Bifunctional catalyst for preparing 2-methylnaphthalene or 2, 6-dimethylnaphthalene through alkylation of synthesis gas and naphthalene as well as preparation method and application of bifunctional catalyst

Abstract

The invention discloses a bifunctional catalyst for preparing 2-methylnaphthalene or 2, 6-dimethylnaphthalene through alkylation of synthesis gas and naphthalene as well as a preparation method and application of the bifunctional catalyst, and the bifunctional catalyst comprises a metal monatomic supported catalyst and a molecular sieve, wherein the metal monatomic supported catalyst comprises In2O3 and one of metals of Cu, Pd, Rh and Pt which are supported on the In2O3. According to the present invention, the metal monatomic supported catalyst has excellent catalytic performance in the alkylation reaction of the synthesis gas and the naphthalene, and has the 100% atom utilization rate, the adjustable microstructure and the extremely high methylation intermediate selectivity; meanwhile, the metal monatomic supported catalyst has strong interaction between a metal active center and a carrier, loss of active components is not prone to occurring, the modified zeolite molecular sieve has milder acidity, the stability of the catalyst is greatly improved through the characteristics, and the metal monatomic supported catalyst has the advantages of being high in conversion efficiency and good in product selectivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of the reaction for alkylating polycyclic aromatic hydrocarbons into high-value-added chemicals, and particularly relates to a bifunctional catalyst for synthesizing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of syngas and naphthalene, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of coal chemical industry and petrochemical industry, the development of synthesizing 2-methylnaphthalene and 2,6-dimethylnaphthalene from naphthalene as raw materials can not only increase the added value of naphthalene, but also reduce the production cost of 2,6-dimethylnaphthalene, laying a foundation for industrial application.

[0003] 2-Methylnaphthalene and 2,6-dimethylnaphthalene are important raw materials for synthesizing polymeric materials with excellent properties. Among them, 2-methylnaphthalene is used as an intermediate for producing vitamin K3 in medicine, oxidized to prepare β-naphthol, and used as a long-acting or short-acting oral contraceptive. In agriculture, it is used to synthesize plant growth regulators and DDT emulsifiers; after sulfonation, it can be used as a detergent, and can also be used as a raw material for fiber dyeing assistants, wetting agents, surfactants, pesticides, etc.; 2,6-dimethylnaphthalene (2,6-DMN) is an important raw material for synthesizing polymeric materials with excellent properties. The corresponding 2,6-naphthalenedicarboxylic acid (2,6-NDCA) formed after its oxidation and the ethylene glycol condensate 2,6-naphthalenedicarboxylic acid ethylene glycol ester (PEN) are a new type of polyester material. Compared with the traditionally used polyethylene terephthalate (PET), PEN has better gas barrier properties, heat resistance, chemical stability, and radiation resistance, and can be widely used in the manufacturing industries of fibers, electronic components, building components, instruments, insulating materials, photographic films, magnetic tapes, food packaging films, beer bottles, and aerospace and atomic energy materials, etc. It has great development potential and is the fastest-growing polymer material in the past decade. The traditional process route for methylation of methanol and naphthalene is to directly alkylate methanol and naphthalene on a molecular sieve catalyst. Although this technical route is relatively mature, there are the following problems: The self-reaction of methanol (such as methanol to olefins) is easier to proceed than the methylation of methanol and naphthalene, resulting in a large amount of methanol not participating in the methylation reaction, causing a low single-pass conversion rate of naphthalene, and methanol is prone to generate a large amount of carbonaceous precursors such as light olefins under the action of the catalyst, making the catalyst prone to carbon deposition and deactivation. Summary of the Invention

[0004] To overcome the problem that the catalyst is prone to deactivation in the process of methylation of methanol and naphthalene in the prior art, the purpose of the present invention is to provide a bifunctional catalyst for synthesizing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of syngas and naphthalene, a preparation method thereof, and an application thereof. The catalyst prepared by this method has good catalytic activity.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A bifunctional catalyst for the alkylation of syngas with naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene, comprising a metal single-atom supported catalyst and a molecular sieve;

[0007] Among them, the metal single-atom supported catalyst includes In2O3 and one metal among Cu, Pd, Rh, and Pt supported on In2O3.

[0008] Furthermore, the mass ratio of the molecular sieve to the metal single-atom supported catalyst is 3:7 to 7:3.

[0009] Furthermore, the mass percentage content of the single-atom metal supported in the metal single-atom supported catalyst is 0.1% to 1%.

[0010] Furthermore, the metal single-atom supported catalyst is prepared through the following process:

[0011] One of copper nitrate, palladium nitrate, rhodium nitrate, and platinum chloride is ball-milled with indium nitrate and urea and then calcined to obtain the metal single-atom supported catalyst.

[0012] Furthermore, the ball milling is carried out at a rotation speed of 50 Hz for 0.5 - 4 h;

[0013] The molar ratio of one of copper nitrate, palladium nitrate, rhodium nitrate, and platinum chloride, indium nitrate, and urea is (0.00001 - 0.0005):(0.01 - 0.1):(0.01 - 0.1);

[0014] The calcination temperature is 400 - 600 °C and the time is 4 - 6 h.

[0015] Furthermore, the molecular sieve is a SAPO-11 molecular sieve, or the molecular sieve is prepared through the following process: The SAPO-11 molecular sieve is immersed in a solution of zinc nitrate, gallium nitrate, cerium nitrate, or lanthanum nitrate, left standing and then dried and calcined to obtain the modified molecular sieve.

[0016] Furthermore, the loading amount of zinc, gallium, cerium, or lanthanum is 1% - 3% of the mass of the molecular sieve;

[0017] The calcination temperature is 400 - 600 °C and the time is 3 - 5 h.

