A method for rejuvenation of hydrocracking spent catalyst

Abstract

The application provides a kind of revivification method of hydrocracking waste catalyst, with hydrocracking waste catalyst as raw material, on the basis of not destroying catalyst forming structure, according to saturated water absorption, different proportion of inorganic acid-organic acid-organic ligand mixed solution is prepared and treated by solvent induced coordination method, the polychaete organic ligand and organic acid in mixed solution are coordinated with dissolved active metal to generate metal-organic complex, re-impregnation process is carried out in micro excess solution, without filtration and avoiding the phenomenon of metal loss caused in drying process, without re-shaping treatment and additional carrier and metal, realizing the recycling of hydrocracking waste catalyst, and effectively improving the hydrocracking reaction performance of catalyst. The application improves resource utilization, simplifies process treatment process, greatly reduces energy consumption, effectively saves cost, realizes the sustainable utilization of waste resources.

Description

Technical Field

[0001] This invention relates to a method for reactivating spent hydrocracking catalysts, belonging to the field of spent catalyst recycling technology. Background Technology

[0002] Hydrocracking is an important secondary petroleum processing technology, suitable for processing medium and heavy crude oils, and widely used worldwide. The core of hydrocracking technology is the hydrocracking catalyst; its activity, selectivity, and stability directly affect product distribution, properties, and the plant's production efficiency. However, after multiple regenerations and uses, the activity and selectivity of hydrocracking catalysts gradually decrease during use, eventually failing to meet industrial production requirements and generating a large amount of spent catalyst.

[0003] Currently, the main methods for treating spent hydrocracking catalysts include landfill and metal recovery. Landfilling not only wastes resources but also causes environmental pollution. Research on the disposal of spent hydrocracking catalysts largely focuses on developing technologies to recover valuable metals from them. Metal recovery technologies are typically divided into hydrometallurgical processes, pyrometallurgical processes, and combined hydrometallurgical and pyrometallurgical processes. These processes involve pretreatment (grinding, roasting, etc.), acid-base leaching, extraction, and purification to extract valuable metals such as molybdenum, nickel, vanadium, cobalt, and platinum from the spent catalysts. However, these processes require excessively high roasting temperatures, resulting in high energy consumption and the generation of large amounts of harmful gases. Furthermore, they suffer from low overall leaching rates of valuable metals, low recovery efficiency, and difficulty in handling residual organic matter and silica-alumina slag in the waste liquid, all contributing to significant environmental pollution and hindering the adherence to the principles of reduction, resource recovery, and harmlessness in solid waste pollution prevention and control. Therefore, the idea of ​​revitalizing spent catalysts through chemical methods has become a research hotspot, offering a way to turn waste into treasure and harm into benefit while protecting the environment, achieving the sustainable utilization of waste resources. CN104549492A discloses a method for the complete recovery and reuse of spent hydrocracking catalyst, including high-temperature roasting, crushing and sieving, hydrothermal treatment with organic acid, followed by molding, drying, and roasting to obtain a restored hydrocracking catalyst, achieving green and environmentally friendly recycling of spent catalysts. CN112093809A discloses a method for treating spent MTP catalyst, using inorganic and organic acids to acidify the fine powder of roasted spent catalyst, removing metal impurities while increasing the silicon-aluminum ratio. It is evident that current methods for recovering and reusing revitalized spent catalysts mainly involve using excess acid and alkali solutions for pulping, filtration and washing, drying and roasting, and then re-molding. However, the filtration and washing operations lead to the loss of metal components, and the subsequent roasting process causes the active metal to re-aggregate and grow. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reactivating spent hydrocracking catalysts. The method uses spent hydrocracking catalysts as raw materials and, without damaging the catalyst's structure, processes them using a solvent-induced coordination method by preparing mixed solutions of inorganic acid, organic acid, and organic ligands in different proportions. This method requires no additional support or metals, is simple and time-saving, achieves the recycling of spent hydrocracking catalysts, and effectively improves the catalyst's hydrocracking reaction performance.

[0005] The reactivation method for spent hydrocracking catalyst of the present invention specifically includes the following steps:

[0006] (1) The spent catalyst particles from hydrocracking were roasted in air to remove carbon deposits;

[0007] (2) Measure the saturated water absorption of the catalyst after calcination, and prepare a mixed solution of inorganic acid, organic acid and organic ligand according to the saturated water absorption.

