Solid acid catalyst as well as preparation method and application thereof

Abstract

The invention discloses a solid acid catalyst as well as a preparation method and application thereof. The solid acid catalyst comprises multistage self-assembled nano particle mordenite, a metal active component and an optional binder, wherein the minimum unit of the multistage self-assembled nano-particle mordenite is a primary particle, the primary particle is subjected to secondary assembly to form a lamellar structure, the lamellar structure is further assembled to form a flaky aggregate, and the multistage self-assembled nano-particle mordenite is obtained. The solid acid catalyst is used for a reaction for producing light aromatic hydrocarbon by converting polycyclic aromatic hydrocarbon, and has the advantages of high reaction activity and selectivity.

Description

Technical Field

[0001] The present invention belongs to the field of zeolites, and particularly relates to mordenite. Specifically, it relates to a solid acid catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] In the traditional petrochemical industry, heavy aromatics are mainly used to blend gasoline and diesel components and act as fossil fuels. However, with the development trend of oil product upgrading, it is required to further reduce the content of heavy aromatics in oil products. How to convert this part of the extruded heavy aromatics is a key technical problem faced by the future refining industry.

[0003] Common conversion and utilization of heavy aromatics focus on the research of their lightening to produce light aromatics. The LCO conversion technology (LCO-X) developed by UOP for LCO rich in polycyclic aromatic hydrocarbons belongs to this type of technology. For the catalytic reforming heavy fraction conversion technology, it is mainly completed through the lightening of heavy aromatics and the disproportionation and alkyl transfer units. For example, TAC9 developed by UOP is suitable for processing pure C9A / C 10 A aromatics, and TA series alkyl transfer catalysts are all suitable for processing raw materials containing a certain amount of monocyclic heavy aromatics. However, the above catalysts all have certain limitations on the content of polycyclic aromatic hydrocarbons in the raw materials, and the conversion efficiency of the catalysts for heavy aromatics is also relatively low. At present, there is no industrial report on the treatment of the whole fraction of catalytic reforming heavy aromatics. The lightening of heavy aromatics mainly involves the selective hydrogenation of polycyclic aromatic hydrocarbons, the cracking of monocyclic aromatic hydrocarbons, and the dealkylation reaction process. Among them, acidic molecular sieves are the key materials to realize this process.

[0004] For the lightening reaction of polycyclic aromatic hydrocarbons, the pore structure on the catalyst has an important influence on the diffusion and conversion of reactants. First, only when the molecular size is smaller than the pore diameter can it freely enter and reach the acidic sites for catalytic conversion. Second, the pore length of the molecular sieve has a significant influence on the diffusion of raw material and product molecules. In order to weaken the diffusion limitation of micropores as much as possible, improve the product selectivity, and increase the catalyst life, a hierarchical pore molecular sieve pore system containing mesopores and micropores can be constructed, that is, by enhancing the diffusion of reaction substrates and products. Synthesizing molecular sieves with nanoscale size is an important way to achieve enhanced diffusion. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a solid acid catalyst, a preparation method thereof, and an application thereof, which preferably solve the above problems, are used for the reaction of converting polycyclic aromatic hydrocarbons into light aromatics, have the advantages of high reaction activity and selectivity, and can be used in the industrial production of aromatic hydrocarbon conversion.

[0006] On the one hand, the present invention provides a solid acid catalyst, which comprises a hierarchically self-assembled nanoparticle mordenite, a metal active component and an optional binder; wherein, the minimum unit of the hierarchically self-assembled nanoparticle mordenite is a primary particle, the primary particles are secondarily assembled to form a lamellar structure, and the lamellar structures are further assembled to form a flaky aggregate, thereby obtaining the hierarchically self-assembled nanoparticle mordenite.

[0007] The metal active component is selected from at least one of Group VIII metals, Group VIIB metals, Group VIB metals and Group IIIA metals, preferably at least one of Pt, Pb, Re, Mo, Ni and Ga; and / or, the binder is selected from at least one of alumina, aluminum sol and pseudo-boehmite.

[0008] The specific surface area of the hierarchically self-assembled nanoparticle mordenite is 300-850 m 2 / g, and the external specific surface area is 50-600 m 2 / g; and / or, the primary particles are nanoparticles with a particle size of 5-300 nm; and / or,

[0009] The lamellar structure is circular or quasi-circular, with a thickness of 5-300 nm and a diameter or the maximum distance in the radial direction of 50-800 nm; and / or, the sizes of the flaky aggregates in all directions are independently 800-10,000 nm.

[0010] Based on the total weight of 100 wt% of the hierarchically self-assembled nanoparticle mordenite and the binder, the content of the mordenite is 30-95 wt%, and the content of the binder is 5-70 wt%, and the weight of the binder is based on the weight of alumina therein; and / or, based on the total weight of 100 wt% of the hierarchically self-assembled nanoparticle mordenite and the binder, the content of the metal active component is 0.05-10 wt%, preferably 0.3-5 wt%, wherein the weight of the metal active component is based on the weight of the metal element therein.

[0011] The second aspect of the present invention lies in providing a preparation method of a solid acid catalyst, and the preparation method includes: Step 1, first obtain the hierarchical self-assembled nanoparticle mordenite: (1.1) Mix water, a first silicon source, and a first structure-directing agent to obtain a first mixed system, stir and age the first mixed system to obtain a liquid seed; (1.2) Mix water, a second silicon source, and the liquid seed, adjust the pH to alkaline, and perform a first crystallization after stirring to obtain a first crystallization pre-product; (1.3) Add an aluminum source and a second structure-directing agent to the first crystallization pre-product, adjust the pH to alkaline, and perform a second crystallization to obtain a second crystallization pre-product; (1.4) Perform post-treatment on the second crystallization pre-product to obtain the hierarchical self-assembled nanoparticle mordenite; Step 2, load the metal active component on the mordenite molecular sieve, and optionally knead and form it with a binder; Step 3, dry and calcine to obtain the solid acid catalyst.

