Alkane aromatization method

Abstract

The present invention relates to the technical field of alkane aromatization reactions, and discloses an alkane aromatization method, which comprises: carrying out an aromatization reaction on alkane in the presence of an alkane aromatization catalyst and a diluent to obtain an aromatic hydrocarbon product, wherein the diluent is a molded KL molecular sieve and / or a modified molecular sieve obtained by modifying the molded KL molecular sieve with group IIA metal; the volume ratio of the alkane aromatization catalyst to the diluent is (1-10): 1. The alkane aromatization reaction is carried out in the presence of the alkane aromatization catalyst and the specific diluent, so that compared with the conventional alkane aromatization process, the alkane conversion rate, the aromatic hydrocarbon product selectivity and the hydrogen yield of the alkane aromatization reaction can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of alkane aromatization reaction, and particularly relates to a method for alkane aromatization. Background Art

[0002] The naphtha reforming process is the main way to produce aromatics. However, for traditional bifunctional reforming catalysts, whether it is a platinum-rhenium-based catalyst or a platinum-tin-based catalyst, the activity and selectivity for the dehydrogenation cyclization aromatization reaction of C6-C7 alkanes in naphtha are relatively poor.

[0003] The Pt / KL catalyst has excellent aromatization performance for C6-C7 alkanes, and its activity and aromatics selectivity are much higher than those of platinum-rhenium-based and platinum-tin-based reforming catalysts. The Aromax process of Chevron Corporation and the RZ-100 process of UOP Company are alkane aromatization processes developed based on this catalyst and have been successfully applied industrially. The Pt / KL catalyst is a monofunctional catalyst, and its catalytic mechanism is completely different from that of bifunctional catalysts. Alkanes are adsorbed and closed-loop at the metal center of the catalyst, and then dehydrogenated and aromatized to produce aromatics. The acidic centers of the catalyst support cause side reactions such as cracking and carbon deposition, which will reduce the activity and selectivity of the catalyst. The KL molecular sieve generally contains about 10% of element K, and the presence of K makes the support alkaline. Due to the alkalinity of the KL molecular sieve, the hydrocracking performance of the Pt / KL catalyst is significantly inhibited, the isomerization ability is weakened, and the cyclization dehydrogenation function is greatly enhanced.

[0004] At present, the optimization of the alkane aromatization reaction system catalyzed by Pt / KL mainly focuses on the improvement of the catalyst, such as bimetallic and halogen modification, etc. However, these improvement measures have limited improvement in the alkane aromatization reaction performance. Summary of the Invention

[0005] Aiming at the problems of low conversion rate of raw material alkanes and unsatisfactory selectivity of aromatic hydrocarbon products in the existing alkane aromatization process, the present invention provides a method for alkane aromatization.

[0006] To achieve the above object, the present invention provides a method for alkane aromatization, the method comprising: Performing an aromatization reaction on an alkane in the presence of an alkane aromatization catalyst and a diluent to obtain an aromatic hydrocarbon product; wherein the diluent is the KL molecular sieve after shaping treatment and / or the modified molecular sieve obtained by modifying the KL molecular sieve after shaping treatment with a Group IIA metal; The volume ratio of the alkane aromatization catalyst to the diluent is (1-10):1.

[0007] The method for alkane aromatization provided by the present invention can effectively improve the alkane conversion rate, the selectivity of aromatic hydrocarbon products and the hydrogen production rate in the alkane aromatization reaction (especially for n-hexane) by carrying out the alkane aromatization reaction in the coexistence of an alkane aromatization catalyst and a specific diluent, changing the distribution of reactants and / or products at the microscale. The alkane conversion rate can be ≥90%, while the selectivity of aromatic hydrocarbon products can be ≥80% and the hydrogen production rate can be ≥5%. Description of the Drawings

[0008] Figure 1 It is a schematic diagram of the reactor and the filling condition of the reactor bed used for the aromatization reaction of n-hexane in the examples and comparative examples of the present invention.

[0009] Description of the Reference Numerals I - First reactor II - Second reactor 1 - Catalyst 2 - Quartz sand 3 - Diluent Detailed Description of the Invention The endpoints and any values disclosed in this text are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

[0010] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0011] The present invention provides a method for alkane aromatization, and the method includes:[[]] Carrying out an aromatization reaction on an alkane in the presence of an alkane aromatization catalyst and a diluent to obtain aromatic hydrocarbon products; Wherein, the diluent is the shaped KL molecular sieve and / or the modified molecular sieve obtained by modifying the shaped KL molecular sieve with Group IIA metals; The volume ratio of the alkane aromatization catalyst to the diluent is (1 - 10):1.

