A catalyst for preparing ethylbenzene with high selectivity of n-octane and a preparation method and application thereof

Abstract

The application provides a catalyst for preparing ethylbenzene from n-octane with high selectivity, a preparation method and application thereof, and relates to the technical fields of catalysts and organic synthesis. The catalyst for preparing ethylbenzene from n-octane with high selectivity comprises a molecular sieve and a metal active component loaded in the molecular sieve crystal, wherein the metal active component comprises a main metal and an auxiliary metal, the main metal comprises one or more of Pd, Pt, Ru and Rh, and the auxiliary metal comprises one or more of Sn, Re, Ga, Zn and In. The catalyst provided by the application has high activity and good stability, can convert n-octane in low-value naphtha into high-value ethylbenzene with high selectivity, and opens up a new way for efficient preparation of ethylbenzene. The results of examples show that the service life of the catalyst in the reaction of preparing ethylbenzene from n-octane is more than 600 h, the conversion rate of n-octane is greater than 80%, the selectivity of ethylbenzene is more than 65%, and the total aromatic hydrocarbon selectivity is greater than 75%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst and organic synthesis, in particular to a catalyst for preparing ethylbenzene from n-octane with high selectivity and a preparation method and application thereof. BACKGROUND

[0002] Ethylbenzene is an important chemical raw material, which is mainly used for producing styrene in industry. Downstream products of ethylbenzene / styrene industry include styrene-butadiene rubber, ABS resin, polystyrene, etc., which are widely used in automobile manufacturing, building material production and electronic equipment manufacturing fields. In recent years, with the rapid development of downstream industries, the demand for ethylbenzene / styrene is increasing.

[0003] At present, the main source of ethylbenzene is the alkylation reaction of benzene and ethylene. American Mobil Company, BP Company, UOP Company, DuPont Company, as well as domestic Shanghai Oil Chemical Research Institute, Dalian Institute of Chemical Physics, Beijing Research Institute of Petroleum Science and other units and colleges and universities have successively studied the catalyst and technology for the alkylation reaction of benzene and ethylene. Although the production capacity of ethylbenzene has been increasing year by year in recent years, there is still a gap in the supply market of ethylbenzene, and the above-mentioned method for preparing ethylbenzene by alkylation reaction of benzene and ethylene has a relatively high raw material price. Therefore, it is of great research significance and practical value to develop a new reaction route for preparing ethylbenzene with high selectivity. SUMMARY

[0004] Therefore, the present application aims to provide a catalyst for preparing ethylbenzene from n-octane with high selectivity and a preparation method and application thereof. The catalyst provided by the present application can be used to prepare ethylbenzene from n-octane with high selectivity at a low cost.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a catalyst for preparing ethylbenzene from n-octane with high selectivity, which comprises a molecular sieve and a metal active component loaded in the crystal of the molecular sieve. The metal active component comprises a main metal and an auxiliary metal. The main metal comprises one or more of Pd, Pt, Ru and Rh, and the auxiliary metal comprises one or more of Sn, Re, Ga, Zn and In. The main metal and the auxiliary metal form an alloy nanocluster.

[0007] Preferably, the molecular sieve comprises ZSM-5, Silicalite-1 or Beta molecular sieve.

[0008] Preferably, the mass percentage of the molecular sieve, the main metal and the auxiliary metal in the catalyst is 90-99.6%, 0.2-5% and 0.2-5%, respectively.

[0009] The application provides a preparation method of the catalyst, comprising the following steps:

[0010] The silicon / aluminum source, the template agent, water and sodium hydroxide are mixed to obtain a molecular sieve mother liquor; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source;

[0011] The soluble precursor salt of the main metal, the soluble precursor salt of the auxiliary metal, water and the organic amine ligand are mixed to obtain a metal complex solution;

[0012] The molecular sieve mother liquor, the metal complex solution and the hydrogen peroxide are mixed to obtain a mixed solution;

[0013] The mixed solution is subjected to hydrothermal crystallization, and the obtained crystallization product is sequentially subjected to calcination and hydrogen reduction to obtain the catalyst.

[0014] Preferably, the silicon source comprises silica sol and / or tetraethyl orthosilicate; the aluminum source comprises one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate and sodium metaaluminate; the template agent comprises one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and triethylamine; and the organic amine ligand comprises one or more of 1,3-propanediamine, 1,4-butanediamine and 1,6-hexanediamine.

