Microporous-mesoporous modified ZSM-5 molecular sieve as well as preparation method and application thereof

Abstract

The preparation method comprises the following steps: carrying out alkali treatment by taking a nano ZSM-5 molecular sieve subjected to hydrothermal treatment as a parent and potassium hydroxide or sodium hydroxide as an alkali source, then adding a mesoporous template agent, regulating the pH value to a certain range by using an alkaline reagent, and carrying out hydrothermal reaction to obtain the microporous-mesoporous modified ZSM-5 molecular sieve. And introducing a zinc compound and a thio compound in situ. Meanwhile, in the process, in order to promote the action of zinc and framework aluminum, a proper complexing agent is introduced to form a stable complex with a zinc compound to change the coordination environment of zinc ions, and then the zinc ions react with a thio compound to promote the action of zinc and framework aluminum to generate medium-strong L acid (ZnOH +), so that the low-temperature aromatization activity and shape selectivity of the catalyst are effectively improved, and the catalyst has high catalytic activity. The product distribution is improved, and the carbon deposition resistance of the catalyst is enhanced.

Description

Technical Field

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

[0002] 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, and have been industrially applied, especially in the aromatization of low-carbon hydrocarbons. 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, which is conducive to the occurrence of side reactions such as cracking and the formation of polycyclic aromatic hydrocarbons. Especially in the aromatization of gasoline, the low proportion of mesopores in the catalyst and the excessively high amount of strong acid on the surface lead to poor aromatization selectivity, easy coking and deactivation, affecting the long-term life of the catalyst and product distribution.

[0003] Acid centers, as the catalytically active sites in aromatization reactions, are crucial for achieving appropriate aromatization. While increasing the reaction temperature favors aromatization, it also promotes side reactions such as cracking and cyclization, accelerating catalyst deactivation. Therefore, developing a low-temperature-suitable aromatization catalyst by regulating the synergistic effect of the catalyst's metal active centers and acid centers, and optimizing the molecular sieve pore structure, is key to addressing the current challenges of poor aromatization selectivity, easy coking and deactivation, and the resulting instability in long-term stable operation.

[0004] Currently, post-treatment and template methods are mainly used to expand the pores of ZSM-5 molecular sieves. However, these methods tend to reduce the crystallinity and acidity of the molecular sieves, and the removed non-framework aluminum or silicon remains in the sieve channels, affecting the acid distribution and hindering the low-temperature aromatization activity. Furthermore, methods such as impregnation and ion exchange to regulate the synergistic effect between the catalyst's metal active centers and acid centers often lead to the accumulation of metal promoters on the support surface, clogging the catalyst channels and affecting the accessibility of acidic and metal active centers within the channels. For example, Chinese patent document CN106215973A discloses a method for preparing a modified ZSM-5 molecular sieve catalyst. Specifically, ZSM-5 molecular sieve, aluminum source, template agent, structural aid, additive, alkali, and water are mixed and stirred to prepare a precursor aqueous solution. This solution is then crystallized, subjected to solid-liquid separation, and calcined to obtain modified molecular sieve powder. This powder is then mixed with an ammonium salt solution, stirred, filtered, and repeatedly mixed with the ammonium salt solution, filtered, and calcined to obtain a hydrogen-form ZSM-5 molecular sieve. Finally, this sieve is mixed with a metal precursor solution, dried, and calcined to obtain an aromatization catalyst. Although this catalyst exhibits high aromatic selectivity, it is prone to coking and deactivation, and is not suitable for low-temperature aromatization reactions. Chinese patent document CN107876082A discloses a method for post-treatment of ZSM-5 molecular sieves. This method involves alkali treatment of the ZSM-5 molecular sieve with an organic alkaline solution followed by crystallization. This process expands the pores of the molecular sieve while simultaneously repairing its framework structure, improving its crystallinity and producing a hierarchical molecular sieve with micropores, mesopores, and macropores. However, the catalysts prepared using this molecular sieve exhibit poor selectivity for aromatization and are not suitable for low-temperature aromatization reactions. Summary of the Invention

