A catalyst and its preparation method and application

Abstract

The present invention provides a catalyst and a preparation method and application thereof, wherein the catalyst comprises 2-5% nickel element by mass percentage, and the remainder is copper-modified Beta molecular sieve. The catalyst provided by the present invention uses nickel as an active metal, and the presence of copper element in the copper-modified Beta molecular sieve can improve the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene when catalyzing the selective hydrogenation of biphenyl.

Description

Technical Field

[0001] The invention belongs to the field of material technology, and in particular relates to a catalyst and a preparation method and application thereof. Background Art

[0002] Cyclohexylbenzene (CHB), also known as phenylcyclohexane, has a molecular formula of C 12 H 16 It is composed of a three-dimensional cyclohexyl group and a planar benzene ring, and its boiling point is 239-240°C. Cyclohexylbenzene is widely used in industry due to its special physical and chemical properties. For example, cyclohexylbenzene can be used as an anti-overcharge protector for lithium-ion battery electrolytes to improve the safety and recycling rate of lithium-ion batteries. In addition, cyclohexylbenzene molecules contain two six-membered rings, which are excellent raw materials for making TFT liquid crystal materials. In recent years, the demand for cyclohexylbenzene has increased year by year, and its price has remained high.

[0003] At present, the main routes for synthesizing cyclohexylbenzene include the alkylation of benzene and cyclohexene, the selective hydrogenation of biphenyl, and the one-step method of benzene plus alkylating agent. As a byproduct of the coal chemical process, biphenyl has a large output but limited uses. The production of cyclohexylbenzene by hydrogenation of biphenyl has high economic benefits. Compared with other routes for producing cyclohexylbenzene, the selective hydrogenation of biphenyl has the advantages of simple reaction route, few side reactions, and no water in the product, and has broad application prospects. However, the current selective hydrogenation of biphenyl still has the problems of low biphenyl conversion rate and low cyclohexylbenzene selectivity. Summary of the invention

[0004] The main purpose of the present invention is to provide a catalyst which can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene when biphenyl is hydrogenated to produce cyclohexylbenzene.

[0005] The present invention also provides a method for preparing a catalyst, which can prepare the above catalyst with simple process and low cost.

[0006] The present invention also provides a method for preparing cyclohexylbenzene, which is obtained by selectively hydrogenating biphenyl using the above catalyst, thereby improving the conversion rate of biphenyl and the selectivity of cyclohexylbenzene.

[0007] In a first aspect, the present invention provides a catalyst comprising 2-5% nickel element by mass, and the remainder is copper-modified Beta molecular sieve.

[0008] The catalyst as described above comprises, by mass percentage, 5% nickel element and the remainder copper-modified Beta molecular sieve.

[0009] The catalyst as described above is prepared by a method comprising the following process:

[0010] The copper-modified Beta molecular sieve is impregnated with an aqueous solution containing a nickel source in equal volume, and the impregnation system is post-treated including drying and calcination to obtain the catalyst.

[0011] In a second aspect, the present invention provides a method for preparing the catalyst as described above, comprising the following steps:

[0012] 1) Adding aluminum source and silicon source to the template-alkaline solution in sequence to obtain a gel;

[0013] 2) adding a copper source solution to the gel to obtain a gel solution; wherein the adding speed of the copper source solution is controlled to be 3-5 ml / min;

[0014] 3) After the gel solution is crystallized, the crystallized product is post-treated including a first calcination treatment to obtain the copper-modified Beta molecular sieve;

[0015] 4) using an aqueous solution including a nickel source to perform an equal volume impregnation treatment on the copper-modified Beta molecular sieve to obtain an impregnation system;

[0016] 5) performing post-treatment including drying and second calcination on the impregnation system to obtain the catalyst.

[0017] In the method for preparing the catalyst as described above, the temperature of the crystallization treatment is 160-170° C. and the time is 24-48 hours.

[0018] In the above-mentioned method for preparing the catalyst, the temperature of the first calcination treatment is 500-600° C. and the time is 5-8 hours.

[0019] In the catalyst preparation method as described above, the equal volume impregnation treatment is carried out under ultrasound.

[0020] In a third aspect, the present invention provides a method for preparing cyclohexylbenzene, which is obtained by selectively hydrogenating biphenyl using the catalyst as described above or a catalyst obtained by the method for preparing the catalyst as described above.

