Modified ZSM-5 molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a modified ZSM-5 molecular sieve, which comprises the following steps: carrying out hydrothermal aging treatment on a nano HZSM-5 molecular sieve to obtain a dealuminated nano HZSM-5 molecular sieve; and adding an inorganic alkali solution, a zinc-containing compound, a thio-compound and a mesoporous template agent into the dealuminated nano HZSM-5 molecular sieve, carrying out hydrothermal crystallization, drying, and roasting to obtain the modified ZSM-5 molecular sieve. The catalyst prepared from the modified ZSM-5 molecular sieve has high aromatization activity, and can ensure the gasoline yield and reduce the dry point retrogradation of the product.

Description

Technical Field

[0001] This invention relates to the field of catalyst materials, specifically to a modified ZSM-5 molecular sieve, its preparation method, and its applications. Background Technology

[0002] Aromatics are widely used in synthetic fibers, resins, rubber, and various fine chemicals, and are indispensable basic organic chemical raw materials. Furthermore, non-benzene aromatics are important blending components in the production of high-octane gasoline. In recent years, with the rapid development of downstream aromatic products, market demand for aromatics has continued to grow.

[0003] Low-carbon hydrocarbons and mixed hydrocarbons containing low-carbon hydrocarbons are byproducts of the petrochemical and refining industries, originating from ethylene projects, refineries, and natural gas purification processes. Converting these low-carbon hydrocarbons into aromatics through aromatization not only opens up new raw material sources for aromatics production but also optimizes the utilization of light hydrocarbon resources, thereby improving the economic efficiency of petrochemical enterprises.

[0004] Current research on the aromatization of low-carbon hydrocarbons mainly focuses on molecular sieve catalysts, particularly ZSM-5 molecular sieves. Nano-sized ZSM-5 molecular sieves exhibit excellent aromatization performance due to their short channels, numerous pores, low intracrystalline diffusion resistance, and good thermal stability. However, the small pore size (<0.6 nm), high acid content, and high proportion of acid on the outer surface of ZSM-5 molecular sieves limit the diffusion of reactants and products within the channels, promoting side reactions such as cracking and the formation of polycyclic aromatic hydrocarbons (PAHs). This results in insufficient reduction of olefins in the product, increased condensate, and a delayed product dry point, affecting the catalyst's olefin aromatization activity and gasoline yield. Consequently, it is difficult to meet the multiple requirements of significantly reducing olefins, maintaining octane number, and controlling distillation range during the upgrading of gasoline to the China VIB standard. Therefore, how to regulate the pore structure and acid distribution of ZSM-5 molecular sieves, increase molecular diffusion, suppress side reactions such as PAH formation, and leverage the synergistic effect of the catalyst's metal active centers and acid centers has become a key technical problem that needs to be solved in catalytic cracking gasoline hydroaromatics catalysts.

[0005] To address the aforementioned issues, current methods primarily employ post-treatment and template methods to expand the pores of ZSM-5 molecular sieves. Post-treatment methods, including hydrothermal treatment, acid treatment, and alkali treatment, all damage the molecular sieve framework structure and result in irregular mesopores, easily leading to decreased crystallinity. Template methods are expensive and complex, making industrialization difficult. Regarding the control of catalyst acid distribution to leverage the synergistic effect of metal active centers and acid centers, methods such as impregnation, ion exchange, and mechanical mixing are commonly used for metal additive modification. However, these methods often lead to metal additive accumulation on the support surface, clogging catalyst pores and affecting the accessibility of acidic and metal active centers within the pores.

[0006] For example, Chinese patent document CN112973772A discloses a gasoline aromatization and isomerization catalyst. The catalyst's support is a composite support obtained by mixing and molding nano-ZSM-5 particles grown along the 051 crystal plane, alumina, and an extrusion aid, followed by drying and calcination. When this composite support is impregnated with active metal components, the catalyst, when used in the olefin reduction reaction of high-olefin-content gasoline, can significantly reduce gasoline olefins while simultaneously increasing the product octane number by 1.7–7 units through isomerization and aromatization reactions. Furthermore, the desulfurization rate is >45%, the gasoline product yield is >98%, and the service life is >3000 hours. However, this composite support mainly focuses on regulating aromatization performance through the growth orientation of the molecular sieve crystal plane, without pore-expanding treatment. This makes it difficult to change the diffusion limitation of the catalyst micropore channels. Using the impregnation method makes it difficult for the main active metal component, zinc, to enter the interior of the molecular sieve micropores and react with the framework aluminum to generate a medium-strong L acid (ZnOH+) that is conducive to the aromatization reaction. This can easily lead to excessively strong surface acidity, exacerbating side reactions such as cracking and aromatic alkylation. It is difficult to solve problems such as insufficient olefin aromatization activity, delayed product dry point, and reduced gasoline yield.

[0007] Chinese patent document CN107876082A discloses an alkali-modified ZSM-5 molecular sieve, its preparation method, and its application. The method involves treating the ZSM-5 molecular sieve with an organic alkali solution followed by crystallization. This process expands the pores of the molecular sieve while simultaneously repairing its framework structure, increasing its crystallinity and producing a multi-level porous molecular sieve consisting of micropores, mesopores, and macropores. However, while expanding the pores with the organic alkali solution and combining crystallization to crystallize dissolved silicon atoms onto the molecular sieve surface framework to improve crystallinity and repair the framework structure, the added organic alkali solution acts as both an alkali and a micropore template agent. This makes it difficult to simultaneously achieve the dual effects of pore expansion and directional crystal growth. It also fails to directionally generate mesopores and effectively control the ratio of mesopores to macropores. Consequently, the resulting macropore structure is unfavorable to the shape selectivity of molecular sieve aromatization. When processing C4-C12 gasoline components, this can easily lead to over-reaction, generating large molecular aromatics, or excessive cracking. Furthermore, it struggles to address issues such as low gasoline yield and delayed product dry point in aromatization catalysts, failing to meet the requirements of China VIB standard gasoline production.

[0008] Chinese patent document CN116328823A discloses a method for preparing molecular sieves for the aromatization of olefins in gasoline fractions. Specifically, a ZSM-5 parent molecular sieve is added to a mixed alkaline solution of organic and inorganic bases for crystallization, followed by purification, ammonium exchange, and calcination to obtain a hollow ZSM-5 molecular sieve. Then, a metal salt solution is uniformly added dropwise to the hollow ZSM-5 molecular sieve, followed by equal-volume impregnation, drying, and calcination to obtain a ZSM-5 molecular sieve with high hydrothermal stability and aromatization activity. By utilizing a mixed alkaline solution of inorganic and organic bases to expand the pores of the molecular sieve, a mesoporous and hollow composite structure ZSM-5 molecular sieve is obtained. The combined effect of pore expansion by inorganic bases and recrystallization by organic bases improves the crystallinity and hydrothermal stability of the molecular sieve while simultaneously expanding the pores. However, while organic base solutions can be used as microporous templates to precisely control the morphology of molecular sieves, they are not easy to generate mesopores. Although the hollow structure obtained by impregnation is conducive to the entry of the active component zinc, it is difficult to react with the framework aluminum to generate a medium-strong L acid (ZnOH+) that is conducive to the aromatization reaction. This makes it difficult to solve problems such as the delayed drying point of the product and poor olefin aromatization activity.

