Iron sulfide catalyst for hydrocracking of heavy oil and use thereof

Abstract

This application relates to the fields of petroleum processing catalysts and solid waste resource utilization technology, specifically disclosing an iron sulfide catalyst for heavy oil hydrocracking and its application. The active component of this iron sulfide catalyst for heavy oil hydrocracking includes non-stoichiometric iron sulfide Fe obtained from coal combustion dust through magnetic separation. 1‑x S, where x ≤ 0.2. The iron sulfide catalyst Fe for heavy oil hydrocracking of this application. 1‑x S has a unique hexagonal crystal structure and surface properties. When used as a catalyst for heavy oil hydrocracking, it has significantly better catalytic efficiency than traditional hydrocracking catalysts, lower cost, longer service life, and stronger resistance to carbon buildup.

Description

Technical Field

[0001] This application relates to the fields of petroleum processing catalysts and solid waste resource utilization technology, and more specifically, it relates to an iron sulfide catalyst for heavy oil hydrocracking and its application. Background Technology

[0002] With the increasing depletion of global light crude oil resources, the efficient conversion of heavy oils (such as vacuum residue and oil sands bitumen) has become crucial for the sustainable development of the refining industry. Hydrocracking technology, as the core process for converting heavy oils into high-value light fuels, relies heavily on the catalysts used for its performance.

[0003] Currently, the active components of heavy oil hydrocracking catalysts widely used in industry are mainly transition metal sulfides from Group VIB and Group VIII, typically represented by Ni-Mo / Al2O3 and Co-Mo / Al2O3 systems. Although these catalysts possess high hydrocracking activity and cracking capacity, their inherent technical shortcomings are becoming increasingly apparent in practical industrial applications, especially when processing low-quality heavy oil with high residual carbon, high metal, and high sulfur and nitrogen content. First, the raw materials upon which the active core of existing catalysts depends are expensive and significantly affected by fluctuations in the international market, directly leading to high catalyst manufacturing costs. Second, when processing low-quality heavy oil with high residual carbon values ​​and high metal content, large molecules such as gums and asphaltenes easily coke and deposit carbon on the catalyst surface and in the pores, causing the active sites to be covered and rapidly deactivated. Metal impurities such as vanadium and nickel will deposit on the catalyst, poisoning the active centers and clogging the pores. Together, these factors result in the short service life of traditional catalysts under harsh operating conditions, requiring frequent regeneration or replacement, increasing operating costs and plant downtime losses. In addition, the preparation of traditional catalysts usually involves complex chemical impregnation, high-temperature calcination, and other steps, which are energy-intensive and may generate metal-containing wastewater and exhaust gas, putting significant environmental pressure on the industry.

[0004] As a major coal consumer, my country generates hundreds of millions of tons of coal combustion dust annually from coal-fired power plants and other sources. This dust contains various forms of iron compounds, which are typically treated as solid waste, occupying land and posing environmental risks. Although the iron in this dust theoretically possesses catalytic potential, it usually exists as a mixture of multiple phases, with a wide particle size distribution and contaminated surfaces, resulting in low and uncontrollable catalytic activity, making it difficult to directly apply to demanding hydrocracking reactions.

[0005] Therefore, there is an urgent need in this field to develop a heavy oil hydrocracking catalyst that combines low cost, high activity, and good stability, while also enabling the high-value utilization of industrial solid waste, which would have significant economic and social benefits. Summary of the Invention

[0006] In order to reduce the cost of hydrocracking catalysts, improve their activity and stability, and increase the efficiency of heavy oil hydrocracking, this application provides an iron sulfide catalyst for heavy oil hydrocracking and its application.

[0007] In a first aspect, this application provides an iron sulfide catalyst for heavy oil hydrocracking and its application, employing the following technical solution:

[0008] An iron sulfide catalyst for heavy oil hydrocracking, the active component comprising non-stoichiometric iron sulfide Fe obtained from coal combustion dust via magnetic separation. 1-x S, where x≤0.2.

