Preparation method and application of high-stability catalyst for preparing aromatic hydrocarbon-based aviation kerosene from methanol

Abstract

The present application relates to the technical field of catalysts, and discloses a preparation method and application of a high-stability catalyst for preparing aromatic hydrocarbons from methanol, which comprises the following steps: S1: adding a silicon source, an aluminum source, tetrapropylammonium hydroxide and urea into water, and performing a hydrothermal crystallization reaction; the reaction product is subjected to aerobic calcination to obtain a layered ZSM-5 molecular sieve; S2: mixing the layered ZSM-5 molecular sieve and an alkali solution, and then heating and stirring; after filtration and drying, ammonia exchange is performed to obtain a layered mesoporous ZSM-5 molecular sieve; and S3: mixing 50-80% of the layered mesoporous ZSM-5 molecular sieve and 20-50% of a graphite additive according to the mass percentage, and then ball milling. The layered mesoporous ZSM-5 molecular sieve and the graphite additive are compounded and ball milled, a catalyst with an alternating stacking structure of molecular sieve-graphite additive is formed, the structure-property of the molecular sieve and the graphite additive is synergized, and the catalytic activity and stability of the catalyst are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a preparation method and application of a high-stability catalyst for methanol-to-arenaviation fuel. BACKGROUND

[0002] Developing sustainable aviation fuel (SAF) as a substitute for fossil aviation fuel has become one of the core paths for the aviation industry to reduce emissions. Among them, methanol can be produced by CO2 hydrogenation or biomass conversion driven by renewable energy, and has the potential for carbon neutralization in the whole life cycle. Therefore, the technical route of preparing sustainable aviation fuel from methanol has attracted widespread attention. The core process of methanol-to-sustainable aviation fuel is to convert methanol into a hydrocarbon mixture rich in aromatics (mainly C8~C 12 aromatics) through a catalyst, and then obtain a fuel meeting the aviation fuel standard through steps such as hydro-upgrading. However, the industrialization of this technology faces many challenges, and the stability of the catalyst restricts its large-scale application.

[0003] At present, the commonly used catalysts are mainly molecular sieves (such as ZSM-5). For example, a patent with publication number CN120483183A discloses a preparation method of a mesoporous Zn-ZSM-5 molecular sieve for methanol-to-aromatics. The zinc gluconate is mixed uniformly with an aluminum source, a silicon source, and a template agent, and then placed in a sealed reaction container for hydrothermal crystallization. Then, the sodium-type molecular sieve is obtained by sequentially washing, drying, and calcining. The sodium-type molecular sieve is subjected to multiple ion exchange with an ammonium chloride solution, and then sequentially subjected to suction filtration, washing, drying, and calcining to obtain the mesoporous Zn-ZSM-5 molecular sieve. However, the traditional ZSM-5 molecular sieve (blocky or spherical morphology) has the following defects: (1) the micropore channel is long (diffusion distance 1~5 μm), and the C8~C 12 aromatic product has a long residence time, which is easy to generate polycyclic aromatic carbon; (2) the specific surface area is low, the active sites are not exposed enough, and the byproduct water easily erodes the framework aluminum, leading to dealuminization and deactivation, resulting in a generally short single-pass life (usually less than 100 hours) of the existing catalyst. Frequent regeneration not only increases energy consumption and operating costs, but also shortens the overall service life of the catalyst, which seriously hinders the economic efficiency and industrialization process of the methanol-to-aromatics-based sustainable aviation fuel technology.

[0004] Therefore, it is an urgent need to develop a high-stability, long-life catalyst system with structure-property synergy to promote the breakthrough of the methanol-to-aromatics-based sustainable aviation fuel technology. SUMMARY

[0005] In order to solve the above technical problems, the application provides a preparation method and application of a high-stability catalyst for preparing aromatic hydrocarbon-based aviation kerosene from methanol, which forms a catalyst with an alternating stacking structure of molecular sieve-graphite additive by compounding and ball milling of a sheet mesoporous ZSM-5 molecular sieve and graphite additive, so that the structure-property dual synergy of the molecular sieve and the graphite additive is achieved, thereby improving the catalytic activity and stability of the catalyst.

[0006] The object of the application is achieved by the following technical solutions.

[0007] In a first aspect, the application provides a preparation method of a high-stability catalyst for preparing aromatic hydrocarbon-based aviation kerosene from methanol, which comprises the following steps:

[0008] S1: adding a silicon source, an aluminum source, tetrapropylammonium hydroxide and urea into water to perform a hydrothermal crystallization reaction, and performing oxygen calcination on a reaction product to obtain a sheet ZSM-5 molecular sieve;

[0009] S2: mixing the sheet ZSM-5 molecular sieve and an alkali solution, heating and stirring, filtering and drying, and performing ammonia exchange to obtain a sheet mesoporous ZSM-5 molecular sieve; the sheet mesoporous ZSM-5 molecular sieve has a silicon-aluminum molar ratio of 20-80, an a-axis length of 1-3 μm, a b-axis length of 50-400 nm and a c-axis length of 300-800 nm;

[0010] S3: mixing 50-80 % of the sheet mesoporous ZSM-5 molecular sieve and 20-50 % of graphite additive according to the mass percentage, and ball milling to obtain a catalyst, wherein the catalyst has an alternating stacking structure of molecular sieve-graphite additive.