[0021] The preparation method of cyclohexylbenzene as described above comprises the following steps:

[0022] 1) activating the catalyst using hydrogen to obtain an activated catalyst;

[0023] 2) At a temperature of 80-100° C. and a pressure of 0.5-2 MPa, hydrogen is introduced into a reaction kettle fixed with the activated catalyst and biphenyl to carry out a gas-solid contact reaction for 3-6 hours to obtain the cyclohexylbenzene.

[0024] In the above-mentioned method for preparing cyclohexylbenzene, the temperature of the activation treatment is 300-400° C. and the time is 0.5-1.5 h.

[0025] The catalyst provided by the present invention uses nickel as an active metal. The presence of copper in the copper-modified Beta molecular sieve can improve the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene when catalyzing the selective hydrogenation of biphenyl. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0027] In a first aspect, the present invention provides a catalyst comprising 2-5% nickel element by mass, and the remainder is copper-modified Beta molecular sieve.

[0028] The catalyst provided by the present invention includes 2-5% nickel element according to mass percentage, and the remainder is copper-modified Beta molecular sieve, which can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene in the process of catalytic biphenyl selective hydrogenation. It is speculated that it may be because the nickel element, as an active metal in the catalyst, has a high catalytic activity, which can effectively promote the selective hydrogenation of carbon-carbon double bonds in biphenyl molecules to generate cyclohexylbenzene; the copper-modified Beta molecular sieve is used as a carrier, and the copper element enters the skeleton of the Beta molecular sieve. The introduction of the copper element can inhibit the growth of nickel crystallites in the process of catalytic biphenyl selective hydrogenation, improve the dispersibility of metallic nickel, maintain the active surface area of ​​the catalyst, and thus improve the catalytic activity of the catalyst. Therefore, when the catalyst includes 2-5% nickel element according to mass percentage, and the remainder is copper-modified Beta molecular sieve, the catalyst has a high catalytic activity, can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene, and helps to reduce energy consumption and production costs, and improve economic benefits. When the mass percentage of nickel in the catalyst is not within 2-5%, and / or copper-modified Beta molecular sieve is not used as a carrier, the catalyst cannot play such a role, and thus cannot catalyze the selective hydrogenation of biphenyl to form cyclohexylbenzene or the selective hydrogenation of biphenyl to form cyclohexylbenzene, the conversion rate of biphenyl is low, and the selectivity of cyclohexylbenzene is low.

[0029] The catalyst provided by the present invention uses nickel as an active metal. The presence of copper in the copper-modified Beta molecular sieve can improve the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene when catalyzing the selective hydrogenation of biphenyl.

[0030] In some embodiments of the present invention, the catalyst comprises, by mass percentage, 5% nickel element and the remainder copper-modified Beta molecular sieve.

[0031] As a preferred solution, when the catalyst comprises, by mass percentage, 5% nickel element and the remainder copper-modified Beta molecular sieve, the conversion rate of biphenyl and the selectivity of cyclohexylbenzene can be further improved.

[0032] In some embodiments of the present invention, the catalyst is prepared by a method comprising the following process:

[0033] The copper-modified Beta molecular sieve is impregnated with an aqueous solution containing a nickel source in equal volume, and the impregnation system is post-treated including drying and calcination to obtain the catalyst.

[0034] In one embodiment, the nickel source can be dissolved in water and completely dissolved under stirring to form a nickel source solution, and then an equal volume of copper-modified Beta molecular sieve is added to the nickel source solution, and the equal volume impregnation treatment is performed for a certain time to uniformly disperse the nickel source on the copper-modified Beta molecular sieve to obtain an impregnation system. The impregnation system is then dried and calcined to obtain a copper-modified Beta molecular sieve loaded with active component nickel.

[0035] The method for preparing the catalyst of the present invention can prepare the catalyst of the first aspect of the present invention, and has a simple process and low cost.

[0036] In a second aspect, the present invention provides a method for preparing the catalyst as described above, comprising the following steps:

[0037] 1) Adding aluminum source and silicon source to the template-alkaline solution in sequence to obtain a gel;

[0038] 2) adding a copper source solution to the gel to obtain a gel solution; wherein the adding speed of the copper source solution is controlled to be 3-5 ml / min;

[0039] 3) After the gel solution is crystallized, the crystallized product is post-treated including a first calcination treatment to obtain the copper-modified Beta molecular sieve;

[0040] 4) using an aqueous solution including a nickel source to perform an equal volume impregnation treatment on the copper-modified Beta molecular sieve to obtain an impregnation system;

[0041] 5) performing post-treatment including drying and second calcination on the impregnation system to obtain the catalyst.