[0009] Chinese patent document CN111151292A discloses an aromatization catalyst. A ZSM-5 molecular sieve matrix is ​​prepared by hydrothermal crystallization of a silicon source, an aluminum source, and a directing agent. The ZSM-5 molecular sieve matrix, water, and the directing agent are then mixed and hydrothermally treated to hydrothermally crystallize some of the non-framework silicon and aluminum in the matrix. After calcination, a microporous-macroporous ZSM-5 molecular sieve is obtained. The microporous-macroporous ZSM-5 molecular sieve is modified and expanded by adding a mixed alkali of inorganic and organic bases to obtain a multi-level microporous-mesoporous-macroporous ZSM-5 molecular sieve, which is then subjected to ammonium exchange. Finally, the ZSM-5 molecular sieve powder is ion-exchanged with a gallium metal salt solution to obtain a Ga-ZSM-5 molecular sieve. However, the hydrothermal crystallization step in this scheme addresses the utilization of non-framework aluminum and silicon in the ZSM-5 molecular sieve matrix and the formation of macroporous channels. It fails to resolve the issues of mesoporous irregularities and decreased crystallinity during subsequent alkali treatment. This reduces the accessibility of acidic centers and active metal centers within the channels, hindering aromatization activity. Furthermore, while the resulting macroporous channel structure helps improve anti-carbon deposition performance, it exacerbates side reactions such as cracking and aromatic alkylation, leading to a significant shift in the product's dry point and a reduction in gasoline yield.

[0010] In summary, most existing technologies expand pores and improve crystallinity through alkaline treatment and hydrothermal crystallization. However, these methods primarily involve crystallizing silicon atoms dissolved during alkaline modification onto the molecular sieve surface framework to form a coating structure. This alters the surface silicon-aluminum distribution, leading to a significant reduction in surface acid centers. While this helps improve the catalyst's resistance to carbon deposition, it also reduces the active sites for olefin to aromatic conversion, resulting in decreased catalyst activity. Therefore, developing aromatization catalysts that simultaneously maintain catalyst aromatization activity, ensure gasoline yield, and reduce product dry point shift is crucial. Summary of the Invention

[0011] In view of this, the present invention provides a modified ZSM-5 molecular sieve, its preparation method, and its application. Using hydrothermally aged dealullated nano-HZSM-5 molecular sieve as the matrix, potassium hydroxide or sodium hydroxide as the alkali source, zinc compounds and thiolated compounds are introduced, and a mesoporous template agent is added for hydrothermal crystallization. This simultaneously achieves the dual purpose of expanding pores and improving the crystallinity of the molecular sieve. In-situ modification of zinc enables effective regulation of the acid centers and metal active centers of the molecular sieve by metal sulfides, constructing highly efficient dehydrogenation centers, moderately hydrogenated centers, and suitable synergistic acid centers. The catalyst prepared using the modified ZSM-5 molecular sieve provided by the present invention solves the problems of low molecular sieve crystallinity in post-treatment pore-expansion methods, cumbersome template agent methods, easy accumulation of modifying agents on the carrier surface, and excessive surface acid centers. It effectively improves the aromatization activity of the catalyst while reducing the occurrence of side reactions such as cracking and the formation of polycyclic aromatic hydrocarbons, improving gasoline yield, and reducing the product dry point shift.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A method for preparing modified ZSM-5 molecular sieve includes the following steps:

[0014] Nano HZSM-5 molecular sieves are subjected to hydrothermal aging treatment to obtain dealuded nano HZSM-5 molecular sieves;

[0015] An inorganic alkaline solution, a zinc-containing compound, a thiolated compound, and a mesoporous template agent were added to the dealuded nano-HZSM-5 molecular sieve for hydrothermal crystallization. After drying and calcination, the modified ZSM-5 molecular sieve was obtained.

[0016] Using aluminum removed during hydrothermal aging of nano-HZSM-5 molecular sieve as the aluminum source and silicon removed during alkali treatment as the silicon source, hydrothermal crystallization was carried out in the presence of inorganic alkali and mesoporous template agent to achieve the purpose of expanding pores while improving the crystallinity of ZSM-5 molecular sieve, thus obtaining a highly crystalline microporous-mesoporous modified ZSM-5 molecular sieve.

[0017] Potassium or sodium salts are used as alkali sources to desilicate and expand the pores of molecular sieves. Potassium salts can also be used as catalyst modifiers to regulate acid distribution. Zinc-containing compounds are introduced during hydrothermal crystallization as modifiers, which is beneficial to the formation of medium-strong L-acids (ZnOH+), improves the dehydrogenation activity of the catalyst, and facilitates the aromatization reaction. Thio compounds form metal sulfides with the modifiers, which increases the degree of metal sulfidation and effectively regulates the acid centers of the molecular sieve, reduces Zn loss and catalyst cracking activity, and improves the aromatization activity and stability of the catalyst.

[0018] In one alternative embodiment, the molar ratio of the zinc-containing compound to the thio compound is 0.6 to 1.

[0019] In one optional embodiment, the molar ratio of the inorganic alkali to the mesoporous template agent in the inorganic alkali solution is 0.3–1. By controlling the ratio of the inorganic alkali to the mesoporous template agent, the pore structure and crystallinity of the molecular sieve can be adjusted.

[0020] In one optional embodiment, the mass ratio of the dealuded nano HZSM-5 molecular sieve, the thiolated compound, and the mesoporous template agent is 1:(0.06-0.36):(0.36-1.1).

[0021] In one optional embodiment, the hydrothermal aging treatment is performed at a temperature of 400–600°C and a mass hourly space velocity (HHSV) of 0.5–3 h⁻¹. -1 The time is 1 to 5 hours. Here, mass hourly space velocity (MHSV) refers to the mass flow rate of water vapor processed per unit mass of molecular sieve per unit time.

[0022] In one alternative embodiment, the hydrothermal crystallization is a programmed crystallization process; the programmed crystallization includes hydrothermal crystallization at 100–120°C for 12–24 hours, followed by hydrothermal crystallization at 160–200°C for 12–24 hours.

[0023] In one optional embodiment, the drying temperature is 120–180°C and the time is 60–180 min.

[0024] In one optional embodiment, the calcination temperature is 450–550°C and the time is 240–360 min.

[0025] In one alternative embodiment, the thio compound is selected from thioacetamide and / or ammonium thiosulfate.

