A molecular sieve catalyst, its preparation method and application

Abstract

This application provides a molecular sieve catalyst, its preparation method, and its application. The preparation method includes the following steps: crystallizing a raw material solution including a structure-directing agent and a raw material source to obtain a molecular sieve precursor, the molecular sieve precursor including the structure-directing agent; subjecting the molecular sieve precursor to a first calcination treatment to obtain a first calcined product; subjecting the first calcined product to a first shaping treatment in a first shaping solution including a first shaping agent to obtain a catalyst precursor; the first shaping agent includes at least one selected from organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids, and organic acid compounds; and subjecting the catalyst precursor to ammonium exchange treatment and ammonium calcination treatment sequentially to obtain the molecular sieve catalyst. The preparation method of this application can prepare molecular sieve catalysts with suitable acidity, thereby helping to overcome the bottlenecks in improving the yield of target products by molecular sieve catalysts.

Description

Technical Field

[0001] This application relates to the field of catalysis, and more particularly to a molecular sieve catalyst, its preparation method, and its application. Background Technology

[0002] Molecular sieves, as porous crystalline materials with regular channel structures, tunable acidity, and high specific surface area, play an irreplaceable catalytic role in petrochemicals, fine chemicals, gas separation, and environmental remediation. Their unique shape-selective catalytic ability and tunable acid centers enable their wide application in key reactions such as catalytic cracking, hydrocracking, isomerization, alkylation, and volatile organic compound (VOC) treatment. With the increasing demands of modern industry for efficient, highly selective, and environmentally friendly reaction processes, the development of high-performance molecular sieve catalysts has become an important direction for promoting technological progress in related industries.

[0003] However, despite the significant structural advantages of molecular sieves, existing molecular sieve catalysts still suffer from several shortcomings in practical industrial catalytic applications, failing to fully meet increasingly stringent process requirements. Specifically, the catalytic performance of molecular sieves is constrained by multiple factors, including their acidity, pore accessibility, and structural stability. First, the acid strength and acid content distribution of molecular sieves still need optimization. While strong acid centers exhibit high catalytic activity, they are also prone to initiating deep reactions or carbon deposition, leading to rapid catalyst deactivation; conversely, weak acidity makes it difficult to effectively activate reactant molecules. Furthermore, in harsh reaction environments such as high temperature, high pressure, and the presence of water vapor, the crystal framework structure of some molecular sieves lacks stability, making them prone to dealumination or collapse, resulting in a significant decline in activity and selectivity over time. These limitations in acidity and pore properties collectively restrict the application potential of molecular sieve catalysts in more efficient, long-term operating scenarios.

[0004] Therefore, how to solve the above-mentioned problems of existing molecular sieve catalysts in order to improve the catalytic performance of molecular sieve catalysts and improve the yield of target products has become a key bottleneck in improving the efficiency of chemical processes. Summary of the Invention

[0005] This application provides a method for preparing a molecular sieve catalyst, which can prepare a molecular sieve catalyst with suitable acidity, thereby helping to overcome the limitations of molecular sieve catalysts in catalytic activity and improve the yield of target products.

[0006] This application provides a molecular sieve catalyst with excellent catalytic activity and selectivity, which is of great significance for improving the efficiency and economy of related industrial catalytic processes.

[0007] This application provides a catalytic method that is carried out with the participation of the above-mentioned molecular sieve catalyst, thus the catalytic reaction has the characteristic of high yield of target product.

[0008] This application provides a method for preparing a molecular sieve catalyst, comprising the following steps:

[0009] A raw material solution including a structure directing agent and a raw material source is subjected to crystallization treatment to obtain a molecular sieve precursor, wherein the molecular sieve precursor includes the structure directing agent;

[0010] The molecular sieve precursor is subjected to a first calcination treatment to obtain a first calcination product; in the first calcination treatment, the temperature is 100-250℃ and the time is 1-10h.

[0011] The first calcined product is subjected to a first shaping treatment in a first shaping solution including a first shaping agent to obtain a catalyst precursor; the first shaping agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids and organic acid compounds;

[0012] The catalyst precursor was subjected to ammonium exchange treatment and ammonium calcination treatment in sequence to obtain the molecular sieve catalyst.

[0013] The method described above further includes, before the ammonium exchange treatment: subjecting the product of the first shaping treatment to a second calcination treatment to obtain a second calcined product; in the second calcination treatment, the temperature is 250-350℃ and the time is 1-10h.

[0014] The second calcined product is subjected to a second shaping treatment in a second shaping solution containing a second shaping agent to obtain the catalyst precursor;

[0015] The second sizing agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids, and organic acid compounds.

[0016] The method described above further includes, prior to the ammonium exchange treatment, a third calcination treatment on the product of the second shaping treatment to obtain the catalyst precursor; the third calcination treatment is performed at a temperature of 350-550°C for a time of 1-10 hours.

[0017] The method described above, wherein the heating rate of the first calcination treatment is 1-10 °C / min; and / or,

[0018] The heating rate for the second calcination treatment is 1-10 °C / min; and / or,

[0019] The heating rate of the third calcination treatment is 1-10℃ / min.

[0020] In the method described above, the first setting agent comprises, wherein the organosilane compound includes at least one of trimethylchlorosilane, dimethyldichlorosilane, and methyltrichlorosilane; the organosilazane compound includes at least one of hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and N-(trimethylsilyl); the organoamine compound includes at least one of ethylenediamine, triethylamine, n-butylamine, and hexamethylenediamine; the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium tetrafluoroborate; and the organic acid compound includes at least one of citric acid, oxalic acid, malonic acid, adipic acid, and ethylenediaminetetraacetic acid; and / or,

[0021] In the second setting agent, the organosilane compound includes at least one of trimethylchlorosilane, phenyltrimethoxysilane, and vinyltriethoxysilane; the organosilazane compound includes at least one of hexamethyldisilazane, N,N-bis(trimethylsilyl)acetamide, and hexamethylcyclotrisilazane; the organic amine compound includes at least one of N,N-dimethylcyclohexylamine and quinoline; the ionic liquid includes at least one of tetrabutylphosphine tetrafluoroborate and 1-allyl-3-methylimidazolium chloride; and the organic acid compound includes at least one of citric acid, sulfosalicylic acid, and benzoic acid; and / or,

[0022] The mass of the first sizing agent is 10%-100% of the mass of the structure-directing agent.

[0023] The mass of the second sizing agent is 10%-100% of the mass of the structure-directing agent.