[0042] In step 1) of the present invention, optionally, the template agent can be an organic amine, preferably tetraethylammonium hydroxide; the alkaline solution can be at least one of sodium hydroxide and potassium hydroxide aqueous solutions, preferably sodium hydroxide solution; the aluminum source can be an aluminum salt, preferably aluminum nitrate; the silicon source can be selected from at least one of silicon dioxide, silicate, silica sol, silica gel, etc., preferably, the silicon source can be sodium metasilicate. Add the template agent tetraethylammonium hydroxide to the prepared sodium hydroxide alkaline solution, then add the aluminum source aluminum nitrate, stir until completely dissolved, then add the silicon source sodium metasilicate, stir at room temperature, and mix evenly to obtain a gel.

[0043] In step 2), optionally, the copper source may be a copper salt, preferably copper nitrate. Copper nitrate is dissolved in deionized water to form an aqueous solution containing copper nitrate, i.e., a copper source solution, and then the copper source solution is added to the gel obtained above, wherein the addition rate of the copper source solution is controlled to be 3-5 ml / min, so that the copper element can enter the framework structure of the Beta molecular sieve, replacing part of the silicon and aluminum therein, and the gel solution is obtained by stirring evenly.

[0044] In step 3), the gel solution obtained above is transferred to a stainless steel reactor containing a polytetrafluoroethylene liner, and the stainless steel reactor is placed in a constant temperature oven for crystallization to make the gel solution become a crystalline state. After the crystallization is completed, the crystallized product is subjected to a first calcination treatment, for example, the crystallized product is placed in a muffle furnace for a first calcination treatment to obtain a copper-modified Beta molecular sieve with the template agent removed.

[0045] In step 4), optionally, the nickel source may be a nickel salt, preferably nickel acetate tetrahydrate. Nickel acetate tetrahydrate may be dissolved in water and completely dissolved under stirring to form a nickel acetate tetrahydrate solution, and then an equal volume of copper-modified Beta molecular sieve is added to the nickel acetate tetrahydrate solution, and an equal volume impregnation treatment is performed for a certain period of time to uniformly disperse the metallic nickel on the copper-modified Beta molecular sieve to obtain an impregnation system.

[0046] In step 5), the impregnation system is post-treated to obtain a copper-modified Beta molecular sieve catalyst loaded with active metal nickel. The post-treatment includes drying and a second calcination treatment. The drying treatment can be carried out in an oven at 100-120°C. The second calcination treatment can be carried out in a muffle furnace, and the temperature of the second calcination treatment can be 550°C and the time can be 5h, which is used to remove volatile components in the copper-modified Beta molecular sieve carrier, form a stable structure, and enable the molecular sieve carrier to obtain a certain crystal form, grain size, pore structure and specific surface area, and obtain a copper-modified Beta molecular sieve catalyst loaded with active metal nickel, wherein the mass percentage of the nickel element is 2-5%, and the remainder is the copper-modified Beta molecular sieve.

[0047] The preparation method of the catalyst of the present invention can prepare the catalyst provided by the first aspect of the present invention, and the catalyst can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene. The preparation method is simple and easy to implement and is convenient for industrial scale-up production.

[0048] In some embodiments of the present invention, the crystallization treatment is performed at a temperature of 160-170° C. for 24-48 hours.

[0049] The temperature and time of the crystallization treatment in the present invention are within an appropriate range, which can fully crystallize the gel solution, avoid the crystallization temperature being too low, resulting in incomplete crystallization, and avoid the decomposition of certain substances due to excessively high temperature, which will have a certain impact on the structure of the crystallized product obtained by the crystallization treatment.

[0050] The temperature and time of the crystallization treatment in the present invention can fully transform the gel solution into a crystallized product with high efficiency.

[0051] In some embodiments of the present invention, the temperature of the first calcination treatment is 500-600° C. and the time is 5-8 hours.

[0052] The temperature and time of the first calcination treatment in the present invention are within an appropriate range, which can fully remove the template and volatile components, allow the copper element to fully enter the framework of the Beta molecular sieve, improve the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, and further improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene.

[0053] In some embodiments of the present invention, the equal volume immersion treatment is performed under ultrasound.