[0015] Preferably, when the silicon / aluminum source is a silicon source, the molar ratio of the template agent to the silicon source in the molecular sieve mother liquor is (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is (0.03-0.2):1; when the silicon / aluminum source is a silicon source and an aluminum source, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is greater than 100, the molar ratio of the template agent to the silicon source is (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is (0.03-0.2):1; the molar ratio of water to the silicon source in the mixed solution is greater than 18; the silicon source is calculated as SiO2, the aluminum source is calculated as Al, and the sodium hydroxide is calculated as Na.

[0016] Preferably, the mass of the main metal and the auxiliary metal in the metal complex solution is 0.2-5% and 0.2-5% of the mass of the silicon source in the molecular sieve mother liquor, respectively, and the silicon source is calculated as SiO2; the mass content of the organic amine ligand in the metal complex solution is 10-20%; the mass fraction of the hydrogen peroxide is 30%, and the mass content of the hydrogen peroxide in the mixed solution is 1-5%.

[0017] Preferably, the temperature of the hydrothermal crystallization is 150-170 DEG C, and the time is 24-96 h; the temperature of the calcination is 500-600 DEG C, and the time is 3-5 h, and the calcination is carried out under air condition; the temperature of the hydrogen reduction is 500-550 DEG C, and the time is 2-3 h.

[0018] The application provides application of the catalyst prepared by the preparation method in the preparation of ethylbenzene from n-octane with high selectivity.

[0019] Preferably, the reaction temperature for the preparation of ethylbenzene from n-octane with high selectivity is 530-550 DEG C, the reaction pressure is normal pressure, and the reaction space velocity is 0.5-4 h-1. -1 .

[0020] The application provides a catalyst for the preparation of ethylbenzene from n-octane with high selectivity, which comprises a molecular sieve and a metal active component loaded in the molecular sieve crystal, wherein the metal active component comprises a main metal and an auxiliary metal, the main metal comprises one or more of Pd, Pt, Ru and Rh, the auxiliary metal comprises one or more of Sn, Re, Ga, Zn and In, and the main metal and the auxiliary metal form an alloy nanocluster. In the application, the active metal (i.e. the main metal) and the auxiliary metal form an alloy nanocluster, which is located in the molecular sieve crystal and can catalyze the dehydrogenation of n-octane to generate octene, and the octene undergoes cyclization and intramolecular dehydrogenation in the limited pore channel of the molecular sieve to generate aromatic hydrocarbon with high selectivity. The catalyst provided by the application has high activity and good stability, can utilize n-octane in naphtha with low price to generate ethylbenzene through dehydrogenation and cyclization in the micropore of the molecular sieve, realizes the high-selectivity preparation of ethylbenzene, and thus realizes the high-selectivity conversion of n-octane in naphtha with low value into ethylbenzene with high value, thereby opening up a new way for the efficient preparation of ethylbenzene.

[0021] The application provides a preparation method of the catalyst, and the catalyst is prepared by one-step direct synthesis (i.e. mixing raw materials and hydrothermal crystallization), which is simple in process, low in cost and easy for industrial amplification.

[0022] The results of the examples show that the catalyst provided by the application has high stability and selectivity in the reaction of preparing ethylbenzene from n-octane, the service life can reach more than 600 h, the conversion rate of n-octane is greater than 80%, the selectivity of ethylbenzene is more than 65%, and the total aromatic hydrocarbon selectivity is greater than 75%. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The transmission electron microscope image of the Pt 1.0 Ga 1.0 / ZSM-5 catalyst obtained in Example 1;

[0024] Figure 2 The transmission electron microscope image of the Pt 1.0 Ga 1.0 / ZSM-5 catalyst obtained in Example 1; DETAILED DESCRIPTION

[0025] The application provides a catalyst for preparing ethylbenzene with high selectivity of n-octane, which comprises a molecular sieve and a metal active component loaded in the crystal of the molecular sieve, wherein the metal active component comprises a main metal and an auxiliary metal, the main metal comprises one or more of Pd, Pt, Ru and Rh, and the auxiliary metal comprises one or more of Sn, Re, Ga, Zn and In, and the main metal and the auxiliary metal form an alloy nanocluster.

[0026] In the application, the molecular sieve preferably comprises ZSM-5, Silicalite-1 or Beta molecular sieve; the main metal preferably is Pt; and the auxiliary metal preferably is Ga, In or Zn.

[0027] The application further provides a preparation method of the catalyst.

