An aromatization catalyst, a method for preparing the same, and a method for preparing aromatic hydrocarbons by catalyzing the coupling aromatization of propane and dimethyl ether

Abstract

The application provides an aromatization catalyst, a preparation method thereof and a method for preparing aromatic hydrocarbons by catalyzing coupling aromatization of propane and dimethyl ether. The catalyst comprises a HZSM-5 molecular sieve carrier and a Ga2O3 active component; Ga accounts for 0.5-5.0% of the mass of the carrier. The preparation method is as follows: mixing a molecular sieve template agent, a silicon source, an aluminum source and water, carrying out hydrothermal treatment, drying, and calcining to obtain a ZSM-5 molecular sieve, carrying out ion exchange by immersing the ZSM-5 molecular sieve in an ammonium nitrate aqueous solution, and then drying and calcining to obtain a HZSM-5 molecular sieve; carrying out impregnation in a gallium nitrate aqueous solution, and then drying and calcining, so as to obtain the catalyst. The catalyst is pretreated at high temperature under an inert atmosphere, and then propane and dimethyl ether are introduced to carry out the coupling aromatization at a reaction temperature.

Description

Technical Field

[0001] This invention relates to the field of alkane aromatization reactions, and more particularly to an aromatization catalyst, its preparation method, and a method for catalyzing the coupled aromatization of propane and dimethyl ether to prepare aromatics. Background Technology

[0002] Aromatic hydrocarbons such as benzene, toluene, and xylene are important intermediates in petrochemical products, playing a vital role not only in fine chemicals and petrochemicals but also as additives to effectively increase the octane number of gasoline. Indirect liquefaction technology (Fischer-Tropsch synthesis), which converts coal into liquid fuels via syngas, enables the clean and efficient utilization of coal. Fischer-Tropsch synthesis products contain approximately 10 wt% C3-C4 low-carbon alkanes, whose applications are typically limited to residential heating systems and stove fuel, resulting in low utilization value. Converting propane into aromatics can not only serve as a gasoline blending component to increase the octane number of Fischer-Tropsch products but can also be further converted into aviation kerosene components and high-molecular monomers, improving the techno-economic viability of Fischer-Tropsch synthesis.

[0003] Dimethyl ether (a methanol dehydration product), another important coal chemical product, can also be converted into aromatics (MTA) under relatively mild conditions (450-480℃). However, since the aromatization of dimethyl ether is a strongly exothermic reaction, the heat released during the reaction will cause the catalyst to deactivate rapidly, making the technical and economic efficiency of this process not ideal.

[0004] Patent CN107983402A discloses a catalyst with the following composition: 1-2% zinc oxide, 0.1-0.5% gallium oxide, 2-5% molybdenum oxide, 2-4% iron oxide, 0.3-1% rare earth mixed metal oxides, 0.2-0.7% noble metal mixed oxides, and 0.6-1.5% other transition metal mixed oxides. The support is ZSM-5 molecular sieve. This catalyst catalyzes propane aromatization at 400-600℃, achieving a propane conversion of 12-25% and an aromatic selectivity of 23-39%. Patent CN1938245N discloses a Pt / Ga-ZSM-5 molecular sieve catalyst used to catalyze the aromatization of C2-C6 alkanes, achieving a propane conversion of 27-55% and an aromatic selectivity of 28-50%. The aforementioned and most current propane aromatization catalysts involve the use of precious metals, which increases the cost of catalyst preparation. Furthermore, precious metals, especially Pt-based catalysts, are prone to Pt sintering and agglomeration and severe carbon deposition at high temperatures, affecting the catalyst's lifespan.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an aromatization catalyst, its preparation method, and a method for catalyzing the coupled aromatization of propane and dimethyl ether to prepare aromatics. By preparing a Ga2O3 / HZSM-5 catalyst, which is used to catalyze the coupled aromatization reaction of propane and dimethyl ether, the catalyst exhibits high selectivity and high stability. It can improve the selectivity of the target product at low temperatures and shows good single-pass conversion. At the same time, the coupling of the endothermic propane aromatization and the exothermic dimethyl ether aromatization is beneficial to the synergistic effect of the heat effects of the two reactions, thereby reducing energy consumption and simplifying the process.