[0005] In view of this, the present invention provides a microporous-mesoporous modified ZSM-5 molecular sieve, its preparation method, and its application. First, hydrothermally treated nano-ZSM-5 molecular sieve is used as the parent material, and alkali treatment is performed using potassium hydroxide or sodium hydroxide as the alkali source. Then, a mesoporous template agent is added, and the pH value is adjusted to a certain range using an alkaline reagent. Next, zinc compounds and thio compounds are introduced in situ. Simultaneously, to promote the interaction between zinc and framework aluminum, a suitable complexing agent is introduced to form a stable complex with the zinc compound, thereby altering the coordination environment of zinc ions. This complex then reacts with the thio compound, promoting the interaction between zinc and framework aluminum to generate a moderately strong L-acid (ZnOH+). This effectively improves the low-temperature aromatization activity and shape selectivity of the catalyst, improves product distribution, and enhances the catalyst's resistance to carbon deposition.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing microporous-mesoporous modified ZSM-5 molecular sieve includes the following steps:

[0008] Nano HZSM-5 molecular sieves are subjected to hydrothermal aging treatment to obtain dealuded nano HZSM-5 molecular sieves;

[0009] The dealuded nano-HZSM-5 molecular sieve was added to an inorganic alkaline solution. After adding a mesoporous template agent and controlling the pH of the system to 13-14, a zinc-containing compound, a complexing agent, and a thiolated compound were added. After hydrothermal crystallization, filtration, drying, and calcination, a microporous-mesoporous modified ZSM-5 molecular sieve was obtained.

[0010] In one alternative embodiment, the zinc-containing compound and the complexing agent are added first, and after mixing, the thiolated compound is added.

[0011] In one alternative embodiment, the molar ratio of the complexing agent to the zinc-containing compound is 0.6 to 2.5.

[0012] In one alternative embodiment, the molar ratio of the zinc-containing compound to the thio compound is 0.6 to 1.

[0013] In one optional embodiment, the molar ratio of the inorganic alkali in the inorganic alkali solution to the mesoporous template agent is 0.3 to 1.

[0014] In one alternative embodiment, the molar ratio of the zinc-containing compound to the thio compound is 0.6 to 1.

[0015] In one optional embodiment, the mass ratio of the dealuded nano HZSM-5 molecular sieve, the zinc-containing compound, and the mesoporous template agent is 1:(0.18-0.40):(0.7-1.1).

[0016] In one alternative embodiment, after adding the mesoporous template agent, the pH of the system is controlled with an alkaline reagent selected from urea and / or ammonia.

[0017] 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.

[0018] 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.

[0019] In one optional embodiment, the drying temperature is 120–180°C and the time is 60–180 min.

[0020] In one optional embodiment, the calcination temperature is 450–550°C and the time is 240–360 min.

[0021] In one alternative embodiment, the complexing agent is selected from at least one of ammonium dihydrogen phosphate and ethylenediamine or EDTA.

[0022] In one alternative embodiment, the thio compound is selected from thioacetamide and / or ammonium thiosulfate.

[0023] In one alternative embodiment, the mesoporous template agent is selected from hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride.

[0024] 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.

[0025] In one alternative embodiment, the zinc-containing compound is selected from at least one of zinc acetate dihydrate, zinc nitrate, and zinc sulfate.

[0026] 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 and / or ammonium nitrate; 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.

[0027] In one optional embodiment, the ammonium exchange time is 0.5 to 4 hours.

[0028] In one optional embodiment, the secondary drying temperature is 120–180°C and the time is 60–180 min.

[0029] In one optional embodiment, the secondary calcination temperature is 450–550°C and the time is 240–360 min.

[0030] In an optional embodiment, when the inorganic alkaline solution is selected from an inorganic potassium salt solution, the process further includes separating the hydrothermal crystallization product and washing it with ammonium chloride or ammonium nitrate solution until the pH reaches 8-9 before drying. Potassium salts can react with silicon on the molecular sieve framework, causing some silicon to detach from the framework and form a mesoporous structure. This facilitates molecular diffusion within the pores and improves mass transfer efficiency in the catalytic reaction. Simultaneously, potassium salts can also act as a modifying agent to regulate the acid distribution of the molecular sieve, reduce acid strength, and decrease the occurrence of side reactions such as cracking and aromatic alkylation.

[0031] The present invention also provides a method for preparing microporous-mesoporous modified ZSM-5 molecular sieves as described above, resulting in microporous-mesoporous modified ZSM-5 molecular sieves.

[0032] The microporous-mesoporous modified ZSM-5 molecular sieve prepared by the above-mentioned method provided by the present invention can be used in the preparation of catalysts.

[0033] 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;

[0034] The modified ZSM-5 molecular sieve is prepared by the above-mentioned method for preparing microporous-mesoporous modified ZSM-5 molecular sieve.

