A double-shell core-shell graded porous nickel-based catalyst, its preparation method and application

Abstract

This invention relates to a nickel-based catalyst, specifically a double-shell core-shell graded porous nickel-based catalyst, its preparation method, and its application. The catalyst comprises a core phase and a first shell and a second shell sequentially coating the core phase. The core phase is a molecular sieve, and the first shell is mesoporous silica, forming a stepped-pore structure. The second shell is nickel or nickel oxide, with a nickel content of 1-20 wt% of the total catalyst mass. Compared to existing technologies, this invention solves the problem that existing catalysts cannot simultaneously achieve a graded-pore structure and the synergistic effect of multiple active sites, realizing the construction of a stepped-pore structure and the effective tandem connection of active sites. Its preparation method is simple and low-cost, and it exhibits excellent catalytic performance in hydrodesulfurization reactions.

Description

Technical Field

[0001] This invention relates to a nickel-based catalyst, specifically to a double-shell core-shell graded porous nickel-based catalyst, its preparation method, and its application. Background Technology

[0002] With increasingly severe environmental problems, countries are placing higher and higher demands on environmental protection. Therefore, upgrading and cleaning fuel quality faces both significant opportunities and challenges, particularly in reducing the sulfur content of fuels. Sulfur compounds in fuels mainly include thiophene, benzothiophene, dibenzothiophene, and other polycyclic aromatic hydrocarbon derivatives. Among several desulfurization processes, hydrodesulfurization is the most commonly used industrial desulfurization technology. Developing high-performance hydrodesulfurization catalysts is a key issue that needs to be addressed. Nickel-based catalysts, with their advantages of low cost and moderate activity, are a major component of commonly used hydrodesulfurization catalysts.

[0003] Core-shell catalysts are an important new type of catalyst. Their defining characteristic is that a single material serves as the core phase, with a shell of the same or multiple materials grown on its outer surface. Utilizing this unique core-shell structure, it is hoped that multiple pore structures and active centers can be effectively integrated into a single particle while maintaining the original reactivity of each component, showing broad application prospects in catalysis and other fields. Although some core-shell catalysts have been disclosed in existing technologies, few have been mentioned regarding the synergistic effect of simultaneously achieving graded pore structures and multiple active centers (such as acid active centers and metal hydrogenation active centers) within a single catalyst.

[0004] Molecular sieves are commonly used catalysts that possess both acidic active centers and porous diffusion channels, and are frequently used in chemical processes such as catalytic cracking and isomerization. Fully utilizing the cracking and isomerization properties of molecular sieves holds promise for achieving synergistic effects in hydrocarbon reactions and hydrodesulfurization reactions, thereby improving catalytic efficiency. Previous patents have disclosed the application of molecular sieve catalysts in hydrodesulfurization reactions, such as Chinese patents CN201510764954.4, CN202010840132.0, and CN202011278321.X. In these catalysts, the molecular sieve is primarily used as a support, with the active metal loaded within the sieve pores. On the one hand, the metal loaded within the pores restricts diffusion within the molecular sieve channels to some extent; on the other hand, the acidic catalytic activity of the molecular sieve itself is rarely utilized.

[0005] Designing catalysts with molecular sieves as the core, preserving the properties of the molecular sieves as much as possible during synthesis, and appropriately separating the molecular sieves from the metal catalyst and constructing high-speed mass transfer channels between them are beneficial for further improving the hydrodesulfurization activity of the catalyst. Currently, the technologies reported in patents or literature are difficult to simultaneously achieve the synergistic effect of graded pore structure and multiple active centers (such as acid active centers, metal hydrogenation active centers, etc.). Therefore, this problem has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a double-shell core-shell graded porous nickel-based catalyst, its preparation method, and its application in order to solve at least one of the above-mentioned problems. This invention addresses the issue that existing catalysts cannot simultaneously achieve the synergistic effect of graded pore structure and multiple active centers, thus realizing the construction of a ladder-like pore structure and the effective tandem connection of active sites. The preparation method is simple and low-cost, and it exhibits excellent catalytic performance in hydrodesulfurization reactions.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The first aspect of the present invention discloses a double-shell core-shell graded porous nickel-based catalyst, which is composed of a core phase and a first shell and a second shell sequentially covering the outside of the core phase.

[0009] The core phase is a molecular sieve, and the first shell layer is mesoporous silica. The core phase and the first shell layer form a tiered pore structure.