[0011] The catalyst in the application is composed of the sheet mesoporous ZSM-5 molecular sieve and the graphite additive, both of which have a layered structure, and the size of the sheet mesoporous ZSM-5 molecular sieve is controlled, so that the combination potential of the large surface area (010 crystal surface of the molecular sieve and the layered surface of the graphite) is the lowest, and the surface is smooth. In the ball milling process, the surface face-to-face contact of the large surface area is inclined to form a stable open framework of the alternating stacking of the molecular sieve-graphite additive. Other additives (for example, SiO2) have a spherical structure, and it is difficult to form face-to-face contact with the sheet mesoporous ZSM-5 molecular sieve, so that the dense accumulation easily blocks the molecular sieve channel structure, and the structure-property synergy cannot be achieved.

[0012] The catalyst with the alternating stacking structure of the molecular sieve-graphite additive has the following advantages:

[0013] On the one hand, the sheet structure of the graphite additive partially covers or isolates the strong acid sites on the surface of the ZSM-5 molecular sieve and between the particles, thereby effectively weakening the locally excessive acid environment. At the same time, the π-electron system of the graphite can weakly interact with the Brønsted acid sites of the molecular sieve, further reducing the acid strength and inhibiting the excessive condensation reaction of olefins and aromatic hydrocarbons. As a result, the generation rate of polycyclic aromatic hydrocarbons and coke during aromatization is significantly reduced, the coke morphology is more easily regenerated and removed, and the deactivation rate of the catalyst is greatly slowed down. Moreover, by controlling the molar ratio of silicon and aluminum of the ZSM-5 molecular sieve, the carbon deposition can be further reduced. When the molar ratio of silicon and aluminum is too low, the carbon deposition speed is accelerated, and when the molar ratio of silicon and aluminum is increased, the acid sites are reduced, and the carbon deposition speed is slowed down, but when the molar ratio of silicon and aluminum is increased to a certain extent, the decrease in acidity will lead to a decrease in methanol conversion rate.

[0014] On the other hand, since the acid sites of the ZSM-5 molecular sieve are required in the present application, the defined molecular sieve has a low molar ratio of silicon and aluminum (20-80), and the hydrophobicity is much weaker than that of graphite. The low molar ratio of silicon and aluminum of the molecular sieve itself is not hydrothermally stable, and the byproduct water needs to be discharged in time to avoid collapse of the framework. The strong hydrophobicity (contact angle > 120°) of the graphite additive can form a local drainage channel between the ZSM-5 molecular sieve particles, reducing the residence and adsorption of water molecules in the pores, thereby effectively avoiding the poisoning of the acid sites by the byproduct water and the dealumination damage to the molecular sieve framework.

[0015] Therefore, the graphite additive can form a structure-property dual synergistic effect with the sheet mesoporous ZSM-5 molecular sieve, and directly coat and grow an S-1 shell layer on the surface of the sheet mesoporous ZSM-5 molecular sieve. Although this can also enhance the hydrophobicity of the molecular sieve surface, due to the diffusion limitation of the S-1 pores, it is difficult to detach the large molecular product, which accumulates in the molecular sieve pores, leading to catalyst carbon deposition and deactivation. Moreover, by controlling the compounding ratio of the sheet mesoporous ZSM-5 molecular sieve and the graphite additive, the catalytic stability is further improved. When the proportion of the sheet mesoporous ZSM-5 molecular sieve is too large, the hydrophobicity of the graphite additive is insufficient, resulting in insignificant improvement in the catalyst life; and when the proportion of the graphite additive is too large, the acid sites of the molecular sieve are insufficient, which will cause a decrease in the methanol conversion rate.

[0016] Preferably, in step S1, the silicon source is tetraethyl orthosilicate (TEOS), and the aluminum source is aluminum isopropoxide, aluminum sulfate or pseudo-boehmite.

[0017] Preferably, in step S1, the molar ratio of silicon elements in the silicon source to tetrapropylammonium hydroxide and urea is 1:0.1-0.5:0.1-2.5.

[0018] Preferably, in step S1, the molar ratio of silicon elements in the silicon source to water is 1:20-33.5.

[0019] Preferably, in step S1, the hydrothermal crystallization reaction is performed at a temperature of 120-200 DEG C for 24-80 hours.

[0020] Preferably, in step S1, the oxygen-containing calcination is performed at a temperature of 500-600 DEG C for 3-5 hours.

[0021] Preferably, in step S2, the alkali solution has a concentration of 0.1-0.3 M; the alkali solution is a NaOH solution; the heating and stirring is performed at a temperature of 70-90 DEG C for 1-2 hours.

[0022] The molecular sieve is selectively dissolved in the alkali solution to form a mesoporous structure by selectively dissolving silicon atoms in the molecular sieve framework; when the alkali concentration is too low, the mesoporous content is insufficient, and the molecular sieve is prone to rapid carbon deposition; when the alkali concentration is too high, the molecular sieve framework collapses, and the catalytic performance is greatly reduced.

[0023] Preferably, in step S2, the ammonium exchange is ion exchange of the sheet ZSM-5 molecular sieve with an ammonium salt solution; the ammonium salt solution is an ammonium chloride solution; the ion exchange is heating to 80-90 DEG C, stirring for 1-2 hours, and repeating the ion exchange three or more times until Na+ is replaced by NH4+. + The H-type molecular sieve is generated.