[0026] In one alternative embodiment, the mesoporous template agent is selected from hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride.

[0027] In one optional embodiment, the inorganic alkaline solution is selected from inorganic sodium salt solution or inorganic potassium salt solution, wherein the inorganic potassium salt solution is selected from at least one of potassium carbonate solution, potassium hydroxide solution, and potassium bicarbonate solution; and the inorganic sodium salt solution is selected from at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate. Preferably, the concentration of the inorganic alkaline solution is 0.1–0.3 mol / L.

[0028] In one alternative embodiment, the zinc-containing compound is selected from at least one of zinc acetate dihydrate, zinc nitrate, and zinc sulfate.

[0029] In an optional embodiment, when the inorganic alkaline solution is selected from an inorganic sodium salt solution, the method further includes ammonium exchange of the modified ZSM-5 molecular sieve, washing until neutral, secondary drying, and secondary calcination. The sodium salt can react with the silicon on the molecular sieve framework, causing some silicon to detach from the framework, thereby forming a mesoporous structure. This facilitates molecular diffusion within the pores and improves mass transfer efficiency in the catalytic reaction. In an optional embodiment, the ammonium solution used in the ammonium exchange step is selected from ammonium chloride solution and / or ammonium nitrate solution; the concentration of the ammonium solution is 0.1–0.5 mol / L; preferably, the solid-liquid ratio of the modified ZSM-5 molecular sieve to the ammonium solution is 1 g:(5–15) mL.

[0030] In one optional embodiment, the ammonium exchange time is 0.5 to 4 hours.

[0031] In one optional embodiment, the secondary drying temperature is 120–180°C and the time is 60–180 min.

[0032] In one optional embodiment, the secondary calcination temperature is 450–550°C and the time is 240–360 min.

[0033] In an optional embodiment, when the inorganic alkaline solution is selected from an inorganic potassium salt solution, the step prior to drying includes separating the hydrothermal crystallization product and washing it with ammonium chloride solution to a pH of 8-9. Potassium salts can react with silicon on the molecular sieve framework, causing some silicon to detach from the framework, thereby forming a mesoporous structure. This helps promote molecular diffusion within the pores and improves mass transfer efficiency in catalytic reactions. Simultaneously, potassium salts can also act as a modifying agent, working with zinc to regulate the acid distribution and metal active centers of the molecular sieve, reducing acid strength and minimizing side reactions such as cracking and aromatic alkylation.

[0034] The present invention also provides a modified ZSM-5 molecular sieve prepared by the above-mentioned method.

[0035] The modified ZSM-5 molecular sieve prepared by the above-mentioned method of the present invention can be used in the preparation of catalysts.

[0036] The present invention also provides a method for preparing a low-carbon hydrocarbon aromatization catalyst support, comprising the following steps: mixing modified ZSM-5 molecular sieve with a binder and an extrusion aid, followed by drying and calcination to obtain a low-carbon hydrocarbon aromatization catalyst support;

[0037] The modified ZSM-5 molecular sieve is prepared by the above-described method for preparing modified ZSM-5 molecular sieve.

[0038] In one alternative embodiment, the extrusion aid is selected from at least one of guar gum powder, starch, and citric acid.

[0039] In one optional embodiment, the binder comprises a gel formed by mixing boehmite, nitric acid, and water; the mass ratio of the dry basis of the boehmite to the nitric acid and water is 1:(0.1-0.3):(2.3-3.2). After the boehmite, nitric acid, and water are mixed evenly to form a gel, it is left to stand for 24 hours before use.

[0040] In one optional embodiment, the mass ratio of the dry base of the binder to the modified ZSM-5 molecular sieve is (0.1 to 0.7):1.

[0041] In one optional embodiment, the mass ratio of the dry basis of the binder and the total amount of the modified ZSM-5 molecular sieve to the mass of the extrusion aid is 1:(0.01 to 0.05).

[0042] This invention also provides a method for preparing a low-carbon hydrocarbon aromatization catalyst, comprising the following steps:

[0043] The catalyst support was loaded with metal additives using an equal-volume impregnation method, and then dried and calcined to obtain the low-carbon hydrocarbon aromatization catalyst.

[0044] The catalyst support is selected from the low-carbon hydrocarbon aromatization catalyst support prepared by the above-mentioned method.

[0045] The metal additive is selected from at least one of Group VIII metal salts, Group IIIA metal salts, and Group IIIB metal salts.

[0046] In one optional embodiment, the Group VIII metal salt is selected from at least one of Co, Ni, Ru, etc.; the Group IIIA metal salt is selected from at least one of Ga, In, etc.; and the Group IIIB metal salt is selected from La. Utilizing the dehydrogenation properties of Group VIII metals, the dehydrogenation reaction step is further accelerated, the aromatization reaction performance is improved, zinc loss is reduced, and catalyst stability is enhanced. By utilizing the different electronegativity between Group IIIA metals and aluminum, the synergistic effect between Brønsted (B) and Lewis (L) acid sites is controlled, improving dehydrogenation activity and promoting the aromatization performance of low-carbon alkanes. Because Group IIIB metals have a smaller radius, they more easily enter the catalyst pores, effectively reducing the amount of strong acid, increasing the L / B ratio, and improving the catalyst's aromatization activity and selectivity, reducing side reactions such as cracking and aromatic alkylation, and increasing gasoline yield.

[0047] The present invention also provides a low-carbon hydrocarbon aromatization catalyst prepared by the above-mentioned method, comprising a support and an active component, wherein the support comprises nano-ZSM-5 molecular sieve and alumina; the active component comprises zinc, Group IIIA metal, Group VIII metal and Group IIIB metal; the zinc in the active component exists in the form of zinc sulfide, and the zinc sulfide is introduced by the modified nano-ZSM-5 molecular sieve.

[0048] In one optional embodiment, based on the mass of the low-carbon hydrocarbon aromatization catalyst as 100%, the content of the nano-low-silica ZSM-5 molecular sieve is 60% to 80%, the content of the active component as oxide is 5% to 17%, and the balance is alumina.

[0049] In one optional embodiment, based on the mass of the low-carbon hydrocarbon aromatization catalyst as 100%, and in terms of oxides, the active component contains 2.5% to 8% zinc, 1% to 2% group IIIA metals, 1% to 2% group VIII metals, and 1% to 2% group IIIB metals.

[0050] In an optional embodiment, the low-carbon hydrocarbon aromatization catalyst further includes potassium, and the potassium content, calculated as oxides, is 0.7% to 2.5%.

[0051] In one optional embodiment, the low-carbon hydrocarbon aromatization catalyst has a microporous to mesoporous structure with a specific surface area of ​​200–400 μm. 2 / g, total pore volume 0.2~0.4ml / g, external specific surface area 90~200m 2 / g, mesopore volume 0.1~0.3ml / g, mesopore volume percentage ≥60%.