[0012] In Step 1: The first silicon source and the second silicon source are each independently selected from one or more of silicon dioxide, water glass, silica sol, ethyl silicate, sodium silicate, silica gel, and white carbon black; and / or, the aluminum source is selected from one or more of boehmite, pseudoboehmite, aluminum hydroxide, sodium metaaluminate, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide; and / or, the first structure-directing agent is selected from one or more of straight-chain alkylamines having 2 to 5 carbon atoms, tetra-C2-C5 alkyl ammonium halides, tetra-C2-C5 alkyl ammonium hydroxides, and ammonia water, preferably selected from one or more of ethylamine, hexylamine, ethylenediamine, hexamethylenediamine, tetraethylammonium bromide, tetraethylammonium hydroxide, tetramethylammonium bromide, tetramethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium bromide, tetrabutylammonium hydroxide, and ammonia water; and / or, the second structure-directing agent is selected from one or more of cyclic amine compounds, diammonium halides having more than 6 carbon atoms, and C10-C20 alkyl tri-C1-C5 alkyl ammonium halides, preferably selected from one or more of hexamethyleneimine, cyclohexylamine, hexamethylenediammonium bromide (HMBr2), cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and dodecyltrimethylammonium bromide.

[0013] In Step (1.1), the molar ratio of the first structure-directing agent to the first silicon source is 0.001 to 0.5, where the silicon source is counted in terms of the molar amount of silicon dioxide; and / or, in Step (1.3), the molar amount of the second structure-directing agent to the total molar amount of the first silicon source and the second silicon source is 0.0005 to 0.2, where the first silicon source and the second silicon source are each counted in terms of the molar amount of silicon dioxide; and / or, in Step (1.3), the ratio of the total molar amount of the first silicon source and the second silicon source to the molar amount of the aluminum source is 5 to 100, where the first silicon source and the second silicon source are each counted in terms of the molar amount of silicon dioxide, and the aluminum source is counted in terms of the molar amount of alumina.

[0014] In step (1.1), the stirring is carried out for 1 to 24 h; and / or, the aging is carried out at 50 to 120 °C for 3 to 96 h; and / or, the stirring in step (1.2) and the first crystallization are carried out in a pressure crystallization kettle, and the temperature of the first crystallization is 60 to 150 °C, preferably 80 to 120 °C; and / or, the time of the first crystallization is 1 to 48 h; and / or, in step (1.3), the second crystallization is carried out in a pressure crystallization kettle, and the temperature of the second crystallization is 130 to 220 °C; and / or, the time of the second crystallization is 5 to 72 h; and / or, the post-treatment in step (1.4) includes filtration, ion exchange, filtration, and washing.

[0015] In step 2, the loading includes: preparing a precursor solution of the metal active component by at least one of the incipient wetness impregnation method, the spray drying method, and the stirring evaporation method; preferably, the precursor solution of the metal active component is an aqueous solution of a compound containing the metal active component, and preferably its concentration is 0.01 to 5 mol / L.

[0016] In step 2, when the binder is used, the weight ratio of the binder to the hierarchically self-assembled nanoparticle mordenite is 1:(0.05 to 2), preferably 1:(0.2 to 1), wherein the weight of the binder is based on the weight of alumina therein.

[0017] The third aspect of the present invention is to provide a solid acid catalyst obtained by using the preparation method described in the second aspect of the present invention.

[0018] The fourth aspect of the present invention is to provide the application of the solid acid catalyst in the upgrading of inferior aromatics, especially polycyclic aromatic hydrocarbons.

[0019] The fifth aspect of the present invention is to provide a method for upgrading polycyclic aromatic hydrocarbons, including: in a hydrogen atmosphere, contacting the polycyclic aromatic hydrocarbons with the solid acid catalyst described in the first aspect of the present invention or the solid acid catalyst obtained by using the preparation method described in the second aspect of the present invention; preferably, the conditions of the contact include: the temperature is 350 - 460 °C, the pressure is 2 - 5 MPa, the hydrogen-hydrocarbon molecular ratio is 2 - 8, and the weight hourly space velocity of the feed mass is 0.5 - 5 h -1 ; preferably, the polycyclic aromatic hydrocarbons include aromatics with 9 or more carbon atoms and naphthalene series; preferably, the aromatics with 9 or more carbon atoms account for 50 - 100 wt%, and the content of the naphthalene series accounts for 0 - 50 wt%; more preferably, the aromatics with 9 or more carbon atoms account for 80 - 99.5 wt%, and the naphthalene series accounts for 0.5 - 20 wt%.

[0020] In the ranges and any values disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0021] Compared with the prior art, the present invention has the following beneficial effects: It is used for the reaction of polycyclic aromatic hydrocarbon conversion to produce light aromatic hydrocarbons, and has the advantages of high reaction activity and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Showing the SEM morphology of the lamellar structure obtained during the preparation process of Example 1;

[0023] Figure 2 Showing the SEM morphology of the final aggregate (Product A1) obtained in the preparation of Example 1;

[0024] Figure 3 Showing the X-ray diffraction pattern of Product A1 obtained in Example 1, and it can be seen that it has the MOR crystal phase. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite with these descriptions.

[0026] One of the purposes of the present invention is to provide a solid acid catalyst, which includes hierarchically self-assembled nanoparticle mordenite, a metal active component, and an optional binder; wherein, the minimum unit of the hierarchically self-assembled nanoparticle mordenite is a primary particle, the primary particles are secondarily assembled to form a lamellar structure, and the lamellar structure is further assembled to form a flaky aggregate to obtain the hierarchically self-assembled nanoparticle mordenite.

[0027] In the prior art, the morphology of mordenite is generally rod-shaped crystals with regular geometric shapes. The prior art mainly involves blocky aggregated nanomaterials such as strip-shaped, disk-shaped, and spherical. However, such blocky aggregated nanomaterials have defects of slow diffusion rate and unsmooth diffusion channels in actual applications, resulting in the problem that the diffusion performance is not suitable for treating heavy polycyclic aromatic hydrocarbon raw materials. And the flaky aggregate described in the present invention can be spherical, quasi-spherical, or other three-dimensional structures aggregated by flakes. The flaky aggregate has the MOR structure and belongs to mordenite.