[0009] The inventors, through research using coal combustion dust as a catalyst source, obtained iron sulfide Fe with a non-stoichiometric ratio through a series of physical separation processes such as magnetic separation. 1-x The catalyst with S as the active component was found to contain naturally occurring iron sulfides, Fe. 1-x Under specific combustion and separation conditions, FeS tends to be a stable phase with a hexagonal crystal structure. After comparative experimental analysis, it was found that its unique crystal structure and surface properties make it exhibit significantly better catalytic activity and anti-carbon deposition ability than conventionally chemically synthesized FeS in hydrocracking reactions.

[0010] Optionally, the Fe 1-x S has a hexagonal crystal structure with lattice parameters a = 0.345-0.348 nm and c = 0.573-0.576 nm.

[0011] Optionally, the Fe 1-x S has a particle size of 10-30 μm, a purity of ≥95%, and a specific surface area of ​​15-25 m². 2 / g.

[0012] Secondly, this application provides a method for preparing an iron sulfide catalyst for heavy oil hydrocracking, employing the following technical solution:

[0013] A method for preparing an iron sulfide catalyst for heavy oil hydrocracking includes the following steps:

[0014] S1: Combustion of coal produces coal combustion dust containing iron and sulfur compounds;

[0015] S2: Magnetic separation of coal combustion dust is carried out. First, a first-stage magnetic separation is performed with a magnetic field strength of 0.3-0.5T. Then, a second-stage magnetic separation is performed with a magnetic field strength of 0.8-1.2T. Finally, a third-stage magnetic separation is performed with a magnetic field strength of 1.5-2.0T to obtain primary iron sulfides, which are then ultrasonically cleaned to obtain the final product.

[0016] By adopting the above technical solution, the inventors achieved efficient enrichment and purification of the target active component through an integrated process of combustion, multi-stage magnetic separation and ultrasonic cleaning. Multi-stage magnetic separation effectively removes impurities and efficiently recovers the target product based on the subtle differences in the magnetic properties of the material. Ultrasonic cleaning can remove amorphous substances and ash adhering to the particle surface, further exposing the active sites of the target iron sulfide.

[0017] Optionally, the ultrasonic cleaning frequency is 40-60kHz and the power is 500-800W.

[0018] Optionally, the coal in step S1 is pre-oxidized before combustion, specifically including the following steps: treating the coal in an atmosphere of 150-250℃ and oxygen concentration of 5-10% for 1-2 hours.

[0019] By adopting the above technical solution, pre-oxidation alters the occurrence state of iron minerals in coal, making it easier for Fe to form the target crystal form during subsequent combustion. 1-x S makes the iron sulfide catalyst obtained after pre-oxidation have better catalytic activity and anti-carbon deposition ability.

[0020] Optionally, the obtained iron sulfide catalyst may undergo gradient acid post-treatment, specifically including the following steps:

[0021] S1: In an inert gas atmosphere, the iron sulfide catalyst is added to an oxalic acid solution, heated and stirred in a water bath at 65-75°C, washed and dried, and then added to a composite acid solution of citric acid and phosphoric acid. The solution is heated and stirred in a water bath at 55-65°C, washed and dried to obtain an acid-treated iron sulfide catalyst.

[0022] S2: The acid-treated iron sulfide catalyst is calcined at 350-450℃ in an inert gas atmosphere for 2-3 hours to obtain the modified iron sulfide catalyst.

[0023] By adopting the above technical solution, the inventors used a gradient acid treatment, first using the strong chelating acid oxalic acid to preferentially dissolve the product iron sulfide Fe. 1-x The amorphous impurities and some unstable surface phases in S effectively clean and activate the inherent pore surface, greatly improving the diffusion and mass transfer capacity of heavy oil macromolecules during heavy oil hydrocracking and thus increasing catalytic efficiency.

[0024] Furthermore, citric acid and phosphoric acid, as a complex acid, allow citric acid to further clean, refine, and stabilize iron sulfides (Fe). 1-xThe surface structure of the S catalyst provides a superior surface environment for the anchoring of phosphoric acid. On the other hand, phosphoric acid forms a monolayer or sub-monolayer iron-phosphorus-O structure, chemically anchored to the catalyst surface via PO-Fe covalent bonds. After subsequent mild calcination, highly stable L-acid sites are formed, rather than existing as bulk impurities. The introduction of L-acid sites significantly promotes the formation of iron sulfides (Fe). 1-x The cracking ability of S in the hydrocracking reaction of heavy oil not only significantly improves the conversion rate of catalyst hydrocracking and the yield of light oil, but also further enhances the catalyst's resistance to carbon buildup and extends its service life.