[0052] In one optional embodiment, the total acidity of the low-carbon hydrocarbon aromatization catalyst is 0.10–0.25 mmol / g, the amount of strong Brønsted acid is 0.02–0.1 mmol / g, and the L / B ratio is 2–6.

[0053] This invention also provides an aromatization reaction of distillate oil, using a low-carbon hydrocarbon aromatization catalyst prepared by the above-described method, or the above-described low-carbon hydrocarbon aromatization catalyst; preferably, the hydrogen pressure of the aromatization reaction is 1.0–3.0 MPa, the temperature is 380–420 °C, and the space velocity is 1.0–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 200:1 to 400:1; more preferably, the low-carbon hydrocarbon aromatization catalyst is sulfided before the aromatization reaction, and the sulfidation conditions are: heating rate 20-30℃ / h, residence at 150℃ for 2-4h, residence at 230℃ for 6-8h, residence at 320℃ for 6-8h, and volume hourly space velocity 1-3h. -1 The hydrogen-to-oil ratio is 200:1 to 400:1, and the pressure is 1.0 to 3.0 MPa.

[0054] Compared with the prior art, the present invention has at least the following beneficial effects:

[0055] Beneficial Effect 1: The method for preparing modified ZSM-5 molecular sieve provided by this invention organically combines hydrothermal aging treatment, alkali treatment, and hydrothermal crystallization of molecular sieves, and adds thiolated compounds. It utilizes the aluminum removed during hydrothermal aging as the aluminum source and the silicon removed during alkali treatment as the silicon source. In the presence of inorganic alkali and mesoporous template agents, the nano-ZSM-5 molecular sieve is expanded while the non-framework aluminum and silicon in the system are further crystallized, improving the crystallinity and specific surface area of ​​ZSM-5 molecular sieve, increasing the mesoporous pore volume and proportion, and obtaining a highly crystalline microporous-mesoporous ZSM-5 molecular sieve. This modified ZSM-5 molecular sieve addresses several issues: conventional alkali treatment alone leads to decreased crystallinity; hydrothermal crystallization alone results in poor pore-expanding effects; and in combined methods, only non-framework silicon atoms crystallize on the catalyst surface framework, forming a coating structure that reduces surface acid centers and affects aromatization activity. Furthermore, by introducing an appropriate amount of mesopores and controlling the mesopore ratio, the diffusion of raw material and product molecules within the pores is increased. Catalysts prepared using this modified ZSM-5 molecular sieve help suppress side reactions such as the formation of polycyclic aromatic hydrocarbons, effectively improving catalyst aromatization activity and mitigating issues like delayed product drying point. By using potassium hydroxide or sodium hydroxide as the alkali source, the alkaline modification of metal additives by potassium can be utilized, and zinc-containing compounds and thiolated compounds can be introduced. The in-situ modification of potassium and zinc can effectively control the acid centers and metal active centers of molecular sieves. This solves the problems of metal modification additives accumulating on the support surface and clogging pores in conventional impregnation methods, and the difficulty of Zn reacting with skeletal aluminum to generate medium-strong L acid (ZnOH+) which is conducive to aromatization reaction. This effectively improves the catalyst L / B ratio, increases the proportion of medium-strong L acid, and effectively improves the catalyst aromatization activity and gasoline yield. Meanwhile, during the hydrothermal crystallization process, the reaction of thiocyanates with zinc compounds to generate zinc metal sulfide solves the problems of low sulfidation degree, uneven sulfide distribution, and weak bonding between metal and sulfide that exist in existing technologies where catalysts are prepared before sulfidation. This reduces metal loss during catalyst use and improves the catalyst's aromatization activity and stability. The generated metal sulfide also effectively regulates the acidity of the molecular sieve surface, reducing the amount of strong acid and external surface acidity. This solves the problems of high cracking activity in the initial stage of catalyst reaction, increased side reactions such as the formation of polycyclic aromatic hydrocarbons leading to reduced gasoline yield, and a significant shift in the dry point that exist in conventional preparation methods.

[0056] Beneficial Effect 2: The low-carbon hydrocarbon aromatization catalyst provided by the present invention, by using the above-mentioned specific modified molecular sieve as a support, can significantly improve the aromatization activity of low-carbon hydrocarbons, while ensuring gasoline yield and reducing product dry point shift. Detailed Implementation

[0057] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0058] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0059] Example 1

[0060] (1) Preparation of modified ZSM-5 molecular sieve

[0061] Weigh 120g of nano HZSM-5 molecular sieve and heat it at 550℃ for 3 hours. -1 Hydrothermal aging treatment was carried out for 3 hours under the specified conditions to obtain dealuded nano HZSM-5 molecular sieve S1.

[0062] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S1, followed by the sequential addition of 109g of hexadecyltrimethylammonium bromide, 14g of zinc acetate dihydrate, and 9.2g of ammonium thiosulfate. After stirring for 1h, solution S1 is obtained. Solution S1 is placed in a crystallization vessel and crystallized for the first time at 100℃ for 24h in a drying oven, followed by a second crystallization at 170℃ for 18h. The crystallized product is then filtered and washed with 0.5mol / L ammonium chloride solution until the pH of the product eluent is 9. The resulting filter cake is dried at 120℃ for 120min in a drying oven and calcined in a muffle furnace at 500℃ for 300min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M1 (i.e., modified ZSM-5 molecular sieve).

[0063] (2) Preparation of catalyst support

[0064] Weigh 143g of boehmite (70% dry basis) and add it to a kneader. Weigh 15g of 65% nitric acid and add it to 250g of water to prepare a dilute nitric acid solution. While stirring, slowly add the dilute nitric acid solution to the kneader and knead for 30 minutes to obtain binder N1. After taking it out, place it in a sealed self-sealing bag and let it sit for 24 hours before use.

[0065] Weigh 100g of modified microporous-mesoporous ZSM-5 molecular sieve M1, 3.75g of guar gum powder, and 102g of binder N1 and add them to a kneader. Knead for 30 minutes. The mixed material is then extruded, dried at 120℃, and calcined at 550℃ for 4 hours to obtain catalyst support Z1.

[0066] (3) Catalyst preparation

[0067] 3.4g gallium nitrate, 4.8g nickel nitrate and 3.3g lanthanum nitrate were weighed and dissolved in deionized water. After stirring until a clear solution was obtained, the volume was adjusted to 60ml with deionized water to obtain an impregnation solution. 100g of support Z1 was weighed and impregnated with the impregnation solution in an equal volume. After standing for 6 hours, it was dried at 120℃ for 4 hours and calcined at 500℃ for 4 hours to obtain catalyst A1.

[0068] Example 2

[0069] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0070] Weigh 120g of nano-HZSM-5 molecular sieve and heat it at 400℃ for 3.0h. -1 Under the condition of hydrothermal aging for 5 hours, dealuded nano HZSM-5 molecular sieve S2 was obtained.

