An in-situ construction of an atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment, its preparation method and application

Abstract

This invention relates to the field of petroleum refining, and discloses an in-situ construction of an atomically dispersed molybdenum catalytic system in a heavy oil slurry-bed hydrotreating environment, its preparation method, and its application. This invention uses asphalt as a precursor, N and S sources containing heteroatoms as chelating ligand molecules, and a soft template agent as a pore-forming agent. During the self-assembly process, metallic molybdenum salt is added in situ, simultaneously achieving targeted anchoring of the ligand molecules to molybdenum sites and their stable dispersion on the asphalt. Finally, an atomically dispersed molybdenum catalytic system is constructed by in-situ sulfidation in a heavy oil slurry-bed hydrotreating environment. This catalytic system exhibits high metal dispersion, requires no subsequent processing, produces high-purity products, has no loss of active metal components, and high atomic utilization. It demonstrates excellent catalytic activity, stability, and coking ability in heavy oil hydrotreating, and can efficiently process low-quality heavy oil with high residual carbon, high metal content, and high sulfur content. The operation is simple and controllable, with good raw material applicability and low production cost, making it valuable for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of petroleum refining, specifically to an in-situ constructed atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment, its preparation method, and its application. Background Technology

[0002] With the gradual depletion of global oil reserves and their increasing heavy and inferior quality, converting heavy oil into light oil products or chemical feedstocks through advanced technologies is a significant challenge for the green and sustainable development of the refining industry. Compared to traditional fixed-bed and moving-bed technologies, slurry-bed hydrotreating technology utilizes a tubular empty reactor, where a small amount of dispersed catalyst, along with heavy oil and hydrogen, flows upwards through the reactor, thereby achieving the lightification of inferior heavy oil. Heavy oil slurry-bed hydrotreating technology can not only efficiently process inferior heavy oil with high residual carbon, high metal content, and high sulfur content, but also effectively reduce the amount of coke produced during the reaction process. It features strong feedstock adaptability, simple process, high conversion rate, and high light oil yield, making it an effective technical means to achieve the lightification of inferior heavy oil and possessing promising industrial application prospects.

[0003] Hydrogenation catalysts play a crucial role in heavy oil slurry-bed hydrogenation reaction systems. During the reaction...

[0004] In this process, the catalyst activates hydrogen molecules to form active hydrogen, which reacts with free radical intermediates from the thermal cracking of heavy oil macromolecules. This inhibits the condensation reaction of free radicals, thereby suppressing coke formation and completing the heavy oil lightening process. The catalyst then exits the process or enters the tail oil during subsequent separation. A low-cost catalyst system with high conversion frequency and high atom utilization can promote hydrogen activation and hydrogen transfer reactions, thereby enabling hydrogen free radicals to rapidly quench the free radicals of heavy oil macromolecules, achieving the goal of heavy oil lightening and inhibiting coking, and avoiding equipment wear and blockage caused by scaling and coking. However, current heavy oil hydrotreating catalysts suffer from technical problems such as easy agglomeration and deactivation, low metal atom utilization, and easy coking, which seriously affect the large-scale promotion of slurry bed hydrotreating technology for converting inferior heavy oil. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an in-situ constructed atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrogenation, its preparation, and its application. The technical solution is as follows:

[0006] An in-situ atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrogenation is disclosed, comprising a precursor, an active metal component, heteroatom ligands, and a soft template agent. The precursor is asphalt. The active metal component is molybdenum, which is highly dispersed in the form of single atoms or atomic clusters on a porous carbon support. The heteroatom ligands include N-ligands and S-ligands. The mass fractions of the active metal molybdenum are 1 wt.% to 10 wt.%, the mass fractions of the N-ligands are 1 wt.% to 8 wt.%, the mass fractions of the S-ligands are 1 wt.% to 8 wt.%, and the mass fraction of the soft template agent is 10 wt.% to 20 wt.%.

