Atomic-scale dispersed molybdenum catalytic system constructed in situ in heavy oil slurry reactor hydrogenation environment and preparation method and application thereof

Abstract

The invention relates to the field of petroleum refining, and discloses a heavy oil slurry bed hydrogenation environment in-situ construction atomic-scale dispersed molybdenum catalytic system and a preparation method and application thereof. According to the preparation method, asphalt is taken as a precursor, an N source and an S source containing heteroatoms are taken as chelating ligand molecules, a soft template agent is taken as a pore-forming agent, and metal molybdenum salt is added in situ in a self-assembly process, so that targeted anchoring of the ligand molecules to molybdenum sites and stable dispersion of the ligand molecules on the asphalt are synchronously realized; and finally, carrying out in-situ vulcanization in a heavy oil slurry bed hydrogenation environment to construct an atomic-scale dispersed molybdenum catalytic system. The catalytic system has the advantages of high metal dispersity, no subsequent treatment process, high product purity, no loss of metal active components and high atom utilization rate; the catalyst shows excellent heavy oil hydrogenation catalytic activity, stability and coke inhibition capability, and can efficiently treat inferior heavy oil with high carbon residue, high metal and high sulfur; the method is simple and controllable in operation, good in raw material applicability, low in production cost and good in industrial application value.

Description

Technical Field

[0001] The present invention relates to the field of petroleum refining, and in particular to an atomic-level dispersed molybdenum catalytic system constructed in situ in a heavy oil slurry bed hydrogenation environment, and a preparation method and application thereof. Background Art

[0002] As global oil reserves gradually decrease and become heavier and inferior, how to convert heavy oil into light oil or chemical raw materials through advanced technology is one of the important challenges facing the green and sustainable development of the refining industry. Compared with traditional fixed bed and moving bed technologies, slurry bed hydrogenation technology uses a tubular hollow cylinder reactor to pass a small amount of dispersed catalyst together with heavy oil and hydrogen from bottom to top through the reactor, thereby achieving the lightness of inferior heavy oil. Heavy oil slurry bed hydrogenation technology can not only efficiently process inferior heavy oil with high residual carbon, high metal and high sulfur, but also effectively reduce the amount of coke produced during the reaction process. It has the characteristics of strong raw material adaptability, simple process, high conversion rate, and high light oil yield. It is an effective technical means to achieve the lightness of inferior heavy oil and has good industrial application prospects.

[0003] Hydrogenation catalyst plays a vital role in the heavy oil slurry bed hydrogenation reaction system. During the process, the catalyst can activate hydrogen molecules to form active hydrogen, and react with free radical intermediates after thermal cracking of heavy oil macromolecules, inhibit the condensation reaction of free radicals and thus inhibit the formation of coke, complete the heavy oil lightening process, and exit or enter the tail oil with the subsequent separation process. A low-cost catalyst system with high conversion frequency and high atomic utilization can promote the hydrogen activation and hydrogen transfer reactions, and then make the hydrogen free radicals quickly quench the heavy oil macromolecule free radicals, so as to achieve the purpose of lightening heavy oil and inhibiting coke formation, and avoid equipment wear and blockage caused by scaling and coking. However, the existing heavy oil hydrogenation catalysts have technical problems such as easy agglomeration and deactivation, low metal atom utilization, and easy coking of the system during the reaction process, which seriously affect the large-scale promotion of slurry bed hydrogenation conversion of inferior heavy oil technology. Summary of the invention

[0004] In view of the above technical problems, the present invention provides an atomic-level dispersed molybdenum catalyst system constructed in situ in a heavy oil slurry bed hydrogenation environment and its preparation and application, and its technical solution is as follows: An atomic-level dispersed molybdenum catalytic system is constructed in situ in a heavy oil slurry bed hydrogenation environment, comprising a precursor, an active metal component, a heteroatom ligand and a soft template; the precursor is asphalt; the active metal component is molybdenum, which is highly dispersed on a porous carbon carrier in the form of single atoms or atomic clusters; the heteroatom ligands include N ligands and S ligands; wherein: the mass fraction of active metal molybdenum is 1wt.%~10wt.%, the mass fraction of N ligands is 1wt.%~8wt.%, the mass fraction of S ligands is 1wt.%~8wt.%, and the mass fraction of soft template is 10wt.%~20wt.%.

