Modified ZSM-5 molecular sieve and preparation method thereof

Abstract

The invention provides a modified ZSM-5 molecular sieve and a preparation method thereof. The preparation method comprises the following steps: step 1, forming gel from a silicon source, an alkali source, a metal salt solution and cardanol polyoxyethylene ether sulfonate; and step 2, adding a ZSM-5 seed crystal into the gel, and then crystallizing, drying and roasting to obtain the modified ZSM-5 molecular sieve. The molecular sieve prepared by the method does not use a template agent, the synthesis method is simple, the crystallinity is high, and when the molecular sieve is used for catalytic cracking / cracking reaction, the yield of low-carbon olefins in a target product can be improved.

Description

Technical Field

[0001] The invention relates to the field of catalysts, and in particular to a modified ZSM-5 molecular sieve and a preparation method thereof. Background Art

[0002] ZSM-5 molecular sieve is a type of silicate molecular sieve with MFI pore structure, which has been widely used in many fields such as petrochemical, coal chemical and fine chemical. Especially in the field of catalytic cracking / cracking, the unique pore structure of ZSM-5 molecular sieve enables it to selectively catalyze the alkylation, isomerization and aromatization reactions of gasoline components, improve the quality of gasoline products and increase the yield of low-carbon olefins.

[0003] CN101332995A and CN1872415A have developed an in-situ crystallization method for high-content ZSM-5 zeolite, including modified calcination of kaolin and in-situ crystallization of ZSM-5 zeolite. In the modified calcination step, kaolin and modified components are either mechanically mixed into powder or sprayed into balls, and the calcination temperature is preferably 800-1100°C for 2-5 hours. The preparation method requires adding silicon source, aluminum source, template agent and seed crystal to the calcined kaolin at 20-70°C and stirring for 1-5 hours to obtain a uniform gel, and crystallizing at 140-180°C in an autoclave for 10-48 hours to obtain a kaolin-based ZSM-5 zeolite with a zeolite content of 30-80%. The patent believes that under the conditions described in the invention, the stirring method greatly affects the in-situ crystallization. During the static crystallization process, non-in-situ zeolite accounts for a large proportion, and in-situ ZSM-5 may not be generated. Stirring too fast or too slow will directly affect the zeolite content of the crystallized product. The content of kaolin-based ZSM-5 zeolite prepared by the invention can be controlled by adjusting the crystallization reaction conditions and changing the ratio of the binder and the filler. When used as a catalytic cracking additive, the total liquid yield is increased by more than 2 percentage points, and the propylene yield is increased by 1.7 percentage points compared with domestic commercial additives and imported additives.

[0004] U.S. Patent No. 5,472,594 discloses a catalyst containing phosphorus-modified ZSM-5 and Y, wherein the mass ratio of phosphorus-modified ZSM-5 to Y is between 0.005-0.1, the catalyst-to-oil ratio is between 0.10 and 10, the reaction temperature is between 800 and 12,000°C, and the pressure is between 0 and 150 pounds per inch. Under the reaction conditions, the catalytic cracking reaction is carried out, and it is found that the yield of C4-C5 olefins is increased, but the loss of gasoline yield is also reduced.

[0005] U.S. Patent No. 5,380,690 discloses a cracking catalyst for producing more low-carbon olefins, which is composed of 0-70 wt.% clay, 5-99 wt.% inorganic oxides, and 1-50 wt.% molecular sieves. The molecular sieves are composed of 0-25 wt.% REY or high-silicon Y and 75-100 wt.% high-silicon ZSM-5 containing phosphorus and rare earths. Compared with a catalyst using only HZSM-5 molecular sieve as an active component, the catalyst shows better hydrothermal stability and higher C2-C4 low-carbon olefin yield in catalytic cracking reactions.

[0006] US Patent No. 3,758,403 also states that under the reaction conditions of catalytic cracking, using ZSM-5 molecular sieve and REY molecular sieve as catalyst active components has a higher yield of light olefins than using REY molecule alone as the active component.

[0007] In US Pat. No. 4,025,575, H-ZSM-5 zeolite is used as a catalyst to convert low-carbon oxygen-containing compounds into lower olefins ethylene and propylene.

[0008] US Pat. No. 5,367,100 discloses the production of light olefins using a ZSM-5-based zeolite catalyst containing at least 0.7 wt.% phosphorus and at least 0.97 wt.% rare earth elements doped in the structure of the catalyst.

