Catalyst and preparation method thereof, and method for preparing aromatic hydrocarbon based on catalyst

Abstract

The invention provides a catalyst, a preparation method thereof and a method for preparing aromatic hydrocarbon based on the catalyst, and relates to the technical field of catalysts.The catalyst comprises a molecular sieve shell and a metal particle core located in the molecular sieve shell, and the metal particle core is composed of a plurality of discrete metal nanoparticles; the metal nanoparticles are isolated by the molecular sieve matrix; an annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the dynamic diameter of aromatic hydrocarbon; the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100. According to the application, the metal nanoparticles are encapsulated in the molecular sieve shell, and the annular gap is formed between the metal particle core and the molecular sieve shell, so that high selectivity and high conversion rate of aromatic hydrocarbon products are realized, and catalyst deactivation caused by carbon deposition formed in the catalyst due to difficulty in diffusion of macromolecular products is avoided.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of catalysts. Specifically, the embodiments relate to a catalyst, a preparation method thereof, and a method for preparing aromatic hydrocarbons based on the catalyst. Background Art

[0002] Aromatic hydrocarbons are important chemical raw materials and can be used to prepare a variety of chemical fibers, engineering plastics, and pharmaceutical intermediates. The market is vast and the consumption is large. Traditional aromatic hydrocarbon preparation technologies are obtained from naphtha reforming or by-products of ethylene cracking units. Recently, the preparation of aromatic hydrocarbons from methanol or the preparation of olefins from syngas provides a variety of alternative raw materials such as alcohols and olefins, which is a new choice for countries and regions with a large amount of imported oil.

[0003] Catalysts for preparing aromatic hydrocarbons are often metal-molecular sieve bifunctional catalysts. Enclosing the metal within the molecular sieve pores can effectively improve the performance and lifespan of the propane dehydrogenation catalyst. However, the aromatization reaction generates molecules of benzene, toluene, xylene, trimethylbenzene, or larger aromatic hydrocarbons. If the encapsulated metal blocks the pores of the molecular sieve, it is not conducive to the diffusion of these large molecules, but instead will exacerbate the catalyst deactivation due to carbon deposition. Therefore, how to avoid catalyst deactivation caused by carbon deposition and improve the catalyst lifespan has become an urgent problem to be solved in the field. Summary of the Invention

[0004] The embodiments of the present application aim to provide a catalyst, a preparation method thereof, and a method for preparing aromatic hydrocarbons based on the catalyst, aiming to solve the problem of how to avoid catalyst deactivation caused by carbon deposition and improve the catalyst lifespan.

[0005] In a first aspect of the embodiments of the present application, a catalyst is provided. The catalyst is configured to convert olefins or alcohols into aromatic hydrocarbons under a high hydrogen partial pressure. The catalyst includes a core-shell structure, and the core-shell structure includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell. The metal particle core is composed of multiple discrete metal nanoparticles, and each metal nanoparticle is isolated by a molecular sieve matrix;

[0006] An annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the kinetic diameter of the aromatic hydrocarbon; the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100.

[0007] In an optional embodiment, the minimum distance of the annular gap between the molecular sieve shell and the metal particle core is greater than or equal to 0.4 nm and less than or equal to 1 nm.

[0008] In an optional embodiment, the average diameter of the metal particle nuclei is greater than or equal to 1 nm and less than or equal to 5 nm.

[0009] In an optional embodiment, the molecular sieve shell includes at least one of the following: ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-22 molecular sieve, Y molecular sieve, MCM-22 molecular sieve, MCM-41 molecular sieve.

[0010] In an optional embodiment, the metal nanoparticles include at least one of the following: zinc, iron, manganese, silver, molybdenum, nickel, chromium, copper.

[0011] The second aspect of the embodiments of the present application provides a method for preparing a catalyst for preparing the catalyst according to any one of the first aspects of the embodiments of the present application. The preparation method includes:

[0012] Based on the first raw material, metal nanoparticles in an oxidized state are prepared;

[0013] Based on the hydrocarbon cracking method, the metal nanoparticles in the oxidized state are treated so that a carbon layer is coated on the surface of the metal nanoparticles, and the thickness of the carbon layer is greater than or equal to 0.4 nm and less than or equal to 1 nm;

[0014] Based on the second raw material, the metal nanoparticles coated with a carbon layer are hydrothermally treated to obtain a first product. The first product includes a molecular sieve shell and metal particle nuclei located inside the molecular sieve shell. The metal particle nuclei include a plurality of metal nanoparticles coated with a carbon layer, and each metal nanoparticle is isolated by a molecular sieve matrix;

[0015] The first product is calcined to remove the carbon layer on the surface of the metal nanoparticles to obtain the catalyst.

[0016] In an optional embodiment, the first raw material includes at least one of the following: nitrates, chlorides, and organometallic compounds corresponding to the metal nanoparticles.

[0017] In an optional embodiment, the second raw material is used to form the molecular sieve shell. The second raw material includes a silicon source, an aluminum source, and a template agent. Among them, the silicon source includes at least one of the following: silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, sodium silicate;

[0018] The aluminum source includes at least one of the following: sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, aluminum nitrate, alumina, aluminum chloride;

[0019] The template agent includes at least one of the following: tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, hexamethyleneimine, cetyltrimethylammonium bromide, diethylamine, triethylamine, 1,6-hexanediamine.

