Preparation method and application of high-efficiency heavy oil hydrogenation monatomic molybdenum and nano molybdenum sulfide composite catalyst

Abstract

The application provides a preparation method of a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano molybdenum sulfide composite catalyst, which comprises the following steps: 1) mixing a crosslinking agent aqueous solution, a molybdenum salt and a chelating agent to obtain solution A; 2) mixing a polyvinyl alcohol solution with the solution A, and then adding a sulfuration agent and mixing to obtain solution B; 3) mixing a cationic surfactant aqueous solution with the solution B, and then drying and pyrolyzing to obtain the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano molybdenum sulfide composite catalyst; wherein the loading amount of molybdenum in the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano molybdenum sulfide composite catalyst is 3wt%-19wt%. The catalyst prepared by the method has excellent anti-coking performance and hydrogenation activity when used for heavy oil hydrogenation.

Description

Technical Field

[0001] This invention belongs to the field of oil lightening technology, specifically relating to the preparation of a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst and its application in heavy oil slurry bed hydrogenation. Background Technology

[0002] Petroleum, hailed as the "lifeblood of industry," is closely intertwined with socio-economic development. In recent years, with increasing fuel demand and the establishment of environmental regulations, the refining of heavy oil into lighter forms has become an effective way to alleviate the current energy shortage. Hydrogenation technology is a technique that can convert high-carbon, low-quality heavy oil into high-quality fuel oil and other products, effectively improving crude oil processing depth, light oil yield, and overall oil quality.

[0003] Heavy oil is the residue left after crude oil distillation to obtain light oil, and it is enriched with most of the sulfur, nitrogen, nickel, vanadium, and other metals from the crude oil. Heavy oil hydrogenation, through the action of a catalyst under high temperature and pressure conditions, reduces the content of heavy components, increases the yield of light oil, and thus enhances the economic value of heavy oil. Heavy oil is predominantly composed of heavy components, with high residual carbon values, large molecular sizes, and poor diffusion. Simultaneously, the generated coke easily deposits on the catalyst surface, leading to catalyst deactivation. Furthermore, coke easily deposits on the reactor walls, resulting in prolonged reaction cycles and reduced profitability. Therefore, to balance heavy oil hydrogenation and coking performance, the catalyst must not only have good hydrogenation activity but also possess good coking suppression capabilities to effectively prevent coke formation.

[0004] Traditional catalysts often result in significant waste due to low utilization rates of active metals. Single-atom catalysts, which disperse each atom onto the support surface, greatly improve the utilization rate of metal atoms and have therefore attracted widespread attention. However, since the active center consists of only one metal atom, its adsorption capacity for macromolecules is far less than that of large-particle active centers.

[0005] For example, Chinese patent document CN 112871150 A discloses a method for the controllable preparation and application of carbon-supported metal single-atom catalysts based on cyclodextrin supramolecular chemistry. Specifically, cyclodextrin supramolecular molecules are used as the carbon source. Utilizing the confinement and self-assembly of the cyclodextrin supramolecular molecules, a metal precursor is encapsulated within the cyclodextrin supramolecular cavity. Simultaneously, the cyclodextrin supramolecular molecules self-assemble with guest molecules containing heteroatoms, and the carbon-supported metal single-atom catalyst is prepared via high-temperature pyrolysis. However, this method only synthesizes single-atom catalysts, which exhibit poor coking suppression performance during heavy oil hydrocracking.

[0006] Chinese patent document CN 114917892 A discloses a method for preparing a carbon-based metal single-atom catalyst in a carbon dioxide cycloaddition reaction. The method includes: S1, mixing a carbon source, a nitrogen source, and a metal salt to obtain a mixture, wherein the carbon source serves as a support and the nitrogen source as a ligand; S2, ball milling the mixture to obtain a mixed intermediate; S3, heat-treating the mixed intermediate using a high-temperature pyrolysis method under an inert atmosphere, so that the metal single atoms in the metal salt are uniformly dispersed on the support through the ligand, thereby obtaining a carbon-based metal single-atom catalyst. However, this method synthesizes a single-atom catalyst, which exhibits poor coking suppression performance in heavy oil hydrocracking. Furthermore, the synthesized catalyst intermediate involves solid physical mixing and ball milling of the carbon source, nitrogen source, and metal salt before high-temperature calcination, which makes it difficult for the metal atoms to be fully homogenized with the carbon source, resulting in decreased catalyst activity.