[0009] Chinese patent CN102372555A discloses a method for preparing light olefins by fluidized catalytic cracking of naphtha, using naphtha and water as raw materials, at a reaction temperature of 600-750°C and a weight space velocity of 0.1-2h -1 , under the condition that the weight ratio of water to oil is 0.1-8:1, the raw material contacts with a fluidized bed catalyst to react and generate ethylene and propylene, wherein the catalyst used comprises the following components by weight percentage: a) 15.0-60.0% selected from kaolin; b) 10.0-30.0% selected from at least one of silicon oxide or aluminum oxide; c) 0.5-15.0% selected from at least one of phosphorus, rare earth or alkaline earth element oxides; d) 25.0-70.0% selected from ZSM-5 zeolite with a grain size of 200-1000nm prepared by a directing agent method.

[0010] In summary, the use of modified ZSM-5 molecular sieves to produce low-carbon olefins is one of the research directions of technicians, and improving the crystallization rate during the preparation process, not using templates, and having suitable acidity is one of the research focuses of R&D personnel. Summary of the invention

[0011] The main purpose of the present invention is to provide a modified ZSM-5 molecular sieve and a preparation method thereof, so as to overcome the defects of the modified ZSM-5 molecular sieve preparation process in the prior art, such as low crystallinity, high cost caused by the use of templates, and inappropriate acidity.

[0012] In order to achieve the above object, the present invention provides a method for preparing a modified ZSM-5 molecular sieve, comprising the following steps:

[0013] Step 1, forming a gel with a silicon source, an alkali source, a metal salt solution and cardanol polyoxyethylene ether sulfonate;

[0014] Step 2, adding ZSM-5 seed crystals to the gel, followed by crystallization, drying, and calcination to obtain a modified ZSM-5 molecular sieve;

[0015] Wherein, the metal in the metal salt solution is at least one of iron, titanium and silver.

[0016] The method for preparing the modified ZSM-5 molecular sieve of the present invention, wherein the step of forming a gel in step 1 comprises:

[0017] A silicon source, an alkali source and water are mixed to form a solution A, and the solution A is hydrolyzed for 15 to 40 minutes; a metal salt solution is added to the solution A, and then cardanol polyoxyethylene ether sulfonate is added, and the mixture is stirred to obtain the gel.

[0018] The preparation method of the modified ZSM-5 molecular sieve of the present invention, wherein the silicon source is silica sol, tetraethyl silicate, methyl orthosilicate or water glass; the alkali source is ethylamine or n-butylamine; the cardanol polyoxyethylene ether sulfonate is cardanol polyoxyethylene ether sulfonate sodium, cardanol polyoxyethylene ether sulfonate magnesium or cardanol polyoxyethylene ether sulfonate ammonium.

[0019] The method for preparing a modified ZSM-5 metal salt solution of the present invention, wherein the metal salt in the metal salt solution is at least one of ferric nitrate, ferric chloride, ferric sulfate, titanium nitrate, titanium sulfate, titanium chloride, silver nitrate and silver sulfate.

[0020] The preparation method of the modified ZSM-5 molecular sieve of the present invention, wherein the silicon source is in the form of SiO2, the alkali source is in the form of OH - In terms of ions, the metal salt solution is calculated based on metal cations, the molar ratio of the silicon source, the alkali source, the metal salt solution and water is 1:2-10:0.01-0.05:4-10, and the molar ratio of the cardanol polyoxyethylene ether sulfonate to the silicon source is 0.005-0.03:1.

[0021] The preparation method of the modified ZSM-5 molecular sieve of the present invention, wherein the stirring is carried out at a temperature of 50° C. to 90° C., and the stirring time is 15 to 60 minutes.

[0022] The method for preparing the modified ZSM-5 molecular sieve of the present invention further comprises the step of exchanging the modified ZSM-5 molecular sieve with ammonium ions.

[0023] The preparation method of the modified ZSM-5 molecular sieve of the present invention comprises the following steps: the mass ratio of the added amount of the ZSM-5 seed crystals to the gel is 1:100 to 5:100; the crystallization temperature is 130°C to 170°C, the time is 1h to 3h, and the crystallization method is microwave radiation heating; the drying temperature is 100 to 120°C, and the drying time is 8 to 12h.