[0071] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S2, followed by 96g of hexadecyltrimethylammonium bromide, 14g of zinc acetate dihydrate, and 9.2g of ammonium thiosulfate. After stirring for 1h, solution S2 is obtained. Solution S2 is placed in a crystallization vessel and crystallized for the first time at 120℃ in a drying oven for 12h, followed by a second crystallization at 200℃ for 12h. The crystallized product is then filtered and washed with 0.5mol / L ammonium nitrate solution until the pH of the product eluent is 8. The resulting filter cake is dried in a drying oven at 120℃ for 180min and calcined in a muffle furnace at 450℃ for 360min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M2 (i.e., modified ZSM-5 molecular sieve).

[0072] (2) Preparation of catalyst support

[0073] The preparation method of the catalyst support is similar to that in Example 1, except that in this example, 100g of modified microporous-mesoporous ZSM-5 molecular sieve M2, 3.75g of guar gum powder and 265g of binder N1 are weighed and added to a kneader for kneading, and then dried at 120℃ and calcined at 500℃ for 4 hours to obtain support Z2.

[0074] (3) Catalyst preparation

[0075] The catalyst preparation method is similar to that in Example 1, except that in this example, support Z2 is used and the volume is adjusted to 63 ml with deionized water, and then impregnated, dried and calcined to obtain catalyst A2.

[0076] Example 3

[0077] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0078] Weigh 120g of nano-HZSM-5 molecular sieve and heat it at 600℃ for 0.5h. -1 Under the condition of hydrothermal aging for 2 hours, dealuded nano HZSM-5 molecular sieve S3 was obtained.

[0079] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S3, followed by the sequential addition of 78g of hexadecyltrimethylammonium bromide, 47.0g of zinc nitrate hexahydrate, and 35.0g of ammonium thiosulfate. After stirring for 1h, solution S3 is obtained. Solution S3 is placed in a crystallization vessel and crystallized for the first time at 110℃ in a drying oven for 18h, followed by a second crystallization at 160℃ for 24h. The crystallized product is then filtered and washed with 0.5mol / L ammonium chloride solution until the pH of the product eluent is 9. The resulting filter cake is dried at 180℃ for 60min in a drying oven and calcined in a muffle furnace at 550℃ for 240min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M3 (i.e., modified ZSM-5 molecular sieve).

[0080] (2) Preparation of catalyst support

[0081] The preparation method of the catalyst support is similar to that in Example 1, except that in this example, 100g of modified microporous-mesoporous ZSM-5 molecular sieve M3, 4.0g of guar gum powder and 112g of binder N1 are weighed and added to a kneader for kneading, and then dried at 120℃ and calcined at 500℃ for 4 hours to obtain support Z3.

[0082] (3) Catalyst preparation

[0083] The preparation method of catalyst A3 is similar to that of Example 1, except that in this example, 5.6g of gallium nitrate, 7.9g of nickel nitrate, and 5.4g of lanthanum nitrate were weighed, dissolved in deionized water, stirred evenly to obtain a clear solution, and then diluted to 60ml with deionized water; 100g of support Z3 was weighed and impregnated with an equal volume, allowed to stand for 6 hours, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours to obtain catalyst A3.

[0084] Example 4

[0085] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0086] Weigh 120g of nano HZSM-5 molecular sieve and heat it at 550℃ for 3 hours. -1 Hydrothermal aging treatment was carried out under the conditions for 1 hour to obtain dealuded nano HZSM-5 molecular sieve S4.

[0087] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S4, followed by 91g of hexadecyltrimethylammonium bromide, 26.5g of zinc sulfate heptahydrate, and 16.8g of ammonium thiosulfate. After stirring for 1h, solution S4 is obtained. Solution S4 is placed in a crystallization vessel and crystallized for the first time at 100℃ for 18h in a drying oven, followed by a second crystallization at 180℃ for 24h. The crystallized product is then filtered and washed with 0.3mol / L ammonium chloride solution until the pH of the product eluent is 8. The resulting filter cake is dried at 150℃ for 90min in a drying oven and calcined in a muffle furnace at 500℃ for 240min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M4 (i.e., modified ZSM-5 molecular sieve).

[0088] (2) Preparation of catalyst support

[0089] The preparation method of catalyst support Z4 is similar to that of support Z1 in Example 1, except that the modified microporous-mesoporous ZSM-5 molecular sieve M4 prepared in this example is used.

[0090] (3) Catalyst preparation

[0091] The preparation method of catalyst A4 is similar to that of catalyst A1 in Example 1, the only difference being that the catalyst support obtained in this example is used in this example.

[0092] Example 5

[0093] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0094] The preparation method of the modified microporous-mesoporous ZSM-5 molecular sieve is the same as that in Example 4.

[0095] (2) Preparation of catalyst support

[0096] The preparation method of the catalyst support is similar to that in Example 1, except that in this example, 100g of modified microporous-mesoporous ZSM-5 molecular sieve M4, 4.0g of guar gum powder and 105g of binder N1 are weighed and added to a kneader for kneading, and then dried at 120℃ and calcined at 550℃ for 4 hours to obtain support Z5.

[0097] (3) Catalyst preparation

[0098] The preparation method of catalyst A5 is similar to that of Example 4, except that in this example, 5.6g of gallium nitrate, 7.9g of nickel nitrate, and 5.4g of lanthanum nitrate were weighed, dissolved in deionized water, stirred evenly to obtain a clear solution, and then diluted to 60ml with deionized water; 100g of support Z5 was weighed and impregnated with an equal volume, allowed to stand for 6 hours, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours to obtain catalyst A5.

[0099] Example 6

[0100] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0101] Weigh 120g of nano HZSM-5 molecular sieve and heat it at 500℃ for 2 hours. -1 Under the condition of hydrothermal aging for 3 hours, dealuded nano HZSM-5 molecular sieve S6 was obtained.

[0102] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S6, followed by 91g of hexadecyltrimethylammonium bromide, 20.4g of zinc acetate dihydrate, and 8.5g of thioacetylammonium. After stirring for 1h, solution S6 is obtained. Solution S6 is placed in a crystallization vessel and crystallized for the first time at 100℃ for 18h in a drying oven, followed by a second crystallization at 180℃ for 24h. The crystallized product is then filtered and washed with 0.1mol / L ammonium chloride solution until the pH of the product eluent is 8. The resulting filter cake is dried at 150℃ for 90min in a drying oven and calcined in a muffle furnace at 500℃ for 240min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M6 (i.e., modified ZSM-5 molecular sieve).

[0103] (2) Preparation of catalyst support

[0104] The preparation method of catalyst support Z6 is similar to that of support Z4 in Example 4, except that microporous-mesoporous ZSM-5 molecular sieve M6 is used in this example.