[0012] The inventors of the present invention found in the research that, compared with the conventional alkane aromatization process, by carrying out the alkane aromatization reaction in the coexistence of an alkane aromatization catalyst and a specific diluent, the diluent can change the distribution of reactants and / or products at the microscale, increase the number of adsorption active sites of the reactants on the catalyst, and at the same time quickly remove the products from the reaction system, promoting the forward progress of the aromatization reaction, thereby significantly improving the alkane conversion rate, the selectivity of aromatic hydrocarbon products and the hydrogen production rate in the alkane aromatization reaction.

[0013] According to the present invention, preferably, in the method for alkane aromatization provided by the present invention, for the alkane aromatization catalyst, the volume ratio of the diluent is (1 - 2):1, and a comprehensive effect of higher alkane conversion rate, selectivity of aromatic hydrocarbon products and hydrogen yield can be obtained.

[0014] According to the present invention, in the method for alkane aromatization, for the diluent, wherein the shaped KL molecular sieve after shaping treatment refers to an aggregate containing a plurality of KL molecular sieve particles obtained after the KL molecular sieve is aggregated, shaped and calcined. This aggregate has good crystallinity, a large specific surface area and mesoporous specific surface area, and has a uniform mesoporous size distribution. The inventors of the present invention found in the research that by carrying out the alkane aromatization reaction in the co - existence of the alkane aromatization catalyst and the shaped KL molecular sieve after shaping treatment, while the alkane conversion rate can be improved, the selectivity of aromatic hydrocarbon products can be particularly improved.

[0015] According to the present invention, in the method for alkane aromatization, for the diluent, wherein the modified molecular sieve refers to a modified product obtained by modifying the shaped KL molecular sieve with Group IIA metals. Preferably, the modification is carried out by ion exchange.

[0016] According to the present invention, preferably, the Group IIA metal can be selected from at least one of Mg, Ca and Ba, and more preferably Ba.

[0017] The inventors of the present invention found in the research that by carrying out the alkane aromatization reaction in the co - existence of the alkane aromatization catalyst and the above - mentioned modified molecular sieve, while the alkane conversion rate can be improved, the hydrogen yield can be particularly improved.

[0018] According to the present invention, neither the shaped KL molecular sieve after shaping treatment nor the modified molecular sieve contains noble metals in their components. In the present invention, the noble metal refers to a noble metal active component that can catalyze the alkane aromatization reaction, and can be selected from at least one of Pt, Pd and Ru, for example.

[0019] In the present invention, the "not containing noble metals" means that the content of the noble metal element in the shaped KL molecular sieve after shaping treatment and / or the modified molecular sieve is ≤1 ppm.

[0020] According to the present invention, the particle size of the diluent is 0.3 - 1 mm, preferably 0.45 - 0.85 mm. Using the diluent in this particle size range can be equivalent or matched to the particle size of the conventional alkane aromatization catalyst, which is beneficial to the more uniform mixing of the alkane aromatization catalyst and the diluent. At the same time, when the alkane aromatization catalyst and the diluent in this particle size range are mixed and filled in the catalyst bed, it is more beneficial for the reactants to fully contact with the catalyst and for the rapid diffusion of the products.

[0021] In the present invention, the particle size of the diluent refers to the average diameter of the diluent particles.

[0022] According to a preferred embodiment of the present invention, in the method for alkane aromatization, the diluent contains both the shaped KL molecular sieve and the modified molecular sieve after the shaping treatment, and the volume ratio of the shaped KL molecular sieve to the modified molecular sieve is (0.1 - 3):1, preferably (0.5 - 2):1, which can simultaneously achieve the comprehensive effects of high alkane conversion rate, high selectivity of aromatic hydrocarbon products, and high hydrogen yield.

[0023] According to the present invention, in the method for alkane aromatization, preferably, the preparation method of the shaped KL molecular sieve includes: mixing the raw material KL molecular sieve with a shaping aid, then performing a shaping treatment, and subjecting the obtained shaped particles to a first calcination to obtain the shaped KL molecular sieve after the shaping treatment.