[0024] The preparation method of the modified ZSM-5 molecular sieve of the present invention, wherein the synthesis steps of the cardanol polyoxyethylene ether sulfonate are:

[0025] Step a, synthesizing cardanol polyoxyethylene ether by reacting cardanol with ethylene oxide under alkaline conditions;

[0026] Step b, using cardanol polyoxyethylene ether as a raw material, adding tert-butanol base, using alcohol as a solvent, refluxing, then cooling the reaction system to room temperature, adding a sultone compound dropwise, refluxing, cooling, and obtaining cardanol polyoxyethylene ether sulfonate.

[0027] The sultone compound is 1,3-propane sultone and / or 1,4-butane sultone.

[0028] In order to achieve the above object, the present invention also provides a modified ZSM-5 molecular sieve prepared by the above preparation method.

[0029] Beneficial effects of the present invention:

[0030] (1) In the process of preparing the modified ZSM-5 molecular sieve, metal elements such as iron, titanium, and silver are introduced, and the environmentally friendly additive cardanol polyoxyethylene ether sulfonate is added at the same time, and the two act synergistically. During the crystal nucleation and growth process, the solvent interface increases, and a small amount of cardanol polyoxyethylene ether sulfonate is added, which can effectively reduce the surface and interfacial tension of the solution, and is easy to nucleate from the energy point of view, and micelles are formed in the gel. This effect increases the contact and action probability between silicon and metal elements, that is, the crystallization rate is increased by changing the thermodynamic properties of the sol, thereby improving the crystallinity of the modified ZSM-5 molecular sieve. At the same time, the metal elements are successfully introduced into the molecular sieve framework. Due to the presence of metal elements in the molecular sieve, its oxidation is conducive to the generation of positive carbon ions, making the reaction easier to initiate, thereby improving the reaction activity and facilitating the improvement of olefin yield. In addition, the sulfonic acid group in the additive cardanol polyoxyethylene ether sulfonate can effectively neutralize the surface acidity of the molecular sieve, which can improve the reaction selectivity.

[0031] (2) The modified ZSM-5 molecular sieve synthesis process of the present invention adopts the seed method and does not use an organic template agent, which has low cost and avoids environmental pollution caused by the use of an organic template agent. DETAILED DESCRIPTION

[0032] The technical scheme of the present invention is described in detail below. The following implementation modes are implemented on the premise of the technical scheme of the present invention, and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following implementation modes. The structures or experimental methods of specific conditions are not specified in the following implementation modes, and generally conventional conditions are followed.

[0033] The present invention provides a method for preparing a modified ZSM-5 molecular sieve, comprising the following steps:

[0034] Step 1, forming a gel with a silicon source, an alkali source, a metal salt solution and cardanol polyoxyethylene ether sulfonate;

[0035] Step 2, adding ZSM-5 seed crystals into the gel, followed by crystallization, drying and calcination to obtain a modified ZSM-5 molecular sieve.

[0036] The present invention introduces metal elements in the preparation process of modified ZSM-5 molecular sieve, and adds environmentally friendly additive cardanol polyoxyethylene ether sulfonate at the same time, and the two act synergistically. During the crystal nucleation growth process, the solvent interface increases, and a small amount of cardanol polyoxyethylene ether sulfonate is added, which can effectively reduce the surface interfacial tension of the solution, is easy to nucleate from energy, and forms micelles in the gel, and this effect increases the contact and action probability between silicon and the metal elements, that is, by changing the thermodynamic properties of the sol, the crystallization rate is improved, thereby improving the crystallinity of the modified ZSM-5 molecular sieve. At the same time, the metal elements are also successfully introduced into the molecular sieve framework, and due to the presence of metal elements in the molecular sieve, its oxidation is conducive to the generation of positive carbon ions, so that the reaction is more easily triggered, thereby improving the reaction activity, and is conducive to the improvement of olefin yield. In addition, the sulfonic acid group part in the additive cardanol polyoxyethylene ether sulfonate can effectively neutralize the molecular sieve surface acidity, and the reaction selectivity can be improved.

[0037] In one embodiment, the step of forming a gel in step 1 of the present invention comprises:

[0038] A silicon source, an alkali source and water are mixed to form a solution A, and the solution A is hydrolyzed for 15 to 40 minutes; a metal salt solution is added to the solution A, and then cardanol polyoxyethylene ether sulfonate is added, and the mixture is stirred to obtain the gel.