[0025] Optionally, the concentration of oxalic acid solution in step S1 is 0.1-0.3 mol / L, the concentration of citric acid in the composite acid solution is 0.3-0.5 mol / L, and the concentration of phosphoric acid is 0.1-0.3 mol / L.

[0026] By adopting the above technical solution, the entire gradient acid treatment process is carried out under an inert gas protective atmosphere. The acid solution concentration is lower, the treatment temperature and time are more moderate, and the calcination conditions are also more gentle, effectively preventing damage to iron sulfides (Fe). 1-x This process effectively preserves the structure and composition of sulfur while preventing the formation of iron oxide impurities, resulting in a significant improvement in the iron sulfide Fe content. 1-x Catalytic activity of S catalyst.

[0027] Thirdly, the iron sulfide catalyst of this application for heavy oil hydrocracking is applied to heavy oil hydrocracking.

[0028] Optionally, the amount of the iron sulfide catalyst is 2-4% of the heavy oil feedstock.

[0029] Optionally, the method for applying the iron sulfide catalyst for heavy oil hydrocracking includes the following steps: mixing the iron sulfide catalyst with heavy oil feedstock, carrying out hydrocracking reaction in the presence of hydrogen, and obtaining light distillate products after separation.

[0030] Optionally, the hydrocracking reaction conditions are: hydrogen pressure 8-12 MPa, reaction temperature 380-420℃, hydrogen to feedstock volume ratio 800-1200:1, and reaction time 2-4 h.

[0031] By adopting the above technical solution, the iron sulfide catalyst of this application not only exhibits higher activity than traditional precious metal catalysts in heavy oil hydrocracking, but also has a longer service life and a lower tendency to carbon deposition due to its unique surface properties and structural stability.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application utilizes iron sulfide Fe obtained from the high-value resource utilization of coal combustion dust. 1-x S has a unique hexagonal crystal structure and surface properties, achieving a conversion rate of over 85% and a light oil yield of over 80% in heavy oil hydrocracking, with performance significantly superior to traditional catalysts and FeS synthesized by ordinary chemicals.

[0034] 2. The iron sulfide Fe of this application 1-x When used as a catalyst in the hydrocracking reaction of heavy oil, S has a longer service life and stronger resistance to carbon buildup.

[0035] 3. This application uses inexpensive industrial solid waste as raw material, which reduces costs by more than 80% compared to traditional Ni-Mo and Co-Mo catalysts. At the same time, it solves the problem of solid waste disposal, is green and environmentally friendly, and conforms to the concept of circular economy. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments and comparative examples. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present application are all commercially available common products.

[0037] Example 1

[0038] An iron sulfide catalyst for heavy oil hydrocracking, the preparation method of which includes the following steps:

[0039] S1: 100g of coal is pre-oxidized at 200℃ and in an atmosphere with an oxygen concentration of 8% for 1.5h to obtain pre-treated coal;

[0040] S2: The pretreated coal is burned in a muffle furnace at 700℃ and atmospheric pressure, and the generated coal combustion dust is fully collected.

[0041] S3: Multi-stage magnetic separation is performed on coal combustion dust. First, a first-stage magnetic separation is performed with a magnetic field strength of 0.4T to remove most of the dust and weakly magnetic impurities. Then, a second-stage magnetic separation is performed with a magnetic field strength of 0.9T to collect the target iron sulfide enrichment. Finally, a third-stage magnetic separation is performed with a magnetic field strength of 1.8T to remove strongly magnetic impurities (such as Fe3O4) and obtain the primary iron sulfide.

[0042] S4: The primary iron sulfide samples were ultrasonically cleaned for 30 min at a frequency of 50 kHz and a power of 600 W, and then dried to obtain the target iron sulfide catalyst. The catalyst was characterized by XRD, BET, SEM, and XPS. It is a hexagonal Fe catalyst. 0.9 S, with lattice parameters a=0.3452nm, c=0.5735nm, particle size of 10-30μm, average particle size of 18μm, purity of 96.5%, and specific surface area of ​​21.5m².2 / g.