[0008] (3) The mixed solution is added dropwise to the calcined catalyst obtained in step (1) until a uniform liquid film is covered on the surface of the catalyst. After sonication, it is placed in an oven and reacted at a constant temperature for a period of time to carry out a micro-excess re-impregnation process.

[0009] (4) The catalyst obtained in step (3) is dried to obtain the reactivated hydrocracking catalyst.

[0010] In the above method, the calcination temperature in step (1) is 450-650℃ and the calcination time is 4-8h;

[0011] In the above method, the saturated water absorption in step (2) is determined by the following method: a certain amount of calcined catalyst particles are placed in a beaker and soaked in excess deionized water for 24 hours, and finally filtered and the wet weight of the catalyst particles is measured.

[0012] In the above method, in step (2), a certain amount of inorganic acid, organic acid and organic ligand are weighed and dissolved in deionized water, and stirred evenly at 20-60℃ for 0.5-1h to obtain a mixed solution; the total volume of the mixed solution is equal to or slightly greater than the saturated water absorption of the calcined catalyst particles.

[0013] In the above method, in the mixed solution described in step (2), the concentrations of organic acid and organic ligand are the same, and the molar concentration ratio of inorganic acid, organic acid and organic ligand is 1:(10-20):(10-20); preferably, the concentration of inorganic acid is (0.05-0.2) mol / L, the concentration of organic acid is (0.5-2) mol / L, and the concentration of organic ligand is (0.5-2) mol / L; more preferably, the concentration of inorganic acid is (0.05-0.12) mol / L, the concentration of organic acid is (1.0-1.2) mol / L, and the concentration of organic ligand is (1.0-1.2) mol / L.

[0014] In the above method, the inorganic acid in step (2) is one or more of nitric acid, phosphoric acid, and hydrochloric acid; preferably nitric acid.

[0015] In the above method, the organic acid mentioned in step (2) is one or more of citric acid, malic acid, oxalic acid, tartaric acid, mercaptoacetic acid, and maleic acid; preferably citric acid and / or malic acid;

[0016] In the above method, the organic ligand in step (2) is one or more of lysine, glutamic acid, arginine, glycine, ethylene glycol, glycerol, ethanolamine, and ethylenediamine; preferably ethylene glycol and glycerol.

[0017] In the above method, the ultrasonic treatment time in step (3) is 5-60 min, the oven temperature is 20-80℃, and the reaction time is 6-12 h;

[0018] In the above method, the drying temperature in step (4) is 90-110℃ and the drying time is 6-12h.

[0019] The present invention also provides a hydrocracking catalyst product prepared by the above method.

[0020] This invention dissolves the metal components and inert metal species Al2(MoO4)3 and β-NiMoO4 accumulated on the surface of hydrocracking waste catalyst by adding inorganic and organic acids. The organic ligands added in this invention are multidentate organic ligands. The multidentate organic ligands and organic acids in the mixed solution coordinate with the dissolved active metal to form metal-organic complexes. The hydroxyl, carboxyl, and amino groups in the organic acids and organic ligands form a "hydrogen bond network" with the metal to encapsulate the metal species and form five- or six-membered cyclic metal-organic complexes. This allows the metal to be redispersed in the catalyst channels and on the surface, and the active metal is re-impregnated, thus improving the dispersion of the metal on the support surface.

[0021] This invention controls the volume and concentration of the mixed solution of inorganic acid, organic acid, and organic ligands by measuring the saturated water absorption of the calcined catalyst. The re-impregnation process is carried out in a slightly excess solution, eliminating the need for filtration and avoiding metal loss during drying. The slightly excess re-impregnation involves completely wetting the catalyst with a solution containing metal components dissolved from the spent catalyst until a liquid film covers the catalyst surface. This utilizes capillary action to allow the active metal-organic complex to diffuse uniformly on the catalyst's outer surface and within its pores, ultimately achieving redispersibility of the active metal. Insufficient solution volume prevents the active metal from diffusing to all parts of the catalyst, resulting in uneven dispersion; while excessive solution leads to residual active components on the vessel walls during drying, causing metal loss.