[0020] In the third aspect of the embodiments of the present application, a method for preparing aromatics based on a catalyst is provided. The catalyst is the catalyst as described in any one of the first aspect of the embodiments of the present application. The method includes:

[0021] Adding the catalyst into a reactor and heating the reactor to a preset temperature;

[0022] Adding a reaction raw material into the reactor, controlling the catalyst to be at a preset mass space velocity, and converting the reaction raw material under a preset pressure, so that the reaction raw material undergoes an aromatization reaction in a hydrogen atmosphere to obtain an aromatic hydrocarbon product. The reaction raw material includes a raw material gas containing olefins or alcohols, and the hydrogen partial pressure of the raw material gas is 10%-50%;

[0023] Wherein, the preset temperature is 450°C - 600°C; the preset mass space velocity is 0.2h -1 -5h -1 ; the preset pressure is 0.1MPa - 3MPa; the conversion time is 1 - 10h.

[0024] In an optional embodiment, after obtaining the aromatic hydrocarbon product, the method further includes:

[0025] When the activity of the catalyst drops to the target conversion rate, transferring the catalyst into an oxygen-containing atmosphere for carbon burning treatment to remove the carbon deposited on the surface of the catalyst, and obtaining a regenerated catalyst;

[0026] Adding the regenerated catalyst into the reactor and converting the reaction raw material based on the regenerated catalyst to obtain the aromatic hydrocarbon product.

[0027] Beneficial effects:

[0028] The present application provides a catalyst, a preparation method thereof, and a method for preparing aromatic hydrocarbons based on the catalyst. The catalyst is configured to convert olefins or alcohols into aromatic hydrocarbons under a high hydrogen partial pressure. The catalyst includes a core-shell structure, which includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell. The metal particle core is composed of multiple discrete metal nanoparticles, and the metal nanoparticles are isolated from each other by a molecular sieve matrix; an annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the kinetic diameter of the aromatic hydrocarbon; the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100. By encapsulating metal nanoparticles inside the molecular sieve shell, during the process of converting reactants into aromatic hydrocarbons based on the catalyst, the reactants first contact the molecular sieve shell compared to the metal nanoparticles, thereby achieving high selectivity and high conversion rate of the aromatic hydrocarbon product; by setting an annular gap between the metal particle core and the molecular sieve shell, a diffusion path is provided for the macromolecular products generated at the reaction sites on the surface of the metal particle core to diffuse to the outside of the molecular sieve shell, thereby avoiding catalyst deactivation caused by carbon deposition formed inside the catalyst due to the difficulty of macromolecular products to diffuse, and effectively improving the catalyst life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 is a schematic flow chart of a method for preparing a catalyst proposed in an embodiment of the present application;

[0031] Figure 2 is a schematic flow chart of a method for preparing aromatic hydrocarbons based on a catalyst proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the protection scope of the present application.

[0033] In the drawings, for clarity sometimes, the sizes of the constituent elements, the thicknesses of layers or regions may be exaggerated. Therefore, any implementation of the present disclosure is not necessarily limited to the dimensions shown in the figures, and the shapes and sizes of the components in the drawings do not reflect the true scale. In addition, the drawings schematically show ideal examples, and any implementation of the present disclosure is not limited to the shapes or values shown in the drawings, etc.

[0034] Aromatics are an important chemical raw material and can be used to prepare a variety of chemical fibers, engineering plastics and pharmaceutical intermediates. The market is vast and the consumption is large. Traditional aromatic preparation technologies are obtained from naphtha reforming or by-products of ethylene cracking units. Recently, the preparation of aromatics from methanol or the preparation of olefins from syngas provides a variety of alternative raw materials such as alcohols and olefins, which is a new choice for countries and regions with a large amount of imported oil.

[0035] In many cases, the alcohol conversion or the crude olefin products contain a large amount of hydrogen. For example, when preparing olefins from syngas, the reactor outlet products include unreacted syngas (CO and H2), CO2, water and a mixture of olefins and light alkanes. When alcohol is converted, a mixture of light olefins, alkanes, hydrogen, aromatics and water is also generated. Since the temperatures of these two reactions are very high, if it can be directly converted into aromatics without cooling and separation, it has the advantages of short process and good energy-saving effect. However, the catalyst for preparing aromatics is often a bifunctional catalyst of metal-molecular sieve. The hydrogenation reaction rate of olefins and hydrogen on the metal is much faster than the aromatization reaction rate of olefins or alcohols diffusing into the interior of the molecular sieve (the hydrocarbon pool mechanism in the pores). The existence of this competitive reaction greatly increases the probability of olefin hydrogenation to form inert alkanes and increases the difficulty of the aromatization reaction.

[0036] From the perspective of the loading relationship between the molecular sieve and the metal, there are currently three different metal loading types: the form of preferentially loading the metal on the surface of the molecular sieve (mostly using noble metals to reduce their usage), the metal being uniformly dispersed in the bulk phase of the molecular sieve, and the metal being encapsulated in the pores of the molecular sieve. Exemplarily, encapsulating Pt, In, Ir, etc. inside the molecular sieve can avoid further sintering of the metal and improve the stability at high temperatures, thereby effectively improving the catalyst performance and life of propane dehydrogenation. However, the aromatization reaction generates molecules such as benzene, toluene, xylene, trimethylbenzene or larger aromatics. If the encapsulated metal blocks the pores of the molecular sieve, it is not conducive to the diffusion of these macromolecules, but will instead exacerbate the catalyst carbon deposition deactivation. Therefore, the effective design of olefin and alcohol aromatization catalysts under high hydrogen partial pressure is always a major challenge.