[0010] The second shell is nickel or nickel oxide, and the nickel content is 1 to 20 wt% of the total mass of the catalyst.

[0011] Preferably, the core phase is one or more of Y-type molecular sieve, ZSM-5 molecular sieve and β molecular sieve, and the mass ratio of the core phase to the first shell is 0.5 to 10:1; the second shell is nickel or nickel oxide.

[0012] More preferably, the core phase is an ultrastable Y molecular sieve (USY).

[0013] A second aspect of this invention discloses a method for preparing the double-shell core-shell graded porous nickel-based catalyst as described above, comprising the following preparation steps:

[0014] S1: Mix molecular sieve, ethanol, water, concentrated ammonia and ethylenediamine in proportion and stir to obtain a suspension;

[0015] S2: Add 3-aminophenol, formaldehyde solution and tetraethyl orthosilicate sequentially to the suspension obtained in step S1 and stir. Filter, wash and dry to obtain a single-layer core-shell complex.

[0016] S3: The monolayer core-shell composite obtained in step S2 is mixed with an ethanol solution containing nickel salt and stirred, then heated to evaporate to dryness and dried to obtain a double-shell core-shell composite precursor;

[0017] S4: The double-shell core-shell composite precursor obtained by calcining step S3 yields a catalyst with nickel oxide as the second shell.

[0018] Alternatively, the preparation steps may include the following:

[0019] S1: Mix molecular sieve, ethanol, water, concentrated ammonia and ethylenediamine in proportion and stir to obtain a suspension;

[0020] S2: Add 3-aminophenol, formaldehyde solution and tetraethyl orthosilicate sequentially to the suspension obtained in step S1 and stir. Filter, wash and dry to obtain a single-layer core-shell complex.

[0021] S3: The monolayer core-shell composite obtained in step S2 is mixed with an ethanol solution containing nickel salt and stirred, then heated to evaporate to dryness and dried to obtain a double-shell core-shell composite precursor;

[0022] S4: The double-shell core-shell composite precursor obtained by calcining step S3 yields a catalyst with nickel oxide as the second shell.

[0023] S5: The catalyst with a second shell of nickel oxide obtained in the reduction step S4 is obtained as a catalyst with a second shell of nickel.

[0024] Preferably, in step S1, the feeding ratio of molecular sieve, ethanol and water is 0.5-5g:100mL:5-50mL, and the mass fraction of ammonia in the obtained suspension is 0.25-2.5wt%, and the mass fraction of ethylenediamine is 0.1-1wt%.

[0025] More preferably, the feeding ratio of molecular sieve, ethanol and water is (0.5-2g): 100mL: (20-30mL) (m / v / v), the mass fraction of ammonia is 0.5-1.5wt%, and the mass fraction of ethylenediamine is 0.3-0.5wt%.

[0026] Preferably, in step S2, the mass ratio of molecular sieve, 3-aminophenol and tetraethyl orthosilicate is 1:0.1-10:0.5-10, and the mass ratio of 3-aminophenol to formaldehyde is 0.1-10:1; the reaction temperature in step S2 is 10-70°C, and the reaction time is 0.5-50 hours.

[0027] More preferably, the mass ratio of molecular sieve, 3-aminophenol and tetraethyl orthosilicate is 1g:0.5-2g:0.5-5g, the mass ratio of 3-aminophenol to formaldehyde is 1.15:1 (m / m), the reaction temperature is 20-50℃, and the reaction time is 2-6 hours.

[0028] Preferably, in step S3, the nickel salt in the nickel-containing ethanol solution is one or more of nickel nitrate, nickel acetate, and nickel acetylacetonate, and the mass fraction of the nickel salt is 1-20 wt%; the solid-liquid mass ratio of the monolayer core-shell complex to the nickel-containing ethanol solution is 0.01-0.25:1, and the reaction temperature in step S3 is 50-100°C.

[0029] More preferably, the nickel salt is nickel nitrate with a mass fraction of 2-10 wt%; the solid-liquid mass ratio is 0.05-0.2:1; and the reaction temperature is 60-80℃.

[0030] Preferably, in step S4, the calcination heating rate is 1-20℃ / min, the temperature is 300-900℃, and the time is 2-12 hours.

[0031] More preferably, the heating rate is 5-10℃ / min, the temperature is 400-600℃, and the calcination time is 2-6 hours.