[0022] In this invention, the concentration range of inorganic acid and organic acid in the mixed solution is controlled. If the concentration of inorganic acid is too high, it may affect the ionization equilibrium of organic acid, causing the equilibrium to shift to the left, resulting in a decrease in the degree of ionization of organic acid ions. If the concentration of organic acid and inorganic acid is too low, it will be difficult to completely dissolve the metal. If the concentration is too high, it will cause the catalyst skeleton structure to collapse and be destroyed.

[0023] After the re-impregnation treatment, the active metal and organic ligands are finally loaded onto the catalyst in a complex state. Traditional methods for recycling spent catalysts typically involve slurry treatment with excess acid or alkali solutions, resulting in most of the metal being loaded on the outer surface. However, the method of this invention allows the active metal in the catalyst to settle within the pores, eliminating the need for calcination and avoiding the aggregation and growth of metal during calcination. During the high-temperature pre-sulfurization stage before the hydrocracking reaction, the organic ligands decompose under a high-temperature hydrogen atmosphere to generate residual carbon, which coats the metal surface and acts as a buffer against the active phase, preventing the active metal from agglomerating and growing at high temperatures. Simultaneously, the formation of the metal-active organic ligand can alter the degree of sulfidation and the sulfidation temperature of the active metal in the hydrocracking catalyst, thereby changing the number of stacking layers of the active phase. This results in the generation of more short-stacked, highly dispersed, and highly active NiMoS active phases, increasing the degree of sulfidation and ultimately improving the hydrocracking performance of the catalyst.

[0024] Furthermore, inorganic and organic acids, in addition to dissolving and agglomerating the metal components, also remove skeletal and non-skeletal aluminum from the catalyst, increasing the specific surface area and pore volume of the catalyst. Moreover, during the high-temperature sulfidation stage, the thermal decomposition of the metal-organic complex within the pores also plays a role in pore expansion, ultimately achieving the unblocking and reconstruction of the catalyst's pore structure.

[0025] Compared with existing technologies, this invention reactivates catalyst particles without damaging their original structure, eliminating the need for re-forming and the addition of carriers and metals. This improves resource utilization and provides a simple and efficient method for reactivating spent hydrocracking catalysts. Furthermore, it simplifies the process, significantly reduces energy consumption, effectively saves costs, and enables the sustainable utilization of waste resources. Attached Figure Description

[0026] Figure 1 XRD patterns of spent catalysts, catalysts obtained from the regeneration treatment of Examples 1-3 and Comparative Example 2.

[0027] Figure 2 The images show the UV characterization of the spent catalyst, the calcined catalyst, and the catalysts obtained from the reactivation treatment of Example 1 and Comparative Example 2.

[0028] Figure 3 This is a TEM image of the spent catalyst.

[0029] Figure 4 This is a TEM image of the catalyst obtained from the reactivation treatment in Example 1.

[0030] Figure 5 This is a TEM image of the catalyst obtained from the reactivation treatment in Example 2.

[0031] Figure 6 This is a TEM image of the catalyst obtained from the reactivation treatment in Example 3.

[0032] Figure 7 This is a TEM image of the catalyst obtained from the regeneration treatment in Comparative Example 2.

[0033] Figure 8 This is a TEM image of the catalyst obtained from the regeneration treatment in Comparative Example 2. Detailed Implementation

[0034] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the present invention in any way.

[0035] Example 1

[0036] (1) The spent hydrocracking catalyst particles were roasted at 600°C in air for 6 hours to remove carbon deposits.

[0037] (2) Take 20g of the calcined catalyst in a beaker, add an appropriate amount of deionized water and soak for 24h. After filtration, weigh the wet weight of the catalyst and determine the saturated water absorption of the catalyst (16mL). Weigh 0.1g of nitric acid, 3g of citric acid and 1g of ethylene glycol and dissolve them in 16mL of deionized water. Stir evenly at 60℃ for 0.5h to obtain a mixed solution with a nitric acid concentration of 0.1mol / L, a citric acid concentration of 1mol / L and an ethylene glycol concentration of 1mol / L.

