Preparation method of catalyst for selective hydrogenation of benzene to cyclohexene

Abstract

The invention belongs to the technical field of selective hydrogenation of benzene to produce cyclohexene, and is specifically related to a preparation method of a catalyst for selective hydrogenation of benzene to produce cyclohexene, comprising the following steps: S1, synthon A and synthon B and a reaction solvent are put into a reactor, and a framework material C is obtained by reaction; S2, framework material C is put into a container and added to an organic solvent to form a suspension, and then a noble metal salt solution is added to the suspension to obtain a loaded framework material G; S3, using loaded framework material G as a mother liquor, a dilute solution is added to the mother liquor to form a loaded liquid, and the loaded liquid is impregnated into an organic porous material surface, and the organic porous material impregnated with the loaded liquid is aged, dried, roasted, and activated to obtain a catalyst for selective hydrogenation of benzene to produce cyclohexene. The catalyst obtained by the preparation method in the present invention is applied to the reaction of selective hydrogenation of benzene to produce cyclohexene, and the conversion of benzene is as high as 47 50%, and the selectivity of cyclohexene is as high as 78 82%.

Description

Technical Field

[0001] The invention belongs to the technical field of cyclohexene production by selective hydrogenation of benzene, and particularly relates to a method for preparing a catalyst for cyclohexene production by selective hydrogenation of benzene. Background Art

[0002] Cyclohexene is a very important organic synthesis intermediate, widely used in the production of polyester materials, pharmaceuticals, feed additives, agricultural chemicals, and other fine chemical products, and can be used as a solvent. Advances in cyclohexene production processes are closely linked to the greening of the caprolactam industry. Cyclohexene is produced by selective hydrogenation of benzene, which is then hydrated to produce cyclohexanol. This process consumes approximately one-third less hydrogen than traditional processes, produces only cyclohexane as a byproduct, and achieves a 100% carbon yield. It offers significant advantages such as safety, reliability, a short process, energy efficiency, zero waste generation, ease of operation, low cost, and environmental friendliness. From an atom-economy perspective, the caprolactam process starting with cyclohexene offers superior economic performance.

[0003] In the research process of catalytic system for partial hydrogenation of benzene to cyclohexene, the materials of active components of the catalyst mostly revolve around Group VIII and its subgroup metals, such as Ni, Pt, Pd, Rh and Ru.

[0004] Currently, ruthenium-based benzene partial hydrogenation catalysts are prepared using various methods, including impregnation, precipitation, sol-gel, and microemulsion. These catalysts, when used in the selective hydrogenation of benzene to cyclohexene, typically achieve benzene conversion rates of around 40% and cyclohexene selectivity of around 70%. However, these catalysts suffer from high costs, low utilization of the active precious metal component, a limited number of support types, and low selectivity. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene. The catalyst prepared by the preparation method of the present invention is used in the reaction of selective hydrogenation of benzene to cyclohexene, and the conversion rate of benzene is as high as 46-50%, and the selectivity of cyclohexene is as high as 78-82%.

[0006] The specific technical solution adopted in the present invention is:

[0007] A method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene comprises the following steps:

[0008] S1. Place synthon A, synthon B, and a reaction solvent into a reaction kettle, heat to 90-200° C., and react for 12-100 hours to generate framework material C;

[0009] S2. Put the framework material C into a container and add it to an organic solvent, stir to form a suspension, then add the noble metal salt solution to the suspension, and then heat it to 50-100° C. and react for 4-8 hours to generate the supported framework material G;

[0010] S3, using the supported framework material G as a mother liquid, adding a dilute solution to the mother liquid to form a loading liquid, immersing the organic porous material in the loading liquid, then removing the organic porous material and drying the loading liquid on its surface, aging, drying, calcining, and activating the organic porous material impregnated with the loading liquid to obtain a catalyst for selective hydrogenation of benzene to cyclohexene;

[0011] Wherein, the synthon A includes 2,5-dihydroxyterephthalaldehyde or a heterocyclic macromolecular compound having a BO structure;

[0012] The synthon B includes tris(4-amino)aniline trihydrochloride or a conjugated macrocyclic compound with a BN structure.

[0013] The molar ratio of the synthon A to the synthon B is 1:1 to 1:2.

[0014] The reaction solvent includes any one of 1,4-dioxane, mesitylene and acetic acid, and the ratio of the sum of the mass of the synthon A and the synthon B to the mass of the reaction solvent is 1:40-60.

[0015] The organic solvent includes any one of methanol, ethanol, benzene, toluene, cyclohexane, and methylcyclohexane.

[0016] The molar ratio of the framework material C to the organic solvent is 1.1 to 1.5.

[0017] The precursor of the noble metal salt solution exists in the form of nitrate, acetate, or chloride, and the solvent of the noble metal salt solution is any one of 1,4-dioxane, mesitylene, and acetic acid.