[0105] (3) Catalyst preparation

[0106] The preparation method of catalyst A6 is similar to that of catalyst A4 in Example 4, except that in this example, 4.3g of gallium nitrate, 6.1g of nickel nitrate, and 4.2g of lanthanum nitrate were weighed, dissolved in deionized water, stirred evenly to obtain a clear solution, and then diluted to 60ml with deionized water; 100g of support Z6 was weighed and impregnated with an equal volume, allowed to stand for 6 hours, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours to obtain catalyst A6.

[0107] Example 7

[0108] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0109] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0110] Weigh 16.8g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.3mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S7, followed by the sequential addition of 109g of hexadecyltrimethylammonium bromide, 20.2g of zinc acetate dihydrate, and 8.5g of thioacetylammonium. After stirring for 1h, solution S7 is obtained. Solution S7 is placed in a crystallization vessel and crystallized for the first time at 100℃ for 18h in a drying oven, followed by a second crystallization at 180℃ for 24h. The crystallized product is then filtered and washed with 0.5mol / L ammonium nitrate solution until the pH of the product eluent is 9. The resulting filter cake is dried at 150℃ for 90min in a drying oven and calcined in a muffle furnace at 550℃ for 240min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M7 (i.e., modified ZSM-5 molecular sieve).

[0111] (2) Preparation of catalyst support

[0112] The preparation method of catalyst support Z7 is similar to that of support Z6 in Example 6, the only difference being that the microporous-mesoporous ZSM-5 molecular sieve M7 prepared in this example is used.

[0113] (3) Catalyst preparation

[0114] The preparation method of catalyst A7 is similar to that of catalyst A6 in Example 6, except that the catalyst support Z7 prepared in this example is used.

[0115] Example 8

[0116] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0117] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0118] Weigh 8.4g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.15mol / L potassium hydroxide solution. Then, while stirring, slowly add this potassium hydroxide solution to 100g of the above-mentioned dealuded nano HZSM-5 molecular sieve S8, followed by the sequential addition of 109g of hexadecyltrimethylammonium bromide, 20.2g of zinc acetate dihydrate, and 16.8g of ammonium thiosulfate. After stirring for 1h, solution S8 is obtained. Solution S8 is placed in a crystallization vessel and crystallized for the first time at 120℃ for 16h in a drying oven, followed by a second crystallization at 180℃ for 20h. The crystallized product is then filtered and washed with 0.5mol / L ammonium chloride solution until the pH of the product eluent is 9. The resulting filter cake is dried at 120℃ for 120min in a drying oven and calcined in a muffle furnace at 550℃ for 240min to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M8 (i.e., modified ZSM-5 molecular sieve).

[0119] (2) Preparation of catalyst support

[0120] The preparation method of catalyst support Z8 is similar to that of support Z6 in Example 6, except that the microporous-mesoporous ZSM-5 molecular sieve M8 prepared in this example is used.

[0121] (3) Catalyst preparation

[0122] The preparation method of catalyst A8 is similar to that of catalyst A6 in Example 6, except that the catalyst support Z8 prepared in this example is used.

[0123] Example 9

[0124] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0125] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0126] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Add 100g of hydrothermally treated HZSM-5 molecular sieve S9 to a beaker, and slowly add the above potassium hydroxide solution while stirring. Then add 36.3g of hexadecyltrimethylammonium bromide, 20.2g of zinc acetate dihydrate, and 8.5g of thioacetylammonium in sequence. Stir for 1h to obtain solution A9. Place solution S9 in a crystallization vessel and crystallize for the first time at 120℃ for 16h in a drying oven, then raise the temperature to 180℃ for a second crystallization for 20h. Then filter the crystallization product and wash it with 0.5mol / L ammonium chloride solution until the pH of the product eluent is 8. The obtained filter cake is dried at 150℃ for 120min in a drying oven and calcined at 550℃ for 160min in a muffle furnace to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M9 (i.e., modified ZSM-5 molecular sieve).

[0127] (2) Preparation of catalyst support

[0128] The preparation method of catalyst support Z9 is similar to that of support Z6 in Example 6, except that the microporous-mesoporous ZSM-5 molecular sieve M9 prepared in this example is used.

[0129] (3) Catalyst preparation

[0130] The preparation method of catalyst A9 is similar to that of catalyst A6 in Example 6, except that the catalyst support Z9 prepared in this example is used.

[0131] Example 10

[0132] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0133] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0134] Weigh 5.6g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.1mol / L potassium hydroxide solution. Add 100g of hydrothermally treated HZSM-5 molecular sieve S10 to a beaker, and slowly add the above potassium hydroxide solution while stirring. Then add 72.7g of hexadecyltrimethylammonium bromide, 20.2g of zinc acetate dihydrate, and 16.8g of ammonium thiosulfate in sequence. After stirring for 1 hour, solution A10 is obtained. The other steps are the same as in Example 6 to obtain microporous-mesoporous ZSM-5 molecular sieve M10.

[0135] (2) Preparation of catalyst support

[0136] The preparation method of catalyst support Z10 is similar to that of support Z6 in Example 6, except that the microporous-mesoporous ZSM-5 molecular sieve M10 prepared in this example is used.

[0137] (3) Catalyst preparation

[0138] The preparation method of catalyst A10 is similar to that of catalyst A6 in Example 6, except that the catalyst support Z10 prepared in this example is used.

[0139] Example 11

[0140] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0141] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0142] Weigh 4.0g of sodium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a sodium hydroxide solution with a concentration of 0.1mol / L. Add 100g of hydrothermally treated HZSM-5 molecular sieve S11 to a beaker, and slowly add the above sodium hydroxide solution while stirring. Then add 63.8g of hexadecyltrimethylammonium chloride, 20.2g of zinc acetate dihydrate, and 6.9g of thioacetamide in sequence. After stirring for 1h, solution A11 is obtained. The other steps are the same as in Example 6 to obtain zinc in-situ modified microporous-mesoporous ZSM-5 molecular sieve.

[0143] Microporous-mesoporous ZSM-5 molecular sieve was mixed with 0.1 mol / L ammonium nitrate at a solid-liquid ratio of 1 g: 15 mL. Ammonium exchange was performed twice at 60 °C, with stirring for 120 min each time. The mixture was then filtered, washed with deionized water until neutral, dried at 150 °C for 120 min, and calcined in a muffle furnace at 500 °C for 240 min to obtain hydrogen-form microporous-mesoporous ZSM-5 molecular sieve M11.

[0144] (2) Preparation of catalyst support

[0145] The preparation method of catalyst support Z11 is similar to that of support Z6 in Example 6, except that the microporous-mesoporous ZSM-5 molecular sieve M11 prepared in this example is used.

[0146] (3) Catalyst preparation

[0147] The preparation method of catalyst A11 is similar to that of catalyst A6 in Example 6, except that the catalyst support Z11 prepared in this example is used.