[0035] In one alternative embodiment, the extrusion aid is selected from at least one of guar gum powder, starch, and citric acid.

[0036] In one optional embodiment, the binder is selected from a gel formed by mixing boehmite, nitric acid, and water; the mass ratio of the dry basis of the boehmite to nitric acid and water is 1:(0.1-0.3):(2.2-3.0). After the boehmite, nitric acid, and water are mixed evenly to form a gel, it is left to stand for 24 hours before use.

[0037] 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.

[0038] In one alternative 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).

[0039] This invention also provides a method for preparing a low-carbon hydrocarbon aromatization catalyst, comprising the following steps:

[0040] The catalyst support is impregnated (e.g., with an equal volume impregnation) with a loaded metal additive, and then dried and calcined to obtain the low-carbon hydrocarbon aromatization catalyst.

[0041] The catalyst support is selected from the low-carbon hydrocarbon aromatization catalyst support prepared by the above-mentioned method.

[0042] The metal additive is selected from at least one of Group VIII metal salts, Group IIIA metal salts, and Group IIIB metal salts.

[0043] 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.

[0044] The present invention also provides a low-carbon hydrocarbon aromatization catalyst prepared by the above-mentioned method, comprising a support and an active component. 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; based on 100% by mass of the low-carbon hydrocarbon aromatization catalyst, the content of nano-ZSM-5 molecular sieve is 60% to 80%, the content of the active component as oxide is 6.5% to 18.5%, and the balance is alumina;

[0045] Preferably, based on the mass of the low-carbon hydrocarbon aromatization catalyst as 100%, the active component contains 3-9% zinc oxide, 1-2% Group IIIA metals, 1-2% Group VIII metals, and 1-2% Group IIIB metals.

[0046] In an optional embodiment, the low-carbon hydrocarbon aromatization catalyst further includes potassium oxide and / or phosphorus oxide, wherein the potassium oxide content is 0.7% to 2.5% and the phosphorus oxide content is 0.5% to 1%.

[0047] In one optional embodiment, the low-carbon hydrocarbon aromatization catalyst has a microporous to mesoporous structure, the total acid content of the low-carbon hydrocarbon aromatization catalyst is 0.10 to 0.30 mmol / g, the strong Brønsted acid content is 0.01 to 0.08 mmol / g, the proportion of medium-strong acids is ≥30%, and the L / B ratio is 2 to 8.

[0048] In one optional embodiment, the specific surface area of ​​the low-carbon hydrocarbon aromatization catalyst is 200–400 m². 2 / g, total pore volume 0.2~0.4ml / g, external specific surface area 100~200m 2 / g, mesoporous pore volume 0.1~0.28ml / g, mesoporous pore volume ratio ≥60%.

[0049] 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 300–360 °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.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] To address the problems of poor aromatization selectivity, easy coking and deactivation, and poor long-term stability of catalysts prepared from ZSM-5 molecular sieves under low-temperature conditions, the inventors introduced zinc compounds and thio compounds in situ through a combination of alkali treatment and hydrothermal crystallization. This simultaneously achieved pore expansion and effective control of the acid and metal active centers of the ZSM-5 molecular sieve. However, due to the influence of factors such as pH value, metal coordination environment, and molecular sieve pore structure, the modified molecular sieve prepared by the above method has problems such as low zinc introduction and low utilization rate. This may be because the presence of thio compounds is not conducive to the interaction between zinc and framework aluminum. As a result, the increase of medium-strong L-acid (ZnOH+) which is conducive to low-temperature aromatization reaction is small. Therefore, it is not conducive to the low-temperature aromatization activity and shape selectivity of the catalyst, and it is easy to cause catalyst coking, which is not conducive to long-term stable operation.

[0052] To address the aforementioned problems, the inventors further discovered that by adjusting and controlling the feeding sequence and pH of each material, combined with the introduction of a complexing agent, the low-temperature aromatization activity and shape selectivity can be significantly improved, and the problem of catalyst coking can be overcome. Specifically, the method for preparing microporous-mesoporous modified ZSM-5 molecular sieve provided by this invention, by controlling the pH range of the in-situ introduction of zinc compounds and thio compounds, provides a reaction environment that promotes the combination of zinc and framework aluminum to generate a moderately strong L-acid (ZnOH+) that is conducive to the aromatization reaction. This solves the problems that zinc is difficult to combine with framework aluminum at too low pH, and zinc easily precipitates on the surface of the molecular sieve and blocks the pores at too high pH, ​​as well as the difficulty in reacting with thio compounds. This effectively improves the low-temperature catalytic activity and shape selectivity of the catalyst for aromatization.