[0043] Example 2

[0044] An iron sulfide catalyst for heavy oil hydrocracking, the preparation method of which includes the following steps:

[0045] S1: 100g of coal is pre-oxidized at 150℃ and in an atmosphere with an oxygen concentration of 5% for 2 hours to obtain pre-treated coal;

[0046] S2: The pretreated coal is burned in a muffle furnace at 600℃ and atmospheric pressure, and the generated coal combustion dust is fully collected.

[0047] S3: Multi-stage magnetic separation is performed on coal combustion dust. First, a first-stage magnetic separation is performed with a magnetic field strength of 0.3T to remove most of the dust and weakly magnetic impurities. Then, a second-stage magnetic separation is performed with a magnetic field strength of 0.8T to collect the target iron sulfide enrichment. Finally, a third-stage magnetic separation is performed with a magnetic field strength of 1.5T to remove strongly magnetic impurities (such as Fe3O4) and obtain the initial screened iron sulfide.

[0048] S4: The primary iron sulfide samples were ultrasonically cleaned for 30 min at a frequency of 60 kHz and a power of 800 W, and then dried to obtain the target iron sulfide catalyst. The catalyst was characterized by XRD, BET, SEM, and XPS. It is a hexagonal Fe catalyst. 0.86 S, with lattice parameters a=0.3466nm, c=0.5749nm, particle size of 10-30μm, average particle size of 15μm, purity of 96.5%, and specific surface area of ​​25m². 2 / g.

[0049] Example 3

[0050] An iron sulfide catalyst for heavy oil hydrocracking, the preparation method of which includes the following steps:

[0051] S1: 100g of coal is pre-oxidized at 250℃ in an atmosphere with an oxygen concentration of 10% for 1 hour to obtain pre-treated coal;

[0052] S2: The pretreated coal is burned in a muffle furnace at 800℃ and atmospheric pressure, and the generated coal combustion dust is fully collected.

[0053] S3: Multi-stage magnetic separation is performed on coal combustion dust. First, a first-stage magnetic separation is performed with a magnetic field strength of 0.5T to remove most of the dust and weakly magnetic impurities. Then, a second-stage magnetic separation is performed with a magnetic field strength of 1.2T to collect the target iron sulfide enrichment. Finally, a third-stage magnetic separation is performed with a magnetic field strength of 2.0T to remove strongly magnetic impurities (such as Fe3O4) and obtain the initial screened iron sulfide.

[0054] S4: The primary iron sulfide samples were ultrasonically cleaned for 30 min at a frequency of 40 kHz and a power of 500 W, and then dried to obtain the target iron sulfide catalyst. The catalyst was characterized by XRD, BET, SEM, and XPS. It is a hexagonal Fe catalyst. 0.8 S, with lattice parameters a=0.3478nm, c=0.5757nm, particle size of 10-30μm, average particle size of 23μm, purity of 95.8%, and specific surface area of ​​15m². 2 / g.

[0055] Example 4

[0056] An iron sulfide catalyst for heavy oil hydrocracking differs from Example 1 in that the iron sulfide catalyst obtained in step S4 undergoes a gradient acid post-treatment, specifically including the following steps:

[0057] S1: In a nitrogen atmosphere, the iron sulfide catalyst was added to a 0.3 mol / L oxalic acid solution at a feed-to-liquid ratio of 1:10, heated and stirred in a water bath at 75°C for 0.5 h, and then washed and dried.

[0058] S2: The dried iron sulfide catalyst from step S1 was added to a composite acid solution of citric acid and phosphoric acid at a ratio of 1:10. The concentration of citric acid was 0.5 mol / L and the concentration of phosphoric acid was 0.3 mol / L. The mixture was heated and stirred in a water bath at 55°C for 2 hours. After washing and drying, the acid-treated iron sulfide catalyst was obtained.

[0059] S3: The acid-treated iron sulfide catalyst was calcined at 350°C under a nitrogen atmosphere for 3 hours to obtain the modified iron sulfide catalyst. All other steps were the same as in Example 1.

