A method for producing bio-jet fuel using plant pitch

Abstract

This application discloses a method for producing bio-jet fuel from plant bitumen, belonging to the field of plant bitumen recycling technology. The method includes the following steps: (1) preheating and reducing the viscosity of the purified plant bitumen, and pre-mixing it with hydrogen to obtain a premixed hydrogen feedstock; (2) adding an oil-soluble catalyst to the premixed hydrogen feedstock, and obtaining intermediate product I after a first-stage hydrogenation; (3) adding intermediate product I to a fixed-bed reactor, and performing a second-stage hydrogenation under the action of a hierarchical porous composite molecular sieve catalyst to obtain intermediate product II; (4) fractionating intermediate product II to obtain bio-jet fuel. This method preheats and reduces the viscosity of plant bitumen, and sequentially uses an oil-soluble catalyst and a hierarchical porous composite molecular sieve catalyst for hydrodeoxygenation, hydrocracking, and hydroisomerization, which can improve the catalytic efficiency and catalytic stability of plant bitumen, thereby improving the isomerization selectivity, yield, and quality of bio-jet fuel.

Description

Technical Field

[0001] This application relates to a method for producing biofuel from plant bitumen, belonging to the field of plant bitumen recycling technology. Background Technology

[0002] Vegetable bitumen is a byproduct of vegetable oil processing, mainly derived from high-viscosity, high-boiling-point residues produced during vegetable oil refining (such as degumming, deacidification, decolorization, and deodorization). It is named for its dark brown, viscous appearance, resembling petroleum asphalt, and accounts for approximately 10 wt% of the total mass of vegetable oil residue. In the past, vegetable bitumen was often directly burned as heavy oil, resulting in extremely low resource utilization.

[0003] From a compositional perspective, plant-based asphalt is complex and rich in high-value substances. Its core components include high molecular weight glycerides and polymeric oils (30wt%-60wt%), mixed free fatty acids (10wt%-30wt%), phytosterols (5wt%-10wt%), and natural vitamin E (0.5wt%-5wt%). The high molecular weight glycerides and polymeric oils primarily originate from the polymerization, cyclization, and oxidation of triglycerides during high-temperature refining, forming dimers, trimers, and larger molecules. This is the main reason for its high viscosity. Mixed free fatty acids are core raw materials for producing biodiesel, bio-jet fuel, and other biofuels. Phytosterols and vitamin E can be recycled as high-value-added chemicals. However, in terms of physicochemical properties, plant-based asphalt has extremely high viscosity, is semi-solid at room temperature, and its molecular structure is rich in long-chain fatty acids, esters, gums, and a small amount of aromatic compounds. It also has a high oxygen content and contains some metallic impurities and polar groups. These characteristics directly affect its compatibility with catalytic hydrogenation processes.

[0004] As a renewable biomass resource, the resource utilization of plant bitumen aligns with the global trend of environmental protection and sustainable development. It has gradually shifted from traditional combustion disposal to fields such as biofuel preparation, waterproof material production, and road construction. Among these, catalytic hydrogenation into biojet fuel and biodiesel is one of the core pathways to enhance its added value.

[0005] Currently, there is some research on the production of clean fuels such as biodiesel and biojet fuel from plant asphalt. For example, patent CN104312612B involves washing plant asphalt with water to obtain an oil phase, followed by alkaline treatment and saponification of the oil phase to obtain clean fuel. However, this method has drawbacks such as complex processes, large wastewater generation, and low product utilization, making it difficult to use industrially. Another example is patent CN110129086B, which discloses a method for producing biojet fuel through catalytic cracking of plant asphalt. This method involves mixing plant asphalt with a catalyst, followed by cracking and distillation to obtain biojet fuel. This non-hydrogen-dependent catalytic cracking method results in a higher impurity content in the product, making it difficult for the biojet fuel to meet the required freezing point. Therefore, if it is desired to obtain a product with high purity and a high freezing point to meet the aviation industry's high standards for jet fuel, a hydrogenation catalytic cracking method is still necessary.

[0006] However, the applicant discovered that the method of producing bio-jet fuel from plant bitumen using hydrogenation catalysis faces the following insurmountable difficulties: 1) The high viscosity of plant-based asphalt leads to decreased fluidity and mass transfer efficiency, making it easy to clog process pipelines and reactors, causing a surge in pressure drop and resulting in shutdown accidents; 2) Plant asphalt contains many impurities, gums and polar groups, which are easily adsorbed on the active sites of solid catalysts in fixed-bed reactors, leading to solid catalyst poisoning, coking and deactivation. Frequent regeneration or replacement of catalysts is required, which increases operating costs. In addition, the selectivity and stability requirements of catalysts are extremely high. 3) Plant-based bitumen has a higher oxygen content than other petroleum-based raw materials. During the hydrogenation process, a large amount of hydrogen is required for the deoxygenation reaction. If the hydrogenation and deoxygenation are insufficient in industrial production, the oxidation stability of bio-jet fuel will decrease.

[0007] While methods for producing biojet fuel from plant bitumen can draw inspiration from those for biodiesel production, such as the processing method disclosed in CN112552947B, current methods still cannot solve the aforementioned problems. The most viscous components of plant bitumen (high molecular weight glycerides and polymeric oils) cannot be directly fed into the fixed-bed reactor of traditional hydrogenation processes; otherwise, it would immediately lead to solid catalyst bed blockage, a surge in pressure drop, and rapid catalyst deactivation. Therefore, there is an urgent need for a new catalytic hydrogenation process to effectively process and utilize plant bitumen to improve the isomer selectivity, yield, and product quality of biojet fuel. Summary of the Invention

[0008] To address the aforementioned issues, a method for producing bio-jet fuel using plant bitumen is provided. This method involves preheating and reducing the viscosity of the plant bitumen, followed by sequential hydrodeoxygenation, hydrocracking, and hydroisomerization using an oil-soluble catalyst and a hierarchical porous composite molecular sieve catalyst. This improves the catalytic efficiency and stability of the plant bitumen, thereby enhancing the isomerization selectivity, yield, and quality of the bio-jet fuel.

[0009] This application provides a method for producing bio-jet fuel using plant bitumen, comprising the following steps: (1) The impurity-removed plant asphalt is preheated and viscosity reduced, and hydrogen is premixed according to the hydrogen-to-oil ratio (800-1000):1 to obtain premixed hydrogen raw material; (2) Add an oil-soluble catalyst to the premixed hydrogen feedstock, and after one stage of hydrogenation, obtain intermediate product I; (3) Add intermediate product I to a fixed bed reactor and perform two-stage hydrogenation under the action of a multi-level porous composite molecular sieve catalyst to obtain intermediate product II. The multi-level porous composite molecular sieve catalyst includes a composite support and an active metal component supported on the composite support. (4) The intermediate product II was fractionated to obtain bio-jet fuel.

[0010] This application employs a stepwise catalytic process involving preheating and viscosity reduction of plant bitumen feedstock, premixing hydrogen, and using an oil-soluble catalyst and a hierarchical porous composite molecular sieve catalyst. This reduces the viscosity of the plant bitumen, improves its mass transfer efficiency, maintains the activity and stability of the catalyst, and consequently improves the yield, isomer selectivity, and quality of bio-jet fuel, ensuring that the freezing point and oxidation stability of the bio-jet fuel meet high standards. The oil-soluble catalyst used in step (2) of this application is a liquid catalyst, which can quickly mix with the plant bitumen feedstock for catalytic hydrogenation. If the oil-soluble catalyst in step (2) is omitted, the bio-jet fuel yield will be as low as 15%, making it difficult to apply.

[0011] Optionally, the preheating and viscosity-reducing temperature of the plant-based asphalt in step (1) is 80-120℃.

[0012] This temperature can reduce the viscosity of plant asphalt and improve the mixing effect with hydrogen, thereby obtaining a premixed hydrogen feedstock with high mixing uniformity.

[0013] Optionally, the preheating and viscosity reduction of the plant-based asphalt in step (1) specifically involves: Add circulating oil, which is 1-10 times the weight of the plant asphalt, to the purified plant asphalt. While stirring, heat to 80-120℃ and stir for at least 30 minutes after maintaining the temperature.

[0014] This application uses circulating oil to reduce the viscosity of plant-based asphalt, which can reduce the cost of reducing the viscosity of plant-based asphalt and will not introduce new impurities, making it more conducive to industrial production.

