Preparation method of copper-based catalyst and application of copper-based catalyst in hydrogenation reaction

Abstract

The invention provides a preparation method of a copper-based catalyst, which is specifically applied to a reaction for preparing cyclohexane through benzene hydrogenation. The copper-based catalyst disclosed by the invention has relatively high dispersity, so that benzene can be hydrogenated to generate cyclohexane at a relatively low temperature. In addition, under the assistance of the auxiliary agent, the catalyst provided by the invention has more excellent catalytic performance, and almost all benzene can be converted into cyclohexane. The acid-base property of the surface of the catalyst can be regulated and controlled due to the introduction of the auxiliary agent, and the auxiliary agent can generate electron interaction with metal, so that the electronic performance of the surface of metal copper is regulated and controlled, and benzene can be converted into cyclohexane at a relatively low temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical industry, and particularly relates to an application in a reaction of benzene hydrogenation to cyclohexane. BACKGROUND

[0002] Cyclohexane is a common chemical raw material, which is often used as an intermediate for the production of adipic acid, cyclohexanol, cyclohexanone and caprolactam. The preparation methods of cyclohexane mainly include petroleum fractionation and benzene hydrogenation, and the benzene hydrogenation is the main method. In the benzene hydrogenation reaction, the production device mainly includes a fixed bed of gas-solid phase and a suspension bed of gas-liquid-solid three-phase, and the commonly used catalyst in the fixed bed reactor is a nickel-based and noble metal catalyst. The nickel-based catalyst, although cheap, has poor sulfur resistance and heat stability, and short service life; the noble metal catalyst has good sulfur resistance and is easy to regenerate after poisoning, but is expensive. For the above two catalysts, there are more researches at present. For example, patent CN115007141B uses 3-aminopropyltriethylsilane to treat ball clay, grafts -NH2 functional groups on the surface of the clay, and then deposits noble metals Ru and Pd. Patent CN102755909A dissolves Ru salt and AlCl3 in a solvent, and then dissolves alkyl imidazole hydrochloride in the solvent, thereby preparing a Ru-based catalyst. Patent CN102921410A loads noble metal Ru on alumina, silica and alumina-silica composite carriers, and then loads metal Ru on the carriers by the impregnation method. Patent CN112552138A immerses aluminum in a nitric acid solution of nickel, copper and tin, dries to remove water, and then calcines at 400 DEG C, thereby preparing a nickel-based catalyst.

[0003] Copper-based catalysts have good hydrogenation ability and are widely used in many hydrogenation reactions. For example, Wang et al. [Fuel 2025; 402: 135973] loaded Cu on CeO2, and used it to prepare methanol from CO2 hydrogenation under the promotion of Fe. Wang et al. [ACS Catalysis 2024; 14: 1620-1628] prepared Cu-CeZrO x The catalyst is used for dimethyl oxalate hydrogenation, and the selectivity of ethylene glycol is controlled by adjusting the Cu + / Cu 0 ratio on the surface of the catalyst. Tamura et al. [ACS Catalysis 2016; 1: 376-380] used Cu-CeO2 catalyst for dimethyl carbonate hydrogenation to prepare methanol. In view of the good hydrogenation performance of copper-based catalysts, they are applied to the benzene hydrogenation to cyclohexane, so as to avoid the problems such as high cost of noble metal catalysts. SUMMARY

[0004] The application provides a preparation method of a copper-based catalyst, which is mainly used for preparing cyclohexane by hydrogenation of benzene to overcome the problem of high cost of a noble metal catalyst, and a fixed bed reactor is used.

[0005] In the application, the preparation steps of the copper-based catalyst include: (1) uniformly mixing Cu salt, an additive M and a silicon source, and then loading the mixture into a high-pressure reaction kettle, and in-situ reduction under high-temperature and high-pressure hydrogen for 10-12 hours; (2) filtering and drying the sample in step (1), and then high-temperature calcining, and the obtained product is the copper-based catalyst.

[0006] In some preferred embodiments, the Cu salt in step (1) is one or more of Cu(NO3)2·3H2O, Cu(acac)2, CuCl2 and CuSO4.

[0007] In some preferred embodiments, the additive M in step (1) is one or more of alkali metals, boron group metals, rare earth metals, transition metals and black phosphorus powder.

[0008] The alkali metal includes any one of chlorides, fluorides, sulfates and carbonates of lithium, sodium and potassium.

[0009] The boron group metal includes boric acid and aluminum chloride.