[0038] (3) The mixed solution was added dropwise to the calcined catalyst until a uniform liquid film covered the surface of the catalyst; after mixing and sealing, it was ultrasonically treated at 60°C for 20 min; then it was placed in a 60°C oven and left to stand for 12 hours.

[0039] (4) Heat to 110℃ and dry for 4 hours to obtain the reactivated hydrocracking catalyst.

[0040] Example 2

[0041] (1) The spent hydrocracking catalyst particles were roasted at 600°C in air for 6 hours to remove carbon deposits.

[0042] (2) Take 20g of the calcined catalyst into a beaker, add an appropriate amount of deionized water and soak for 24h. After filtration, weigh the wet weight of the catalyst and determine the saturated water absorption of the catalyst (16mL). Weigh 0.1g of nitric acid, 2.1g of malic acid and 1g of ethylene glycol and dissolve them in 16mL of deionized water. Stir evenly at 60℃ for 0.5h to obtain a mixed solution with a nitric acid concentration of 0.1mol / L, a malic acid concentration of 1mol / L and an ethylene glycol concentration of 1mol / L.

[0043] (3) The mixed solution was added dropwise to the calcined catalyst until a uniform liquid film covered the surface of the catalyst; after mixing and sealing, it was ultrasonically treated at 60°C for 20 min; then it was placed in a 60°C oven and left to stand for 12 hours.

[0044] (4) Heat to 110℃ and dry for 4 hours to obtain the reactivated hydrocracking catalyst.

[0045] Example 3

[0046] The spent hydrocracking catalyst particles were calcined at 600℃ in air for 6 hours to remove carbon deposits. 20g of the calcined catalyst was placed in a beaker, soaked in an appropriate amount of deionized water for 24 hours, filtered, and the wet weight of the catalyst was weighed. The saturated water absorption of the catalyst (16mL) was determined. 0.1g of nitric acid, 3g of citric acid, and 2.33g of lysine were weighed and dissolved in 16mL of deionized water. The solution was stirred uniformly at 60℃ for 0.5 hours to obtain a mixed solution with a nitric acid concentration of 0.1mol / L, a citric acid concentration of 1mol / L, and a lysine concentration of 1mol / L. The mixed solution was added dropwise to the calcined catalyst until a uniform liquid film covered the catalyst surface. After mixing and sealing, the catalyst was ultrasonically treated at 60℃ for 20 minutes, then placed in a 60℃ oven and allowed to stand for 12 hours. After drying at 110℃ for 4 hours, the reactivated hydrocracking catalyst was obtained.

[0047] Comparative Example 1

[0048] The spent hydrocracking catalyst particles were calcined at 600℃ in air for 6 hours to remove carbon deposits. 10g of the calcined catalyst was placed in a beaker, and 0.2g of nitric acid, 6g of citric acid, and 2g of ethylene glycol were weighed and dissolved in 32mL of deionized water. The mixture was stirred uniformly at 60℃ for 0.5h to obtain a mixed solution with a nitric acid concentration of 0.1mol / L, a citric acid concentration of 1mol / L, and an ethylene glycol concentration of 1mol / L. The mixed solution was added dropwise to the calcined catalyst, with excess solution covering the catalyst. After mixing and sealing, the mixture was ultrasonically treated at 60℃ for 20min, then placed in a 60℃ oven and allowed to stand for 12 hours. After drying at 110℃ for 4h, the reactivated hydrocracking catalyst was obtained.

[0049] Comparative Example 2

[0050] The spent hydrocracking catalyst particles were calcined at 600℃ in air for 6 hours to remove carbon deposits. 20g of the calcined catalyst was placed in a beaker, soaked in an appropriate amount of deionized water for 24 hours, filtered, and the wet weight of the catalyst was weighed. The saturated water absorption of the catalyst (16mL) was determined. 0.1g of nitric acid and 3g of citric acid were weighed and dissolved in 16mL of deionized water. The mixture was stirred evenly at 60℃ for 0.5 hours to obtain a mixed solution with a nitric acid concentration of 0.1mol / L and a citric acid concentration of 1mol / L. The mixed solution was added dropwise to the calcined catalyst until a uniform liquid film covered the catalyst surface. After mixing and sealing, the mixture was ultrasonically treated at 60℃ for 20 minutes. Then, it was placed in a 60℃ oven and allowed to stand for 12 hours. After drying at 110℃ for 4 hours, the reactivated hydrocracking catalyst was obtained.

