Catalyst as well as preparation method and application thereof

Abstract

The invention provides a catalyst and a preparation method and application thereof.The preparation method of the catalyst comprises the following steps that after an initial molecular sieve is vacuumized, the initial molecular sieve and a hole plugging agent solution are mixed under the vacuum condition for hole plugging, and a catalyst precursor is obtained; and carrying out loading treatment on the catalyst precursor by adopting an active metal source solution to obtain the catalyst, the hole plugging agent solution comprises a hole plugging agent, and the hole plugging agent comprises fatty amine; the active metal source solution comprises an active metal precursor and a dispersing agent; the dispersing agent comprises at least one of polyacrylamide, polyvinylpyrrolidone and sodium dodecyl benzene sulfonate. According to the preparation method disclosed by the invention, the pore blocking agent is introduced into the molecular sieve through a vacuum adsorption technology, and high-dispersion loading of the active metal is performed on the basis, so that the loading amount of the active metal, especially noble metal, can be reduced on the basis of ensuring the overall activity of the catalyst, and thus the production cost of the catalyst is remarkably reduced.

Description

Technical Field

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

[0002] Molecular sieve materials, due to their unique pore structure, high specific surface area, and tunable acidity, play a crucial role as a support in numerous catalytic reactions. To impart specific catalytic activity, active metal components, such as noble metals like platinum, palladium, and rhodium, or transition metals like copper, nickel, and iron, are typically loaded onto their surfaces to form metal / molecular sieve composite catalysts. These catalysts are widely used in key areas such as petrochemical refining (e.g., hydroisomerization of n-alkane, hydrodesulfurization, and denitrification), fine chemical synthesis, environmental protection (e.g., catalytic combustion of volatile organic compounds, and automotive exhaust purification), and energy conversion. Their performance directly affects reaction efficiency, product selectivity, and process economy.

[0003] The activity and selectivity of a catalyst largely depend on the type, dispersion, and loading of the active metal supported on the molecular sieve surface. Generally, within a certain loading range, increasing the loading of the active metal helps provide more active sites, thereby significantly improving catalytic efficiency, such as accelerating the reaction rate and increasing the yield of the target product. However, active metals, especially highly active noble metals, are expensive raw materials. Pursuing high catalytic performance often means requiring the input of more noble metals, which directly leads to a sharp increase in catalyst manufacturing costs. This severely restricts the economic feasibility of such high-performance catalysts in large-scale industrial applications, creating an irreconcilable contradiction between improving catalytic performance and controlling costs.

[0004] Therefore, under the premise of ensuring or even improving the overall activity and selectivity of the catalyst, how to effectively reduce the loading of active metals, especially precious metals, or to seek better loading strategies to maximize the utilization efficiency of metal atoms, thereby significantly reducing the cost of the catalyst, has become a key problem that urgently needs to be solved in this technical field. Summary of the Invention

[0005] This application provides a catalyst, its preparation method, and its application. By introducing a plugging agent into the initial molecular sieve channels through vacuum adsorption technology, the channels can be effectively blocked without damage, thereby improving the utilization rate of active metals on the catalyst surface and reducing the catalyst production cost.

[0006] In a first aspect, this application provides a method for preparing a catalyst, comprising the following steps:

[0007] After vacuum treatment of the initial molecular sieve, the initial molecular sieve is mixed with a pore-blocking agent solution under vacuum conditions to perform pore-blocking treatment, thereby obtaining a catalyst precursor;

[0008] The catalyst precursor was loaded with an active metal source solution to obtain the catalyst.

[0009] The plugging agent solution includes a plugging agent, which includes fatty amines.

[0010] In one possible implementation, the volume ratio of the plugging agent to the pore volume of the initial molecular sieve is (0.8-1):(1-1.2).

[0011] In one possible implementation, the vacuuming process includes: placing the initial molecular sieve in a vacuum reactor, drawing a vacuum, and maintaining the vacuum for 15-30 minutes.