[0148] Example 12

[0149] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0150] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 6.

[0151] Weigh 12g of sodium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a sodium hydroxide solution with a concentration of 0.3mol / L. Add 100g of hydrothermally treated HZSM-5 molecular sieve S12 to a beaker, and slowly add the above sodium hydroxide solution while stirring. Then add 95.7g of hexadecyltrimethylammonium chloride, 20.2g of zinc acetate dihydrate, and 10.8g of thioacetamide in sequence. After stirring for 1h, solution A12 is obtained. The other steps are the same as in Example 6 to obtain zinc in-situ modified microporous-mesoporous ZSM-5 molecular sieve.

[0152] Microporous-mesoporous ZSM-5 molecular sieve was mixed with 0.5 mol / L ammonium chloride at a solid-liquid ratio of 1 g: 10 mL. Ammonium exchange was performed twice at 60 °C, with stirring for 120 min each time. The mixture was then filtered, washed with deionized water until neutral, dried at 150 °C for 120 min, and calcined in a muffle furnace at 500 °C for 240 min to obtain hydrogen-form microporous-mesoporous ZSM-5 molecular sieve M12.

[0153] (2) Preparation of catalyst support

[0154] The preparation method of catalyst support Z12 is similar to that of support Z11 in Example 11, except that the microporous-mesoporous ZSM-5 molecular sieve M12 prepared in this example is used.

[0155] (3) Catalyst preparation

[0156] The preparation method of catalyst A12 is similar to that of catalyst A11 in Example 11, except that the catalyst support Z12 prepared in this example is used.

[0157] Comparative Example 1

[0158] (1) Preparation of modified ZSM-5 molecular sieve

[0159] Weigh 120g of nano HZSM-5 molecular sieve and heat it at 550℃ for 3 hours. -1 Modified ZSM-5 molecular sieve was obtained by hydrothermal aging treatment for 3 hours.

[0160] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0161] (3) Preparation of catalyst: Weigh 3.4g gallium nitrate, 4.8g nickel nitrate, 13.5g zinc nitrate hexahydrate and 3.3g lanthanum nitrate and dissolve them in deionized water. Stir evenly to obtain a clear solution. Then, dilute the solution with deionized water to 60ml to obtain an impregnation solution. Weigh 100g of the catalyst support prepared in step (2) and impregnate it with the impregnation solution in equal volume. After standing for 6 hours, dry at 120℃ for 4 hours and calcine at 500℃ for 4 hours to obtain catalyst D1.

[0162] Comparative Example 2

[0163] (1) Preparation of modified ZSM-5 molecular sieve: Similar to Example 1, except that no thiolated compound was added in this comparative example.

[0164] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0165] (3) Catalyst preparation: Similar to Example 1, except that the catalyst support prepared in this comparative example was used. Catalyst D2 was finally obtained.

[0166] Comparative Example 3

[0167] (1) Preparation of modified ZSM-5 molecular sieve: Similar to Example 1, except that cetyltrimethylammonium bromide was not added in this comparative example.

[0168] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0169] (3) Catalyst preparation: Similar to Example 1, except that the catalyst support prepared in this comparative example was used. Finally, catalyst D3 was obtained.

[0170] The catalysts prepared in the above embodiments and comparative examples were subjected to physicochemical property tests, and the specific results are shown in Table 1 below. The total specific surface area, external specific surface area, total pore volume, and mesopore volume were tested according to GB / T5816; the oxide content was tested using X-ray fluorescence spectrometry; and the L / B ratio was calculated based on the total amount of Li acid and total amount of Beta acid determined by the pyridine IR method. Mesopore ratio = mesopore volume / total pore volume × 100%.

[0171] Table 1 Physicochemical properties of the catalyst

[0172]

[0173]

[0174] The catalysts prepared in the above embodiments and comparative examples were respectively loaded into a 100ml hydrogenation evaluation device for performance evaluation. The catalysts were subjected to wet sulfidation, with carbon disulfide as the sulfiding agent and refined naphtha as the sulfiding oil. Hydrogen was passed through once. The sulfidation conditions were as follows: sulfiding oil was introduced at 150°C and held for 2 hours; the temperature was increased to 230°C at a rate of 20°C / h and held for 8 hours; the temperature was further increased to 320°C at a rate of 20°C / h and held for 6 hours; the volume hourly space velocity was 2 h⁻¹. -1 The hydrogen-to-oil ratio is 200:1, and the pressure is 2.0 MPa. After sulfidation, the temperature is lowered to 230°C, and then catalytic heavy gasoline feedstock is introduced.

[0175] Hydrogenation reaction conditions: reaction temperature 385℃, reaction pressure 2.0 MPa, hydrogen-to-oil volume ratio 200:1, volume hourly space velocity 1.5 h⁻¹. -1 The specific performance evaluation results are shown in the table below.

[0176] Table 2 Evaluation results of olefin aromatization of the catalyst

[0177]

[0178]