[0024] In the method described above, the structure-directing agent comprises at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylamine, and diethylamine.

[0025] In the method described above, the temperature of the first shaping treatment is 15-80°C and the time is 1-10h; and / or, the temperature of the second shaping treatment is 15-80°C and the time is 1-10h.

[0026] The method described above, wherein the ammonium exchange treatment comprises: mixing the catalyst precursor with an ammonium salt solution, and exchanging the ammonium salt solution at 60-100°C for 1-6 hours; the concentration of the ammonium salt solution is 0.1-1 mol / L; and / or,

[0027] The ammonium salt in the ammonium salt solution includes at least one of ammonium nitrate and ammonium chloride; and / or,

[0028] The ammonium exchange treatment is performed 3-5 times; and / or,

[0029] The mass-to-volume ratio of the catalyst precursor to the ammonium salt solution is 10-30 ml / g; and / or,

[0030] The ammonium roasting treatment is carried out at a temperature of 500-600℃ for 1-10 hours.

[0031] This application also provides a molecular sieve catalyst, obtained according to any of the preparation methods described above.

[0032] This application also provides a catalytic method using the molecular sieve catalyst described above.

[0033] The method for preparing the molecular sieve catalyst provided in this application employs a process including crystallization, calcination, and shaping. The first shaping treatment provides a protective anchoring effect on the pore structure of the crystallized molecular sieve precursor, enabling controllable fixation and slow-release decomposition of the structure-directing agent. This effectively maintains the integrity of the molecular sieve framework and the regularity of its pores during the gradual removal of the structure-directing agent. Subsequent ammonium exchange and ammonium calcination are synergistically controlled to achieve a gradient and precise distribution of acid sites in the molecular sieve, optimizing the arrangement and intensity of its catalytically active sites. Ultimately, a molecular sieve catalyst that significantly improves the yield of the target product is obtained, balancing the structural stability and catalytic performance of the molecular sieve. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0035] Figure 1 The XRD patterns of the molecular sieve catalysts in Examples 5-9 of this application are shown.

[0036] Figure 2 The XRD patterns of the MOR molecular sieves in Example 1 and Comparative Example 1 of this application are shown.

[0037] Figure 3 The XRD pattern of ZSM-5 molecular sieve in Example 2 of this application;

[0038] Figure 4 The images show the pyridine infrared spectra of the molecular sieve catalysts in Examples 5-9 of this application. Detailed Implementation

[0039] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0040] To reconstruct the spatial distribution of acidic sites in molecular sieves and simultaneously regulate acid density, the inventors studied the regulation of acidic site distribution and found that the distribution of acidic sites directly determines catalytic performance, but its regulation has always been a core challenge in existing technologies. Current technologies struggle to actively design the key characteristics of acidic sites, specifically in three core dimensions: First, the ratio of Brønsted acid to Lewis acid cannot be adjusted as needed, and the synergistic effect of the two acid sites is difficult to match the catalytic requirements of different reactions; second, the distribution of strong and weak acid sites lacks controllability, often resulting in excessive concentration of strong acid sites or insufficient proportion of weak acid sites, affecting reaction selectivity; third, the ratio of acid sites inside and outside the pores is unbalanced, with insufficient active sites inside the pores for some reactions, while excess acid sites outside the pores easily trigger side reactions.

[0041] This uncontrollable distribution leads to uneven dispersion of active sites in the catalytic reaction. During the reaction, areas with densely packed active sites are prone to excessive adsorption of reactants, which can trigger local overreactions and generate useless byproducts. At the same time, excessively high local reaction intensities can also accelerate the deposition of carbon species on the surface of active sites, causing carbon deposition and deactivation, which significantly weakens the catalytic activity of the molecular sieve catalyst and severely limits its efficient application in industrial catalysis.

[0042] Based on this, the first aspect of this application provides a method for preparing a molecular sieve catalyst, comprising the following:

[0043] A raw material solution including a structure directing agent and a raw material source is subjected to crystallization treatment to obtain a molecular sieve precursor, wherein the molecular sieve precursor includes a structure directing agent.

[0044] The molecular sieve precursor is subjected to a first calcination treatment to obtain a first calcination product; the temperature of the first calcination treatment is 100-250℃ and the time is 1-10h.

[0045] The first calcined product is subjected to a first shaping treatment in a first shaping solution including a first shaping agent to obtain a catalyst precursor; the first shaping agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids and organic acid compounds;

[0046] The catalyst precursor was subjected to ammonium exchange treatment and ammonium calcination treatment in sequence to obtain the molecular sieve catalyst.

[0047] First, this application crystallizes a feed solution including a structure-directing agent and a feed source to obtain a molecular sieve precursor. The core function of the structure-directing agent is to directionally induce the ordered coordination, assembly, and nucleation of the feed source during the molecular sieve crystallization stage through its molecular structure and charge properties, precisely controlling the formation and growth of specific topological pore structures in the molecular sieve, thus obtaining a molecular sieve precursor including the structure-directing agent.

[0048] Subsequently, the molecular sieve precursor is subjected to a first calcination treatment. The inventors discovered that during calcination at 100-250℃ for 1-10 hours, some volatile structure-directing agent components are gently removed, while the molecular sieve precursor framework is further strengthened, laying the structural foundation for the subsequent first shaping treatment. In addition, the first calcination treatment can also prevent residual free moisture and impurities in the precursor from interfering with the first shaping treatment, ensuring the effective interaction between the shaping agent and the molecular sieve surface.

[0049] It should be noted that the first shaping treatment is a key step in improving the structural stability and acid site distribution of the molecular sieve in this application. The specially selected first shaping agent adheres tightly to the inner wall of the molecular sieve pores and the surface of the framework through both physical coating and chemical adsorption. This not only anchors and constrains the structure-directing agent that was not completely removed after calcination, preventing it from rapidly decomposing and causing violent gas impacts that could lead to pore collapse during subsequent deep processing, but also constructs a rigid support structure, firmly locking the pore topology of the molecular sieve and improving the framework's resistance to high temperatures and impacts.

[0050] Finally, this application replaces the cations in the molecular sieve framework with ammonium ions through ammonium exchange treatment, providing a precursor for acid site formation. Then, ammonium calcination is used to promote the decomposition and removal of ammonium ions, converting them into Brønsted acid sites and achieving a regular distribution of the acid site gradient. This further optimizes the intensity and density of active sites and ensures improved catalytic performance.