[0024] In the present invention, the definition of the raw material KL molecular sieve is relatively broad, and it can be obtained by self - making using known methods or through commercial purchase channels.

[0025] According to the present invention, preferably, the crystal grain size of the raw material KL molecular sieve is 100 - 200 nm, the specific surface area ≥ 280 m 2 / g, the mesoporous specific surface area ≥ 90 m 2 / g, and the mesoporous pore diameter is 15 - 30 nm, which can enable the diluent to bring better aromatization reaction effects.

[0026] In the present invention, the crystal grain size of the molecular sieve is measured by a nano - particle size analyzer.

[0027] In the present invention, the specific surface area of the molecular sieve is measured by the nitrogen physical adsorption - desorption method.

[0028] In the present invention, the mesoporous specific surface area of the molecular sieve is measured by the nitrogen physical adsorption - desorption method.

[0029] In the present invention, the mesoporous pore diameter of the molecular sieve is measured by the nitrogen physical adsorption - desorption method.

[0030] According to the present invention, preferably, the molar ratio of silicon oxide to aluminum oxide in the raw material KL molecular sieve is (6.2 - 6.8):1, and more preferably (6.3 - 6.5):1. Preferably, the content of K (element potassium) in the raw material KL molecular sieve is 9 - 11% by weight, and more preferably 10 - 10.5% by weight. The raw material KL molecular sieve meeting the above silicon - aluminum ratio and K content can enable the diluent to bring better aromatization reaction effects.

[0031] According to the present invention, the shaping aids are defined broadly, and conventional shaping aids in the field of catalyst preparation can be used, including but not limited to sesbania powder, graphite, talc powder, etc. Sesbania powder is preferably used.

[0032] According to the present invention, preferably, the weight ratio of the raw material KL molecular sieve to the shaping aid is (97 - 99):1.

[0033] According to the present invention, the shaping process includes: successively pressing, crushing, and sieving the mixture of the raw material KL molecular sieve and the shaping aid to obtain the shaped particles.

[0034] According to the present invention, preferably, before the first calcination, the shaped particles are dried. The conditions for drying include: the temperature is 100 - 110 °C, and the time is 12 - 24 h.

[0035] According to the present invention, through the first calcination, the particles of the raw material KL molecular sieve are firmly combined to form an aggregate with a stable structure. Preferably, the conditions for the first calcination include: the temperature is 550 - 600 °C, and the time is 5 - 8 h.

[0036] According to the present invention, in the method for alkane aromatization, preferably, the preparation method of the modified molecular sieve includes: performing an ion exchange reaction on the KL molecular sieve after the shaping process with a salt solution containing a Group IIA metal, and performing a second calcination on the obtained solid product to obtain the modified molecular sieve.

[0037] According to the present invention, the salt containing a Group IIA metal can be any water-soluble salt containing a Group IIA metal. Preferably, a nitrate containing a Group IIA metal and / or a chloride containing a Group IIA metal can be used.

[0038] According to the present invention, in the salt component containing a Group IIA metal, preferably, the Group IIA metal can be selected from at least one of Mg, Ca, and Ba, and further preferably Ba.

[0039] According to the present invention, preferably, the concentration of the Group IIA metal ions in the salt solution containing a Group IIA metal is 0.2 - 1 mol / L.

[0040] According to the present invention, in the feed for the ion exchange reaction, preferably, the solid-liquid volume ratio of the KL molecular sieve after the shaping process to the salt solution containing a Group IIA metal is 1:(6 - 12), which is conducive to the more sufficient exchange of the Group IIA metal ions into the KL molecular sieve after the shaping process.

[0041] According to the present invention, in the ion exchange reaction, the number of ion exchange times is not less than 2 times, preferably 2 - 3 times, and the ion exchange time for each time is not less than 4 h, preferably 4 - 6 h, which is beneficial for the more sufficient exchange of Group IIA metal ions into the shaped KL molecular sieve, so that the ion exchange degree of the shaped KL molecular sieve in the ion exchange reaction is not less than 20%, preferably not less than 26%.

[0042] According to the present invention, preferably, before the second calcination, the solid product is dried. The drying conditions of the solid product include: the temperature is 100 - 110 °C and the time is 12 - 24 h.