[0018] The molar ratio of the noble metal ions in the noble metal salt solution to the framework material C in the suspension is 2:1 to 1:2.

[0019] The dilute solution includes any one of methanol and ethanol.

[0020] The metal ion concentration in the loading liquid is 0.5-1.2 mol / L.

[0021] When the noble metal salt solution is a ruthenium metal salt solution, step S3 includes the following steps:

[0022] The loaded framework material G is used as the mother liquor, a dilute solution is added to the mother liquor to form a loaded liquid, the organic porous material is immersed in the loaded liquid, and then the organic porous material is taken out and immersed in a ZnSO4 additive. The organic porous material is then taken out and its surface is heated and dried. The organic porous material impregnated with the loaded liquid and the ZnSO4 additive is aged, dried, calcined, and activated to obtain a catalyst for selective hydrogenation of benzene to cyclohexene.

[0023] The beneficial effects of the present invention are:

[0024] 1. The catalyst prepared in the present invention has high selectivity for cyclohexene. This is because the utilization rate of the active precious metal component of the catalyst is high. The precious metal is in a single-atom dispersed state. Therefore, when the framework material C is prepared in the early stage, the site of the anchoring metal is reserved. The suspension containing the framework material C is reacted with the precious metal salt solution. The precious metal in a single-atom dispersed state will be embedded in the site of the anchoring metal, thereby improving the utilization rate of the precious metal component.

[0025] 2. The load-bearing framework material G in the present invention is a hexahedral cage-like structure, and can form a stable combination with most organic porous materials, such as carbon microspheres, activated carbon, alumina, molecular sieves, attapulgite, montmorillonite, silica, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the catalyst synthesis of the present invention;

[0027] Figure 2 Schematic diagram of the topological structure of frame material C. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: 1. Specific embodiments

[0030] Example 1

[0031] S1. Synthon A, synthon B and 1,4-dioxane are placed in a reaction vessel, heated to 150°C for 48 hours, and the framework material C is generated by a solvent thermal synthesis method.

[0032] Wherein, the synthon A is 2,5-dihydroxyterephthalaldehyde;

[0033] The synthon B is tris(4-amino)aniline trihydrochloride;

[0034] The molar ratio of synthon A to synthon B and 1,4-dioxane is 1:1.2, and the ratio of the sum of the mass of synthon A and synthon B to the mass of 1,4-dioxane is 1:50;

[0035] S2. Framework material C is placed in a container and added toluene, stirred to form a suspension, and then ruthenium acetate solution is added to the suspension, and then heated to 80° C. for 6 hours to react to generate supported framework material G;

[0036] The molar ratio of the framework material C to toluene is 1:1.3, and the molar ratio of the ruthenium acetate solution to the framework material C is 1:1.2.

[0037] S3, using the supported framework material G as a mother liquid, adding methanol to the mother liquid to form a supported liquid, impregnating the supported liquid into the surface of the carbon microspheres, placing the carbon microspheres impregnated with the supported liquid into a ZnSO4 additive and impregnating them again, then taking out the carbon microspheres and placing them in a tray, aging them at room temperature for 2 hours, then placing them in a muffle furnace under the protection of inert gas N2, calcining them at 450°C for 1 hour, and finally activating them with hydrogen at 100°C to obtain a catalyst for selective hydrogenation of benzene to cyclohexene;

[0038] The concentration of ruthenium ions in the loading solution is 0.8 mol / L, and the concentration of zinc ions in the ZnSO4 additive is 4%.

[0039] Example 2

[0040] S1. Synthon A, synthon B and mesitylene are placed in a reactor, heated to 100°C for 72 hours, and a solvent thermal synthesis method is used to generate framework material C.

[0041] Wherein, the synthon A is 2,5-dihydroxyterephthalaldehyde;

[0042] The synthon B is tris(4-amino)aniline trihydrochloride;

[0043] The molar ratio of synthon A to synthon B and 1,4-dioxane is 1:1, and the ratio of the sum of the mass of synthon A and synthon B to the mass of mesitylene is 1:40;

[0044] S2. Framework material C is placed in a container and added to cyclohexane, stirred to form a suspension, and then rhodium acetate solution is added to the suspension, and then heated to 50° C. for 8 hours to react to generate supported framework material G;

[0045] The molar ratio of the framework material C to toluene is 1:1.1, and the molar ratio of the rhodium acetate solution to the framework material C is 1:1.

[0046] S3, using the supported framework material G as a mother liquid, adding methanol to the mother liquid to form a loading liquid, impregnating the loading liquid into the surface of the carbon microspheres, placing the carbon microspheres impregnated with the loading liquid in a tray, aging at room temperature for 1 hour, then placing the carbon microspheres in a muffle furnace under the protection of inert gas Ar, calcining at 600° C. for 30 minutes, and finally activating the catalyst with hydrazine hydrate to obtain a catalyst for selective hydrogenation of benzene to cyclohexene;

[0047] The rhodium ion concentration in the loading solution is 0.5 mol / L.