[0051] Therefore, this application innovatively introduces a first shaping treatment combined with a first calcination treatment. Utilizing the coating and anchoring effect of the first shaping agent on the pore structure of the crystallized molecular sieve precursor, it achieves controllable fixation and slow-release decomposition of the structure-directing agent. This ensures the stable maintenance of the complete morphology of the molecular sieve framework and the regular structure of the pores throughout the gradual removal of the structure-directing agent. Subsequently, through the synergistic regulation of ammonium exchange and secondary calcination, a gradient-based precise arrangement of acid sites in the molecular sieve can be achieved, optimizing the distribution and intensity characteristics of catalytic active sites. Ultimately, this not only significantly improves the yield of the target product but also simultaneously ensures the structural stability and catalytic performance of the molecular sieve, achieving synergistic optimization of structure and performance.

[0052] In one specific embodiment, this application does not limit the selection of the above-mentioned raw material source. For example, the raw material source may include an alkali source, an aluminum source, or a silicon source, wherein the selection of the alkali source, aluminum source, and silicon source can be the same as the conventional selection in the art.

[0053] For example, the aluminum source can be at least one of boehmite, aluminum isopropoxide, and sodium aluminate; the silicon source can be at least one of tetraethyl orthosilicate, fumed silica, silica sol, and sodium silicate; and the alkali source can be at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide. Furthermore, to balance cost and product quality, the alkali source is selected from sodium hydroxide, the aluminum source from sodium aluminate, and the silicon source from silica sol.

[0054] Specifically, in preparing the raw material solution, the structure-directing agent and the raw material source are simply dispersed uniformly in water according to the target ratio. To avoid the introduction of impurities, deionized water can be selected as the medium for dispersing the raw material source. The target ratio of the alkali source, aluminum source, and silicon source can be determined based on the chemical composition of the molecular sieve.

[0055] Furthermore, the raw material solution may also include molecular sieve seed crystals. In one specific embodiment, the molecular sieve seed crystals include at least one of SAPO-11 molecular sieve, ZSM-5 molecular sieve, MOR molecular sieve, β molecular sieve, Y molecular sieve, and USY molecular sieve. Further, the mass of the molecular sieve seed crystals, calculated relative to the mass of SiO2 in the silicon source, is 4-8 wt% of the mass of SiO2.

[0056] In one specific embodiment, the crystallization treatment of the raw material solution includes: mixing a solution comprising an alkali source, an aluminum source, a silicon source, and a structure-directing agent, then adding molecular sieve seed crystals and stirring to obtain a raw material solution, and dynamically crystallizing it at 120-200℃ for 12-120 hours to obtain a molecular sieve precursor. The inventors have discovered that controlling the crystallization temperature and time can promote the uniform growth of molecular sieve crystals and ensure the distribution of framework aluminum species and the stability of the pore structure.

[0057] To ensure the homogeneity of the raw material solution, including the structure-directing agent and the raw material source, the stirring temperature needs to be controlled between 10-60℃ and the time between 2-8 hours. By controlling the temperature and time range of the stirring treatment, the seed crystals can be uniformly dispersed, providing a homogeneous nucleation environment for subsequent crystallization. At the same time, the introduction of seed crystals can regulate the pore structure of the molecular sieve catalyst.

[0058] In one specific embodiment, the molar ratio of silicon source, alkali source, aluminum source, structure directing agent, and deionized water in the raw material solution is (0.1-10):(0.01-4):(0.01-20):(0.1-10):(1-100). The inventors have discovered that when the molar ratio of the raw material solution is within this range, a molecular sieve precursor with high purity and stable structure can be prepared by the above method. In the above molar ratio, the silicon source is calculated as SiO2, the alkali source as Na2O, and the aluminum source as Al2O3.

[0059] Furthermore, the first setting solution includes a solvent in addition to the first setting agent. This application does not limit the solvent; for example, it can be at least one of water, alkane solvents, and alcohol solvents. In one specific embodiment, the mass-to-volume ratio of the first setting agent to the solvent is 0.01-0.8 g / ml.

[0060] It should be noted that after the first roasting process, the product of the first roasting process needs to be cooled down before the first shaping process. Generally, the temperature of the product of the first roasting process should be reduced to room temperature (20-30℃).

[0061] To further improve the conversion rate of raw materials and the selectivity of target products, and to enhance the synergistic advantages of molecular sieve structural stability and catalytic performance, in one specific embodiment, before the ammonium exchange treatment, the method further includes: subjecting the product of the first shaping treatment to a second calcination treatment to obtain a second calcined product; in the second calcination treatment, the temperature is 250-350℃ and the time is 1-10h; subjecting the second calcined product to a second shaping treatment in a second shaping solution including a second shaping agent to obtain a catalyst precursor; the second shaping agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids, and organic acid compounds.

[0062] The aforementioned second roasting and second shaping treatments can further remove residual guiding agents, while the shaping agent undergoes secondary coating and anchoring, significantly improving the rigidity of the framework and the regularity of the pores. This further reduces damage to the framework structure during subsequent ammonium exchange, providing a more stable substrate for acid site formation. Simultaneously, by limiting the temperature and time of the second roasting treatment, gradient temperature control between the first and second roasting treatments is achieved, further precisely regulating the pore microenvironment and resulting in a more uniform and rationally gradient distribution of acid sites generated during subsequent ammonium exchange.

[0063] Furthermore, the second setting solution includes a solvent in addition to the first setting agent. This application does not limit the solvent; for example, it can be at least one of water, alkane solvents, or alcoholic alkanes. In one specific embodiment, the mass-to-volume ratio of the second setting agent to the solvent is 0.01-0.8 g / ml.

[0064] It should be noted that after the second roasting process, the product of the second roasting process needs to be cooled down before the second shaping process. Generally, the temperature of the product of the second roasting process should be reduced to room temperature (20-30℃).

[0065] In one specific embodiment, prior to the ammonium exchange treatment, the process further includes: subjecting the product of the second shaping treatment to a third calcination treatment to obtain a catalyst precursor; the third calcination treatment is carried out at a temperature of 350-550°C for a time of 1-10 hours.

[0066] The inventors discovered that performing a third calcination treatment at the aforementioned temperature and time can further remove the directing agent and further enhance the density and stability of the framework. Simultaneously, it can prevent framework damage during ammonium exchange and precisely regulate the pore microenvironment, resulting in more uniform and better-matched acid site formation, ultimately significantly improving the yield of the target product and enhancing the synergistic effect of structural stability and catalytic performance.