[0007] Furthermore, the asphalt is one or more of coal tar pitch, petroleum asphalt, and mesophase asphalt; the source compound of the active metal molybdenum is one or more of ammonium molybdate tetrahydrate, molybdenum acetylacetonate, molybdenum pentachloride, and molybdenum hexacarbonyl; the source of the N ligand is one or more of melamine, ammonia, dicyandiamine, hydroxylamine chloride, and ethanolamine; the source of the S ligand is one or more of trithiocyanate, sulfur powder, dibenzyl disulfide, thiourea, and thioacetamide; and the soft template agent is one or more of Urea, CTAC, CTAB, g-C3N4, ZnO, PVA, PVP, P123, and P127.

[0008] The preparation method of an in-situ atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment, as described above, includes the following steps:

[0009] (1) The asphalt and N ligand source were uniformly dispersed in anhydrous ethanol to obtain mixed solution I;

[0010] (2) After mixing the soft template agent with deionized water, add it to the mixed solution I obtained in step (1) which is currently being stirred to obtain mixed solution II;

[0011] (3) Dissolve the molybdenum source compound in deionized water and add it dropwise to the mixed solution II obtained in step (2) which is currently being stirred, to obtain mixed solution III;

[0012] (4) Add the S ligand source to the mixed solution III obtained in step (3) to obtain mixed solution IV, and continue to stir mixed solution IV to ensure that the reaction is complete;

[0013] (5) Dry the fully reacted mixture IV from step (4) to obtain the catalyst precursor;

[0014] (6) The catalyst precursor obtained in step (5) is pre-dispersed in FCC diesel oil and then fully mixed and dispersed in a high-pressure reactor with vacuum residue.

[0015] (7) After the autoclave is heated to a certain temperature, in-situ sulfidation occurs to obtain an atomically dispersed molybdenum catalytic system.

[0016] Furthermore, the mass ratio of asphalt, N-ligand source, soft template agent, molybdenum source compound, and S-ligand source added in steps (1), (2), (3), and (4) is (5-20):(5-20):(5-20):(1-4):(2.5-10).

[0017] Furthermore, in step (4), stirring is carried out at room temperature for 24 hours to ensure complete reaction; in step (5), the drying temperature is 70-100℃ and the drying time is 12-36 hours; in step (7), the in-situ sulfidation temperature is 200-300℃.

[0018] Furthermore, ultrasonic treatment is used in step (1) when asphalt, N-ligand source and anhydrous ethanol are mixed, in step (2) when soft template agent and deionized water are mixed and in step (3) when molybdenum source compound and deionized water are mixed.

[0019] The application of an in-situ atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrogenation, obtained based on the above preparation method, includes the following steps:

[0020] (1) The catalyst precursor is pre-dispersed into FCC diesel oil and then thoroughly mixed with vacuum residue and placed into a high-pressure reactor;

[0021] (2) Purge the autoclave with hydrogen to remove the air inside, then pressurize it to the initial reaction pressure and use a hazardous gas detector to check the airtightness of the device;

[0022] (3) Start the autoclave, stir the contents of the autoclave thoroughly, and start the reaction after the reaction temperature is reached;

[0023] (4) After the reaction is complete, wait for the autoclave to cool to room temperature, then take out the product from the autoclave for oil analysis.

[0024] Furthermore, in step (1), the mass ratio of molybdenum in the catalyst precursor to vacuum residue is 100–500 μg / g.

[0025] Furthermore, the initial reaction pressure in step (2) is 6-10 MPa.

[0026] Furthermore, the reaction temperature in step (3) is 400-440℃ and the reaction time is 1h.

[0027] Compared with existing heavy oil slurry bed hydrogenation catalytic systems, this invention has the following significant advantages:

[0028] 1. This invention uses asphalt as a precursor, N and S sources containing heteroatoms as chelating ligand molecules, and a soft template agent as a pore-forming agent. During the self-assembly process, molybdenum salt is added in situ, simultaneously achieving targeted anchoring of the ligand molecules to molybdenum sites and their stable dispersion on the asphalt. Finally, an atomically dispersed molybdenum catalytic system is constructed through in-situ sulfidation in a heavy oil slurry bed hydrogenation environment. This catalytic system exhibits high metal dispersion, requires no subsequent processing, produces high-purity products, has no loss of active metal components, and boasts high atom utilization.