[0012] In one possible implementation, the plugging treatment includes: stirring a mixture comprising the initial molecular sieve and the plugging agent solution under vacuum conditions, followed by pressurizing to atmospheric pressure at 500-2000 Pa / min, wherein the stirring time is t, 15 min ≤ t ≤ 120 min.

[0013] In one possible implementation, the fatty amine has 2-8 carbon atoms.

[0014] In one possible implementation, the fatty amine includes at least one of diethylamine, dimethylisopropylamine, diisopropylamine, triethylamine, ethylamine, and diisopropylethylamine.

[0015] In one possible implementation, the mass ratio of the plugging agent to the solvent in the plugging agent solution is (1-5):(1-20); and / or, the solvent includes at least one of ethanol, methanol, isopropanol, acetone, and water.

[0016] In one possible implementation, the active metal source solution comprises an active metal precursor and a dispersant; the dispersant comprises at least one of polyacrylamide, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate, and the mass ratio of the active metal precursor to the dispersant is (0.1-20):(0.1-20).

[0017] Secondly, this application provides a catalyst, which is prepared by any one of the preparation methods described above.

[0018] Thirdly, this application provides a catalytic reaction, wherein the catalytic reaction is carried out using the above-mentioned catalyst.

[0019] This application provides a method for preparing a catalyst, in which a pore-blocking agent is introduced into the pores of a molecular sieve by vacuum adsorption, and then an active metal is loaded onto the outer surface of the molecular sieve. Thus, the preparation method of this application is simple to operate, highly controllable, and has good versatility. It can also stably prepare molecular sieve catalysts with highly dispersed active metals. While ensuring the overall activity of the catalyst, the loading of active metals, especially precious metals, can be reduced, thus significantly reducing the production cost of the catalyst. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a TEM image of the catalyst in Example 1 of this application;

[0022] Figure 2 This is a TEM image of the catalyst in Example 2 of this application;

[0023] Figure 3 This is a TEM image of the catalyst in Example 3 of this application;

[0024] Figure 4 This is a TEM image of the catalyst in Example 4 of this application. Detailed Implementation

[0025] 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.

[0026] To improve the utilization rate of active metals in catalysts and reduce catalytic costs, the inventors analyzed the catalyst structure. They discovered that the distribution of active metals in a catalyst is a key factor affecting its performance. The specific surface area of ​​a molecular sieve is mainly concentrated in its internal pore system, and reactant molecules must diffuse to reach the active sites within the pores. For systems with diffusion limitations, especially catalytic processes involving larger molecules or intrinsically high reaction rates, reactant molecules are more likely to be transformed at active sites on the catalyst's outer surface or at the pore openings, making it difficult to fully utilize the active centers deep within the pores. Therefore, active sites located on the outer surface have significantly higher utilization efficiency than those inside the pores due to their extremely high accessibility. Even if a large amount of active metal exists inside the pores, its effective catalytic contribution is significantly reduced due to mass transfer limitations, and the reaction rate is often controlled by the diffusion process.

[0027] Therefore, in order to prepare a catalyst that can fully utilize the active sites on the outer surface and is not limited by pore diffusion, it is possible to use a "pore-blocking agent" to pre-occupy the molecular sieve pores, prevent the active metal from entering the pores, and thus realize the utilization rate of the active metal on the outer surface of the catalyst.

[0028] However, in previous studies, despite achieving the sealing of the internal pores of molecular sieves, the overall catalytic efficiency of the catalysts remained unsatisfactory. This was mainly due to insufficient sealing effect and poor stability of the plugging agent, which led to precipitation of active metals during loading or damage to the molecular sieve framework structure.

[0029] Based on this, the first aspect of this application provides a method for preparing a catalyst, comprising the following steps:

[0030] After vacuum treatment of the initial molecular sieve, the initial molecular sieve is mixed with the pore-blocking agent solution under vacuum conditions to perform pore-blocking treatment, thereby obtaining the catalyst precursor;

[0031] The catalyst precursor was loaded with an active metal source solution to obtain the catalyst.