[0039] In one embodiment, the silicon source of the present invention is silica sol, tetraethyl silicate, methyl orthosilicate or water glass; the alkali source is ethylamine or n-butylamine. The metal in the metal salt solution is at least one of iron, titanium and silver, and the metal salt is at least one of ferric nitrate, ferric chloride, ferric sulfate, titanium nitrate, titanium sulfate, titanium chloride, silver nitrate and silver sulfate, preferably silver nitrate. The cardanol polyoxyethylene ether sulfonate is sodium cardanol polyoxyethylene ether sulfonate, magnesium cardanol polyoxyethylene ether sulfonate or ammonium cardanol polyoxyethylene ether sulfonate.

[0040] In one embodiment, the silicon source is in the form of SiO2, and the alkali source is in the form of OH - ions, the metal salt solution is calculated as metal cations, the molar ratio of the silicon source, the alkali source, the metal salt solution and water is 1:2-10:0.01-0.05:4-10, and the molar ratio of the cardanol polyoxyethylene ether sulfonate to the silicon source is 0.005-0.03:1.

[0041] In one embodiment, after adding the cardanol polyoxyethylene ether sulfonate, the present invention is stirred (hydrolyzed) at 50° C. to 90° C. for 15 to 60 minutes to obtain the gel.

[0042] Then, ZSM-5 seed crystals are added into the gel, followed by crystallization, drying and calcination to obtain a modified ZSM-5 molecular sieve.

[0043] In one embodiment, the mass ratio of the added amount of ZSM-5 seed crystals to the gel of the present invention is 1:100 to 5:100. After the seed crystals are added, the mixture is stirred again, then crystallized, cooled to room temperature, centrifugally filtered, washed, dried, and calcined to obtain a modified ZSM-5 molecular sieve.

[0044] In one embodiment, during the preparation of the ZSM-5 molecular sieve of the present invention, the crystallization temperature is 130°C to 170°C, the time is 1h to 3h, the crystallization method is microwave radiation heating; the drying temperature is 100 to 120°C, and the drying time is 8 to 12h. The present invention does not specifically limit the calcination temperature, and the conventional calcination temperature in the art can be used.

[0045] In one embodiment, the obtained modified ZSM-5 molecular sieve needs to be subjected to ammonium ion exchange treatment. Specifically, the ammonium salt, the modified ZSM-5 molecular sieve and the deionized water can be mixed and slurried uniformly according to the weight ratio of ammonium salt: modified ZSM-5 molecular sieve: deionized water = 0.005-1: 1: 1-50, the pH value of the slurry is adjusted to 2.0-6.0, and the exchange is carried out at 40-130° C. for 0.5-4 hours. The ammonium salt can be one of ammonium chloride, ammonium sulfate, ammonium phosphate and ammonium nitrate.

[0046] In one embodiment, the present invention also provides a synthesis step of cardanol polyoxyethylene ether sulfonate, comprising:

[0047] Step a, synthesizing cardanol polyoxyethylene ether by reacting cardanol with ethylene oxide under alkaline conditions;

[0048] Step b, using cardanol polyoxyethylene ether as a raw material, adding tert-butanol base, using alcohol as a solvent, refluxing, then cooling the reaction system to room temperature, adding a sultone compound dropwise, refluxing, cooling, and obtaining cardanol polyoxyethylene ether sulfonate.

[0049] The sultone compound of the present invention is a compound containing a sultone group. In one embodiment, the sultone compound is 1,3-propane sultone and / or 1,4-butane sultone.

[0050] In one embodiment, the mass ratio of cardanol to ethylene oxide is 1:10-1:40.

[0051] In one embodiment, the synthesis step of cardanol polyoxyethylene ether sulfonate can also be: using cardanol as a raw material, synthesizing cardanol polyoxyethylene ether with ethylene oxide under alkaline conditions; under argon protection, in a three-necked flask, using cardanol polyoxyethylene ether (EON value: n≈5, 6, 10, 12, 18) as a raw material, sodium tert-butoxide as a base, and anhydrous ethanol as a solvent, reflux for 30 minutes, the reaction system is cooled to room temperature, 1,3-propane sultone or 1,4-butane sultone is slowly added dropwise, refluxed, cooled, and excess ethanol is removed by vacuum distillation, petroleum ether is added, and grinding is performed to obtain a white solid, centrifugation is performed, and vacuum drying is performed to obtain the final product, which is a white, hygroscopic solid cardanol polyoxyethylene ether sodium sulfonate.

[0052] In one embodiment, the solvent alcohol may be ethanol.