[0032] Preferably, in step S5, the reduction is carried out under a 5% hydrogen / argon atmosphere, with a heating rate of 1-20°C / min, a temperature of 300-900°C, and a calcination time of 2-12 hours.

[0033] More preferably, the heating rate is 5-10℃ / min, the temperature is 300-500℃, and the calcination time is 2-6 hours.

[0034] The third aspect of this invention discloses the application of a double-shell core-shell graded porous nickel-based catalyst as described above in hydrodesulfurization.

[0035] Preferably, the double-shell core-shell graded porous nickel-based catalyst is used for the hydrodesulfurization of dibenzothiophene at a temperature of 240–360°C and a pressure of 2–10 MPa.

[0036] The working principle of this invention is as follows:

[0037] The catalyst has a tiered pore structure and a distribution of multiple active centers. The tiered pore structure refers to the micropores, mesopores, and larger mesopores in the mesoporous silica shell of the molecular sieve. The distribution of multiple active centers refers to the acidic active centers of the molecular sieve and the metal hydrogenation active centers of the nickel-based catalyst, which are separately distributed in a single catalyst particle.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The dual-shell core-shell graded porous nickel-based catalyst provided by this invention integrates a molecular sieve, mesoporous silica, and a nickel-based catalyst into a single core-shell catalyst with uniformly encapsulated shells and clearly defined boundaries between the core and shell layers. This catalyst highly preserves the original pore structure of the molecular sieve and creates highly permeable mesoporous silica in the first shell layer. The original micropores and mesopores of the molecular sieve, combined with the larger mesopores in the mesoporous silica shell, form a tiered pore structure. Similarly, the acidic active centers of the molecular sieve are effectively preserved, and they are integrated with the metal hydrogenation active centers of the nickel-based catalyst within a single catalyst particle. These two components are separately distributed within the single catalyst particle, and the degree of separation can be precisely controlled.

[0040] The method for preparing a dual-shell core-shell graded porous nickel-based catalyst provided by this invention has advantages such as low cost, simple synthesis process, strong controllability, good reproducibility, and large-scale production capability. In the preparation process, firstly, a mixed shell layer composed of aminophenolic resin and silica is coated around the core phase through a synergistic deposition process of silica and aminophenolic resin in a sol-gel system; this is the precursor of the first shell layer. By adjusting the molecular sieve and the feed ratio of the two components in this step, the composition ratio and thickness of the composite layer can be effectively controlled, thereby precisely controlling the pore structure and shell thickness of the mesoporous silica shell layer after calcination to remove the aminophenolic resin. Then, a concentrated impregnation method is used to adsorb nickel-containing salts onto the catalyst particles to form a metal salt shell layer. This allows for easier adjustment of the nickel salt adsorption amount, thereby precisely controlling the nickel content in the prepared catalyst. It is particularly important to note that the aforementioned deposited mixed shell layer can effectively prevent Ni… 2+ Entering the molecular sieve interior ensures the separation between acid-active centers and metal hydrogenation-active centers. The aminophenolic resin component in the mixed shell, due to its ability to be removed by calcination, acts as a template agent; furthermore, it helps to immobilize Ni. 2+ This effectively improves the stability of the nickel salt shell.

[0041] The double-shell core-shell graded porous nickel-based catalyst prepared by the method described in this invention exhibits regular morphology, uniform size, and good dispersion. Furthermore, this invention achieves synergistic regulation of the obtained catalyst through multiple strategies, including the construction of a ladder-like pore structure and the integration of multiple active components, endowing the catalyst with excellent hydrodesulfurization catalytic activity. Specifically, its unique core-shell structure provides a ladder-like pore structure, abundant channels, and a large specific surface area, fully exposing active sites and providing favorable diffusion channels for mass transfer; the effective integration of both molecular sieve and nickel-based catalyst active components within a single core-shell catalyst is beneficial for fully leveraging the synergistic effect of the two components and improving catalytic efficiency. Attached Figure Description

[0042] Figure 1The image shows a transmission electron microscope (TEM) image of the catalyst (USY@mesoporous silica@nickel oxide) prepared in Example 1. The white dashed lines in the image indicate the shell boundaries.

[0043] Figure 2 The image shows a high-angle annular dark-field scanning transmission (HAADF-STEM) image and the corresponding elemental distribution map of the catalyst (USY@mesoporous silica@nickel oxide) prepared in Example 1.