[0054] Optionally, the equal volume impregnation treatment can be carried out under ultrasound, using the high frequency vibration of ultrasound to evenly disperse the active component, i.e., metallic nickel, onto the copper-modified Beta molecular sieve, while overcoming the capillary resistance and entering the pores of the copper-modified Beta molecular sieve carrier, thereby improving the catalytic activity of the catalyst, and further improving the conversion rate of biphenyl and the selectivity of cyclohexylbenzene in the selective hydrogenation reaction of biphenyl.

[0055] In a third aspect, the present invention provides a method for preparing cyclohexylbenzene, which is obtained by selectively hydrogenating biphenyl using the catalyst as described above or a catalyst obtained by the method for preparing the catalyst as described above.

[0056] The present invention utilizes the catalyst provided in the first aspect or the catalyst prepared by the preparation method provided in the second aspect to selectively hydrogenate biphenyl to obtain cyclohexylbenzene, thereby improving the conversion rate of biphenyl and the selectivity of cyclohexylbenzene.

[0057] In some embodiments of the present invention, the preparation method comprises the following steps:

[0058] 1) activating the catalyst using hydrogen to obtain an activated catalyst;

[0059] 2) At a temperature of 80-100° C. and a pressure of 0.5-2 MPa, hydrogen is introduced into a reaction kettle fixed with the activated catalyst and biphenyl to carry out a gas-solid contact reaction for 3-6 hours to obtain the cyclohexylbenzene;

[0060] In the present invention, the catalyst is firstly activated by hydrogen in a tubular furnace for 1 hour to obtain an activated catalyst, and then biphenyl is selectively hydrogenated by the activated catalyst to obtain cyclohexylbenzene.

[0061] Specifically, in step 1), a certain amount of catalyst is placed in a high-pressure reactor under nitrogen protection, and the air in the reactor is fully replaced with nitrogen. After the air in the reactor is basically removed, the nitrogen in the reactor is replaced with hydrogen.

[0062] In step 2), the temperature of the reactor in which the activated catalyst and biphenyl are fixed is maintained in the range of 80-100° C., and the pressure is maintained in the range of 0.5-2 MPa. Then, hydrogen is introduced into the reactor to carry out gas-solid contact reaction with the catalyst for 3-6 hours. During the reaction, the hydrogen pressure decreases, and the hydrogen pressure is replenished to the starting pressure in time. Under the action of the catalyst, the carbon-carbon double bonds in the biphenyl molecules are selectively hydrogenated to generate cyclohexylbenzene.

[0063] The present invention uses the copper-modified Beta molecular sieve catalyst loaded with metallic nickel to catalyze the selective hydrogenation of biphenyl to obtain cyclohexylbenzene, and the catalyst has high activity, so the conversion rate of biphenyl and the selectivity of cyclohexylbenzene can be improved.

[0064] In some embodiments of the present invention, the activation treatment is carried out at a temperature of 300-400° C. and for a time of 0.5-1.5 h.

[0065] The temperature and time of the activation treatment in the present invention are relatively suitable, which can improve the catalytic activity of the catalyst and maintain the stability of the catalyst, thereby accelerating the reaction rate of converting biphenyl into cyclohexylbenzene and improving the conversion rate of biphenyl and the selectivity of cyclohexylbenzene.

[0066] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0067] Example 1

[0068] The preparation method of cyclohexylbenzene of the present embodiment comprises the following steps:

[0069] 1) First, 1.1g sodium hydroxide was dissolved in 80g deionized water to prepare a sodium hydroxide solution, and then 7.4g of a 40% tetraethylammonium hydroxide aqueous solution was dissolved in the sodium hydroxide solution, and 3.8g Al(NO3)3·9H2O was added. After stirring and dissolving completely, 57g Na2SiO3·9H2O was added, and the mixture was mixed evenly to form a gel. The copper nitrate solution was added dropwise to the above gel, wherein the addition rate of the copper nitrate solution was 3ml / min, and the gel solution was obtained after stirring evenly. The gel solution was transferred to a stainless steel reactor lined with polytetrafluoroethylene, placed in a constant temperature oven at 160℃ for crystallization for 24h. After the crystallization was completed, the solid product was separated by centrifugation, washed with deionized water, dried at 120℃, and subjected to the first calcination treatment at 550℃ in a muffle furnace for 8h to obtain a copper-modified Beta molecular sieve.