[0032] The plugging agent solution includes a plugging agent, which includes fatty amines.

[0033] In this application, the plugging agent solution includes aliphatic amine plugging agents and solvents. This application does not limit the solvent, as long as it can ensure that the plugging agent does not agglomerate in the plugging agent solution and can exist stably in the plugging agent solution.

[0034] The active metal source solution includes an active metal precursor and a solvent. In this application, the active metal precursor is the main component of the active metal source solution and serves as the source of the active metal loaded onto the surface of the catalyst precursor. The active metal in the active metal precursor can be at least one of Ni, Co, Mo, W, Pt, Pd, and Fe. Correspondingly, the active metal precursor can be a salt of the active metal, such as a sulfate, nitrate, or phosphate. The choice of solvent in the active metal source is not limited in this application, as long as it ensures the stable dispersion of the active metal source.

[0035] Furthermore, this application does not specifically limit the initial molecular sieve; it can be any molecular sieve in catalysts in the art, specifically including at least one of B, Al, Ga, and Fe. For example, it can be at least one of H-type mordenite zeolite molecular sieve, ZSM-5 molecular sieve, β-molecular sieve, and Y-type molecular sieve.

[0036] First, the initial molecular sieve is subjected to vacuum treatment to bring it into a vacuum state. Then, under vacuum conditions, the vacuum-treated initial molecular sieve and the plugging agent solution are mixed. At this time, the plugging agent solution enters the pores of the initial molecular sieve under negative pressure, thereby sealing the pores and obtaining the catalyst precursor.

[0037] Subsequently, the catalyst precursor was loaded with an active metal source solution. Since the pores in the gas before the catalyst were blocked by the plugging agent, the active metal source was mainly loaded on the surface of the catalyst precursor during the loading process and could not enter the pores of the molecular sieve.

[0038] This application controls the preferential distribution of active metals on the outer surface of molecular sieves, significantly reducing the amount of active metal used while ensuring that most active sites are located in regions where reactant molecules can quickly contact them. Although this method reduces the total number of active sites, it improves the effective utilization rate of metal per unit, thereby maintaining the overall activity of the catalyst. This reduces the catalyst manufacturing cost without negatively impacting its catalytic activity.

[0039] It is important to emphasize that this application utilizes a plugging agent solution to treat the initial molecular sieve under negative pressure, which significantly enhances its pore-sealing effect. This is because, compared to conventional atmospheric pressure immersion, negative pressure treatment is an active and forced process. The negative pressure environment effectively eliminates adsorbed gases (such as air and water vapor) and impurities within the molecular sieve pores, eliminating the barrier effect and spatial competition these substances create for the plugging agent solution's entry into the pores, and reducing the resistance to the solution wetting the pore walls. Under these conditions, the pressure difference between atmospheric pressure and the system becomes the primary driving force. This force actively propels the plugging agent solution to penetrate the tiny pores within the molecular sieve, overcoming mass transfer resistance caused by capillary forces and liquid viscosity, thereby achieving deeper and more thorough sealing.

[0040] Therefore, this process not only improves the effective depth and uniformity of the plugging agent in the pores, but also reduces the residue of surface solvent, laying the foundation for obtaining catalyst precursors with more precise metal distribution.

[0041] Furthermore, the aliphatic amine plugging agent selected in this application possesses both good physical and chemical stability, as well as suitable molecular rigidity. On the one hand, it maintains structural stability after entering the molecular sieve channels, and is not prone to decomposition or desorption, thereby achieving continuous and effective plugging of the channels. On the other hand, the plugging agent has sufficient rigidity to resist compression or deformation during subsequent active metal loading, avoiding a decrease in plugging effect due to competition for channel space with metal species, thus ensuring that the metal preferentially locates on the outer surface of the molecular sieve.