[0007] Therefore, developing a catalyst that can improve the coking effect of heavy oil hydrotreating is of great significance for increasing the depth of crude oil processing, the yield of light oil, and improving the quality of oil products. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing a high-efficiency composite catalyst of single-atom molybdenum and nano-molybdenum sulfide for heavy oil hydrogenation. The catalyst prepared by this method has excellent anti-coking properties and hydrogenation activity when used for heavy oil hydrogenation.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing a high-efficiency composite catalyst for heavy oil hydrogenation consisting of single-atom molybdenum and nano-molybdenum sulfide includes the following steps:

[0011] 1) Mix the aqueous solution of the crosslinking agent, the molybdenum salt, and the chelating agent to obtain solution A;

[0012] 2) After mixing the polyvinyl alcohol solution with solution A, add the vulcanizing agent and mix well to obtain solution B;

[0013] 3) After mixing the aqueous solution of the cationic surfactant with the solution B, the mixture is dried and pyrolyzed to obtain a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst.

[0014] The molybdenum loading in the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst is 3wt%-19wt%.

[0015] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the mass ratio of polyvinyl alcohol in the polyvinyl alcohol solution to the crosslinking agent in the aqueous solution of the crosslinking agent is 1-10.

[0016] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the mass ratio of the cationic surfactant to the polyvinyl alcohol in the polyvinyl alcohol solution is 1-3.

[0017] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the concentration of the polyvinyl alcohol solution is 1wt%-5wt%.

[0018] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, conventional methods in the industry can be used for mixing in each step. The stirring method recommended by the present invention is used for mixing. The specific stirring rate and mixing time of each step are not specifically limited. The stirring rate does not affect the performance of the final product. The mixing time can be adjusted according to the actual situation, as long as the materials in each step are mixed evenly. In step 1) recommended by the present invention, the stirring and mixing time of the aqueous solution of the crosslinking agent, the molybdenum salt and the chelating agent is 1-3 hours; in step 2) recommended by the present invention, the stirring and mixing time of the polyvinyl alcohol solution and solution A is 0.5-3 hours, and the stirring and mixing time after adding the sulfiding agent is 1-3 hours; in step 3) recommended by the present invention, the stirring and mixing time of the aqueous solution of the cationic surfactant and solution B is 1-3 hours.

[0019] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the amount relationship between the chelating agent and the molybdenum salt is not specifically limited, and conventional methods in the industry can be used, such as the molar ratio of the chelating agent to the molybdenum salt calculated as molybdenum element being 1-10.

[0020] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the sulfiding agent is calculated based on sulfur element, the molybdenum salt is calculated based on molybdenum element, and the molar ratio of the sulfiding agent to the molybdenum salt is 1-5.

[0021] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the drying method and conditions in step 3) are not specifically limited; conventional drying methods in the industry can be used to remove moisture from the system. The drying temperature in step 3) recommended by the present invention is 50-80℃, and the time is 12-36h.

[0022] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, in step 3), the pyrolysis temperature is 450-750℃, the time is 2-4h, the heating rate is 1-5℃ / min, and the pyrolysis environment is a nitrogen atmosphere.

[0023] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the degree of alcoholysis of the polyvinyl alcohol is 70%-99% and the viscosity is 3-51 mPa.s.

[0024] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the crosslinking agent is selected from carbonyl-containing compounds, preferably at least one of tannic acid, glutaraldehyde, formaldehyde and succinic acid; more preferably tannic acid;

[0025] The cationic surfactant is selected from at least one of hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, dodecyl dimethyl benzyl ammonium chloride, and dodecyl dimethyl tertiary amine; preferably hexadecyltrimethylammonium chloride.

[0026] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the molybdenum salt, the chelating agent, and the sulfiding agent are not specifically limited, and conventional ones in the industry can be used. For example, the molybdenum salt can be selected from at least one of ammonium molybdate, ammonium molybdate tetrahydrate, sodium molybdate, and molybdenum chloride.

[0027] The chelating agent may be selected from at least one of glycine, disodium ethylenediaminetetraacetate, and hydroxylamine hydrochloride.

[0028] The vulcanizing agent may be selected from at least one of trithiocyanate, ammonium sulfide, sodium sulfide, and elemental sulfur.

[0029] Optionally, in the preparation method of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by the present invention, the concentration of the aqueous solution of the cationic surfactant is not specifically limited, as long as it can dissolve the cationic surfactant.

[0030] This invention also provides the application of the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst prepared by the above-mentioned method in heavy oil slurry bed hydrogenation.

[0031] Specifically, the present invention also provides a method for hydrogenating heavy oil, comprising the following steps:

[0032] After the catalyst is mixed evenly with FCC catalytic cracking diesel, it is added to low-quality heavy oil for hydrogenation reaction;

[0033] The catalyst is a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst prepared by the above-mentioned method.

[0034] Preferably, the catalyst, calculated by metal element, has a mass ratio of 50-1000 μg / g to the inferior heavy oil.