[0024] Preferably, in step S3, the graphite additive is graphite and / or graphene; the graphite additive has a length and width of 2-10 microns.

[0025] Preferably, in step S3, the ball milling is performed at a speed of 300-600 rpm for 1-3 hours.

[0026] In a second aspect, the application also provides a catalyst prepared by the above preparation method for use in the preparation of an aromatic hydrocarbon-based aviation fuel from methanol.

[0027] Preferably, the aromatic hydrocarbon-based aviation fuel includes aromatic hydrocarbons with 8-12 carbon atoms.

[0028] Preferably, the reaction conditions for the preparation of the aromatic hydrocarbon-based aviation fuel from methanol include: the reaction is performed in a fixed bed or a fluidized bed under a mixed atmosphere of hydrogen and an inert gas at a temperature of 350-450 DEG C and a pressure of normal pressure, and the methanol space velocity is 0.2-2 h-1. -l .

[0029] Preferably, the inert gas is one or more of nitrogen, helium, and argon; and the molar ratio of the hydrogen to the inert gas is 0.1-0.5:1.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] (1) The catalyst with the molecular sieve-graphite additive alternating stacking structure is formed by adopting the sheet layer mesoporous ZSM-5 molecular sieve and graphite additive compounding ball milling, so that the structure-property double synergy of the molecular sieve and the graphite additive is realized, and therefore the catalytic activity and stability of the catalyst are improved;

[0032] (2) The reaction performance of the molecular sieve acid site, the diffusion performance of the mesopore and the hydrophobic performance of the graphite are balanced by limiting the compounding ratio of the sheet layer mesoporous ZSM-5 molecular sieve and the graphite additive and the silicon-aluminum ratio of the molecular sieve, and therefore the stability of the catalyst is further improved;

[0033] (3) Under the same methanol to aromatic hydrocarbon-based aviation kerosene reaction conditions, the catalyst in the application can have higher catalytic stability and longer catalytic reaction life, and the regeneration consumption of the catalyst is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is the SEM graph of the sheet layer mesoporous ZSM-5 molecular sieve in Example 1.

[0035] Figure 2 It is the SEM graph of the catalyst in Example 1.

[0036] Figure 3 It is the time-conversion rate graph of the catalyst in the methanol to aromatic hydrocarbon-based aviation kerosene reaction in Example 1.

[0037] Figure 4 It is the nitrogen adsorption-desorption curve graph of the sheet layer mesoporous ZSM-5 molecular sieve in Example 2.

[0038] Figure 5 It is the gas chromatogram of the product in Example 3. DETAILED DESCRIPTION

[0039] The technical solutions of the application are described below with specific examples, but the protection scope of the application is not limited thereto.

[0040] Example 1

[0041] The catalyst composition is as follows in terms of mass percentage: sheet layer mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 40) 70 %, graphite 30 %.

[0042] The preparation method of the catalyst comprises the following steps:

[0043] S1: A silicon source (tetraethyl orthosilicate), an aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added into water to form a mixed solution according to a molar ratio of SiO2:Al: tetrapropylammonium hydroxide: urea: water of 1:0.25:0.1:2.5:20, and a hydrothermal crystallization reaction was performed in a sealed container, and the hydrothermal crystallization was performed at a temperature of 180°C for 48 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h to obtain a sheet layer ZSM-5 molecular sieve, and the sheet layer thickness was 80±10 nm;

[0044] S2: The sheet layer ZSM-5 molecular sieve and a 0.1 M NaOH solution were mixed according to a ratio of 1 g:50 mL, and then heated and stirred at 70°C, and the stirring time was 1 h; after the stirring was completed, filtration and drying were performed; ammonia exchange was performed, the sheet layer ZSM-5 molecular sieve and a 1 M NH4Cl solution were mixed according to a ratio of 1 g:50 mL, and then heated to 80°C, and stirred for 2 h, and the process was repeated three times; after the process was completed, filtration and drying were performed to obtain a sheet layer mesoporous ZSM-5 molecular sieve;

[0045] S3: 70% of the sheet layer mesoporous ZSM-5 molecular sieve and 30% of graphite were uniformly mixed and ground, and then ball milled at a rotation speed of 400 rpm for 2 h to obtain a catalyst.

[0046] The above catalyst was used in a methanol-to-arene sustainable aviation fuel reaction in a fixed bed, a hydrogen / nitrogen mixed gas (a hydrogen / nitrogen molar ratio of 0.1:1) was used as a reaction atmosphere, the reaction temperature was 450°C, the methanol space velocity was 0.5 h -1 .

[0047] Example 2

[0048] The catalyst composition included, by mass percentage, 80% of a sheet layer mesoporous ZSM-5 molecular sieve (a silicon / aluminum molar ratio of 20) and 20% of graphite.