[0037] In view of this, an embodiment of the present application provides a catalyst configured to convert olefins or alcohols into aromatics under a high hydrogen partial pressure. The catalyst includes a core-shell structure, which includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell. The metal particle core is composed of a plurality of discrete metal nanoparticles, and the metal nanoparticles are configured to provide catalytic sites for the aromatization reaction of reaction raw materials (olefins or alcohols) and hydrogen.

[0038] Since the contact probability of hydrogen with the catalytic sites on the metal nanoparticles is much higher than the probability of olefins diffusing into the molecular sieve pores, and the activation energy of the hydrogenation reaction is usually lower than that of the aromatization reaction, when the reaction raw materials are in direct contact with the metal nanoparticles, alkanes are more likely to be generated thermodynamically, resulting in a decrease in the probability of the aromatization reaction. Therefore, in the embodiment of the present application, by encapsulating the metal particle core inside the molecular sieve shell, the reaction raw materials need to pass through the molecular sieve pores before contacting the metal particle core. The molecular sieve pores can physically block the direct contact of part of H2 with olefins at the metal sites, which is beneficial to isolating part of H2 and reducing the H2 diffusion rate. External olefins need to diffuse into the molecular sieve pores to contact the metal particle core encapsulated inside the molecular sieve shell, and aromatization steps such as cyclization and hydrogen transfer are realized through the hydrocarbon pool mechanism in the molecular sieve pores, making the aromatization reaction have a stronger dominant position compared with the hydrogenation reaction on the catalytic sites on the surface of the metal particle core, thus effectively inhibiting the hydrogenation competition and reducing the probability of the reaction raw materials generating alkanes at the catalytic sites of the metal particle core, and improving the aromatization efficiency.

[0039] In the embodiment of the present application, by arranging the metal particle core inside the molecular sieve shell, the probability of the aromatization reaction can be increased by 50%-80%, and the selectivity of inert alkanes can be decreased by 50%-80%.

[0040] In some optional embodiments, the nanoparticle core includes a plurality of metal nanoparticles, and the metal nanoparticles are separated by a molecular sieve matrix. The rigid pore or shell structure of the molecular sieve matrix restricts the movement of the metal nanoparticles and prevents them from contacting each other to avoid agglomeration between the plurality of metal nanoparticles, ensuring the number of active catalytic sites in the catalyst and preventing the catalytic performance from decreasing.

[0041] In the embodiments of the present application, in order to enable the aromatic products generated on the surface of the metal particle core to diffuse to the outside of the molecular sieve shell, and to prevent the aromatic hydrocarbons or other macromolecular products from failing to diffuse to the outside of the molecular sieve shell in time, resulting in carbonization and accumulation on the surface of the metal particle core and in the pores of the molecular sieve, causing the catalyst to deactivate, an annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the kinetic diameter of the aromatic hydrocarbon.

[0042] In some optional embodiments, the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100. By restricting the relative sizes of the average diameters of the metal particle core and the molecular sieve shell in the embodiments of the present application, the metal particle core will not have problems such as being unable to be encapsulated inside the molecular sieve shell due to its size being too small relative to the molecular sieve shell (such as the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core being less than 10), and the number of surface reaction sites of the metal particle core being too small, effectively ensuring the aromatization efficiency. At the same time, the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core being less than or equal to 100 ensures that the metal particle core will not be too large relative to the molecular sieve shell, resulting in the spacing of the annular gap between the metal particle core and the molecular sieve shell being such that aromatic products can pass through, ensuring the activity of the catalyst.

[0043] In the embodiments of the present application, since the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100, while ensuring the catalytic activity of the catalyst for the aromatization reaction, the mechanical strength of the catalyst can be effectively improved, preventing the catalyst from pulverizing and losing its catalytic ability during the preparation of aromatic hydrocarbons. Among them, compared with hollow molecular sieves encapsulating a small amount of small-sized metals, the pulverization rate of the catalyst with the ratio of the average diameters of the molecular sieve shell and the metal particle core provided in the embodiments of the present application is reduced by 50%-80%.

[0044] In some optional embodiments, the minimum distance of the annular gap between the molecular sieve shell and the metal particle core is greater than or equal to 0.4 nm and less than or equal to 1 nm.

[0045] In some optional embodiments, the average diameter of the metal particle core is greater than or equal to 1 nm and less than or equal to 5 nm.

[0046] In some optional embodiments, the molecular sieve shell includes at least one of the following: ZSM-5 type molecular sieve, ZSM-11 type molecular sieve, ZSM-22 type molecular sieve, Y type molecular sieve, MCM-22 type molecular sieve, MCM-41 type molecular sieve.

[0047] In some optional embodiments, the metal nanoparticles include at least one of the following: zinc, iron, manganese, silver, molybdenum, nickel, chromium, and copper.

[0048] This application provides a catalyst, a preparation method thereof, and a method for preparing aromatic hydrocarbons based on the catalyst. The catalyst is configured to convert olefins or alcohols into aromatic hydrocarbons under a high hydrogen partial pressure. The catalyst includes a core-shell structure, which includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell. The metal particle core is composed of multiple discrete metal nanoparticles, and the metal nanoparticles are isolated by a molecular sieve matrix; an annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the kinetic diameter of the aromatic hydrocarbon; the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100. In this application, by encapsulating the metal nanoparticles inside the molecular sieve shell, when the reactants are converted into aromatic hydrocarbons based on the catalyst, the reactants first contact the molecular sieve shell compared to the metal nanoparticles, thereby achieving high selectivity and high conversion rate of the aromatic hydrocarbon products; in this application, by setting an annular gap between the metal particle core and the molecular sieve shell, a diffusion path is provided for the macromolecular products generated at the reaction sites on the surface of the metal particle core to diffuse to the outside of the molecular sieve shell, thereby avoiding catalyst deactivation caused by coke deposition on the metal particle surface due to the difficulty of macromolecular products to diffuse, and effectively improving the catalyst life.