[0179] As shown in Tables 1 and 2, the low-carbon hydrocarbon aromatization catalyst prepared by the modified ZSM-5 molecular sieve using the method provided in this invention exhibits significantly better aromatization activity and crack inhibition activity than the catalyst prepared in the comparative example during the olefin aromatization reaction. This comprehensively solves the problems of insufficient olefin reduction, low aromatization activity, and low gasoline product yield in the existing technology for upgrading gasoline to the China VIB standard. Specifically, Examples 1 and 2 mainly achieved physical control of the catalyst's acid content and mesoporous structure by adjusting the molecular sieve addition ratio, thus increasing the mesoporous ratio of alumina. Examples 1, 3, 4, 5, and 6 mainly significantly reduced the strong acid content by adjusting the addition content of zinc, nickel, lanthanum, and gallium. The reaction of zinc with the aluminum framework generates a moderately strong L-acid (ZnOH+) that facilitates the aromatization reaction, effectively increasing the catalyst's L / B ratio and the proportion of moderately strong L-acid. This achieves the control of the catalyst's aromatization and cracking activities, solving the problems of low aromatization activity and low gasoline product yield. Issues such as low yield were addressed. Examples 6, 7, and 8 primarily controlled the concentration of potassium hydroxide solution, utilizing potassium hydroxide as both an alkali source and a precursor for modified metal additives. This effectively regulated the catalyst's pore structure and acid distribution, increasing the mesoporous ratio, promoting the diffusion of raw material and product molecules within the pores, helping to suppress side reactions such as the formation of polycyclic aromatic hydrocarbons, and improving the catalyst's aromatization activity and reducing the product's dry point shift. Examples 6, 9, and 10 primarily controlled the amount of mesoporous template agent to modulate the degree of further crystallization of non-framework aluminum and silicon within the system. Effective control of the crystallinity and specific surface area of ​​ZSM-5 molecular sieves was achieved, promoting the olefin aromatization activity of the catalyst. Examples 10, 11, and 12 mainly controlled the crystallinity, specific surface area, and acid distribution of ZSM-5 molecular sieves by replacing the alkali source with sodium hydroxide, the template agent with hexadecyltrimethylammonium chloride, and the thiocarboxylic acid with thioacetamide, thus promoting the olefin aromatization activity of the catalyst. Compared with Example 1, Comparative Example 1 lacked the molecular sieve alkali modification and hydrothermal crystallization process, resulting in variations in catalyst specific surface area, mesopore ratio, and... The L / B ratio was significantly reduced, the olefin aromatization activity of the catalyst was significantly reduced, while the cracking activity was significantly increased. Compared with Example 1, no thiolated compounds were introduced during the alkali modification and hydrothermal crystallization process of the molecular sieve in Comparative Example 2. The mesoporous ratio and L / B of the prepared catalyst were reduced, and it existed in the form of zinc oxide. It was impossible to achieve in-situ modification of strong acid on the surface of the molecular sieve. The amount of strong acid and the amount of acid on the outer surface were high, which easily led to the loss of the modifying agent during the use of the catalyst. In addition, the cracking activity of the catalyst was high in the early stage of the reaction, and the side reactions such as the generation of polycyclic aromatic hydrocarbons were violent, resulting in a serious delay in the dry point.Compared with Example 1, Comparative Example 3 did not introduce hexadecyltrimethylammonium bromide during the hydrothermal crystallization process. The specific surface area and mesopore volume of the resulting molecular sieve were reduced. Some skeleton aluminum or silicon remained in the molecular sieve channels, making it impossible to achieve fine control over the morphology of the molecular sieve. Furthermore, it was not easy to generate mesopores, which affected the acid distribution of the molecular sieve and was not conducive to the performance of low-temperature aromatization activity. Meanwhile, side reactions such as cracking were aggravated, resulting in a decrease in the yield of gasoline products.

[0180] Of course, the present invention may have other embodiments and variations. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and variations according to the present invention, but these corresponding changes and variations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing modified ZSM-5 molecular sieve, characterized in that, Includes the following steps: Nano HZSM-5 molecular sieves are subjected to hydrothermal aging treatment to obtain dealuded nano HZSM-5 molecular sieves; An inorganic alkaline solution, a zinc-containing compound, a thiolated compound, and a mesoporous template agent were added to the dealuded nano-HZSM-5 molecular sieve for hydrothermal crystallization. After drying and calcination, the modified ZSM-5 molecular sieve was obtained.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the zinc-containing compound to the thiolated compound is 0.6 to 1.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the inorganic alkali in the inorganic alkali solution to the mesoporous template agent is 0.3 to 1.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the dealuminated nano HZSM-5 molecular sieve, the thiolated compound, and the mesoporous template agent is 1:(0.06-0.36):(0.36-1.1).

5. The preparation method according to claim 1, characterized in that, The hydrothermal aging treatment is performed at a temperature of 400–600°C and a mass hourly space velocity (HHSV) of 0.5–3 h⁻¹. -1 The time is 1 to 5 hours.

6. The preparation method according to claim 1, characterized in that, The hydrothermal crystallization is a programmed crystallization process; the programmed crystallization includes hydrothermal crystallization at 100-120°C for 12-24 hours, followed by hydrothermal crystallization at 160-200°C for 12-24 hours.

7. The preparation method according to claim 1, characterized in that, The drying temperature is 120–180°C, and the time is 60–180 min; The roasting temperature is 450–550°C, and the time is 240–360 min.

8. The preparation method according to claim 1, characterized in that, The thio compound is selected from thioacetamide or thiosulfate; The mesoporous template agent is selected from hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; The inorganic alkaline solution is selected from inorganic sodium salt solution or inorganic potassium salt solution, wherein the inorganic potassium salt solution is selected from at least one of potassium carbonate solution, potassium hydroxide solution, and potassium bicarbonate solution; the inorganic sodium salt solution is selected from at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate; preferably, the concentration of the inorganic alkaline solution is 0.1–0.3 mol / L. The zinc-containing compound is selected from at least one of zinc acetate dihydrate, zinc nitrate, and zinc sulfate.

9. The preparation method according to claim 8, characterized in that, When the inorganic alkaline solution is selected from an inorganic sodium salt solution, the process further includes ammonium exchange of the modified ZSM-5 molecular sieve, washing until neutral, secondary drying, and secondary calcination.

10. The preparation method according to claim 9, characterized in that, The ammonium solution used in the ammonium exchange step is selected from ammonium chloride solution and / or ammonium nitrate solution; preferably, The secondary drying temperature is 120–180°C, and the time is 60–180 min; The secondary roasting temperature is 450–550℃, and the time is 240–360 min.

11. The preparation method according to claim 8, characterized in that, When the inorganic alkaline solution is selected from an inorganic potassium salt solution, before the drying, the product of the hydrothermal crystallization is further separated and washed with ammonium chloride solution or ammonium nitrate solution until the pH is 8-9.

12. A modified ZSM-5 molecular sieve prepared by the method of any one of claims 1-11.

13. The application of the modified ZSM-5 molecular sieve prepared by the method of any one of claims 1-11 in the preparation of catalysts.

14. A method for preparing a low-carbon hydrocarbon aromatization catalyst support, characterized in that, The process includes the following steps: mixing modified ZSM-5 molecular sieve with binder and extrusion aid, followed by drying and calcination to obtain a low-carbon hydrocarbon aromatization catalyst support; The modified ZSM-5 molecular sieve is prepared by the method described in any one of claims 1-11.

15. A method for preparing a low-carbon hydrocarbon aromatization catalyst, characterized in that, Includes the following steps: The catalyst support was loaded with metal additives by impregnation, and then dried and calcined to obtain the low-carbon hydrocarbon aromatization catalyst. The catalyst support is selected from the low-carbon hydrocarbon aromatization catalyst support prepared by the method described in claim 14. The metal additive is selected from at least one of Group VIII metal salts, Group IIIA metal salts, and Group IIIB metal salts.

16. A low-carbon hydrocarbon aromatization catalyst prepared by the method of claim 15, characterized in that, The catalyst comprises a support and an active component. The support includes nano-ZSM-5 molecular sieve and alumina. The active component includes zinc, Group IIIA metals, Group VIII metals, and Group IIIB metals. Preferably, the low-carbon hydrocarbon aromatization catalyst also includes potassium oxide.

17. The low-carbon hydrocarbon aromatization catalyst according to claim 16, characterized in that, The low-carbon hydrocarbon aromatization catalyst has a microporous-mesoporous structure, a total acidity of 0.10–0.25 mmol / g, a strong Brønsted acidity of 0.02–0.1 mmol / g, and an L / B ratio of 2–6.

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