[0042] Therefore, the preparation method of this application, by selecting a suitable plugging agent and combining it with vacuum conditions for plugging treatment, not only significantly reduces the loading of active metals in the catalyst and saves raw material costs, but also effectively improves the utilization efficiency of active metals. This method ensures that active metals are preferentially loaded on the outer surface of the molecular sieve, avoiding ineffective deposition of metals inside the pores, thereby reducing preparation costs while ensuring the catalyst's high activity and high selectivity.

[0043] In the preparation process, to facilitate the subsequent loading process, the mixed solution containing the catalyst precursor can be filtered before loading. The filtered solid is then washed and dried to obtain the catalyst precursor. The washing agent can be at least one of ethanol, water, and acetone. Generally, washing can be performed 2-4 times, followed by drying at 80-120 °C. o Dry at C for 4-10 hours.

[0044] It should be noted that this application does not limit the specific method of loading treatment; it can be completed by an equal-volume impregnation method, wherein the impregnation temperature is 0~50℃, the impregnation time is 0.5~5h each time, and aging, drying, and calcination are performed after each impregnation to finally obtain the catalyst of this application. In the loading treatment, the mass content of metal elements in the active metal source solution can be controlled to be 0.1~20wt%.

[0045] This application does not limit the specific conditions for aging, drying, and calcination, and can be the same as conventional operations in the field. For example, the aging time is 4-12 hours; the drying temperature is 80-120°C, and the drying time is 4-10 hours; the calcination temperature is 500-600°C, preferably 550°C, and the calcination time is 2-6 hours.

[0046] As mentioned above, this application does not limit the selection of the initial molecular sieve. In one specific embodiment, the initial molecular sieve can be prepared by a one-step hydrothermal method.

[0047] First, a silicon source, an alkali source, a metal oxide, and deionized water are mixed to obtain a mixture. After stirring the mixture uniformly for 0-2 hours, zeolite seed crystals are added, and the mixture is stirred at 20-60℃ for 2-24 hours to obtain a precursor sol. The precursor sol is placed in a crystallization kettle for hydrothermal crystallization, then removed, filtered, washed, dried, subjected to ammonium exchange, and calcined to obtain the initial molecular sieve.

[0048] For example, the molar ratio of the silicon source, alkali source, metal oxide, and deionized water can be 0.01-30 : 0.01-12 : 0.01-3 : 0.01-1000, wherein the silicon source is calculated as SiO2, the alkali source as NaO2, and the metal oxide as M2O3. Further, the silicon source is selected from at least one of solid silica gel, silica sol, or tetraethyl orthosilicate; preferably, the silicon source is tetraethyl orthosilicate. The alkali source is selected from at least one of sodium hydroxide, potassium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide; preferably, the alkali source is sodium hydroxide. The metal oxide is selected from at least one oxide of B, Al, Ga, and Fe; preferably, the metal oxide is Al2O3.

[0049] In the preparation of the initial molecular sieve, this application does not limit the proportion and selection of zeolite seed crystals. Generally, based on the requirements of preparation cost and initial molecular sieve performance, the mass of zeolite seed crystals added is based on the mass of SiO2 (0.5%-4 wt%) in the silicon source. Specifically, the mass of the zeolite seed crystals is 0.5%-4 wt% of the mass of SiO2. The zeolite seed crystals can be, for example, at least one of SAPO-11 molecular sieve, ZSM-5 molecular sieve, MOR molecular sieve, β molecular sieve, and USY molecular sieve.

[0050] Furthermore, in order to ensure the degree of crystallization of the molecular sieve, the temperature of the above-mentioned hydrothermal crystallization is 100℃-180℃, and the time is 24-120h, preferably 12-36h.

[0051] To further obtain the molecular sieve catalyst prepared in this application, the loading treatment includes aging, drying, and calcination to obtain a molecular sieve catalyst with adjustable active metal loading positions; the aging time is 4-12 h, the drying time is 4-10 h, and the calcination time is 2-6 h.