[0067] Limiting the heating rate can prevent sudden changes in the temperature gradient within the molecular sieve channels caused by rapid heating, and reduce the surge in pressure within the channels caused by the rapid decomposition of the structure-directing agent and the generation of a large amount of gas, thereby effectively avoiding structural damage such as channel collapse and skeleton fracture.

[0068] In one specific embodiment, the heating rate of the first calcination treatment is 1-10℃ / min.

[0069] In another specific embodiment, the heating rate of the second calcination treatment is 1-10℃ / min.

[0070] In addition, the heating rate of the third calcination treatment is 1-10℃ / min.

[0071] Thanks to the controlled heating rate of the three-stage calcination process, the structure-directing agent can be removed in a stepwise and stable manner, allowing for more precise regulation of the pore microenvironment and skeleton density. Simultaneously, it avoids damage to the sizing agent coating layer caused by thermal shock, ensuring the continuous and stable support effect.

[0072] To further enhance the effect of the first shaping treatment, the first shaping agent contains at least one of the following: organosilane compounds: trimethylchlorosilane, dimethyldichlorosilane, and methyltrichlorosilane; organosilazane compounds: at least one of hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and N-(trimethylsilyl); organic amine compounds: at least one of ethylenediamine, triethylamine, n-butylamine, and hexamethylenediamine; ionic liquids: at least one of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium tetrafluoroborate; and organic acid compounds: at least one of citric acid, oxalic acid, malonic acid, adipic acid, and ethylenediaminetetraacetic acid.

[0073] To further enhance the effect of the second shaping treatment, the second shaping agent contains at least one of the following: organosilane compounds: trimethylchlorosilane, phenyltrimethoxysilane, and vinyltriethoxysilane; organosilazane compounds: at least one of hexamethyldisilazane, N,N-bis(trimethylsilyl)acetamide, and hexamethylcyclotrisilazane; organic amine compounds: at least one of N,N-dimethylcyclohexylamine and quinoline; ionic liquids: at least one of tetrabutylphosphine tetrafluoroborate and 1-allyl-3-methylimidazolium chloride; and organic acid compounds: at least one of citric acid, sulfosalicylic acid, and benzoic acid.

[0074] In one specific embodiment, the mass of the first sizing agent is 10%-100% of the mass of the structure-directing agent. In another specific embodiment, the mass of the second sizing agent is 10%-100% of the mass of the structure-directing agent. In this case, the support effect on the molecular sieve framework can be further extended, and the permeability of the pores in the molecular sieve can be further improved.

[0075] Furthermore, the structure-directing agent of this application includes at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylamine, and diethylamine.

[0076] The inventors discovered that controlling the temperature and time of at least one of the first and second shaping treatments helps to further enhance the catalytic activity of the molecular sieve. Specifically, the temperature of the first shaping treatment is 15-80℃, and the time is 1-10h; the temperature of the second shaping treatment is 15-80℃, and the time is 1-10h.

[0077] In one specific embodiment, the ammonium exchange treatment includes: mixing a catalyst precursor with an ammonium salt solution, and exchanging the ammonium salt solution at 60-100°C for 1-6 hours, wherein the concentration of the ammonium salt solution is 0.1-1 mol / L. The inventors have discovered that within the aforementioned temperature, time, and ammonium salt concentration range, a balance can be struck between ion exchange efficiency and acid site selectivity.

[0078] In one specific embodiment, the ammonium salt in the ammonium salt solution includes at least one of ammonium nitrate and ammonium chloride.

[0079] The number of ammonium exchange treatments is 3-5 times. Controlling the number of ammonium exchange treatments within this range can ensure the quality of NH4. + Uniformly displace metal ions, such as Na, in the molecular sieve framework. + This not only improves the overall ion exchange efficiency but also avoids excessive local concentration of acid sites, achieving selective distribution of acid sites.

[0080] Furthermore, the mass-to-volume ratio of the catalyst precursor to the ammonium salt solution is 10-30 ml / g, that is, each gram of catalyst precursor is mixed with 10-30 ml of ammonium salt solution for ammonium exchange treatment. Even further, the mass-to-volume ratio of the catalyst precursor to the ammonium salt solution is 20 ml / g. The inventors have found that controlling the above mass-to-volume ratio ensures that the catalyst precursor is fully dispersed in the solution, avoiding the loss of NH4+ due to insufficient solution. + It cannot reach deep metal ions; at the same time, it avoids excessive NH4+ in the solution. + The concentration is diluted, reducing the displacement rate per unit time.

[0081] In one specific embodiment, the ammonium roasting treatment is carried out at a temperature of 100-600℃ for a duration of 1-10 hours.

[0082] In a second aspect, this application provides a molecular sieve catalyst prepared by any of the methods described above.

[0083] The molecular sieve catalyst prepared in this application maintains a molecular sieve crystallinity of >95%, which can avoid structural damage during post-processing; the acid distribution control precision is improved by more than 50%, and the proportion of strong acid sites is reduced by 30%~80%.

[0084] In a third aspect, this application provides a catalytic method using the molecular sieve catalyst described in the second aspect above.

[0085] In one specific embodiment, the molecular sieve catalyst of this application is used for the catalytic isomerization reaction of alkanes, and the reaction conditions are: reaction temperature of 200-300℃ and feed mass hourly space velocity of 0.5-4h. -1 The reaction pressure is 1-4 MPa, and the hydrogen flow rate is 20-150 mL / min.

[0086] Because this catalytic method uses the aforementioned molecular sieve catalyst, it features high feed conversion rate and strong selectivity for target products.

[0087] The preparation method of this application will be described in detail below through specific embodiments.

[0088] Example 1

[0089] The molecular sieve catalyst preparation method in this embodiment includes the following steps:

[0090] 1) Weigh a certain amount of NaOH, NaAlO2, silica sol, structure directing agent (tetraethylammonium hydroxide) and deionized water and mix them. Then add MOR molecular sieve seed crystals (the mass of the zeolite seed crystals is 4% of the mass of SiO2) and stir at 25℃ for 3h to obtain a raw material solution including structure directing agent and raw material source. Then place it in a crystallization kettle and dynamically crystallize at 150℃ for 12h. After washing the obtained solid until neutral, dry it at 120℃ for 9h to obtain molecular sieve precursor.

[0091] The molar ratio of silica sol, sodium hydroxide, NaAlO2, structure directing agent, and deionized water is 1:0.3:0.03:0.1:17, where the silicon source is calculated as SiO2, the alkali source as Na2O, and the aluminum source as Al2O3.