[0049] Based on the same inventive concept, an embodiment of this application discloses a preparation method of a catalyst. The preparation method is used to prepare the catalyst proposed in the embodiment of this application. Figure 1 The flowchart of a preparation method of a catalyst proposed in an embodiment of this application is shown. As Figure 1 shown, the preparation method includes the following steps:

[0050] S101. Prepare metal nanoparticles in an oxidized state based on a first raw material.

[0051] When specifically implementing step S101, based on the first raw material, the metal nanoparticles in an oxidized state are prepared by a co-precipitation method, a metal organic compound decomposition method, or a Sol-gel method. Among them, the average diameter of the metal nanoparticles is greater than or equal to 1 nm and less than or equal to 5 nm.

[0052] In some optional embodiments, the first raw material includes at least one of the following: nitrates, chlorides, and organometallic compounds corresponding to the metal nanoparticles.

[0053] S102. Treat the metal nanoparticles in the oxidized state based on hydrocarbon cracking to coat the surface of the metal nanoparticles with a carbon layer.

[0054] When specifically implementing step S102, within a first preset temperature range, treat the metal nanoparticles in the oxidized state based on hydrocarbon cracking to coat the surface of the metal nanoparticles with a carbon layer. The thickness of the carbon layer is greater than or equal to 0.4 nm and less than or equal to 1 nm. The carbon layer is used to protect the metal nanoparticles from losing catalytic activity during subsequent hydrothermal processes and to form an annular gap between the molecular sieve shell and the metal particle core in the catalyst.

[0055] In the embodiments of the present application, during the preparation of the catalyst, a carbon layer is formed outside the metal particle core before forming the molecular sieve shell to temporarily occupy the space outside the metal particle core. The thickness of the carbon layer is kept consistent with the minimum distance of the annular gap. After forming the molecular sieve shell, the carbon layer coating the metal particle core is removed, thereby releasing the space occupied by the carbon layer and forming the annular gap between the molecular sieve shell and the metal particle core in the catalyst. Through the annular gap, a diffusion path for the aromatic hydrocarbon product to diffuse outside the molecular sieve shell is provided.

[0056] Optionally, the raw material of the hydrocarbon cracking method includes hydrocarbons with C2 - C6, and the first preset temperature range of the hydrocarbon cracking method is 250°C - 500°C.

[0057] S103. Perform hydrothermal treatment on the metal nanoparticles coated with a carbon layer based on a second raw material to obtain a first product. The first product includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell. The metal particle core includes multiple metal nanoparticles coated with a carbon layer on the surface, and each metal nanoparticle is isolated by a molecular sieve matrix.

[0058] When specifically implementing step S103, the second raw material is used to form the molecular sieve shell. The second raw material includes a silicon source, an aluminum source, and a template agent. Specifically, place the metal nanoparticles coated with a carbon layer in the silicon source, add the aluminum source and the template agent, and perform hydrothermal treatment for a first preset duration in a sealed environment within a second preset temperature range to form the molecular sieve shell outside the metal nanoparticles coated with a carbon layer and obtain the first product.

[0059] In the embodiments of the present application, since the metal nanoparticles are coated with the carbon layer during hydrothermal treatment of the metal nanoparticles, the carbon layer can protect the metal nanoparticles from oxidation dissolution or migration aggregation, ensuring the catalytic performance of the metal nanoparticles.

[0060] Optionally, the second preset temperature range is 150 - 230 °C, and the first preset duration is 3 - 48 h.

[0061] In some optional embodiments, the silicon source includes at least one of the following: silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, sodium silicate; the aluminum source includes at least one of the following: sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, aluminum nitrate, alumina, aluminum chloride; the template agent includes at least one of the following: tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, hexamethyleneimine, cetyltrimethylammonium bromide, diethylamine, triethylamine, 1,6 - hexanediamine.

[0062] S104. Calcinate the first product to remove the carbon layer on the surface of the metal nanoparticles, thereby obtaining the catalyst.

[0063] In the specific implementation step S104, after obtaining the first product, filter out the first product and dry it for a second preset duration within a third preset temperature range. At this time, the molecular sieve shell and the metal nanoparticles are separated by the carbon layer coating the metal nanoparticles. In order to form an annular gap between the metal particle core and the molecular sieve shell in the catalyst, calcinate the first product in an air atmosphere within a fourth preset temperature range for a third preset duration to obtain the catalyst. The catalyst includes a molecular sieve shell and a metal particle core encapsulated inside the molecular sieve shell, and there is an annular gap between the metal particle core and the molecular sieve shell.

[0064] Optionally, the third preset temperature range is 100 °C - 120 °C, and the second preset duration is 3 h - 10 h; the fourth preset temperature range is 400 °C - 600 °C, and the third preset duration is 3 h - 10 h.

[0065] Based on the same inventive concept, an embodiment of the present application discloses a method for preparing aromatic hydrocarbons based on a catalyst, and the catalyst is the catalyst mentioned in the embodiments of the present application. Figure 2 The flowchart of a method for preparing aromatic hydrocarbons based on a catalyst proposed in an embodiment of the present application is shown. As Figure 2 shown, the method includes the following steps:

[0066] S201. Add the catalyst to a reactor and heat the reactor to a preset temperature.