[0015] Preferably, the circulating oil is 5-10 times that of plant bitumen.

[0016] Optionally, in step (2), the hydrogenation reaction is carried out at a temperature of 320-360℃, a pressure of 2-6 MPa, and a liquid hourly space velocity of 0.5-1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is (1000-1500):1.

[0017] The first stage of hydrogenation involves hydrodeoxygenation and hydrocracking. The parameters mentioned above enable the oil-soluble catalyst to efficiently catalyze the hydrogenation of the premixed hydrogen feedstock. This allows the hydrogen added in this stage to react efficiently with the hydrogen in the premixed hydrogen feedstock to achieve deoxygenation and cracking, which is beneficial for the subsequent hydroisomerization to efficiently produce bio-jet fuel.

[0018] Due to the high viscosity and complex composition of plant pitch, when using a single slurry bed reactor for single-stage hydrogenation, although the isomerization selectivity, jet fuel yield, and freezing point of the product can be improved compared to existing processing technologies, the isomerization selectivity cannot reach more than 70%. In order to further improve the isomerization selectivity and yield, the applicant used two slurry bed reactors for single-stage hydrogenation, with the same amount of oil-soluble catalyst added to each slurry bed reactor.

[0019] Optionally, the hydrogenation in step (2) is divided into two stages, specifically: R1: Reaction temperature 340-360℃, pressure 5-6MPa, liquid hourly space velocity 0.5-1.0h. -1 The hydrogen-to-oil ratio is (1400-1500):1, and the amount of oil-soluble catalyst added is 400-1000 ppm; R2: Reaction temperature 300-330℃, pressure 2-4MPa, liquid hourly space velocity 1.0-1.5h. -1 The hydrogen-to-oil ratio is (1000-1300):1, and the amount of oil-soluble catalyst added is 400-1000 ppm.

[0020] This application divides the hydrotreating process into two stages. Initially, the plant pitch has a high viscosity; therefore, stage R1 is conducted at a higher temperature, pressure, and hydrogen-to-oil ratio to rapidly reduce the viscosity of the plant pitch, achieving preliminary hydrodeoxidation and hydrocracking. After stage R1, the feedstock viscosity decreases, and stage R2 is conducted at a lower temperature, pressure, and hydrogen-to-oil ratio to achieve deep hydrodeoxidation and hydrocracking. The combination of these two stages can improve the yield of bio-jet fuel, significantly lower the freezing point, improve the low-temperature fluidity of bio-jet fuel, and enhance product stability. Furthermore, it enables efficient utilization of hydrogen, reducing hydrogen consumption and thus lowering the production cost of bio-jet fuel.

[0021] Optionally, the second-stage hydrogenation in step (3) is carried out at a reaction temperature of 300-360℃, a pressure of 2-6 MPa, and a liquid hourly space velocity of 0.5-1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is (1000-2000):1.

[0022] Specifically, the composite support is impregnated in a solution containing an active metal component, followed by drying, calcination, and reduction to obtain the hierarchical porous composite molecular sieve catalyst. The impregnation of this active metal component enables uniform loading of the active metal component, thereby improving the catalytic effect of the catalyst.

[0023] Optionally, the active metal component includes metals from Group VIB and / or Group VIII.

[0024] Preferably, the active metal component includes at least one selected from nickel, cobalt, iron, zinc, zirconium, molybdenum, tungsten, and niobium.

[0025] The active metal component used in the catalyst of this application is a non-precious metal catalyst, which reduces the cost by 40%-90% compared with precious metal catalysts, and is more suitable for industrial application.

[0026] Optionally, the composite carrier is immersed in a solution containing active metal components and then dried at a temperature of 80-120℃ for 10-12 hours, and calcined at a temperature of 500-600℃ for 4-6 hours.

[0027] Optionally, the composite support is a hierarchical porous composite molecular sieve, and its preparation steps are as follows: H1: Using aluminum, phosphorus, silicon and water as reactants in a molar ratio of 1:(0.8-1.0):(0.1-0.6):(40-60), where aluminum is calculated as Al2O3, phosphorus as P2O5 and silicon as SiO2, after adjusting the pH, microporous molecular sieve template agent and polyethyleneimine are added, and after aging and crystallization, intermediate B is obtained; H2: Intermediate B is treated with NH4F solution, then added to β molecular sieve precursor solution, and crystallized at 80-100℃ for 6-12h, then heated to 120-150℃ for 24-48h to obtain intermediate C. The β molecular sieve precursor solution contains 5-15wt% acrylamide by mass of the total mass of the β molecular sieve precursor solution. H3: Intermediate C is placed in a prepolymer solution, impregnated under pressure, and stirred at 65-75°C for at least 4 hours. After filtration and calcination, the reaction monomer A in the prepolymer solution includes at least an unsaturated monomer containing an epoxy group.

[0028] To improve the catalytic effect on plant-based bitumen, this application employs a composite support obtained by combining two types of molecular sieves. This composite support achieves a uniform transition of pores and enhances interfacial bonding, thereby increasing the lifespan and catalytic effect of the composite support, ultimately increasing the content of isomerization products in biofuel and ensuring the freezing point meets standards. However, in conventional physical mixing of molecular sieves, the interfacial interaction between the two types is weak and the pore differences are significant, limiting mass transfer and hindering the synergistic catalytic effect of the two. Therefore, the in-situ co-existing composite method used in this application significantly improves the interfacial bonding and catalytic synergy of the composite support.

[0029] In the preparation of the composite support in this application, the intermediate B synthesized in step H1 is a hierarchical porous SAPO-11 molecular sieve. The addition of polyethyleneimine allows intermediate B to contain polyethyleneimine components. On the one hand, after the addition of the prepolymer in step H3, the amino groups in polyethyleneimine and the epoxy groups in the prepolymer undergo a ring-opening reaction, achieving chemical bonding between intermediate B and the prepolymer. This enhances the interfacial bonding force with the β molecular sieve through the prepolymer, eliminates the interfacial boundary, and avoids the removal of the shell. On the other hand, it can also form a macroporous channel structure during subsequent calcination. The size of this channel structure is larger than the micropores of SAPO-11 and the micropores and mesopores (acrylamide formation) of the β molecular sieve. This allows for a uniform transition from micropores and mesopores to macropores in the composite support, thereby improving the mass transfer efficiency, service life, and catalytic effect of the composite support, and increasing the content of isomerization products and freezing point control.

[0030] In the preparation of the composite carrier in this application, step H2 involves treating intermediate B with NH4F solution. This allows the β-zeolite precursor liquid to achieve directional growth on the surface of intermediate B under the influence of electrostatic adsorption, surface site induction, and lattice compatibility. Consequently, a directional heterogeneous composite structure is formed between SAPO-11 and the β-zeolite, initially eliminating the interface boundary. Furthermore, crystallization at 80-100℃ increases the number of microcrystal nuclei formed on intermediate B, while crystallization at 120-150℃ enables rapid growth of the nuclei along the lowest energy crystal direction, achieving directional alignment. This two-step crystallization process avoids the disordered crystal growth caused by high-temperature rapid crystallization, significantly improving the coverage and orientation of the β-zeolite on the SAPO-11 surface.

[0031] In the preparation of the composite support in this application, the β-zeolite precursor solution in step H2 contains 5-15 wt% acrylamide, which serves several purposes. First, in the alkaline synthesis gel, acrylamide monomers can act as gel stabilizers, increasing the viscosity of the gel, improving its uniformity and stability, and facilitating the formation of a more uniform nucleation environment. Second, during the heating and crystallization process, acrylamide or its oligomers can act as space fillers. Although they do not possess the strong structure-directing properties of classic organic amines, they can physically confine the local growth environment of the zeolite crystals, acting as "soft templates" to form new microporous or mesoporous structures. Third, acrylamide molecules or their polymer chains can act as morphology regulators, adsorbing onto specific crystal faces of the zeolite crystals, changing the growth rate of different crystal faces, thereby effectively controlling the final morphology of the crystals and reducing the grain size. This helps to synthesize nanoscale zeolites, resulting in zeolites with shorter channels and larger specific surface areas, which can significantly improve mass transfer efficiency and exhibit excellent performance in catalytic reactions.