[0053] Meanwhile, in the process of in-situ introduction of zinc-containing compounds and thiolated compounds, a suitable complexing agent is introduced to form a stable complex with the zinc-containing compound, thereby changing the coordination environment of zinc ions. This complex then reacts with the thiolated compound, promoting the interaction of zinc with skeletal aluminum to generate medium-strong L-acids (ZnOH+) and zinc sulfide. This solves the problems of low zinc introduction, low utilization rate, and the presence of thiolated compounds hindering the interaction between zinc and skeletal aluminum in conventional methods. Furthermore, the formation of zinc sulfide during the synthesis process avoids the problems of low sulfidation degree, uneven sulfide distribution, and weak metal-sulfide bonding that occur in existing technologies where catalysts are prepared before sulfidation. This reduces metal loss during catalyst use and improves catalyst stability. Simultaneously, by utilizing ammonium dihydrogen phosphate as both a complexing agent and a modifying agent, the amount of strong acid is reduced while the amount of medium-strong acid is increased, achieving comprehensive control over the acid distribution of the molecular sieve. This effectively improves the low-temperature aromatization activity and shape selectivity of the catalyst, improves product distribution, and enhances the catalyst's resistance to carbon deposition. Detailed Implementation

[0054] 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.

[0055] 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.

[0056] Example 1

[0057] (1) Preparation of modified ZSM-5 molecular sieve

[0058] Weigh 150g of nano HZSM-5 molecular sieve and heat it at 500℃ for 3 hours.-1 Hydrothermal aging treatment was carried out under the conditions for 4 hours to obtain dealuded nano HZSM-5 molecular sieve S1.

[0059] 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 100g of the above-mentioned dealuminized nano-HZSM-5 molecular sieve S1 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 100g of hexadecyltrimethylammonium bromide and adjust the pH of the system to 13.5 with 25wt% ammonia water. Then add 18.3g of zinc acetate dihydrate, 2.0g of ammonium dihydrogen phosphate, 2.1g of ethylenediamine, and 12.1g of sulfur in sequence. Ammonium sulfate was added and stirred for 1 hour to obtain solution S1. Solution S1 was placed in a crystallization vessel and crystallized for the first time at 100℃ for 24 hours in a drying oven, followed by a second crystallization at 180℃ for 24 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium chloride solution until the pH of the product eluent was 9. The resulting filter cake was dried at 150℃ for 120 minutes in a drying oven and calcined in a muffle furnace at 500℃ for 360 minutes to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M1 (i.e., modified ZSM-5 molecular sieve).

[0060] (2) Preparation of catalyst support

[0061] Weigh 139g of boehmite (72% dry basis) and add it to a kneader. Weigh 15g of nitric acid and add it to 240g 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.

[0062] Weigh 100g of modified microporous-mesoporous ZSM-5 molecular sieve M1, 3.75g of guar gum powder, and 99g 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.

[0063] (3) Catalyst preparation

[0064] 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 59ml 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.

[0065] Example 2

[0066] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0067] Weigh 150g of nano HZSM-5 molecular sieve and heat it at 400℃ for 3 hours. -1 Under the condition of hydrothermal aging for 5 hours, dealuded nano HZSM-5 molecular sieve S2 was obtained.

[0068] 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 100g of the above-mentioned dealuminized nano-HZSM-5 molecular sieve S2 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 100g of hexadecyltrimethylammonium bromide and adjust the pH of the system to 13.7 with 25wt% ammonia water. Then add 18.3g of zinc acetate dihydrate, 2.0g of ammonium dihydrogen phosphate, 2.1g of ethylenediamine, and 12.1g of sulfur in sequence. Ammonium sulfate was added and stirred for 1 hour to obtain solution S2. Solution S2 was placed in a crystallization vessel and crystallized for the first time at 100℃ for 24 hours in a drying oven, followed by a second crystallization at 180℃ for 24 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium chloride solution until the pH of the product eluent was 9. The resulting filter cake was dried at 150℃ for 120 minutes in a drying oven and calcined in a muffle furnace at 520℃ for 300 minutes to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M2 (i.e., modified ZSM-5 molecular sieve).