[0018] A preparation method of a bifunctional catalyst for the alkylation of syngas with naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene, comprising the following steps:

[0019] Mix the metal single-atom supported catalyst and the molecular sieve and press them into tablets to obtain a bifunctional catalyst for the alkylation of syngas with naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene.

[0020] Application of a bifunctional catalyst in the one-step synthesis of 2-methylnaphthalene or 2,6-dimethylnaphthalene from syngas and naphthalene.

[0021] Furthermore, the catalyst is added to a fixed-bed reactor, and then syngas and naphthalene are introduced. The reaction is carried out at a pressure of 1-5 MPa and a temperature of 300-550 °C to produce 2-methylnaphthalene or 2,6-dimethylnaphthalene; the volume ratio of carbon monoxide to hydrogen in the syngas is (0.1-8):1, and the volume space velocity of the syngas is 1000-50000 h -1 ; the mass space velocity of naphthalene is 0.1-5 h -1 .

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The catalyst in the present invention includes a metal single-atom supported catalyst and a molecular sieve. Among them, the metal single-atom supported catalyst exhibits excellent CO adsorption activation ability and hydrogenolysis ability. The isolated metal and the support on the metal single-atom supported catalyst can both serve as active sites for H2 dissociation, thereby increasing the local concentration of active H* species and greatly increasing the concentration of methyl intermediates. At the same time, the metal single-atom supported catalyst has a strong interaction between the metal active center and the support, and it is not easy to cause the loss of active components. In addition, the molecular sieve has a milder acidity. These characteristics greatly extend the stability of the catalyst. In combination with the molecular sieve, the strong acid strength can be weakened, and the conversion of naphthalene can be enhanced; at the same time, the deep alkylation reaction of the product can be inhibited, and the selectivity of methylnaphthalene can be effectively improved. At the same time, the modified molecular sieve has a more reasonable acid site distribution, which is beneficial to improving the selectivity of 2-methylnaphthalene / 2,6-dimethylnaphthalene.

[0024] The present invention uses syngas instead of methanol as the methylation reagent, and it is efficiently converted with naphthalene on the catalyst prepared in the present invention. The main route is to convert syngas into active intermediates such as methanol on the metal single-atom supported catalyst, and then carry out a methylation reaction with naphthalene on the acidic sites of the zeolite molecular sieve. Therefore, using syngas and naphthalene for methylation reaction to produce high-value-added chemicals has the advantages of a short process route, high naphthalene conversion rate, high catalyst stability, and high selectivity of the target product, and is more economical and efficient. In the present invention, syngas as an alkylation reagent can greatly reduce the reaction concentration of the alkylation reagent, in-situ generate methanol intermediates on the metal oxide, and in-situ consume the intermediates, inhibiting methanol side reactions and greatly extending the catalyst life. In the present invention, the raw material syngas for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene has low cost, wide sources, a simple and efficient process route, and significant economic advantages; there is no three-waste discharge and the process is pollution-free. Using syngas as the raw material, there are fewer by-products such as polyalkylated aromatics, the reactant composition is simple, which is conducive to separation and purification, and the product selectivity is high. Detailed implementation manners

[0025] The present invention will be further described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited to these embodiments only.

[0026] A bifunctional catalyst for the alkylation of syngas with naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene according to the present invention is a "metal single atom - zeolite" bifunctional catalyst composed of a metal single atom supported catalyst and a modified zeolite molecular sieve. Among them, the mass percentage content of the metal single atom supported catalyst is 30% - 70%, and the rest is the modified zeolite molecular sieve.

[0027] The metal single atom supported catalyst component can be a metal single atom supported catalyst composed of one metal among Cu, Pd, Rh, and Pt and In2O3.

[0028] The metal single atom supported catalyst is prepared by the ball milling method.

[0029] The bifunctional catalyst for the alkylation of syngas with naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene according to the present invention includes the following steps:

[0030] Preparation of the metal single atom supported catalyst by the mechanical ball milling method:

[0031] 1) Preparation of the Cu / In2O3 metal single atom supported catalyst by the mechanical ball milling method

[0032] Step 1: Put 0.00001 - 0.0005 of copper nitrate, 0.01 - 0.1 mol of indium nitrate, and 0.01 - 0.1 mol of urea into the ball milling tank;

[0033] Step 2: Conduct mechanical ball milling for 0.5 - 4 h;

[0034] Step 3: Calcine the ball milled product at 400 - 600 °C for 3 - 5 h to obtain the Cu / In2O3 metal single atom supported catalyst.

[0035] Replace copper nitrate in the above steps with palladium nitrate to obtain Pd / In2O3, replace copper nitrate with rhodium nitrate to obtain Rh / In2O3, and replace copper nitrate with platinum chloride to obtain Pt / In2O3. Specifically,

[0036] Pd / In2O3 is obtained through the following process: Put palladium nitrate, indium nitrate, and urea into the ball milling tank, then react at a rotation speed of 50 Hz for 2 - 4 h, and then calcine at 400 - 600 °C for 4 - 6 h to obtain Pd / In2O3. Among them, the molar ratio of palladium nitrate, indium nitrate, and urea is (0.00004 - 0.0004):(0.01 - 0.1):(0.01 - 0.1).

[0037] Rh / In2O3 is prepared through the following process: rhodium nitrate, indium nitrate and urea are put into a ball milling tank, and then reacted at a rotation speed of 50 Hz for 2 - 4 h, and then calcined at 400 - 600 °C for 4 - 6 h to obtain Rh / In2O3. Among them, the molar ratio of rhodium nitrate, indium nitrate and urea is (0.00004 - 0.0004):(0.01 - 0.1):(0.01 - 0.1).