[0043] According to the present invention, through the second calcination, the binding between the Group IIA metal introduced into the shaped KL molecular sieve by ion exchange and the molecular sieve becomes stronger, making the Group IIA metal more stably present in the shaped KL molecular sieve. Preferably, the conditions of the second calcination include: the temperature is 550 - 600 °C and the time is 5 - 8 h.

[0044] According to the present invention, in the method for alkane aromatization, the alkane is preferably a straight-chain alkane with 6 - 9 carbon atoms, preferably n-hexane and / or n-heptane.

[0045] According to the present invention, in the method for alkane aromatization, the definition of the alkane aromatization catalyst is relatively broad, and any catalyst capable of carrying out the alkane aromatization reaction can be used. Generally, the alkane aromatization catalyst includes a carrier and an active component. Among them, the carrier can use molecular sieves, including but not limited to ZSM-5 molecular sieve, KL molecular sieve, etc., preferably KL molecular sieve; the active component is a noble metal active component, which can be selected from at least one of Pt, Pd, and Ru. In the method for alkane aromatization of the present invention, the alkane aromatization catalyst can be prepared by a known method or obtained through commercial channels, and the present invention has no special limitation on this.

[0046] According to the present invention, in the method for alkane aromatization, the aromatization reaction is preferably carried out in a fixed-bed reactor.

[0047] According to the present invention, in the method for alkane aromatization, preferably, the aromatization reaction conditions include: the mass space velocity of the alkane is 1 - 3 h -1 ; the molar ratio of hydrogen to alkane is (1 - 12):1; the reaction temperature is 430 - 460 °C; the reaction pressure is 0.1 - 1 MPa.

[0048] The present invention will be described in detail below through examples. In the following preparation examples, examples and comparative examples, unless otherwise specified, the materials used are all ordinary commercially available products.

[0049] KL molecular sieve: The crystal grain size is 150 nm, the specific surface area is 285 m 2 / g, the mesoporous specific surface area is 100 m 2 / g, and the mesoporous pore diameter is 20 nm. The molar ratio of silicon oxide to aluminum oxide in this KL molecular sieve is 6.4:1, and the content of K (element potassium) in the KL molecular sieve is 10.2% by weight.

[0050] Preparation Example 1 This preparation example is used to illustrate the preparation of the diluent (1) Mix the KL molecular sieve and sesbania powder evenly according to a weight ratio of 99:1. The obtained mixture is tableted, crushed, and sieved. Take the formed particles with a particle size of 0.5 mm for drying (drying temperature is 110 °C, drying time is 12 h). After drying, calcine at 550 °C for 6 h to obtain the KL molecular sieve after forming treatment; (2) Immerse a part of the above-prepared KL molecular sieve after forming treatment in an aqueous Ba(NO3)2 solution (where the concentration of Ba 2 + is 0.6 mol / L) for an ion exchange reaction. The solid-liquid volume ratio is 1:10, and the ion exchange is carried out 2 times. Each ion exchange time is 4 h, and the ion exchange degree is 26%; Dry the solid product obtained after the ion exchange reaction (drying temperature is 110 °C, drying time is 12 h), and then calcine at 550 °C for 6 h to obtain the modified molecular sieve; (3) Uniformly mix the above-prepared KL molecular sieve after forming treatment and the modified molecular sieve according to a volume ratio of 0.5:1 to obtain a diluent (denoted as A1, and the particle size of diluent A1 is 0.5 mm).

[0051] Preparation Example 2 This preparation example is used to illustrate the preparation of the diluent (1) Mix the KL molecular sieve and sesbania powder evenly according to a weight ratio of 99:1. The obtained mixture is tableted, crushed, and sieved. Take the formed particles with a particle size of 0.5 mm for drying (drying temperature is 110 °C, drying time is 12 h). After drying, calcine at 550 °C for 6 h to obtain the KL molecular sieve after forming treatment; (2) Immerse a part of the above-prepared KL molecular sieve after forming treatment in an aqueous Ba(NO3)2 solution (where the concentration of Ba 2 + is 0.6 mol / L) for an ion exchange reaction. The solid-liquid volume ratio is 1:10, and the ion exchange is carried out 2 times. Each ion exchange time is 4 h, and the ion exchange degree is 26%; The solid product obtained after the ion exchange reaction was dried (drying temperature: 110 °C, drying time: 12 h), and then calcined at 550 °C for 6 h to obtain the modified molecular sieve; (3)The above-mentioned shaped KL molecular sieve and the modified molecular sieve were uniformly mixed at a volume ratio of 2:1 to obtain a diluent (denoted as A2, and the particle size of the diluent A2 was 0.5 mm).