[0049] The catalyst preparation method included the following steps:

[0050] S1: A silicon source (tetraethyl orthosilicate), an aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added into water to form a mixed solution according to a molar ratio of SiO2:Al: tetrapropylammonium hydroxide: urea: water of 1:0.25:0.1:2.5:20, and a hydrothermal crystallization reaction was performed in a sealed container, and the hydrothermal crystallization was performed at a temperature of 180°C for 48 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h to obtain a sheet layer ZSM-5 molecular sieve, and the sheet layer thickness was 80±10 nm;

[0051] S2: The sheet layer ZSM-5 molecular sieve and 0.2 M NaOH solution were mixed in a ratio of 1 g: 50 mL, and then heated and stirred at 80°C for 1.5 h; after stirring, filtration and drying were performed; ammonia exchange was carried out, the sheet layer ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed in a ratio of 1 g: 50 mL, heated to 80°C, and stirred for 2 h, repeated three times; after completion, filtration and drying were performed to obtain the sheet layer mesoporous ZSM-5 molecular sieve;

[0052] S3: 80% of the sheet layer mesoporous ZSM-5 molecular sieve and 20% of graphite were mixed and ground uniformly according to the mass percentage, and then ball milling was performed at a speed of 400 rpm for 2 h to obtain the catalyst.

[0053] The above catalyst was used in the methanol to aromatic sustainable aviation fuel reaction in a fixed bed, the reaction atmosphere was hydrogen / nitrogen mixed gas (hydrogen / nitrogen molar ratio was 0.2:1), the reaction temperature was 450°C, the methanol space velocity was 0.5 h -1 .

[0054] Example 3

[0055] The catalyst composition was as follows according to the mass percentage: sheet layer mesoporous ZSM-5 molecular sieve (silicon aluminum molar ratio 80) 50%, graphite 50%.

[0056] The preparation method of the catalyst comprises the following steps:

[0057] S1: The silicon source (tetraethyl orthosilicate), aluminum source (isopropyl alcohol aluminum), tetrapropyl ammonium hydroxide and urea were added into water to form a mixed solution according to the molar ratio of SiO2:Al: tetrapropyl ammonium hydroxide: urea: water 1:0.0125:0.5:0.1:33.5, and a hydrothermal crystallization reaction was carried out in a sealed container at a temperature of 200°C for 24 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h to obtain the sheet layer ZSM-5 molecular sieve, and the sheet layer thickness was 300±10 nm;

[0058] S2: The sheet layer ZSM-5 molecular sieve and 0.3 M NaOH solution were mixed in a ratio of 1 g: 50 mL, and then heated and stirred at 90°C for 2 h; after stirring, filtration and drying were performed; ammonia exchange was carried out, the sheet layer ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed in a ratio of 1 g: 50 mL, heated to 80°C, and stirred for 2 h, repeated three times; after completion, filtration and drying were performed to obtain the sheet layer mesoporous ZSM-5 molecular sieve;

[0059] S3: By mass percentage, 50% of the lamellar mesoporous ZSM-5 molecular sieve and 50% of graphite are mixed and ground evenly, and then ball-milled at a speed of 400 rpm for 2 hours to obtain the catalyst.

[0060] The above catalyst was used in a fixed-bed reactor to produce aromatic-based sustainable jet fuel from methanol. The reaction atmosphere was a hydrogen / helium mixture (hydrogen / helium molar ratio of 0.1:1), the reaction temperature was 450℃, and the methanol space velocity was 0.5 h⁻¹. -1 .

[0061] Example 4

[0062] The catalyst composition, by mass percentage, is: 60% lamellar mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 20) and 40% graphite.

[0063] The preparation method of the catalyst includes the following steps:

[0064] S1: According to the molar ratio of SiO2:Al:tetrapropylammonium hydroxide:urea:water of 1:0.02:0.4:2.5:30, silicon source (tetraethyl silicate), aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added to water to form a mixed solution. The solution was subjected to hydrothermal crystallization reaction in a closed container at 200℃ for 48 h. After the reaction was completed, the reaction product was calcined in air at 550℃ for 4 h to obtain sheet-like ZSM-5 molecular sieve with a sheet thickness of 100±10 nm.

[0065] S2: Mix the sheet-like ZSM-5 molecular sieve and 0.1 M NaOH solution at a ratio of 1 g: 50 mL, heat and stir at 70 °C for 1 h; after stirring, filter and dry; perform ammonia exchange by mixing the sheet-like ZSM-5 molecular sieve and 1 M NH4Cl solution at a ratio of 1 g: 50 mL, heating to 80 °C, stirring for 2 h, and repeating three times; after completion, filter and dry to obtain the sheet-like mesoporous ZSM-5 molecular sieve.

[0066] S3: By mass percentage, 60% of the lamellar mesoporous ZSM-5 molecular sieve and 40% of graphite are mixed and ground evenly, and then ball-milled at 400 rpm for 2 hours to obtain the catalyst.

[0067] The above catalyst was used in a fixed-bed reaction to produce aromatic-based sustainable jet fuel from methanol. The reaction atmosphere was a hydrogen / argon mixture (hydrogen / argon molar ratio of 0.5:1), the reaction temperature was 400℃, and the methanol space velocity was 0.8 h⁻¹. -1 .

[0068] Example 5

[0069] Catalyst composition by mass percentage: 70% of layered mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 20), 30% of graphite.