[0035] Optionally, in the heavy oil hydrogenation method provided by the present invention, a slurry bed is used, and the hydrogenation conditions can be those commonly used in the industry, such as an initial hydrogen pressure of 6-12 MPa, a reaction temperature of 420-440℃, and a reaction time of 1-2 h.

[0036] The beneficial effects of this invention are as follows:

[0037] 1. The present invention provides a method for preparing a high-efficiency composite catalyst for heavy oil hydrogenation using single-atom molybdenum and nano-molybdenum sulfide. This method addresses the problem of weak adsorption capacity of individual single-atom catalysts for heavy oil macromolecules by constructing a synergistic active center composed of single-atom sites and nanoparticle sites. The catalyst prepared by this method exhibits excellent heavy oil slurry-bed hydrogenation performance, demonstrates superior hydrogenation and coking suppression properties in hydrogenation reactions, and is low in cost and simple to synthesize, showing promising prospects for industrialization.

[0038] 2. The method for preparing a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum disulfide composite catalyst provided by this invention utilizes the abundant carbonyl sites in a water-soluble crosslinking agent to fix the chelate of molybdenum metal atoms. Simultaneously, it utilizes the crosslinking effect between the crosslinking agent and polyvinyl alcohol to form a stable network framework. Furthermore, it utilizes the site adsorption function of polyvinyl alcohol to adsorb the chelate of molybdenum metal atoms formed by the molybdenum salt and the chelating agent within the framework. A cationic surfactant is added as a framework filler. After high-temperature pyrolysis, the molybdenum metal atoms can form stable active sites with adjacent non-metal atoms. The method further limits the proportion of metal atoms in the prepared catalyst to a relatively high level, allowing unanchored molybdenum atoms to react with the sulfiding agent during drying to form molybdenum disulfide nanoparticles. The addition of the cationic surfactant acts as a framework filler, supporting the polyvinyl alcohol framework; it also serves as a coordinating agent and reacts with the intermediate product [MoS4]. 2- Coordination is performed to regulate the size and morphology of nanoparticles, preventing them from forming clusters. The other end of the cationic surfactant is a lipophilic group, which allows the entire composite catalyst to be better miscible with oil, thus giving it better stability, dispersibility, and lipophilicity. Therefore, the preparation method provided by this invention can form stable nanoparticles while forming single-atom sites, constructing a synergistic active center of single-atom sites and nanoparticle sites. Among them, molybdenum sulfide nanoparticles can improve the adsorption capacity of heavy oil macromolecules, improve coking performance, and effectively promote the consumption of activated hydrogen at molybdenum single-atom sites. Attached Figure Description

[0039] Figure 1 This is a transmission electron microscope image of the catalyst prepared in Example 1 of the present invention;

[0040] Figure 2 This is a transmission electron microscope (TEM) image of the catalyst prepared in Comparative Example 1 of the present invention.

[0041] Figure 3 This is a transmission electron microscope (TEM) image of the catalyst prepared in Comparative Example 2 of the present invention.

[0042] Figure 4 The above are EXAFS diagrams of the catalysts prepared in Example 1 and Comparative Example 1 of this invention.

[0043] Figure 5 This is a spherical aberration electron microscope image of the catalyst prepared in Example 1 of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0045] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0046] The present invention is further illustrated below by way of examples, but it is not intended to be limited thereto.

[0047] Example 1

[0048] Weigh 200 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 200 mg of ammonium molybdate and 200 mg of hydroxylamine hydrochloride. Stir for 1 hour to obtain solution A.

[0049] Weigh 0.5g of polyvinyl alcohol and dissolve it in 9.5g of deionized water to obtain a polyvinyl alcohol solution. Then, add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 0.5h. Then, add 150mg of trithiocyanate and stir for 1h to obtain solution B.

[0050] 600 mg of hexadecyltrimethylammonium chloride was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 1 hour. After stirring was stopped, the solution was transferred to a 50°C oven for drying. After drying for 12 hours, the obtained yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powder precursor. The yellow powder precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 5°C / min, and the temperature was increased from room temperature to 460°C and maintained at 460°C for 4 hours. After cooling to room temperature, the solution was removed and ground to obtain a black powder catalyst A1.

[0051] The physicochemical properties of catalyst A1 are listed in Table 1.

[0052] Example 2

[0053] Weigh 200 mg of formaldehyde and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 200 mg of ammonium molybdate tetrahydrate and 200 mg of glycine. Continue stirring for 1.5 h to obtain solution A.

[0054] Weigh 0.5g of polyvinyl alcohol and dissolve it in 9.5g of deionized water to obtain a polyvinyl alcohol solution; add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 1 hour, then add 200mg of ammonium sulfide and stir for 1.5 hours to obtain solution B.