[0028] In a preferred embodiment, the specific surface area of the hierarchically self-assembled nanoparticle mordenite is 300 to 850 m 2 / g, and the external specific surface area is 50 to 600 m 2 / g.

[0029] In a further preferred embodiment, the specific surface area of the hierarchically self-assembled nanoparticle mordenite is 450 to 600 m 2 / g, and the external specific surface area is 100 to 300 m 2 / g (preferably 150 to 300 m 2 / g).

[0030] For example, the specific surface area of the hierarchically self-assembled nanoparticle mordenite can be 300 m 2 / g, 400 m 2 / g, 500 m 2 / g, 600 m 2 / g, 700 m 2 / g, 800 m 2 / g or 850 m 2 / g or any value between the above values or the numerical range between any two of the above values. The external specific surface area can be 50 m 2 / g, 100 m 2 / g, 200 m 2 / g, 300 m 2 / g, 400 m 2 / g, 500 m 2 / g or 600 m 2 / g or any value between the above values or the numerical range between any two of the above values.

[0031] In a preferred embodiment, the primary particles are nanoparticles with a particle size of 5 to 300 nm; and / or, the lamellar structure is circular or quasi-circular with a thickness of 5 to 300 nm, and its diameter or the maximum distance in the radial direction is 50 to 800 nm; and / or, the sizes of the sheet-like aggregates in all directions are independently 800 to 10,000 nm.

[0032] Among them, the particle size of the primary particles is 5 nm, 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm or 300 nm, or any value between the above values, or a numerical range between any two of the above values. The thickness of the lamellar structure can be 5 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm or 200 nm. The diameter of the lamellar structure or the maximum distance in the radial direction is 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm or 800 nm, or any value between the above values, or a numerical range between any two of the above values. The dimensions of the flaky aggregates in each direction can be independently 800 nm, 900 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm, 6000 nm, 7000 nm, 8000 nm, 9000 nm or 10000 nm, or any value between the above values, or a numerical range between any two of the above values.

[0033] In a further preferred embodiment, the particle size of the primary particles is 20 - 200 nm, and / or the thickness of the lamellar structure is 20 - 200 nm, and / or the diameter of the lamellar structure or the maximum distance in the radial direction is 100 - 800 nm.

[0034] In a preferred embodiment, the ratio of the amount of acid on the outer surface to the total amount of acid of the hierarchical self - assembled nano - particle mordenite is 0.15 - 0.6, preferably 0.2 - 0.5, for example 0.15, 0.2, 0.3, 0.4, 0.5 or 0.6, or any value between the above values, or a numerical range between any two of the above values.

[0035] The morphology of the hierarchical self - assembled nano - particle mordenite of the present invention has a multi - level aggregated self - assembled morphology. While improving the high - efficiency mass transfer performance of the solid acid catalyst, it mainly solves the problem of low activity and selectivity of the solid acid catalyst in the aromatics alkyl transfer reaction. This solid acid catalyst is suitable for treating heavy aromatics and polycyclic aromatic hydrocarbons containing C9 and above to produce benzene, toluene and xylene, and has the characteristics of high activity and good catalyst stability. It can be used in the industrial production of lightening conversion of polycyclic aromatic hydrocarbons such as selective hydrocracking of polycyclic aromatic hydrocarbons.

[0036] In a preferred embodiment, the metal active component is selected from at least one of Group VIII metals, Group VIIB metals, Group VIB metals, and Group IIIA metals, preferably at least one of Pt, Pb, Re, Mo, Ni, and Ga.

[0037] In a preferred embodiment, the binder is selected from at least one of alumina, aluminum sol, and pseudo-boehmite.

[0038] In a preferred embodiment, based on 100 wt% of the total weight of the catalyst, the content of the metal active component is 0.05 - 10 wt%, preferably 0.3 - 5 wt%, for example 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%, wherein the weight of the metal active component is based on the weight of the metal element therein.

[0039] In a further preferred embodiment, based on 100 wt% of the total weight of the catalyst, the content of the mordenite is 30 - 95 wt%, and the content of the binder is 5 - 70 wt%; preferably, the content of the mordenite is 50 - 85 wt%, and the content of the binder is 15 - 50 wt%, and the weight of the binder is based on the weight of alumina therein.

[0040] For example, based on 100 wt% of the total weight of the catalyst, the content of the mordenite is 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, or 95 wt%, and the content of the binder is 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or 70 wt%.

[0041] The second object of the present invention is to provide a method for preparing a solid acid catalyst, preferably for preparing the solid acid catalyst described in the first object of the present invention, and the preparation method includes:

[0042] Step 1, first obtain the hierarchical self-assembled nanoparticle mordenite: (1.1) Mix water, the first silicon source, and the first structure-directing agent to obtain a first mixed system, stir and age the first mixed system to obtain a liquid seed; (1.2) Mix water, the second silicon source, and the liquid seed, adjust the pH to alkaline, and perform the first crystallization after stirring to obtain a first crystallization pre-product; (1.3) Add an aluminum source and the second structure-directing agent to the first crystallization pre-product, adjust the pH to alkaline, and perform the second crystallization to obtain a second crystallization pre-product; (1.4) Perform post-treatment on the second crystallization pre-product to obtain the hierarchical self-assembled nanoparticle mordenite;

[0043] Step 2, load the metal active component on the mordenite molecular sieve, and then optionally knead and shape it with a binder;

[0044] Step 3, dry and calcine to obtain the solid acid catalyst.

[0045] Among them, the liquid crystal seeds obtained in step (1.1) have no crystal form. Therefore, in step (1.1), it is preferably not to add an aluminum source and an alkali.

[0046] In the present invention, the hierarchical self-assembled nanoparticle mordenite is obtained by a two-step crystallization method. On the one hand, due to the relatively small primary particles (preferably 5-100 nm), the acidic sites are fully exposed. On the other hand, the secondary flaky structure [preferably with a thickness of (5-100 nm) * a diameter of (100-800 nm)] is beneficial to shortening the diffusion long range, and is particularly suitable for the lightening conversion of inferior aromatics, especially polycyclic aromatic hydrocarbons, to increase the production of BTX. And the overall self-assembled particles have a micron-sized dimension, which is convenient for the filtration and washing of the molecular sieve.