[0070] The preparation method of the catalyst comprises the following steps:

[0071] S1: A mixed solution is formed by adding a silicon source (tetraethyl orthosilicate), an aluminum source (isopropyl alcohol aluminum), tetrapropyl ammonium hydroxide, and urea into water according to a molar ratio of SiO2:Al: tetrapropyl ammonium hydroxide: urea: water of 1:0.05:0.5:1:33.5, a hydrothermal crystallization reaction is performed in a sealed container, and the hydrothermal crystallization is performed at a temperature of 180℃ for 48 h; after the reaction is completed, the obtained reaction product is calcined at 550℃ in air for 4 h to obtain a layered ZSM-5 molecular sieve, and the thickness of the layered ZSM-5 molecular sieve is 200±10 nm;

[0072] S2: The layered ZSM-5 molecular sieve and a 0.1 M NaOH solution are mixed according to a ratio of 1 g:50 mL, and then heated and stirred at 70℃, and the stirring time is 2 h; after the stirring is completed, filtration and drying are performed; ammonia exchange is performed, the layered ZSM-5 molecular sieve and a 1 M NH4Cl solution are mixed according to a ratio of 1 g:50 mL, and then heated to 80℃, and stirred for 2 h, and the process is repeated three times; after the process is completed, filtration and drying are performed to obtain a layered mesoporous ZSM-5 molecular sieve;

[0073] S3: 70% of the layered mesoporous ZSM-5 molecular sieve and 30% of graphite are uniformly mixed and ground, ball milling is performed at a rotation speed of 400 rpm for 2 h to obtain a catalyst.

[0074] The above catalyst is used in a fixed bed to perform a methanol-to-arene sustainable aviation fuel reaction, a hydrogen / nitrogen mixed gas (a hydrogen / nitrogen molar ratio is 0.5:1) is used as a reaction atmosphere, the reaction temperature is 350℃, the methanol space velocity is 0.2 h-1, and the methanol conversion rate is 100%, and the selectivity of the sustainable aviation fuel is 100%. -1 .

[0075] Example 6

[0076] Catalyst composition by mass percentage: 70% of layered mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 40), 30% of graphite.

[0077] The preparation method of the catalyst comprises the following steps:

[0078] S1: Silicon source (tetraethyl orthosilicate), aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added into water to form a mixed solution according to the molar ratio of SiO2:Al: tetrapropylammonium hydroxide: urea: water being 1:0.25:0.1:2.5:20, and a hydrothermal crystallization reaction was carried out in a sealed container, and hydrothermal crystallization was carried out at a temperature of 180°C for 48 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h, and a sheet layer ZSM-5 molecular sieve was obtained, and the sheet layer thickness was 80±10 nm;

[0079] S2: The sheet layer ZSM-5 molecular sieve and 0.1 M NaOH solution were mixed according to a ratio of 1 g:50 mL, and then heated and stirred at 70°C, and the stirring time was 1 h; after stirring was completed, filtration and drying were carried out; ammonia exchange was carried out, the sheet layer ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed according to a ratio of 1 g:50 mL, and then heated to 80°C, and stirred for 2 h, and the operation was repeated three times; after completion, filtration and drying were carried out, and a sheet layer mesoporous ZSM-5 molecular sieve was obtained;

[0080] S3: 70% of the sheet layer mesoporous ZSM-5 molecular sieve and 30% of graphite were uniformly mixed and ground, and then ball milling was carried out at a rotation speed of 400 rpm for 2 h, and a catalyst was obtained.

[0081] The above catalyst was used in a methanol to aromatic sustainable aviation fuel reaction in a fixed bed, the reaction atmosphere was hydrogen / nitrogen mixed gas (the molar ratio of hydrogen / nitrogen was 0.3:1), the reaction temperature was 450°C, the methanol space velocity was 2 h -1 .

[0082] Comparative Example 1

[0083] The difference from Example 1 is that the catalyst only contains sheet layer mesoporous ZSM-5 molecular sieve (the molar ratio of silicon to aluminum is 40).

[0084] The preparation method of the catalyst comprises the following steps:

[0085] S1: Silicon source (tetraethyl orthosilicate), aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added into water to form a mixed solution according to the molar ratio of SiO2:Al: tetrapropylammonium hydroxide: urea: water being 1:0.25:0.1:2.5:20, and a hydrothermal crystallization reaction was carried out in a sealed container, and hydrothermal crystallization was carried out at a temperature of 180°C for 48 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h, and a sheet layer ZSM-5 molecular sieve was obtained, and the sheet layer thickness was 80±10 nm;

[0086] S2: The sheet layer ZSM-5 molecular sieve and 0.1 M NaOH solution were mixed in a ratio of 1 g: 50 mL, then heated and stirred at 70°C, and the stirring time was 1 h; after stirring was completed, filtration and drying were performed; ammonia exchange was performed, the sheet layer ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed in a ratio of 1 g: 50 mL, then heated to 80°C, and stirred for 2 h, and the process was repeated three times; after completion, filtration and drying were performed, and the catalyst was obtained.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that the catalyst is obtained after the S-1 shell layer is coated on the surface of the sheet layer mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 40).

[0089] The preparation method of the catalyst comprises the following steps:

[0090] S1: The silicon source (tetraethyl orthosilicate), aluminum source (isopropyl alcohol aluminum), tetrapropyl ammonium hydroxide and urea were added into water to form a mixed solution in a molar ratio of SiO2: Al: tetrapropyl ammonium hydroxide: urea: water 1: 0.25: 0.1: 2.5: 20, a hydrothermal crystallization reaction was performed in a sealed container, and the hydrothermal crystallization was performed at a temperature of 180°C for 48 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h, and the sheet layer ZSM-5 molecular sieve was obtained, and the sheet layer thickness was 80±10 nm;

[0091] S2: The sheet layer ZSM-5 molecular sieve and 0.1 M NaOH solution were mixed in a ratio of 1 g: 50 mL, then heated and stirred at 70°C, and the stirring time was 1 h; after stirring was completed, filtration and drying were performed; ammonia exchange was performed, the sheet layer ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed in a ratio of 1 g: 50 mL, then heated to 80°C, and stirred for 2 h, and the process was repeated three times; after completion, filtration and drying were performed, and the catalyst was obtained.