[0005] Furthermore, the asphalt is one or more of coal tar, 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 hexacarbonyl molybdenum; the source of the N ligand is one or more of melamine, ammonia water, dicyandiamide, hydroxylamine chloride, and ethanolamine; the source of the S ligand is one or more of thiocyanuric acid, sulfur powder, dibenzyl disulfide, thiourea, and thioacetamide; the soft template is one or more of Urea, CTAC, CTAB, g-C3N4, ZnO, PVA, PVP, P123, and P127.

[0006] According to the above-mentioned preparation method of in-situ construction of atomic-level dispersed molybdenum catalyst system in heavy oil slurry bed hydrogenation environment, it comprises the following steps: (1) Evenly dispersing asphalt and N ligand source in anhydrous ethanol to obtain a mixed solution I; (2) mixing the soft template with deionized water and adding the mixture to the mixed solution I obtained in step (1) which is in a stirring state, to obtain a mixed solution II; (3) dissolving the molybdenum source compound in deionized water and adding the solution dropwise to the mixed solution II obtained in step (2) which is in a stirring state to obtain a mixed solution III; (4) adding the S ligand source to the mixed solution III obtained in step (3) to obtain a mixed solution IV, and continuing to stir the mixed solution IV to ensure that the reaction is complete; (5) drying the mixed solution IV after sufficient reaction in step (4) to obtain a catalyst precursor; (6) pre-dispersing the catalyst precursor obtained in step (5) in FCC diesel, and then fully mixing it with vacuum residue oil and dispersing it in an autoclave; (7) The autoclave is heated to a certain temperature and in-situ sulfurization is carried out to obtain an atomically dispersed molybdenum catalytic system.

[0007] Furthermore, the mass ratio of the asphalt, N ligand source, soft template, molybdenum source compound and S ligand source added in steps (1), (2), (3) and (4) is (5-20): (5-20): (1-4): (2.5-10).

[0008] Furthermore, the stirring in step (4) is carried out at room temperature for 24 hours to ensure that the reaction is complete; the drying temperature in step (5) is 70 to 100° C. and the drying time is 12 to 36 hours; and the certain temperature for in-situ vulcanization in step (7) is 200 to 300° C.

[0009] Furthermore, in step (1), when the asphalt, the N ligand source and the anhydrous ethanol are mixed, in step (2), when the soft template agent and the deionized water are mixed, and in step (3), when the molybdenum source compound and the deionized water are mixed, ultrasonic treatment is adopted.

[0010] The application of an atomically dispersed molybdenum catalyst system in situ constructed in a heavy oil slurry bed hydrogenation environment obtained based on the above-mentioned preparation method in slurry bed heavy oil hydrogenation comprises the following steps: (1) Pre-dispersing the catalyst precursor into FCC diesel, then fully mixing it with vacuum residue and placing it into an autoclave; (2) Purge the autoclave with hydrogen, exhaust the air in the autoclave, pressurize it to the initial reaction pressure, and use a hazardous gas detector to check the air tightness of the device; (3) Start the autoclave, fully stir the contents, and start the reaction after reaching the reaction temperature; (4) After the reaction is completed and the autoclave cools to room temperature, take out the product after the reaction in the autoclave for oil analysis.

[0011] Furthermore, the ratio of the mass of molybdenum in the catalyst precursor to the mass of the vacuum residue in step (1) is 100 to 500 μg / g.

[0012] Furthermore, the initial reaction pressure in step (2) is 6 to 10 MPa.

[0013] Furthermore, the reaction temperature of step (3) is 400-440° C., and the reaction time is 1 h.