[0055] 600 mg of dodecyl dimethyl tertiary amine was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 1.5 h. After stirring was stopped, the solution was transferred to a 60 °C oven for drying. After drying for 18 h, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4 °C / min, and the temperature was increased from room temperature to 530 °C and maintained at 530 °C for 3.5 h. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A2.

[0056] The physicochemical properties of catalyst A2 are listed in Table 1.

[0057] Example 3

[0058] Weigh 200 mg of glutaraldehyde and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 120 mg of molybdenum chloride and 250 mg of disodium ethylenediaminetetraacetate. Continue stirring for 2 hours to obtain solution A.

[0059] Weigh 0.4g of polyvinyl alcohol and dissolve it in 19.6g of deionized water to obtain a polyvinyl alcohol solution; add 20g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 1.5h. Then add 160mg of sodium sulfide and stir for 2h to obtain solution B.

[0060] 500 mg of hexadecyltrimethylammonium bromide was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 2 hours. After stirring was stopped, the solution was transferred to a 65°C oven for drying. After drying for 24 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 3°C / min, and the temperature was increased from room temperature to 600°C and maintained at 600°C for 3 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A3.

[0061] The physicochemical properties of catalyst A3 are listed in Table 1.

[0062] Example 4

[0063] Weigh 250 mg of succinaldehyde and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 580 mg of ammonium molybdate tetrahydrate and 250 mg of hydroxylamine hydrochloride. Continue stirring for 2.5 h to obtain solution A.

[0064] Weigh 0.4g of polyvinyl alcohol and dissolve it in 9.6g of deionized water to obtain a polyvinyl alcohol solution; add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 2 hours. Then add 300mg of ammonium sulfide and stir for 2.5 hours to obtain solution B.

[0065] 500 mg of hexadecyltrimethylammonium bromide was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 2.5 h. After stirring was stopped, the solution was transferred to a 70 °C oven for drying. After drying for 30 h, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4 °C / min, and the temperature was increased from room temperature to 670 °C and maintained at 670 °C for 2.5 h. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A4.

[0066] The physicochemical properties of catalyst A4 are listed in Table 1.

[0067] Example 5

[0068] Weigh 200 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 400 mg of ammonium molybdate and 200 mg of hydroxylamine hydrochloride. Continue stirring for 3 hours to obtain solution A.

[0069] Weigh 0.5g of polyvinyl alcohol and dissolve it in 11.5g of deionized water to obtain a polyvinyl alcohol solution; add the 12g polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 2.5h. Then add 150mg of ammonium sulfide and stir for 3h to obtain solution B.

[0070] 600 mg of dodecyl dimethyl tertiary amine was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 3 hours. After stirring was stopped, the solution was transferred to an 80°C oven for drying. After drying for 36 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4°C / min, and the temperature was increased from room temperature to 750°C and maintained at 750°C for 2 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A5.

[0071] The physicochemical properties of catalyst A5 are listed in Table 1.

[0072] Example 6

[0073] Weigh 50 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 200 mg of ammonium molybdate and 700 mg of hydroxylamine hydrochloride. Stir for 1 hour to obtain solution A.

[0074] Weigh 0.5g of polyvinyl alcohol and dissolve it in 9.5g of deionized water to obtain a polyvinyl alcohol solution. Then, add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 0.5h. Then, add 70mg of trithiocyanate and stir for 1h to obtain solution B.

[0075] 1.5g of hexadecyltrimethylammonium chloride was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 1 hour. After stirring was stopped, the solution was transferred to a 50℃ oven for drying. After drying for 12 hours, the obtained yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powder precursor. The yellow powder precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 5℃ / min, and the temperature was increased from room temperature to 460℃ and maintained at 460℃ for 4 hours. After cooling to room temperature, the solution was removed and ground to obtain a black powder catalyst A6.

[0076] The physicochemical properties of catalyst A6 are listed in Table 1.

[0077] Example 7

[0078] Weigh 70 mg of formaldehyde and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 200 mg of ammonium molybdate tetrahydrate and 600 mg of glycine. Continue stirring for 1.5 h to obtain solution A.

[0079] Weigh 0.5g of polyvinyl alcohol and dissolve it in 9.5g of deionized water to obtain a polyvinyl alcohol solution; add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 1 hour, then add 380mg of ammonium sulfide and stir for 1.5 hours to obtain solution B.

[0080] 500 mg of dodecyl dimethyl tertiary amine was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 1.5 h. After stirring was stopped, the solution was transferred to a 60 °C oven for drying. After drying for 18 h, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4 °C / min, and the temperature was increased from room temperature to 530 °C and maintained at 530 °C for 3.5 h. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A7.

[0081] The physicochemical properties of catalyst A7 are listed in Table 1.