[0052] Preparation Example 3 This preparation example is used to illustrate the preparation of the diluent According to the method of Preparation Example 2, the difference is that in step (3), the shaped KL molecular sieve and the modified molecular sieve were uniformly mixed at a volume ratio of 3:1, and other steps and conditions were the same as those in Preparation Example 2 to obtain a diluent (denoted as A3, and the particle size of the diluent A3 was 0.5 mm).

[0053] Preparation Example 4 This preparation example is used to illustrate the preparation of the diluent According to the method of Preparation Example 2, the difference is that in step (3), the shaped KL molecular sieve and the modified molecular sieve were uniformly mixed at a volume ratio of 0.1:1, and other steps and conditions were the same as those in Preparation Example 2 to obtain a diluent (denoted as A4, and the particle size of the diluent A4 was 0.5 mm).

[0054] Preparation Example 5 This preparation example is used to illustrate the preparation of the diluent According to the method of Preparation Example 4, the difference is that in step (2), the solid-liquid volume ratio was 1:8, the ion exchange was carried out 3 times, the ion exchange time was 4 h each time, and the ion exchange degree was 30%. Other steps and conditions were the same as those in Preparation Example 4 to obtain a diluent (denoted as A5, and the particle size of the diluent A5 was 0.5 mm).

[0055] Preparation Example 6 This preparation example is used to illustrate the preparation of the diluent According to the method of Preparation Example 4, the difference is that in step (2), the Ba(NO3)2 aqueous solution was replaced with a Ca(NO3)2 aqueous solution (where the concentration of Ca 2+ was 0.6 mol / L), and the conditions of the ion exchange reaction were kept unchanged. Other steps and conditions were the same as those in Preparation Example 4 to obtain a diluent (denoted as A6, and the particle size of the diluent A6 was 0.5 mm).

[0056] Preparation Example 7 This preparation example is used to illustrate the preparation of the diluent The shaped KL molecular sieve obtained in step (1) of the above Preparation Example 2 was used as a diluent (denoted as A7, and the particle size of the diluent A7 was 0.5 mm).

[0057] Preparation Example 8 This preparation example is used to illustrate the preparation of the diluent. The modified molecular sieve obtained in step (2) of Preparation Example 2 above was used as the diluent (denoted as A8, and the particle size of diluent A8 was 0.5 mm).

[0058] Example 1 This example is used to illustrate the method of alkane aromatization. The alkane aromatization catalyst (prepared by the impregnation method, the carrier of this catalyst was KL molecular sieve, and the supported active component was metal Pt. Based on the total weight of the catalyst, the content of Pt was 0.5 wt%) and the above diluent A1 were mixed at a volume ratio of 1:1 and filled in the catalyst bed of a fixed bed reactor (the bed filling was as shown in the first reactor I in Figure 1 , where represents the catalyst, represents the diluent, and the first reactor I was used for the reaction), and the aromatization reaction of n-hexane was carried out; The reaction process and conditions were as follows: Before the reaction started, the mixture of the alkane aromatization catalyst and diluent A1 was heated to 500 °C at a heating rate of 2 °C / min in a 2% Ar / H2 gas stream (50 mL / min, with Ar as the internal standard), and reduced at this temperature for 2 h; after the reduction was completed, the temperature was lowered to the reaction required temperature, the 2% Ar / H2 gas stream was adjusted to the reaction required flow rate, and a micro-plunger pump was started to inject the raw material n-hexane for the reaction (the mass space velocity of n-hexane was 1 h -1 ; the molar ratio of hydrogen to n-hexane was 12:1; the reaction temperature was 460 °C; the reaction pressure was 0.1 MPa). The products were analyzed online using an Agilent 7890B gas chromatography system, and the n-hexane conversion and the selectivity of the aromatic hydrocarbon products were calculated based on the results of the first chromatographic sampling analysis.

[0059] The reaction results are shown in Table 1.

[0060] Example 2 This example is used to illustrate the method of alkane aromatization. According to the method of Example 1, the difference was that the volume ratio of the alkane aromatization catalyst to diluent A1 was 3:1. Other steps and conditions were the same as those in Example 1.