[0010] The rare earth metal includes any one of chlorides of yttrium, scandium, lanthanum, cerium and neodymium.

[0011] The transition metal includes any one of chlorides of iron, cobalt, nickel, manganese and vanadium.

[0012] The silicon source in step (1) is one or more of silica sol-gel, white carbon black and commercial silicon dioxide.

[0013] The content of Cu in step (1) is 10 wt%-20 wt%, the content of the additive M is 0.5 wt%-3.0 wt%, and the content of the silicon source is 3.0 wt%-5.0 wt%.

[0014] The high-temperature and high-pressure condition is 180-200 DEG C, and the pressure is 5-10 MPa.

[0015] The temperature of high-temperature calcining in step (2) is 300 DEG C-600 DEG C, and the calcining time is 2 h-6 h.

[0016] The application further provides a copper-based catalyst prepared by the method, and the copper-based catalyst is applied to a hydrogenation catalytic reaction.

[0017] Compared with the prior art, the application has the following advantages: The present application provides a preparation method of a copper-based catalyst, which is particularly applied to the reaction of benzene hydrogenation to cyclohexane. Compared with traditional noble metal catalysts, the catalysts involved in the present application have the advantages of low cost and good catalytic performance. This is mainly due to the high dispersion of the copper-based catalysts in the present application, thereby improving the hydrogenation performance. In addition, the introduction of the auxiliary agent can also promote the adsorption of the reactant benzene to some extent, thereby further improving the conversion rate of benzene and reducing the reaction temperature. In addition, the in-situ reduction method used in the present application can control the particle size of the metal, thereby exposing more catalytically active sites, so that the benzene hydrogenation reaction can be carried out at a lower reaction temperature. DETAILED DESCRIPTION

[0018] The present application provides a preparation method of a copper-based catalyst, which is particularly applied to the reaction of benzene hydrogenation to cyclohexane.

[0019] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application will be described in detail below with examples. It should be pointed out that the specific examples described here are only used to explain the present application, and are not limited to the embodiments of the present application. Any changes, modifications, combinations, simplifications and substitutions made without departing from the spirit and principles of the present application shall be equivalent replacement methods and shall be included in the protection scope of the present application.

[0020] In the present application, unless otherwise specified, the evaluation method of benzene hydrogenation to cyclohexane is as follows: a certain amount of catalyst and water are loaded into a fixed bed reaction tube, hydrogen is filled and then evacuated, and this is repeated three times to remove air in the device. After pressure build-up and leak detection, 50 ml / min of hydrogen is introduced at 350℃, and the prepared catalyst is reduced for 5 h. After the reduction is completed, the reaction begins.

[0021] In the present application, unless otherwise specified, the catalytic activity test of benzene hydrogenation to cyclohexane is carried out by using a fixed bed reactor, and the reaction conditions are as follows: 1.0 MPa, 90℃, WLHSV 苯 =1.0 h -1 , and the molar ratio of H2 to benzene is 30:1.

[0022] In the present application, unless otherwise specified, the conversion rate of benzene and the selectivity of cyclohexane listed in Table 1 are the average values after stable operation for 100 h.

[0023] In order to further illustrate the present application, the following examples are described in detail, but the protection scope of the present application is not limited to the following examples.

[0024] Example 1 Into 250 ml deionized water, 5.1568 g Cu(NO3)2·3H2O and 0.6336 g La(NO3)3·6H2O were added, after stirring and dissolving, 30 g of 40 wt% silica sol-gel was added, mechanically stirred until completely mixed, then loaded into a high-pressure reaction kettle, reduced at 200℃, 5 MPa hydrogen for 12 h, then filtered and calcined at 350℃ for 5 h, and the final copper-based catalyst was obtained.

[0025] In this embodiment, the loading of Cu was 10 wt%, and the loading of La was 1.5 wt%.

[0026] Example 2 The copper-based catalyst was prepared according to Example 1, except that in this embodiment, the loading of La was 3.0 wt%.

[0027] Example 3 The copper-based catalyst was prepared according to Example 1, except that in this embodiment, the loading of Cu was 15 wt%.

[0028] Example 4 The copper-based catalyst was prepared according to Example 1, except that in this embodiment, the salt of the auxiliary agent M was Co(NO3)2·6H2O, and the loading of Co was 1.5 wt%.

[0029] Example 5 The copper-based catalyst was prepared according to Example 1, except that in this embodiment, the calcination temperature was 500℃, and the calcination time was 5 h.