[0044] Figure 3 Nitrogen adsorption-desorption isotherms for USY and the catalyst (USY@mesoporous silica@nickel oxide) prepared in Example 1;

[0045] Figure 4 X-ray powder diffraction (XRD) patterns of USY and the catalyst (USY@mesoporous silica@nickel oxide) prepared in Example 1;

[0046] Figure 5 The image shows a transmission electron microscope (TEM) image of the catalyst (nickel / (USY@mesoporous silica)) prepared in Comparative Example 1. The white dashed lines in the image indicate the shell boundaries. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] In the following embodiments, unless otherwise specified, commercially available products that are routinely available to those skilled in the art can be used, and the methods used can be conventional technical means used in the art.

[0049] A dual-shell core-shell graded porous nickel-based catalyst has a particle structure comprising a core phase, a first shell, and a second shell. The core phase is a molecular sieve, the first shell is mesoporous silica, and the second shell is nickel oxide or nickel. The catalyst exhibits a hierarchical pore structure and a multi-active-center distribution. The hierarchical pore structure refers to the micropores and mesopores of the molecular sieve, as well as the larger mesopores in the mesoporous silica shell. The multi-active-center distribution refers to the acidic active centers of the molecular sieve and the metal hydrogenation active centers of the nickel-based catalyst, which are separately distributed within a single catalyst particle. The mass ratio of the molecular sieve core to the mesoporous silica shell in the catalyst is 0.5–10, and the nickel content is 1–20 wt%.

[0050] A method for preparing the above-mentioned double-shell core-shell graded porous nickel-based catalyst specifically includes the following steps:

[0051] (1) Molecular sieve, ethanol, water, concentrated ammonia and ethylenediamine are mixed and stirred in a certain proportion to obtain a homogeneous suspension.

[0052] (2) 3-aminophenol, formaldehyde solution and tetraethyl orthosilicate were added to the suspension in sequence, stirred at a certain temperature for a period of time, and then filtered, washed and dried to obtain a single-layer core-shell composite with a mixed shell of aminophenol resin and silica coated on the molecular sieve.

[0053] (3) The powder obtained in the above steps is mixed with an ethanol solution containing nickel salt and stirred to obtain a uniform suspension. Then, it is heated in an oil bath until the liquid is basically evaporated and then dried to obtain a double-shell core-shell composite precursor coated with a mixed shell of aminophenol resin and silica and a nickel salt shell.

[0054] (4) The powder obtained in the above steps is placed in an atmosphere furnace, heated at a certain heating rate and kept at a certain temperature under an air atmosphere to obtain a nickel oxide catalyst with a double-shell core-shell graded pore structure.

[0055] (5) The powder obtained in the above steps is placed in an atmosphere furnace and heated and calcined at a certain heating rate under a 5% hydrogen / argon atmosphere to obtain a double-shell core-shell graded pore nickel-containing catalyst.

[0056] The nickel oxide-containing catalyst and the nickel metal-containing catalyst with double-shell core-shell graded pores mentioned in steps (4) and (5) are both nickel-based catalysts with double-shell core-shell graded pores as described in claim 1.

[0057] Furthermore, the molecular sieve may be one or more of Y-type molecular sieves, ZSM-5 molecular sieves, and β-molecular sieves. Preferably, the molecular sieve is an ultrastable Y molecular sieve (USY).

[0058] Further, the reaction conditions in step (1) are as follows: the feed ratio of molecular sieve, ethanol, and water is (0.5–5 g): 100 mL: (5–50 mL) (m / v / v). The mass fraction of ammonia is 0.25–2.5 wt%, and the mass fraction of ethylenediamine is 0.1–1 wt%. Preferably, the reaction conditions in step (1) are as follows: the feed ratio of molecular sieve, ethanol, and water is (0.5–2 g): 100 mL: (20–30 mL) (m / v / v). The mass fraction of ammonia is 0.5–1.5 wt%, and the mass fraction of ethylenediamine is 0.3–0.5 wt%.

[0059] Further, the reaction conditions in step (2) are as follows: the mass ratio of molecular sieve, 3-aminophenol, and tetraethyl orthosilicate is 1:0.1-10:0.5-10, the mass ratio of 3-aminophenol to formaldehyde is 0.1-10:1, the reaction temperature is 10-70℃, and the reaction time is 0.5-50 hours. Preferably, the reaction conditions in step (2) are as follows: the mass ratio of molecular sieve, 3-aminophenol, and tetraethyl orthosilicate is 1g:(0.5-2g):(0.5-5g), the mass ratio of 3-aminophenol to formaldehyde is 1.15:1 (m / m), the reaction temperature is 20-50℃, and the reaction time is 2-6 hours.