[0029] 2. The atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrotreating prepared by this invention exhibits excellent catalytic activity, stability, and coking suppression ability for heavy oil hydrotreating. It can effectively and efficiently process low-quality heavy oil with high residual carbon, high metal content, and high sulfur content, while effectively reducing the amount of coke generated during the reaction process.

[0030] 3. The heavy oil slurry bed hydrogenation in-situ atomically dispersed molybdenum catalytic system prepared by this invention is simple and controllable to operate, has good raw material applicability, low production cost, and has good industrial application value. Detailed Implementation

[0031] The following specific embodiments further illustrate the catalytic performance of the in-situ constructed atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrocracking environment for the hydrocracking reaction of vacuum residue. It should be noted that the following embodiments are merely exemplary, and the scope of protection of this invention is not limited to these embodiments. Example 1

[0032] Weigh 1g of coal tar pitch and 1g of melamine and disperse them in 100mL of anhydrous ethanol. After ultrasonic treatment, a mixed solution is obtained and stirred on a stirring table. Weigh 1g of soft template agent Urea and dissolve it in 50mL of deionized water. Add it to the above solution to obtain a mixed solution. Weigh 200mg of ammonium molybdate tetrahydrate and dissolve it in 50mL of deionized water. Add the completely dissolved molybdenum salt solution dropwise to the above mixed solution. Then add 0.5g of thiocyanate and stir at room temperature for 24h. Place the above stirred mixed solution in a forced-air drying oven and dry it at 80℃ for 24h. Then transfer it to a mortar and grind it thoroughly to obtain the catalyst precursor.

[0033] The precursor was dispersed in FCC diesel (i.e., diesel obtained by catalytic cracking) at an active metal input of 450 μg / g, and then thoroughly mixed with 100g of Qingdao Refining & Chemical vacuum residue and poured into a high-pressure reactor. After sulfidation, an atomically dispersed molybdenum catalytic system A1 was obtained. The airtightness of the device was checked, and the pressure was increased to the initial reaction pressure of 7 MPa. After the reaction temperature reached 425℃, the reaction was carried out for 1 hour. After the reaction was completed, the temperature was lowered to room temperature, and the oil in the reactor was taken out for oil analysis. Example 2

[0034] Referring to Example 1, the added soft template agent was CTAC, and the resulting atomically dispersed molybdenum catalytic system was A2. Example 3

[0035] Referring to Example 1, the added soft template agent was CTAB, and the resulting atomically dispersed molybdenum catalytic system was A3. Example 4

[0036] Referring to Example 1, the added soft template agent was g-C3N4, and the resulting atomically dispersed molybdenum catalytic system was A4. Example 5

[0037] Referring to Example 1, the added soft template agent was ZnO, and the resulting atomically dispersed molybdenum catalytic system was A5. Example 6

[0038] Referring to Example 1, the added soft template agent was PVA, and the resulting atomically dispersed molybdenum catalytic system was A6. Example 7

[0039] Referring to Example 1, the added soft template agent was PVP, and the resulting atomically dispersed molybdenum catalytic system was A7. Example 8

[0040] Referring to Example 1, the added soft template agent was P123, and the resulting atomically dispersed molybdenum catalytic system was A8. Example 9

[0041] Referring to Example 1, the added soft template agent was F127, and the resulting atomically dispersed molybdenum catalytic system was A9.

[0042] Comparative Example 1

[0043] Weigh 1g of coal tar pitch and 1g of melamine and disperse them in 100mL of anhydrous ethanol. After ultrasonic treatment, a mixed solution is obtained and placed on a stirring table for stirring. Weigh 200mg of ammonium molybdate tetrahydrate and dissolve it in 50mL of deionized water. Add the completely dissolved molybdenum salt solution dropwise to the above mixed solution, then add 0.5g of thiocyanate and stir at room temperature for 24h. Place the above mixed solution in a forced-air drying oven and dry it at 80℃ for 24h. Then transfer it to a mortar and grind it thoroughly to obtain the catalyst precursor.