[0052] In one specific embodiment, to ensure that the plugging agent can completely seal the initial molecular sieve channels, the volume ratio of the plugging agent to the pore volume of the initial molecular sieve can be controlled to be (0.8-1):(1-1.2), where the pore volume of the initial molecular sieve is the sum of the volumes of all channels within the initial molecular sieve. The inventors have found that when this volume ratio is met, the plugging agent is more effective at sealing the initial molecular sieve channels, thus preventing the active metal solution from entering the pores of the catalytic precursor, avoiding waste of the active metal, and thereby reducing the production cost of the catalyst.

[0053] In one specific embodiment, the initial molecular sieve is placed in a vacuum reactor and evacuated to a vacuum, which is maintained for 15-30 minutes. Specifically, maintaining the vacuum for a certain period is to completely remove adsorbed gases (N2, O2, H2O, etc.) and minute impurities from the molecular sieve channels, preventing impurities from occupying the internal space of the channels and affecting the sealing effect of the subsequent plugging agent on the initial molecular sieve.

[0054] It should be noted that this application does not limit the specific experimental apparatus for vacuum treatment; for example, it may be a low-vacuum reactor.

[0055] To further improve the sealing effect of the plugging agent on the pores of the initial molecular sieve, in one specific embodiment, the plugging treatment includes: stirring the mixture including the initial molecular sieve and the plugging agent solution under vacuum conditions, and then increasing the pressure to atmospheric pressure at 500-2000 Pa / min; wherein the stirring time is t, 15min≤t≤120min.

[0056] In detail, controlling the stirring time helps more plugging agent enter the pores under negative pressure, which not only improves the plugging effect but also prevents the plugging agent from occupying the surface of the initial molecular sieve and affecting the loading of the active metal. After the stirring process is completed, the pressure is increased to atmospheric pressure at the above-mentioned rate to ensure that the plugging agent molecules in the plugging solution fully diffuse and tightly adsorb within the initial molecular sieve pores, avoiding rapid pressure increase that could damage the pore structure (such as pore collapse or particle breakage) or cause uneven distribution of the plugging agent.

[0057] In one specific embodiment, to achieve more precise sealing of the initial molecular sieve pores by the plugging agent, an aliphatic amine with 2-8 carbon atoms can be selected. The inventors have discovered that aliphatic amines within this carbon number range exhibit better matching between their molecular size and the pore size distribution of the initial molecular sieve, as well as the target function of the final catalyst. On the one hand, this avoids excessive pore blockage due to excessively long carbon chains, which could affect the loading and dispersion of the active metal; on the other hand, it also prevents decreased sealing stability due to excessively short carbon chains, avoiding the problem of easy detachment during subsequent processing.

[0058] In one specific embodiment, in order to make the plugging agent more accurately match the initial molecular sieve pore characteristics, at least one of diethylamine, dimethylisopropylamine, diisopropylamine, triethylamine, ethylamine, and diisopropylethylamine can be selected as the plugging agent.

[0059] In one specific embodiment, the plugging solution comprises a plugging agent and a solvent, wherein the mass ratio of the plugging agent to the solvent is (1-5):(1-20). The inventors have discovered that when the above mass ratio is met, the plugging solution can maintain a suitable viscosity, making it easy to enter the pores of the initial molecular sieve, allowing the plugging agent to be uniformly adsorbed on the entire inner surface of the pores, thereby achieving effective and deep sealing of the catalyst pores.

[0060] When preparing a plugging solution, the plugging agent is dissolved in a solvent. The viscosity of the solution can be effectively controlled by the solvent's ability to fully dissolve, disperse, and transport the plugging agent. The solvents that can be selected include at least one of ethanol, methanol, isopropanol, acetone, and water.