[0038] Pt / In2O3 is prepared through the following process: platinum chloride, indium nitrate and urea are put into a ball milling tank, and then reacted at a rotation speed of 50 Hz for 2 - 4 h, and then calcined at 400 - 600 °C for 4 - 6 h to obtain Pt / In2O3. Among them, the molar ratio of platinum chloride, indium nitrate and urea is (0.00002 - 0.0002):(0.01 - 0.1):(0.01 - 0.1).

[0039] 2) Preparation of modified zeolite molecular sieve:

[0040] The SAPO-11 molecular sieve is immersed in a zinc nitrate, gallium nitrate, cerium nitrate or lanthanum nitrate solution with a concentration of 0.0001 - 0.001 mol / L, left standing for 1 - 2 h and then dried, and then calcined at 400 - 600 °C for 3 - 5 h to obtain a modified molecular sieve; among them, the loading amount of zinc, gallium, cerium or lanthanum element is 1% - 3% of the mass of the molecular sieve.

[0041] 3) Mix the metal single-atom supported catalyst and the molecular sieve according to a mass ratio of 3:7 to 7:3, and tablet them to obtain a bifunctional catalyst for the alkylation of syngas and naphthalene to prepare 2-methylnaphthalene or 2,6-dimethylnaphthalene.

[0042] The application of the bifunctional catalyst prepared by the above method in the one-step synthesis of 2-methylnaphthalene / 2,6-dimethylnaphthalene from syngas and naphthalene in a fixed-bed reactor, and the application method is: adding the catalyst into the fixed-bed reactor, and then introducing syngas and naphthalene, reacting at a reaction temperature of 300 - 550 °C and a reaction pressure of 1 - 5 MPa to generate 2-methylnaphthalene or 2,6-dimethylnaphthalene.

[0043] Among them, the volume ratio of carbon monoxide to hydrogen in the syngas is (0.1 - 8):1, and the volume space velocity of the syngas is 1000 - 50000 h -1 ; the mass space velocity of naphthalene is 0.1 - 5 h -1 . The bifunctional catalytic reaction of the bifunctional catalyst for the reaction of syngas and naphthalene to generate 2-methylnaphthalene / 2,6-dimethylnaphthalene is carried out in a fixed-bed reactor.

[0044] Preparation of bifunctional catalyst:

[0045] Select a metal single-atom supported catalyst (such as one of Cu / In2O3, Pd / In2O3, Rh / In2O3, and Pt / In2O3, etc.) and mix it with a modified molecular sieve, and tablet it into 20-40 mesh to obtain a catalyst for the one-step synthesis of 2-methylnaphthalene / 2,6-dimethylnaphthalene from syngas and naphthalene, that is, a "metal single-atom - zeolite" bifunctional catalyst.

[0046] In the present invention, syngas is used as an alkylating agent, which effectively reduces the concentration of methylation intermediates, inhibits side reactions of intermediates, enables in-situ generation and in-situ consumption of methylation intermediates. At the same time, the metal single-atom supported catalyst has a strong interaction between the metal active center and the carrier, and it is not easy to lose the active components. Moreover, the modified zeolite molecular sieve has a milder acidity. These characteristics greatly extend the stability of the catalyst. Therefore, using the methylation reaction of syngas and naphthalene to produce high-value-added chemicals has the advantages of a short process route, high naphthalene conversion rate, high catalyst stability, and high selectivity of target products, and is more economical and efficient.

[0047] The following are specific examples.

[0048] Example 1 Cu / In2O3 & SAPO-11 was specifically prepared through the following process:

[0049] The Cu / In2O3 metal single-atom supported catalyst was prepared by mechanical ball milling: 0.0004 mol of copper nitrate, 0.03 mol of indium nitrate, and 0.03 mol of urea were put into an agate ball milling jar; 25 agate balls were added and sealed; ball milling was carried out on a planetary ball mill at a frequency of 50 Hz for 2 h; finally, it was calcined at 500 °C for 3 h to obtain the Cu / In2O3 metal single-atom supported catalyst. The mass percentage of metal copper in the metal single-atom supported catalyst is 0.3%.

[0050] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0051] Weigh 0.3 g of the above-mentioned Cu / In2O3 metal single-atom supported catalyst and 0.3 g of the SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed to obtain a mixed powder. Then, the above-mentioned mixed powder was put into a tablet press, and through tablet pressing and screening, a 20-40 mesh bifunctional catalyst, that is, Cu / In2O3 & SAPO-11 particles, was obtained.

[0052] Preparation of Example 2 Pd / In2O3 & SAPO-11

[0053] The Pd / In2O3 single-atom metal-loaded catalyst was prepared by the method of Example 1; the amount of palladium nitrate was 0.00025 mol, the amount of indium nitrate was 0.03 mol, and the amount of urea was 0.03 mol. The mass percentage of metallic palladium in the single-atom metal-loaded catalyst was 0.3%.

[0054] The SAPO-11 molecular sieve was a commercial molecular sieve.

[0055] 0.3 g of the above Pd / In2O3 single-atom metal-loaded catalyst and 0.3 g of the SAPO-11 molecular sieve were weighed and ground in an agate mortar for 30 minutes to mix them evenly. Then the above mixed powder was put into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a particle size of 20 - 40 mesh, namely Pd / In2O3&SAPO-11 particles, was obtained.