[0048] Example 3

[0049] S1. Synthon A, synthon B and mesitylene are placed in a reactor, heated to 170° C. for 24 hours, and a solvent thermal synthesis method is used to generate framework material C.

[0050] Wherein, the synthon A is 2,5-dihydroxyterephthalaldehyde;

[0051] The synthon B is tris(4-amino)aniline trihydrochloride;

[0052] The molar ratio of synthon A to synthon B and 1,4-dioxane is 1:2, and the ratio of the sum of the mass of synthon A and synthon B to the mass of mesitylene is 1:60;

[0053] S2. Framework material C is placed in a container and added to methylcyclohexane, stirred to form a suspension, and then ruthenium acetate solution is added to the suspension, and then heated to 100° C. for 4 hours to react to generate supported framework material G;

[0054] The molar ratio of the framework material C to toluene is 1:1.5, and the molar ratio of the ruthenium acetate solution to the framework material C is 1:2.

[0055] S3, using the supported framework material G as a mother liquid, adding methanol to the mother liquid to form a supported liquid, impregnating the supported liquid into the surface of the carbon microspheres, placing the carbon microspheres impregnated with the supported liquid into a ZnSO4 additive and impregnating them again, then taking out the carbon microspheres and placing them in a tray, aging them at room temperature for 1.5 hours, then placing them in a muffle furnace under the protection of inert gas N2, and calcining them at 350°C for 2 hours, and finally activating them to obtain a catalyst for selective hydrogenation of benzene to cyclohexene;

[0056] The concentration of ruthenium ions in the loading solution is 1.2 mol / L, and the concentration of zinc ions in the ZnSO4 additive is 4%.

[0057] 2. Performance Testing

[0058] The catalysts prepared in the examples were used for the selective hydrogenation of benzene to produce cyclohexene using a liquid phase process at a reaction temperature of 150° C. and a pressure of 4.8 MPa. The reaction results are shown in Table 1.

[0059] Table 1

[0060]

[0061] It can be seen that the catalyst for selective hydrogenation of benzene to cyclohexene prepared by the preparation method of the present invention has a high precious metal loading, a single-pass conversion rate of benzene of 47-50%, and a cyclohexene selectivity of 78-82%, which far exceeds the effect of existing catalysts.

Claims

1. A method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene, characterized in that: The following steps are involved: S1. Place synthon A, synthon B, and a reaction solvent into a reaction kettle, heat to 90-200° C., and react for 12-100 hours to generate framework material C; S2. Framework material C is placed in a container and added to an organic solvent, stirred to form a suspension, and then a noble metal salt solution is added to the suspension, and then heated to 50-100° C. for 4-8 hours to react to generate a supported framework material G; S3, using the supported framework material G as a mother liquid, adding a dilute solution to the mother liquid to form a loading liquid, immersing the organic porous material in the loading liquid, then removing the organic porous material and drying the loading liquid on its surface, aging, drying, calcining, and activating the organic porous material impregnated with the loading liquid to obtain a catalyst for selective hydrogenation of benzene to cyclohexene; Wherein, the synthon A is 2,5-dihydroxyterephthalaldehyde; The synthon B is tris(4-amino)aniline trihydrochloride.

2. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The molar ratio of the synthon A to the synthon B is 1:1 to 1:

2.

3. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The reaction solvent includes any one of 1,4-dioxane, mesitylene and acetic acid, and the ratio of the sum of the mass of the synthon A and the synthon B to the mass of the reaction solvent is 1:40-60.

4. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The organic solvent includes any one of methanol, ethanol, benzene, toluene, cyclohexane, and methylcyclohexane.

5. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The molar ratio of the framework material C to the organic solvent is 1.1 to 1.

5.

6. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The precursor of the noble metal salt solution exists in the form of nitrate, acetate, or chloride, and the solvent of the noble metal salt solution is any one of 1,4-dioxane, mesitylene, and acetic acid.

7. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The molar ratio of the noble metal ions in the noble metal salt solution to the framework material C in the suspension is 2:1 to 1:

2.

8. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The dilute solution includes any one of methanol and ethanol.

9. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, wherein: The metal ion concentration in the loading liquid is 0.5-1.2 mol / L.

10. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: When the noble metal salt solution is a ruthenium metal salt solution, step S3 includes the following steps: The loaded framework material G is used as the mother liquor, a dilute solution is added to the mother liquor to form a loaded liquid, the organic porous material is immersed in the loaded liquid, and then the organic porous material is taken out and immersed in a ZnSO4 additive. The organic porous material is then taken out and its surface is heated and dried. The organic porous material impregnated with the loaded liquid and the ZnSO4 additive is aged, dried, calcined, and activated to obtain a catalyst for selective hydrogenation of benzene to cyclohexene.

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