[0047] In a preferred embodiment, in step 1, the first silicon source and the second silicon source are each independently selected from one or more of silicon oxide, water glass, silica sol, tetraethyl orthosilicate, sodium silicate, silica gel, and precipitated silica.

[0048] In a preferred embodiment, in step 1, the aluminum source is selected from one or more of boehmite, pseudo-boehmite, aluminum hydroxide, sodium metaaluminate, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide.

[0049] In a preferred embodiment, in step 1, the first structure-directing agent is selected from one or more of straight-chain alkylamines with C2-C5, tetra-C2-C5 alkylammonium halides, tetra-C2-C5 alkylammonium hydroxides, and ammonia water.

[0050] In a further preferred embodiment, in step 1, the first structure-directing agent is selected from one or more of ethylamine, hexylamine, ethylenediamine, hexamethylenediamine, tetraethylammonium bromide, tetraethylammonium hydroxide, tetramethylammonium bromide, tetramethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium bromide, tetrabutylammonium hydroxide, and ammonia water.

[0051] In the present invention, the function of the first structure-directing agent is to control the formation of the mordenite structure.

[0052] In a preferred embodiment, in step 1, the second structure-directing agent is selected from one or more of cyclic amine compounds, diammonium halides with more than C6, and C10-C20 alkyltri-C1-C5 alkylammonium halides.

[0053] In a further preferred embodiment, in step 1, the second structure-directing agent is selected from one or more of hexamethyleneimine, cyclohexylamine, hexamethonium bromide (HMBr2), cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and dodecyltrimethylammonium bromide.

[0054] In the present invention, the function of structure-directing agent two is to control the morphology, promote secondary assembly and flaky aggregation, mainly to promote the self-assembly of flaky aggregation.

[0055] In a preferred embodiment, in step (1.1), the molar ratio of structure-directing agent one to silicon source one is 0.001 - 0.5, where the silicon source is calculated in terms of the molar amount of silicon dioxide; and / or, in step (1.3), the molar amount of structure-directing agent two to the total molar amount of silicon source one and silicon source two is 0.0005 - 0.2, where the silicon source is calculated in terms of the molar amount of silicon dioxide.

[0056] For example, in step (1.1), the molar ratio of structure-directing agent one to silicon source one can be 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5 or any value between the above values or the numerical range between any two of the above values, where the silicon source is calculated in terms of the molar amount of silicon dioxide. In step (1.3), the ratio of the molar amount of structure-directing agent two to the total molar amount of silicon source one and silicon source two can be 0.0005, 0.005, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.09, 0.1, 0.12, 0.14, 0.16, 0.18 or 0.2 or any value between the above values or the numerical range between any two of the above values, where silicon source one and silicon source two are respectively calculated in terms of the molar amount of silicon dioxide.

[0057] In a further preferred embodiment, the molar ratio of structure-directing agent one to structure-directing agent two is 0.05 - 2.5, for example 0.05, 0.1, 0.5, 1, 1.5, 2 or 2.5.

[0058] In a preferred embodiment, in step (1.1), the molar ratio of water to silicon source one is 2 - 15; and / or, in step (1.2), the molar ratio of water to silicon source two is 10 - 20, where the silicon source one is calculated in terms of the molar amount of silicon dioxide.

[0059] For example, in step (1.1), the molar ratio of water to silicon source one can be 2, 4, 6, 8, 10, 12, 14 or 15 or any value between the above values or the numerical range between any two of the above values; and / or, in step (1.2), the molar ratio of water to silicon source two can be 10, 12, 14, 16, 18 or 20 or any value between the above values or the numerical range between any two of the above values.

[0060] In a preferred embodiment, in step (1.3), the total molar amount of the first silicon source and the second silicon source to the molar amount of the aluminum source is 5 to 100. For example, it can be 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100, or any value between the above values, or the numerical range between any two of the above values. Among them, the first silicon source and the second silicon source are respectively calculated in terms of the molar amount of silicon dioxide, and the molar amount of the aluminum source is calculated in terms of Al2O3.

[0061] In the present invention, the molar amount of the silicon source is calculated in terms of the molar amount of silicon dioxide.

[0062] In a preferred embodiment, in step (1.1), the stirring is carried out for 1 to 24 h; and / or, the aging is carried out at 50 to 120 °C for 3 to 96 h.

[0063] For example, in step (1.1), the stirring is carried out for 1 h, 5 h, 10 h, 15 h, 20 h or 24 h; and / or, the aging is carried out at 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C for 3 h, 5 h, 10 h, 20 h, 40 h, 60 h, 80 h or 96 h.

[0064] Among them, the aging in step (1.1) needs to be carried out at the above temperature, otherwise it will affect the seed crystal structure and size, and further affect the morphology of the final aggregate.

[0065] In a preferred embodiment, in step (1.2), the stirring and the first crystallization are carried out in a pressure crystallization kettle.

[0066] In a further preferred embodiment, the temperature of the first crystallization is 60 to 150 °C, preferably 80 to 120 °C; and / or, the time of the first crystallization is 1 to 48 h.

[0067] For example, the temperature of the first crystallization can be 60 °C, 80 °C, 100 °C, 120 °C, 140 °C or 150 °C; and / or, the time of the first crystallization can be 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h or 48 h.

[0068] In a preferred embodiment, in step (1.3), the second crystallization is carried out in a pressure crystallization kettle.

[0069] In a further preferred embodiment, the temperature of the second crystallization is 130 to 220 °C; and / or, the time of the second crystallization is 5 to 72 h.

[0070] For example, the temperature of the first crystallization may be 130°C, 150°C, 180°C, 200°C or 220°C; and / or, the time of the second crystallization may be 5h, 10h, 20h, 30h, 40h, 50h, 60h, 70h, or 72h.

[0071] In a preferred embodiment, the temperature of the first crystallization is lower than that of the second crystallization.