[0053] Therefore, the present invention provides a method for preparing a modified ZSM-5 molecular sieve. The molecular sieve prepared by the method does not use a template agent, has a simple synthesis method, and has high crystallinity. Using the molecular sieve for catalytic cracking / cracking reactions can increase the yield of light olefins in the target product.

[0054] The following is a detailed description of the embodiments of the present invention. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually based on conventional conditions. The following ratios are mass ratios unless otherwise specified.

[0055] Source of raw materials:

[0056] 1) ZSM-5 molecular sieve: industrial product, produced by Lanzhou Petrochemical Company, with a crystallinity of 84%, a silicon-aluminum ratio (i.e., the molar ratio of silicon dioxide to aluminum oxide) of 5, and a Na2O content of 14.3wt%;

[0057] 2) Silica sol, tetraethyl silicate, methyl orthosilicate or water glass, ethylamine, n-butylamine, ferric nitrate, ferric chloride, ferric sulfate, titanium nitrate, titanium sulfate, titanium chloride, silver nitrate, silver sulfate, cardanol, ethylene oxide, tert-butoxide base, anhydrous ethanol, 1,3-propane sultone, 1,4-butane sultone, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate: analytically pure, all chemical reagents;

[0058] Evaluation methods used in the examples

[0059] Evaluation of catalytic cracking reaction selectivity: The catalytic reaction selectivity was evaluated in a small fixed fluidized bed (FFB) test device (XGL-2, produced in Luoyang). The catalyst was pre-treated at 800°C and 100% steam for 10 hours. The reaction feed oil was Lanzhou Petrochemical light gasoline, the specific properties of which are shown in Table 1. The reaction temperature was 600-685°C, and the air velocity was 12-15h. -1 , the agent-oil ratio is 4-12.

[0060] Table 1 Raw oil properties

[0061] Percentage content / % Normal alkanes 6.97 Isoalkanes 44.18 Olefins 43.61 Cycloalkanes 4.27 Aromatics 0.97 MON 84.37 RON 92.9

[0062] Embodiment preparation method:

[0063] (1) mixing a silicon source, an alkali source and H2O to form a solution A; adding a metal salt solution to the above solution A, and then adding an additive, cardanol polyoxyethylene ether sulfonate, stirring at a constant speed at 50°C to 90°C for 15 to 60 minutes to form a mixed gel B;

[0064] (2) adding ZSM-5 seed crystals to the mixed gel B and stirring evenly for 1 to 3 hours to obtain a mixture C;

[0065] (3) The mixture C is crystallized, cooled to room temperature, centrifugally filtered, washed, dried and calcined to obtain a modified ZSM-5 molecular sieve, and the metal-modified ZSM-5 molecular sieve is ammonium exchanged to obtain a final modified ZSM-5 molecular sieve.

[0066] According to the above method, samples were prepared with reference to the selection of specific raw materials and implementation process conditions in Table 2 below.

[0067] Table 2 Selection and proportion of raw materials

[0068]

[0069]

[0070] Comparative Example 1 is the industrial product ZSM-5 molecular sieve of Lanzhou Petrochemical.

[0071] Comparative Example 2

[0072] Using CN 108238837 The modified ZSM-5 molecular sieve is prepared by method B, which is specifically as follows: ZSM-5 nano molecular sieve raw powder with a particle size distribution of 190-210nm and a silicon-aluminum ratio of 62 is placed in a crucible; a lanthanum nitrate solution with a concentration of 20-30wt% and a phosphoric acid solution with a concentration of 30-40wt%, and the above lanthanum nitrate solution and the phosphoric acid solution are mixed in a volume ratio of 1:1; the mixed solution of the above lanthanum nitrate and phosphoric acid is poured into the crucible, and a glass rod is used to stir while pouring the mixed solution to fully infiltrate the molecular sieve until the liquid level of the solution exceeds the original molecular sieve powder; then it is sent to a constant temperature water bath for infiltration at 60°C for 8 hours, and then the molecular sieve solution is filtered, and the filtered molecular sieve powder is sent to a muffle furnace for staged roasting, and the roasting temperature is kept constant at 120°C for 2 hours, 350°C for 4 hours, and 450 for 6 hours, that is, the modification of the molecular sieve is completed to obtain a modified ZSM-5 molecular sieve.

[0073] Comparative Example 3

[0074] The method is similar to that of Example 2, except that no cardanol polyoxyethylene ether sulfonate is added, and the modified molecular sieve is obtained under the same other conditions.