[0007] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0008] In a first aspect, the present invention provides an aromatization catalyst, comprising a support and an active component supported on the support; wherein the support is an HZSM-5 molecular sieve having an MFI topology, and the active component is Ga2O3 nanoparticles.

[0009] The Ga element in the active component accounts for 0.5 to 5.0% of the mass of the carrier.

[0010] Secondly, the present invention also provides a method for preparing the aromatization catalyst, comprising the following steps:

[0011] S1: Mix the molecular sieve template agent, silicon source, aluminum source and water, and stir until homogeneous;

[0012] S2: The product from step S1 is subjected to hydrothermal treatment, followed by centrifugation, washing, first drying, and first calcination to obtain ZSM-5 molecular sieve;

[0013] S3: The ZSM-5 molecular sieve is immersed in an ammonium nitrate aqueous solution for ion exchange, followed by centrifugation, washing, second drying, and second calcination to obtain HZSM-5 molecular sieve;

[0014] S4: The HZSM-5 molecular sieve is impregnated in an aqueous gallium nitrate solution, followed by a third drying and a third calcination to obtain the Ga2O3 / HZSM-5 catalyst.

[0015] Thirdly, the present invention also provides a method for preparing aromatic hydrocarbons by catalyzing the coupled aromatization of propane and dimethyl ether using the aromatization catalyst described above: the aromatization catalyst is pretreated at high temperature under an inert atmosphere, and then propane and dimethyl ether are introduced at the reaction temperature to carry out the coupled aromatization.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] (1) The aromatization catalyst provided by the present invention and its application in the coupled aromatization reaction of dimethyl ether and propane can achieve a mild conversion of low-carbon alkanes and improve the technical and economic efficiency of producing aromatics from dimethyl ether.

[0018] (2) Coupling the endothermic propane aromatization and the exothermic dimethyl ether aromatization is beneficial to the synergistic effect of the heat of reaction of the two, thereby reducing energy consumption and simplifying the process.

[0019] (3) The aromatization catalyst provided by the present invention avoids the use of precious metals, reduces the cost of industrial catalysts, and the catalyst preparation method has the characteristics of strong operability, good economy and stable properties. At the same time, it can be repeatedly recycled and regenerated, which is very suitable for industrial production and has high industrialization value. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0021] Figure 1 This is a schematic diagram of the XRD crystal form of the aromatization catalyst in Example 1 of this application.

[0022] Figure 2 This is a SEM image of the aromatization catalyst of Example 1 of this application. Detailed Implementation

[0023] As used in this article:

[0024] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0025] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0026] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0027] In these embodiments, unless otherwise specified, all parts and percentages are by weight. Raw material ratios not specified in this invention are for mixing in any proportion.

[0028] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0029] This invention provides an aromatization catalyst, comprising a support and an active component supported on the support; the support is an HZSM-5 molecular sieve with an MFI topology, and the active component is Ga2O3 nanoparticles; the mass of Ga in the active component accounts for 0.5 to 5.0% of the mass of the support.

[0030] This invention also provides a method for preparing the aromatization catalyst, comprising the following steps:

[0031] S1: Mix the molecular sieve template agent, silicon source, aluminum source and water, and stir until homogeneous.

[0032] In some optional embodiments, the molecular sieve template agent includes one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, or tetrabutylammonium hydroxide, which can synthesize molecular sieves with MFI topology.

[0033] In some optional embodiments, the silicon source is one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, butyl orthosilicate, silicon dioxide, or sodium silicate.

[0034] In some optional embodiments, the aluminum source is one or more of aluminum chloride, aluminum oxide, aluminum nitrate, or sodium aluminate.

[0035] In some preferred embodiments, the molar ratio of the molecular sieve template agent, silicon source, aluminum source and water is (36-42):(90-110):(1.5-4):(2600-4400).

[0036] In some preferred embodiments, the silicon source and the aluminum source are in a molar ratio of silicon to aluminum of (10-40):1.

[0037] In some preferred embodiments, the stirring temperature is 20–50°C, and the stirring time is 2–10 h.

[0038] In some alternative embodiments, anhydrous ethanol may be added during the mixing process.

[0039] S2: The product from step S1 is subjected to hydrothermal treatment, followed by centrifugation, washing, first drying, and first calcination to obtain ZSM-5 molecular sieve.