[0056] Preparation of Example 3 Rh / In2O3&SAPO-11

[0057] The Rh / In2O3 single-atom metal-loaded catalyst was prepared by the method of Example 1; the amount of rhodium nitrate was 0.00025 mol, the amount of indium nitrate was 0.03 mol, and the amount of urea was 0.03 mol. The mass percentage of metallic rhodium in the single-atom metal-loaded catalyst was 0.3%.

[0058] The SAPO-11 molecular sieve was a commercial molecular sieve.

[0059] 0.3 g of the above Rh / In2O3 single-atom metal-loaded catalyst and 0.3 g of the SAPO-11 molecular sieve were weighed and ground in an agate mortar for 30 minutes to mix them evenly. Then the above mixed powder was put into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a particle size of 20 - 40 mesh, namely Rh / In2O3&SAPO-11 particles, was obtained.

[0060] Preparation of Example 4 Pt / In2O3&SAPO-11

[0061] The Pt / In2O3 single-atom metal-loaded catalyst was prepared by the method of Example 1; the amount of platinum chloride was 0.00013 mol, the amount of indium nitrate was 0.03 mol, and the amount of urea was 0.03 mol. The mass percentage of metallic platinum in the single-atom metal-loaded catalyst was 0.3%.

[0062] The SAPO-11 molecular sieve was a commercial molecular sieve.

[0063] Weigh 0.3 g of the above-mentioned Pt / In2O3 single-atom metal-loaded catalyst and 0.3 g of SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, obtain a bifunctional catalyst with a mesh size of 20-40, namely Pt / In2O3&SAPO-11 particles.

[0064] Preparation of Example 5 Cu / In2O3&Zn-SAPO-11

[0065] The Cu / In2O3 single-atom metal-loaded catalyst is prepared by mechanical ball milling: put 0.0003 mol of copper nitrate, 0.03 mol of indium nitrate and 0.03 mol of urea into an agate ball milling jar; add 25 agate balls and seal; ball mill at a frequency of 50 Hz on a planetary ball mill for 2 h; finally calcine at 500 °C for 3 h to obtain the Cu / In2O3 single-atom metal-loaded catalyst. The mass percentage of metallic copper in the single-atom metal-loaded catalyst is 0.3%.

[0066] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0067] Immerse the SAPO-11 molecular sieve in a 0.0025 mol / L zinc nitrate solution, stir evenly with a glass rod, let it stand for 2 h, then put it into an 80 °C oven for 10 h, and then dry it and calcine it at 500 °C for 4 h to obtain Zn-SAPO-11; the loading amount of Zn is 3%.

[0068] Weigh 0.3 g of the above-mentioned Cu / In2O3 single-atom metal-loaded catalyst and 0.3 g of Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, obtain a bifunctional catalyst with a mesh size of 20-40, namely Cu / In2O3&Zn-SAPO-11 particles.

[0069] Preparation of Example 6 Cu / In2O3&La-HZSM-5

[0070] The preparation method of the Cu / In2O3 single-atom metal-loaded catalyst is the same as that in Example 5.

[0071] Preparation of the modified molecular sieve: Replace the zinc nitrate in Example 5 with lanthanum nitrate to obtain the modified molecular sieve, denoted as La-SAPO-11; the loading amount of La is 3%.

[0072] Weigh 0.3 g of the above-mentioned Cu / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of La-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above-mentioned mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40 is obtained, namely Cu / In₂O₃&La-HZSM-5 particles.

[0073] Example 7 Preparation of Cu / In₂O₃&Ga-SAPO-11

[0074] The preparation method of the Cu / In₂O₃ single-atom metal-loaded catalyst is the same as that in Example 5.

[0075] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 5 with gallium nitrate to obtain a modified molecular sieve, denoted as Ga-SAPO-11; the loading amount of Ga is 3%.

[0076] Weigh 0.3 g of the above-mentioned Cu / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above-mentioned mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40 is obtained, namely Cu / In₂O₃&Ga-SAPO-11 particles.

[0077] Example 8 Preparation of Cu / In₂O₃&Ce-SAPO-11

[0078] The preparation method of the Cu / In₂O₃ single-atom metal-loaded catalyst is the same as that in Example 5.

[0079] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 5 with cerium nitrate to obtain a modified molecular sieve, denoted as Ce-SAPO-11; the loading amount of Ce is 3%.

[0080] Weigh 0.3 g of the above-mentioned Cu / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above-mentioned mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40 is obtained, namely Cu / In₂O₃&Ce-SAPO-11 particles.

[0081] Example 9 Preparation of Pd / In₂O₃&Zn-SAPO-11

[0082] The Pd / In2O3 single-atom metal-loaded catalyst was prepared by mechanical ball milling: 0.006 mol of palladium nitrate, 0.03 mol of indium nitrate and 0.03 mol of urea were placed in an agate ball milling jar; 25 agate balls were added and sealed; ball milling was carried out on a planetary ball mill at a frequency of 50 Hz for 2 h; finally, it was calcined at 500 °C for 3 h to obtain the Pd / In2O3 single-atom metal-loaded catalyst.

[0083] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0084] The SAPO-11 molecular sieve was immersed in a 0.0025 mol / L zinc nitrate solution, stirred evenly with a glass rod, left standing for 2 h, then placed in an 80 °C oven for 10 h, and then dried and calcined at 500 °C for 4 h to obtain the modified molecular sieve, denoted as Zn-SAPO-11; the loading amount of Zn was 3%.

[0085] Weigh 0.3 g of the above Pd / In2O3 single-atom metal-loaded catalyst and 0.3 g of the Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40 was obtained, namely Pd / In2O3&Zn-SAPO-11 particles.

[0086] Preparation of Example 10 Pd / In2O3&La-HZSM-5

[0087] The preparation method of the Pd / In2O3 single-atom metal-loaded catalyst was the same as that in Example 9.