[0051] Test Example 1

[0052] XRD tests were performed on the spent hydrocracking catalyst, the catalyst samples obtained in Comparative Example 2, and Examples 1-3. The results are as follows: Figure 1 As shown in the figure, the XRD pattern of the spent catalyst showed small characteristic diffraction peaks of MoS2, NiS, and Ni3S2. These independently existing sulfides are low-activity metal active phases. The presence of characteristic diffraction peaks of the inert phase β-NiMoO4 indicates the presence of agglomeration and sintering of the metal active phase in the spent catalyst. The addition of organic and inorganic acids in Examples 1-3 and Comparative Example 2 caused the characteristic diffraction peaks of the metal active phase to disappear, indicating that the organic and inorganic acids dissolved the metal components aggregated on the catalyst surface. Furthermore, the disappearance of the characteristic diffraction peak of β-NiMoO4 in the catalyst samples of Examples 1-3 and Comparative Example 2 suggests that the addition of the inorganic acid-organic acid-organic ligand mixed solution transforms the inert species β-NiMoO4, redispersing the aggregated metal components and thus improving the dispersion of the active metal on the support.

[0053] Test Example 2

[0054] The spent catalyst, the calcined catalyst, and the catalyst samples obtained in Comparative Example 2 and Example 1 were subjected to ultraviolet characterization tests, and the results are as follows: Figure 2 As shown.

[0055] In the 230-280 nm range, molybdenum bonds are classified as tetrahedral (TD) coordination bonds, while in the 300-320 nm range, they are classified as octahedral (OT) coordination bonds. From Figure 2 As can be seen, the calcined catalyst exhibits characteristic peaks of tetrahedral coordinated molybdenum (β-NiMoO4) and octahedral coordinated molybdenum (MoO3). In contrast, the reactivated catalyst obtained in Example 1 shows a decrease in the content of tetrahedral coordinated molybdenum and an increase in the content of octahedral coordinated molybdenum. This indicates that the addition of organic ligands coordinates with the dissolved active metal to form octahedral coordinated metal-organic complexes. Compared to Example 1, the sample obtained in Comparative Example 2 shows a decrease in the area of ​​the characteristic peak of octahedral coordinated molybdenum. This is because no organic ligands were added during the reactivation process, resulting in the formation of fewer metal-organic complexes.

[0056] Test Example 3

[0057] Nitrogen physical adsorption-desorption tests were performed on fresh catalyst, spent catalyst, and catalyst samples obtained from Comparative Example 2 and Examples 1-3. The results are shown in Table 1.

[0058] Table 1. Pore structure properties of each sample

[0059] Waste catalyst 196 0.28 Comparative Example 2 224 0.33 Example 1 267 0.38 Example 2 251 0.37 Example 3 264 0.38

[0060] As can be seen from Table 1, compared with the spent catalyst and the catalyst of Comparative Example 2, the catalyst samples of Examples 1-3 all showed an increase in specific surface area and pore volume to varying degrees, indicating that the reactivation method provided by the present invention can achieve the expansion of the catalyst pore structure.

[0061] Test Example 4

[0062] ICP tests were performed on the fresh catalyst, the spent catalyst, Comparative Example 1, and the catalyst samples obtained in Examples 1-3. The results are shown in Table 2.

[0063] As can be seen from Table 2, the active metal components of the catalysts in Examples 1-3 revived by the method of the present invention remained basically unchanged during the revival process, while the catalyst revived using excess solution in Comparative Example 1 showed obvious loss of metal components.

[0064] Table 2 Elemental composition information of each sample

[0065] Fresh catalyst 6.6 22.4 Waste catalyst 5.9 21.1 Comparative Example 1 2.3 7.6 Example 1 5.4 20.6 Example 2 5.0 20.2 Example 3 5.2 20.3

[0066] Test Example 5

[0067] XPS tests were performed on the spent catalyst, Comparative Example 2, and catalyst samples obtained in Examples 1-3. The results are shown in Table 3.