[0060] Example 5

[0061] An iron sulfide catalyst for heavy oil hydrocracking differs from Example 1 in that the iron sulfide catalyst obtained in step S4 undergoes a gradient acid post-treatment, specifically including the following steps:

[0062] S1: In a nitrogen atmosphere, the iron sulfide catalyst was added to a 0.2 mol / L oxalic acid solution at a feed-to-liquid ratio of 1:10, heated and stirred in a water bath at 70°C for 1 hour, and then washed and dried.

[0063] S2: The dried iron sulfide catalyst from step S1 is added to a composite acid solution of citric acid and phosphoric acid at a ratio of 1:10. The concentration of citric acid is 0.3 mol / L and the concentration of phosphoric acid is 0.1 mol / L. The mixture is heated and stirred in a water bath at 65°C for 1 hour. After washing and drying, the acid-treated iron sulfide catalyst is obtained.

[0064] S3: The acid-treated iron sulfide catalyst was calcined at 400°C under a nitrogen atmosphere for 2.5 h to obtain the modified iron sulfide catalyst. All other steps were the same as in Example 1.

[0065] Example 6

[0066] An iron sulfide catalyst for heavy oil hydrocracking differs from Example 1 in that the iron sulfide catalyst obtained in step S4 undergoes a gradient acid post-treatment, specifically including the following steps:

[0067] S1: In a nitrogen atmosphere, the iron sulfide catalyst was added to a 0.1 mol / L oxalic acid solution at a feed-to-liquid ratio of 1:10, heated and stirred in a water bath at 65°C for 1.5 h, and then washed and dried.

[0068] S2: The dried iron sulfide catalyst from step S1 is added to a composite acid solution of citric acid and phosphoric acid at a ratio of 1:10. The concentration of citric acid is 0.4 mol / L and the concentration of phosphoric acid is 0.2 mol / L. The mixture is heated and stirred in a water bath at 60°C for 1.5 h. After washing and drying, the acid-treated iron sulfide catalyst is obtained.

[0069] S3: The acid-treated iron sulfide catalyst was calcined at 450°C under a nitrogen atmosphere for 2 hours to obtain the modified iron sulfide catalyst. All other steps were the same as in Example 1.

[0070] Example 7

[0071] An iron sulfide catalyst for heavy oil hydrocracking differs from Example 1 in that the coal is not pre-oxidized in step S1, while all other steps are the same as in Example 1.

[0072] Example 8

[0073] An iron sulfide catalyst for heavy oil hydrocracking, differing from Example 4 in that the iron sulfide catalyst is not treated with oxalic acid, specifically including the following steps:

[0074] S1: In a nitrogen atmosphere, the iron sulfide catalyst was added to a composite acid solution of citric acid and phosphoric acid at a feed-to-liquid ratio of 1:10. The concentration of citric acid was 0.5 mol / L and the concentration of phosphoric acid was 0.3 mol / L. The mixture was heated and stirred in a water bath at 55°C for 2 hours. After washing and drying, the acid-treated iron sulfide catalyst was obtained.

[0075] S2: The acid-treated iron sulfide catalyst was calcined at 350°C under a nitrogen atmosphere for 3 hours to obtain the modified iron sulfide catalyst. All other steps were the same as in Example 4.

[0076] Example 9

[0077] An iron sulfide catalyst for heavy oil hydrocracking, differing from Example 4 in that the iron sulfide catalyst is not subjected to complex acid treatment, specifically including the following steps:

[0078] S1: In a nitrogen atmosphere, the iron sulfide catalyst was added to a 0.3 mol / L oxalic acid solution at a feed-to-liquid ratio of 1:10, heated and stirred in a water bath at 75°C for 0.5 h, and then washed and dried to obtain the acid-treated iron sulfide catalyst.

[0079] S2: The acid-treated iron sulfide catalyst was calcined at 350°C under a nitrogen atmosphere for 3 hours to obtain the modified iron sulfide catalyst. All other steps were the same as in Example 4.

[0080] The application of the iron sulfide catalyst for heavy oil hydrocracking in this application.