[0088] Preparation of the modified molecular sieve: Replace the zinc nitrate in Example 9 with lanthanum nitrate to obtain the modified molecular sieve, denoted as La-SAPO-11; the loading amount of La was 3%.

[0089] Weigh 0.3 g of the above Pd / In2O3 single-atom metal-loaded catalyst and 0.3 g of the La-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40 was obtained, namely Pd / In2O3&La-HZSM-5 particles.

[0090] Preparation of Example 11 Pd / In2O3&Ga-SAPO-11

[0091] The preparation method of the Pd / In2O3 single-atom metal-loaded catalyst was the same as that in Example 9.

[0092] Preparation of modified molecular sieve: Replace zinc nitrate in Example 9 with gallium nitrate to obtain a modified molecular sieve, denoted as Ga-SAPO-11; the loading amount of Ga is 3%.

[0093] Weigh 0.3 g of the above Pd / In2O3 single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, obtain a bifunctional catalyst with a particle size of 20-40 mesh, namely Pd / In2O3&Ga-SAPO-11 particles.

[0094] Preparation of Example 12 Pd / In2O3&Ce-SAPO-11

[0095] The preparation method of the Pd / In2O3 single-atom metal-loaded catalyst is the same as that in Example 9.

[0096] Preparation of modified molecular sieve: Replace zinc nitrate in Example 9 with cerium nitrate to obtain a modified molecular sieve, denoted as Ce-SAPO-11; the loading amount of Ce is 3%.

[0097] Weigh 0.3 g of the above Pd / In2O3 single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, obtain a bifunctional catalyst with a particle size of 20-40 mesh, namely Pd / In2O3&Ce-SAPO-11 particles.

[0098] Preparation of Example 13 Rh / In2O3&Zn-SAPO-11

[0099] The Rh / In2O3 single-atom metal-loaded catalyst is prepared by mechanical ball milling: Put 0.003 mol of nitric acid, 0.03 mol of indium nitrate and 0.03 mol of urea into an agate ball milling jar; add 25 agate balls and seal; ball mill at a frequency of 50 Hz on a planetary ball mill for 2 h; finally calcine at 500 °C for 3 h to obtain the Rh / In2O3 single-atom metal-loaded catalyst. The mass percentage content of metallic rhodium in the single-atom metal-loaded catalyst is 0.3%.

[0100] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0101] Immerse the SAPO-11 molecular sieve in a zinc nitrate solution, stir it evenly with a glass rod, let it stand for 2 h, then put it into an 80 °C oven for 10 h, and then dry it and calcine it at 500 °C for 4 h to obtain a modified molecular sieve, denoted as Zn-SAPO-11; the loading amount of Zn is 3%.

[0102] Weigh 0.3 g of the above-mentioned Rh / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40, namely Rh / In₂O₃&Zn-SAPO-11 particles, is obtained.

[0103] Preparation of Example 14 Rh / In₂O₃&La-HZSM-5

[0104] The preparation method of the Rh / In₂O₃ single-atom metal-loaded catalyst is the same as that in Example 13.

[0105] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 13 with lanthanum nitrate to obtain a modified molecular sieve, denoted as La-SAPO-11; the loading amount of La is 3%.

[0106] Weigh 0.3 g of the above-mentioned Rh / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of La-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40, namely Rh / In₂O₃&La-HZSM-5 particles, is obtained.

[0107] Preparation of Example 15 Rh / In₂O₃&Ga-SAPO-11

[0108] The preparation method of the Rh / In₂O₃ single-atom metal-loaded catalyst is the same as that in Example 13.

[0109] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 13 with gallium nitrate to obtain a modified molecular sieve, denoted as Ga-SAPO-11; the loading amount of Ga is 3%.

[0110] Weigh 0.3 g of the above-mentioned Rh / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20-40, namely Rh / In₂O₃&Ga-SAPO-11 particles, is obtained.

[0111] Preparation of Example 16 Rh / In₂O₃&Ce-SAPO-11

[0112] The preparation method of the Rh / In₂O₃ single-atom metal-loaded catalyst is the same as that in Example 13.

[0113] Preparation of modified molecular sieve: Replace zinc nitrate in Example 13 with cerium nitrate to obtain a modified molecular sieve, denoted as Ce-SAPO-11; the loading amount of Ce is 3%.

[0114] Weigh 0.3 g of the above-mentioned Rh / In2O3 single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with 20-40 mesh is obtained, namely Rh / In2O3&Ce-SAPO-11 particles.

[0115] Preparation of Example 17 Pt / In2O3&Zn-SAPO-11

[0116] The Pt / In2O3 single-atom metal-loaded catalyst is prepared by mechanical ball milling: Put 0.003 mol of platinum chloride, 0.03 mol of indium nitrate and 0.03 mol of urea into an agate ball milling jar; add 25 agate balls and seal; ball mill at a frequency of 50 Hz on a planetary ball mill for 2 h; finally calcine at 500 °C for 3 h to obtain the Pt / In2O3 single-atom metal-loaded catalyst. The mass percentage content of metallic platinum in the single-atom metal-loaded catalyst is 0.3%.

[0117] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0118] Immerse the SAPO-11 molecular sieve in a 0.0025 mol / L zinc nitrate solution, stir evenly with a glass rod, let it stand for 2 h, then put it into an 80 °C oven for 10 h, and then dry it and calcine it at 500 °C for 4 h to obtain a modified molecular sieve, denoted as Zn-SAPO-11; the loading amount of Zn is 3%.

[0119] Weigh 0.3 g of the above-mentioned Pt / In2O3 single-atom metal-loaded catalyst and 0.3 g of Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with 20-40 mesh is obtained, namely Pt / In2O3&Zn-SAPO-11 particles.