[0068] Table 3 Valence state distribution of Mo and Ni active metals in each sample

[0069]

[0070] Mo is mainly used in catalysts in the form of Mo. 4+ Mo 5+ and Mo 6+ It exists in the form of Mo, where Mo 4+ It is mainly MoS2, which is the main active phase of hydrocracking catalyst. 5+ Mainly oxygen-containing molybdenum sulfide (MoS) x O y Mo 6+ It is mainly MoO3. Among them, Mo 4+ The content represents the degree of sulfidation of the catalyst. As can be seen from Table 3, the catalyst treated by the reactivation method of the present invention, after pre-sulfidation, has a higher degree of sulfidation than the spent catalyst and the catalyst of Comparative Example 2, and is close to that of the fresh catalyst. It also generates more NiMoS active phase and has higher hydrogenation activity.

[0071] Test Example 6

[0072] TEM tests were performed on the spent catalyst, the catalyst samples obtained in Comparative Example 2, and Examples 1-3. Figures 3-8 As shown in the figure, the results are shown in Table 4.

[0073] Table 4 Distribution of MoS2 stack length and number of stack layers

[0074] Number of stacking layers 2.6 4.9 3.7 2.8 3.0 3.4 Stacking length 3.1 5.4 4.7 3.3 3.7 4.0

[0075] For hydrocracking catalysts, when the hydrogenation metal active phase MoS2 has a shorter stack length and a larger number of stacked layers (approximately 3-4 layers), it possesses a greater number of active sites, and the catalyst generally exhibits higher hydrogenation activity. This is shown in Table 4. From the perspective of stack length, compared to spent catalysts, the catalyst revived in this invention has a shorter stack length and a larger number of stacked layers. The reduction in stack length also indicates good dispersion of the metal active phase, which is beneficial for the recovery of catalyst activity.

[0076] Application Example 1

[0077] The performance of the hydrocracking catalyst provided by the present invention was tested through the following application examples, and the evaluation results are shown in Table 5.

[0078] Using tetrahydronaphthalene as a feedstock, the spent catalyst, catalyst samples obtained in Examples 1-3 and Comparative Example 2 were evaluated for hydrocracking reaction in a fixed-bed hydrocracking reactor. The catalyst loading was 3 mL in all cases.

[0079] First, the catalyst is pre-sulfurized using a cyclohexane solution containing 2 wt% CS2.

[0080] Vulcanization conditions: temperature 320℃, pressure 4.0MPa, volume hourly space velocity 2h. -1 The hydrogen-to-oil volume ratio is 300:1, and the sulfidation time is 6 hours.

[0081] After sulfidation, the reaction raw material (a cyclohexane solution containing 20 wt% tetrahydronaphthalene) was pumped into a fixed-bed reactor, heated to the set temperature and stabilized for 4 hours, and then the sample was collected for offline analysis.

[0082] Hydrocracking reaction conditions: reaction temperature 360℃, reaction pressure 4.0MPa, volume hourly space velocity 2h. -1 The hydrogen-to-oil volume ratio was 300:1, and the reaction time was 2 hours.

[0083] The main reaction types of tetrahydronaphthalene on hydrocracking catalysts include isomerization, ring-opening, cracking, and dehydrogenation condensation. Therefore, based on the composition of its products, they can be classified as follows: ① Cracking products: mainly including C6-C9 alkylbenzenes and cycloalkanes such as benzene, toluene, and methylcyclohexane; ② Ring-opening products: mainly including C6-C9 alkylbenzenes and cycloalkanes such as benzene, toluene, and methylcyclohexane; 10 Alkylcycloalkanes and alkylbenzenes, such as butylbenzene and alkylcyclohexane; ③ Isomers: mainly including methyl indenium; ④ Hydrogenation products: mainly including decahydronaphthalene; ⑤ Dehydrocondensation products: mainly including naphthalene, alkylnaphthalene, alkyltetrahydronaphthalene, and aromatics with more than 10 carbon atoms. Calculate the conversion rate X of tetrahydronaphthalene. 四氢萘 Selectivity of various types of products S 裂化 S 开环 S 异构 S 加氢S 缩合 The calculation formula is as follows:

[0084]