[0014] Compared with the existing heavy oil slurry bed hydrogenation catalytic system, the present invention has the following significant advantages: 1. The present invention uses asphalt as a precursor, N and S sources containing heteroatoms as chelating ligand molecules, and soft templates as pore-forming agents. Metal molybdenum salts are added in situ during the self-assembly process to simultaneously achieve targeted anchoring of ligand molecules to molybdenum sites and their stable dispersion on asphalt. Finally, an atomic-level dispersed molybdenum catalyst system is constructed by in-situ sulfurization in a heavy oil slurry bed hydrogenation environment. The catalyst system has high metal dispersion, no subsequent treatment process, high product purity, no loss of metal active components, and high atomic utilization.

[0015] 2. The atomic-level dispersed molybdenum catalytic system prepared in situ in the heavy oil slurry bed hydrogenation environment of the present invention exhibits excellent heavy oil hydrogenation catalytic activity, stability and coke suppression ability, and can efficiently process low-quality heavy oil with high residual carbon, high metal content and high sulfur content, while effectively reducing the amount of coke produced during the reaction process.

[0016] 3. The atomic-level dispersed molybdenum catalytic system prepared by the present invention in situ in the heavy oil slurry bed hydrogenation environment is simple and controllable to operate, has good raw material applicability, low production cost, and has good industrial application value. DETAILED DESCRIPTION

[0017] The catalytic performance of the in-situ atomic-level dispersed molybdenum catalyst system constructed in the heavy oil slurry bed hydrogenation environment for vacuum residue hydrocracking reaction is further described below by specific examples. It should be noted that the following examples are only exemplary and the protection scope of the present invention is not limited to the following examples. Example 1

[0018] Weigh 1g of coal tar and 1g of melamine and disperse them in 100mL of anhydrous ethanol. After ultrasonic treatment, obtain a mixed solution and stir it on a stirring table; weigh 1g of soft template 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 thiocyanuric acid and stir at room temperature for 24h; put the mixed solution after stirring into a forced air drying oven, dry it at 80°C for 24h, and then transfer it to a mortar and grind it thoroughly to obtain a catalyst precursor.

[0019] The precursor was dispersed in FCC diesel (i.e., diesel obtained through catalytic cracking process) with an active metal input of 450 μg / g, and then fully mixed with 100 g of Qingdao Refining and Chemical Co., Ltd. vacuum residue and poured into an autoclave. After sulfurization, the atomic-level dispersed molybdenum catalyst system A1 was obtained. The air tightness of the device was checked, and the pressure was increased to an initial reaction pressure of 7 MPa. After the reaction temperature reached 425°C, the reaction was carried out for 1 hour. After the reaction was completed, the oil in the autoclave was cooled to room temperature and then taken out for oil product analysis. Example 2

[0020] Referring to Example 1, the soft template added was CTAC, and the atomic-level dispersed molybdenum catalytic system obtained was A2. Example 3

[0021] Referring to Example 1, the soft template added was CTAB, and the atomic-level dispersed molybdenum catalyst system obtained was A3. Example 4

[0022] Referring to Example 1, the soft template added is g-C3N4, and the atomic-level dispersed molybdenum catalytic system obtained is A4. Example 5

[0023] Referring to Example 1, the soft template added was ZnO, and the atomic-level dispersed molybdenum catalyst system obtained was A5. Example 6

[0024] Referring to Example 1, the soft template added was PVA, and the atomic-level dispersed molybdenum catalyst system obtained was A6. Example 7

[0025] Referring to Example 1, the soft template added was PVP, and the atomic-level dispersed molybdenum catalytic system obtained was A7. Example 8

[0026] Referring to Example 1, the soft template added was P123, and the atomic-level dispersed molybdenum catalyst system obtained was A8. Example 9

[0027] Referring to Example 1, the soft template added was F127, and the atomic-level dispersed molybdenum catalyst system obtained was A9.