[0061] In one specific embodiment, the active metal source solution includes an active metal precursor and a dispersant, wherein the dispersant includes at least one of polyacrylamide, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate, and the mass ratio of the active metal precursor to the dispersant is (0.1-20):(0.1-20).

[0062] The dispersant of this application can effectively inhibit the agglomeration of active metals through steric hindrance or electrostatic repulsion, thereby forming highly dispersed active metal particles on the surface of the molecular sieve. The inventors discovered that when this mass ratio is met, the dispersant can fully encapsulate the active metal ions, effectively inhibiting their migration and agglomeration during subsequent calcination, thus resulting in a more uniform distribution of active metals on the catalyst surface. This not only helps to improve the utilization rate of active metals and enhance catalytic activity, but also reduces catalyst production costs while lowering the active metal loading.

[0063] In one specific embodiment, an active metal salt is dissolved in a solvent to obtain a metal precursor, and then a dispersant is dissolved in the solvent and mixed with the metal precursor to obtain the active metal source solution of this application.

[0064] The second aspect of this application provides a catalyst prepared by any of the methods described above.

[0065] The catalyst of this application can reduce the amount of active metal by about 40% while maintaining high catalytic performance.

[0066] A third aspect of this application provides a catalytic reaction carried out using the catalyst described above.

[0067] Specifically, the catalyst of this application is used in the alkane hydroisomerization reaction, and the reaction process conditions are: reaction temperature 180-350°C. o C, the reaction pressure is 1-6 MPa, and the mass hourly space velocity of n-alkane is 0.5-6 h⁻¹. -1 The hydrogen flow rate is 50-200 ml / min.

[0068] Furthermore, the alkane is one of n-hexane, n-heptane, n-decane, n-dodecane, and n-octadecane.

[0069] The preparation method of this application will be described in detail below through specific embodiments.

[0070] The MOR molecular sieves used in Examples 1-5 and Comparative Examples 1-7 of this application were all purchased from Nanjing Chemical (Tianjin) Catalyst Co., Ltd.

[0071] Example 1

[0072] The catalyst preparation method in this embodiment includes the following steps:

[0073] 1) Place the MOR molecular sieve in a vacuum reactor, evacuate to a vacuum and maintain for 30 min, then mix the MOR molecular sieve with the plugging agent solution under vacuum conditions, stir for 60 min, increase the pressure to atmospheric pressure at 1000 Pa / min, filter, wash, and dry at 100℃ for 10 h to obtain the catalyst precursor;

[0074] The plugging agent solution includes diisopropylamine and ethanol; the volume ratio of diisopropylamine to the pore volume of the MOR molecular sieve is 0.8:1, and the mass ratio of diethylpropylamine to ethanol is 1:10.

[0075] 2) Dissolve 0.26g of chloroplatinic acid hexahydrate in 10ml of deionized water to obtain an active metal precursor, and then dissolve 1.04g of polyvinylpyrrolidone in 12ml of ethanol and mix it evenly with the active metal precursor to obtain an active metal source solution.

[0076] After impregnating the catalyst precursor with the above-mentioned active metal source solution in equal volume, aging for 6 hours, drying at 110°C for 10 hours, and calcining at 550°C in a muffle furnace for 6 hours, the catalyst of this embodiment was obtained.

[0077] Example 2

[0078] The catalyst preparation method in this embodiment is basically the same as that in Example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.4 wt%.

[0079] Example 3

[0080] The catalyst preparation method in this embodiment is basically the same as that in Example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.3 wt%.

[0081] Example 4

[0082] The catalyst preparation method in this embodiment is basically the same as that in Example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.2 wt%.

[0083] Example 5

[0084] The catalyst preparation method in this embodiment includes the following steps:

[0085] 1) Mix tetraethyl orthosilicate, NaOH, Al2O3, and deionized water evenly at 25°C. o Stirring at C for 1 hour yields a mixture system in which the molar ratio of tetraethyl orthosilicate, NaOH, Al2O3, and H2O is 40:8:1:800.

