A bio-based oil-soluble molybdenum catalyst, a preparation method and application thereof

Abstract

The present application belongs to the technical field of biological oil catalytic hydrogenation, and particularly relates to a bio-based oil-soluble molybdenum catalyst, a preparation method and application thereof. The preparation method of the bio-based oil-soluble molybdenum catalyst provided by the present application comprises: mixing a molybdenum source, a bio-based linear organic acid with a carbon atom number of 16 or more and an additive, heating and reacting, and separating to obtain the bio-based oil-soluble molybdenum catalyst; the additive is selected from at least one of tetrahydro naphthalene and decahydro naphthalene. The bio-based oil-soluble molybdenum catalyst green material obtained by the present application has optimal activity and high dispersibility when used, can realize more sufficient mixing with raw materials, forms nano high-dispersed molybdenum sulfide through sulfuration, and realizes high-efficiency hydrogenation refining of oil products through the joint action of hydrogen and sulfur, while reducing the sulfur, oxygen and metal residues in the product oil.

Description

A bio-based oil-soluble molybdenum catalyst, its preparation method and application Technical Field

[0001] This invention belongs to the field of bio-oil catalytic hydrogenation technology, specifically relating to a bio-based oil-soluble molybdenum catalyst, its preparation method, and its application. Background Technology

[0002] With the depletion of oil resources and the global consensus on carbon emission reduction, the utilization of more renewable resources is receiving increasing attention. For example, various bio-oil wastes such as rancid oil and waste animal and vegetable oils can be hydrorefined to obtain the same performance as existing petrochemical-based finished oils, thereby meeting the needs of carbon emission reduction and clean use.

[0003] These bio-oil wastes often possess characteristics such as high metal content, high acid value, high residual carbon, high sulfur content, high oxygen content, and high nitrogen content. Conventional fixed-bed hydrogenation units typically struggle to cope with these challenges, leading to problems like coking, clogging, corrosion, and uneven heat release, making long-term continuous operation difficult. Therefore, some companies have attempted to overcome these difficulties by using fluidized bed or slurry bed technologies. Slurry bed hydrogenation technology, in particular, effectively overcomes the problems encountered in conventional fixed-bed hydrogenation by allowing for on-demand catalyst addition, enabling longer operating cycles. In slurry bed technology, the key to success lies in using fine catalyst particles or soluble catalysts to achieve high dispersion, high activity, and low cost. Oil-soluble catalysts, which dissolve effectively in the feedstock, exhibit excellent hydrogenation performance and are considered ideal catalysts.

[0004] Chinese patent document CN103977822A discloses the preparation of oil-soluble catalysts by reacting reduced metals with organic amines. Chinese patent document CN105289750A discloses the preparation of oil-soluble catalysts by reacting metal salts with carboxylic acid organic compounds, alcohols, and sulfiding agents. Chinese patent document CN1362492A discloses the preparation of oil-soluble catalysts by reacting Mo and W metals with benzo[a]pyrene and its derivatives. Chinese patent document CN103980320A discloses a method for preparing a sulfur-containing organic molybdenum precursor, which involves reacting a sulfur-containing organic compound generated by reacting a polycarbonate alcohol with phosphorus pentasulfide with a neutral aqueous solution of molybdenum in the presence of an acidic cation exchange resin to prepare a sulfur-containing oil-soluble catalyst. Chinese patent document CN111644208A discloses a method for preparing an oil-soluble suspended bed hydrogenation catalyst, which involves uniformly mixing and drying a metal salt with a surfactant to obtain a catalyst precursor, which is then dissolved in oil to obtain a suspended bed hydrogenation catalyst. The reported methods for preparing these catalysts are quite complex, resulting in high costs. Furthermore, most of them are prepared using traditional non-bio-based chemicals, which can easily cause pollution during production and use. The resulting catalysts have poor activity and dispersibility, and their catalytic effect needs to be improved. The catalytic products also contain high levels of residual impurities such as sulfur, oxygen, and metals.

[0005] Therefore, how to improve the preparation method of oil-soluble catalysts to make them more economical, simple, efficient and green, and achieve optimal activity and high dispersibility in the application process is the technical problem that this invention urgently needs to solve. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing technologies, such as poor catalytic effect of oil-soluble catalysts, non-bio-based chemical raw materials, high residual impurities in catalytic products, complex catalyst preparation process, high cost, and easy pollution, so as to provide a bio-based oil-soluble molybdenum catalyst, its preparation method and application.