[0070] 2) Nickel was loaded on copper-modified Beta molecular sieve by equal volume impregnation method: 46.64g Ni(CH3COO)2·4H2O was dissolved in 100ml water, completely dissolved under stirring, 220g copper-modified Beta molecular sieve was added, ultrasonic impregnation was performed for 2h, drying was performed at 120℃, and a second calcination treatment was performed at 550℃ for 5h to obtain a copper-modified Beta molecular sieve catalyst loaded with active component Ni. The catalyst includes 5% nickel element and 95% copper-modified Beta molecular sieve by mass percentage.

[0071] 3) After 0.77 g of the above catalyst was reduced at 350° C. in a tubular furnace, it was placed in a high-pressure stirred kettle with 15.4 g of biphenyl under nitrogen protection, the seal was tightened, and the air in the reactor was fully replaced with nitrogen. After the air in the reactor was basically removed, the nitrogen in the reactor was replaced with hydrogen. After sufficient replacement, the hydrogen pressure was filled to 1 MPa, heating and stirring were turned on, the temperature was raised to 80° C., and the gas-solid contact reaction was started. After reacting for 4 hours, the heating and stirring were stopped, and the reactor was cooled to room temperature to obtain cyclohexylbenzene. The reactor was opened to collect the reaction liquid and analyzed by gas chromatograph. The results are shown in Table 1.

[0072] Example 2

[0073] The preparation method of cyclohexylbenzene in Example 2 is basically the same as that in Example 1, except that in step 2), 18.66 g of Ni(CH3COO)2·4H2O is dissolved in 100 ml of water, completely dissolved under stirring, and 220 g of copper-modified Beta molecular sieve is added. The prepared catalyst includes 2% nickel element and 98% copper-modified Beta molecular sieve in terms of mass percentage.

[0074] Example 3

[0075] The preparation method of cyclohexylbenzene in Example 3 is basically the same as that in Example 1, except that in step 2), 27.98 g of Ni(CH3COO)2·4H2O is dissolved in 100 ml of water and completely dissolved under stirring, and 220 g of copper-modified Beta molecular sieve is added. The prepared catalyst includes 3% nickel element and 97% copper-modified Beta molecular sieve in terms of mass percentage.

[0076] Example 4

[0077] The preparation method of cyclohexylbenzene in Example 4 is basically the same as that in Example 1, except that in step 2), 37.31 g of Ni(CH3COO)2·4H2O is dissolved in 100 ml of water and completely dissolved under stirring, and 220 g of copper-modified Beta molecular sieve is added. The prepared catalyst includes 4% nickel element and 96% copper-modified Beta molecular sieve in terms of mass percentage.

[0078] Example 5

[0079] The preparation method of cyclohexylbenzene in Example 5 is basically the same as that in Example 1, except that in step 1), the crystallization temperature is 170°C.

[0080] Example 6

[0081] The preparation method of cyclohexylbenzene in Example 6 is basically the same as that in Example 1, except that in step 1), the crystallization time is 48 hours.

[0082] Example 7

[0083] The preparation method of cyclohexylbenzene in Example 7 is basically the same as that in Example 1, except that in step 1), the temperature of the first calcination treatment is 600°C.

[0084] Example 8

[0085] The preparation methods of cyclohexylbenzene in Example 8 and Example 1 are basically the same, except that in step 1), the time of the first calcination treatment is 5 hours.

[0086] Example 9

[0087] The preparation method of cyclohexylbenzene in Example 9 is basically the same as that in Example 1, except that in step 3), the temperature of the gas-solid contact reaction is 100°C.

[0088] Example 10

[0089] The preparation method of cyclohexylbenzene in Example 10 is basically the same as that in Example 1, except that in step 3), the pressure of the gas-solid contact reaction is 2 MPa.

[0090] Embodiment 11

[0091] The preparation method of cyclohexylbenzene in Example 11 is basically the same as that in Example 1, except that in step 3), the time of gas-solid contact reaction is 6 hours.

[0092] Example 12

[0093] The preparation method of cyclohexylbenzene in Example 12 is basically the same as that in Example 1, except that in step 1), the addition rate of the copper nitrate solution is 5 ml / min.

[0094] Example 13

[0095] In this example, the catalyst after the reaction in Example 1 was filtered, washed, and dried, and then used to catalyze the selective hydrogenation reaction of biphenyl. This was repeated 20 times. The results of the 20th time are shown in Table 1.