[0028] Comparative Example 1 Weigh 1g of coal tar and 1g of melamine and disperse them in 100mL of anhydrous ethanol. After ultrasonic treatment, obtain a mixed solution and stir it on a stirring table; 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 thiocyanuric acid, and stir at room temperature for 24h; put the above mixed solution into a forced air drying oven, dry it at 80°C for 24h, and then transfer it to a mortar and grind it thoroughly to obtain a catalyst precursor.

[0029] The precursor was dispersed in FCC diesel (i.e., diesel obtained through catalytic cracking process) with an active metal input of 450 μg / g, and then fully mixed with 100 g of Qingdao Refining and Chemical Co., Ltd. vacuum residue and poured into an autoclave. After sulfurization, the atomic-level dispersed molybdenum catalyst system B1 was obtained. The airtightness of the device was checked, and the pressure was increased to an initial reaction pressure of 7 MPa. After the reaction temperature reached 425°C, the reaction was carried out for 1 hour. After the reaction was completed, the oil in the autoclave was cooled to room temperature and then taken out for oil product analysis.

[0030] Comparative Example 2 The hydrogenation performance of 100 g of Qingdao Refining and Chemical Vacuum Residue was evaluated without adding a catalyst, which was recorded as B2.

[0031] The raw materials for the experiments of hydrogenation performance evaluation in the above embodiments and comparative examples are all vacuum residue oil of Qingdao Refining and Chemical Company (properties are shown in Table 1), and the reactions are all carried out under the same reaction conditions of initial hydrogen pressure of 7 MPa, reaction temperature of 425°C, and reaction time of 1 h; the amount of precursor is 100-500 μg / g in terms of metal molybdenum. Table 2 shows the heavy oil hydrogenation evaluation results of embodiments 1-9 and comparative examples 1-2.

[0032] Table 1 Properties of Qingdao Refining and Chemical Vacuum Residue

[0033] Table 2 Evaluation results of heavy oil hydrogenation of Examples 1 to 9 and Comparative Examples 1 to 2

[0034] It can be found from Table 2 that the atomic-level dispersed molybdenum catalytic system constructed in situ in the heavy oil slurry bed hydrogenation environment prepared by the present invention exhibits certain catalytic activity and coke suppression performance. In Comparative Example 2 without adding a catalyst, the coke production is as high as 9.46wt.%, and the gas content is as high as 10.93wt.%. In Comparative Example 1, the coke production is reduced to 1.68wt.%, and the gas content is reduced to 7.36wt.%, which already has good catalytic activity and coke suppression performance. In Example 4, using g-C3N4 as a soft template, the coke production is further reduced to 0.75 wt.%, and the gas content is further reduced to 7.14wt.%, indicating that this template makes the metal Mo dispersed more evenly and stably on the asphalt carbon material, and the catalytic effect is the best. However, when other templates are added, the coke production increases instead, even higher than Comparative Example 1. Of course, it is normal for the error to be within 0.5%, and no further explanation is given. In summary, the atomically dispersed molybdenum catalytic system in situ constructed in the heavy oil slurry bed hydrogenation environment prepared by the present invention exhibits excellent heavy oil hydrogenation performance, significantly reduces the generation of by-products such as coke and gas, and promotes the efficient conversion of heavy oil.

Claims

1. An atomic-level dispersed molybdenum catalyst system constructed in situ in a heavy oil slurry bed hydrogenation environment, characterized in that: It includes a precursor, an active metal component, a heteroatom ligand and a soft template; the precursor is asphalt; the active metal component is molybdenum, which is highly dispersed on a porous carbon carrier in the form of single atoms or atomic clusters; the heteroatom ligands include N ligands and S ligands; wherein: the mass fraction of active metal molybdenum is 1wt.%~10wt.%, the mass fraction of N ligands is 1wt.%~8wt.%, the mass fraction of S ligands is 1wt.%~8wt.%, and the mass fraction of soft template is 10wt.%~20wt.%.