[0032] In the preparation of the composite support in this application, the prepolymer solution is pressurized and impregnated with intermediate C in step H3. This process serves two purposes: First, it allows the prepolymer solution to penetrate to the interface between SAPO-11 molecular sieve and β molecular sieve. The epoxy groups in the prepolymer can undergo ring-opening reactions with the amino groups of polyethyleneimine and acrylamide. Furthermore, acrylamide can continue to polymerize with the prepolymer at 65-75°C to form a polymer, further improving the connectivity between the prepolymer and the shell. This allows for the chemical connection of the two molecular sieves through the prepolymer, eliminating interfacial interactions. Second, the prepolymer can form a cross-linked network structure within intermediate C during the reaction in step H3, which is then burned off during subsequent calcination. This allows for the regulation of the overall pore matching of the composite support, thereby improving the catalytic effect of the catalyst.

[0033] Optionally, the molar ratio of the microporous molecular sieve template agent to the aluminum source in step H1 is (1.0-2.5):1, and the aluminum source is calculated as Al2O3; The molecular weight of polyethyleneimine is 2000, and the mass of polyethyleneimine accounts for 50 wt% of the aluminum source.

[0034] The dosage of the aforementioned microporous molecular sieve template agent and polyethyleneimine can achieve the formation of micropores and macropores in SAPO-11, resulting in pores with a uniform transition between micropores, mesopores and macropores. Furthermore, the dosage of polyethyleneimine can improve the bonding force with the shell layer and eliminate the interface boundary between the two molecular sieves.

[0035] Optionally, the microporous molecular sieve template agent includes one of di-n-propylamine, diisopropylamine, and diethylamine.

[0036] Optionally, the aluminum source in step H1 is one of boehmite, aluminum sulfate, sodium aluminate, and aluminum hydroxide sol; the silicon source is one of silica sol, water glass, and tetraethyl orthosilicate; and the phosphorus source is one of phosphoric acid and ammonium dihydrogen phosphate.

[0037] Optionally, the concentration of the NH4F solution in step H2 is 0.1-0.3 mol / L, the treatment temperature is 60-80℃, and the treatment time is 1-2 h.

[0038] The concentration of the NH4F solution and the parameter settings for the treatment are, firstly, to selectively remove unstable non-framework aluminum from intermediate B, stabilize the framework structure, open blocked micropores and mesopores, increase specific surface area and pore volume, reduce the starting point of framework collapse under hydrothermal conditions, make the molecular sieve more stable, and make the acid site distribution more uniform; secondly, to perform framework dealuminization and silicon replenishment, create a silicon-rich layer, increase the framework silicon-aluminum ratio, enhance hydrophobicity and catalytic stability, make it more stable in reactions involving water, and improve its resistance to carbon deposition.

[0039] Optionally, the β-zeolite precursor solution in step H2 includes a silicon source, an aluminum source, a template agent, and water, wherein the molar ratio of the silicon source, aluminum source, template agent, and water is 1:(0.01-0.05):(0.2-0.6):(15-40), wherein the aluminum source is calculated as Al2O3 and the silicon source is calculated as SiO2.

[0040] The above dosage ensures the directional growth of β-zeolite on SAPO-11, resulting in a shell with high crystallinity and pore structure, thereby improving the catalytic effect.

[0041] Optionally, the silicon source of the β-molecular sieve precursor solution includes silica sol and water glass, and the aluminum source includes sodium aluminate.

[0042] Optionally, the template agent for the β-zeolite precursor solution includes tetraethylammonium hydroxide and tetraethylammonium bromide.

[0043] Both the microporous molecular sieve template agent in step H1 and the template agent in the β-molecular sieve precursor solution contain amino groups. Therefore, the template agent in step H1 and the template agent in the β-molecular sieve precursor solution can also achieve the connection with the epoxy groups in the prepolymer, thereby improving the crosslinking degree of the prepolymer in step H3 reaction, which in turn improves the bonding force between SAPO-11 molecular sieve and β-molecular sieve, and further optimizes the pore structure of intermediate C after calcination to improve the catalytic effect.

[0044] Optionally, the epoxy-containing unsaturated monomer is selected from at least one of glycidyl methacrylate and allyl glycidyl ether.

[0045] Optionally, the prepolymer solution is obtained by polymerizing acrylic acid and an unsaturated monomer containing epoxy groups, and the preparation method of the prepolymer solution is as follows: The unsaturated monomer containing epoxy groups and the acrylic acid are added to a solvent and polymerized for 1-2 hours under the action of an initiator to obtain the prepolymer solution.

[0046] If the prepolymer is obtained by polymerization of pure unsaturated monomers containing epoxy groups, it will have a large number of epoxy groups, resulting in more reaction sites with SAPO-11 and β-zeolites. However, due to steric hindrance, the utilization rate of these epoxy groups cannot be improved, and the interfacial forces between SAPO-11 and β-zeolites cannot be increased further after reaching a certain level. The prepolymer of this application is further obtained by polymerization of acrylic acid and unsaturated monomers containing epoxy groups. The number of epoxy groups in the prepolymer can be controlled by the acrylic acid, achieving uniform dispersion of the epoxy groups and thus improving their utilization rate. This further enhances the interfacial bonding between SAPO-11 and β-zeolites.

[0047] Optionally, the molar ratio of the acrylic acid and the epoxy-containing unsaturated monomer is 1:(0.2-0.4).

[0048] Under the above-mentioned raw material dosage, the interfacial reinforcement effect of the prepolymer on the composite support can be optimized, the composite support has the highest mechanical strength under the test, and the service life of the catalyst is extended.

[0049] Optionally, the oil-soluble catalyst is an ionic liquid catalyst.

[0050] Optionally, the preparation method of the ionic liquid catalyst is as follows: S1: N in a molar ratio of 1:(1-1.2) (2,3-epoxypropyl)phthalimide reacts with phytic acid to give reactant monomer I; S2: Reacting and processing monomer I with haloalkane monomers yields intermediate II, which is then treated with a strongly basic anion exchange resin to obtain intermediate III. S3: Add the metal salt to intermediate III, mix and heat to react, then dry to obtain the final product.

[0051] This application uses N with a molar ratio of 1:(1-1.2). The reaction of (2,3-epoxypropyl)phthalimide with phytic acid yields monomer I, which has a novel structure. The reaction equation is as follows: .

[0052] The obtained monomer I can react with haloalkanes to obtain intermediate II, which is then treated with a strongly basic anion exchange resin and a metal acid salt to obtain the final ionic liquid catalyst. The structure of monomer I can form a steric barrier around the N atom, on the one hand, H under acidic conditions + The difficulty in approaching the N atom reduces the probability of protonation and improves the acid resistance of the ionic liquid catalyst. On the other hand, the phytic acid structure increases the steric hindrance of reactant I, which can hinder the contact between impurity molecules and active sites, reduce impurity adsorption, and thus improve the impurity resistance of the ionic liquid catalyst, making it more suitable for catalyzing plant pitch.

[0053] In addition, the phosphate groups in the phytic acid used in this application form chelates with metal ions, which have a weak binding force with the active sites of the ionic liquid and are prone to desorption during the reaction. Therefore, the ionic liquid catalyst has a "self-cleaning" ability to resist the erosion of impurities.

[0054] Optionally, the reaction temperature in step S1 is 40-50℃, the reaction time is 4-6h, and triethylamine is added at 3-5wt% of the mass of phytic acid.

[0055] The above-mentioned reaction temperature and reaction time can improve the production efficiency of reactant monomer I and reduce production costs.

[0056] Specifically, in step S2 of this application, the haloalkane monomer that reacts with reactant monomer I can be a conventional haloalkane in the prior art, such as an iodoalkane containing 1-14 carbon atoms, a bromoalkane containing 1-14 carbon atoms, or a chloroalkane containing 1-14 carbon atoms.

[0057] Preferably, the haloalkane monomer includes at least one selected from iodomethane, bromooctane, bromodecane, bromododecane, and bromotetradecane.

[0058] Optionally, the haloalkane monomer is obtained by reacting a carboxyl-containing haloalkane with a monohydroxy compound containing a thioether bond.