[0028] The silicon / aluminum source, a template agent, water and sodium hydroxide are mixed to obtain a molecular sieve mother liquor; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source;

[0029] The soluble precursor salt of the main metal, the soluble precursor salt of the auxiliary metal, water and an organic amine ligand are mixed to obtain a metal complex solution;

[0030] The molecular sieve mother liquor, the metal complex solution and hydrogen peroxide are mixed to obtain a mixed solution;

[0031] The mixed solution is subjected to hydrothermal crystallization, and the obtained crystallization product is sequentially subjected to calcination and hydrogen reduction to obtain the catalyst.

[0032] In the application, the raw materials involved are all commercially available goods well known to those skilled in the art, unless otherwise specified.

[0033] The silicon / aluminum source, a template agent, water and sodium hydroxide are mixed to obtain a molecular sieve mother liquor. In the application, the silicon / aluminum source is a silicon source or a silicon source and an aluminum source. In the application, the silicon source preferably comprises silica sol and / or tetraethyl orthosilicate (TEOS); the aluminum source preferably comprises one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate and sodium metaaluminate; and the template agent preferably comprises one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and triethylamine.

[0034] In the present application, the method for mixing the silicon / aluminum source, the template agent, water and sodium hydroxide is preferably as follows: the template agent and water are mixed to obtain a template agent aqueous solution; the silicon / aluminum source is added into the template agent aqueous solution and stirred uniformly, and then sodium hydroxide is added into the solution and stirred uniformly.

[0035] In the present application, the mass concentration of the template agent aqueous solution is preferably 25%. In the present application, when the silicon / aluminum source is a silicon source and an aluminum source, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is preferably greater than 100, the molar ratio of the template agent to the silicon source is preferably (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is preferably (0.03-0.2):1. In the present application, when the molecular sieve in the catalyst is ZSM-5 molecular sieve, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is further preferably greater than 150, the molar ratio of the template agent to the silicon source is further preferably (0.1-0.2):1, and the molar ratio of sodium hydroxide to the silicon source is further preferably (0.1-0.2):1; when the molecular sieve in the catalyst is Beta molecular sieve, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is preferably greater than 100, the molar ratio of the template agent to the silicon source is further preferably (0.15-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is further preferably (0.15-0.2):1. In the present application, when the silicon / aluminum source is a silicon source, the molar ratio of the template agent to the silicon source in the molecular sieve mother liquor is preferably (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is preferably (0.03-0.2):1; when the molecular sieve in the catalyst is Silicalite-1 molecular sieve, the molar ratio of the template agent to the silicon source in the molecular sieve mother liquor is further preferably (0.15-0.25):1. In the present application, the silicon source is calculated as SiO2, the aluminum source is calculated as Al, and the sodium hydroxide is calculated as Na.

[0036] In the present application, the soluble precursor salt of the main metal, the soluble precursor salt of the auxiliary metal, water and the organic amine ligand are mixed to obtain a metal complex solution. In the present application, the soluble precursor salt of the main metal is preferably a soluble chlorate salt of the main metal, and the soluble precursor salt of the auxiliary metal is preferably a soluble nitrate salt or chlorate salt of the auxiliary metal; the organic amine ligand preferably includes one or more of 1,3-propanediamine, 1,4-butanediamine and 1,6-hexanediamine.

[0037] In the present application, the mass of the main metal and the auxiliary metal in the metal complex solution is preferably 0.2-5% and 0.2-5% of the mass of the silicon source in the molecular sieve mother liquor respectively, and more preferably 0.5-2% and 0.5-2% respectively, the silicon source being calculated as SiO2.

[0038] In the present application, the method for mixing the soluble precursor salt of the main metal, the soluble precursor salt of the auxiliary metal, water and the organic amine ligand is preferably dissolving the soluble precursor salt of the main metal and the soluble precursor salt of the auxiliary metal in water, and adding the organic amine ligand to the obtained mixed metal salt solution.

[0039] After obtaining the molecular sieve mother liquor and the metal complex solution, the present application mixes the molecular sieve mother liquor, the metal complex solution and hydrogen peroxide to obtain a mixed solution. The present application introduces metal elements in the form of metal complex, which is convenient for the metal to enter the interior of the molecular sieve crystal during crystallization. In the present application, the mass fraction of the hydrogen peroxide is preferably 30%, and the mass content of the hydrogen peroxide in the mixed solution is preferably 1-5%, more preferably 1.5-3.5%, and further preferably 2-2.5%. In the present application, the hydrogen peroxide plays a role in stabilizing the complex solution. In the present application, the molar ratio of water to silicon source in the mixed solution is preferably greater than 18; when the molecular sieve in the catalyst is ZSM-5 molecular sieve, the molar ratio of water to silicon source in the mixed solution is further preferably greater than 25; when the molecular sieve in the catalyst is Beta molecular sieve, the molar ratio of water to silicon source in the mixed solution is further preferably greater than 20; the silicon source being calculated as SiO2.