[0007] This invention provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0008] A bio-based oil-soluble molybdenum catalyst was obtained by mixing a molybdenum source, a bio-based linear organic acid with ≥16 carbon atoms, and an auxiliary agent, heating the mixture, and then separating the reactants.

[0009] The auxiliary agent is selected from at least one of tetrahydronaphthalene and decahydronaphthalene.

[0010] Preferably, the bio-based linear organic acid has 16 to 18 carbon atoms;

[0011] Preferably, the bio-based linear organic acid is selected from at least one of oleic acid, linoleic acid, palmitic acid, and stearic acid;

[0012] And / or, the adjuvant is tetrahydronaphthalene and decahydronaphthalene;

[0013] The molar ratio of tetrahydronaphthalene to decahydronaphthalene is (2-2.5):(2-2.5).

[0014] Preferably, the molybdenum source is selected from at least one of molybdenum oxide, molybdenum oxide hydrate, and molybdenum salt;

[0015] Preferably, the molybdenum source is selected from at least one of molybdenum trioxide, ammonium molybdate, and molybdic acid.

[0016] Preferably, the molar ratio of the molybdenum source to the bio-based linear organic acid is 1:3 to 4;

[0017] And / or, the molar ratio of the adjuvant to the bio-based linear organic acid is 1 to 2:1.

[0018] Preferably, the heating reaction temperature is 190–250°C, and the heating reaction time is 1–3 hours.

[0019] And / or, the heating reaction is carried out under stirring at a speed of 50 to 200 rpm.

[0020] Preferably, the heating reaction further includes introducing at least one gas selected from nitrogen, carbon dioxide, and hydrogen;

[0021] And / or, the separation includes filter residue and distilled filtrate;

[0022] The distillation pressure is -50 to 150 kPa, and the distillation temperature is 200 to 230 °C.

[0023] The additives are separated by distillation of the filtrate, and the separated additives can be recycled. Optionally, distillation can be performed using a distillation column.

[0024] This invention provides a bio-based oil-soluble molybdenum catalyst prepared by the above-described method, wherein the molybdenum content accounts for 4-12% of the total mass of the bio-based oil-soluble molybdenum catalyst.

[0025] Optionally, the bio-based oil-soluble molybdenum catalyst is wine-red in color.

[0026] This invention provides an application of the above-described bio-based oil-soluble molybdenum catalyst in the preparation of biofuel oil.

[0027] This invention also provides a method for preparing biofuel oil, comprising the following steps:

[0028] The aforementioned bio-based oil-soluble molybdenum catalyst is dispersed into bio-oil waste, and hydrogen and hydrogen sulfide are introduced to react, yielding biofuel oil.

[0029] Preferably, the molybdenum element in the bio-based oil-soluble molybdenum catalyst accounts for 100 to 2000 ppm of the total mass of the bio-based oil-soluble molybdenum catalyst and bio-oil waste;

[0030] And / or, the reaction pressure is 6–20 MPa, and the reaction temperature is 260–350 °C;

[0031] Preferably, the reaction pressure is 7–14 MPa;

[0032] And / or, the standard volume ratio of the hydrogen to the bio-oil waste is 400 to 2000:1;

[0033] And / or, the volume of the hydrogen sulfide accounts for 400 to 1500 ppm of the total volume of the hydrogen and hydrogen sulfide;

[0034] And / or, the bio-based oil-soluble molybdenum catalyst is dispersed in the bio-oil waste in stages, with each stage of dispersion having a dilution factor of 5 to 15 times;

[0035] And / or, the bio-oil waste is at least one of swill oil, rancid oil, gutter oil, rancid palm oil, and acidified palm oil;

[0036] Optionally, the preparation method further includes a purification step, which includes stripping and fractionation of the reaction system to finally obtain the biofuel oil.

[0037] The oil-soluble molybdenum catalyst of this invention catalyzes hydrogenation, effectively reducing the content of organic sulfur and organic oxygen in biofuel oil products. At the same time, most metal ions are separated from the biofuel oil. Inorganic hydrogen sulfide, water, and metal impurities are separated through conventional purification steps such as stripping and fractionation, resulting in purified biofuel oil.