[0059] Based on the novel tertiary amine structure, the use of the aforementioned haloalkane in the ionic liquid catalyst allows it to possess a side chain containing a sulfide bond. This, on the one hand, promotes uniform charge distribution within the ionic liquid catalyst through electron-donating conjugation, avoiding the influence of acidic H+. + It can target and attack ionic liquids while reducing the adsorption sites of polar impurities (such as metal ions and polar small molecules); on the other hand, it can maintain the dispersion and flowability of ionic liquid catalysts under the influence of their steric hindrance and hydrophobic properties, thus ensuring the stability of catalysis; furthermore, it can improve the integrity and antioxidant properties of the molecular skeleton of ionic liquid catalysts, thereby improving the stability of ionic liquid catalysts in complex environments, and thus improving the yield and quality of jet fuel.

[0060] Optionally, the monohydroxy compound containing a thioether bond includes at least one of ethyl 2-hydroxyethyl thioether (CAS: 110-77-0) and 2-methylthioethanol (CAS: 5271-38-5).

[0061] The selection of the above compounds can improve the reactivity with carboxyl-containing haloalkanes, thereby increasing the yield of haloalkanes and reducing production costs.

[0062] Specifically, the preparation method of the haloalkane monomer is as follows: A carboxyl-containing haloalkane and a thioether-containing monohydroxy compound in a molar ratio of 1:(1.1-1.2) were added to a solvent, concentrated sulfuric acid was added as a catalyst, and the reaction was carried out at 60-70℃ for 4-6 hours to obtain a crude product, which was then filtered, washed and dried to obtain the final product.

[0063] Optionally, the carboxyl-containing haloalkane is selected from at least one of 6-chlorohexanoic acid, 7-chloroheptanoic acid, 8-chlorooctanoic acid, 9-chlorononanoic acid, 10-chlorodecanoic acid, 11-chloro-undecanoic acid, 6-bromohexanoic acid, 7-bromoheptanoic acid, 8-bromooctanoic acid, 9-bromononanoic acid, 10-bromodecanoic acid, and 11-bromo-undecanoic acid.

[0064] Optionally, the metal salt is a trimetallic acid salt, which is selected from at least one of molybdenum nickel cobaltate, molybdenum nickel manganate, and molybdenum nickel zincate; Optionally, the preparation method of the trimetallic acid salt is as follows: Hydrogen peroxide, nickel sulfate, and a third metal sulfate are added to deionized water and then slowly added dropwise to a boiling ammonium molybdate solution. The ammonium molybdate solution is kept boiling during the dropwise addition. After the dropwise addition is complete, boiling is continued for 1-2 hours to obtain the trimetallic acid salt. The third metal sulfate is selected from one of cobalt sulfate, manganese sulfate, or zinc sulfate.

[0065] Optionally, the molar ratio of nickel sulfate to ammonium molybdate is (0.5-0.8):1, the molar ratio of cobalt sulfate, manganese sulfate or zinc sulfate to ammonium molybdate is (0.3-0.4):1, the hydrogen peroxide accounts for 8-10 wt% of the mass of ammonium molybdate, and the concentration of hydrogen peroxide in the hydrogen peroxide is 30 wt%.

[0066] The beneficial effects of this application include, but are not limited to: 1. The method for producing bio-jet fuel using plant pitch according to this application uses plant pitch as raw material and catalytic hydrogenation to obtain bio-jet fuel. By preheating to reduce viscosity and improving the catalyst, the catalytic hydrogenation efficiency and product purity are improved, and the obtained bio-jet fuel can meet the high standards required by the aviation industry for jet fuel.

[0067] 2. The method for producing bio-jet kerosene from plant bitumen according to this application utilizes an oil-soluble catalyst that enables homogeneous catalysis with the raw materials in a suspended bed reactor, without mass transfer limitations. This catalyst directly attacks macromolecules, resists impurity erosion, improves catalyst selectivity and stability, and increases the purity of intermediate product I. The amount of impurities, colloids, and polar groups in intermediate product I after catalysis by the oil-soluble catalyst is significantly reduced, thus lowering the deactivation probability of the hierarchical porous composite molecular sieve catalyst. This is the core chemical step in the conversion of high molecular weight polymeric oils from plant bitumen.

[0068] 3. The method for producing bio-jet kerosene using plant bitumen according to this application employs a multi-level porous composite molecular sieve catalyst. The composite support in this catalyst contains micropores, mesopores, and macropores, forming a multi-level porous composite molecular sieve that improves catalytic efficiency and effect, thereby increasing product yield. After the first physical treatment and the second homogeneous catalysis, the material has been transformed from "bitumen" into "heavy crude oil," but it still contains large-molecule alkanes and cycloalkanes. At this point, it enters a fixed-bed reactor for deep conversion, which is the core of achieving ultra-low freezing point (<-47℃) for bio-jet kerosene.

[0069] 4. According to the method for producing bio-jet fuel using plant pitch according to this application, the two-stage hydrogenation is carried out in a two-stage manner, and the temperature, pressure and hydrogen-to-oil ratio of the second stage (R2) are higher than those of the first stage (R1), which can significantly improve the yield of bio-jet fuel, reduce the production cost of bio-jet fuel, and facilitate industrial promotion. Attached Figure Description

[0070] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a structural diagram of an apparatus for producing bio-jet fuel from plant bitumen, as described in the embodiments and comparative examples of this application.

[0071] List of components and reference numerals: 1. Plant-based asphalt storage tank; 2. First suspended bed reactor; 3. Second suspended bed reactor; 4. Fixed bed reactor; 5. Hydrogen delivery tank; 6. Distillation tower; 7. Bio-jet fuel storage tank. Detailed Implementation

[0072] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0073] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0074] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0075] The oil-soluble catalyst used in Examples 1-9 and Comparative Examples 1-7 of this application is the ionic liquid catalyst 3# of Example 2 in patent CN119680635B.

[0076] In the embodiments and comparative examples of this application, aging refers to placing the material at room temperature and applying pressure during impregnation at a pressure of 0.5 MPa. The molecular weight of the polyethyleneimine is 2000, and the density of the plant pitch is 1.02 g / cm³. 3 It is a semi-solid at room temperature (25°C), with a kinematic viscosity (40°C) of 15000 cSt (centistokes) and an acid value of 10 mg KOH / g.

[0077] The apparatus structure diagrams used in the methods for producing bio-jet fuel from plant bitumen in the following embodiments and comparative examples are shown below. Figure 1 As shown, the plant bitumen raw material is stored in the plant bitumen storage tank 1, which is mixed with the circulating oil flowing out of the first suspended bed reactor 2 and premixed with the hydrogen transported by the hydrogen transport tank 5 to obtain premixed hydrogen raw material. Then, the premixed hydrogen raw material enters the first suspended bed reactor 2, where 400-1000 ppm of oil-soluble catalyst is added for R1 stage hydrogenation. The effluent then enters the second suspended bed reactor 3 for R2 stage hydrogenation to obtain intermediate product I. Intermediate product I flows out to the fixed bed reactor 4 for a second stage hydrogenation reaction to obtain intermediate product II. Finally, intermediate product II is transported to the fractionation tower 6 for fractionation, and the distillate is collected in the bio-jet fuel storage tank 7.

[0078] In the following examples and comparative examples, the method for producing bio-jet fuel using plant pitch is described. In the first suspended bed reactor 2, an oil-soluble catalyst is added once during the first hydrogenation R1 reaction, and in the second suspended bed reactor 3, an oil-soluble catalyst is added again during the first hydrogenation R2 reaction. The dosage of the oil-soluble catalyst is the same in both suspended bed reactors.

[0079] Example 1 This embodiment relates to a method for producing bio-jet fuel using plant bitumen, comprising the following steps: (1) Add circulating oil with a mass of 1 times that of the plant asphalt to the impurity-removed plant asphalt, heat to 120°C while stirring, maintain constant temperature and stir for 60 minutes, and premix hydrogen according to a hydrogen-to-oil ratio of 1000:1 to obtain premixed hydrogen raw material. (2) Add 1000 ppm of oil-soluble catalyst to the premixed hydrogen feedstock, perform R1 first-stage hydrogenation in the first suspended bed reactor, and then send the product to the second suspended bed reactor to add 1000 ppm of oil-soluble catalyst for R2 first-stage hydrogenation to obtain intermediate product I. R1: Reaction temperature 300℃, pressure 4MPa, liquid hourly space velocity 1.5h. -1 The hydrogen-to-oil ratio was 1000:1; R2: the reaction temperature was 340℃, the pressure was 6MPa, and the liquid hourly space velocity was 1.0h. -1 The hydrogen-to-oil ratio is 1400:1.