[0096] Comparative Example 1

[0097] Comparative Example 1 is basically the same as the preparation method of cyclohexylbenzene in Example 1, except that in step 2), copper is loaded on the H-type Beta molecular sieve carrier by an equal volume impregnation method: 41.82g Cu(NO3)2·3H2O is dissolved in 100ml water, completely dissolved under stirring, 220g H-type beta molecular sieve is added, ultrasonic impregnation is performed for 2h, drying is performed at 120°C, and calcination is performed at 550°C for 5h to obtain a Beta molecular sieve catalyst loaded with active component Cu. Wherein, the catalyst includes 5% copper element and 95% H-Beta molecular sieve according to mass percentage.

[0098] Comparative Example 2

[0099] Comparative Example 2 is basically the same as the preparation method of cyclohexylbenzene in Example 1, except that in step 2), nickel is loaded on the H-type Beta molecular sieve carrier by an equal volume impregnation method: 46.64g Ni(CH3COO)2·4H2O is dissolved in 100ml water, completely dissolved under stirring, 220g H-type beta molecular sieve is added, ultrasonic impregnation is performed for 2h, drying is performed at 120℃, and calcination is performed at 550℃ for 5h to obtain a Beta molecular sieve catalyst loaded with active component Ni. Wherein, the catalyst includes 5% nickel element and 95% H-Beta molecular sieve according to mass percentage.

[0100] Comparative Example 3

[0101] Comparative Example 3 directly uses H-type Beta molecular sieve as a catalyst to catalyze the selective hydrogenation of biphenyl to prepare cyclohexylbenzene.

[0102] Table 1 Biphenyl conversion and cyclohexylbenzene selectivity of Examples 1-13 and Comparative Examples 1-3

[0103]

[0104] As can be seen from Table 1, compared with the comparative example, the catalyst provided by the present invention uses nickel as the active metal, and the presence of copper in the copper-modified Beta molecular sieve can improve the dispersibility of metallic nickel, thereby improving the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of biphenyl and the selectivity of cyclohexylbenzene when catalyzing the selective hydrogenation of biphenyl.

[0105] From the comparison between Examples 1-13 and Comparative Examples 1-3, it can be seen that the catalyst provided by the present invention uses nickel as an active metal and copper-modified Beta molecular sieve as a carrier, and when catalyzing the selective hydrogenation of biphenyl, the conversion rate of biphenyl and the selectivity of cyclohexylbenzene can be improved.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing cyclohexylbenzene, characterized in that: The catalyst comprising 2-5% nickel by mass and the remainder being copper-modified Beta molecular sieve is used to selectively hydrogenate biphenyl to obtain the product; Wherein, the catalyst is prepared by the following process: 1) Adding aluminum source and silicon source to the template-alkaline solution in sequence to obtain a gel; 2) adding a copper source solution to the gel to obtain a gel solution; wherein the adding speed of the copper source solution is controlled to be 3-5 ml / min; 3) After the gel solution is crystallized, the crystallized product is post-treated including a first calcination treatment to obtain the copper-modified Beta molecular sieve; 4) using an aqueous solution including a nickel source to perform an equal volume impregnation treatment on the copper-modified Beta molecular sieve to obtain an impregnation system; 5) performing post-treatment including drying and second calcination on the impregnation system to obtain the catalyst.

2. The method for preparing cyclohexylbenzene according to claim 1, characterized in that: The catalyst comprises, by mass percentage, 5% nickel element and the remainder copper-modified Beta molecular sieve.

3. The method for preparing cyclohexylbenzene according to claim 1, characterized in that: The temperature of the crystallization treatment is 160-170° C. and the time is 24-48 hours.

4. The method for preparing cyclohexylbenzene according to claim 3, characterized in that: The temperature of the first calcination treatment is 500-600° C. and the time is 5-8 hours.

5. The method for preparing cyclohexylbenzene according to claim 4, characterized in that: The equal volume immersion treatment is performed under ultrasound.

6. The method for preparing cyclohexylbenzene according to claim 1, characterized in that: The preparation method comprises the following steps: a) activating the catalyst using hydrogen to obtain an activated catalyst; b) introducing hydrogen into a reaction kettle fixed with the activated catalyst and biphenyl at a temperature of 80-100° C. and a pressure of 0.5-2 MPa for gas-solid contact reaction for 3-6 hours to obtain the cyclohexylbenzene.

7. The method for preparing cyclohexylbenzene according to claim 6, characterized in that: The activation treatment is carried out at a temperature of 300-400° C. and for a time of 0.5-1.5 h.

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