[0072] Among them, the inventor found through a large number of experiments that the control of the temperature of the first crystallization is extremely important for the secondary assembly. The reason may be that the first crystallization at a low temperature can inhibit rapid growth and ensure the occurrence of secondary assembly.

[0073] In a preferred embodiment, the pH is adjusted in steps (1.2) and (1.3) independently using an alkali source, preferably the pH is independently adjusted to 10 - 14, such as 10, 11, 12, 13 or 14.

[0074] Among them, an alkali source is further added independently in steps (1.2) and (1.3).

[0075] In a further preferred embodiment, the alkali source is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0076] In a preferred embodiment, the post-treatment in step (1.4) includes filtration, ion exchange, filtration, and washing. Preferably, the post-treatment is repeated multiple times.

[0077] In a further preferred embodiment, the ion exchange is carried out in an ion exchange solution, where: the ion exchange solution is selected from one or more of aqueous ammonium nitrate solution, aqueous ammonium chloride solution, aqueous hydrochloric acid solution, and aqueous sulfuric acid solution; and / or, the molar concentration of the ion exchange solution is 0.05 - 1mol / L, preferably 0.5 - 5mol / L; and / or, the ion exchange is carried out at 60 - 120°C (preferably 80 - 110°C).

[0078] For example, the molar concentration of the ion exchange solution is 0.05mol / L, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L, 0.9mol / L or 1mol / L; the ion exchange is carried out at 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C.

[0079] In a preferred embodiment, in step 2, the loading includes: preparing a precursor solution of the metal active component by at least one of incipient wetness impregnation method, spray drying method, and stirring evaporation method; preferably, the precursor solution of the metal active component is an aqueous solution of a compound containing the metal active component, and preferably its concentration is 0.01 - 5 mol / L, for example, 0.01 mol / L, 0.05 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L.

[0080] In a preferred embodiment, in step 2, when using the binder, the weight ratio of the binder to the hierarchically self-assembled nanoparticle mordenite is 1:(0.05 - 2), preferably 1:(0.2 - 1), where the weight of the binder is calculated based on the weight of alumina therein.

[0081] In a preferred embodiment, in step 3, the calcination conditions include: temperature of 450 - 550 °C and time of 2 - 10 h; preferably, temperature of 480 - 520 °C and time of 4 - 8 h.

[0082] For example, the calcination conditions include: temperature of 450 °C, 460 °C, 480 °C, 500 °C, 520 °C, 540 °C, or 550 °C, and time of 2 h, 4 h, 6 h, 8 h, or 10 h.

[0083] A third object of the present invention is to provide a solid acid catalyst obtained by using the preparation method described in the second object of the present invention.

[0084] A fourth object of the present invention is to provide the application of the solid acid catalyst described in the first object of the present invention or the solid acid catalyst obtained by using the preparation method described in the second object of the present invention in the lightening of inferior aromatics, especially polycyclic aromatic hydrocarbons (converting and increasing the production of BTX).

[0085] A fifth object of the present invention is to provide a method for lightening polycyclic aromatic hydrocarbons, including: contacting the polycyclic aromatic hydrocarbons with the solid acid catalyst described in the first object of the present invention or the solid acid catalyst obtained by using the preparation method described in the second object of the present invention under a hydrogen atmosphere.

[0086] In a preferred embodiment, the contacting conditions include: temperature of 350 - 460 °C, pressure of 2 - 5 MPa, hydrogen-hydrocarbon molecular ratio of 2 - 8, and the weight hourly space velocity of the feed mass is 0.5 - 5 h -1 。

[0087] For example, the conditions of the contact include: a temperature of 350 °C, 360 °C, 380 °C, 400 °C, 420 °C, 440 °C or 460 °C, a pressure of 2 MPa, 3 MPa, 4 MPa or 5 MPa, a hydrogen-hydrocarbon molecular ratio of 2, 3, 4, 5, 6, 7 or 8, and a weight hourly space velocity of the feed mass of 0.5 h -1 、1 h -1 、2 h -1 、3 h -1 、4 h -1 or 5 h -1 。

[0088] In a preferred embodiment, the polycyclic aromatic hydrocarbons include aromatic hydrocarbons with 9 or more carbon atoms and naphthalene series compounds; preferably, the aromatic hydrocarbons with 9 or more carbon atoms account for 50-100 wt%, and the content of naphthalene series compounds accounts for 0-50 wt%; more preferably, the aromatic hydrocarbons with 9 or more carbon atoms account for 80-99.5 wt%, and the naphthalene series compounds account for 0.5-20 wt%.

[0089] For example, the polycyclic aromatic hydrocarbons include aromatic hydrocarbons with 9 or more carbon atoms and naphthalene series compounds; the aromatic hydrocarbons with 9 or more carbon atoms account for 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% or 100 wt%, and the content of naphthalene series compounds accounts for 0, 10 wt%, 20 wt%, 30 wt%, 40 wt% or 50 wt%.

[0090] Examples

[0091] The present invention will be specifically described below in conjunction with specific examples. It is necessary to point out here that the following examples are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0092] In addition, it should be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0093] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention. The technical solutions formed thereby belong to a part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0094] For the raw materials used in the examples and comparative examples, if not specifically defined, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0095]

Example 1

[0096] Seed preparation: A mixture is obtained by combining silicon source 1, structure-directing agent 1, and deionized water, followed by stirring and aging to obtain a liquid seed.

[0097] Silicon source 2, the above-mentioned liquid seed, and deionized water are mixed to form a mixture. The pH is adjusted to 13 - 14 using an alkali source. The above mixture is added to an autogenous pressure crystallization kettle, stirred at 50 °C for 2 hours, then heated to the first crystallization temperature T1, and crystallized at this temperature for a time t1 to complete the first-step crystallization, obtaining crystallization product 1. Aluminum source and structure-directing agent 2 are added to crystallization product 1, the pH is adjusted to 13 - 14 using an alkali source, heated to the second crystallization temperature T2, and crystallized again at this temperature for a time t2 to complete the second-step crystallization, obtaining crystallization product 2. After completion, it is cooled to room temperature and filtered to obtain a sodium-type molecular sieve. The obtained sodium-type molecular sieve is exchanged with a 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed until neutral, and the exchange is repeated 2 times, and dried at 120 °C for 12 hours to obtain product A1.