[0030] Example 6 Into 250 ml deionized water, 5.1568 g Cu(NO3)2·3H2O and 0.6336 g La(NO3)3·6H2O were added, after stirring and dissolving, 30 g of 40 wt% silica sol-gel was added, mechanically stirred until completely mixed, then loaded into a high-pressure reaction kettle, reduced at 200℃, 5 MPa hydrogen for 12 h, then filtered and calcined at 350℃ for 5 h, and the final copper-based catalyst was obtained.

[0031] In this embodiment, the loading of Cu was 10 wt%, and the loading of La was 1.5 wt%.

[0032] Example 7 The copper-based catalyst was prepared according to Example 6, except that in this embodiment, the loading of La was 3.0 wt%. A copper-based catalyst was prepared according to Example 6, except that in this example the promoter M was a dispersion of black phosphorus and the loading of black phosphorus was 1.5 wt%.

[0033] Example 9 Into 250 ml of deionized water, 5.1568 g of Cu(N03)2-3H20 and 0.6336 g of La(N03)3-6H20 were added, after being stirred and dissolved, 30 g of 40 wt% silica sol-gel was added, mechanically stirred until completely mixed, 20 g of 40 wt% NaOH solution was added at one time, after continuous stirring for 0.5 h, it was loaded into a high-pressure reaction kettle, reduced at 200 °C, 5 MPa hydrogen for 12 h, then filtered and calcined at 350 °C for 5 h, and finally the copper-based catalyst was obtained. In this example, the loading of Cu was 10 wt% and the loading of La was 1.5 wt%.

[0034] Example 10 A copper-based catalyst was prepared according to Example 3, except that in this example the salt of the promoter M was Y(N03)3and the loading of Y was 1.5 wt%.

[0035] Comparative Example 1 A catalyst was prepared according to Example 1, except that in this example the loading of Cu was 0 wt%.

[0036] Comparative Example 2 A catalyst was prepared according to Example 6, except that in this example the loading of Cu was 0 wt%.

[0037] Comparative Example 3 A catalyst was prepared according to Example 1, except that in this example the loading of La was 0 wt%.

[0038] Comparative Example 4 A catalyst was prepared according to Example 9, except that in this example the loading of La was 0 wt%.

[0039] Table 1. Performance results of benzene hydrogenation of Examples.

[0040]

[0041] The above samples were subjected to benzene hydrogenation activity evaluation, and the evaluation conditions were as described above. The catalytic activity test results are listed in Table 1. From the implementation results, the copper-based catalyst has higher dispersion, thereby exposing more copper active sites, so that it can generate cyclohexane from benzene hydrogenation at a lower temperature. In addition, with the assistance of the adjuvant, the copper-based catalyst has more excellent hydrogenation capacity and can generate more cyclohexane at a lower temperature. This is mainly due to the introduction of the adjuvant, which changes the surface acid-base properties of the catalyst, the electronic properties of the copper surface, and promotes metal dispersion.

Claims

1. A method for preparing a copper-based catalyst, characterized in that, Includes the following steps: (1) After mixing Cu salt, additive M and silicon source evenly, put them into a high-pressure reactor and carry out in-situ reduction reaction under high temperature and high pressure hydrogen conditions for 10-12 hours. (2) After filtering and drying the sample in step (1), it is calcined at high temperature to obtain the copper-based catalyst.

2. The method according to claim 1, characterized in that, In step (1), the Cu salt is one or more of Cu(NO3)2•3H2O, Cu(acac)2, CuCl2, and CuSO4.

3. The method according to claim 1, characterized in that, In step (1), the auxiliary agent M is one or more of the following: alkali metals, boron group metals, rare earth metals, transition metals, and black phosphorus powder.

4. The method according to claim 1, characterized in that, In step (1), the silicon source is one or more of silica sol-gel, silica, and commercial silica.

5. The method according to claim 1, characterized in that, In step (1), the Cu content is 10 wt%-20 wt%, the additive M content is 0.5 wt%-3.0 wt%, and the silicon source content is 3.0 wt%-5.0 wt%.

6. The method according to claim 1, characterized in that, The high temperature and high pressure conditions are 180-200℃ and 5-10 MPa.

7. The method according to claim 1, characterized in that, In step (2), the high-temperature roasting temperature is 300℃-600℃ and the roasting time is 2 h-6 h.

8. A copper-based catalyst, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The application of the copper-based catalyst according to claim 8 in hydrogenation catalytic reactions.

10. The application according to claim 9, wherein the hydrogenation catalytic reaction refers to its application in the hydrogenation of benzene to cyclohexane.

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