[0061] The reaction results are shown in Table 1.

[0062] Examples 3 - 9 This example is used to illustrate the method of alkane aromatization. According to the method of Example 1, the difference was that diluent A1 was replaced with an equal volume of diluents A2 - A8 respectively. Other steps and conditions were the same as those in Example 1.

[0063] The reaction results are shown in Table 1.

[0064] Comparative Example 1 According to the method of Example 2, the difference is that the volume ratio of the alkane aromatization catalyst to diluent A1 is 11:1. Other steps and conditions are the same as those in Example 2.

[0065] The reaction results are shown in Table 1.

[0066] Comparative Example 2 According to the method of Example 2, the difference is that diluent A1 is replaced with an equal volume of quartz sand (the bed filling is as shown in the second reactor II in Figure 1 , where represents the catalyst, represents the quartz sand, and the reaction is carried out using the second reactor II). Other steps and conditions are the same as those in Example 2.

[0067] The reaction results are shown in Table 1.

[0068] Table 1

[0069] As can be seen from Table 1, by using the alkane aromatization method of the present invention, through carrying out the alkane aromatization reaction in the co - presence of an alkane aromatization catalyst and a specific diluent in a certain proportion, it can significantly improve the performance of the alkane aromatization reaction. The alkane conversion rate can reach not less than 90%, the selectivity of the aromatic hydrocarbon product is not less than 80%, and the hydrogen production rate is not less than 5%. In addition, the amount of the diluent in Comparative Example 1 is relatively low, and the diluent used in Comparative Example 2 does not adopt the diluent in the method of the present invention, and the reaction effects are all inferior to those of Examples 1 - 9.

[0070] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for alkane aromatization, characterized in that The method includes: In the presence of an alkane aromatization catalyst and a diluent, subjecting an alkane to an aromatization reaction to obtain an aromatic hydrocarbon product; Wherein, the diluent is the shaped KL molecular sieve and / or the modified molecular sieve obtained by modifying the shaped KL molecular sieve with a Group IIA metal; The volume ratio of the alkane aromatization catalyst to the diluent is (1 - 10):

1.

2. The method for alkane aromatization according to claim 1, wherein The volume ratio of the alkane aromatization catalyst to the diluent is (1 - 2):

1.

3. The method for alkane aromatization according to claim 2, wherein, The volume ratio of the shaped KL molecular sieve to the modified molecular sieve is (0.1 - 3):

1.

4. The method for alkane aromatization according to any one of claims 1-3, wherein The particle size of the diluent is 0.3 - 1 mm.

5. The method for alkane aromatization according to any one of claims 1-3, wherein, The preparation method of the shaped KL molecular sieve includes: mixing the raw material KL molecular sieve with a shaping aid, then performing shaping treatment, and subjecting the obtained shaped particles to a first calcination to obtain the shaped KL molecular sieve; And / or, the preparation method of the modified molecular sieve includes: performing an ion exchange reaction on the shaped KL molecular sieve with a salt solution containing a Group IIA metal, and subjecting the obtained solid product to a second calcination to obtain the modified molecular sieve.

6. The method for alkane aromatization according to claim 4, wherein The preparation method of the shaped KL molecular sieve includes: mixing the raw material KL molecular sieve with a shaping aid, then performing shaping treatment, and subjecting the obtained shaped particles to a first calcination to obtain the shaped KL molecular sieve; And / or, the preparation method of the modified molecular sieve includes: performing an ion exchange reaction on the shaped KL molecular sieve with a salt solution containing a Group IIA metal, and subjecting the obtained solid product to a second calcination to obtain the modified molecular sieve.

7. The method for alkane aromatization according to claim 5, wherein The crystal grain size of the raw material KL molecular sieve is 100 - 200 nm, the specific surface area ≥ 280 m 2 / g, the mesoporous specific surface area ≥ 90 m 2 / g, and the mesoporous pore diameter is 15 - 30 nm; And / or, the molar ratio of silicon oxide to aluminum oxide in the raw material KL molecular sieve is (6.2 - 6.8):

1.

8. The method for alkane aromatization according to claim 6, wherein, The crystal grain size of the raw material KL molecular sieve is 100 - 200 nm, the specific surface area ≥ 280 m 2 / g, the mesoporous specific surface area ≥ 90 m 2 / g, and the mesoporous pore diameter is 15 - 30 nm; And / or, the molar ratio of silicon oxide to aluminum oxide in the raw material KL molecular sieve is (6.2 - 6.8):

1.