[0120] Preparation of Example 18 Pt / In2O3&La-HZSM-5

[0121] The preparation method of the Pt / In2O3 single-atom metal-loaded catalyst is the same as that in Example 17.

[0122] Preparation of modified molecular sieve: Replace zinc nitrate in Example 17 with lanthanum nitrate to obtain a modified molecular sieve, denoted as La-SAPO-11; the loading amount of La is 3%.

[0123] Weigh 0.3 g of the above-mentioned Pt / In2O3 single-atom metal-loaded catalyst and 0.3 g of La-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40, namely Pt / In2O3&La-HZSM-5 particles, is obtained.

[0124] Preparation of Example 19 Pt / In2O3&Ga-SAPO-11

[0125] The preparation method of the Pt / In2O3 single-atom metal-loaded catalyst is the same as that in Example 17.

[0126] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 17 with gallium nitrate to obtain a modified molecular sieve, denoted as Ga-SAPO-11; the loading amount of Ga is 3%.

[0127] Weigh 0.3 g of the above-mentioned Rh / In2O3 single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40, namely Pt / In2O3&Ga-SAPO-11 particles, is obtained.

[0128] Example 20 Pt / In2O 33 &Ce-SAPO-11 Preparation

[0129] The preparation method of the Pt / In2O3 single-atom metal-loaded catalyst is the same as that in Example 17.

[0130] Preparation of the modified molecular sieve: Replace zinc nitrate in Example 17 with cerium nitrate to obtain a modified molecular sieve, denoted as Ce-SAPO-11; the loading amount of Ce is 3%.

[0131] Weigh 0.3 g of the above-mentioned Pt / In2O3 single-atom metal-loaded catalyst and 0.3 g of Ga-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40, namely Pt / In2O3&Ce-SAPO-11 particles, is obtained.

[0132] Example 21 Cu / In2O3&SAPO-11 is specifically prepared through the following process:

[0133] The Cu / In2O3 metal single-atom supported catalyst is prepared by mechanical ball milling: 0.0003 mol of copper nitrate, 0.01 mol of indium nitrate and 0.01 mol of urea are placed in an agate ball milling jar; 25 agate balls are added and sealed; ball milling is carried out on a planetary ball mill at a frequency of 50 Hz for 0.5 h; finally, it is calcined at 400 °C for 4 h to obtain the Cu / In2O3 metal single-atom supported catalyst. The mass percentage of metallic copper in the metal single-atom supported catalyst is 0.7%.

[0134] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0135] The SAPO-11 molecular sieve is immersed in a 0.0001 mol / L zinc nitrate solution, stirred evenly with a glass rod, left standing for 2 h, then placed in an 80 °C oven for 10 h, and then dried and calcined at 600 °C for 3 h to obtain Zn-SAPO-11; the loading amount of Zn is 1%.

[0136] Weigh 0.3 g of the above-mentioned Cu / In2O3 metal single-atom supported catalyst and 0.7 g of the Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then the above-mentioned mixed powder is put into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a particle size of 20-40 mesh, namely Cu / In2O3&Zn-SAPO-11 particles, is obtained.

[0137] Example 22 Cu / In2O3&SAPO-11 is specifically prepared through the following process:

[0138] The Cu / In2O3 metal single-atom supported catalyst is prepared by mechanical ball milling: 0.0005 mol of copper nitrate, 0.1 mol of indium nitrate and 0.1 mol of urea are placed in an agate ball milling jar; 25 agate balls are added and sealed; ball milling is carried out on a planetary ball mill at a frequency of 50 Hz for 1 h; finally, it is calcined at 600 °C for 2 h to obtain the Cu / In2O3 metal single-atom supported catalyst. The mass percentage of metallic copper in the metal single-atom supported catalyst is 1%.

[0139] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0140] The SAPO-11 molecular sieve is immersed in a 0.0025 mol / L zinc nitrate solution, stirred evenly with a glass rod, left standing for 2 h, then placed in an 80 °C oven for 10 h, and then dried and calcined at 400 °C for 5 h to obtain Zn-SAPO-11; the loading amount of Zn is 3%.

[0141] Weigh 0.5 g of the above-mentioned Cu / In₂O₃ single-atom metal-loaded catalyst and 0.5 g of Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40, namely Cu / In₂O₃&Zn-SAPO-11 particles, is obtained.

[0142] Example 23 Cu / In₂O₃&SAPO-11 is specifically prepared through the following process:

[0143] The Cu / In₂O₃ single-atom metal-loaded catalyst is prepared by mechanical ball milling: put 0.00014 mol of copper nitrate, 0.03 mol of indium nitrate, and 0.03 mol of urea into an agate ball milling jar; add 25 agate balls and seal; ball mill at a frequency of 50 Hz on a planetary ball mill for 4 h; finally, calcine at 550 °C for 2 h to obtain the Cu / In₂O₃ single-atom metal-loaded catalyst. The mass percentage of metallic copper in the single-atom metal-loaded catalyst is 0.1%.

[0144] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0145] Immerse the SAPO-11 molecular sieve in a 0.0025 mol / L zinc nitrate solution, stir evenly with a glass rod, let it stand for 2 h, then put it into an 80 °C oven for 10 h, and then dry it and calcine it at 450 °C for 4 h to obtain Zn-SAPO-11; the loading amount of Zn is 3%.

[0146] Weigh 0.7 g of the above-mentioned Cu / In₂O₃ single-atom metal-loaded catalyst and 0.3 g of Zn-SAPO-11 molecular sieve, and grind them in an agate mortar for 30 minutes to make them evenly mixed. Then put the above mixed powder into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a mesh size of 20 - 40, namely Cu / In₂O₃&Zn-SAPO-11 particles, is obtained.