[0082] Example 8

[0083] Weigh 50 mg of glutaraldehyde and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 150 mg of molybdenum chloride and 800 mg of disodium ethylenediaminetetraacetate. Continue stirring for 2 hours to obtain solution A.

[0084] Weigh 0.4g of polyvinyl alcohol and dissolve it in 19.6g of deionized water to obtain a polyvinyl alcohol solution; add 20g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 1.5h, then add 150mg of sodium sulfide and stir for 2h to obtain solution B.

[0085] Dissolve 800 mg of hexadecyltrimethylammonium bromide in water. After complete dissolution, add the aqueous solution dropwise to solution B while maintaining stirring. After the addition is complete, continue stirring for 2 hours. After stirring is finished, transfer the solution to a 65°C oven for drying. After drying for 24 hours, scrape off the obtained yellow flake-like precursor, grind it thoroughly, and pulverize it to obtain a yellow powdered precursor. Place the yellow powdered precursor in a clean ceramic boat and transfer it into a tube furnace under a nitrogen atmosphere. Set the heating program to 3°C / min, raise the temperature from room temperature to 600°C, and maintain it at 600°C for 3 hours. After cooling to room temperature, remove the solution and grind it to obtain a black powdered catalyst A8.

[0086] The physicochemical properties of catalyst A8 are listed in Table 1.

[0087] Comparative Example 1

[0088] Weigh 400 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 50 mg of ammonium molybdate and 50 mg of hydroxylamine hydrochloride. Continue stirring for 3 hours to obtain solution A.

[0089] Weigh 1g of polyvinyl alcohol and dissolve it in 19g of deionized water to obtain a polyvinyl alcohol solution. Add the 20g polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 0.5h. Then add 40mg of trithiocyanate and stir for 2h to obtain solution B.

[0090] 1.2 g of hexadecyltrimethylammonium chloride was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 2 hours. After stirring was stopped, the solution was transferred to a 70°C oven for drying. After drying for 24 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 5°C / min, and the temperature was increased from room temperature to 650°C and maintained at 650°C for 4 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst B1.

[0091] The physicochemical properties of catalyst B1 are listed in Table 1.

[0092] Comparative Example 2

[0093] Weigh 200 mg of tannic acid and dissolve it in 100 mL of deionized water. Stir until completely dissolved, then add 1 g of ammonium molybdate and 1 g of hydroxylamine hydrochloride. Stir for 3 h to obtain solution A.

[0094] Weigh 0.5g of polyvinyl alcohol and dissolve it in 9.5g of deionized water to obtain a polyvinyl alcohol solution. Add 10g of the polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 0.5h. Then add 600mg of trithiocyanate and stir for 2h to obtain solution B.

[0095] 600 mg of hexadecyltrimethylammonium chloride was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 2 hours. After stirring was stopped, the solution was transferred to a 70°C oven for drying. After drying for 24 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 5°C / min, and the temperature was increased from room temperature to 650°C and maintained at 650°C for 4 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst B2.

[0096] The physicochemical properties of catalyst B2 are listed in Table 1.

[0097] Comparative Example 3

[0098] Weigh 200 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 400 mg of ammonium molybdate and 200 mg of hydroxylamine hydrochloride. Continue stirring for 3 hours to obtain solution A.

[0099] Weigh 0.5g of β-cyclodextrin and dissolve it in 31.5g of deionized water to obtain an aqueous solution of β-cyclodextrin; add the 32g aqueous solution of β-cyclodextrin dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 2.5h. Then add 150mg of ammonium sulfide and stir for 3h to obtain solution B.

[0100] 600 mg of dodecyl dimethyl tertiary amine was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 3 hours. After stirring was stopped, the solution was transferred to an 80°C oven for drying. After drying for 36 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4°C / min, and the temperature was increased from room temperature to 750°C and maintained at 750°C for 2 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst B3.

[0101] The physicochemical properties of catalyst B3 are listed in Table 1.

[0102] Comparative Example 4

[0103] Weigh 200 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 400 mg of ammonium molybdate and 200 mg of hydroxylamine hydrochloride. Continue stirring for 3 hours to obtain solution A.

[0104] Weigh 0.5g of polyvinyl alcohol and dissolve it in 11.5g of deionized water to obtain a polyvinyl alcohol solution; add the 12g polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 2.5h. Then add 150mg of ammonium sulfide and stir for 3h to obtain solution B.

[0105] 600 mg of sodium dodecylbenzenesulfonate was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 3 hours. After stirring was stopped, the solution was transferred to an 80°C oven for drying. After drying for 36 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4°C / min, and the temperature was increased from room temperature to 750°C and maintained at 750°C for 2 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A5.