[0098] 60 grams of A1 are each taken and impregnated with a certain amount of nickel nitrate solution by the incipient wetness impregnation method. The concentration of the nickel nitrate solution is 1 mol / L (with the metal Ni loading accounting for 1.5 wt% of the total catalyst mass), and kneaded with 38.5 grams of alumina, dried at 120 °C for 12 hours, and calcined at 500 °C for 8 hours to prepare catalyst B1.

[0099]

Example 2

[0100] Seed preparation: A mixture is obtained by combining silicon source 1, structure-directing agent 1, and deionized water, followed by stirring and aging to obtain a liquid seed.

[0101] Silicon source 2, the above-mentioned liquid seed, and deionized water are mixed to form a mixture. The pH is adjusted to 13 - 14 using an alkali source. The above mixture is added to an autogenous pressure crystallization kettle, stirred at 50 °C for 2 hours, then heated to the first crystallization temperature T1, and crystallized at this temperature for a time t1 to complete the first-step crystallization, obtaining crystallization product 1. Aluminum source and structure-directing agent 2 are added to crystallization product 1, the pH is adjusted to 13 - 14 using an alkali source, heated to the second crystallization temperature T2, and crystallized again at this temperature for a time t2 to complete the second-step crystallization, obtaining crystallization product 2. After completion, it is cooled to room temperature and filtered to obtain a sodium-type molecular sieve. The obtained sodium-type molecular sieve is exchanged with a 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed until neutral, and the exchange is repeated 2 times, and dried at 120 °C for 12 hours to obtain product A2.

[0102] 60 g of A2 were taken respectively and impregnated with a certain amount of nickel nitrate solution by the incipient wetness impregnation method. The concentration of the nickel nitrate solution was 0.5 mol / L (with the metal Ni loading accounting for 1.8 wt% of the total catalyst mass), and then kneaded with 38.2 g of alumina, dried at 120 °C for 12 hours, and calcined at 500 °C for 8 hours to prepare catalyst B2.

[0103]

Example 3

[0104] Seed preparation: A mixture was obtained by mixing silicon source I, structure-directing agent I, and deionized water, stirred and aged to obtain a liquid seed.

[0105] A mixture was obtained by mixing silicon source II, the above liquid seed, and deionized water, and the pH was adjusted to 13 - 14 with an alkali source. The above mixture was added to an autogenous pressure crystallization kettle, stirred at 50 °C for 2 hours and then heated to the first crystallization temperature T1, and crystallized at this temperature for a time of t1 to complete the first-step crystallization to obtain crystallization product I. An aluminum source and structure-directing agent II were added to crystallization product I, the pH was adjusted to 13 - 14 with an alkali source, heated to the second crystallization temperature T2, and crystallized again at this temperature for a time of t2 to complete the second-step crystallization to obtain crystallization product II. After completion, it was cooled to room temperature and filtered to obtain a sodium-type molecular sieve. The obtained sodium-type molecular sieve was exchanged with 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed to neutrality, and the exchange was repeated 2 times, and dried at 120 °C for 12 hours to obtain product A3.

[0106] 60 g of A3 were taken respectively and impregnated with a certain amount of nickel nitrate solution by the incipient wetness impregnation method. The concentration of the nickel nitrate solution was 0.5 mol / L (with the metal Ni loading accounting for 1.8 wt% of the total catalyst mass), and then kneaded with 38.2 g of alumina, dried at 120 °C for 12 hours, and calcined at 500 °C for 8 hours to prepare catalyst B3.

[0107]

Example 4

[0108] Seed preparation: A mixture was obtained by mixing silicon source I, structure-directing agent I, and deionized water, stirred and aged to obtain a liquid seed.

[0109] Mix the silicon source II, the liquid seed crystals, and deionized water to obtain a mixture. Adjust the pH to 13 - 14 with an alkali source. Add the above mixture to an autogenous pressure crystallization kettle, stir at 50 °C for 2 hours, then raise the temperature to the first crystallization temperature T1, and crystallize at this temperature for a time of t1 to complete the first - step crystallization, obtaining crystallization product I. Add an aluminum source and structure - directing agent II to crystallization product I, adjust the pH to 13 - 14 with an alkali source, raise the temperature to the second crystallization temperature T2, and crystallize again at this temperature for a time of t2 to complete the second - step crystallization, obtaining crystallization product II. After completion, cool to room temperature and filter to obtain a sodium - type molecular sieve. The obtained sodium - type molecular sieve is exchanged with a 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed to neutral, and the exchange is repeated 2 times, and dried at 120 °C for 12 hours to obtain product A4.

[0110] Weigh 60 g of A4 respectively, and use the incipient - wetness impregnation method to impregnate a certain amount of nickel ammonium nitrate solution. The concentration of the nickel nitrate solution is 0.5 mol / L (with the metal Ni loading accounting for 1.5 wt% of the total catalyst mass), and knead it with 38.5 g of alumina to form a shape, dry at 120 °C for 12 hours, and calcine at 500 °C for 8 hours to prepare catalyst B4.

[0111]

Example 5

[0112] Weigh 60 g of A1 respectively, and use the incipient - wetness impregnation method to impregnate a certain amount of nickel nitrate solution. The concentration of the nickel nitrate solution is 1 mol / L (with the metal Ni loading accounting for 2.0 wt% of the total catalyst mass), and knead it with 38.5 g of alumina to form a shape, dry at 120 °C for 12 hours, and calcine at 500 °C for 8 hours to prepare catalyst B5.

[0113]

Example 6

[0114] Weigh 60 g of A1 respectively, and use the incipient - wetness impregnation method to impregnate a certain amount of nickel nitrate solution. The concentration of the nickel nitrate solution is 1 mol / L (with the metal Ni loading accounting for 1.5 wt% of the total catalyst mass), and knead it with 20.5 g of alumina to form a shape, dry at 120 °C for 12 hours, and calcine at 500 °C for 8 hours to prepare catalyst B6.