[0038] The technical solution of this invention has the following advantages:

[0039] 1. The preparation method of the bio-based oil-soluble molybdenum catalyst provided by the present invention includes the following steps: mixing a molybdenum source, a bio-based linear organic acid with ≥16 carbon atoms, and an auxiliary agent, heating the mixture to react, and separating the mixture to obtain the bio-based oil-soluble molybdenum catalyst; the auxiliary agent is selected from at least one of tetrahydronaphthalene and decahydronaphthalene. The present invention uses a bio-based linear organic acid with ≥16 carbon atoms, which reacts rapidly with molybdenum compounds under the promotion of specific auxiliary agents such as tetrahydronaphthalene and decahydronaphthalene. The specific auxiliary agent can also expand the molecular dispersion gap, inhibit the concentrated reaction of the organic acid and the molybdenum source or other side reactions, and facilitate the formation of molybdenum organic acid with a molybdenum valence of 3-4. A high-concentration bio-based macromolecular linear-chain oil-soluble molybdenum catalyst was prepared. The preparation process is more economical, simple, and efficient. Bio-based linear-chain organic acids do not contain petroleum processing byproducts, making the preparation process greener. The resulting oil-soluble molybdenum catalyst is itself a green material for carbon reduction, which can be better applied to bio-new energy without causing carbon pollution from petroleum or coal. When molybdenum is converted into molybdenum sulfide in the reaction system, its original organic acid can be directly converted into bioenergy products by hydrogenation without pollution. Simultaneously, because the formed macromolecular organic acid molybdenum has properties similar to oils, it can be better dispersed in the raw materials during hydrogenation, achieving a uniform and highly dispersed effect. The bio-based oil-soluble molybdenum catalyst prepared by the method of this invention exhibits optimal activity and high dispersibility when processing oils, allowing for more thorough mixing with raw materials. Sulfation occurs within the reactor, forming nano-sized, highly dispersed molybdenum sulfide, which, in conjunction with hydrogen, achieves efficient hydrogenation refining of oils while effectively removing sulfur, oxygen, and metallic impurities from the product oil.

[0040] 2. The bio-based oil-soluble molybdenum catalyst provided by this invention can be fully dispersed in the feedstock oil, and the molybdenum sulfide formed will not agglomerate under the blockage of bio-oil waste, and has a large contact area. Therefore, it can be used to realize a series of hydrogenation reactions in continuous production fluidized bed, slurry bed, packed bed, or non-continuous production batch reactor.

[0041] 3. The method for preparing biofuel oil provided by the present invention includes the following steps: dispersing the bio-based oil-soluble molybdenum catalyst in bio-oil waste, introducing hydrogen and hydrogen sulfide to react, and obtaining biofuel oil. The bio-based oil-soluble molybdenum catalyst of the present invention first reacts with hydrogen sulfide gas to generate nano-sized molybdenum sulfide, thereby possessing hydrogenation activity. Due to the high dispersibility of the bio-based oil-soluble molybdenum catalyst, the generated molybdenum sulfide also has a good dispersion and dilution effect in the raw materials. Furthermore, the formed molybdenum sulfide will not agglomerate under the blockage of bio-oil waste and has a large contact area. Under the action of hydrogen, it achieves hydrogenation deoxygenation, olefin protection, hydrogenation demetallization, desulfurization, denitrification, dephosphorization, desiliconization, and other impurity removal hydrogenation reactions. This not only improves the biofuel yield but also reduces sulfur, oxygen, and metal residues in the biofuel, ultimately producing pure biofuel oil. Detailed Implementation

[0042] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0043] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0044] Example 1

[0045] This embodiment provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0046] Oleic acid, molybdenum trioxide, and tetrahydronaphthalene in a molar ratio of 4:1:6 were placed in a stirred tank and heated to 200°C for 3 hours with a stirring speed of 60 rpm. After the reaction was complete, the residue was filtered, and the filtrate was distilled in a fractionating column at a pressure of 50 kPa and a temperature of 210°C to obtain molybdenum oleate. Inductively coupled plasma (ICP) analysis showed that the molybdenum content was 4.3%.

[0047] Example 2

[0048] This embodiment provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0049] Palmitic acid, ammonium molybdate, and decahydronaphthalene in a molar ratio of 3.5:1:7 were placed in a stirred tank. Nitrogen gas was introduced into the bottom of the tank, and the mixture was heated to 250°C and reacted for 1.5 hours with a stirring speed of 150 rpm. After the reaction was complete, the residue was filtered, and the filtrate was distilled under reduced pressure in a fractionating column at a pressure of -50 kPa and a temperature of 200°C to obtain molybdenum palmitate. The molybdenum content was determined to be 7.8% by inductively coupled plasma (ICP) analysis.

[0050] Example 3

[0051] This embodiment provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0052] Stearic acid, molybdic acid, decahydronaphthalene, and tetrahydronaphthalene in a molar ratio of 3:1:2:2.5 were placed in a stirred tank, and hydrogen gas was introduced into the bottom of the tank. The mixture was heated to 230°C and reacted for 2 hours with a stirring speed of 180 rpm. After the reaction was complete, the residue was filtered, and the filtrate was distilled in a fractionating column at a pressure of 110 kPa and a temperature of 215°C to obtain molybdenum stearate. The molybdenum content was determined to be 10.2% by inductively coupled plasma (ICP) analysis.