[0106] Comparative Example 5

[0107] Weigh 200 mg of tannic acid and dissolve it in 20 mL of deionized water. Stir until completely dissolved, then add 400 mg of ammonium molybdate and 150 mg of ammonium sulfide. Continue stirring for 3 hours to obtain solution A.

[0108] Weigh 0.5g of polyvinyl alcohol and dissolve it in 11.5g of deionized water to obtain a polyvinyl alcohol solution; add the 12g polyvinyl alcohol solution dropwise to solution A while maintaining stirring. After the addition is complete, continue stirring for 2.5h. Then add 200mg of hydroxylamine hydrochloride and stir for 3h to obtain solution B.

[0109] 600 mg of dodecyl dimethyl tertiary amine was dissolved in water. After complete dissolution, the aqueous solution was added dropwise to solution B while stirring. After the addition was complete, stirring was continued for 3 hours. After stirring was stopped, the solution was transferred to an 80°C oven for drying. After drying for 36 hours, the resulting yellow flake-like precursor was scraped off, thoroughly ground, and pulverized to obtain a yellow powdered precursor. The yellow powdered precursor was placed in a clean ceramic boat and transferred to a tube furnace under a nitrogen atmosphere. The heating program was set to 4°C / min, and the temperature was increased from room temperature to 750°C and maintained at 750°C for 2 hours. After cooling to room temperature, the precursor was removed and ground to obtain a black powdered catalyst A5.

[0110] The physicochemical properties of catalyst A5 are listed in Table 1.

[0111] Experimental Example 1

[0112] The catalysts prepared in each embodiment and comparative example were tested for metal element loading, pore volume, specific surface area, pore size and active sites. The specific test results are shown in the table below.

[0113] The metal element loading was detected using inductively coupled plasma (ICP).

[0114] Pore ​​volume, specific surface area, and pore size were measured using the BET test method.

[0115] The active sites were analyzed using X-ray absorption fine structure (EXAFS).

[0116] Table 1 Catalyst Properties

[0117] catalyst Metal loading Pore ​​volume / mL / g Specific surface area Aperture / nm Active site type A1 6.3％ 0.3 257.2 5.1 <![CDATA[Mo-SAC / MoS2]]> A2 6.7％ 0.3 232.5 4.9 <![CDATA[Mo-SAC / MoS2]]> A3 3.2％ 0.4 243.2 5.0 <![CDATA[Mo-SAC / MoS2]]> A4 17.3％ 0.3 236.7 5.1 <![CDATA[Mo-SAC / MoS2]]> A5 12.1％ 0.3 238.9 4.9 <![CDATA[Mo-SAC / MoS2]]> A6 6.1％ 0.4 240.6 5.0 <![CDATA[Mo-SAC / MoS2]]> A7 6.9％ 0.3 231.5 5.0 <![CDATA[Mo-SAC / MoS2]]> A8 3.7％ 0.3 246.2 4.9 <![CDATA[Mo-SAC / MoS2]]> B1 1％ 0.4 175.7 3.7 Mo-SAC B2 20.3％ 0.3 145.8 4.5 <![CDATA[Mo-SAC / MoS2]]> B3 11.5％ 0.4 240.2 5.0 Mo-SAC B4 11.6％ 0.3 157.7 4.9 Mo-SAC / MoS2 B5 11.9％ 0.3 236 4.9 <![CDATA[MoS2]]>

[0118] The catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to transmission electron microscopy (TEM). See details below. Figure 1 , Figure 2 and Figure 3 .Depend on Figure 1-3 It can be seen that no molybdenum sulfide streaks were observed in the catalysts prepared in Example 1 and Comparative Example 1, while significant molybdenum sulfide streaks were observed in the catalyst prepared in Comparative Example 2. This indicates that no molybdenum sulfide particle clusters occurred in the catalysts prepared in Example 1 and Comparative Example 1, and the single-atom molybdenum and nano-molybdenum sulfide were uniformly distributed and did not cover each other. However, the molybdenum sulfide particles in the catalyst prepared in Comparative Example 2 were obviously clustered.

[0119] Figure 4 These are EXAFS diagrams of the catalysts prepared in Example 1 and Comparative Example 1 of this invention. Figure 4 It can be seen that the catalyst prepared in Example 1 of this invention has characteristic peaks of molybdenum sulfide, and therefore has molybdenum sulfide active sites. Figure 4 The middle, ..., and —...—... represent the absorption peaks of Mo-S in the reference MoS2 and the substrate peak of the reference Mo foil, respectively.

[0120] Figure 5 This is an aberration-corrected electron micrograph of the catalyst prepared in Example 1 of the present invention. Figure 5 As can be seen, the bright spots in the image represent single-atom catalysts; combined with... Figure 4 It can be seen that the catalyst prepared in Example 1 of the present invention is a composite catalyst of single-atom molybdenum and nano-molybdenum sulfide.