[0067] S202. Add the reaction raw materials into the reactor, control the catalyst at a preset mass space velocity, and convert the reaction raw materials under a preset pressure so that the reaction raw materials undergo an aromatization reaction in a hydrogen atmosphere to obtain an aromatic hydrocarbon product. The reaction raw materials include a raw material gas containing olefins or alcohols, and the hydrogen partial pressure of the raw material gas is 10%-50%.

[0068] Among them, the preset temperature is 450°C - 600°C; the preset mass space velocity is 0.2 h -1 -5 h -1 ; the preset pressure is 0.1 MPa - 3 MPa; the conversion time is 1 - 10 h.

[0069] In some optional embodiments, after obtaining the aromatic hydrocarbon product, since some of the formed macromolecular products will be converted into carbon and accumulate on the surface of the metal nanoparticles, the carbon deposition will cover some reaction sites and cause the activity and lifespan of the catalyst to decline. Therefore, the catalyst can be regenerated to remove the carbon deposition on the surface of the catalyst. Specifically, after obtaining the aromatic hydrocarbon product, the method further includes: when the activity of the catalyst drops to the target conversion rate, transferring the catalyst to an oxygen-containing atmosphere for carbon burning treatment to remove the carbon deposition on the surface of the catalyst and obtain a regenerated catalyst. Optionally, the temperature range of the carbon burning treatment is 500°C - 700°C; adding the regenerated catalyst into the reactor and converting the reaction raw materials based on the regenerated catalyst to obtain the aromatic hydrocarbon product.

[0070] In the embodiments of the present application, in the aromatic hydrocarbon product prepared based on the catalyst obtained by the above method, the hydrocarbon group selectivity from olefins to aromatic hydrocarbons is greater than or equal to 65%.

[0071] In order to enable those skilled in the art to better understand the preparation method of the catalyst provided by the present application and the method for preparing aromatic hydrocarbons based on the catalyst, the following specific embodiments will be used to introduce in detail the preparation method of the catalyst provided by the present application and the method for preparing aromatic hydrocarbons based on the catalyst. It should be noted that the following embodiments are only some specific embodiments given to better illustrate the solution of the present application, and the specific parameters and substances in the preparation method of the catalyst and the method for preparing aromatic hydrocarbons based on the catalyst are not limited to the situations listed in the following embodiments.

[0072] Example 1

[0073] Prepare the oxidized state of metal nanoparticles (zinc, iron, manganese, silver, molybdenum) by coprecipitation method, metal organic compound decomposition method, or Sol-gel method, where the particle size of the metal nanoparticles is greater than or equal to 1 nm and less than or equal to 5 nm; coat the surface of the obtained oxidized state of metal nanoparticles with a carbon layer with a thickness of 0.4 nm - 1 nm by hydrocarbon cracking method (250 - 500 °C).

[0074] Place the obtained carbon-coated metal nanoparticles in a sodium silicate solution, add aluminum nitrate and organic amine, and hydrothermally treat for 3 - 48 hours in a sealed environment at 150 °C - 230 °C. Zeolite ZSM-5 is generated, and the zeolite encapsulates metal nanoparticles coated with a carbon layer inside.

[0075] Filter out the obtained product and dry it at 100 - 120 °C for 3 - 10 hours. Then calcine it in air at 400 - 600 °C for 3 - 10 hours. Obtain a product with metal nanoparticles (oxidized state) encapsulated inside the zeolite (there is an annular gap of 0.4 - 1 nanometer between the zeolite shell and each metal nanoparticle, and the average diameter of the zeolite shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0076] Load the above catalyst product into a reactor and heat it to 450 - 600 °C. Feed the reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) into the reactor, and under a pressure of 0.1 - 3 MPa and a catalyst mass space velocity of 0.2 - 5 h -1 Under the condition, the catalyst (oxidized state) is reduced to the metallic state in a hydrogen atmosphere, and converted for 1 - 10 hours to generate aromatic hydrocarbon products. After the catalyst is deactivated due to carbon deposition, it is removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. Return the regenerated catalyst to the reactor and repeat the above steps for preparing aromatic hydrocarbons for continuous reaction.

[0077] In the aromatic hydrocarbon products prepared from the catalyst obtained based on the above method in this example, the highest hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach 75%.

[0078] Example 2

[0079] Prepare the oxidized state of metal nanoparticles (zinc, iron, manganese, silver, molybdenum) by coprecipitation method, metal organic compound decomposition method, or Sol-gel method, where the particle size of the metal nanoparticles is greater than or equal to 1 nm and less than or equal to 5 nm; coat the surface of the obtained oxidized state of metal nanoparticles with a carbon layer with a thickness of 0.4 nm - 1 nm by hydrocarbon cracking method (250 - 500 °C).

[0080] The obtained carbon-coated metal nanoparticles were dispersed in a solution containing tetraethyl orthosilicate, and an appropriate amount of aluminum sulfate and tetraethylammonium hydroxide were added. NaOH was added to adjust the pH of the solution to 11, and the obtained mixed solution was aged at room temperature for 8 - 12 hours. Subsequently, it was transferred to a hydrothermal reaction kettle and hydrothermally treated for 24 - 72 hours in a sealed environment at 150 - 200 °C. Metal nanoparticles coated with carbon were partially loaded inside the zeolite ZSM-11.