[0115]

Comparative Example 1

[0116] Take 60 g of commercially available mordenite A5, and use the incipient - wetness impregnation method to impregnate a certain amount of nickel nitrate solution. The concentration of the ammonium heptamolybdate solution is 1 mol / L (with the metal Ni loading accounting for 1.5 wt% of the total catalyst mass), and knead it with 38.5 g of alumina to form a shape, dry at 120 °C for 12 hours, and calcine at 500 °C for 8 hours to prepare catalyst B7.

[0117]

Comparative Example 2

[0118] Seed preparation: Mix silicon source 1, structure-directing agent 1, and deionized water to obtain mixture 1 (without aging).

[0119] Mix silicon source 2, mixture 1, and deionized water to obtain mixture 2. Adjust the pH to 13 - 14 with a base source. Add the above mixture to an autogenous pressure crystallization kettle, stir at 50 °C for 2 hours, then raise the temperature to the first crystallization temperature T1, and crystallize at this temperature for a time t1 to complete the first-step crystallization, obtaining crystallization product 1. Add an aluminum source and structure-directing agent 2 to crystallization product 1, adjust the pH to 13 - 14 with a base source, raise the temperature to the second crystallization temperature T2, and crystallize again at this temperature for a time t2 to complete the second-step crystallization, obtaining crystallization product 2. After completion, cool to room temperature and filter to obtain a sodium-type molecular sieve. The obtained sodium-type molecular sieve is exchanged with a 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed to neutrality, and the exchange is repeated 2 times. Dry at 120 °C for 12 hours to obtain product A6.

[0120] Take 60 g of A6 respectively, and impregnate a certain amount of nickel nitrate solution by the incipient wetness impregnation method. The concentration of the nickel nitrate solution is 1 mol / L (with the metal Ni loading accounting for 1.5% of the total catalyst mass), and knead it with 38.5 g of alumina to form a shape, dry at 120 °C for 12 hours, and calcine at 500 °C for 8 hours to prepare catalyst B8.

[0121]

Comparative Example 3

[0122] Seed preparation: Mix silicon source 1, structure-directing agent 1, aluminum source 2 (23.48 g of aluminum nitrate nonahydrate), base source 2 (5.33 g of sodium hydroxide), and deionized water to obtain a mixture, stir and age to obtain a liquid seed.

[0123] Mix silicon source 2 and deionized water to obtain a mixture. Adjust the pH to 13 - 14 with a base source. Add the above mixture to an autogenous pressure crystallization kettle, stir at 50 °C for 2 hours, then raise the temperature to the first crystallization temperature T1, and crystallize at this temperature for a time t1 to complete the first-step crystallization, obtaining crystallization product 1. Add an aluminum source and structure-directing agent 2 to crystallization product 1, raise the temperature to the second crystallization temperature T2, and crystallize again at this temperature for a time t2 to complete the second-step crystallization, obtaining crystallization product 2. After completion, cool to room temperature and filter to obtain a sodium-type molecular sieve. The obtained sodium-type molecular sieve is exchanged with a 0.3 mol / L ammonium nitrate aqueous solution at 95 °C for 4 hours, then filtered and washed to neutrality, and the exchange is repeated 2 times. Dry at 120 °C for 12 hours to obtain product A7.

[0124] 60 g of A8 were taken respectively and impregnated with a certain amount of nickel nitrate solution by the incipient wetness impregnation method. The concentration of the nickel nitrate solution was 1 mol / L (with the metal Ni loading accounting for 1.5% of the total catalyst mass), and then kneaded with 38.5 g of alumina, dried at 120 °C for 12 h, and calcined at 500 °C for 8 h to prepare catalyst B9.

[0125] Catalyst evaluation method

[0126] 15 g of the catalyst was loaded into a fixed-bed reactor, heated to 450 °C in a hydrogen atmosphere for reduction for 4 h and then cooled to 375 °C. 31.5 g of the reformed C9+ fraction per hour (with a naphthalene compound content of 5 wt%) was passed through the reactor once. -1 At a weight hourly space velocity of 2.1 h

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] Table 3 Comparison of catalyst performance

[0133]

[0134] Through comparison, it can be seen that the examples synthesized by the present invention show a higher conversion rate of C9+ heavy aromatics, especially the lightening conversion rate of naphthalene compounds, compared with the corresponding comparative examples. This is mainly due to the rich mesopores on the zeolite, which enhance the diffusion of heavy aromatic molecules on the zeolite, improve the contact of active sites, and also promote the selectivity of xylene in the products, indicating that the mordenite synthesized by this example has technical superiority.

[0135] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and all of these fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A solid acid catalyst, which comprises a hierarchically self-assembled nanoparticle mordenite, a metal active component and an optional binder; wherein, The minimum unit of the hierarchically self-assembled nanoparticle mordenite is a primary particle. The primary particles are secondarily assembled to form a lamellar structure, and the lamellar structures are further assembled to form a flaky aggregate, thereby obtaining the hierarchically self-assembled nanoparticle mordenite.

2. The solid acid catalyst according to claim 1, wherein the metal active component is selected from at least one of Group VIII metals, Group VIIB metals, Group VIB metals, and Group IIIA metals, preferably at least one of Pt, Pb, Re, Mo, Ni, and Ga; and / or the binder is selected from at least one of alumina, aluminum sol, and pseudo-boehmite.

3. The solid acid catalyst according to claim 1, wherein The specific surface area of the multi-stage self-assembled nanoparticle mordenite is 300 to 850 m 2 / g, and the external specific surface area is 50 to 600 m 2 / g; and / or, the primary particles are nanoparticles with a particle size of 5 to 300 nm; and / or the lamellar structure is circular or quasi-circular, with a thickness of 5 to 300 nm, and a diameter or the maximum distance in the radial direction of 50 to 800 nm; and / or the sizes of the flaky aggregates in all directions are independently 800 to 10,000 nm.