[0040] In the present application, the method for mixing the molecular sieve mother liquor, the metal complex solution and hydrogen peroxide is preferably adding the metal complex solution dropwise into the molecular sieve mother liquor, stirring uniformly, and then adding hydrogen peroxide thereto and stirring uniformly.

[0041] After obtaining the mixed solution, the present application performs hydrothermal crystallization on the mixed solution, and then performs calcination and hydrogen reduction on the obtained crystallization product in sequence to obtain the catalyst. In the present application, the temperature of the hydrothermal crystallization is preferably 150-170°C, and the time is preferably 24-96h, and more preferably 72-96h. In the present application, the hydrothermal crystallization mainly involves a crystallization reaction of the molecular sieve. After the hydrothermal crystallization is completed, the obtained crystallization reaction solution is preferably filtered, solid-phase washed and dried in sequence to obtain the crystallization product.

[0042] In the present application, the calcination temperature is preferably 500-600°C, more preferably 550-560°C, and the calcination time is preferably 3-5h, more preferably 4-5h, and the calcination is preferably carried out in air. During the calcination, the template in the molecular sieve channels is removed, water is removed, and a high-temperature solid-state crystallization reaction of the molecular sieve occurs. At the same time, the organic amine ligand is decomposed and oxidized to generate nitrogen oxides, and the metal ions are converted into oxides and stored inside the molecular sieve crystals.

[0043] In the present application, the hydrogen reduction temperature is preferably 500-550°C, the temperature is preferably constant, the temperature rising rate from room temperature to the hydrogen reduction temperature is preferably 2-5°C / min, the hydrogen reduction time is preferably 2-3h, and the hydrogen reduction is preferably carried out in a pure hydrogen atmosphere. During the hydrogen reduction, the metal oxides inside the molecular sieve crystals are reduced to alloys.

[0044] The present application provides the use of the catalyst prepared by the above technical scheme or the preparation method in the high-selectivity preparation of ethylbenzene from n-octane. In the present application, the reaction temperature for the high-selectivity preparation of ethylbenzene from n-octane is preferably 530-550°C, the reaction pressure is preferably normal pressure, the reaction space velocity is preferably 0.5-4h -1 , more preferably 2h -1 , and the reaction is preferably carried out in a fixed bed reactor, i.e. after the n-octane is gasified, it enters the fixed bed reactor. The catalyst provided by the present application has high activity and good stability, and can utilize the cheap n-octane in naphtha to generate ethylbenzene through dehydrogenation and cyclization (i.e. aromatization reaction) in the micropores of the molecular sieve, thereby realizing the high-selectivity preparation of ethylbenzene.

[0045] In order to further illustrate the present application, the catalyst for the high-selectivity preparation of ethylbenzene from n-octane, the preparation method and the use thereof provided by the present application are described in detail below with examples, but they should not be understood as limiting the scope of protection of the present application.

[0046] Example 1

[0047] (a) 22.4g of silica sol (silica mass fraction 30%) and 0.03g of aluminum nitrate were added to 24.0g of 25wt% tetrapropylammonium hydroxide aqueous solution, and 0.8g of sodium hydroxide was added after uniform stirring, and the mixture was continuously stirred until uniform;

[0048] (b) 0.179g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.266g of gallium nitrate 4.5 hydrate (gallium content 25.3%) were dissolved in 10g of water, 2.5g of 1,3-propylenediamine was added to the solution, and the mixture was stirred until a transparent solution was formed;

[0049] (c) Add the solution obtained in (b) dropwise to the solution obtained in (a), stir until homogeneous, then add 2.0 g of 30% hydrogen peroxide and stir until homogeneous;

[0050] (d) The sol obtained in (c) was transferred to a 100 mL crystallization vessel and crystallized at 170 °C for 72 h. After filtration and washing, it was calcined at 560 °C in air for 5 h. Before use, it was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 5 °C / min from room temperature to 550 °C and then reduced at this temperature for 2 h to obtain Pt. 1.0 Ga 1.0 / ZSM-5 finished catalyst (i.e., the mass percentage of Pt and Ga in the catalyst is 1.0% each).