[0147] Example 24 Cu / In₂O₃&SAPO-11 is specifically prepared through the following process:

[0148] The Cu / In₂O₃ single-atom metal-loaded catalyst is prepared by mechanical ball milling: put 0.0014 mol of copper nitrate, 0.03 mol of indium nitrate, and 0.03 mol of urea into an agate ball milling jar; add 25 agate balls and seal; ball mill at a frequency of 50 Hz on a planetary ball mill for 4 h; finally, calcine at 550 °C for 2 h to obtain the Cu / In₂O₃ single-atom metal-loaded catalyst. The mass percentage of metallic copper in the single-atom metal-loaded catalyst is 1%.

[0149] The SAPO-11 molecular sieve is a commercial molecular sieve.

[0150] The SAPO-11 molecular sieve was immersed in a 0.0025 mol / L zinc nitrate solution. After being evenly stirred with a glass rod, it was left standing for 2 h and then placed in an oven at 80 °C for 10 h. Then, after drying, it was calcined at 500 °C for 4 h to obtain Zn-SAPO-11; the loading amount of Zn was 3%.

[0151] 0.7 g of the above-mentioned Cu / In2O3 single-atom metal-loaded catalyst and 0.3 g of the Zn-SAPO-11 molecular sieve were weighed and ground in an agate mortar for 30 minutes to make them evenly mixed. Then, the above-mentioned mixed powder was put into a tablet press, and through tablet pressing and screening, a bifunctional catalyst with a particle size of 20-40 mesh, namely Cu / In2O3&Zn-SAPO-11 particles, was obtained.

[0152] The catalytic performance test for the one-step synthesis of 2-methylnaphthalene / 2,6-dimethylnaphthalene from syngas and naphthalene using the catalyst is as follows:

[0153] 0.1 g of the "single-atom metal - molecular sieve" bifunctional catalyst was loaded for testing the catalytic performance. The reaction temperature was 380 °C and the pressure was 3 MPa. The feed gas was composed of CO and H2 (volume ratio H2 / CO = 2), and the space velocity (GHSV) was 9000 mL / (g cat ·h); naphthalene was dissolved in mesitylene and pumped into the fixed bed by a peristaltic pump under pressure. The liquid hourly space velocity of naphthalene was 0.5 h -1 .

[0154] 1. The catalysts in the above Examples 1 - 4 were subjected to performance testing:

[0155] Evaluation conditions: 380 °C, 3 MPa;

[0156] Table 1 Results of the evaluation reaction at 380 °C and 3 MPa

[0157]

[0158]

[0159] 2. The catalysts in the above Examples 5 - 8 were subjected to performance testing;

[0160] Evaluation conditions: 380 °C, 3 MPa;

[0161] Table 2 Results of the evaluation reaction of the catalyst at 380 °C and 3 MPa

[0162]

[0163] 3. The catalysts in the above Examples 9 - 12 were subjected to performance testing;

[0164] Evaluation conditions: 380°C, 3 MPa;

[0165] Table 3 Results of the evaluation reaction of the catalyst at 380°C, 3 MPa

[0166]

[0167]

[0168] 4. Perform performance tests on the catalysts in Examples 13 - 16 above;

[0169] Evaluation conditions: 380°C, 3 MPa;

[0170] Table 4 Results of the evaluation reaction of the catalyst at 380°C, 3 MPa

[0171]

[0172] 5. Perform performance tests on the catalysts in Examples 17 - 20 above;

[0173] Evaluation conditions: 380°C, 3 MPa;

[0174] Table 5 Results of the evaluation reaction of the catalyst at 380°C, 3 MPa

[0175]

[0176]

[0177] Through the comparison of Tables 1, 2, 3, 4 and 5, it can be seen that the noble metal-loaded catalyst composite SAPO-11 molecular sieve has better catalyst stability than the non-noble metal-loaded catalyst composite SAPO-11 molecular sieve, and is superior to the non-noble metal-loaded catalyst in terms of the conversion rate of naphthalene, the selectivity of 2-methylnaphthalene, and the selectivity of 2,6-dimethylnaphthalene. The results show that the Pd / In2O3&SAPO-11 bifunctional catalyst has the best catalytic performance, and the catalyst life is up to 450 h at most. Compared with SAPO-11, the SAPO-11 zeolite molecular sieve modified by Zn and Ga is superior to the parent SAPO-11 molecular sieve in terms of the conversion rate of naphthalene, the selectivity of 2-methylnaphthalene, and the selectivity of 2,6-dimethylnaphthalene. The results show that the Ga-modified molecular sieve has the best performance, with the naphthalene conversion rate increased from 51% to 55%, the selectivity of 2-methylnaphthalene increased from 39% to 57%, and the selectivity of 2,6-dimethylnaphthalene increased from 17% to 20%. In the Pd / In2O3 single metal atom-loaded catalyst, the isolated metal and the support both serve as active sites for H2 dissociation, thereby increasing the local concentration of active H* species and greatly improving the yield of methanol intermediates. And the single metal atom-loaded catalyst has a strong interaction between the metal active center and the support, and it is not easy to cause the loss of active components. At the same time, the modified Ga-SAPO-11 molecular sieve reduces the total acid amount, and the appropriate L acid (Lewis acid) is beneficial to the desorption of naphthalene and the target product, thereby improving the naphthalene conversion efficiency and increasing the selectivity of the target product. Compared with the parent SAPO-11 molecular sieve, the introduction of heteroatom metals forms medium-strength B acid, which improves the desorption of the target product while enhancing the conversion of naphthalene.