[0080] (3) Intermediate product I was added to a fixed-bed reactor and subjected to two-stage hydrogenation under the action of a hierarchical porous composite molecular sieve catalyst to obtain intermediate product II. The hierarchical porous composite molecular sieve catalyst included a composite support and an active metal component supported on the composite support. The loading amount of the active metal component was 10 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst. The two-stage hydrogenation reaction temperature was 360 °C, the pressure was 2 MPa, and the liquid hourly space velocity was 0.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is 1000:1; (4) The intermediate product II is fractionated and the fraction collected at 130℃-300℃ is bio-jet fuel.

[0081] The preparation method of the hierarchical porous composite molecular sieve catalyst is as follows: the composite support is immersed in a solution of nickel nitrate hexahydrate, aged for 12 h, dried at 80 °C for 12 h, calcined at 500 °C for 4 h, and reduced at 450 °C for 4 h. The amount of nickel nitrate hexahydrate added is 10 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst, calculated as nickel.

[0082] The preparation method of the composite carrier is as follows: H1: Aluminum, phosphorus, silicon, and water were used as reactants in a molar ratio of 1:0.8:0.1:40, where the aluminum source was calculated as Al2O3, the phosphorus source as P2O5, and the silicon source as SiO2. After adjusting the pH to 5.5, di-n-propylamine, a microporous molecular sieve template agent, and polyethyleneimine were added. After aging for 12 h and crystallizing at 180 °C for 24 h, intermediate B was obtained. The molar ratio of the microporous molecular sieve template agent to the aluminum source (calculated as Al2O3) was 1:1. The mass of polyethyleneimine accounted for 50 wt% of the aluminum source. Boehmite was used as the aluminum source, silica sol as the silicon source, and phosphoric acid as the phosphorus source. H2: Intermediate B was impregnated with 0.1 mol / L NH4F solution and treated at 80℃ for 2 h. After filtration and drying at 80℃ for 6 h, it was added to the β-molecular sieve precursor solution and crystallized at 80℃ for 12 h. Then, the temperature was raised to 120℃ and crystallized for 48 h to obtain intermediate C. The β-molecular sieve precursor solution contained 5 wt% acrylamide in the total mass of the β-molecular sieve precursor solution. The β-molecular sieve precursor solution was composed of silica sol, sodium aluminate, tetraethylammonium hydroxide and water in a molar ratio of 1:0.01:0.2:15. The aluminum source was calculated as Al2O3 and the silicon source was calculated as SiO2. H3: Intermediate C is placed in a prepolymer solution of glycidyl methacrylate and acrylic acid, impregnated under pressure for 30 min, stirred at 65 °C for 6 h, filtered, and calcined at 500 °C for 4 h to obtain the prepolymer solution. The prepolymer solution is obtained by polymerization of acrylic acid and unsaturated monomers containing epoxy groups. The preparation method of the prepolymer solution is as follows: Glycidyl methacrylate and acrylic acid in a molar ratio of 0.4:1 were added to a solvent, and ammonium persulfate, accounting for 1 wt% of the total mass of monomer A, was added as an initiator. Polymerization was carried out at 65°C for 2 hours to obtain the product.

[0083] Example 2 This embodiment relates to a method for producing bio-jet fuel using plant bitumen, comprising the following steps: (1) Add circulating oil with a mass of 10 times that of the plant asphalt to the impurity-removed plant asphalt, heat to 80°C while stirring, maintain constant temperature and stir for 30 minutes, and premix hydrogen gas according to the hydrogen-oil ratio of 800:1 to obtain premixed hydrogen raw material. (2) Add 400 ppm of oil-soluble catalyst to the premixed hydrogen feedstock, and perform R1 stage hydrogenation in the first suspended bed reactor. Then, transfer the product to the second suspended bed reactor, add 400 ppm of oil-soluble catalyst, and perform R2 stage hydrogenation to obtain intermediate product I. R1: reaction temperature is 330℃, pressure is 2 MPa, and liquid hourly space velocity is 1.0 h⁻¹. -1 The hydrogen-to-oil ratio was 1300:1; R2: the reaction temperature was 360℃, the pressure was 5MPa, and the liquid hourly space velocity was 0.5h. -1 The hydrogen-to-oil ratio is 1500:1; (3) Intermediate product I was added to a fixed-bed reactor and subjected to two-stage hydrogenation under the action of a hierarchical porous composite molecular sieve catalyst to obtain intermediate product II. The hierarchical porous composite molecular sieve catalyst includes a composite support and an active metal component supported on the composite support. The loading amount of the active metal component is 25 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst. The two-stage hydrogenation reaction temperature is 300℃, the pressure is 6 MPa, and the liquid hourly space velocity is 1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is 2000:1; (4) The intermediate product II is fractionated and the fraction collected at 130℃-300℃ is bio-jet fuel.

[0084] The preparation method of the hierarchical porous composite molecular sieve catalyst is as follows: the composite support is impregnated in a solution of cobalt nitrate hexahydrate, aged for 12 h, dried at 80 °C for 12 h, calcined at 500 °C for 4 h, and reduced at 450 °C for 4 h. The amount of cobalt nitrate hexahydrate added is 25 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst, calculated as cobalt.

[0085] The preparation method of the composite carrier is as follows: H1: Aluminum, phosphorus, silicon, and water were used as reactants in a molar ratio of 1:1.0:0.6:60, where the aluminum source was calculated as Al2O3, the phosphorus source as P2O5, and the silicon source as SiO2. After adjusting the pH to 5.5, diisopropylamine, a microporous molecular sieve template agent, and polyethyleneimine were added. After aging for 12 h and crystallizing at 180 °C for 24 h, intermediate B was obtained. The molar ratio of the microporous molecular sieve template agent to the aluminum source (calculated as Al2O3) was 2.5:1. The mass of polyethyleneimine accounted for 50 wt% of the aluminum source. Aluminum sulfate was used as the aluminum source, silica sol as the silicon source, and ammonium dihydrogen phosphate as the phosphorus source. H2: Intermediate B was impregnated with 0.3 mol / L NH4F solution, treated at 60℃ for 2 h, filtered, dried at 80℃ for 6 h, and then added to the β molecular sieve precursor solution. It was crystallized at 100℃ for 6 h, and then heated to 150℃ for 24 h to obtain intermediate C. The β molecular sieve precursor solution contained 15 wt% acrylamide in the total mass of the β molecular sieve precursor solution. The β molecular sieve precursor solution was composed of silica sol, sodium aluminate, tetraethylammonium hydroxide and water in a molar ratio of 1:0.05:0.6:40. The aluminum source was calculated as Al2O3 and the silicon source was calculated as SiO2. H3: Intermediate C is placed in a prepolymer solution of allyl glycidyl ether and acrylic acid, impregnated under pressure for 30 min, and then stirred at 75 °C for 4 h. After filtration and calcination at 500 °C for 4 h, the prepolymer solution is obtained. The prepolymer solution is obtained by polymerization of acrylic acid and unsaturated monomers containing epoxy groups. The preparation method of the prepolymer solution is as follows: Allyl glycidyl ether with a molar ratio of 0.2:1 was added to neutralize acrylic acid in a solvent, and ammonium persulfate, accounting for 1 wt% of the total mass of monomer A, was added as an initiator. Polymerization was carried out at 75°C for 1 hour to obtain the product.

[0086] Example 3 This embodiment relates to a method for producing bio-jet fuel using plant bitumen, comprising the following steps: (1) Add circulating oil with a mass of 5 times that of plant asphalt to the impurity-removed plant asphalt, heat to 100°C while stirring, maintain constant temperature and stir for 30 minutes, and premix hydrogen gas according to a hydrogen-to-oil ratio of 1000:1 to obtain premixed hydrogen raw material. (2) Add 800 ppm of oil-soluble catalyst to the premixed hydrogen feedstock, perform R1 first-stage hydrogenation in the first suspended bed reactor, and then send the product to the second suspended bed reactor to add 800 ppm of oil-soluble catalyst for R2 first-stage hydrogenation to obtain intermediate product I. R1: Reaction temperature 330℃, pressure 3MPa, liquid hourly space velocity 1.0h. -1 The hydrogen-to-oil ratio is 1200:1; R2: Reaction temperature 350℃, pressure 5MPa, liquid hourly space velocity 1.0h.-1 The hydrogen-to-oil ratio is 1500:1.