[0069] (2) Preparation of catalyst support

[0070] The preparation method of the catalyst support is similar to that of Example 1, except that in this example, 100g of modified microporous-mesoporous ZSM-5 molecular sieve M1, 3.8g of guar gum powder and 257g of binder N1 are weighed and added to a kneader for kneading, and then dried at 120℃ and calcined at 500℃ for 5 hours to obtain support Z2.

[0071] (3) Catalyst preparation

[0072] The catalyst preparation method is similar to that in Example 1, except that: in this example, deionized water is used to make up to 62 ml, and the support Z2 obtained in this example is used to finally obtain catalyst A2.

[0073] Example 3

[0074] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0075] Weigh 150g of nano-HZSM-5 molecular sieve and heat it at 550℃ for 0.5h. -1 Hydrothermal aging treatment was carried out for 5 hours under the specified conditions to obtain dealuded nano HZSM-5 molecular sieve S3.

[0076] Weigh 15.7g of potassium hydroxide and add it to 1000ml of water, stirring until dissolved to prepare a 0.28mol / L potassium hydroxide solution. Then, while stirring, slowly add 100g of the above-mentioned dealuminized nano-HZSM-5 molecular sieve S3 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 102g of hexadecyltrimethylammonium bromide and adjust the pH of the system to 14.0 with 25wt% ammonia water. Then add 40.0g of zinc acetate dihydrate, 2.8g of ammonium dihydrogen phosphate, 30g of ethylenediamine, and 31.4g of... Ammonium thiosulfate was stirred for 1 hour to obtain solution S3. Solution S3 was placed in a crystallization vessel and crystallized for the first time at 120°C for 18 hours in a drying oven, followed by a second crystallization at 170°C for 16 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium nitrate solution until the pH of the product eluent was 8. The resulting filter cake was dried at 180°C for 70 minutes in a drying oven and calcined in a muffle furnace at 450°C for 320 minutes to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M3 (i.e., modified ZSM-5 molecular sieve).

[0077] (2) Preparation of catalyst support

[0078] The preparation method of catalyst support Z3 is similar to that of Example 1, except that the modified microporous-mesoporous ZSM-5 molecular sieve M3 prepared in this example is used to finally obtain catalyst support Z3.

[0079] (3) Catalyst preparation

[0080] 5.6g gallium nitrate, 7.9g nickel nitrate and 5.4g lanthanum nitrate were weighed and dissolved in deionized water. After stirring evenly, a clear solution was obtained. The solution was then diluted to 59ml with deionized water to obtain an impregnation solution. 100g of support Z3 was weighed and impregnated with the impregnation solution in an equal volume. After standing for 6 hours, the solution was dried at 120℃ for 4 hours and calcined at 500℃ for 4 hours to obtain catalyst A3.

[0081] Example 4

[0082] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0083] Weigh 150g of nano HZSM-5 molecular sieve and heat it at 600℃ for 2 hours. -1 Hydrothermal aging treatment was carried out for 1.5 hours under the specified conditions to obtain dealuded nano HZSM-5 molecular sieve S4.

[0084] 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 100g of the above-mentioned dealuminized nano-HZSM-5 molecular sieve S4 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 80g of hexadecyltrimethylammonium bromide and adjust the pH of the system to 14.0 with 25wt% ammonia water. Then add 35.1g of zinc nitrate hexahydrate, 2.0g of ammonium dihydrogen phosphate, 7.9g of ethylenediamine, and 19.9g of sulfur in sequence. Ammonium sulfate was added and stirred for 1 hour to obtain solution S4. Solution S4 was placed in a crystallization vessel and crystallized for the first time at 110℃ for 18 hours in a drying oven, and then the temperature was raised to 200℃ for the second crystallization for 12 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium chloride solution until the pH of the product eluent was 9. The resulting filter cake was dried at 140℃ for 180 minutes in a drying oven and calcined at 450℃ for 280 minutes in a muffle furnace to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M4 (i.e., modified ZSM-5 molecular sieve).

[0085] (2) Preparation of catalyst support

[0086] 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 is used in this example.

[0087] (3) Catalyst preparation

[0088] The preparation method of catalyst A4 is similar to that of catalyst A1 in Example 1, except that the catalyst support Z4 prepared in this example is used.

[0089] Example 5

[0090] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0091] Weigh 150g 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 S5.