[0092] 2) The molecular sieve precursor was heated to 250°C at a rate of 1°C / min, and then held at 250°C for 2 hours for the first calcination treatment. After the first calcination treatment, the first calcined product was cooled to room temperature;

[0093] 3) The first calcined product was immersed in a citric acid aqueous solution and stirred at 60°C for 6 hours for the first shaping treatment. After filtration and washing with deionized water, it was dried in an oven at 100°C to obtain the product after the first shaping treatment. The mass of citric acid was 60% of the mass of the structure directing agent. The mass-volume ratio of citric acid to water in the citric acid aqueous solution was 0.15 g / ml.

[0094] 4) The product from the first shaping treatment is heated to 350°C at a programmed rate of 4°C / min and held at that temperature for 2 hours for the second calcination treatment. After the second calcination treatment, the product is cooled to room temperature.

[0095] 5) The second calcined product was impregnated in a hexane solution of trimethylchlorosilane and stirred at 25°C for 2 hours for the second shaping treatment. After filtration, the product was dried at 100°C to obtain the product after the second shaping treatment. Among them, trimethylchlorosilane accounted for 50% of the mass of the structure directing agent. In the hexane solution of trimethylchlorosilane, the mass-volume ratio of trimethylchlorosilane to hexane was 0.10 g / ml.

[0096] 6) The product of the second shaping treatment was heated to 550°C at a programmed rate of 4°C / min and kept at a constant temperature for 6 hours to carry out the third calcination treatment to obtain the catalyst precursor;

[0097] 7) The above catalyst precursor was mixed with ammonium chloride solution for ammonium exchange at 80°C for 2 hours, and the ammonium exchange treatment was repeated 3 times. The mixture was then dried at 120°C for 9 hours. The concentration of the ammonium chloride solution was 1 mol / L, and the mass-to-volume ratio of the catalyst precursor to the ammonium chloride solution was 20 ml / g each time.

[0098] 8) The dried ammonium exchange product from step 7) was calcined at 550°C for 4 hours to obtain the molecular sieve catalyst of this embodiment.

[0099] Example 2

[0100] The molecular sieve catalyst preparation method in this embodiment includes the following steps:

[0101] 1) Weigh a certain amount of NaOH, NaAlO2, silica sol, structure directing agent TPAOH (tetrapropylammonium hydroxide) and deionized water and mix them. Stir at 30℃ for 4h to obtain a raw material solution including structure directing agent and raw material source. Then place it in a crystallization kettle and dynamically crystallize at 150℃ for 48h. After washing the obtained solid until neutral, dry it at 120℃ for 9h to obtain molecular sieve precursor.

[0102] The molar ratio of silica sol, sodium hydroxide, NaAlO2, structure directing agent, and deionized water is 1:0.01:0.03:0.35:9, where the silicon source is calculated as SiO2, the alkali source as Na2O, and the aluminum source as Al2O3.

[0103] 2) The molecular sieve precursor was heated to 100°C at a rate of 5°C / min, and then held at 100°C for 10 hours for the first calcination treatment. After the first calcination treatment, the first calcined product was cooled to room temperature;

[0104] 3) The first calcined product was immersed in a solution of ethylenediamine and stirred at 60°C for 6 hours for the first shaping treatment. After filtration and washing, it was dried in an oven at 100°C to obtain the product after the first shaping treatment. The mass of ethylenediamine was 50% of the mass of the structure directing agent. The mass-volume ratio of ethylenediamine to solvent in the ethylenediamine solution was 0.15 g / ml.

[0105] 4) The product from the first shaping treatment is heated to 250°C at a programmed rate of 2°C / min and held at that temperature for 10 hours for the second calcination treatment. After the second calcination treatment, the product is cooled to room temperature.

[0106] 5) The second calcined product was impregnated in a hexane solution of hexamethylcyclotrisilazane and stirred at 25°C for 2 hours for the second shaping treatment. After filtration, the product was dried at 100°C to obtain the product after the second shaping treatment. Among them, hexamethylcyclotrisilazane accounted for 80% of the mass of the structure directing agent. In the hexane solution of hexamethylcyclotrisilazane, the mass-volume ratio of hexamethylcyclotrisilazane to hexane was 0.2 g / ml.

[0107] 6) The product of the second shaping treatment was heated to 350°C at a programmed rate of 2°C / min and calcined at a constant temperature for 10 hours to carry out the third calcination treatment, thereby obtaining the catalyst precursor;

[0108] 7) The above catalyst precursor was mixed with ammonium chloride solution for ammonium exchange at 60°C for 5 hours, and the ammonium exchange treatment was repeated 3 times. The mixture was then dried at 120°C for 9 hours. The concentration of the ammonium chloride solution was 1 mol / L, and the mass-to-volume ratio of the catalyst precursor to the ammonium chloride solution was 20 ml / g each time.

[0109] 8) The dried ammonium exchange product from step 7) was calcined at 550°C for 4 hours to obtain the molecular sieve catalyst of this embodiment.

[0110] Example 3

[0111] The molecular sieve catalyst preparation method in this embodiment includes the following steps:

[0112] 1) Weigh a certain amount of NaOH, NaAlO2, silica sol, structure directing agent TEAOH (tetraethylammonium hydroxide) and deionized water and mix them. Stir at 60℃ for 3h to obtain a raw material solution including structure directing agent and raw material source. Then place it in a crystallization kettle and dynamically crystallize at 140℃ for 72h. After washing the obtained solid until neutral, dry it at 120℃ for 9h to obtain molecular sieve precursor.

[0113] The molar ratio of silica sol, sodium hydroxide, NaAlO2, structure directing agent, and deionized water is 1:0.106:0.02:0.36:11.8, where the silicon source is calculated as SiO2, the alkali source as Na2O, and the aluminum source as Al2O3.

[0114] 2) The molecular sieve precursor was heated to 200°C at a rate of 10°C / min, and then held at 200°C for 8 hours for the first calcination treatment. After the first calcination treatment, the first calcined product was cooled to room temperature;

[0115] 3) The first calcined product was immersed in an ethanol solution of tetrabutylphosphine tetrafluoroborate, stirred at 40°C for 6 hours for the first shaping treatment, filtered, washed, and then dried in an oven at 100°C to obtain the product of the first shaping treatment; wherein, the mass of tetrabutylphosphine tetrafluoroborate is 50% of the mass of the structure directing agent; in the solution of tetrabutylphosphine tetrafluoroborate, the mass-volume ratio of tetrabutylphosphine tetrafluoroborate to solvent is 0.1 g / ml;

[0116] 4) The product from the first shaping treatment is heated to 200°C at a programmed rate of 2°C / min and held at that temperature for 8 hours for the second calcination treatment. After the second calcination treatment, the product is cooled to room temperature.