[0085]

[0086] Table 5 Evaluation results of the catalyst

[0087] Waste catalyst 19.1 10.1 28.2 2.4 49.1 10.2 Fresh catalyst 90.6 23.4 56.2 5.8 8.6 6.0 Comparative Example 2 50.9 16.2 43.9 5.3 12.3 22.3 Example 1 85.4 21.2 55.3 5.4 9.2 8.9 Example 2 83.0 20.8 55.0 6.3 9.2 8.7 Example 3 79.8 18.8 56.2 6.7 9.8 8.5

[0088] As shown in Table 5, compared with the spent catalyst and Comparative Example 2, the catalysts obtained in Examples 1-3 all showed significantly improved conversion rates. The revived hydrocracking catalysts exhibited higher selectivity for cracking, ring-opening, and isomer products than the spent catalysts, indicating that the acidity of the revived catalysts was enhanced. This demonstrates that the revival method provided by this invention significantly improves the hydrocracking performance of spent hydrocracking catalysts, bringing them close to the catalytic activity of fresh catalysts.

Claims

1. A method for reactivating spent hydrocracking catalyst, characterized in that, It consists of the following steps: (1) The spent hydrocracking catalyst particles are roasted in air atmosphere to remove carbon deposits; (2) Measure the saturated water absorption of the catalyst after calcination, and prepare a mixed solution of inorganic acid, organic acid and organic ligand according to the saturated water absorption; weigh a certain amount of inorganic acid, organic acid and organic ligand respectively and dissolve them in deionized water, and stir evenly at 20-60℃ for 0.5-1h to obtain a mixed solution; the total volume of the mixed solution is equal to or slightly greater than the measured saturated water absorption of the calcined catalyst particles; in the mixed solution, the molar concentration ratio of inorganic acid, organic acid and organic ligand is 1:(10-20):(10-20), and the concentrations of organic acid and organic ligand are the same; the inorganic acid is one or more of nitric acid, phosphoric acid and hydrochloric acid; the organic acid is one or more of citric acid, malic acid, oxalic acid, tartaric acid, mercaptoacetic acid and maleic acid; the organic ligand is one or more of lysine, glutamic acid, arginine, glycine, ethylene glycol, glycerol, ethanolamine and ethylenediamine. (3) The mixed solution is added dropwise to the calcined catalyst obtained in step (1) until a uniform liquid film is covered on the surface of the catalyst. After sonication, it is placed in an oven and reacted at a constant temperature for a period of time to carry out a micro-excess re-impregnation process. (4) The catalyst obtained in step (3) is dried to obtain the reactivated hydrocracking catalyst.

2. The method for reactivating spent hydrocracking catalyst according to claim 1, characterized in that, In step (1), the roasting temperature is 450-650 ℃ and the roasting time is 4-8h; The saturated water absorption in step (2) is determined by the following method: a certain amount of calcined catalyst particles are placed in a beaker and soaked in excess deionized water for 24 hours. Finally, the particles are filtered and the wet weight of the catalyst particles is weighed to determine the absorption.

3. The method for reactivating spent hydrocracking catalyst according to claim 1, characterized in that, The concentration of inorganic acid is (0.05-0.2) mol / L, the concentration of organic acid is (0.5-2) mol / L, and the concentration of organic ligand is (0.5-2) mol / L.

4. The method for reactivating spent hydrocracking catalyst according to claim 3, characterized in that, The concentration of inorganic acid is (0.05-0.12) mol / L, the concentration of organic acid is (1.0-1.2) mol / L, and the concentration of organic ligand is (1.0-1.2) mol / L.

5. The method for reactivating spent hydrocracking catalyst according to claim 1, characterized in that, The inorganic acid is nitric acid; the organic acid is citric acid and / or malic acid; and the organic ligand is ethylene glycol and / or glycerol.

6. The method for reactivating spent hydrocracking catalyst according to claim 1, characterized in that, The ultrasonic treatment time in step (3) is 5-60 min, the oven temperature is 20-80℃, and the reaction time is 6-12 h.

7. The method for reactivating spent hydrocracking catalyst according to claim 1, characterized in that, The drying temperature in step (4) is 90-110℃ and the drying time is 6-12h.

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