Preparation method and application of Mo2C supported catalyst

Abstract

The present invention provides a preparation method and application of a Mo2C supported catalyst. A quantitative noble metal Ru salt, a molybdenum salt, and an organic carbon source are added to a solvent, stirred and dissolved, stirred for reaction, and vacuum dried overnight to obtain a catalyst sample precursor. The catalyst sample precursor is introduced into pure H2 for reduction. After the reduction is complete, a 1% O2-Ar mixed gas is introduced for passivation to obtain a supported Ru-based catalyst. Compared with traditional industrial catalysts, the Ru-based catalysts of the present invention have a lower noble metal content, have a good cost advantage, and provide certain possibilities for subsequent industrial applications.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a Mo2C supported catalyst and application of the catalyst in a reaction of partially hydrogenating benzene to produce cyclohexene. Background Art

[0002] Cyclohexene is an important organic chemical raw material, often used as an intermediate in petrochemicals, pharmaceuticals, pesticides, and dyes, and has extensive applications in the petroleum and fine chemical industries. In caprolactam production, cyclohexene hydration produces cyclohexanol, which is then oxidized and dehydrated to produce cyclohexanone. Cyclohexanone undergoes ammoximation to produce cyclohexanone oxime, which then undergoes molecular rearrangement to produce caprolactam. Currently, cyclohexene production methods include partial hydrogenation of benzene, cyclohexanol dehydration, cyclohexane dehydrogenation, and Birch reduction. Due to its simplicity and low production cost, partial hydrogenation of benzene is commonly used in industrial cyclohexene production.

[0003] The difficulty in partially hydrogenating benzene to cyclohexene lies in the active C=C double bond in the product cyclohexene, which readily undergoes deep hydrogenation to produce cyclohexane, and is thermodynamically more prone to cyclohexane formation. Therefore, to achieve efficient cyclohexene production, it is necessary to select a suitable reaction system to avoid excessive hydrogenation of the product to produce cyclohexane. This issue has been systematically studied in numerous publications and patents. For example, patent CN1984712A discloses a catalyst for the partial hydrogenation of benzene to cyclohexene. This patent stipulates that the proportion of catalyst pores within the 2-15 nm range should be greater than 50%, otherwise cyclohexene production will be detrimental. Patent CN106140154B proposes a contrasting conclusion, arguing that the proportion of catalyst pores within the 2-15 nm range should be less than 50% to facilitate cyclohexene production and improve catalyst stability. Patent CN102264471A proposes that reducing a Ru-based catalyst in an aqueous solution containing a metal salt can improve cyclohexene yield to a certain extent. Patent CN108409520B proposes alkali treatment of a RuZn catalyst to improve catalyst stability and cyclohexene yield. Catalytic activity tests showed that after 200 hours of continuous operation, the catalyst still achieved a cyclohexene yield of 41.2% (i.e., a benzene conversion of 48.5% and a cyclohexene selectivity of 84.9%). Summary of the Invention

[0004] In order to solve the above problems, the present invention aims to provide a method for preparing a Mo2C supported catalyst and its application in the partial hydrogenation of benzene to cyclohexene.

[0005] The technical solutions of the present invention are as follows:

[0006] (1) Ru salt, molybdenum salt and organic carbon source are added to a solvent, stirred to dissolve, stirred to react, and vacuum dried overnight to obtain a catalyst sample precursor;

[0007] (2) The catalyst sample precursor was reduced by introducing pure H2. After the reduction was completed, 1% O2-Ar mixed gas was introduced for passivation to obtain the supported Ru-based catalyst Ru-Mo2C.

[0008] In some preferred embodiments, the metal Ru salt in step (1) is one or more of RuCl3, Ru(acac)3, tris(triphenylphosphine)ruthenium chloride, and Ru(NO)(NO3)3.

[0009] In some preferred embodiments, the molybdenum salt in step (1) is one or more of sodium molybdate, ammonium molybdate, ammonium phosphomolybdate, molybdenum acetylacetonate, molybdenum chloride or molybdenum hexacarbonyl.

[0010] In some preferred embodiments, the organic carbon source in step (1) is one or more of sugars, organic amines, and amides.

[0011] In some preferred embodiments, the mass ratio of the molybdenum salt to the organic carbon source in step (1) is (1-100): (1-100).

[0012] In some preferred embodiments, the solvent in step (1) is one or more of ammonia water, deionized water and ethanol.

[0013] In some preferred embodiments, the stirring reaction conditions in step (1) are 70-90 °C for 10-15 h, and then vacuum drying at 100 °C overnight; preferably, stirring at 80 °C for 12 h, and then vacuum drying at 100 °C overnight.

[0014] In some preferred embodiments, the reduction temperature in step (2) is 200°C to 1000°C.