[0092] S3: The sheet layer mesoporous ZSM-5 molecular sieve was used as a seed, and an S-1 shell layer was coated on the surface thereof by a hydrothermal synthesis method: the silicon source (tetraethyl orthosilicate), tetrapropyl ammonium hydroxide and water were formed into a mixed solution in a molar ratio of silicon element in the silicon source: tetrapropyl ammonium hydroxide: water: silicon element in the molecular sieve 1: 0.1: 180: 1, stirring was performed at room temperature for 8 h, the sheet layer mesoporous ZSM-5 molecular sieve was added and stirring was continued for 1 h, a hydrothermal crystallization reaction was performed in a sealed container, and the hydrothermal crystallization was performed at a temperature of 170°C for 72 h; after the reaction was completed, the obtained reaction product was calcined in air at 550°C for 4 h, and the catalyst was obtained.

[0093] Comparative Example 3

[0094] The difference from Example 1 is that the additive used in the catalyst is SiO2 powder.

[0095] The catalyst composition by mass percentage: 70% of the sheet mesoporous ZSM-5 molecular sieve (molar ratio of silicon to aluminum 40), 30% of SiO2 powder (particle size 200-300 nm).

[0096] The preparation method of the catalyst comprises the following steps:

[0097] S1: according to the molar ratio of SiO2: Al: tetrapropylammonium hydroxide: urea: water 1: 0.25: 0.1: 2.5: 20, the silicon source (tetraethyl orthosilicate), aluminum source (isopropyl alcohol aluminum), tetrapropylammonium hydroxide and urea are added into water to form a mixed solution, and a hydrothermal crystallization reaction is carried out in a sealed container, and the hydrothermal crystallization is carried out at a temperature of 180℃ for 48h; after the reaction is completed, the obtained reaction product is calcined at 550℃ in air for 4h, to obtain a sheet ZSM-5 molecular sieve, and the sheet thickness is 80±10 nm;

[0098] S2: the sheet ZSM-5 molecular sieve and 0.1 M NaOH solution are mixed according to the ratio of 1g: 50mL, and then heated and stirred at 70℃, and the stirring time is 1h; after the stirring is completed, filtration and drying are carried out; ammonia exchange is carried out, the sheet ZSM-5 molecular sieve and 1 M NH4Cl solution are mixed according to the ratio of 1g: 50mL, and then heated to 80℃, and stirred for 2h, and the process is repeated three times; after completion, filtration and drying are carried out, to obtain a sheet mesoporous ZSM-5 molecular sieve;

[0099] S3: according to the mass percentage, 70% of the sheet mesoporous ZSM-5 molecular sieve is uniformly mixed and ground with 30% of SiO2 powder, and then ball milling is carried out, the ball milling speed is 400rpm, and the time is 2h, to obtain a catalyst.

[0100] Comparative Example 4

[0101] The difference from Example 2 is that the mass ratio of the sheet mesoporous ZSM-5 molecular sieve in the catalyst is too large. Specifically, the catalyst composition by mass percentage: 90% of the sheet mesoporous ZSM-5 molecular sieve (molar ratio of silicon to aluminum 20), 10% of graphite.

[0102] Comparative Example 5

[0103] The difference from Example 3 is that the mass ratio of the sheet mesoporous ZSM-5 molecular sieve in the catalyst is too small. Specifically, the catalyst composition by mass percentage: 30% of the sheet mesoporous ZSM-5 molecular sieve (molar ratio of silicon to aluminum 80), 70% of graphite.

[0104] Comparative Example 6

[0105] The difference from Example 2 is that the silicon to aluminum ratio of the sheet mesoporous ZSM-5 molecular sieve in the catalyst is too large.

[0106] The catalyst composition, by mass percentage, is: 80% lamellar mesoporous ZSM-5 molecular sieve (silicon-aluminum molar ratio 150) and 20% graphite.

[0107] The preparation method of the catalyst includes the following steps:

[0108] S1: According to the molar ratio of SiO2:Al:tetrapropylammonium hydroxide:urea:water of 1:0.0067:0.2:1:25, silicon source (tetraethyl silicate), aluminum source (aluminum isopropoxide), tetrapropylammonium hydroxide and urea were added to water to form a mixed solution. The solution was subjected to hydrothermal crystallization reaction in a closed container at 120℃ for 80 h. After the reaction was completed, the reaction product was calcined in air at 550℃ for 4 h to obtain sheet ZSM-5 molecular sieve with a sheet thickness of 150±10 nm.

[0109] S2: The sheet-like ZSM-5 molecular sieve and 0.2 M NaOH solution were mixed at a ratio of 1 g: 50 mL and heated and stirred at 80 °C for 1.5 h. After stirring, the mixture was filtered and dried. For ammonia exchange, the sheet-like ZSM-5 molecular sieve and 1 M NH4Cl solution were mixed at a ratio of 1 g: 50 mL and heated to 80 °C for 2 h. This process was repeated three times. After the process was completed, the mixture was filtered and dried to obtain the sheet-like mesoporous ZSM-5 molecular sieve.