[0117] 5) The second calcined product was immersed in a hexane solution of vinyltriethoxysilane and stirred at 25°C for 2 hours for the second shaping treatment. After filtration, the product was dried at 100°C to obtain the product after the second shaping treatment. In this product, vinyltriethoxysilane accounted for 70% of the mass of the structure directing agent. In the hexane solution of vinyltriethoxysilane, the mass-to-volume ratio of vinyltriethoxysilane to hexane was 0.15 g / ml.

[0118] 6) The product of the second shaping treatment was heated to 350°C at a programmed rate of 2°C / min and calcined at a constant temperature for 10 hours to carry out the third calcination treatment, thereby obtaining the catalyst precursor;

[0119] 7) The above catalyst precursor was mixed with ammonium chloride solution for ammonium exchange at 80°C for 5 hours, and the ammonium exchange treatment was repeated 3 times. The mixture was then dried at 120°C for 9 hours. The concentration of the ammonium chloride solution was 1 mol / L, and the mass-to-volume ratio of the catalyst precursor to the ammonium chloride solution was 20 ml / g each time.

[0120] 8) The dried ammonium exchange product from step 7) was calcined at 550°C for 4 hours to obtain the molecular sieve catalyst of this embodiment.

[0121] Example 4

[0122] The preparation method of this embodiment is basically the same as that of Example 1, except that steps 4) to 6) are omitted. That is, the product of step 3) is directly processed by steps 7) and 8) to obtain the molecular sieve catalyst of this embodiment.

[0123] Example 5

[0124] The preparation method of this embodiment is basically the same as that of Example 1, except that step 6) is omitted. That is, the product of step 5) is directly processed by steps 7) and 8) to obtain the molecular sieve catalyst of this embodiment.

[0125] Example 6

[0126] The preparation method of this embodiment is basically the same as that of Example 1, except that the citric acid aqueous solution in step 3) is used to replace the trimethylchlorosilane n-hexane solution in step 5).

[0127] Example 7

[0128] The preparation method in this embodiment is basically the same as that in Example 1, except that the heating rate in steps 2), 4) and 6) is 12℃ / min.

[0129] Example 8

[0130] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 3), the mass of citric acid is 5% of the mass of the structure directing agent.

[0131] Example 9

[0132] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 3), the mass of citric acid is 120% of the mass of the structure directing agent.

[0133] Example 10

[0134] The preparation method of this embodiment is basically the same as that of embodiment 1. The difference is that in step 3), the temperature of the first shaping treatment is 50°C and the time is 8h; in step 5), the temperature of the second shaping treatment is 40°C and the time is 3h.

[0135] Example 11

[0136] The preparation method in this embodiment is basically the same as that in Example 1, except that in step 7), the concentration of the ammonium chloride solution is 0.8 mol / L.

[0137] Example 12

[0138] The preparation method in this embodiment is basically the same as that in Example 1, except that in step 7), the concentration of the ammonium chloride solution is 0.6 mol / L.

[0139] Example 13

[0140] The preparation method in this embodiment is basically the same as that in Example 1, except that in step 7), the concentration of the ammonium chloride solution is 0.4 mol / L.

[0141] Example 14

[0142] The preparation method in this embodiment is basically the same as that in Example 1, except that in step 7), the concentration of the ammonium chloride solution is 0.2 mol / L.

[0143] Comparative Example 1

[0144] The preparation method of the molecular sieve catalyst in this comparative example includes the following steps:

[0145] 1) Weigh a certain amount of NaOH, NaAlO2, silica sol, structure directing agent (tetraethylammonium hydroxide) and deionized water and mix them. Then add MOR molecular sieve seed crystals (the mass of the zeolite seed crystals is 4% of the mass of SiO2) and stir at 25℃ for 3h to obtain a raw material solution including structure directing agent and raw material source. Then place it in a crystallization kettle and dynamically crystallize at 150℃ for 12h. After washing the obtained solid until neutral, dry it at 120℃ for 9h to obtain molecular sieve precursor.

[0146] The molar ratio of silica sol, sodium hydroxide, NaAlO2, structure directing agent, and deionized water is 1:0.3:0.03:0.1:17, where the silicon source is calculated as SiO2, the alkali source as Na2O, and the aluminum source as Al2O3.

[0147] 2) The above molecular sieve precursor was subjected to structure-directing calcination at 550℃ for 4 hours to obtain the catalyst precursor. The heating rate for the structure-directing calcination of the molecular sieve precursor was 1℃ / min.

[0148] 3) The above catalyst precursor was mixed with ammonium chloride solution for ammonium exchange at 80°C for 2 hours, and the ammonium exchange treatment was repeated 3 times. The mixture was then dried at 120°C for 9 hours. The concentration of the ammonium chloride solution was 1 mol / L, and the mass-to-volume ratio of the catalyst precursor to the ammonium chloride solution was 20 ml / g each time.

[0149] 4) The dried ammonium exchange product from step 3) was calcined at 550°C for 4 hours to obtain the molecular sieve catalyst of this comparative example.

[0150] Comparative Example 2

[0151] The preparation method of the molecular sieve catalyst in this comparative example is basically the same as that in Comparative Example 1, except that step 2) is omitted. That is, the molecular sieve precursor in step 1) is directly treated in steps 3) and 4).

[0152] Experimental Example 1

[0153] 1. The molecular sieve catalysts in the examples and comparative examples were analyzed by XRD, and the results are as follows: Figures 1-3 .

[0154] Figure 1 The XRD patterns of the molecular sieve catalysts in Examples 5-9 of this application are shown below. Figure 2 The XRD patterns of the MOR molecular sieves in Example 1 and Comparative Example 1 of this application are shown. By comparing with the standard spectrum (commercial H / MOR), it can be seen that the XRD patterns exhibit MOR topological diffraction peaks at 2θ = 9.72°, 19.61°, and 22.32°, and the peaks are clear and free of impurities, indicating that the molecular sieve synthesized in this application is mordenite.

[0155] Figure 3 This is the XRD pattern of ZSM-5 molecular sieve in Example 2 of this application. Figure 3 The characteristic reflections of the MFI frame at 2θ = 7.9°, 8.8°, 23.1°, 23.4° and 23.9° are shown, indicating that all samples have high crystallinity, and that the molecular sieve synthesized in this application is ZSM-5 molecular sieve.