[0086] 2) Add MOR zeolite seed crystals to the above mixture system and stir at 60°C for 6 hours to obtain the precursor sol; wherein, the mass of MOR zeolite seed crystals added is calculated as 1% of the mass of SiO2 in the system;

[0087] 3) The above precursor sol was placed in a crystallization vessel and dynamically crystallized at 180°C for 72 h. The crystallization product was collected, washed 4 times with deionized water until the pH of the washing solution was 7, and dried at 110°C for 10 h to obtain Na-type mordenite molecular sieve.

[0088] The above-mentioned Na-type mordenite molecular sieve was subjected to ammonium exchange with a 1.0 mol / L ammonium chloride solution three times, followed by filtration with deionized water, washing four times, and then... o Dry at C for 10 hours in a muffle furnace at 500°C. o Calcination in C for 6 hours yields H-type mordenite molecular sieve;

[0089] 4) Place the H-type mordenite molecular sieve in a vacuum reactor, evacuate to a vacuum and maintain for 30 min, then mix the H-type mordenite molecular sieve with the plugging agent solution under vacuum conditions, stir for 60 min, increase the pressure to atmospheric pressure at 1000 Pa / min, filter, wash, and dry at 110℃ for 10 h to obtain the catalyst precursor.

[0090] The plugging agent solution includes diisopropylamine and ethanol; the volume ratio of diisopropylamine to the pore volume of H-type mordenite molecular sieve is 0.8:1, and the mass ratio of diisopropylamine to ethanol is 1:10.

[0091] 5) Dissolve 0.26g of chloroplatinic acid hexahydrate in 10ml of deionized water to obtain an active metal precursor, and then dissolve 1.04g of polyvinylpyrrolidone in 12ml of ethanol and mix it evenly with the active metal precursor to obtain an active metal source solution.

[0092] After impregnating the catalyst precursor with the above-mentioned active metal source solution in equal volume, aging for 6 hours, drying at 110°C for 10 hours, and calcining at 500°C in a muffle furnace for 6 hours, the catalyst of this embodiment was obtained.

[0093] Comparative Example 1

[0094] The preparation method of the catalyst in the comparative example is basically the same as that in Example 1, except that MOR molecular sieves without vacuum treatment are directly used for impregnation treatment in step 2).

[0095] Comparative Example 2

[0096] The preparation method of the catalyst in the comparative example is basically the same as that in comparative example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.4 wt%.

[0097] Comparative Example 3

[0098] The preparation method of the catalyst in the comparative example is basically the same as that in comparative example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.3 wt%.

[0099] Comparative Example 4

[0100] The preparation method of the catalyst in the comparative example is basically the same as that in comparative example 1, except that in step 2): the mass percentage of the active metal in the metal source solution is 0.2 wt%.

[0101] Comparative Example 5

[0102] The preparation method of the catalyst in the comparative example is basically the same as that in Example 1, except that the plugging agent in step 1) is n-butanol.

[0103] Comparative Example 6

[0104] The preparation method of the comparative catalyst is basically the same as that of Example 1, except that in step 1), MOR molecular sieves are mixed with a pore-blocking agent solution, stirred for 60 min, filtered, washed, and dried at 100 °C for 10 h to obtain the catalyst precursor. Step 2) is the same as in Example 1.

[0105] Comparative Example 7

[0106] The preparation method of the catalyst in the comparative example is basically the same as that in Example 5, except that H-type mordenite molecular sieves without vacuuming and adsorption plugging agent treatment are directly used for impregnation treatment in step 5).

[0107] Experimental Example 1

[0108] The morphology of the catalyst in the TEM examples was analyzed, and the results are as follows: Figures 1-4 .