[0044] The precursor was dispersed in FCC diesel (i.e., diesel obtained by catalytic cracking) at an active metal input of 450 μg / g, and then thoroughly mixed with 100g of Qingdao Refining & Chemical vacuum residue and poured into a high-pressure reactor. After sulfidation, atomically dispersed molybdenum catalytic system B1 was obtained. The airtightness of the device was checked, and the pressure was increased to the initial reaction pressure of 7 MPa. After the reaction temperature reached 425℃, the reaction was carried out for 1 hour. After the reaction was completed, the temperature was lowered to room temperature, and the oil in the reactor was taken out for oil analysis.

[0045] Comparative Example 2

[0046] The hydrotreating performance of 100g of Qingdao Refining & Chemical vacuum residue without the addition of a catalyst was evaluated and denoted as B2.

[0047] The raw materials used in the above examples and comparative examples for evaluating the hydrotreating performance were all vacuum residue from Qingdao Refining & Chemical Co., Ltd. (properties shown in Table 1). All reactions were carried out under the same conditions: an initial hydrogen pressure of 7 MPa, a reaction temperature of 425°C, and a reaction time of 1 h. The precursor content, calculated as metallic molybdenum, ranged from 100 to 500 μg / g. Table 2 shows the hydrotreating evaluation results of heavy oil in Examples 1-9 and Comparative Examples 1-2.

[0048] Table 1 Properties of vacuum residue from Qingdao Refining & Chemical Co., Ltd.

[0049]

[0050] Table 2 Evaluation results of heavy oil hydrotreating in Examples 1-9 and Comparative Examples 1-2

[0051]

[0052] Table 2 shows that the in-situ atomically dispersed molybdenum catalytic system prepared by this invention in a heavy oil slurry bed hydrogenation environment all exhibit certain catalytic activity and coking suppression performance. In Comparative Example 2 without catalyst, the coking amount was as high as 9.46 wt.%, and the gas content was as high as 10.93 wt.%. In Comparative Example 1, the coking amount was reduced to 1.68 wt.%, and the gas content was reduced to 7.36 wt.%, already showing good catalytic activity and coking suppression performance. In Example 4, using g-C3N4 as a soft template agent, the coking amount was further reduced to 0.75 wt.%, and the gas content was further reduced to 7.14 wt.%, indicating that this template agent makes the metallic Mo more uniformly and stably dispersed on the pitch carbon material, resulting in the best catalytic effect. However, when other template agents were added, the coking amount increased, even exceeding that of Comparative Example 1. Of course, an error within 0.5% is normal and will not be explained further. In summary, the in-situ atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrogenation prepared in this invention exhibits excellent heavy oil hydrogenation performance, significantly reduces the generation of byproducts such as coke and gas, and promotes the efficient conversion of heavy oil.

Claims

1. A method for preparing an atomically dispersed molybdenum catalytic system in situ in a heavy oil slurry bed hydrogenation environment, characterized in that, The following steps are involved: (1) The asphalt and N ligand source were uniformly dispersed in anhydrous ethanol to obtain mixed solution I; (2) After mixing the soft template agent with deionized water, add it to the mixed solution I obtained in step (1) which is currently being stirred to obtain mixed solution II; (3) Dissolve the molybdenum source compound in deionized water and add it dropwise to the mixed solution II obtained in step (2) which is currently being stirred, to obtain mixed solution III; (4) Add the S ligand source to the mixed solution III obtained in step (3) to obtain mixed solution IV, and continue to stir mixed solution IV to ensure that the reaction is complete; (5) Dry the fully reacted mixture IV from step (4) to obtain the catalyst precursor; (6) The catalyst precursor obtained in step (5) is pre-dispersed in FCC diesel oil and then fully mixed and dispersed in a high-pressure reactor with vacuum residue. (7) After the autoclave is heated to 200-300℃, in-situ sulfidation occurs to obtain an atomically dispersed molybdenum catalytic system; The in-situ atomically dispersed molybdenum catalytic system constructed in the heavy oil slurry bed hydrogenation environment includes a precursor, an active metal component, a heteroatom ligand, and a soft template agent; the precursor is asphalt. The active metal component is molybdenum, which is highly dispersed on a porous carbon support in the form of single atoms or atomic clusters; the heteroatom ligands include N ligands and S ligands; wherein: the mass fraction of the active metal molybdenum is 1 wt.% to 10 wt.%, the mass fraction of the N ligand is 1 wt.% to 8 wt.%, the mass fraction of the S ligand is 1 wt.% to 8 wt.%, and the mass fraction of the soft template agent is 10 wt.% to 20 wt.%. The soft template agent is one or more of Urea, CTAC, CTAB, g-C3N4, ZnO, PVA, PVP, P123, and P127.