[0081] The obtained product was filtered out and dried at 100 - 120 °C for 3 - 10 hours. Then it was calcined in air at 400 - 600 °C for 3 - 10 hours. A product with metal nanoparticles (in oxidized state) encapsulated inside the zeolite was obtained (there is an annular gap of 0.4 - 1 nm between the zeolite shell and each metal nanoparticle, and the average diameter of the zeolite shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0082] The above catalyst product was loaded into a reactor and heated to 450 - 600 °C. The reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) were introduced into the reactor, and under a pressure of 0.1 - 3 MPa, the catalyst mass hourly space velocity was 0.2 - 5 h -1 Under this condition, the catalyst (in oxidized state) was reduced to the metallic state in a hydrogen atmosphere and converted for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst was deactivated due to carbon deposition, it was removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. The regenerated catalyst was returned to the reactor, and the above steps for preparing aromatic hydrocarbons were repeated for continuous reaction.

[0083] In the aromatic hydrocarbon products prepared from the catalyst obtained based on the above method in this example, the hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach up to 75%.

[0084] Example 3

[0085] The oxidized state of metal nanoparticles (zinc, iron, manganese, silver, molybdenum) was prepared by coprecipitation method, metal organic compound decomposition method, or Sol-gel method. The particle size of the metal nanoparticles was greater than or equal to 1 nm and less than or equal to 5 nm; the obtained oxidized state of metal nanoparticles was coated with a carbon layer with a thickness of 0.4 nm - 1 nm on the surface by hydrocarbon cracking method (250 - 500 °C).

[0086] The obtained carbon-coated metal nanoparticles were dispersed in deionized water, and an appropriate amount of aluminum sulfate and silica sol were added thereto. Subsequently, tetramethylammonium hydroxide was added to the solution as a template agent, and the pH of the solution was adjusted to 10 by NaOH. The obtained mixed solution was aged at room temperature for 24 hours. Subsequently, it was transferred to a hydrothermal reaction kettle and hydrothermally treated for 24 - 72 hours in a sealed environment at 120 °C. Y-type zeolite with carbon-coated metal nanoparticles partially loaded inside was generated.

[0087] Filter out the obtained product and dry it at 100 - 120 °C for 3 - 10 hours. Then calcine it in air at 400 - 600 °C for 3 - 10 hours. A product with metal nanoparticles (in oxidized state) encapsulated in zeolite is obtained (there is an annular gap of 0.4 - 1 nm between the zeolite shell and each metal nanoparticle, and the average diameter of the zeolite shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0088] Load the above catalyst product into a reactor and heat it to 450 - 600 °C. Feed the reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) into the reactor. Under a pressure of 0.1 - 3 MPa and a catalyst mass space velocity of 0.2 - 5 h -1 Under this condition, the catalyst (in oxidized state) is reduced to the metallic state in a hydrogen atmosphere, and the conversion is carried out for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst is deactivated due to carbon deposition, it is removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. The regenerated catalyst is returned to the reactor, and the above steps for preparing aromatic hydrocarbons are repeated for continuous reaction.

[0089] In the aromatic hydrocarbon products prepared from the catalyst obtained based on the above method in this embodiment, the highest hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach 75%.

[0090] Example 4

[0091] Prepare the oxidized state of metal nanoparticles (zinc, iron, manganese, silver, molybdenum) by coprecipitation method, metal organic compound decomposition method, or Sol - gel method. The particle size of the metal nanoparticles is greater than or equal to 1 nm and less than or equal to 5 nm; the obtained oxidized state of metal nanoparticles is coated with a carbon layer with a thickness of 0.4 nm - 1 nm on the surface by hydrocarbon cracking method (250 - 500 °C).

[0092] Mix the silicon source (sodium silicate) and the aluminum source (sodium aluminate) in a ratio of 40:1, add deionized water and stir to form a sol, and add the carbon-coated metal nanoparticles in small amounts and in multiple batches during the stirring process, and adjust the pH to 11 with NaOH. Subsequently, add hexamethyleneimine to the sol and stir to form a uniform gel. Transfer the gel to a reaction kettle and carry out a hydrothermal reaction at 180 °C for 120 hours to generate MCM - 22 type zeolite with carbon-coated metal nanoparticles partially loaded inside.

[0093] Filter out the obtained product and dry it at 100 - 120 °C for 3 - 10 hours. Then calcine it in air at 400 - 600 °C for 3 - 10 hours. A product with metal nanoparticles (in oxidized state) encapsulated in zeolite is obtained (there is an annular gap of 0.4 - 1 nm between the zeolite shell and each metal nanoparticle, and the average diameter of the zeolite shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0094] Load the above catalyst product into a reactor and heat it to 450 - 600 °C. Feed the reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) into the reactor. Under a pressure of 0.1 - 3 MPa, the catalyst mass space velocity is 0.2 - 5 h -1 Under these conditions, the catalyst (oxidized state) is reduced to the metallic state in a hydrogen atmosphere, and converted for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst is deactivated due to carbon deposition, it is removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. The regenerated catalyst is returned to the reactor, and the above steps for preparing aromatic hydrocarbons are repeated for continuous reaction.

[0095] In the aromatic hydrocarbon products prepared from the catalyst obtained based on the above method in this example, the hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach up to 75%.

[0096] Example 5

[0097] Prepare the oxidized state of metal nanoparticles (zinc, iron, manganese, silver, molybdenum) by coprecipitation method, metal organic compound decomposition method, or Sol - gel method. The particle size of the metal nanoparticles is greater than or equal to 1 nm and less than or equal to 5 nm; the oxidized state of the obtained metal nanoparticles is coated with a carbon layer with a thickness of 0.4 nm - 1 nm on the surface by hydrocarbon cracking method (250 - 500 °C).