[0109] Figure 1 This is a TEM image of the catalyst of Example 1 of this application. Figure 2 This is a TEM image of the catalyst in Example 2 of this application. Figure 3 This is a TEM image of the catalyst in Example 3 of this application. Figure 4 This is a TEM image of the catalyst from Example 4 of this application. Figure 1-4 It is understood that in the catalyst prepared by the method provided in this application, the active metal elements are only loaded on the surface of the molecular sieve, rather than inside its pores.

[0110] Experimental Example 2

[0111] The molecular sieves of the examples and comparative examples were used in the hydroisomerization reaction, specifically including the following steps:

[0112] 1) The catalyst was loaded into the isothermal zone of the reaction tube of the fixed-bed reactor at a loading amount of 5g. The catalyst used in the experiment needed to be tableted and sieved into 40-60 mesh particles. The reactor temperature was set to 350℃, and N2 was purged for 10min. Then H2 was introduced to make the pressure inside the reaction tube 2MPa, the hydrogen flow rate 80mL / min, and the temperature was raised to 400℃ for catalyst reduction for 4h.

[0113] 2) Octane is fed into a preheating furnace via a plunger pump, and then into a fixed-bed reactor for reaction, yielding the reaction products. The reaction temperature is 260℃, and the mass hourly space velocity (WHSV) is 1 h⁻¹. -1 The reaction pressure was 2 MPa (hydrogen pressure) and the hydrogen flow rate was 80 mL / min. The reaction products were analyzed by gas chromatography, and the conversion rate of the raw materials and the yield of the product (i-C8) were calculated according to the following formula. The specific results are shown in Table 1.

[0114] Raw material conversion rate = (number of moles of raw material - number of moles of product) / number of moles of raw material × 100%

[0115] C8 isomer selectivity = (Number of moles of isomer C8 component in product) / (Number of moles of starting material - Number of moles of product) × 100%

[0116] i-C8 yield = feed conversion rate × isomeric C8 selectivity

[0117] Table 1

[0118]

[0119] As shown in Table 1, the catalyst prepared in this application has a significant catalytic effect on the hydroisomerization reaction.

[0120] 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 catalyst, characterized in that, Includes the following steps: After vacuum treatment of the initial molecular sieve, the initial molecular sieve is mixed with a pore-blocking agent solution under vacuum conditions to perform pore-blocking treatment, thereby obtaining a catalyst precursor; The catalyst precursor was loaded with an active metal source solution to obtain the catalyst. The plugging agent solution includes a plugging agent, which includes fatty amines.

2. The method according to claim 1, characterized in that, The ratio of the volume of the plugging agent to the pore volume of the initial molecular sieve is (0.8-1):(1-1.2).

3. The method according to claim 1 or 2, characterized in that, The vacuuming process includes: The initial molecular sieve was placed in a vacuum reactor and evacuated to a vacuum, then kept there for 15-30 minutes.

4. The method according to any one of claims 1-3, characterized in that, The plugging treatment includes: stirring the mixture including the initial molecular sieve and the plugging agent solution under vacuum conditions, and then increasing the pressure to atmospheric pressure at 500-2000 Pa / min; The stirring time is t, where 15 min ≤ t ≤ 120 min.

5. The method according to any one of claims 1-4, characterized in that, The fatty amine has 2-8 carbon atoms.

6. The method according to claim 5, characterized in that, The fatty amine includes at least one of diethylamine, dimethylisopropylamine, diisopropylamine, triethylamine, ethylamine, and diisopropylethylamine.

7. The method according to any one of claims 1-6, characterized in that, In the plugging agent solution, the mass ratio of plugging agent to solvent is (1-5):(1-20), and the solvent includes at least one of ethanol, methanol, isopropanol, acetone, and water.

8. The method according to any one of claims 1-7, characterized in that, The active metal source solution includes an active metal precursor and a dispersant; The dispersant includes at least one of polyacrylamide, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate, and the mass ratio of the active metal precursor to the dispersant is (0.1-20):(0.1-20).

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

10. A catalytic reaction, characterized in that, The catalyst of claim 9 is used.

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