[0081] Application Example 1

[0082] A method for hydrocracking heavy oil specifically includes the following steps:

[0083] 100g of vacuum residue (density 0.95g / cm³, carbon residue 12%) was used as raw material. 3g of the iron sulfide catalyst for heavy oil hydrocracking prepared in Example 1 was added and mixed evenly. The mixture was then placed in a high-pressure reactor. After replacing the air in the reactor with hydrogen, hydrogen was introduced to the initial cold pressure. The temperature and pressure were then increased to a total pressure of 10MPa and a temperature of 400℃. The hydrogen-to-oil volume ratio was 1000:1. The mixture was stirred and reacted for 3 hours under these conditions. After the reaction was completed, the temperature was lowered and the pressure was released. The catalyst and liquid product were separated. The liquid product was distilled to obtain a light fraction.

[0084] Application Example 2-9

[0085] A method for hydrocracking heavy oil differs from Application Example 1 in that the source of the iron sulfide catalyst used for hydrocracking heavy oil is shown in Table 1, while the other steps are the same as in Application Example 1.

[0086] Table 1

[0087]

[0088] Application Example 10

[0089] A method for hydrocracking heavy oil differs from Application Example 1 in that the amount of iron sulfide catalyst for hydrocracking heavy oil prepared in Example 1 is 2g, while the other steps are the same as in Application Example 1.

[0090] Application Example 11

[0091] A method for hydrocracking heavy oil differs from Application Example 1 in that the amount of iron sulfide catalyst prepared for hydrocracking of heavy oil in Example 1 is 2.5 g, while the other steps are the same as in Application Example 1.

[0092] Application Example 12

[0093] A method for hydrocracking heavy oil differs from Application Example 1 in that the amount of iron sulfide catalyst prepared for hydrocracking of heavy oil in Example 1 is 4g, while the other steps are the same as in Application Example 1.

[0094] Comparative Application Example 1

[0095] A method for hydrocracking heavy oil differs from Application Example 1 in that the iron sulfide catalyst prepared in Example 1 for hydrocracking heavy oil is replaced with an equal mass of industrial-grade Ni-Mo / Al2O3 hydrocracking catalyst (selected from Sinopec Catalyst Co., Ltd., RN-32). All other steps are the same as in Application Example 1.

[0096] Comparative Application Example 2

[0097] A method for hydrocracking heavy oil differs from Application Example 1 in that the iron sulfide catalyst for hydrocracking heavy oil prepared in Example 1 is replaced with an equal mass of stoichiometric FeS powder synthesized by coprecipitation. All other steps are the same as in Application Example 1.

[0098] Performance testing

[0099] The light fractions of the products obtained by the heavy oil hydrocracking method of Application Examples 1-12 and Comparative Application Examples 1-2 were subjected to the following relevant performance tests. Three sets of routine experiments were conducted for each test group, and the average value of the three sets of experimental results was calculated as the final result and recorded in Table 2.

[0100] 1. Conversion rate: Calculated using simulated distillation methods;

[0101] 2. Catalyst life: Tested through continuous operation experiments;

[0102] 3. Distillation range distribution: Tested according to ASTM D2887;

[0103] 4. Sulfur and nitrogen content: Tested according to ASTM D5453 / D4629;

[0104] 5. Carbon residue value: Tested according to ASTM D524.

[0105] Table 2

[0106]

[0107] As can be seen from the performance test results in Table 2, the iron sulfide Fe obtained by the physical separation process of coal combustion dust in this application 1-x When FeS is used as a catalyst for heavy oil hydrocracking, compared with traditional industrial-grade Ni-Mo / Al2O3 hydrocracking catalysts (Comparative Application Example 1) and stoichiometric FeS synthesized by coprecipitation (Comparative Application Example 2), it not only significantly improves the hydrocracking reaction efficiency and product yield, but also has a longer service life and a lower tendency to carbon deposition. This indicates that the FeS with a specific non-stoichiometric ratio and hexagonal crystal form obtained from coal combustion dust in this application... 1-x S, whose catalytic nature differs from conventionally understood FeS, shows, according to XPS results, that the catalyst surface of this invention contains Fe. 2+ / Fe 3+ The proportion (4.2) was also much higher than that of the comparative application example 2 (2.1), which may be the underlying reason for its higher activity.