[0110] S3: By mass percentage, 80% of the lamellar mesoporous ZSM-5 molecular sieve and 20% of graphite are mixed and ground evenly, and then ball-milled at 400 rpm for 2 hours to obtain the catalyst.

[0111] Table 1. Catalytic performance of the catalysts in Examples 1-6 and Comparative Examples 1-6 in the methanol-to-aromatics-based jet fuel reaction.

[0112]

[0113] Note: The stable operating time of the catalyst refers to the time during which the fixed bed reaction continues until the catalyst shows obvious deactivation (the methanol conversion rate begins to decline).

[0114] like Figure 1 The image shown is an SEM image of the mesoporous ZSM-5 molecular sieve in Example 1. It can be seen that the a-axis length of the mesoporous ZSM-5 molecular sieve is 2±0.5 μm, the b-axis (sheet thickness) length is 100±10 nm, and the c-axis length is 500±10 nm. Figure 2 As shown, after ball milling the lamellar mesoporous ZSM-5 molecular sieve and graphite in Example 1, a structure of alternating stacked molecular sieve and graphite additives can be clearly seen. Figure 3As shown, the catalyst in Example 1 did not show obvious deactivation until after 350 h of continuous stable operation, indicating that the catalyst has a long service life. As shown in Table 1, the catalyst in Example 1 has a higher selectivity for aromatics than the catalyst in Comparative Example 1. Figure 4 As shown in Figure 2, the nitrogen adsorption-desorption curve of the mesoporous ZSM-5 molecular sieve prepared in Example 2 has a typical type IV isotherm with a clear hysteresis loop, indicating that the molecular sieve has a mesoporous structure. As shown in Figure 3, the gas chromatogram of the product obtained in Example 2 shows that the product is mainly aromatics-based sustainable aviation kerosene (C8~C Figure 5 As shown in Figure 4, the gas chromatogram of the product obtained in Example 3 shows that the product is mainly aromatics-based sustainable aviation kerosene (C8~C 12 ).

[0115] As shown in Table 1, it can be seen from Comparative Example 1 and Example 1 that, compared with the pure molecular sieve catalyst, the hydrophobic graphite additive can significantly improve the stability of the methanol-to-aromatics-based sustainable aviation kerosene catalyst, and does not affect the selectivity of the aromatics-based aviation kerosene. The reason is that the diffusion of the water byproduct and the aromatics target product generated during the reaction is affected by the graphite. Due to the hydrophobic nature of the graphite, the byproduct water can accelerate the separation from the surface of the catalyst, pull the reaction equilibrium, and improve the catalytic performance of the catalyst; at the same time, the ordered coating of the graphite on the outer surface provides an ordered macropore, which promotes the separation of the target product aromatics from the channel, avoids the formation of carbon deposition, and thus increases the stability of the catalyst.

[0116] As shown in Table 1, it can be seen from Comparative Example 2 and Example 1 that, compared with the catalyst composition method of compounding the molecular sieve catalyst with the hydrophobic graphite additive, directly coating the S-1 shell on the outer surface of the molecular sieve to form a classic core-shell structure cannot improve the stability of the catalyst. The reason is that the methanol molecules react to generate the aromatics target product in the mesoporous sheet ZSM-5 molecular sieve, and the diffusion is limited by the S-1 channel of the shell layer; and compared with the mesoporous channel of the core layer, the ordered microporous structure of the shell layer seriously improves the diffusion resistance, which leads to the rapid plugging of the channel opening of the core layer mesoporous sheet ZSM-5 molecular sieve, and the service life of the catalyst is even lower than that of the pure mesoporous sheet ZSM-5 molecular sieve in Comparative Example 1. Therefore, it can be concluded that the hydrophobic additive for modifying the outer surface of the active molecular sieve can promote the desorption of the byproduct water and the aromatics target product from the surface of the catalyst on the one hand by virtue of the lipophilic hydrophobic property at the chemical level; and on the other hand, the ordered macroporous structure constructed by the additive can accelerate the diffusion and mass transfer of the above-mentioned substances in the reaction system. The two aspects synergistically promote the improvement of the stability of the catalyst.

[0117] As can be seen from Comparative Example 3 and Examples 1 and 2, when the silica microspheres are used as the assistant, the catalyst stability is slightly improved compared with the pure molecular sieve catalyst, because the silica has similar physical properties to graphite and has lipophilicity and hydrophobicity, which can promote the discharge of byproduct water to a certain extent. However, due to the spherical structure, the contact area with the molecular sieve surface is very limited, and the molecular sieve- assistant alternating stacking structure cannot be formed, so the catalytic performance is not obviously improved, and the effect is much weaker than that of the flaky graphite, which shows that the morphology and lipophilicity of the assistant are also important.

[0118] As can be seen from Comparative Example 4 and Example 2, when the content of the flaky mesoporous ZSM-5 molecular sieve is too low, the catalytic efficiency of the catalyst rapidly decreases, and the catalyst stability also decreases. The reason may be that the catalyst has limited acid sites, the catalytic efficiency is saturated, which leads to the decrease of the methanol conversion rate, and the generated aromatic hydrocarbon target product is easy to further react with the excess methanol to generate large molecular carbon precursor, which leads to the decrease of the catalyst stability. Therefore, it can be known that the graphite assistant is not the more the better, and the content of the molecular sieve catalyst needs to be in a suitable proportion range, so as to play a role in improving the catalyst stability.