[0092] 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 100g of the above-mentioned dealuminized nano-HZSM-5 molecular sieve S5 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 95.7g of hexadecyltrimethylammonium chloride and adjust the pH of the system to 13.8 with 25wt% ammonia water. Then add 25.9g of zinc acetate dihydrate, 2.0g of ammonium dihydrogen phosphate, 39.9g of EDTA, and 10.1g of... Thioacetylammonium was stirred for 1 hour to obtain solution S5. Solution S5 was placed in a crystallization vessel and crystallized for the first time at 100℃ for 24 hours in a drying oven, followed by a second crystallization at 170℃ for 24 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium chloride solution until the pH of the product eluent was 9. The resulting filter cake was dried at 120℃ for 120 minutes in a drying oven and calcined in a muffle furnace at 550℃ for 240 minutes to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve M5 (i.e., modified ZSM-5 molecular sieve).

[0093] (2) Preparation of catalyst support

[0094] The preparation method of catalyst support Z5 is similar to that of support Z4 in Example 4, except that the modified microporous-mesoporous ZSM-5 molecular sieve M5 prepared in this example is used.

[0095] (3) Catalyst preparation

[0096] The preparation method of catalyst A5 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 are weighed, dissolved in deionized water, stirred evenly to obtain a clear solution, and then diluted to 59ml with deionized water; 100g of support Z6 is weighed and impregnated with an equal volume, left to stand for 6 hours, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours to obtain catalyst A5.

[0097] Example 6

[0098] (1) Modified microporous-mesoporous ZSM-5 molecular sieve

[0099] The hydrothermal treatment method for nano HZSM-5 molecular sieves is the same as in Example 4.

[0100] 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. Then, while stirring, slowly add 100g of the above-mentioned dealuminated nano HZSM-5 molecular sieve to the prepared sodium hydroxide solution and stir for 1h. Then add 70g of hexadecyltrimethylammonium chloride and adjust the pH of the system to 13.5 with 25wt% ammonia water. Then add 19.4g of zinc acetate dihydrate, 7.9g of ethylenediamine, and 10.1g of thioacetamide in sequence, and stir for 1h to obtain solution A6. The other steps are the same as in Example 4 to obtain zinc in-situ modified microporous-mesoporous ZSM-5 molecular sieve.

[0101] Zinc-modified 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. The mixture underwent two ammonium exchange processes at 60 °C, with stirring for 150 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 M6.

[0102] (2) Preparation of catalyst support

[0103] The preparation method of catalyst support Z6 is similar to that of support Z4 in Example 4, except that the hydrogen-type microporous-mesoporous ZSM-5 molecular sieve M6 prepared in this example is used.

[0104] (3) Catalyst preparation

[0105] The preparation method of catalyst A6 is similar to that of catalyst A4 in Example 4, except that the catalyst support Z6 prepared in this example is used.

[0106] Comparative Example 1

[0107] (1) Preparation of modified ZSM-5 molecular sieve

[0108] 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.

[0109] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0110] (3) Preparation of catalyst: 3.4g gallium nitrate, 4.8g nickel nitrate, 13.5g zinc nitrate hexahydrate and 3.3g lanthanum nitrate were weighed and dissolved in deionized water. After stirring evenly and obtaining a clear solution, the volume was adjusted to 59ml with deionized water to obtain an impregnation solution. 100g of support Z1 was weighed and impregnated with the impregnation solution in 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 D1.

[0111] Comparative Example 2

[0112] (1) Preparation of modified ZSM-5 molecular sieve: Similar to Example 1, except that no thiolated compound was added in this comparative example.

[0113] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0114] (3) Preparation of catalyst: Similar to Example 1, except that the catalyst support prepared in this comparative example is used, and the final catalyst D2 is obtained.

[0115] Comparative Example 3

[0116] (1) Preparation of modified ZSM-5 molecular sieve:

[0117] 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 S-1.

[0118] 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 100g of the above-mentioned dealuminated nano-HZSM-5 molecular sieve S-1 to the prepared potassium hydroxide solution and stir for 1 hour. Then add 95.7g of hexadecyltrimethylammonium chloride, 25.9g of zinc acetate dihydrate, and 10.1g of thioacetylammonium, and stir for 1 hour to obtain solution S-1. [The text abruptly ends here, likely due to an incomplete sentence or missing information.] -1 was placed in a crystallization vessel and crystallized for the first time at 100℃ for 24 hours in a drying oven, and then the temperature was raised to 170℃ for a second crystallization for 24 hours. The crystallized product was then filtered and washed with 0.5 mol / L ammonium chloride solution until the pH of the product eluent was 9. The resulting filter cake was dried at 120℃ for 120 minutes in a drying oven and calcined in a muffle furnace at 550℃ for 240 minutes to obtain zinc and potassium in-situ modified microporous-mesoporous ZSM-5 molecular sieve D3 (i.e. modified ZSM-5 molecular sieve).