[0060] Further, the nickel-containing salt in step (3) is one or a mixture of nickel nitrate, nickel acetate, and nickel acetylacetonate. Preferably, the nickel-containing salt in step (3) is nickel nitrate.

[0061] Further, the reaction conditions in step (3) are: a reaction temperature of 50–100°C, a nickel salt-containing ethanol solution with a mass fraction of 1–20 wt%, and a solid-liquid mass ratio of 0.01–0.25:1. Preferably, the reaction conditions in step (3) are: a reaction temperature of 60–80°C, a nickel salt-containing ethanol solution with a mass fraction of 2–10 wt%, and a solid-liquid mass ratio of 0.05–0.2:1.

[0062] Further, the experimental conditions described in step (4) are: a heating rate of 1–20 °C / min, a temperature of 300–900 °C, and a calcination time of 2–12 hours. Preferably, the heating rate is 5–10 °C / min, the temperature is 400–600 °C, and the calcination time is 2–6 hours.

[0063] Further, the experimental conditions described in step (5) are: a heating rate of 1–20 °C / min, a temperature of 300–900 °C, and a calcination time of 2–12 hours. Preferably, the heating rate is 5–10 °C / min, the temperature is 300–500 °C, and the calcination time is 2–6 hours.

[0064] Application of the above-mentioned double-shell core-shell graded porous nickel-based catalyst in the hydrodesulfurization reaction of dibenzothiophene.

[0065] Furthermore, the reaction conditions for hydrodesulfurization are: temperature of 240–360°C and pressure of 2–10 MPa.

[0066] Example 1

[0067] This embodiment provides a method for preparing a double-shell core-shell graded porous nickel-based catalyst, which specifically includes the following steps:

[0068] (1) Mix USY, ethanol, water, concentrated ammonia (mass fraction of 25.0%) and ethylenediamine according to the feed amounts of 1.00g, 100mL, 25.0mL, 3.90mL and 0.56mL, and stir to obtain a homogeneous suspension;

[0069] (2) 3-aminophenol, formaldehyde solution (mass fraction of 37.0%), and tetraethyl orthosilicate (1.025 g, 2.25 mL, and 2.2 mL) were added sequentially to the suspension. The mixture was stirred at room temperature for 4 hours, then filtered, washed and dried to obtain a core-shell composite with a mixed shell of aminophenol resin and silica wrapped around the molecular sieve core phase.

[0070] (3) The powder obtained in the above steps is mixed with a nickel nitrate ethanol solution with a mass fraction of 4.5 wt%, and the solid-liquid ratio is 1:5.25 (m / m). Stir to obtain a homogeneous suspension, and then place it in a 70℃ oil bath and continue stirring until the liquid is basically evaporated, and then place it in a 70℃ oven to dry.

[0071] (4) The powder obtained in the above steps is placed in an atmosphere furnace, heated to 550°C at 5°C / min in an air atmosphere and kept at the temperature for 6 hours to obtain a double-shell core-shell graded porous molecular sieve@mesoporous silica@nickel oxide catalyst.

[0072] Figure 1 The transmission electron microscope (TEM) image of the double-shell core-shell graded porous nickel-based catalyst (USY@mesoporous silica@nickel oxide) prepared in this embodiment shows that the catalyst particles prepared above have three parts: a core phase, a first shell, and a second shell, and the boundaries between the layers (dashed lines in the figure) can be clearly distinguished.

[0073] Figure 2 High-angle annular dark-field scanning transmission (HAADF-STEM) images and elemental mapping diagrams were obtained for the prepared dual-shell core-shell graded porous nickel-based catalyst (USY@mesoporous silica@nickel oxide) in this embodiment. The elemental mapping diagrams show that Al is mainly distributed in the core phase, Si is mainly distributed in the core phase and the first shell, Ni is mainly distributed in the second shell, and O is uniformly distributed throughout the particle. This is consistent with the composition of each part, namely, the core phase is USY, the first shell is mesoporous silica, and the second shell is nickel oxide.

[0074] Figure 3 The nitrogen adsorption-desorption isotherms for the dual-shell core-shell graded porous nickel-based catalyst (USY@mesoporous silica@nickel oxide) prepared in this embodiment show that the dual-shell core-shell graded porous nickel-based catalyst prepared in this embodiment has a stepwise pore structure, and simultaneously possesses micropores (possessed by USY) and multi-level mesopore distribution (possessed by USY and the mesoporous silica shell).