[0087] (3) Intermediate product I was added to a fixed-bed reactor and subjected to two-stage hydrogenation under the action of a hierarchical porous composite molecular sieve catalyst to obtain intermediate product II. The hierarchical porous composite molecular sieve catalyst included a composite support and an active metal component supported on the composite support. The loading amount of the active metal component was 20 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst. The two-stage hydrogenation reaction temperature was 350 °C, the pressure was 4 MPa, and the liquid hourly space velocity was 1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is 1500:1; (4) The intermediate product II is fractionated and the fraction collected at 130℃-300℃ is bio-jet fuel.

[0088] The preparation method of the hierarchical porous composite molecular sieve catalyst is as follows: the composite support is immersed in a solution of nickel nitrate hexahydrate, aged for 12 h, dried at 80 °C for 12 h, calcined at 500 °C for 4 h, and reduced at 450 °C for 4 h. The amount of nickel nitrate hexahydrate added is 20 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst, calculated as nickel.

[0089] The preparation method of the composite carrier is as follows: H1: Aluminum, phosphorus, silicon, and water were used as reactants in a molar ratio of 1:0.9:0.5:50, where the aluminum source was calculated as Al2O3, the phosphorus source as P2O5, and the silicon source as SiO2. After adjusting the pH to 5.5, diethylamine, a microporous molecular sieve template agent, and polyethyleneimine were added. After aging for 12 h and crystallizing at 180 °C for 24 h, intermediate B was obtained. The molar ratio of the microporous molecular sieve template agent to the aluminum source (calculated as Al2O3) was 2:1. The mass of polyethyleneimine accounted for 50 wt% of the aluminum source. Sodium aluminate was used as the aluminum source, silica sol as the silicon source, and ammonium dihydrogen phosphate as the phosphorus source. H2: Intermediate B was impregnated with 0.2 mol / L NH4F solution, treated at 70℃ for 1 h, filtered, dried at 80℃ for 6 h, and then added to the β-molecular sieve precursor solution. It was then crystallized at 90℃ for 10 h, and then heated to 130℃ for 28 h to obtain intermediate C. The β-molecular sieve precursor solution contained 10 wt% acrylamide in the total mass of the β-molecular sieve precursor solution. The β-molecular sieve precursor solution was composed of silica sol, sodium aluminate, tetraethylammonium hydroxide and water in a molar ratio of 1:0.03:0.4:25. H3: Intermediate C is placed in a prepolymer solution of glycidyl methacrylate and acrylic acid, impregnated under pressure for 30 min, stirred at 70 °C for 5 h, filtered, and calcined at 500 °C for 4 h to obtain the prepolymer solution. The prepolymer solution is obtained by polymerization of acrylic acid and unsaturated monomers containing epoxy groups. The preparation method of the prepolymer solution is as follows: Glycidyl methacrylate and acrylic acid in a molar ratio of 0.3:1 were added to a solvent, and ammonium persulfate, accounting for 1 wt% of the total mass of monomer A, was added as an initiator. The mixture was polymerized at 70°C for 1.5 h to obtain the final product.

[0090] Example 4 The difference between this embodiment and Embodiment 3 is that the mass of polyethyleneimine accounts for 80 wt% of the aluminum source.

[0091] Example 5 The difference between this embodiment and Example 3 is that the concentration of the NH4F solution is 0.5 mol / L.

[0092] Example 6 The difference between this embodiment and Embodiment 3 is that no acrylic acid is added in the preparation of the prepolymer solution; that is, only glycidyl methacrylate is used to obtain the prepolymer solution.

[0093] Example 7 The difference between this embodiment and Example 3 is that the molar ratio of glycidyl methacrylate to acrylic acid is 0.1:1.

[0094] Example 8 The difference between this embodiment and Embodiment 3 is that the hydrogenation of R1 is carried out only in the first suspended bed reactor, without the hydrogenation of R2 in the first embodiment.

[0095] Comparative Example 1 The difference between this comparative example and Example 3 is that polyethyleneimine is not added in step (1).

[0096] Comparative Example 2 The difference between this comparative example and Example 3 is that NH4F solution is not used to treat intermediate B in step (2).

[0097] Comparative Example 3 The difference between this comparative example and Example 3 is that the β molecular sieve precursor solution in step (2) does not contain acrylamide.

[0098] Comparative Example 4 The difference between this comparative example and Example 3 is that step (3) is omitted, and the intermediate C is calcined at 500°C for 4 hours to obtain the composite carrier.

[0099] Comparative Example 5 The difference between this comparative example and Example 3 is that glycidyl methacrylate is not added in step (3), that is, only the prepolymer solution obtained by acrylic acid is used.

[0100] Comparative Example 6 The difference between this comparative example and Example 3 is that hydrogen is not pre-mixed in step (1), and the preheated and viscosity-reduced plant asphalt is directly carried out in step (2).

[0101] Test Example 1 Fifty multi-level porous composite molecular sieve catalyst particles prepared in the above embodiments and comparative examples were taken, and pressure was applied along their radial direction using a particle strength tester. The instantaneous maximum force value during crushing was recorded. The average crushing strength of all tested particles was calculated, and the results are shown in Table 1.

[0102] Table 1

[0103] Test Example 2 The bio-jet fuels obtained by the above examples and comparative examples were analyzed using an Agilent 7890A-5975C gas chromatography-mass spectrometry (GC-MS) system with an HP-5-MS column. The isomer selectivity and jet fuel yield were calculated, and the freezing point and thermal oxidation stability of the bio-jet fuels were tested. The test results are shown in Table 2.

[0104] Where isomer selectivity = [(C6-C18) peak area ratio of isomer products / peak area ratio of all products] × 100%, in units of 100%.

[0105] Aviation kerosene yield = [(130℃-300℃) fraction mass / total oil product mass] × liquid phase yield × 100%, in units of 100%.

[0106] Thermal oxidative stability was determined according to national standard GB / T 9169-2023.

[0107] Table 2

[0108] Test Example 3 In each example and comparative example, the same quality of plant pitch was continuously catalytically hydrogenated for 720 h. The decrease rate of isomer selectivity and the decrease rate of jet fuel yield were tested. The hierarchical porous composite molecular sieve catalyst was not replaced in the cyclic experiment of this test example, but the same amount of ionic liquid catalyst was added every 24 h. The test results are shown in Table 3.

[0109] The rate of decrease in heteroselectivity is calculated as follows: [(heterogeneity in the first hour - heterogeneity in the 720th hour) / heterogeneity in the first hour] × 100%, with units of 1.

[0110] Aviation kerosene yield decline rate = [(aviation kerosene yield in hour 1 - aviation kerosene yield in hour 720) / aviation kerosene yield in hour 1] × 100%, unit is .

[0111] Table 3

[0112] As can be seen from the tests in Test Examples 1-3 above, this application utilizes ionic liquid catalysts and hierarchical porous composite molecular sieve catalysts to efficiently catalytically hydrogenate plant bitumen, improve the isomerization selectivity and yield of bio-jet fuel, and lower the freezing point of bio-jet fuel.

[0113] A comparison of Examples 4 and 3 shows that increasing the amount of polyethyleneimine added reduces the average crushing strength of the composite carrier, as well as the isomerization selectivity and jet fuel yield, and also increases the freezing point of biojet fuel.

[0114] A comparison of Examples 5 and 3 shows that changes in the treatment conditions for intermediate B affect the growth of the β-zeolite, leading to a decrease in the average crushing strength of the composite support and ultimately a decrease in the catalytic effect. A comparison of Comparative Example 2 and Example 3 shows that not using NH4F solution to treat intermediate B results in a greater decrease in the average crushing strength of the composite support, and consequently a greater decrease in the catalytic effect.

[0115] According to the comparison of Examples 6, 7 and Example 3, the amount of acrylic acid added in the prepolymer affects the reinforcing effect on the composite carrier interface, directly affects its average crushing strength, and indirectly affects the catalytic hydrogenation effect on plant pitch, resulting in a decrease in isomer selectivity, jet fuel yield, and cycle catalytic stability.