[0098] Dissolve CTAB solution in deionized water and adjust the pH to 12 with ammonia water. Subsequently, add tetraethyl orthosilicate during stirring, and calculate and add sodium aluminate and carbon-coated metal nanoparticles according to a silicon-aluminum ratio of 40:1, and continuously stir for 6 hours until a homogeneous sol is formed. Transfer the sol to a reaction kettle and carry out hydrothermal reaction at 120 °C for 24 hours to generate MCM-41 type molecular sieve internally filled with carbon-coated metal nanoparticles.

[0099] Filter out the obtained product and dry it at 100 - 120 °C for 3 - 10 hours. Then calcine it in air at 400 - 600 °C for 3 - 10 hours. Obtain a product with metal nanoparticles (oxidized state) encapsulated in the molecular sieve (there is a 0.4 - 1 nanometer annular gap between the molecular sieve shell and each metal nanoparticle, and the average diameter of the molecular sieve shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0100] Load the above catalyst product into a reactor and heat it to 450 - 600 °C. Feed the reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) into the reactor. Under a pressure of 0.1 - 3 MPa, the catalyst mass space velocity is 0.2 - 5 h -1Under the conditions, the catalyst (in oxidized state) is reduced to the metallic state in a hydrogen atmosphere, and is transformed for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst is deactivated due to carbon deposition, it is removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. The regenerated catalyst is returned to the reactor, and the above steps for preparing aromatic hydrocarbons are repeated for continuous reaction.

[0101] In the aromatic hydrocarbon products prepared from the catalyst obtained in the above manner in this example, the highest hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach 65%. [[ID=—4]]

[0102] Example 6

[0103] Hydrothermal method is used to prepare nanoparticles. After mixing Zn(NO3)2 and urea in a molar ratio of 1:10, they are dissolved in deionized water, and a certain proportion of ethanol is added to the solution. The formed solution is subjected to hydrothermal reaction at 160 °C for 12 hours, and then centrifuged to obtain nano-ZnO particles as the metal nanoparticles. The obtained nano-ZnO particles are coated with a carbon layer of 0.4 - 1 nm on the surface by hydrocarbon cracking method (250 - 500 °C).

[0104] The obtained carbon-coated metal nanoparticles are placed in a sodium silicate solution, aluminum nitrate and organic amine are added, and hydrothermal treatment is carried out for 3 - 48 hours in a sealed environment at 150 °C - 230 °C. Molecular sieve ZSM-5 is generated, and the metal nanoparticles coated with a carbon layer are encapsulated inside the molecular sieve.

[0105] The obtained product is filtered out and dried at 100 - 120 °C for 3 - 10 hours. Then it is calcined in air at 400 - 600 °C for 3 - 10 hours. A product with metal nanoparticles (in oxidized state) encapsulated inside the molecular sieve is obtained (there is an annular gap of 0.4 - 1 nanometer between the molecular sieve shell and each metal nanoparticle, and the average diameter of the molecular sieve shell is 10 - 100 times the average diameter of the metal nanoparticles).

[0106] The above catalyst product is loaded into a reactor and heated to 450 - 600 °C. The reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) are introduced into the reactor, and under a pressure of 0.1 - 3 MPa, the catalyst mass space velocity is 0.2 - 5 h -1 Under the conditions, the catalyst (in oxidized state) is reduced to the metallic state in a hydrogen atmosphere, and is transformed for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst is deactivated due to carbon deposition, it is removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700 °C. The regenerated catalyst is returned to the reactor, and the above steps for preparing aromatic hydrocarbons are repeated for continuous reaction.

[0107] In the aromatic hydrocarbon products prepared from the catalyst obtained in the above manner in this example, the highest hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach 7 — 5%.

[0108] Example 7

[0109] Metal organic decomposition method was used to prepare nanoparticles. Co(NO3)3 was dissolved in methanol to prepare a 0.1M solution. Another methanol solution of 0.8M dimethylimidazole was prepared. The two solutions were mixed and stirred evenly. Then, triethylamine was added to accelerate crystallization, and it was aged at room temperature for 24 hours. After centrifugal separation, the sample was decomposed of organic ligands under an inert atmosphere to obtain nano-Co3O4 particles as metal nanoparticles. The obtained nano-Co3O4 particles were coated with a carbon layer of 0.4 - 1nm on the surface by hydrocarbon pyrolysis method (250 - 500°C).

[0110] The obtained carbon-coated metal nanoparticles were placed in a sodium silicate solution, and aluminum nitrate and organic amine were added. Under a sealed environment at 150°C - 230°C, hydrothermal treatment was carried out for 3 - 48 hours. Molecular sieve ZSM-5 was generated, and the metal nanoparticles coated with a carbon layer were encapsulated inside the molecular sieve.

[0111] The obtained product was filtered out and dried at 100 - 120°C for 3 - 10 hours. Then it was calcined in air at 400 - 600°C for 3 - 10 hours. A product with metal nanoparticles (oxidized state) encapsulated inside the molecular sieve was obtained (there was an annular gap of 0.4 - 1 nanometer between the molecular sieve shell and each metal nanoparticle, and the average diameter of the molecular sieve shell was 10 - 100 times that of the average diameter of the metal nanoparticles).