[0075] Figure 4 The X-ray powder diffraction (XRD) patterns of the double-shell core-shell graded porous nickel-based catalyst (USY@mesoporous silica@nickel oxide) prepared for USY and this embodiment show that the catalyst prepared in this embodiment has diffraction peaks that match the standard cards (47-1049) of USY and NiO, respectively, indicating that the above-provided technical solution successfully prepared NiO while maintaining the FAU structure of USY.

[0076] Example 2

[0077] This embodiment provides a method for preparing a double-shell core-shell graded porous nickel-based catalyst, which specifically includes the following steps:

[0078] (1) Mix USY, ethanol, water, concentrated ammonia (mass fraction of 25.0%) and ethylenediamine according to the feed amounts of 1.00g, 100mL, 25.0mL, 3.90mL and 0.56mL, and stir to obtain a homogeneous suspension;

[0079] (2) 3-aminophenol, formaldehyde solution (mass fraction of 37.0%), and tetraethyl orthosilicate (1.025 g, 2.25 mL, and 2.2 mL) were added sequentially to the suspension. The mixture was stirred at room temperature for 4 hours, then filtered, washed and dried to obtain a core-shell composite with a mixed shell of aminophenol resin and silica wrapped around the molecular sieve core phase.

[0080] (3) The powder obtained in the above steps is mixed with a nickel nitrate ethanol solution with a mass fraction of 4.5 wt%, and the solid-liquid ratio is 1:5.25 (m / m). Stir to obtain a homogeneous suspension, and then place it in a 70℃ oil bath and continue stirring until the liquid is basically evaporated, and then place it in a 70℃ oven to dry.

[0081] (4) The powder obtained in the above steps is placed in an atmosphere furnace, heated to 550°C at 5°C / min in an air atmosphere and kept at the temperature for 6 hours to obtain a double-shell core-shell graded porous molecular sieve@mesoporous silica@nickel oxide catalyst.

[0082] (5) The powder obtained in the above steps is placed in an atmosphere furnace and heated to 450°C at 5°C / min under a 5% hydrogen / argon atmosphere and kept at the temperature for 4 hours to obtain a double-shell core-shell graded porous molecular sieve@mesoporous silica@nickel catalyst.

[0083] Example 3

[0084] The synthesis process is basically the same as in Example 1, except that the amount of USY added in step (1) is changed to 0.5g, and other conditions are the same as in Example 1.

[0085] Example 4

[0086] The synthesis process is basically the same as in Example 1, except that the amount of USY added in step (1) is changed to 2g, and other conditions are the same as in Example 1.

[0087] Example 5

[0088] The synthesis process is basically the same as in Example 1, except that the amount of tetraethyl orthosilicate added in step (2) is changed to 0.5 mL, and the other conditions are the same as in Example 1.

[0089] Example 6

[0090] The synthesis process is basically the same as in Example 1, except that the amount of tetraethyl orthosilicate added in step (2) is changed to 4 mL, and other conditions are the same as in Example 1.

[0091] Example 7

[0092] The synthesis process is basically the same as in Example 1, except that the mass fraction of the nickel nitrate ethanol solution in step (3) is changed to 1.0 wt%, and other conditions are the same as in Example 1.

[0093] Comparative Example 1

[0094] This comparative example provides a method for preparing a double-shell core-shell graded porous nickel-based catalyst, which is similar to the preparation method described in Example 2, except that the order of the synthesis steps in Example 2 has been changed. Specifically, it includes the following steps:

[0095] (1) Mix USY, ethanol, water, concentrated ammonia (mass fraction of 25.0%) and ethylenediamine according to the feed amounts of 1.00g, 100mL, 25.0mL, 3.90mL and 0.56mL, and stir to obtain a homogeneous suspension;

[0096] (2) 3-aminophenol, formaldehyde solution (mass fraction of 37.0%), and tetraethyl orthosilicate (1.025 g, 2.25 mL, and 2.2 mL) were added sequentially to the suspension. The mixture was stirred at room temperature for 4 hours, then filtered, washed and dried to obtain a core-shell composite with a mixed shell of aminophenol resin and silica wrapped around the molecular sieve core phase.