[0116] A comparison of Examples 8 and 3 shows that the ionic liquid catalyst is the same as that in Example 3. When only the R1 stage of hydrogenation is carried out, the isomerization selectivity and jet fuel yield can meet the basic requirements, but still cannot exceed 70%. Using two suspended bed reactors to carry out the two stages of catalysis, R1 and R2 respectively, can further improve the isomerization selectivity and yield of biojet fuel.

[0117] The comparison between Comparative Example 1 and Example 3 shows that the absence of polyethyleneimine reduces the average crushing strength of the composite support, thus proving that the addition of polyethyleneimine can improve the interfacial bonding between the two molecular sieves, thereby improving the catalytic effect and service life of the catalyst.

[0118] The comparison between Comparative Example 3 and Example 3 shows that even without the addition of acrylamide during the formation of the β molecular sieve, the average crushing strength of the composite support is affected. This demonstrates that the addition of acrylamide can improve the interfacial interaction between the two molecular sieves, thereby increasing the service life of the hierarchical porous composite molecular sieve catalyst and its catalytic effect on plant pitch.

[0119] The comparison between Comparative Example 4 and Example 3 shows that if intermediate C is not treated with prepolymer, the interfacial connectivity of the composite carrier is reduced, which in turn reduces the average crushing strength, ultimately leading to a decrease in isomerization selectivity and jet fuel yield.

[0120] The comparison between Comparative Example 5 and Example 3 shows that when the prepolymer does not contain unsaturated monomers with epoxy groups, it cannot form a chemical bond with the two molecular sieves, which leads to a decrease in average crushing strength. As a result, the multi-level porous composite molecular sieve catalyst not only has a shorter service life, but also a lower catalytic effect on plant asphalt.

[0121] According to the comparison between Comparative Example 6 and Example 3, the multi-level porous composite molecular sieve catalyst is the same as that in Example 3. In step (1), hydrogen is not pre-mixed, so the isomer selectivity and jet fuel yield both decrease, and the freezing point of jet fuel also increases. Furthermore, the decrease rate of isomer selectivity and jet fuel yield in Test Example 3 also increases, proving that not pre-adding hydrogen will also affect the cyclic catalyticity of bio-jet fuel.

[0122] Example 9 The difference between this embodiment and Example 3 is that the ionic liquid catalyst prepared by the following method replaces the oil-soluble catalyst in Example 3, as detailed below: S1: Add 0.1 mol of N (2,3-epoxypropyl)phthalimide and 0.1 mol of phytic acid were added to a mixed solvent of ethanol and water (ethanol to water volume ratio of 3:1), followed by the addition of triethylamine at 3 wt% of the phytic acid mass. The mixture was stirred at 40 °C for 6 h, the solvent was removed by filtration and rotary evaporation, and the mixture was extracted three times with a mixed solvent of diethyl ether and water (diethyl ether to water volume ratio of 1:1). The mixture was then dried to obtain reactant monomer I. S2: Dissolve 0.08 mol of reactant monomer I and 0.08 mol of bromooctane in a mixed solvent of ethanol and acetone (volume ratio of ethanol to acetone is 1:1), heat under reflux for 24 h, rotary evaporate, extract three times with a mixed solvent of diethyl ether and acetonitrile (volume ratio of 1:1), and then dry to obtain intermediate II. Dissolve intermediate II in ethanol and add it to an ion exchange column packed with OH- type strong basic anion exchange resin. Elute with ethanol, collect the strong basic eluent with pH>8, and dry at 80℃ for 24 h to obtain intermediate III. S3: 10 wt% hydrogen peroxide (30 wt% hydrogen peroxide concentration), 0.08 mol nickel sulfate, and 0.03 mol manganese sulfate were added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a rate of 1 drop / second, maintaining the ammonium molybdate solution at a boil. After the addition was complete, boiling was continued for 2 hours to obtain the trimetallic acid salt. Intermediate III and the trimetallic acid salt were mixed in a molar ratio of 4:1, stirred at room temperature for 6 hours, then heated to 70°C and reacted for 10 hours. Ethanol and water were then removed by rotary evaporation, and finally the mixture was vacuum dried at 80°C for 24 hours to obtain the ionic liquid catalyst. Example 10 The difference between this embodiment and Example 3 is that the ionic liquid catalyst prepared by the following method replaces the oil-soluble catalyst in Example 3, as detailed below: S1: N2 with a molar ratio of 0.1 mol (2,3-epoxypropyl)phthalimide and 0.12 mol of phytic acid were added to a mixed solvent of ethanol and water (ethanol to water volume ratio of 3:1), followed by the addition of triethylamine at 4 wt% of the phytic acid mass. The mixture was stirred at 40 °C for 5 h, the solvent was removed by filtration and rotary evaporation, and the mixture was extracted three times with a mixed solvent of diethyl ether and water (diethyl ether to water volume ratio of 1:1). The mixture was then dried to obtain reactant monomer I. S2: Dissolve 0.08 mol of reactant monomer I and 0.08 mol of iodomethane in a mixed solvent of ethanol and acetone (volume ratio of ethanol to acetone is 1:1), heat under reflux for 24 h, rotary evaporate, extract three times with a mixed solvent of diethyl ether and acetonitrile (volume ratio of 1:1), and then dry to obtain intermediate II. Dissolve intermediate II in ethanol and add it to an ion exchange column packed with OH- type strong basic anion exchange resin. Elute with ethanol, collect the strong basic eluent with pH>8, and dry at 80℃ for 24 h to obtain intermediate III. S3: 8 wt% hydrogen peroxide (30 wt% hydrogen peroxide concentration), 0.05 mol nickel sulfate, and 0.04 mol zinc sulfate were added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a rate of 2 drops / second. The ammonium molybdate solution was kept boiling during the addition. After the addition was complete, boiling was continued for 1 hour to obtain the trimetallic acid salt. Intermediate III (3:1 molar ratio) and the trimetallic acid salt were mixed, stirred at room temperature for 6 hours, then heated to 60°C and reacted for 12 hours. Ethanol and water were then removed by rotary evaporation, and finally, the mixture was vacuum dried at 80°C for 24 hours to obtain the ionic liquid catalyst. Example 11 The difference between this embodiment and Example 3 is that the ionic liquid catalyst prepared by the following method replaces the oil-soluble catalyst in Example 3, as detailed below: S1: N2 with a molar ratio of 0.1 mol (2,3-epoxypropyl)phthalimide and 0.1 mol of phytic acid were added to a mixed solvent of ethanol and water (volume ratio of ethanol to water: 3:1), followed by the addition of 5 wt% triethylamine. The mixture was stirred at 50 °C for 4 h, filtered, and the solvent was removed by rotary evaporation. The mixture was then extracted three times with a mixed solvent of diethyl ether and water (volume ratio of diethyl ether to water: 1:1) and dried to obtain reactant monomer I. S2: Dissolve 0.08 mol of reactant monomer I and 0.08 mol of bromooctane in a mixed solvent of ethanol and acetone (volume ratio of ethanol to acetone is 1:1), heat under reflux for 24 h, rotary evaporate, extract three times with a mixed solvent of diethyl ether and acetonitrile (volume ratio of 1:1), and then dry to obtain intermediate II. Dissolve intermediate II in ethanol and add it to an ion exchange column packed with OH- type strong basic anion exchange resin. Elute with ethanol, collect the strong basic eluent with pH>8, and dry at 80℃ for 24 h to obtain intermediate III. S3: 10% hydrogen peroxide (30wt% hydrogen peroxide concentration), 0.06 mol nickel sulfate, and 0.04 mol cobalt sulfate were added to deionized water and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a rate of 2 drops / second. The ammonium molybdate solution was kept boiling during the addition. After the addition was completed, the solution was boiled for another 1.5 h to obtain the trimetallic acid salt. Intermediate III and the trimetallic acid salt were mixed in a molar ratio of 4:1 and stirred at room temperature for 6 h. The mixture was then heated to 70 °C and reacted for 10 h. Ethanol and water were removed by rotary evaporation, and the mixture was finally dried under vacuum at 80 °C for 24 h to obtain the ionic liquid catalyst.