[0040] In some preferred embodiments, the temperature of the hydrothermal treatment is 150–210°C, and the duration of the hydrothermal treatment is 72–192 h.

[0041] In some preferred embodiments, the temperature of the first drying is 100–150°C.

[0042] In some preferred embodiments, the temperature of the first calcination is 450–650°C, and the calcination time is 5–15 hours.

[0043] S3: The ZSM-5 molecular sieve is immersed in an ammonium nitrate aqueous solution for ion exchange, followed by centrifugation, washing, second drying, and second calcination to obtain HZSM-5 molecular sieve.

[0044] In some preferred embodiments, the mass ratio of the ZSM-5 molecular sieve to the ammonium nitrate aqueous solution is 1:(30-40).

[0045] In some preferred embodiments, the concentration of the ammonium nitrate aqueous solution is 0.5–2.0 mol / L.

[0046] In some preferred embodiments, the ion exchange temperature is 70–90°C, and the ion exchange time is 8–16 h.

[0047] In some preferred embodiments, the temperature of the second drying is 100–150°C.

[0048] In some preferred embodiments, the second calcination temperature is 450–600°C, and the second calcination time is 5–15 hours.

[0049] S4: The HZSM-5 molecular sieve is impregnated in an aqueous gallium nitrate solution, followed by a third drying and a third calcination to obtain the Ga2O3 / HZSM-5 catalyst.

[0050] In some preferred embodiments, the immersion temperature is 25–50°C, and the immersion time is 4–10 hours.

[0051] In some preferred embodiments, the temperature of the third drying is 100–150°C.

[0052] In some preferred embodiments, the temperature of the third calcination is 400–600°C, and the time of the third calcination is 2–10 hours.

[0053] In some more preferred embodiments, the gallium nitrate aqueous solution also contains ammonium nitrate, and the molar ratio of ammonium nitrate to gallium nitrate is (3-6):1; the impregnation temperature is 45-50°C.

[0054] This invention also provides a method for preparing aromatic hydrocarbons by catalyzing the coupled aromatization of propane and dimethyl ether using the aromatization catalyst described above: the aromatization catalyst is pretreated at a high temperature of 500-600°C for 1-5 hours under an inert atmosphere, and then propane and dimethyl ether are introduced at the reaction temperature to carry out the coupled aromatization.

[0055] In some preferred embodiments, the coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

[0056] In some preferred embodiments, the reaction temperature for the coupled aromatization is 300–450°C, and the reaction pressure is 0.1–0.5 MPa.

[0057] In some preferred embodiments, the molar ratio of propane to dimethyl ether is (5-25):1;

[0058] In some preferred embodiments, the feed mass hourly space velocity (WHSV) of the propane and dimethyl ether mixture is 0.2–1.0 h⁻¹. -1 ;

[0059] In some preferred embodiments, the regeneration temperature is 600–800°C, and the regeneration pressure is 0.1–0.5 MPa.

[0060] In this embodiment of the invention, the product analysis method uses Agilent chromatography. The specific detection methods for aromatics and other products are as follows:

[0061] Column temperature: Hold at 40℃ for 5 min, increase to 150℃ at 3℃ / min, hold for 0 min, then increase at 5℃ / min.

[0062] Heat to 200℃ at a rate of 0 min, hold for 0 min; Inlet temperature: 250℃; Detector temperature: 250℃.

[0063] Septum purge gas flow rate: 3 ml / min; column flow rate (N2): 0.5 ml / min; split injection, split ratio 10:1; hydrogen flow rate: 40 ml / min; air flow rate: 350 ml / min;

[0064] Exhaust gas purging flow rate: 25 ml / min.

[0065] Example 1

[0066] A method for preparing an aromatization catalyst:

[0067] (1) Mix 65.28g of tetrapropylammonium hydroxide solution (mass fraction of 25wt%), 45.20g of tetraethyl orthosilicate, 2.72g of aluminum nitrate, 10g of anhydrous ethanol and 114g of water in a hydrothermal reactor and stir at 30℃ for 6h to obtain a mixed slurry.

[0068] (2) The mixed slurry was hydrothermally treated at 175°C for 144 hours, centrifuged, washed, and dried at 120°C for 12 hours to obtain a white dry powder.

[0069] (3) The white dry powder is calcined at 560°C for 12 hours in air to obtain ZSM-5 molecular sieve.