[0108] Based on the test results of Application Examples 1-3 and 10-11, it can be seen that the iron sulfide catalyst Fe of this application... 1-x When the dosage of S is 2-4% of the heavy oil feedstock, it can exhibit the best catalytic activity, and the best effect is achieved when the dosage is 2.5%.

[0109] The performance test results of Application Examples 1 and 7 show that the catalyst used in Application Example 7, which was not pre-oxidized, resulted in reduced hydrocracking reaction efficiency and product yield, as well as a significantly reduced catalyst lifetime. This is because pre-oxidation alters the occurrence state of iron minerals in coal, making it easier for Fe to form the target crystal form during subsequent combustion. 1-x S makes the iron sulfide catalyst obtained after pre-oxidation have better catalytic activity and anti-carbon deposition ability.

[0110] The performance test results from Application Examples 1, 4-6, and 8-9 show that the modified iron sulfide catalyst obtained by post-treatment modification with gradient acids exhibits further improved catalytic efficiency and product yield, with lower impurity content. This is because the use of the strong chelating acid oxalic acid preferentially dissolves the iron sulfide product Fe. 1-x The amorphous impurities and partially unstable surface phases in S effectively clean and activate the inherent pore surfaces, significantly improving the diffusion and mass transfer capabilities of heavy oil macromolecules during heavy oil hydrocracking and thus enhancing catalytic efficiency. Furthermore, citric acid and phosphoric acid, acting as a complex acid, further clean, refine, and stabilize iron sulfides (Fe). 1-xThe surface structure of the S catalyst provides a superior surface environment for the anchoring of phosphoric acid. Phosphoric acid forms highly stable L-acid sites on the catalyst surface through the formation of monolayer or sub-monolayer iron-phosphorus-O structures, rather than existing as bulk impurities. This significantly promotes the formation of iron sulfides (Fe). 1-x The cracking ability of S in the hydrocracking reaction of heavy oil not only significantly improves the conversion rate of catalyst hydrocracking and the yield of light oil, but also further enhances the catalyst's resistance to carbon buildup and extends its service life.

[0111] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An iron sulfide catalyst for hydrocracking of heavy oil, characterized by, The active ingredient comprises non-stoichiometric iron sulfide Fe 1-x S, wherein x≤0.2, the Fe 1-x S is a hexagonal crystal structure, the lattice parameters a=0.345-0.348nm, c=0.573-0.576nm, the particle size is 10-30μm, the purity≥95%, the specific surface area is 15-25m 2 / g, the preparation method of the iron sulfide catalyst for heavy oil hydrocracking comprises the following steps: S1: the coal is pre-oxidized at 150-250 DEG C for 1-2 hours in an atmosphere with oxygen concentration of 5-10%, and then combusted at 600-800 DEG C under normal pressure in a muffle furnace to generate coal combustion dust containing iron and sulfur compounds; S2: the coal combustion dust is subjected to magnetic separation, first subjected to first-stage magnetic separation in a magnetic field with intensity of 0.3-0.5 T, then subjected to second-stage magnetic separation in a magnetic field with intensity of 0.8-1.2 T, and finally subjected to third-stage magnetic separation in a magnetic field with intensity of 1.5-2.0 T to obtain primary-screened iron and sulfur compounds, which are subjected to ultrasonic cleaning, added into 0.1-0.3 mol / L oxalic acid solution in an inert gas atmosphere, heated and stirred in a water bath at 65-75 DEG C, washed, dried, added into a composite acid solution of 0.3-0.5 mol / L citric acid and 0.1-0.3 mol / L phosphoric acid, heated and stirred in a water bath at 55-65 DEG C, washed, dried, and finally obtained as acid-treated iron and sulfur compound catalyst; and the acid-treated iron and sulfur compound catalyst is calcined at 350-450 DEG C in an inert gas atmosphere for 2-3 hours to obtain the catalyst.

2. The iron sulfide catalyst for hydrocracking of heavy oil as claimed in claim 1 is applied to hydrocracking of heavy oil, characterized in that, The amount of the iron and sulfur compound catalyst is 2-4% of the heavy oil raw material.

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