[0119] (2) Preparation of catalyst support: Similar to Example 1, except that the modified ZSM-5 molecular sieve prepared in this comparative example is used.

[0120] (3) Preparation of catalyst: Similar to Example 1, except that the catalyst support prepared in this comparative example is used to finally obtain catalyst D3.

[0121] 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%.

[0122] Table 1 Physicochemical properties of the catalyst

[0123] catalyst A1 A2 A3 A4 A5 A6 D1 D2 D3 <![CDATA[Total specific surface area, m 2 / g]]> 328 279 305 315 321 308 278 309 318 <![CDATA[External specific surface area, m 2 / g]]> 106 112 98 103 105 95 65 108 102 <![CDATA[Total pore volume, cm 3 / g]]> 0.28 0.33 0.33 0.30 0.29 0.29 0.24 0.28 0.29 <![CDATA[Mesoporous pore volume, cm 3 / g]]> 0.21 0.24 0.23 0.22 0.21 0.20 0.12 0.17 0.20 Mesoporous ratio, % 69.1 69.7 69.7 73.3 72.4 69.0 50.0 60.7 69.0 L / B 5.0 4.1 6.2 6.8 6.5 5.2 2.7 4.0 4.4 <![CDATA[Al2O3,%]]> 15.3 34.2 13.1 14.8 14.6 15.1 14.7 14.9 15.4 <![CDATA[SiO2,%]]> 75.3 57.9 69.0 72.7 72.4 75.3 78.4 75.6 76.4 ZnO, % 4.03 3.00 8.85 6.59 6.53 5.04 3.48 4.15 3.64 <![CDATA[Ga2O3,%]]> 1.14 1.14 1.93 1.14 1.52 1.52 1.14 1.14 1.14 NiO, % 1.14 1.14 1.93 1.14 1.52 1.52 1.14 1.14 1.14 <![CDATA[La2O3,%]]> 1.14 1.14 1.93 1.14 1.52 1.52 1.14 1.14 1.14 <![CDATA[K2O,%]]> 1.14 0.88 2.33 1.72 1.13 0 0 1.12 1.14 <![CDATA[P2O5,%]]> 0.81 0.60 0.93 0.77 0.78 0 0 0.81 0

[0124] 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 the feedstock for catalytic heavy gasoline is introduced.

[0125] Hydrogenation reaction conditions: reaction temperature 340℃, 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.

[0126] Table 2 Evaluation results of olefin aromatization of the catalyst

[0127]

[0128] As can be seen from the data in Tables 1 and 2, the low-carbon hydrocarbon aromatization catalyst prepared by the method of the present invention exhibits significantly better low-temperature olefin reduction activity and C7-C9 aromatic hydrocarbon shape selectivity than the catalyst prepared in the comparative example during the olefin aromatization reaction. This comprehensively solves the problems of poor low-temperature aromatization activity and shape selectivity of conventional aromatization catalysts, as well as the easy carbon deposition and deactivation of the catalyst. Examples 1 and 2 primarily achieved physical control of the catalyst's acid content and mesoporous structure by adjusting the proportion of molecular sieve addition, increasing the mesoporous ratio of alumina. Potassium hydroxide was used as both an alkali source and a precursor for the modified metal additive, effectively controlling 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 1, 3, 4, and 5 primarily controlled the addition content of zinc, nickel, lanthanum, gallium, and phosphorus, as well as the amount of mesoporous template agent. Ammonium dihydrogen phosphate was used as both a complexing agent and a modifying additive. Zinc reacted with the framework aluminum to generate a moderately strong L-acid (ZnOH+) that facilitates the aromatization reaction, reducing the amount of strong acid while increasing the amount of moderately strong acid, effectively increasing the catalyst's L / B ratio, increasing the proportion of moderately strong L-acid, achieving comprehensive control of the molecular sieve's acid distribution, and solving the aromatization problem. Problems such as poor selectivity in molecular sieve structure were encountered. Example 6 aimed to regulate the crystallinity, specific surface area, and acid distribution of ZSM-5 molecular sieve by replacing the alkali source with sodium hydroxide, the template agent with hexadecyltrimethylammonium chloride, and the thiocarboxylic compound with thioacetamide, thereby 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 a significant decrease in catalyst specific surface area, mesopore ratio, and L / B, a significant decrease in catalyst olefin aromatization activity, and a significant increase in cracking activity. Compared with Example 1, Comparative Example 2 did not introduce thiocarboxylic compounds during the molecular sieve alkali modification and hydrothermal crystallization process, resulting in a decrease in the mesopore ratio and L / B of the prepared catalyst, which existed in the form of zinc oxide. This prevented in-situ modification of strong acids on the molecular sieve surface, leading to high levels of strong acid and high levels of acid on the outer surface. This resulted in the loss of modifying agents during catalyst use, and the catalyst exhibited high cracking activity in the early stages of the reaction, easily generating polycyclic aromatic hydrocarbons and other side reactions, leading to severe delays in the drying point. Compared with Example 1, Comparative Example 3 did not adjust the pH value before adding zinc acetate dihydrate, and did not add ammonium dihydrogen phosphate and ethylenediamine as complexing agents. As a result, the zinc compound did not form a stable complex, making it difficult to react completely with the aluminum skeleton to generate a medium-strong L acid (ZnOH+) and zinc metal sulfide. This resulted in poor low-temperature aromatization activity and shape selectivity of the catalyst, with fewer C7-C9 aromatics generated. The poor low-temperature shape-selective aromatization of the catalyst was not conducive to product distribution.