[0121] As can be seen from the data in the table above and the accompanying figures, the metal loading in Examples 1-8 ranges from 3wt% to 19wt%. At this metal loading level, the active sites are dual active sites consisting of single-atom molybdenum and nano-sized molybdenum sulfide. Figure 1 It can be seen that no obvious molybdenum sulfide particle clusters are visible within the field of view; the metal loading of catalyst B1 prepared in Comparative Example 1 is 1%, at which point the active sites are single-atom molybdenum active sites; the metal loading of catalyst B2 prepared in Comparative Example 2 is 20.3%, at which point, although the active sites are still dual active sites of single-atom molybdenum and nano-molybdenum sulfide, the... Figure 3 It is known that molybdenum sulfide particle clusters formed, which in turn covered some of the single-atom molybdenum active sites, leading to partial deactivation of the catalyst. In Comparative Example 3, polyvinyl alcohol was replaced with cyclodextrin. The porous structure of cyclodextrin itself encapsulates each metal single atom in the cavity, improving the stability of the metal single atoms and resulting in a higher metal loading. Therefore, a single-atom catalyst was finally obtained. The surfactant added in Comparative Example 4 was an anionic surfactant. After ionization in water, the part that plays a surface-active role carries a negative charge and does not easily react with [MoS4]. 2- Coordination occurs, thus failing to regulate the size and morphology of nanoparticles. In the resulting composite catalyst, nanoparticles easily cluster and cover active sites, significantly reducing catalyst performance. Comparative Example 5 reversed the order of addition of the chelating agent and the sulfiding agent: the sulfiding agent and molybdenum salt were added directly in the first step, generating ammonium thiomolybdate, resulting in nano-molybdenum sulfide particles as the catalyst. In contrast, in Example 5, the chelating agent and molybdenum salt were added first, forming a stable chelate. This allows molybdenum to be fixed in the adsorption sites in a stable chelate form, ultimately forming a composite catalyst of single-atom molybdenum and nano-molybdenum sulfide.

[0122] Experimental Example 2

[0123] Using high-sulfur, high-metal, and high-carbon vacuum residue from Qingdao Refining & Chemical Co. (specific properties are shown in Table 2) as feedstock, the coking performance of the catalysts prepared in the above examples and comparative examples was evaluated in a 500 mL small slurry bed reactor. The process conditions used for evaluating each catalyst were identical. The reaction conditions were: reaction temperature 425℃, initial hydrogen pressure 7 MPa, stirring speed 500 r / min, 100 g of heavy oil, catalyst mass concentration (calculated as Mo) of 200 ppm (standard), and reaction time 1 h. After the reaction, the coking rate and single-pass conversion rate were calculated according to the following formulas. The evaluation results are listed in Table 3.

[0124] Toluene-insoluble matter: Weigh out clean, dry filter paper (m1), seal the reacted heavy oil inside the filter paper, and place it in a distillation apparatus until the downstream liquid is colorless and transparent. After drying the filter paper, weigh out the total mass (m2) of the filter paper, catalyst, and coke. Here, the content of toluene-insoluble matter represents the coking rate.

[0125] Single-pass conversion: VR represents vacuum residue, i.e., the fraction with a temperature >500℃. Since the feedstock is vacuum residue, it is assumed here that all vacuum residue feedstock is the fraction with a temperature >500℃. That is, the mass of (VR) before reaction = 100g.

[0126]

[0127]

[0128] Table 2 uses the properties of heavy oil (Qingdao vacuum residue).

[0129]

[0130]

[0131] Table 3 Evaluation Results of Residue Hydrocracking

[0132]

[0133] As can be seen from the data in the table above, the single-atom molybdenum and nano-molybdenum sulfide composite catalyst prepared in this invention exhibits good coking activity in heavy oil hydrogenation.

[0134] Specifically, a comparison of Comparative Examples 1 and 3 with the various embodiments and blank examples reveals that although the single-atom molybdenum catalysts prepared in Comparative Examples 1 and 3 exhibit certain catalytic activity in the hydrogenation reaction of heavy oil, with single-pass conversion rates of 56.8% and 56.2%, respectively, their coking performance is poor, with coking rates of 1.6% and 2.6%, respectively. This is because, compared with composite catalysts, the single-atom molybdenum catalysts have weaker adsorption capacity for heavy oil macromolecules, while composite catalysts can utilize the molybdenum sulfide nanoparticles to enhance the adsorption capacity of heavy oil macromolecules, effectively promoting the consumption of activated hydrogen at molybdenum single-atom sites, thus playing a synergistic role.