[0070] (4) Take 5g of the ZSM-5 molecular sieve and immerse it in 200g of ammonium nitrate aqueous solution (1mol / L). Perform ion exchange at 80℃ for 12h, then centrifuge, wash, and dry at 130℃ for 6h to obtain solid powder.

[0071] (5) The solid powder obtained in step (4) is calcined at 580°C for 8 hours in an air atmosphere to obtain HZSM-5 molecular sieve.

[0072] (6) Take 5g of the HZSM-5 molecular sieve and immerse it in 50g of gallium nitrate aqueous solution (0.01mol / L). Stir and immerse at 500rpm for 6h at room temperature, and then dry at 110℃ for 10h to obtain solid powder.

[0073] (7) The solid powder obtained in step (6) is calcined at 550°C for 6 hours in air to obtain the aromatized catalyst, which has the composition of 1.5 wt% Ga and 98.5 wt% HZSM-5 molecular sieve. Its XRD crystal structure is shown in the figure. Figure 1 As shown, the SEM image is as follows: Figure 2 As shown.

[0074] A coupled aromatization reaction was carried out using 95% propane and 5% dimethyl ether as raw materials and N2 as carrier gas, as detailed below:

[0075] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 580°C for 3 hours. The temperature was then lowered to 400°C. The feed rates of N2 and 95% propane + 5% dimethyl ether were adjusted, with a molar ratio of N2, propane, and dimethyl ether of 30:13:1. The reactor pressure was 0.15 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0076] The coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

[0077] Example 2

[0078] A method for preparing an aromatization catalyst:

[0079] (1) Mix 65.28g of tetrapropylammonium hydroxide solution (mass fraction of 25wt%), 45.20g of tetraethyl orthosilicate, 2.72g of aluminum nitrate, 10g of anhydrous ethanol and 114g of water in a hydrothermal reactor and stir at 30℃ for 6h to obtain a mixed slurry.

[0080] (2) The mixed slurry was hydrothermally treated at 170°C for 168 hours, centrifuged, washed, and dried at 110°C for 10 hours to obtain a white dry powder.

[0081] (3) The white dry powder is calcined at 580°C for 8 hours in air to obtain ZSM-5 molecular sieve.

[0082] (4) Take 5g of the ZSM-5 molecular sieve and immerse it in 200g of ammonium nitrate aqueous solution (1mol / L). Perform ion exchange at 75℃ for 15h, then centrifuge, wash, and dry at 120℃ for 12h to obtain solid powder.

[0083] (5) The solid powder obtained in step (4) is calcined at 560°C for 10 hours in air to obtain HZSM-5 molecular sieve.

[0084] (6) Take 5g of the HZSM-5 molecular sieve and immerse it in 50g of gallium nitrate aqueous solution (0.03mol / L). Let it stand at room temperature for 8h and then dry it at 120℃ for 15h to obtain solid powder.

[0085] (7) The solid powder obtained in step (6) is calcined at 560°C for 8 hours in an air atmosphere to obtain the aromatization catalyst, which has the composition of 2.0 wt% Ga and 98 wt% HZSM-5 molecular sieve.

[0086] A coupled aromatization reaction was carried out using 95% propane and 5% dimethyl ether as raw materials and N2 as carrier gas, as detailed below:

[0087] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 570°C for 5 hours. The temperature was then lowered to a reaction temperature of 450°C. The feed rates of N2 and 95% propane + 5% dimethyl ether were adjusted, with a molar ratio of N2, propane, and dimethyl ether of 30:13:1. The reactor pressure was 0.1 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0088] The coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

[0089] Example 3

[0090] The preparation method of the aromatization catalyst is the same as that in Example 1.

[0091] A coupled aromatization reaction was carried out using 97% propane and 3% dimethyl ether as raw materials and N2 as carrier gas, as detailed below:

[0092] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 580°C for 3 hours. The temperature was then lowered to 400°C. The feed rates of N2 and 97% propane + 3% dimethyl ether were adjusted, with a molar ratio of N2, propane, and dimethyl ether of 56:22:1. The reactor pressure was 0.15 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0093] The coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

[0094] Example 4

[0095] The preparation method of the aromatization catalyst is the same as that in Example 2.

