8

[0088] The above results indicate that the method provided by the present invention can hydrogenate phenol in X oil to cyclohexanol and perform efficient separation, thereby achieving effective utilization of phenol in X oil and reducing material loss during the production process.

[0089] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing cyclohexanol from the by-product X oil in the hydration process of cyclohexanone production, characterized in that: The method includes: (1) In the presence of hydrogen, a mixed reaction oil containing X oil and an organic solvent is introduced into a fixed bed reactor filled with a hydrogenation catalyst for hydrogenation treatment to obtain a hydrogenation effluent; (2) introducing the hydroprocessing effluent into a desolventizing tower for first separation to obtain hydrogenated X oil and an organic solvent that can be recycled to step (1); (3) introducing the hydrogenated X oil into a cyclohexanol recovery tower for a second separation to obtain a cyclohexanol-containing gaseous effluent and heavy X oil; The X oil contains 40-50 wt% phenol, 5-16 wt% cyclohexanol, and 5-10 wt% cyclohexanone; the viscosity of the X oil is 6-10 mm 2 / s; In the mixed reaction oil, the volume ratio of the organic solvent to the X oil is 1-5:1; The hydrogenation catalyst comprises a carrier and an active metal component; the active metal component is nickel; and based on the total mass of the hydrogenation catalyst, the content of the active metal component in terms of element is 20-30 wt%.

2. The method according to claim 1, characterized in that In step (1), the conditions of the hydrotreatment include: temperature of 130-150°C, pressure of 1.4-2.5 MPa, volume space velocity of 2.5-4.6 h -1 .

3. The method according to claim 1 or 2, characterized in that In step (1), in the mixed reaction oil, the volume ratio of the organic solvent to the X oil is 2-3:1; and / or The organic solvent is C 6-7 Saturated alkanes and / or C 6-7 of saturated cycloalkanes.

4. The method according to any one of claims 1 to 3, characterized in that In step (1), the volume ratio of the hydrogen to the X oil is 400-500:

1.

5. The method according to any one of claims 1 to 4, characterized in that In the hydrogenation catalyst, the carrier is selected from at least one of alumina and silica.

6. The method according to any one of claims 1 to 5, characterized in that Based on the total mass of the hydrogenation catalyst, the content of the carrier is 70-80 wt % in terms of oxide.

7. The method according to any one of claims 1 to 6, characterized in that In step (2), the hydroprocessing effluent in the desolventizing tower is heated with steam; and / or In step (2), the operating pressure of the desolventizing tower is 5-15 KPaG, the top temperature is 82-90°C, the bottom temperature is 150-160°C, the reflux ratio is 0.4-1:1, and the number of theoretical plates is 20-30.

8. The method according to claim 7, characterized in that The hydroprocessing effluent is fed from the Nth theoretical plate of the desolventizing tower, where N is 10-12.

9. The method according to any one of claims 1 to 8, characterized in that In step (3), steam is used to heat the hydrogenated X oil in the cyclohexanol recovery tower; and / or In step (3), the operating pressure of the cyclohexanol recovery tower is 5-20 KPaA, the top temperature is 90-115° C., the bottom temperature is 120-135° C., and the number of theoretical plates is 20-30.

10. The method according to any one of claims 1 to 9, characterized in that The method further comprises: before introducing the mixed reaction oil into the fixed bed reactor, preheating the mixed reaction oil to 120-140° C. by steam in a feed heater, and then introducing the preheated mixed reaction oil into the fixed bed reactor for the hydrogenation treatment; Preferably, the preheating temperature is 5-10°C lower than the hydrotreatment temperature.

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