2. The method for preparing an in-situ atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment according to claim 1, characterized in that, The asphalt is one or more of coal tar pitch, petroleum asphalt, and mesophase asphalt; the source compound of the active metal molybdenum is one or more of ammonium molybdate tetrahydrate, molybdenum acetylacetonate, molybdenum pentachloride, and molybdenum hexacarbonyl; the source of the N ligand is one or more of melamine, ammonia, dicyandiamine, hydroxylamine chloride, and ethanolamine; and the source of the S ligand is one or more of trithiocyanic acid, sulfur powder, dibenzyl disulfide, thiourea, and thioacetamide.

3. The method for preparing an in-situ atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment according to claim 1, characterized in that, The mass ratio of asphalt, N-ligand source, soft template agent, molybdenum source compound, and S-ligand source added in steps (1), (2), (3), and (4) is (5-20):(5-20):(5-20):(1-4):(2.5-10).

4. The method for preparing an in-situ atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment according to claim 1, characterized in that, In step (4), stirring is carried out at room temperature for 24 hours to ensure complete reaction; in step (5), the drying temperature is 70-100℃ and the drying time is 12-36 hours.

5. The method for preparing an in-situ atomically dispersed molybdenum catalytic system in a heavy oil slurry bed hydrogenation environment according to claim 1, characterized in that, Ultrasonic treatment is used in all three steps: (1) mixing asphalt, N-ligand source and anhydrous ethanol; (2) mixing soft template agent and deionized water; and (3) mixing molybdenum source compound and deionized water.

6. The application of an in-situ atomically dispersed molybdenum catalytic system for heavy oil slurry bed hydrogenation, obtained by the preparation method according to any one of claims 1-5, in slurry bed heavy oil hydrogenation, characterized in that... The following steps are involved: ① The catalyst precursor is pre-dispersed in FCC diesel oil and then thoroughly mixed with vacuum residue and placed in a high-pressure reactor; ②Purge the autoclave with hydrogen to remove the air inside, then pressurize it to the initial reaction pressure and use a hazardous gas detector to check the airtightness of the device; ③ Start the autoclave, stir the substances inside the autoclave thoroughly, and begin the reaction after reaching the reaction temperature; ④ After the reaction is complete and the autoclave has cooled to room temperature, remove the product from the autoclave for oil analysis.

7. The application of the in-situ construction of an atomically dispersed molybdenum catalytic system in a slurry bed hydrogenation environment according to claim 6 in slurry bed heavy oil hydrogenation, characterized in that, In step ①, the mass ratio of molybdenum to vacuum residue in the catalyst precursor is 100–500 μg / g.

8. The application of the in-situ construction of an atomically dispersed molybdenum catalytic system in a slurry bed hydrogenation environment according to claim 6 in slurry bed heavy oil hydrogenation, characterized in that, The initial reaction pressure in step ② is 6–10 MPa.

9. The application of the in-situ construction of an atomically dispersed molybdenum catalytic system in a slurry bed hydrogenation environment according to claim 6 in slurry bed heavy oil hydrogenation, characterized in that, The reaction temperature in step ③ is 400-440℃, and the reaction time is 1 hour.

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