[0096] A coupled aromatization reaction was carried out using 97% propane and 3% dimethyl ether as raw materials and N2 as carrier gas, as detailed below:

[0097] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 580°C for 3 hours. The temperature was then lowered to a reaction temperature of 450°C. The feed rates of N2 and 97% propane + 3% dimethyl ether were adjusted, with a molar ratio of N2, propane, and dimethyl ether of 56:22:1. The reactor pressure was 0.15 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0098] The coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

[0099] Example 5

[0100] The method for preparing the aromatization catalyst differs from that in Example 2 in that 3.34 g of sodium hydroxide is added in step (1).

[0101] The coupled aromatization reaction was carried out using 95% propane and 5% dimethyl ether as raw materials and N2 as carrier gas. The reaction conditions and evaluation methods were the same as in Example 2.

[0102] Example 6

[0103] The method for preparing the aromatization catalyst differs from that in Example 2 in that 6.68g of sodium hydroxide is added in step (1).

[0104] The coupled aromatization reaction was carried out using 95% propane and 5% dimethyl ether as raw materials and N2 as carrier gas. The reaction conditions and evaluation methods were the same as in Example 2.

[0105] Example 7

[0106] The method for preparing the aromatization catalyst differs from that in Example 2 in that 10.02g of sodium hydroxide is added in step (1).

[0107] The coupled aromatization reaction was carried out using 95% propane and 5% dimethyl ether as raw materials and N2 as carrier gas. The reaction conditions and evaluation methods were the same as in Example 2.

[0108] Example 8

[0109] The method for preparing the aromatization catalyst differs from that in Example 2 in that, in step (6), 5g of the HZSM-5 molecular sieve is immersed in 50g of gallium nitrate aqueous solution (wherein, the concentration of gallium nitrate is 0.03mol / L and the concentration of ammonium nitrate is 0.1mol / L), and then allowed to stand for 8h at 50℃, and then dried at 120℃ for 15h to obtain solid powder.

[0110] Example 9

[0111] The method for preparing the aromatization catalyst differs from that in Example 2 in that, in step (6), 5g of the HZSM-5 molecular sieve is immersed in 50g of gallium nitrate aqueous solution (wherein, the concentration of gallium nitrate is 0.03mol / L and the concentration of ammonium nitrate is 0.15mol / L), and then allowed to stand for 8h at 45℃, and then dried at 120℃ for 15h to obtain solid powder.

[0112] Comparative Example 1

[0113] The preparation method of the aromatization catalyst is the same as that in Example 1.

[0114] A coupled aromatization reaction is carried out using propane and N2 as raw materials and N2 as carrier gas, as detailed below:

[0115] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 580°C for 3 hours. The temperature was then lowered to a reaction temperature of 400°C. The N2 and propane feed rates were adjusted to a molar ratio of 5:2. The reactor pressure was 0.15 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0116] Comparative Example 2

[0117] The preparation method of the aromatization catalyst is the same as that in Example 1.

[0118] Nitrogen gas was continuously introduced into a fixed-bed reactor containing 3g of the aromatization catalyst, and the reactor was pretreated at 580°C for 3 hours. The temperature was then lowered to 400°C. The feed rates of N2 and dimethyl ether were adjusted to a molar ratio of 5:3. The reactor pressure was 0.15 MPa, and the mass hourly space velocity (HSV) of the mixed gas feed was 0.3 h⁻¹. -1 The reaction products were obtained and analyzed online by gas chromatography.

[0119] Table 1. Evaluation results of catalysts and coupled aromatization reactions in Examples 1-9 and Comparative Examples 1-2.

[0120]