4. The solid acid catalyst according to any one of claims 1 to 3, wherein based on 100 wt% of the total weight of the catalyst, the content of the mordenite is 30 to 95 wt%, the content of the binder is 5 to 70 wt%, and the weight of the binder is calculated based on the weight of alumina therein; and / or based on 100 wt% of the total weight of the catalyst, the content of the metal active component is 0.05 to 10 wt%, preferably 0.3 to 5 wt%, and the weight of the metal active component is calculated based on the weight of the metal element therein.

5. A method for preparing a solid acid catalyst, preferably for preparing the solid acid catalyst according to any one of claims 1 to 4, the preparation method comprising: Step 1, first obtaining the hierarchically self-assembled nanoparticle mordenite: (1.1) Mixing water, a first silicon source, and a first structure-directing agent to obtain a first mixed system, stirring and aging the first mixed system to obtain a liquid seed; (1.2) Mixing water, a second silicon source, and the liquid seed, adjusting the pH to alkaline, and performing a first crystallization after stirring to obtain a first crystallization pre-product; (1.3) Adding an aluminum source and a second structure-directing agent to the first crystallization pre-product, adjusting the pH to alkaline, and performing a second crystallization to obtain a second crystallization pre-product; (1.4) Performing post-treatment on the second crystallization pre-product to obtain the hierarchically self-assembled nanoparticle mordenite; Step 2, loading the metal active component on the mordenite molecular sieve, and optionally kneading and shaping with a binder; Step 3, drying and calcining to obtain the solid acid catalyst.

6. The preparation method according to claim 5, characterized in that, In Step 1, the first silicon source and the second silicon source are each independently selected from one or more of silicon oxide, water glass, silica sol, ethyl silicate, sodium silicate, silica gel, and fumed silica; and / or the aluminum source is selected from one or more of boehmite, pseudo-boehmite, aluminum hydroxide, sodium meta-aluminate, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide; and / or The structure-directing agent 1 is selected from one or more of linear alkylamines having 2 to 5 carbon atoms, tetra-C2-C5 alkylammonium halides, tetra-C2-C5 alkylammonium hydroxides, and ammonia water, preferably selected from one or more of ethylamine, hexylamine, ethylenediamine, hexamethylenediamine, tetraethylammonium bromide, tetraethylammonium hydroxide, tetramethylammonium bromide, tetramethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium bromide, tetrabutylammonium hydroxide, and ammonia water; and / or, The structure-directing agent 2 is selected from one or more of cyclic amine compounds, diammonium halides having more than 6 carbon atoms, and C10-C20 alkyltri-C1-C5 alkylammonium halides, preferably selected from one or more of hexamethyleneimine, cyclohexylamine, hexamethylenediammonium bromide, cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and dodecyltrimethylammonium bromide.

7. The preparation method according to claim 5, characterized in that, In step (1.1), the molar ratio of the structure-directing agent 1 to the silicon source 1 is 0.001 to 0.5, wherein the silicon source is calculated in terms of the molar amount of silicon dioxide; and / or, In step (1.3), the molar amount of the structure-directing agent 2 to the total molar amount of the silicon source 1 and the silicon source 2 is 0.0005 to 0.2, wherein the silicon source 1 and the silicon source 2 are respectively calculated in terms of the molar amount of silicon dioxide; and / or, In step (1.3), the ratio of the total molar amount of the silicon source 1 and the silicon source 2 to the molar amount of the aluminum source is 5 to 100, wherein the silicon source 1 and the silicon source 2 are respectively calculated in terms of the molar amount of silicon dioxide, and the aluminum source is calculated in terms of the molar amount of aluminum oxide.

8. The preparation method according to claim 5, characterized in that, In step (1.1), the stirring is carried out for 1 to 24 h; and / or, the aging is carried out at 50 to 120 °C for 3 to 96 h; and / or, The stirring in step (1.2) and the first crystallization are carried out in an autoclave, the temperature of the first crystallization is 60 to 150 °C, preferably 80 to 120 °C; and / or, the time of the first crystallization is 1 to 48 h; and / or, In step (1.3), the second crystallization is carried out in an autoclave, the temperature of the second crystallization is 130 to 220 °C; and / or, the time of the second crystallization is 5 to 72 h; and / or, The post-treatment in step (1.4) includes filtration, ion exchange, filtration, and washing.

9. The preparation method according to any one of claims 5 to 8, characterized in that, In step 2, the loading includes: preparing a precursor solution of the metal active component, and adopting at least one of the incipient wetness impregnation method, spray drying method, and stirring evaporation method; preferably, the precursor solution of the metal active component is an aqueous solution of a compound containing the metal active component, and preferably its concentration is 0.01 to 5 mol / L.

10. The preparation method according to claim 9, characterized in that, In step 2, when the binder is used, the weight ratio of the binder to the hierarchically self-assembled nanoparticle mordenite is 1:(0.05 to 2), preferably 1:(0.2 to 1), wherein the weight of the binder is calculated in terms of the weight of aluminum oxide therein.

11. A solid acid catalyst obtained by the preparation method according to any one of claims 5 to 10.

12. Use of the solid acid catalyst according to any one of claims 1 to 4 or the solid acid catalyst obtained by using the preparation method according to any one of claims 5 to 10 in the lightening of inferior aromatics, especially polycyclic aromatic hydrocarbons.

13. A method for the lightening of polycyclic aromatic hydrocarbons, comprising: In a hydrogen atmosphere, the polycyclic aromatic hydrocarbons are contacted with the solid acid catalyst according to any one of claims 1 to 4 or the solid acid catalyst obtained by using the preparation method according to any one of claims 5 to 10; Preferably, the conditions for the contact include: a temperature of 350-460 °C, a pressure of 2-5 MPa, a hydrogen-hydrocarbon molecular ratio of 2-8, and a weight hourly space velocity of the feedstock of 0.5-5 h -1 ; Preferably, the polycyclic aromatic hydrocarbons include aromatics with 9 or more carbon atoms and naphthalene series compounds; preferably, the aromatics with 9 or more carbon atoms account for 50-100 wt%, and the content of naphthalene series compounds accounts for 0-50 wt%; more preferably, the aromatics with 9 or more carbon atoms account for 80-99.5 wt%, and the naphthalene series compounds account for 0.5-20 wt%.

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