9. The method for alkane aromatization according to claim 5, wherein The weight ratio of the raw material KL molecular sieve to the shaping aid is (97 - 99):1; And / or, the conditions of the first calcination include: the temperature is 550 - 600 °C, and the time is 5 - 8 h.

10. The method for alkane aromatization according to any one of claims 6-8, wherein, The weight ratio of the raw material KL molecular sieve to the shaping aid is (97 - 99):1; And / or, the conditions of the first calcination include: the temperature is 550 - 600 °C, and the time is 5 - 8 h.

11. The method for alkane aromatization according to claim 5, wherein, The salt containing a Group IIA metal is selected from the nitrate containing a Group IIA metal and / or the chloride containing a Group IIA metal; And / or, the Group IIA metal is selected from at least one of Mg, Ca, and Ba.

12. The method for alkane aromatization according to any one of claims 6-8, wherein, The salt containing a Group IIA metal is selected from the nitrate containing a Group IIA metal and / or the chloride containing a Group IIA metal; And / or, the Group IIA metal is selected from at least one of Mg, Ca, and Ba.

13. The method for alkane aromatization according to claim 11, wherein, The concentration of the Group IIA metal ions in the salt solution containing a Group IIA metal is 0.2 - 1 mol / L; And / or, the solid-liquid volume ratio of the shaped KL molecular sieve to the salt solution containing a Group IIA metal is 1:(6 - 12); And / or, the ion exchange degree of the shaped KL molecular sieve in the ion exchange reaction is not less than 20%; And / or, the conditions of the second calcination include: the temperature is 550 - 600 °C, and the time is 5 - 8 h.

14. The method for alkane aromatization according to claim 12, wherein, The concentration of Group IIA metal ions in the salt solution containing Group IIA metals is 0.2 - 1 mol / L; and / or, for the shaped KL molecular sieve: the solid-liquid volume ratio of the salt solution containing Group IIA metals is 1:(6 - 12); and / or, the ion exchange degree of the shaped KL molecular sieve in the ion exchange reaction is not less than 20%; and / or, the conditions for the second calcination include: the temperature is 550 - 600 °C and the time is 5 - 8 h.

15. The method for alkane aromatization according to any one of claims 1-3, 6-9, 11, 13-14, wherein, The alkane is a straight-chain alkane with 6 - 9 carbon atoms; And / or, the aromatization reaction conditions include: the mass hourly space velocity of the alkane is 1-3 h -1 , the molar ratio of hydrogen to alkane is (1-12):1, the reaction temperature is 430-460 °C, and the reaction pressure is 0.1-1 MPa.

16. The method for alkane aromatization according to claim 4, wherein, The alkane is a straight-chain alkane with 6 - 9 carbon atoms; And / or, the aromatization reaction conditions include: the mass hourly space velocity of the alkane is 1-3 h -1 , the molar ratio of hydrogen to alkane is (1-12):1, the reaction temperature is 430-460 °C, and the reaction pressure is 0.1-1 MPa.

17. The method for alkane aromatization according to claim 5, wherein The alkane is a straight-chain alkane with 6 - 9 carbon atoms; And / or, the aromatization reaction conditions include: the mass hourly space velocity of the alkane is 1-3 h -1 , the molar ratio of hydrogen to alkane is (1-12):1, the reaction temperature is 430-460 °C, and the reaction pressure is 0.1-1 MPa.

18. The method for alkane aromatization according to claim 10, wherein The alkane is a straight-chain alkane with 6 - 9 carbon atoms; And / or, the aromatization reaction conditions include: the mass hourly space velocity of the alkane is 1-3 h -1 , the molar ratio of hydrogen to alkane is (1-12):1, the reaction temperature is 430-460 °C, and the reaction pressure is 0.1-1 MPa.

19. The method for alkane aromatization according to claim 12, wherein, The alkane is a straight-chain alkane with 6 - 9 carbon atoms; And / or, the aromatization reaction conditions include: the mass space velocity of the alkane is 1-3 h -1 , the molar ratio of hydrogen to alkane is (1-12):1, the reaction temperature is 430-460 °C, and the reaction pressure is 0.1-1 MPa.

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