[0112] The above catalyst product was loaded into a reactor and heated to 450 - 600°C. The reaction raw materials (olefins or alcohols, with a hydrogen partial pressure of 10% - 50%) were introduced into the reactor. Under a pressure of 0.1 - 3MPa and a catalyst mass space velocity of 0.2 - 5h -1 conditions, the catalyst (oxidized state) was reduced to the metal state in a hydrogen atmosphere and converted for 1 - 10 hours to produce aromatic hydrocarbon products. After the catalyst was deactivated by carbon deposition, it was removed from the reactor and transferred to an oxygen-containing atmosphere for carbon burning regeneration at 500 - 700°C. The regenerated catalyst was returned to the reactor, and the above steps for preparing aromatic hydrocarbons were repeated for continuous reaction.

[0113] In the aromatic hydrocarbon products prepared by the catalyst obtained based on the above method in this example, the highest hydrocarbon group selectivity from olefins to aromatic hydrocarbons can reach 65%.

[0114] Each example in this specification is described in a progressive manner. Each example focuses on the differences from other examples. The same or similar parts among the examples can be referred to each other.

[0115] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0116] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0117] The above has introduced in detail a catalyst, its preparation method, and a method for preparing aromatic hydrocarbons based on the catalyst. Specific examples are used in this text to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the present application.

Claims

1. A catalyst, characterized in that The catalyst is configured to convert olefins or alcohols into aromatics under high hydrogen partial pressure, and the catalyst comprises a core-shell structure, the core-shell structure comprising a molecular sieve shell and a metal particle core located within the molecular sieve shell, the metal particle core consisting of a plurality of discrete metal nanoparticles, and each metal nanoparticle is isolated by a molecular sieve matrix; An annular gap is formed between the molecular sieve shell and the metal particle core, and the minimum distance of the annular gap is greater than the kinetic diameter of the aromatic hydrocarbon; the ratio of the average diameter of the molecular sieve shell to the average diameter of the metal particle core is greater than or equal to 10 and less than or equal to 100.

2. The catalyst according to claim 1, characterized in that The minimum distance of the annular gap between the molecular sieve shell and the metal particle core is greater than or equal to 0.4 nm and less than or equal to 1 nm.

3. The catalyst according to claim 1, characterized in that The average diameter of the metal particle core is greater than or equal to 1 nm and less than or equal to 5 nm.

4. The catalyst according to claim 1, characterized in that The molecular sieve shell includes at least one of the following: ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-22 molecular sieve, Y-type molecular sieve, MCM-22 molecular sieve, and MCM-41 molecular sieve.

5. The catalyst according to claim 1, characterized in that The metal nanoparticles include at least one of the following: zinc, iron, manganese, silver, molybdenum, nickel, chromium, and copper.

6. A method for preparing a catalyst, characterized in that: For preparing the catalyst according to any one of claims 1 to 5, the preparation method comprises: preparing metal nanoparticles in an oxidized state based on the first raw material; Treating the oxidized metal nanoparticles based on a hydrocarbon cracking method so that the surfaces of the metal nanoparticles are coated with a carbon layer, wherein the thickness of the carbon layer is greater than or equal to 0.4 nm and less than or equal to 1 nm; hydrothermally treating the metal nanoparticles coated with the carbon layer based on the second raw material to obtain a first product, wherein the first product includes a molecular sieve shell and a metal particle core located inside the molecular sieve shell, the metal particle core including a plurality of metal nanoparticles with a surface coated with the carbon layer, and the metal nanoparticles are isolated by a molecular sieve matrix; The first product is calcined to remove the carbon layer on the surface of the metal nanoparticles to obtain the catalyst.

7. The method for preparing the catalyst according to claim 6, characterized in that: The first raw material includes at least one of the following: nitrate, chloride, and an organic metal compound corresponding to the metal nanoparticles.

8. The method for preparing the catalyst according to claim 6, wherein: The second raw material is used to form the molecular sieve shell, and the second raw material includes a silicon source, an aluminum source, and a template agent, wherein the silicon source includes at least one of the following: silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and sodium silicate; The aluminum source includes at least one of the following: sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, aluminum nitrate, aluminum oxide, and aluminum chloride; The template agent includes at least one of the following: tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, hexamethyleneimine, hexadecyltrimethylammonium bromide, diethylamine, triethylamine, and 1,6-hexanediamine.

9. A method for preparing aromatic hydrocarbons based on a catalyst, characterized in that: The catalyst is the catalyst according to any one of claims 1 to 5, and the method comprises: Adding the catalyst into the reactor and heating the reactor to a preset temperature; Adding reaction raw materials to the reactor, controlling the catalyst to be at a preset mass space velocity, and converting the reaction raw materials under a preset pressure so that the reaction raw materials undergo aromatization reaction under a hydrogen atmosphere to obtain aromatic hydrocarbon products, wherein the reaction raw materials include a feed gas containing olefins or alcohols, and the hydrogen integrated pressure of the feed gas is 10% to 50%; The preset temperature is 450℃-600℃; the preset mass air velocity is 0.2h -1 -5h -1 ; The preset pressure is 0.1MPa-3MPa; the conversion time is 1-10h.

10. The method for preparing aromatic hydrocarbons based on a catalyst according to claim 9, characterized in that: After obtaining the aromatic hydrocarbon product, the method further comprises: When the activity of the catalyst drops to the target conversion rate, the catalyst is transferred to an oxygen-containing atmosphere for carbon burning treatment to remove carbon deposited on the surface of the catalyst to obtain a regenerated catalyst; The regenerated catalyst is added to the reactor, and the reaction raw materials are converted based on the regenerated catalyst to obtain the aromatic hydrocarbon product.

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