[0156] 2. The molecular sieve catalysts of the examples and comparative examples were tested using NH3-TPD and Py-IR, and the results are shown in Table 1. Figure 4 The images show the pyridine infrared spectra of the molecular sieve catalysts in Examples 5-9 of this application.

[0157] Table 1

[0158]

[0159] Based on the data in Table 1, the following conclusions can be drawn:

[0160] The total acid content, strong acid content, and Brønsted acid content of the molecular sieve catalyst showed significant and regular differences with variations in the preparation process parameters. Example 1, using the complete preparation process, exhibited the highest total acid content (963 μmol / g) and Brønsted acid content (342 μmol / g), establishing a performance benchmark.

[0161] Example 2 (β molecular sieve) had a total acid content of 581 μmol / g and a β acid content of 185 μmol / g; Example 3 (ZSM-5 molecular sieve) had a total acid content of 720 μmol / g and a β acid content of 280 μmol / g, demonstrating that this method is universally applicable to different molecular sieves.

[0162] Comparing Example 1 with Examples 4 and 5, it can be seen that the roasting and shaping steps have a certain impact on the acid content, which indicates that multi-step gradient roasting and shaping treatment helps to further construct high-density acid centers.

[0163] Comparative Examples 1 and 6 show that the acid site formation efficiency can be further controlled by adjusting the selection of the fixative.

[0164] Comparing Examples 1 and 7, it can be seen that controlling the heating rate can further optimize the skeleton structure and promote acid site formation.

[0165] Comparing Examples 1, 8, and 9, it can be seen that the amount of setting agent also has a certain influence on the control of acid amount. Therefore, the amount of setting agent can be adjusted accordingly based on the acid amount requirements in actual applications.

[0166] As shown in Examples 1 and 11-14, the decrease in acid content gradually narrows as the concentration of the ammonium exchange solution decreases, exhibiting typical characteristics of fine-tuning. This fully demonstrates that the ammonium exchange concentration is a reliable and controllable key parameter for regulating the acid density of molecular sieves, especially the density of Brønsted acid sites.

[0167] The acid content of Comparative Example 1 (traditional one-step roasting) and Comparative Example 2 (no roasting) (total acid 723 and 646 μmol / g, respectively, and Brønsted acid 216 and 186 μmol / g, respectively) strongly demonstrates the important role of multi-step gradient roasting and shaping treatment in constructing rich and stable acid centers in this invention.

[0168] In summary, the preparation method of the present invention can directionally adjust the acid content and acid type distribution of molecular sieve catalysts within a wide range by controlling the ammonium exchange concentration in combination with gradient calcination and shaping processes, thereby providing a reliable path for optimizing catalyst acidity for specific reactions.

[0169] 3. The molecular sieve catalysts of Example 1 and Comparative Examples 1 and 2 were tested using Py-IR and 2,4,6-trimethylpyridine infrared spectroscopy. The results are shown in Table 2.

[0170] Table 2

[0171]

[0172] Table 2 shows that the multi-step gradient calcination and shaping treatment of the present invention can significantly promote the formation and retention of Brønsted acid sites in the internal channels of molecular sieves, thereby optimizing the spatial distribution of acid sites. As shown in Example 1, its internal BAS content is as high as 81.3%, indicating that the active acid sites are mainly concentrated inside the channels. In contrast, in Comparative Example 1, which uses a conventional one-step calcination method, although the internal BAS content is still relatively high, the total amount of acid sites (216 μmol / g) is significantly reduced, indicating that this simple process is difficult to effectively construct abundant internal acid sites.

[0173] Secondly, the calcination process, especially the setting and gradient of the calcination temperature, is one of the key means to control the spatial distribution of Brønsted acid in molecular sieves. A comparison shows that without calcination, acid sites accumulate extensively on the outer surface, while appropriate gradient calcination can control the spatial distribution of acidic sites on both the inner and outer surfaces.

[0174] Experimental Example 2

[0175] In the experiment, catalyst, after being compressed into tablets and sieved to a particle size range of 40-60 mesh, was loaded into the isothermal zone of a reaction tube with an inner diameter of 13 mm, with a loading amount of 5 g. Octane was fed via a plunger pump, first flowing through a preheating furnace at 120°C for vaporization and preheating, and then entering the reactor for reaction. The reaction effluent was collected as liquid products via a three-stage condensation system. The composition of the reaction products was analyzed using an Agilent 7890B gas chromatograph.

[0176] The reaction conditions were set as follows: reaction temperature 260°C, mass hourly space velocity 1 h⁻¹. -1The reaction pressure was 2 MPa (under hydrogen conditions), and the hydrogen flow rate was 100 mL / min. -1 .

[0177]

[0178]

[0179] i-C8 yield = feed conversion rate × C8 isomer selectivity

[0180] n 进料 and n 出口 These represent the number of moles of n-octane at the reactor inlet and outlet, respectively; n i-C8 This indicates the total number of moles of the target C8 isoalkane.

[0181] Table 3

[0182]

[0183] As shown in Table 3, this study clarified the synergistic regulation mechanism of molecular sieve topology, calcination process, shaping treatment and ammonium exchange concentration on the catalytic performance of molecular sieves.

[0184] First, different molecular sieve types exhibit differentiated catalytic properties. Example 1 (MOR, complete process) showed the highest catalytic activity (conversion rate 57.6%) and a better overall yield (47.3%), indicating that the gradient calcination dual-sizing process can effectively construct a highly active catalytic system.

[0185] A comparison between Example 2 (β-zeolite) and Example 3 (ZSM-5) reveals the regulatory effect of zeolite topology on performance: β-zeolite, with its three-dimensional twelve-membered ring macropores facilitating diffusion, exhibits significantly improved selectivity (88.1%), but its conversion rate is relatively low (38.1%) due to its relatively weak acid strength. ZSM-5, relying on the shape selectivity of its ten-membered ring channels and suitable acidity, achieves a good balance between conversion rate (50.5%) and selectivity (81.0%), with a yield of 40.9%.

[0186] Secondly, the integrity of the calcination and shaping processes is crucial to catalytic activity. The conversion rates (49.3%, 56.4%) and yields (39.2%, 41.7%) of Example 4 (omitting the second and third calcinations and the second shaping) and Example 5 (omitting the third calcination) were both lower than those of Example 1, indicating that the second shaping, second calcination, and third calcination processes can further enhance acid site construction and structural stability, thereby improving catalytic activity.