[0135] Comparisons of Comparative Examples 2 and 4 with the various examples and blank examples show that the composite catalysts with cluster formation prepared in Comparative Examples 2 and 4 exhibit certain catalytic activity in the hydrogenation reaction, with single-pass conversion rates of 58.4% and 57.8%, respectively. However, their coking performance is poor, with coking rates of 1.9% and 2.3%, respectively. This is because the clusters of molybdenum sulfide particles cover part of the active sites, leading to partial deactivation of the catalyst.

[0136] As can be seen from the comparison between Comparative Example 5 and the various embodiments and blank examples, the nano-molybdenum disulfide catalyst prepared in Comparative Example 5 exhibits certain catalytic activity in the hydrogenation reaction, with a single-pass conversion rate of 57.4%. However, the coking performance of this nano-molybdenum disulfide catalyst is somewhat inferior to that of the composite catalyst, with a coking rate of 1.4%. This is because the single-atom active sites in the composite catalyst have a higher activation efficiency than those in the molybdenum disulfide catalyst.

[0137] In summary, the high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst provided by this invention has excellent hydrogenation activity and exhibits good catalytic activity in heavy oil hydrogenation reaction. The single-pass conversion rate is basically distributed between 63% and 64.5%, and the coke production rate is distributed between 0.2% and 0.7%.

[0138] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a high-efficiency composite catalyst for heavy oil hydrogenation consisting of single-atom molybdenum and nano-molybdenum sulfide, characterized in that, Includes the following steps: 1) Mix the aqueous solution of the crosslinking agent, the molybdenum salt, and the chelating agent to obtain solution A; 2) After mixing the polyvinyl alcohol solution with solution A, add the vulcanizing agent and mix well to obtain solution B; 3) After mixing the aqueous solution of the cationic surfactant with the solution B, the mixture is dried and pyrolyzed to obtain a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst. The molybdenum loading in the high-efficiency heavy oil hydrotreating single-atom molybdenum and nano-molybdenum sulfide composite catalyst is 3wt%-19wt%. The crosslinking agent is selected from compounds containing carbonyl groups; The chelating agent is selected from at least one of glycine, disodium ethylenediaminetetraacetate, and hydroxylamine hydrochloride.

2. The preparation method according to claim 1, characterized in that, The mass ratio of polyvinyl alcohol in the polyvinyl alcohol solution to the crosslinking agent in the aqueous solution of the crosslinking agent is 1-10.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the cationic surfactant to the polyvinyl alcohol in the polyvinyl alcohol solution is 1-3.

4. The preparation method according to claim 1, characterized in that, The molybdenum salt, calculated as molybdenum element, has a molar ratio of chelating agent to molybdenum salt of 1-10.

5. The preparation method according to claim 1, characterized in that, The vulcanizing agent, calculated as sulfur, and the molybdenum salt, calculated as molybdenum, have a molar ratio of 1-5 of the vulcanizing agent and the molybdenum salt.

6. The preparation method according to claim 1, characterized in that, In step 3), the drying temperature is 50-80℃ and the time is 12-36 h.

7. The preparation method according to claim 1, characterized in that, In step 3), the pyrolysis temperature is 450-750℃, the time is 2-4h, the heating rate is 1-5℃ / min, and the pyrolysis environment is a nitrogen atmosphere.

8. The preparation method according to claim 1, characterized in that, The crosslinking agent is selected from at least one of tannic acid, glutaraldehyde, formaldehyde, and succinaldehyde; The cationic surfactant is selected from at least one of hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, dodecyldimethylbenzylammonium chloride, and dodecyldimethyl tertiary amine.

9. The preparation method according to claim 1, characterized in that, The molybdenum salt is selected from at least one of ammonium molybdate, sodium molybdate, and molybdenum chloride; and / or The vulcanizing agent is selected from at least one of trithiocyanate, ammonium sulfide, sodium sulfide and elemental sulfur.

10. The preparation method according to claim 8, characterized in that, The crosslinking agent is tannic acid.

11. The preparation method according to claim 8, characterized in that, The cationic surfactant is hexadecyltrimethylammonium chloride.

12. A method for hydrogenating heavy oil, characterized in that, Includes the following steps: After the catalyst is mixed evenly with FCC catalytic cracking diesel, it is added to low-quality heavy oil for hydrogenation reaction; The catalyst is a high-efficiency heavy oil hydrogenation single-atom molybdenum and nano-molybdenum sulfide composite catalyst prepared by the preparation method according to any one of claims 1-11.

13. The method for hydrogenating heavy oil as described in claim 12, characterized in that, The catalyst, calculated by metal element, has a mass ratio of 50-1000 μg / g to the inferior heavy oil.

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