[0053] Example 4

[0054] This embodiment provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0055] Linoleic acid, molybdenum trioxide, and tetrahydronaphthalene in a molar ratio of 3:1:3 were placed in a stirred tank and heated to 220°C for 2 hours with a stirring speed of 120 rpm. After the reaction was complete, the residue was filtered, and the filtrate was distilled under reduced pressure in a fractionating column at a pressure of -20 kPa and a temperature of 200°C to obtain molybdenum linoleate. Inductively coupled plasma (ICP) analysis showed that the molybdenum content was 8.5%.

[0056] Example 5

[0057] This embodiment provides a method for preparing a bio-based oil-soluble molybdenum catalyst, comprising the following steps:

[0058] Palmitic acid, ammonium molybdate, and decahydronaphthalene in a molar ratio of 4:1:8 were placed in a stirred tank and heated to 240°C for 2.5 hours with a stirring speed of 200 rpm. After the reaction was complete, the residue was filtered, and the filtrate was distilled in a fractionating column at a pressure of 101 kPa and a temperature of 200°C to obtain molybdenum palmitate. Inductively coupled plasma (ICP) analysis showed that the molybdenum content was 11.3%.

[0059] Comparative Example 1

[0060] This comparative example provides a method for preparing an oil-soluble Mo-based suspended bed hydrogenation catalyst, the method comprising the following steps:

[0061] 1) Weigh 1.236g of ammonium molybdate tetrahydrate and grind vigorously for 10min; weigh 3.519g of dioctadecyldimethylammonium chloride and grind vigorously for 10min; mix the two together and grind vigorously for 0.5h.

[0062] 2) Place the above product into a vacuum drying oven and dry it under vacuum at 180°C for 5 hours.

[0063] 3) Take out the catalyst precursor, grind it thoroughly, and dissolve it in 100 mL of white oil (lubricating oil base oil) to obtain an oil-soluble Mo-based suspension bed hydrogenation catalyst.

[0064] The molybdenum content was determined to be 0.35% using inductively coupled plasma (ICP) analysis.

[0065] Comparative Example 2

[0066] This comparative example provides a method for preparing a bio-based oil-soluble molybdenum catalyst, which differs from Example 1 in that it does not include the auxiliary agent tetrahydronaphthalene.

[0067] Comparative Example 3

[0068] This comparative example provides a method for preparing a bio-based oil-soluble molybdenum catalyst, which differs from Example 1 in that it uses an equimolar amount of benzene as an auxiliary agent instead of tetrahydronaphthalene.

[0069] Test case

[0070] The bio-based oil-soluble molybdenum catalysts prepared in Examples 1-5 and the catalysts prepared in Comparative Examples 1-3 were added to a pre-dilution stirred tank at 90°C and mixed with bio-oil waste for pre-dilution. The weight ratio of molybdenum atoms to bio-oil was 10 times the final required concentration (for example, if the target molybdenum content is 500 ppm, it is diluted to a molybdenum content of 5000 ppm). The pre-diluted mixture was then fed into the next stirred tank, and the same bio-oil waste was added again, controlling the weight ratio of molybdenum atoms to bio-oil waste to reach a certain level. The target concentration is set (e.g., 500 ppm). The mixture then enters a reactor, where hydrogen sulfide and hydrogen are introduced. Ultimately, the mass of molybdenum in the bio-based oil-soluble molybdenum catalyst accounts for 100–2000 ppm of the total mass of the bio-based oil-soluble molybdenum catalyst and bio-oil waste. The standard volume ratio of hydrogen to bio-oil waste reaches 400–2000:1, and the volume of hydrogen sulfide accounts for 400–1500 ppm of the total volume of hydrogen and hydrogen sulfide. Hydrogenation refining is then carried out under conditions of 6–20.0 MPa and 260–350 °C. The reaction product is stripped at 110 kPa and 110 °C to remove water and hydrogen sulfide gas, and then distilled in a fractionation tower at 360 °C to obtain a diesel fraction. The bottom of the tower contains residual heavy oil. The obtained diesel fraction is the biofuel product, biodiesel. Specific reaction conditions are shown in Table 1.