[0051] Figure 1 For Pt 1.0 Ga 1.0 Transmission electron microscopy image of the ZSM-5 catalyst, showing that the noble metal is uniformly dispersed inside the molecular sieve crystals with a grain size of 2–5 nm.

[0052] Pt 1.0 Ga 1.0 / ZSM-5 catalyst was used for the aromatization of n-octane to prepare ethylbenzene, and the activated Pt 1.0 Ga 1.0 The reaction was initiated by introducing ZSM-5 catalyst into the reactants. Reaction conditions: catalyst charge 2g, reaction temperature 550℃, reaction pressure atmospheric pressure, and reaction space velocity 2h⁻¹. -1 For specific catalytic effects, please refer to [link / reference]. Figure 2 See Table 1.

[0053] Example 2

[0054] (a) Take 20.8g of tetraethyl orthosilicate and add it to 30.0g of 25wt% tetrapropylammonium hydroxide aqueous solution. After stirring evenly, add 0.7g of sodium hydroxide and continue stirring evenly for later use.

[0055] (b) Dissolve 0.08 g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.079 g of indium(III) nitrate hydrate (indium content 38.2%) in 20 g of water, add 2.5 g of 1,4-butanediamine, and stir until a clear solution is formed;

[0056] (c) Add the solution obtained in (b) dropwise to the solution obtained in (a), stir until homogeneous, then add 1.85g of 30% hydrogen peroxide and stir until homogeneous;

[0057] (d) The sol obtained in (c) was transferred into a 100 mL crystallization kettle, crystallized at 170°C for 96 h, filtered, washed, calcined at 560°C for 4 h under air, and activated by on-line reduction before use, with pure hydrogen as the reaction atmosphere, a heating rate of 2°C / min, and a reduction temperature of 550°C for 2 h. The Pt 0.5 In 0.5 The finished Pt

[0058] The Pt 0.5 In 0.5 The Pt 0.5 In 0.5 The finished Pt -1 The specific catalytic effect is shown in Table 1.

[0059] Example 3

[0060] (a) 20.8 g of silica sol (30% by mass of Si02) and 0.050 g of aluminum sulfate were added to 12.0 g of 25% by mass aqueous tetraethylammonium hydroxide solution, and 0.7 g of sodium hydroxide was added after uniform stirring. The mixture was stirred until uniform.

[0061] (b) 0.167 g of chloroplatinic acid hexahydrate (37.5% by mass of Pt) and 0.572 g of zinc nitrate hexahydrate (21.8% by mass of Zn) were dissolved in 15 g of water, and 2.5 g of 1,3-propanediamine was added to the solution. The mixture was stirred until uniform to form a transparent solution.

[0062] (c) The solution obtained in (b) was added dropwise to the solution obtained in (a), and 1.0 g of 30% hydrogen peroxide was added after uniform stirring.

[0063] (d) The sol obtained in (c) was transferred into a 100 mL crystallization kettle, crystallized at 150°C for 96 h, filtered, washed, calcined at 560°C for 3 h under air, and activated by on-line reduction before use, with pure hydrogen as the reaction atmosphere, a heating rate of 3°C / min, and a reduction temperature of 530°C for 2 h. The Pt 1.0 Zn 2.0 The finished Pt

[0064] The Pt 1.0 Zn 2.0Beta catalyst for n-octane aromatization reaction to prepare ethylbenzene, Pt 1.0 Zn 2.0 Beta catalyst for n-octane aromatization reaction to prepare ethylbenzene, Pt -1 The specific catalytic effect is shown in Table 1.

[0065] Example 4

[0066] (a) 22.4 g of silica sol (silica mass fraction 30%) and 0.02 g of sodium metaaluminate were added to 24.0 g of 25 wt% tetrapropylammonium hydroxide aqueous solution, and after uniform stirring, 0.4 g of sodium hydroxide was added, and uniform stirring was continued for standby;

[0067] (b) 0.174 g of ruthenium chloride trihydrate (ruthenium content 38.7%) and 0.154 g of zinc nitrate hexahydrate (zinc content 21.8%) were dissolved in 15 g of water, 1.8 g of 1,3-propanediamine was added thereto, and stirred to form a transparent solution;

[0068] (c) The solution obtained in (b) was added dropwise to the solution obtained in (a), and stirred uniformly, and then 1.5 g of 30% concentration hydrogen peroxide was added, and stirred uniformly;