[0015] In some preferred embodiments, the Ru loading in step (2) is 1.0 wt% to 5.0 wt%.

[0016] The present invention provides a method for preparing the Mo2C supported catalyst described in the above technical solution, and its application in the reaction of partially hydrogenating benzene to produce cyclohexene.

[0017] The advantages of the present invention are:

[0018] The present invention provides a method for preparing a Mo2C-supported catalyst and its application in the partial hydrogenation of benzene to cyclohexene. Due to the strong interaction between Mo2C and the metal Ru, the precious metal Ru can be better dispersed, exposing more Ru active sites on the catalyst surface. This allows for a higher cyclohexene yield at a lower loading and significantly reduces the amount of zinc sulfate used in the reaction from the traditional 10g to 2g. Furthermore, Mo2C has precious metal-like properties and possesses certain performance in the partial hydrogenation of benzene to cyclohexene. The synergistic effect of the precious metal Ru enables the Ru-Mo2C catalyst to achieve a higher cyclohexene yield.

[0019] It is difficult to prepare a catalyst with a low Ru loading. The present invention achieves a lower loading of 1.5%-5% by synchronous feeding and combining the screening of carbon sources and solvent types.

[0020] Compared with existing industrial catalysts (metal Ru content of about 10 wt%), the catalyst provided by the present invention has the advantages of low metal Ru content, low cost burden and high cyclohexene yield, and has a price advantage in large-scale industrial applications. DETAILED DESCRIPTION

[0021] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] In the context of this specification, except for the contents explicitly described, any matters or issues not mentioned are directly based on the technology known in the art. Moreover, any embodiment described in this patent can be freely combined with one or more other embodiments described in this patent, and the technical solutions or technical ideas formed thereby are considered as part of the original disclosure or original description of the present invention, and should not be regarded as new content not disclosed in this patent, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0023] The data points disclosed in this patent include not only the specific numerical points disclosed, but also the endpoints of the numerical ranges. Any combination of these data points should be considered as the disclosed or described range of the present invention, regardless of whether these numerical points are disclosed one by one in this document.

[0024] In the present invention, the catalytic performance evaluation device used is a kettle reactor. Unless otherwise specified, the evaluation method for the partial hydrogenation of benzene to cyclohexene is as follows: a certain amount of catalyst is weighed and added to the reactor. After multiple pressure charging and pressure relief, the air in the reactor is completely discharged, and the pressure is maintained to check for leaks. After the reaction is normal, the temperature is raised and the reaction is started. After the temperature reaches the target temperature, benzene is added and the reaction timer is started.

[0025] In the present invention, unless otherwise specified, the reaction conditions are 5.0 MPa, 155°C, a rotation speed of 1000 r / min, 1 g of catalyst, 50 mL of benzene, 100 mL of water, and 2 g of ZnSO4.

[0026] In the present invention, unless otherwise specified, the benzene conversion and cyclohexene selectivity listed in Table 1 are all obtained under the conditions of maximum cyclohexene yield.

[0027] To further illustrate the present invention, the following embodiments are described in detail, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] Weigh 8.65 g (NH4)6Mo7O 24 •4H2O (abbreviated as AHM), 0.21 g RuCl3, and 7.84 g hexamethylenetetramine (abbreviated as HMT) were dissolved in 150 ml of deionized water, stirred at 80 °C for 12 h, and then vacuum-dried at 100 °C overnight. The resulting sample was the catalyst sample precursor. The noble metal Ru loading was 2 wt%, and the molar ratio of AHM to HMT was 1:8.

[0030] The sample was reduced at 700°C for 2 h under a hydrogen flow rate. Ar gas was introduced to cool the sample. After cooling to room temperature, 1% O₂-N₂ was introduced for passivation for 12 h. The resulting catalyst was Ru-Mo₂C.

[0031] Example 2

[0032] The Ru-Mo2C catalyst was prepared with reference to Example 1. The difference from Example 1 was that the loading amount of the precious metal Ru in this example was 5 wt%.

[0033] Example 3

[0034] The Ru-Mo2C catalyst was prepared with reference to Example 1. Unlike Example 1, the molar ratio of AHM to HMT in this example was 1:4.

[0035] Example 4

[0036] The Ru-Mo2C catalyst was prepared with reference to Example 1. The difference from Example 1 is that the solvent in this example is ethylene glycol.

[0037] Example 5

[0038] The Ru-Mo2C catalyst was prepared with reference to Example 1. Unlike Example 1, the organic carbon source in this example was sucrose, and the molar ratio of AHM to sucrose was 1:10.

[0039] Example 6

[0040] The Ru-Mo2C catalyst was prepared with reference to Example 5. Unlike Example 5, the molar ratio of AHM to sucrose in this example was 1:5.