[0119] As can be seen from Comparative Example 5 and Example 3, when the content of the graphite assistant is too low, the catalyst life is not obviously improved, and the reason may be that the reaction performance of the catalyst acid site and the diffusion performance of the mesopore are much higher than the hydrophobic performance of the corresponding graphite, it is difficult to play the structure-property synergistic effect between the graphite assistant and the molecular sieve, and the catalyst stability cannot be further improved.

[0120] As can be seen from Comparative Example 6 and Example 2, when the silicon-aluminum ratio of the molecular sieve is too high, the methanol conversion rate and the aromatic hydrocarbon aviation kerosene selectivity decrease greatly. This is because the methanol aromatization reaction depends on the acid sites of the molecular sieve, and when the silicon-aluminum ratio is too high, the acid sites are insufficient, which leads to the decrease of the methanol conversion rate, and the lack of strong acid sites makes the reaction route deviate, the aromatic hydrocarbon selectivity is significantly reduced, and the alkene selectivity is increased, which makes the catalyst stability improved.

[0121] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation made by using the specification of the present application, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a highly stable catalyst for converting methanol to aromatic hydrocarbons, characterized in that, The method comprises the following steps: S1: adding a silicon source, an aluminum source, tetrapropylammonium hydroxide and urea into water to perform a hydrothermal crystallization reaction, and obtaining a laminar ZSM-5 molecular sieve by performing aerobic calcination on a reaction product; S2: mixing the laminar ZSM-5 molecular sieve and an alkali solution, and then performing heating and stirring, filtering and drying, and performing ammonia exchange to obtain a laminar mesoporous ZSM-5 molecular sieve; the laminar mesoporous ZSM-5 molecular sieve has a silicon-aluminum molar ratio of 20-80, an a-axis length of 1-3 μm, a b-axis length of 50-400 nm and a c-axis length of 300-800 nm; S3: mixing 50-80 % of the laminar mesoporous ZSM-5 molecular sieve and 20-50 % of a graphite aid according to a mass percentage, and then performing ball milling to obtain a catalyst; the catalyst has a structure of alternately stacked molecular sieve-graphite aid, the graphite aid is graphite and / or graphene, and the graphite aid has a water contact angle of > 120°.

2. The method for preparing the highly stable catalyst for methanol-to-aromatics-based jet fuel according to claim 1, characterized in that, In step S1, the silicon source has a molar ratio of silicon element to tetrapropylammonium hydroxide to urea of 1:0.1-0.5:0.1-2.

5.

3. The method of claim 1 or 2, wherein the catalyst is prepared by the steps of: (a) preparing a catalyst precursor by impregnating a support with a solution of a transition metal compound; (b) drying the catalyst precursor; (c) calcining the catalyst precursor; (d) reducing the catalyst precursor; and (e) washing the catalyst with water. In step S1, the silicon source has a molar ratio of silicon element to water of 1:20-33.

5.

4. The method of claim 1, wherein the catalyst is prepared by the steps of: (a) preparing a solution of the catalyst precursor; (b) adding the solution of the catalyst precursor to a solution of the support; (c) drying the mixture; (d) calcining the mixture; (e) reducing the mixture; and (f) drying the mixture. In step S1, the hydrothermal crystallization reaction has a temperature of 120-200 ℃ and a time of 24-80 h.

5. The method for preparing the highly stable catalyst for methanol-to-aromatics-based jet fuel according to claim 1 or 4, characterized in that, In step S1, the aerobic calcination has a temperature of 500-600 ℃ and a time of 3-5 h.

6. The method for preparing the highly stable catalyst for methanol-to-aromatics-based jet fuel according to claim 1, characterized in that, In step S2, the alkali solution has a concentration of 0.1-0.3 M; the heating and stirring have a temperature of 70-90 ℃ and a stirring time of 1-2 h.

7. The method of claim 1 or 6, wherein the catalyst is prepared by the steps of: (a) preparing a solution of the catalyst precursor; (b) adding the solution of the catalyst precursor to the support; (c) drying the catalyst precursor-support mixture; (d) calcining the catalyst precursor-support mixture; and (e) reducing the catalyst precursor-support mixture. In step S2, the ammonia exchange is ion exchange of the laminar ZSM-5 molecular sieve by using an ammonium salt solution.

8. The method of claim 1, wherein the catalyst is prepared by the steps of: (a) preparing a solution of the catalyst precursor; (b) adding the solution of the catalyst precursor to a solution of the support; (c) drying the mixture; (d) calcining the mixture; (e) reducing the mixture; and (f) drying the mixture. In step S3, the ball milling has a rotating speed of 300-600 rpm and a time of 1-3 h.

9. Application of a catalyst prepared by the preparation method of any one of claims 1-8 to methanol-to-aromatics-based aviation kerosene.

10. Use according to claim 9, characterized in that, The reaction conditions of the methanol-to-arene-based aviation kerosene include: under a mixed gas atmosphere of hydrogen and inert gas, the temperature is 350-450 DEG C, the pressure is normal pressure, the methanol space velocity is 0.2-2h -l .

Images