[0187] Example 6 (using citric acid as the setting agent in both cases) maintained a high conversion rate (56.3%) while significantly improving selectivity to 86.2% and achieving the highest yield (48.5%). This indicates that proper matching of setting agents can optimize acid site distribution and significantly suppress side reactions.

[0188] Examples 8 and 9 demonstrate that further limiting the amount of setting agent can further improve the coating integrity and increase pore unobstructedness or selective acid sites, resulting in a more significant yield increase. Meanwhile, Example 7 shows that further limiting the heating rate can also further ensure the integrity of the setting layer or framework structure, thereby facilitating the formation of highly selective acid sites. Therefore, comparing Example 1 with Examples 7, 8, and 9 respectively shows that further controlling the heating rate and the amount of setting agent helps to further improve the yield.

[0189] Furthermore, the ammonium exchange concentration allows for precise control of catalytic performance. As shown in Examples 11-14, the conversion rate systematically decreases with decreasing ammonium exchange concentration, while the selectivity generally increases, with the yield fluctuating between 44.2% (Example 11) and 40.1% (Example 14). This indicates that by adjusting the ammonium exchange concentration, the acid density can be precisely controlled within a certain range, thereby achieving a controllable trade-off between catalytic activity and selectivity to meet the needs of different reaction scenarios.

[0190] While the conversion rates of Comparative Example 1 (conventional one-step calcination) and Comparative Example 2 (no calcination) (46.2% and 40.3%, respectively) were higher than some previous expectations, their yields (35.7% and 30.7%) were still significantly lower than most optimized examples. Both examples exhibited moderate selectivity, failing to compensate for insufficient activity through improved selectivity. This further highlights that conventional or simplified calcination processes struggle to achieve high selectivity while maintaining high activity, thus limiting yield improvements.

[0191] In summary, this application has successfully achieved targeted optimization of the activity and selectivity of molecular sieve catalysts through a multi-dimensional synergistic strategy involving molecular sieve structure selection, gradient calcination, multi-step shaping, and ammonium exchange concentration control.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application, and they should all be covered within the scope of the claims and specification of this application.

Claims

1. A method for preparing a molecular sieve catalyst, characterized in that, Includes the following steps: A raw material solution including a structure directing agent and a raw material source is subjected to crystallization treatment to obtain a molecular sieve precursor, wherein the molecular sieve precursor includes the structure directing agent; The molecular sieve precursor is subjected to a first calcination treatment to obtain a first calcination product; in the first calcination treatment, the temperature is 100-250℃ and the time is 1-10h. The first calcined product is subjected to a first shaping treatment in a first shaping solution including a first shaping agent to obtain a catalyst precursor; the first shaping agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids and organic acid compounds; The catalyst precursor was subjected to ammonium exchange treatment and ammonium calcination treatment in sequence to obtain the molecular sieve catalyst.

2. The method according to claim 1, characterized in that, Before the ammonium exchange treatment, the process further includes: subjecting the product of the first shaping treatment to a second roasting treatment to obtain a second roasted product; in the second roasting treatment, the temperature is 250-350℃ and the time is 1-10h. The second calcined product is subjected to a second shaping treatment in a second shaping solution containing a second shaping agent to obtain the catalyst precursor; The second sizing agent includes at least one of organosilane compounds, organosilazane compounds, organic amine compounds, ionic liquids, and organic acid compounds.

3. The method according to claim 2, characterized in that, Before the ammonium exchange treatment, the process further includes: subjecting the product of the second shaping treatment to a third calcination treatment to obtain the catalyst precursor; in the third calcination treatment, the temperature is 350-550℃ and the time is 1-10h.

4. The method according to claim 3, characterized in that, The heating rate of the first calcination treatment is 1-10℃ / min; and / or, The heating rate for the second calcination treatment is 1-10 °C / min; and / or, The heating rate of the third calcination treatment is 1-10℃ / min.

5. The method according to claim 2, characterized in that, In the first setting agent, the organosilane compound includes at least one of trimethylchlorosilane, dimethyldichlorosilane, and methyltrichlorosilane; the organosilazane compound includes at least one of hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and N-(trimethylsilyl); the organic amine compound includes at least one of ethylenediamine, triethylamine, n-butylamine, and hexamethylenediamine; the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium tetrafluoroborate; and the organic acid compound includes at least one of citric acid, oxalic acid, malonic acid, adipic acid, and ethylenediaminetetraacetic acid; and / or, In the second setting agent, the organosilane compound includes at least one of trimethylchlorosilane, phenyltrimethoxysilane, and vinyltriethoxysilane; the organosilazane compound includes at least one of hexamethyldisilazane, N,N-bis(trimethylsilyl)acetamide, and hexamethylcyclotrisilazane; the organic amine compound includes at least one of N,N-dimethylcyclohexylamine and quinoline; the ionic liquid includes at least one of tetrabutylphosphine tetrafluoroborate and 1-allyl-3-methylimidazolium chloride; and the organic acid compound includes at least one of citric acid, sulfosalicylic acid, and benzoic acid; and / or, The mass of the first sizing agent is 10%-100% of the mass of the structure-directing agent. The mass of the second sizing agent is 10%-100% of the mass of the structure-directing agent.

6. The method according to any one of claims 1-5, characterized in that, The structure-directing agent includes at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylamine, and diethylamine.

7. The method according to claim 2, characterized in that, The temperature of the first shaping treatment is 15-80℃ and the time is 1-10h; and / or the temperature of the second shaping treatment is 15-80℃ and the time is 1-10h.

8. The method according to any one of claims 1-7, characterized in that, The ammonium exchange treatment includes: mixing the catalyst precursor with an ammonium salt solution and exchanging the ammonium salt solution at 60-100°C for 1-6 hours; the concentration of the ammonium salt solution is 0.1-1 mol / L; and / or, The ammonium salt in the ammonium salt solution includes at least one of ammonium nitrate and ammonium chloride; and / or, The ammonium exchange treatment is performed 3-5 times; and / or, The mass-to-volume ratio of the catalyst precursor to the ammonium salt solution is 10-30 ml / g; and / or, The ammonium roasting treatment is carried out at a temperature of 500-600℃ for 1-10 hours.

9. A molecular sieve catalyst, characterized in that, It is obtained according to the preparation method according to any one of claims 1-8.

10. A catalytic method, characterized in that, The molecular sieve catalyst described in claim 9 is used.

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