[0178] Compared with Patent CN112657538A, when the synthesis gas is used as the raw material in the present invention, the conversion rate of naphthalene is ensured while the life is greatly improved, from about 100 h originally to 300 - 500 h.

[0179] Compared with Patent CN118950074A, carbon dioxide is difficult to activate, so it is not conducive to the conversion rate of naphthalene, but the catalyst life is longer. The bifunctional catalyst proposed in the present invention improves the conversion rate of naphthalene and the selectivity of 2,6-dimethylnaphthalene while ensuring the catalyst life.

[0180] In the present invention, Pd / In2O3&Ga-SAPO-11 obtained by combining Pd / In2O3 prepared by mechanical ball milling method with modified Ga-SAPO-11 exhibits excellent stability, naphthalene conversion rate, and selectivity of 2-methylnaphthalene and 2,6-dimethylnaphthalene in the synthesis gas route.

[0181] In the metal single-atom supported catalyst prepared in the present invention, both the isolated metal and the support are used as active sites for H2 dissociation, thereby increasing the local concentration of active H* species and greatly improving the yield of methanol intermediates. Moreover, the metal single-atom supported catalyst has a strong interaction between the metal active center and the support, and it is not easy for the active components to be lost. Specifically, in the present invention, the metal is incorporated into the lattice of indium oxide in the form of single atoms. This structure has a strong interaction between the metal active center and the support, and it is not easy for the active components to be lost, greatly improving the stability of the catalyst. At the same time, the incorporation of heteroatoms increases the concentration of oxygen vacancies on the surface of indium oxide, enhancing the adsorption and activation ability of CO. At the same time, the interface between the metal single atoms and indium oxide has strong H2 dissociation active sites, increasing the local concentration of active H* species, promoting the transformation of CO species into HCOO* species and OCH3* species, and greatly increasing the concentration of methyl intermediates. Cooperating with a molecular sieve with milder acidity (with a weaker acid strength) can enhance the conversion of naphthalene; at the same time, it inhibits the deep alkylation reaction of the products, effectively improving the selectivity of methylnaphthalene. At the same time, the modified molecular sieve has a more reasonable acid site distribution, which is beneficial to improving the selectivity of 2-methylnaphthalene / 2,6-dimethylnaphthalene.

[0182] The modified Ga-SAPO-11 molecular sieve of the present invention reduces the total acid amount. Appropriate L acid is beneficial to the desorption of naphthalene and the desorption of the target product, thereby improving the naphthalene conversion efficiency and increasing the selectivity of the target product. Compared with the parent SAPO-11 molecular sieve, introducing heteroatom metal medium-strength B acid can improve the desorption of the target product while enhancing the naphthalene conversion. At the same time, the milder acid sites are not prone to coking side reactions, increasing the catalyst stability from 450 h to 500 h.

[0183] The above is only an illustration of the best embodiment of the present invention, but it should not be construed as a limitation of the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to change. Any changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0184] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

Claims

1. A bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene, characterized in that: Including metal single atom supported catalysts and molecular sieves; The metal single atom supported catalyst includes In2O3 and one metal among Cu, Pd, Rh and Pt supported on In2O3.

2. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 1, characterized in that: The mass ratio of the molecular sieve to the metal single atom supported catalyst is 3:7 to 7:

3.

3. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 1, characterized in that: The mass percentage of the single-atom metal loading in the metal single-atom loaded catalyst is 0.1% to 1%.

4. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 1, characterized in that: Metal single atom supported catalysts are prepared by the following process: One of copper nitrate, palladium nitrate, rhodium nitrate and platinum chloride is ball-milled with indium nitrate and urea and then calcined to obtain a metal single-atom supported catalyst.

5. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 4, characterized in that: Ball milling was performed at 50 Hz for 0.5-4 h; The molar ratio of copper nitrate, palladium nitrate, rhodium nitrate, one of platinum chloride, indium nitrate and urea is (0.00001-0.0005):(0.01-0.1):(0.01-0.1); The calcination temperature is 400-600°C and the calcination time is 4-6h.

6. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 1, characterized in that: The molecular sieve is SAPO-11 molecular sieve, or the molecular sieve is prepared by the following process: immersing the SAPO-11 molecular sieve in zinc nitrate, gallium nitrate, cerium nitrate or lanthanum nitrate solution, drying after standing, and calcining to obtain the modified molecular sieve.

7. The bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to claim 6, characterized in that: The loading amount of zinc, gallium, cerium or lanthanum is 1%-3% of the molecular sieve mass; The calcination temperature is 400-600°C and the time is 3-5h.

8. A method for preparing a bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas and naphthalene according to any one of claims 1 to 7, characterized in that: The following steps are involved: The metal single atom supported catalyst is mixed with the molecular sieve and pressed into tablets to obtain a bifunctional catalyst for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene by alkylation of synthesis gas with naphthalene.

9. Use of the bifunctional catalyst as claimed in any one of claims 1 to 7 in the one-step process for preparing 2-methylnaphthalene or 2,6-dimethylnaphthalene from synthesis gas and naphthalene.

10. A use according to claim 9, characterized in that The catalyst is added to a fixed bed reactor, and then synthesis gas and naphthalene are introduced to react at a pressure of 1 to 5 MPa and 300 to 550°C to generate 2-methylnaphthalene or 2,6-dimethylnaphthalene; the volume ratio of carbon monoxide to hydrogen in the synthesis gas is (0.1 to 8): 1, and the volume space velocity of the synthesis gas is 1000 to 50000 h -1 ; The mass space velocity of naphthalene is 0.1~5h -1 .

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