[0121] As can be seen from the test results of the various embodiments and comparative examples in Table 1, the aromatization catalyst provided by this invention is suitable for the coupled aromatization reaction of propane and dimethyl ether, exhibiting high catalytic activity, high selectivity, and high stability, and has significant potential for industrial application. Adding Na to the molecular sieve raw material does not have a significant effect, while simultaneously adding ammonium nitrate during gallium nitrate impregnation helps compensate for the activity loss caused by drying and calcination steps after ion exchange, without significantly reducing stability.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. In addition, those skilled in the art can understand that although some embodiments here include certain features included in other embodiments but not other features, the combination of features of different embodiments means that they are within the scope of the present invention and form different embodiments. For example, in the above claims, any one of the claimed embodiments can be used in any combination. The information disclosed in this background section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form implying that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a catalyst for the coupled aromatization of propane and dimethyl ether, characterized in that, Includes the following steps: S1: Mix the molecular sieve template agent, silicon source, aluminum source and water, and stir until homogeneous; S2: The product from step S1 is subjected to hydrothermal treatment, followed by centrifugation, washing, first drying, and first calcination to obtain ZSM-5 molecular sieve; S3: The ZSM-5 molecular sieve is immersed in an ammonium nitrate aqueous solution for ion exchange, followed by centrifugation, washing, second drying, and second calcination to obtain HZSM-5 molecular sieve; S4: The HZSM-5 molecular sieve is impregnated in an aqueous gallium nitrate solution, followed by a third drying and a third calcination to obtain the Ga2O3 / HZSM-5 catalyst; The gallium nitrate aqueous solution also contains ammonium nitrate, and the molar ratio of ammonium nitrate to gallium nitrate is (3~6):

1.

2. The preparation method according to claim 1, characterized in that, Step S1 satisfies one or more of the following conditions: a. The molecular sieve template agent includes one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, or tetrabutylammonium hydroxide; b. The silicon source is one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, silicon dioxide, or sodium silicate; c. The aluminum source is one or more of aluminum chloride, aluminum oxide, aluminum nitrate or sodium aluminate; d. The stirring temperature is 20~50℃, and the stirring time is 2~10h.

3. The preparation method according to claim 1, characterized in that, Step S2 satisfies one or more of the following conditions: e. The temperature of the hydrothermal treatment is 150~210℃, and the time of the hydrothermal treatment is 72~192h; f. The temperature for the first drying step is 100~150℃; g. The temperature of the first roasting is 450~650℃, and the roasting time is 5~15h.

4. The preparation method according to claim 1, characterized in that, Step S3 satisfies one or more of the following conditions: h. The mass ratio of the ZSM-5 molecular sieve to the ammonium nitrate aqueous solution is 1:(30~40); i. The concentration of the ammonium nitrate aqueous solution is 0.5~2.0 mol / L; j. The temperature of the ion exchange is 70~90℃, and the time of the ion exchange is 8~16h; k. The temperature for the second drying is 100~150℃; 1. The second roasting temperature is 450~600℃, and the second roasting time is 5~15h.

5. The preparation method according to claim 1, characterized in that, Step S4 satisfies one or more of the following conditions: m. The immersion temperature is 25~50℃, and the immersion time is 4~10h; n. The temperature of the third drying step is 100~150℃; o. The temperature of the third roasting is 400~600℃, and the time of the third roasting is 2~10h.

6. The preparation method according to any one of claims 1-5, characterized in that, In step S4, the immersion temperature is 45~50℃.

7. A catalyst for catalyzing the coupled aromatization of propane and dimethyl ether, characterized in that, The catalyst is prepared by the preparation method according to any one of claims 1-6; The catalyst for catalyzing the coupled aromatization of propane and dimethyl ether comprises a support and an active component supported on the support; the support is an HZSM-5 molecular sieve with an MFI topology, and the active component is Ga2O3 nanoparticles. The mass of Ga element in the active component accounts for 0.5 to 5.0% of the mass of the carrier.

8. A method for preparing aromatics by coupled aromatization of propane and dimethyl ether using the catalyst of claim 7, characterized in that, The catalyst was pretreated at 500-600°C for 1-5 hours under an inert atmosphere, and then propane and dimethyl ether were introduced at the reaction temperature to carry out the coupled aromatization.

9. The method according to claim 8, characterized in that, The coupled aromatization reaction is carried out alternately in two parallel radial fixed-bed reactors; while one reactor is reacting, the other reactor is regenerating the catalyst.

10. The method according to claim 9, characterized in that, The method satisfies one or more of the following conditions: p. The reaction temperature for the coupled aromatization is 300~450℃, and the reaction pressure is 0.1~0.5MPa; q. The molar ratio of propane to dimethyl ether is (5~25):1; r. The feed mass hourly space velocity (WHSV) of the mixed gas of propane and dimethyl ether is 0.2~1.0 h⁻¹. -1 ; s. The regeneration temperature is 600~800℃, and the regeneration pressure is 0.1~0.5MPa.

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