[0123] Example 12 The difference between this embodiment and Example 11 is that bromooctane is replaced with a haloalkane obtained by reacting a carboxyl-containing haloalkane with a monohydroxy compound containing a thioether bond. The specific preparation method is as follows: 0.1 mol of 6-chlorohexanoic acid and 0.11 mol of 2-hydroxyethyl sulfide were added to a mixed solvent of dimethylformamide and ethanol (volume ratio of dimethylformamide to ethanol was 1:1). Concentrated sulfuric acid, accounting for 2 wt% of 6-chlorohexanoic acid, was added as a catalyst. The mixture was then reacted at 60 °C for 6 h to obtain a crude product. The product was filtered, washed three times with ethanol, and dried to obtain the final product.

[0124] Example 13 The difference between this embodiment and Example 11 is that bromooctane is replaced with a haloalkane obtained by reacting a carboxyl-containing haloalkane with a monohydroxy compound containing a thioether bond. The specific preparation method is as follows: 0.1 mol of 11-bromo-undecanoic acid and 0.12 mol of 2-methylthioethanol were added to a mixed solvent of dimethylformamide and ethanol (volume ratio of dimethylformamide to ethanol was 1:1). Concentrated sulfuric acid, accounting for 2 wt% of 11-bromo-undecanoic acid, was added as a catalyst. The mixture was then reacted at 70 °C for 4 h to obtain the crude product. The crude product was filtered, washed three times with ethanol, and dried to obtain the final product.

[0125] Example 14 The difference between this embodiment and Embodiment 11 is that molybdate is used instead of trimetallic acid salt.

[0126] Example 15 The difference between this embodiment and Example 11 is that pyridine is used as reactant monomer I.

[0127] Test Example 4 The bio-jet fuel obtained in Examples 10-16 above was tested according to the test method of Test Example 2, and the test results are shown in Table 4.

[0128] Table 4

[0129] Test Example 5 Following the test method of Test Example 3, continuous catalytic hydrogenation was carried out for 720 h using the methods of Examples 10-16. The decrease rate of isomer selectivity and the decrease rate of jet fuel yield were tested. The test results are shown in Table 5.

[0130] The rate of decrease in heteroselectivity is calculated as follows: [(heterogeneity in the first hour - heterogeneity in the 720th hour) / heterogeneity in the first hour] × 100%, with units of 1.

[0131] Aviation kerosene yield decline rate = [(aviation kerosene yield in hour 1 - aviation kerosene yield in hour 720) / aviation kerosene yield in hour 1] × 100%, unit is .

[0132] Table 5

[0133] Based on the test results of Examples 9-11 and Example 3, it can be seen that, on the basis of the hierarchical porous composite molecular sieve catalyst, the use of a novel ionic liquid catalyst can further improve the catalytic effect on plant bitumen, so as to obtain bio-jet fuel with improved isomerization selectivity and yield.

[0134] A comparison of Examples 12 and 13 with Example 11 shows that the side-chain ionic liquid catalyst containing sulfide bonds can further improve the acid degradation resistance and stability of the ionic liquid catalyst under complex environments, thereby improving the yield and quality of jet fuel.

[0135] A comparison of Example 14 and Example 11 shows that the trimetallic salt has better catalytic performance and can further improve isomer selectivity and jet fuel yield.

[0136] A comparison of Examples 15 and 11 shows that conventional pyridine as reactant monomer I has poor catalytic effect on plant pitch, with reduced isomer selectivity and jet fuel yield, and a higher freezing point, proving that the present application utilizes N The reaction monomer I obtained by reacting (2,3-epoxypropyl)phthalimide with phytic acid is more suitable for the hydrogenation catalysis of plant bitumen.

[0137] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for producing bio-jet fuel using plant bitumen, characterized in that, Includes the following steps: (1) The impurity-removed plant asphalt is preheated and viscosity reduced, and hydrogen is premixed according to the hydrogen-to-oil ratio (800-1000):1 to obtain premixed hydrogen raw material; (2) Add an oil-soluble catalyst to the premixed hydrogen feedstock, and after one stage of hydrogenation, obtain intermediate product I; (3) Intermediate product I is added to a fixed-bed reactor and subjected to two-stage hydrogenation under the action of a hierarchical porous composite molecular sieve catalyst to obtain intermediate product II. The hierarchical porous composite molecular sieve catalyst includes a composite support and an active metal component supported on the composite support. The amount of the active metal component added is 10-25 wt% of the total mass of the hierarchical porous composite molecular sieve catalyst, calculated in metal terms. (4) The intermediate product II was fractionated to obtain bio-jet fuel.

2. The method for producing bio-jet kerosene using plant bitumen according to claim 1, characterized in that, The preheating and viscosity reduction temperature of the plant asphalt in step (1) is 80-120℃.

3. The method for producing bio-jet kerosene using plant bitumen according to claim 2, characterized in that, The preheating and viscosity reduction of plant-based asphalt in step (1) specifically involves: Add circulating oil, which is 1-10 times the weight of the plant asphalt, to the purified plant asphalt. While stirring, heat to 80-120℃ and stir for at least 30 minutes after maintaining the temperature.

4. The method for producing bio-jet kerosene using plant bitumen according to claim 1, characterized in that, In step (2), the hydrogenation reaction is carried out at a temperature of 320-360℃, a pressure of 2-6 MPa, and a liquid hourly space velocity of 0.5-1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is (1000-1500):

1.

5. The method for producing bio-jet kerosene using plant bitumen according to claim 1, characterized in that, Step (2) involves a hydrogenation process divided into two stages, specifically: R1: Reaction temperature 340-360℃, pressure 5-6MPa, liquid hourly space velocity 0.5-1.0h. -1 The hydrogen-to-oil ratio is (1400-1500):1, and the amount of oil-soluble catalyst added is 400-1000 ppm; R2: Reaction temperature 300-330℃, pressure 2-4MPa, liquid hourly space velocity 1.0-1.5h. -1 The hydrogen-to-oil ratio is (1000-1300):1, and the amount of oil-soluble catalyst added is 400-1000 ppm.

6. The method for producing bio-jet kerosene using plant bitumen according to claim 1, characterized in that, The second-stage hydrogenation in step (3) is carried out at a reaction temperature of 300-360℃, a pressure of 2-6 MPa, and a liquid hourly space velocity of 0.5-1.5 h⁻¹. - ¹, The hydrogen-to-oil ratio is (1000-2000):

1.

7. The method for producing bio-jet kerosene using plant bitumen according to claim 1, characterized in that, The method for preparing the composite carrier is as follows: H1: Using aluminum, phosphorus, silicon and water as reactants in a molar ratio of 1:(0.8-1.0):(0.1-0.6):(40-60), where aluminum is calculated as Al2O3, phosphorus as P2O5 and silicon as SiO2, after adjusting the pH, microporous molecular sieve template agent and polyethyleneimine are added, and after aging and crystallization, intermediate B is obtained; H2: Intermediate B is treated with NH4F solution, then added to β molecular sieve precursor solution, and crystallized at 80-100℃ for 6-12h, then heated to 120-150℃ for 24-48h to obtain intermediate C. The β molecular sieve precursor solution contains 5-15wt% acrylamide by mass of the total mass of the β molecular sieve precursor solution. H3: Intermediate C is placed in a prepolymer solution, impregnated under pressure, and stirred at 65-75°C for at least 4 hours. After filtration and calcination, the reaction monomer A in the prepolymer solution includes at least an unsaturated monomer containing an epoxy group.

8. The method for producing bio-jet kerosene using plant bitumen according to claim 7, characterized in that, The molar ratio of the microporous molecular sieve template agent to the aluminum source in step H1 is (1.0-2.5):1, and the aluminum source is calculated as Al2O3; The molecular weight of polyethyleneimine is 2000, and the mass of polyethyleneimine accounts for 50 wt% of the aluminum source.

9. The method for producing bio-jet kerosene using plant bitumen according to claim 7, characterized in that, In step H2, the concentration of the NH4F solution is 0.1-0.3 mol / L, the treatment temperature is 60-80℃, and the treatment time is 1-2 h.

10. The method for producing bio-jet kerosene using plant bitumen according to claim 7, characterized in that, The β-zeolite precursor solution in step H2 includes a silicon source, an aluminum source, a template agent, and water. The molar ratio of the silicon source, aluminum source, template agent, and water is 1:(0.01-0.05):(0.2-0.6):(15-40), wherein the aluminum source is calculated as Al2O3 and the silicon source is calculated as SiO2.

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