2. The in-situ atomic-level dispersed molybdenum catalyst 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, 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 hexacarbonyl molybdenum; the source of the N ligand is one or more of melamine, ammonia water, dicyandiamide, hydroxylamine chloride, and ethanolamine; the source of the S ligand is one or more of thiocyanuric acid, sulfur powder, dibenzyl disulfide, thiourea, and thioacetamide; the soft template is one or more of Urea, CTAC, CTAB, g-C3N4, ZnO, PVA, PVP, P123, and P127.

3. The method for preparing an atomically dispersed molybdenum catalyst system in situ in a heavy oil slurry bed hydrogenation environment according to claim 2, characterized in that: The following steps are involved: (1) Evenly dispersing asphalt and N ligand source in anhydrous ethanol to obtain a mixed solution I; (2) mixing the soft template with deionized water and adding the mixture to the mixed solution I obtained in step (1) which is in a stirring state, to obtain a mixed solution II; (3) dissolving the molybdenum source compound in deionized water and adding the solution dropwise to the mixed solution II obtained in step (2) which is in a stirring state, to obtain a mixed solution III; (4) adding the S ligand source to the mixed solution III obtained in step (3) to obtain a mixed solution IV, and continuing to stir the mixed solution IV to ensure that the reaction is complete; (5) drying the mixed solution IV after sufficient reaction in step (4) to obtain a catalyst precursor; (6) pre-dispersing the catalyst precursor obtained in step (5) in FCC diesel, and then fully mixing it with vacuum residue oil and dispersing it in an autoclave; (7) The autoclave is heated to a certain temperature and then in-situ sulfurization is carried out to obtain an atomically dispersed molybdenum catalyst system.

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

5. The method for preparing an atomically dispersed molybdenum catalyst system in situ in a heavy oil slurry bed hydrogenation environment according to claim 3, characterized in that: The stirring in step (4) is carried out at room temperature for 24 hours to ensure that the reaction is complete; the drying temperature in step (5) is 70 to 100° C. and the drying time is 12 to 36 hours; and the certain temperature for in-situ vulcanization in step (7) is 200 to 300° C.

6. The method for preparing an atomically dispersed molybdenum catalyst system in situ in a heavy oil slurry bed hydrogenation environment according to claim 3, characterized in that: Ultrasonic treatment is used in the step (1) when the asphalt, the N ligand source and the anhydrous ethanol are mixed, in the step (2) when the soft template agent and the deionized water are mixed, and in the step (3) when the molybdenum source compound and the deionized water are mixed.

7. Application of an atomically dispersed molybdenum catalyst system in situ constructed in a heavy oil slurry bed hydrogenation environment obtained by the preparation method according to any one of claims 3 to 6 in slurry bed heavy oil hydrogenation, characterized in that: The following steps are involved: (1) Pre-dispersing the catalyst precursor into FCC diesel, then fully mixing it with vacuum residue and placing it into an autoclave; (2) Purge the autoclave with hydrogen, exhaust the air in the autoclave, pressurize it to the initial reaction pressure, and use a hazardous gas detector to check the air tightness of the device; (3) Start the autoclave, fully stir the contents, and start the reaction after reaching the reaction temperature; (4) After the reaction is completed and the autoclave cools to room temperature, take out the product after the reaction in the autoclave for oil analysis.

8. The use of an atomically dispersed molybdenum catalyst system constructed in situ in a heavy oil slurry bed hydrogenation environment according to claim 7 in slurry bed heavy oil hydrogenation, characterized in that: In the step (1), the ratio of the mass of molybdenum in the catalyst precursor to the mass of the vacuum residue oil is 100 to 500 μg / g.

9. The use of an atomically dispersed molybdenum catalyst system constructed in situ in a heavy oil slurry bed hydrogenation environment in claim 7 in slurry bed heavy oil hydrogenation, characterized in that: The initial reaction pressure in step (2) is 6-10 MPa.

10. The use of an atomically dispersed molybdenum catalyst system constructed in situ in a heavy oil slurry bed hydrogenation environment in claim 7 in slurry bed heavy oil hydrogenation, characterized in that: The reaction temperature of step (3) is 400-440° C., and the reaction time is 1 h.

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