[0097] (3) The powder obtained in the above steps is placed in an atmosphere furnace, heated to 550°C at 5°C / min in an air atmosphere and kept at the temperature for 6 hours to obtain a material with a molecular sieve wrapped with a mesoporous silica shell.

[0098] (4) The powder obtained in the above steps is mixed with a nickel nitrate ethanol solution with a mass fraction of 4.5 wt%, and the solid-liquid ratio is 1:8.39 (m / m) to ensure that the Ni ratio in the final material is consistent with that in Examples 1 and 2. The mixture is stirred to obtain a homogeneous suspension, and then placed in a 70°C oil bath and stirred until the liquid is basically evaporated. Then it is placed in a 70°C oven to dry.

[0099] (5) The powder obtained in the above steps is placed in an atmosphere furnace and heated to 450°C at 5°C / min under a 5% hydrogen / argon atmosphere and kept at the temperature for 4 hours to obtain a double-shell core-shell graded porous molecular sieve@mesoporous silica@nickel catalyst.

[0100] From the appendix Figure 5 Observations show that, unlike the catalysts prepared in the above examples, the catalyst prepared in this comparative example only has a core phase and a first shell layer. The nickel component diffuses into the core phase (i.e., the molecular sieve) and the first shell layer, and does not have a nickel-based third shell layer. The metal active centers and acid active centers of the catalyst prepared in this comparative example are not clearly separated, and it does not have a graded structure of active centers.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing a molecular sieve catalyst with an outer mesoporous silica shell, comprising the core phase and the first shell layer of the catalyst prepared in Example 1:

[0103] (1) Mix USY, ethanol, water, concentrated ammonia (mass fraction of 28.0%) and ethylenediamine in amounts of 1.00 g, 100 mL, 25.0 mL, 3.90 mL and 0.56 mL respectively, and stir to obtain a homogeneous suspension.

[0104] (2) 3-aminophenol, formaldehyde solution (mass fraction of 37.0%), and tetraethyl orthosilicate (1.025 g, 2.25 mL, and 2.2 mL) were added sequentially to the suspension. The mixture was stirred at room temperature for 4 hours, then filtered, washed and dried to obtain a core-shell composite with a mixed shell of aminophenol resin and silica wrapped around the molecular sieve core phase.

[0105] (3) The powder obtained in the above steps is placed in an atmosphere furnace, heated to 550°C at 5°C / min in an air atmosphere and kept at the temperature for 6 hours to obtain a molecular sieve catalyst USY@mesoporous silica with an outer mesoporous silica shell.

[0106] Application Example 1

[0107] This application example uses a decahydronaphthalene solution of dibenzothiophene with a sulfur content of 300 ppm as the model oil to demonstrate the hydrodesulfurization performance of the catalysts described in Examples 1, 2, and 2 (Comparative Example 2). The hydrodesulfurization of dibenzothiophene was carried out in a 100 mL batch reactor at a reaction pressure of 6 MPa, a reaction temperature of 320 °C, a reaction time of 9 hours, a catalyst dosage of 200 mg, and a reaction liquid volume of 25 mL. The reaction evaluation results of the catalyst are shown in Table 1.

[0108] Table 1. Hydrodesulfurization performance of the catalysts in Examples 1, 2 and Comparative Example 2

[0109]

[0110]

[0111] The results of Application Example 1 and Table 1 show that the double-shell core-shell graded porous nickel-based catalyst prepared in this invention exhibits excellent catalytic performance in the hydrodesulfurization reaction of dibenzothiophene and has promising prospects for industrial application.

[0112] Application Example 2

[0113] This application example uses a decahydronaphthalene solution of dibenzothiophene with a sulfur content of 300 ppm as the model oil to demonstrate the hydrodesulfurization performance of the catalysts described in Examples 1 and 2 at different catalyst dosages. The hydrodesulfurization of dibenzothiophene was carried out in a 100 mL batch reactor at a reaction pressure of 6 MPa, a reaction temperature of 320 °C, a reaction time of 9 hours, and a reaction volume of 25 mL. The reaction evaluation results of the catalyst are shown in Table 2.

[0114] Table 2. Hydrodesulfurization performance of catalysts in Examples 1 and 2 at different catalyst dosages.