[0041] Example 7

[0042] The Ru-Mo2C catalyst was prepared with reference to Example 5. The difference from Example 5 was that the loading amount of the precious metal Ru in this example was 5 wt%.

[0043] Example 8

[0044] The Ru-Mo2C catalyst was prepared with reference to Example 1. The difference from Example 1 was that the molybdenum source in this example was molybdenum acetylacetonate.

[0045] Example 9

[0046] The Ru-Mo2C catalyst was prepared with reference to Example 1. Unlike Example 1, the reduction temperature in this example was 500 °C.

[0047] Comparative Example 1

[0048] Weigh 10 g of ZrOCl2•8H2O and add it to 100 ml of water. After mechanical stirring until completely dissolved, add ammonia to adjust the solution's pH to 10. Then, reflux at 80°C for 12 hours to completely hydrolyze the ZrOCl2•8H2O. After hydrolysis, separate the product by centrifugation. To ensure complete removal of Cl ions, the product undergoes multiple cycles of stirring, dispersion, and centrifugation until the upper layer of separated liquid drops into the AgNO3 solution without precipitation. Finally, dry the washed precipitate at 130°C overnight and calcine at 800°C for 5 hours before labeling it as ZrO2.

[0049] Weigh 2 g ZrO2, add it into 40 ml water, stir it with a magnetic stirrer until it is evenly dispersed, then add 0.21 g RuCl3, stir it at 80 °C, and then add 2 mol / L KBH4 solution dropwise. 3+ The molar ratio of Ru to ZrO2 was 4:1, the metal was reduced, and finally, after multiple centrifugal washings, the precipitate was dried at 130 ° C overnight to obtain the catalyst Ru / ZrO2. In this example, the Ru loading was 5.0 wt%.

[0050] Comparative Example 2

[0051] The Ru-Mo2C catalyst was prepared with reference to Example 1. The difference from Example 1 is that the precious metal Ru was not present in this example.

[0052] The above samples were subjected to benzene partial hydrogenation activity evaluation. The evaluation conditions were as described above. The catalytic activity test results are listed in Table 1.

[0053] The results show that the activity of Mo2C alone in the partial hydrogenation of benzene to cyclohexene is weak, but its catalytic performance is significantly enhanced after loading with metallic Ru. The cyclohexene yield of the optimal Ru-Mo2C catalyst is much higher than that of Comparative Sample 1. This is primarily due to the strong interaction between Ru and Mo2C, which facilitates the dispersion of metallic Ru, thereby forming a large number of Ru active sites on the catalyst surface. In addition, Mo2C has precious metal-like properties and can act as a catalyst promoter to promote the formation of cyclohexene. Compared with the conventional Ru / ZrO2, Ru-Mo2C has a higher cyclohexene yield.

[0054] Table 1 Example benzene partial hydrogenation performance results

[0055]

[0056] The above embodiments are used to explain the technical solutions of the present invention. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by those skilled in the art based on the present invention, or equivalent substitutions of materials used in the present invention, etc., fall within the scope of protection of the patent.

Claims

1. An application of a Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene, characterized in that: The preparation method of the catalyst comprises the following steps: (1) Ru salt, molybdenum salt and organic carbon source are added to a solvent, stirred to dissolve, stirred to react, and vacuum dried overnight to obtain a catalyst sample precursor; (2) The catalyst sample precursor was reduced by introducing pure H2. After the reduction was completed, 1% O2-Ar mixed gas was introduced for passivation to obtain the supported Ru-based catalyst Ru-Mo2C.

2. The application of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The metal Ru salt in step (1) is one or more of RuCl3, Ru(acac)3, tris(triphenylphosphine)ruthenium chloride, and Ru(NO)(NO3)3; The molybdenum salt is one or more of sodium molybdate, ammonium ... phosphomolybdate, molybdenum acetylacetonate, molybdenum chloride or molybdenum hexacarbonyl.

3. The application of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The organic carbon source in step (1) is one or more of sugars, organic amines, and amides.

4. The application of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The mass ratio of the molybdenum salt to the organic carbon source in step (1) is (1-100): (1-100).

5. The application of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The solvent in step (1) is one or more of ethylene glycol, deionized water, and ethanol.

6. The use of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The stirring reaction conditions in step (1) are 70-90°C for 10-15 hours, and then vacuum drying at 100°C overnight.

7. The use of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 6, characterized in that: The stirring reaction conditions in step (1) are 80°C for 12 hours, and then vacuum drying at 100°C overnight.

8. The use of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The reduction temperature in step (2) is 200°C to 1000°C.

9. The use of the Mo2C supported catalyst in the partial hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The Ru loading amount in step (2) is 1.0 wt% to 5.0 wt%.

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