[0129] Meanwhile, under the above hydrogenation reaction conditions, taking Example 5 and Comparative Examples 1 and 3 as examples, after 20 days of operation, the carbon content on the catalyst was 8.2%, 13.1%, and 11.6%, respectively, indicating that the present invention has effectively solved the problem of easy carbon deposition on the catalyst.

[0130] 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 microporous-mesoporous 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; The dealuded nano-HZSM-5 molecular sieve was added to an inorganic alkaline solution. After adding a mesoporous template agent and controlling the pH of the system to 13-14, a zinc-containing compound, a complexing agent, and a thiolated compound were added. After hydrothermal crystallization, filtration, drying, and calcination, a microporous-mesoporous modified ZSM-5 molecular sieve was obtained.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the complexing agent to the zinc-containing compound is 0.6 to 2.5; The molar ratio of the zinc-containing compound to the thio 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. The mass ratio of the dealuded nano HZSM-5 molecular sieve, the zinc-containing compound, and the mesoporous template agent is 1:(0.18-0.40):(0.7-1.1).

4. The preparation method according to claim 1, characterized in that, After adding the mesoporous template agent, the pH of the system is controlled with an alkaline reagent, wherein the alkaline reagent is selected from urea and / or ammonia.

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 and / or thiosulfate; The complexing agent is selected from at least one of ammonium dihydrogen phosphate, ethylenediamine and EDTA; 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 and / or ammonium nitrate; 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 microporous-mesoporous modified ZSM-5 molecular sieve prepared by the method of any one of claims 1-11.

13. The application of the microporous-mesoporous 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 microporous-mesoporous 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 microporous-mesoporous modified ZSM-5 molecular sieve is prepared by the method of preparing modified ZSM-5 molecular sieve according to 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 is impregnated with a loaded metal promoter, 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, It includes a carrier and an active component, wherein the carrier comprises nano-ZSM-5 molecular sieve and alumina; and the active component comprises zinc, Group IIIA metals, Group VIII metals and Group IIIB metals.

17. The low-carbon hydrocarbon aromatization catalyst according to claim 16, characterized in that, The low-carbon hydrocarbon aromatization catalyst also includes potassium oxide and / or phosphorus oxide.

18. The low-carbon hydrocarbon aromatization catalyst according to claim 16 or 17, characterized in that, The low-carbon hydrocarbon aromatization catalyst has a microporous-mesoporous structure, and the total acid content of the low-carbon hydrocarbon aromatization catalyst is 0.10-0.30 mmol / g, the strong Brønsted acid content is 0.01-0.08 mmol / g, the proportion of medium-strong acids is ≥30%, and the L / B ratio is 2-8.

19. An aromatization reaction of a distillate oil, characterized in that, The low-carbon hydrocarbon aromatization catalyst prepared by the method of claim 16, or the low-carbon hydrocarbon aromatization catalyst of claim 17 or claim 18.

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