[0115] sample Catalyst mass (mg) Conversion rate (%) Desulfurization rate (%) USY@Mesoporous Silica@Nickel Oxide 200 91.9 83.5 USY@Mesoporous Silica@Nickel Oxide 100 81.2 59.6 USY@Mesoporous Silica@Nickel 200 94.4 88.1 USY@Mesoporous Silica@Nickel 100 79.3 50.0

[0116] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a double-shell core-shell graded porous nickel-based catalyst, characterized in that, The catalyst consists of a core phase and a first shell and a second shell that sequentially cover the outside of the core phase. The core phase is a molecular sieve, and the first shell layer is mesoporous silica. The core phase and the first shell layer form a tiered pore structure. The second shell layer is nickel or nickel oxide, and the nickel content is 1-20 wt% of the total mass of the catalyst. The preparation method includes the following steps: S1: Mix molecular sieve, ethanol, water, concentrated ammonia and ethylenediamine in proportion and stir to obtain a suspension; S2: Add 3-aminophenol, formaldehyde solution and tetraethyl orthosilicate sequentially to the suspension obtained in step S1 and stir. Filter, wash and dry to obtain a single-layer core-shell complex. S3: The monolayer core-shell composite obtained in step S2 is mixed with an ethanol solution containing nickel salt and stirred, then heated to evaporate to dryness and dried to obtain a double-shell core-shell composite precursor; S4: The double-shell core-shell composite precursor obtained by calcining step S3 yields a catalyst with nickel oxide as the second shell. Alternatively, the preparation steps may include the following: S1: Mix molecular sieve, ethanol, water, concentrated ammonia and ethylenediamine in proportion and stir to obtain a suspension; S2: Add 3-aminophenol, formaldehyde solution and tetraethyl orthosilicate sequentially to the suspension obtained in step S1 and stir. Filter, wash and dry to obtain a single-layer core-shell complex. S3: The monolayer core-shell composite obtained in step S2 is mixed with an ethanol solution containing nickel salt and stirred, then heated to evaporate to dryness and dried to obtain a double-shell core-shell composite precursor; S4: The double-shell core-shell composite precursor obtained by calcining step S3 yields a catalyst with nickel oxide as the second shell. S5: The catalyst with a nickel oxide second shell obtained in reduction step S4 is obtained as a catalyst with a nickel second shell. Specifically, through the synergistic deposition process of silica and aminophenolic resin in the sol-gel system, a mixed shell composed of aminophenolic resin and silica is formed around the core phase. This mixed shell effectively prevents Ni from entering the atmosphere. 2+ It enters the interior of the molecular sieve.

2. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, The core phase is one or more of Y-type molecular sieve, ZSM-5 molecular sieve and β molecular sieve, and the mass ratio of the core phase to the first shell is 0.5~10:1; the second shell is nickel or nickel oxide.

3. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, In step S1, the feeding ratio of molecular sieve, ethanol and water is 0.5~5 g:100 mL:5~50 mL, and the mass fraction of ammonia in the resulting suspension is 0.25~2.5 wt%, and the mass fraction of ethylenediamine is 0.1~1 wt%.

4. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, In step S2, the mass ratio of molecular sieve, 3-aminophenol and tetraethyl orthosilicate is 1:0.1~10:0.5~10, and the mass ratio of 3-aminophenol to formaldehyde is 0.1~10:

1. The reaction temperature in step S2 is 10~70℃, and the time is 0.5~50 hours.

5. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, In step S3, the nickel salt in the nickel-containing ethanol solution is one or more of nickel nitrate, nickel acetate, and nickel acetylacetone, and the mass fraction of the nickel salt is 1~20 wt%; the solid-liquid mass ratio of the monolayer core-shell complex to the nickel-containing ethanol solution is 0.01~0.25:1, and the reaction temperature in step S3 is 50~100℃.

6. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, In step S4, the calcination heating rate is 1~20℃ / min, the temperature is 300~900℃, and the time is 2~12 hours.

7. The method for preparing a double-shell core-shell graded porous nickel-based catalyst according to claim 1, characterized in that, In step S5, the reduction is carried out under a 5% hydrogen / argon atmosphere, with a heating rate of 1~20℃ / min, a temperature of 300~900℃, and a calcination time of 2~12 hours.

8. The application of a double-shell core-shell graded porous nickel-based catalyst prepared by any one of the preparation methods described in claims 1-7 in hydrodesulfurization.

9. The application according to claim 8, characterized in that, The aforementioned double-shell core-shell graded porous nickel-based catalyst is used for the hydrodesulfurization of dibenzothiophene at a temperature of 240~360℃ and a pressure of 2~10 MPa.

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