[0075] The crystallinity of the modified ZSM-5 molecular sieves obtained in each embodiment and comparative example is shown in Table 3.

[0076] The modified ZSM-5 molecular sieves obtained in Examples 1 to 5, Comparative Example 1 and Comparative Example 2 were evaluated on a fixed fluidized bed. The reaction conditions were as follows: reaction temperature 630°C, space velocity 15h -1 The agent-oil ratio is 8, the reaction pressure is 130 kPa (gauge pressure), and the evaluation results are shown in Table 4.

[0077] Table 3 Crystallinity of Examples and Comparative Examples

[0078]

[0079] As shown in Table 3, the crystallinity of the modified ZSM-5 molecular sieve synthesized in the embodiment of the present invention is higher than that of the ZSM-5 molecular sieve synthesized in Comparative Examples 1-3.

[0080] Table 4 Sample evaluation results

[0081]

[0082] As shown in Table 4, compared with the comparative example catalyst, the modified ZSM-5 molecular sieve prepared by the embodiment of the present invention is used for the catalytic cracking reaction of light gasoline, and the yield of light olefins in the target product is higher.

[0083] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a modified ZSM-5 molecular sieve, characterized in that: The steps include: Step 1, forming a gel with a silicon source, an alkali source, a metal salt solution and cardanol polyoxyethylene ether sulfonate; Step 2, adding ZSM-5 seed crystals to the gel, followed by crystallization, drying, and calcination to obtain a modified ZSM-5 molecular sieve; Wherein, the metal in the metal salt solution is at least one of iron, titanium and silver.

2. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: Step 1 The steps of forming a gel include: A silicon source, an alkali source and water are mixed to form a solution A, and the solution A is hydrolyzed for 15 to 40 minutes; a metal salt solution is added to the solution A, and then cardanol polyoxyethylene ether sulfonate is added, and the mixture is stirred to obtain the gel.

3. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: The silicon source is silica sol, tetraethyl silicate, methyl orthosilicate or water glass; the alkali source is ethylamine or n-butylamine; the cardanol polyoxyethylene ether sulfonate is cardanol polyoxyethylene ether sulfonate sodium, cardanol polyoxyethylene ether sulfonate magnesium or cardanol polyoxyethylene ether sulfonate ammonium.

4. The method for preparing a modified ZSM-5 metal salt solution according to claim 1, characterized in that: The metal salt in the metal salt solution is at least one of ferric nitrate, ferric chloride, ferric sulfate, titanium nitrate, titanium sulfate, titanium chloride, silver nitrate and silver sulfate.

5. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: The silicon source is in the form of SiO2, and the alkali source is in the form of OH - In terms of ions, the metal salt solution is calculated based on metal cations, the molar ratio of the silicon source, the alkali source, the metal salt solution and water is 1:2-10:0.01-0.05:4-10, and the molar ratio of the cardanol polyoxyethylene ether sulfonate to the silicon source is 0.005-0.03:

1.

6. The method for preparing the modified ZSM-5 molecular sieve according to claim 2, characterized in that: The stirring is performed at a temperature of 50° C. to 90° C., and the stirring time is 15 to 60 minutes.

7. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: The method also includes the step of exchanging the modified ZSM-5 molecular sieve with ammonium ions.

8. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: The mass ratio of the added amount of the ZSM-5 seed crystals to the gel is 1:100 to 5:100; the crystallization temperature is 130°C to 170°C, the time is 1h to 3h, and the crystallization method is microwave radiation heating; the drying temperature is 100 to 120°C, and the drying time is 8 to 12h.

9. The method for preparing the modified ZSM-5 molecular sieve according to claim 1, characterized in that: The synthesis steps of the cardanol polyoxyethylene ether sulfonate are: Step a, synthesizing cardanol polyoxyethylene ether by reacting cardanol with ethylene oxide under alkaline conditions; Step b, using cardanol polyoxyethylene ether as a raw material, adding tert-butanol base, using alcohol as a solvent, refluxing, then cooling the reaction system to room temperature, adding a sultone compound dropwise, refluxing, cooling, and obtaining cardanol polyoxyethylene ether sulfonate.

10. The method for preparing the modified ZSM-5 molecular sieve according to claim 9, characterized in that: The sultone compound is 1,3-propane sultone and / or 1,4-butane sultone.

11. The modified ZSM-5 molecular sieve prepared by the preparation method according to any one of claims 1 to 10.

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