[0071] The weight of refined biodiesel was measured and compared with the bio-oil waste entering the reactor to obtain the biodiesel yield. The sulfur content of the hydrorefined biodiesel was tested using the method of NB / T 10897-2021, and the metal impurity content of the hydrorefined biodiesel was analyzed using inductively coupled plasma (ICP). The measured metal impurities included iron, calcium, potassium, magnesium, manganese, nickel, molybdenum, vanadium, and zinc. The oxygen content of the hydrorefined biodiesel was tested using an oxygen element analyzer. The test results are shown in Table 1.

[0072] As can be seen from Table 1, the bio-based macromolecular straight-chain oil-soluble molybdenum catalysts of the present invention all achieved good hydrogenation effects. The residual amounts of sulfur, oxygen, and metals in biodiesel and the yield of biodiesel were all better than those of the catalysts in Comparative Examples 1-3.

[0073] Table 1

[0074]

[0075] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a bio-based oil-soluble molybdenum catalyst, characterized in that, The preparation method consists of the following steps: mixing a molybdenum source, a bio-based linear organic acid with ≥16 carbon atoms, and an auxiliary agent, heating the mixture to react, and separating the mixture to obtain a bio-based oil-soluble molybdenum catalyst; the auxiliary agent is selected from at least one of tetrahydronaphthalene and decahydronaphthalene; the molar ratio of the auxiliary agent to the bio-based linear organic acid is 1~2:1; the heating reaction further includes introducing at least one gas selected from nitrogen, carbon dioxide, and hydrogen.

2. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 1, characterized in that, The bio-based linear organic acid has 16 to 18 carbon atoms; and / or the auxiliary is tetrahydronaphthalene and decahydronaphthalene; the molar ratio of tetrahydronaphthalene and decahydronaphthalene is (2 to 2.5): (2 to 2.5).

3. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 2, characterized in that, The bio-based linear organic acid is selected from at least one of oleic acid, linoleic acid, palmitic acid, and stearic acid.

4. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 1, characterized in that, The molybdenum source is selected from at least one of molybdenum oxide, molybdenum oxide hydrate, and molybdenum salt.

5. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 4, characterized in that, The molybdenum source is selected from at least one of molybdenum trioxide, ammonium molybdate, and molybdic acid.

6. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 1, characterized in that, The molar ratio of the molybdenum source to the bio-based linear organic acid is 1:3~4.

7. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 1, characterized in that, The heating reaction is carried out at a temperature of 190~250℃ for a duration of 1~3h; and / or the heating reaction is carried out under stirring at a speed of 50~200rpm.

8. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 1, characterized in that, The separation includes filter residue and distilled filtrate.

9. The method for preparing the bio-based oil-soluble molybdenum catalyst according to claim 8, characterized in that, The distillation pressure is -50~150KPa, and the distillation temperature is 200~230℃.

10. A bio-based oil-soluble molybdenum catalyst prepared by the method of claim 1, characterized in that, In the bio-based oil-soluble molybdenum catalyst, the molybdenum content accounts for 4-12% of the total mass of the bio-based oil-soluble molybdenum catalyst.

11. The application of the bio-based oil-soluble molybdenum catalyst of claim 10 in the preparation of biofuel oil.

12. A method for preparing biofuel oil, characterized in that, The process includes the following steps: dispersing the bio-based oil-soluble molybdenum catalyst of claim 10 into bio-oil waste, introducing hydrogen and hydrogen sulfide to react, and obtaining biofuel oil.

13. The method for preparing biofuel oil according to claim 12, characterized in that, The bio-based oil-soluble molybdenum catalyst comprises 100-2000 ppm of molybdenum by mass of the total mass of the bio-based oil-soluble molybdenum catalyst and the bio-oil waste; and / or, the reaction pressure is 6-20.0 MPa and the reaction temperature is 260-350 °C; and / or, the standard volume ratio of hydrogen to the bio-oil waste is 400-2000:1; and / or, the volume of hydrogen sulfide comprises 400-1500 ppm of the total volume of hydrogen and hydrogen sulfide; and / or, the bio-based oil-soluble molybdenum catalyst is dispersed into the bio-oil waste in stages, with each stage having a dilution factor of 5-15 times; and / or, the bio-oil waste is at least one of swill oil, rancid oil, and acidified palm oil.

14. The method for preparing biofuel oil according to claim 13, characterized in that, The bio-oil waste is palm oil.

15. The method for preparing biofuel oil according to claim 13 or 14, characterized in that, The reaction is carried out at a pressure of 7-14 MPa.

16. The method for preparing biofuel oil according to claim 13 or 14, characterized in that, The preparation method further includes a purification step, which includes stripping and fractionation of the reaction system to finally obtain the biofuel oil.

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