[0069] (d) The sol obtained in (c) was transferred into a 100 mL crystallization kettle, and crystallized at 170°C for 72 h, filtered, washed, and calcined at 560°C under air for 4 h, and before use, on-line reduction was performed, the reaction atmosphere was pure hydrogen, the temperature was raised at a rate of 2°C / min from room temperature to 550°C, and reduction was performed at constant temperature for 2 h, to obtain Ru 1.0 Zn 0.5 / ZSM-5 finished catalyst (i.e. the mass percentage contents of Ru and Zn in the catalyst are 1.0% and 0.5%, respectively).

[0070] Ru 1.0 Zn 0.5 / ZSM-5 catalyst for n-octane aromatization reaction to prepare ethylbenzene, Pt 1.0 Zn 0.5 / ZSM-5 catalyst for n-octane aromatization reaction to prepare ethylbenzene, Pt -1 The specific catalytic effect is shown in Table 1.

[0071] Table 1 Catalytic effect of catalysts for n-octane aromatization reaction in Examples 1-4

[0072]

[0073] The above merely describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. Use of a catalyst in the preparation of ethylbenzene from n-octane with high selectivity, the catalyst comprising a molecular sieve and a metal active component loaded inside the molecular sieve crystals, the metal active component comprising a main metal and an auxiliary metal, the main metal comprising one or more of Pd, Pt, Ru and Rh, the auxiliary metal comprising one or more of Sn, Re, Ga, Zn and In, the main metal and the auxiliary metal forming alloy nanoclusters; a preparation method of the catalyst comprising the following steps: mixing a silicon / aluminum source, a template agent, water and sodium hydroxide to obtain a molecular sieve mother liquor; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source; mixing a soluble precursor salt of the main metal, a soluble precursor salt of the auxiliary metal, water and an organic amine ligand to obtain a metal complex solution; mixing the molecular sieve mother liquor, the metal complex solution and hydrogen peroxide to obtain a mixed solution; subjecting the mixed solution to hydrothermal crystallization, and then subjecting the obtained crystallization product to calcination and hydrogen reduction in sequence to obtain the catalyst.

2. Use according to claim 1, characterized in that, The molecular sieve comprises ZSM-5, Silicalite-1 or Beta molecular sieve.

3. Use according to claim 1 or 2, characterized in that, The mass percentage contents of the molecular sieve, the main metal and the auxiliary metal in the catalyst are 90-99.6%, 0.2-5% and 0.2-5% respectively.

4. Use according to claim 1, characterized in that, The silicon source comprises silica sol and / or tetraethyl orthosilicate; the aluminum source comprises one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate and sodium metaaluminate; the template agent comprises one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and triethylamine; and the organic amine ligand comprises one or more of 1,3-propanediamine, 1,4-butanediamine and 1,6-hexanediamine.

5. Use according to claim 1 or 4, characterized in that, When the silicon / aluminum source is a silicon source, the molar ratio of the template agent to the silicon source in the molecular sieve mother liquor is (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is (0.03-0.2):1; when the silicon / aluminum source is a silicon source and an aluminum source, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is greater than 100, the molar ratio of the template agent to the silicon source is (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is (0.03-0.2):1; the molar ratio of water to the silicon source in the mixed solution is greater than 18; the silicon source is calculated as SiO2, the aluminum source is calculated as Al, and the sodium hydroxide is calculated as Na.

6. Use according to claim 1, characterized in that, The mass of the main metal and the auxiliary metal in the metal complex solution is 0.2-5% and 0.2-5% of the mass of the silicon source in the molecular sieve mother liquor respectively, the silicon source being calculated as SiO2; the mass content of the organic amine ligand in the metal complex solution is 10-20%; the mass fraction of the hydrogen peroxide is 30%, and the mass content of the hydrogen peroxide in the mixed solution is 1-5%.

7. The use according to claim 1, characterized in that, The temperature of the hydrothermal crystallization is 150-170°C, and the time is 24-96h; the temperature of the calcination is 500-600°C, and the time is 3-5h, the calcination being performed in air; the temperature of the hydrogen reduction is 500-550°C, and the time is 2-3h.

8. The use according to claim 1, characterized in that, The reaction temperature for preparing ethylbenzene with high selectivity of n-octane is 530-550℃, the reaction pressure is normal pressure, and the reaction space velocity is 0.5-4h -1 .

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