Hydroisomerization catalyst, method of preparation and use thereof in the production of biodiesel and biojet

Abstract

The present application relates to the technical field of biodiesel and bio-jet fuel, and discloses a hydrogenation isomerization catalyst, a preparation method and application thereof in production of biodiesel and bio-jet fuel. 2 / g~230m 2 / g, the molar ratio of SiO2 / Al2O3 is 30~110, the total acid amount is 0.9mmol(NH3) / g~2.8mmol(NH3) / g, and the acid amount of weak acid and medium-strong acid with NH3 desorption temperature less than 350 DEG C accounts for 70%~90% of the total acid amount of NH3-TPD. The hydrogenation isomerization catalyst prepared by the present application not only has good hydrogenation isomerization performance, but also has good tolerance to oxygen and water carried by reactants.

Description

Technical Field

[0001] This invention relates to the field of biodiesel and biojet fuel preparation technology, specifically to a hydroisomerization catalyst, its preparation method, and its application in the production of biodiesel and biojet fuel. Background Technology

[0002] Biodiesel and biojet fuel are clean, renewable, and green energy sources. Using biodiesel produced from waste oil can reduce greenhouse gas emissions by about 80%. When using fossil jet fuel, carbon dioxide emissions are 88 g / MJ, while when using biojet fuel produced from kitchen waste oil, carbon dioxide emissions are only 14 g / MJ, a reduction of about 84%. Furthermore, biojet fuel produced by this method shows no signs of corrosion to aircraft fuel systems, and long-term storage has no negative impact on fuel quality. When blended with petroleum-based jet fuel at a volume ratio of 1:1, it can reduce fuel consumption by 1%.

[0003] The main component of animal and vegetable oils is fatty acid glycerides, which can be converted into fatty acid methyl esters through transesterification, i.e., first-generation biodiesel. First-generation biodiesel contains unsaturated bonds and oxygen, which significantly affects its stability, calorific value, and viscosity. Fatty acid glycerides, fatty acid ethyl esters, fatty acid methyl esters, and fatty acids in animal and vegetable oils can be converted into bio-based n-alkanes through hydrogenation saturation and hydrodeoxygenation reactions, resulting in second-generation biodiesel. Compared to first-generation biodiesel, second-generation biodiesel has a higher cetane number, is sulfur-free, aromatic-free, and low in oxygen, but its cold filter plugging point (CPP) increases from below 0°C to around 16°C, limiting its application in low-temperature environments. Similarly, jet fuel fraction, a middle distillate of second-generation biodiesel, has a freezing point as high as around 19°C, far exceeding the -40°C requirement.

[0004] Early methods typically employed catalytic dewaxing, using hydrocracking to lower the cold filter plugging point (CPP) of second-generation biodiesel and the freezing point of jet fuel. However, this technique resulted in limited reductions in CPP and freezing point, and low product yields. In recent years, hydroisomerization technology has emerged, addressing the problems inherent in hydrocracking. Compared to hydrocracking, hydroisomerization significantly improves product yield, substantially lowers the CPP of diesel and the freezing point of jet fuel, while maintaining the high cetane number of biodiesel and the high smoke point of biojet fuel.

[0005] The core of hydroisomerization technology is the hydroisomerization catalyst. European patent document EP2600969A4 discloses a catalyst for the hydroisomerization of biodiesel. This catalyst is first shaped by loading an active metal onto a molecular sieve, and then a nickel metal additive is added. Chinese patent document CN103721741A discloses a catalyst for the hydroisomerization of castor oil. This catalyst uses SAPO-34, ZSM-22, and MCM-41 molecular sieves as supports, with Ni and / or Ag as active components and Zn as an additive. Chinese patent document CN108144638A discloses a hydrotreating catalyst for the preparation of jet fuel from microalgae biodiesel. This catalyst uses a Y-type molecular sieve as a support and Ni as the active metal. Chinese patent document CN103920528A discloses a catalyst for the one-step hydrodeoxygenation, cracking, and isomerization of oils to produce jet fuel components. This catalyst uses a Beta molecular sieve as a support and Pd as the active metal. US Patent Document US10479944B2 discloses a hydroisomerization catalyst for the preparation of biojet fuel from castor oil. This catalyst uses NiAPO-11 or NiSAPO-11 as a support and one of Pd, Pt, or Ni as the active metal. Chinese Patent Document CN107488462A discloses a silica-modified mesoporous molecular sieve as a support and Pt or Pd as the active metal.

[0006] The catalysts used in the aforementioned technologies all employ molecular sieves as supports and at least one of Pt, Pd, Ni, and Ag as active components, resulting in good activity and selectivity. However, a shortcoming of these technologies is that they do not address how to improve the catalyst's tolerance to oxygen and water. The hydroisomerization reactants are products of the previous stage of oil hydrodeoxygenation. Residual oxygen in these reactants will generate water through hydrogenation during the hydroisomerization reaction. At high temperatures, this water promotes the aggregation of platinum, palladium, and other metal components on the hydroisomerization catalyst, leading to a reduction in metal active sites. Furthermore, the framework structure and acidity of the molecular sieve are affected by the hydrothermal treatment. While increasing the reaction temperature of the oil hydrodeoxygenation reaction can improve the oxygen removal rate, it also leads to an increase in side reactions such as hydrodecarboxylation, hydrodecarbonylation, and hydrocracking, generating more byproducts such as CO, CO2, gaseous hydrocarbons, and light hydrocarbons, thus reducing the yield of diesel and jet fuel fractions in the oil hydrodeoxygenation stage.

[0007] Therefore, how to develop a catalyst with good hydroisomerization activity, high selectivity and good tolerance to oxygen and water is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] In view of this, the primary technical problem to be solved by the present invention is that existing hydroisomerization catalysts are not resistant to water and oxygen. Therefore, by optimizing and improving the composition of the catalyst, a catalyst support with good resistance to oxygen and water is provided.

[0009] The present invention also provides a hydroisomerization catalyst comprising the above-mentioned catalyst support. This catalyst not only has good hydroisomerization activity and selectivity, and can effectively reduce the cold filter plugging point of biodiesel and the freezing point of biojet fuel, but also has good stability and good tolerance to oxygen and water in bio-based n-alkane reactants.

[0010] Furthermore, the present invention also provides a method for preparing a hydroisomerization catalyst.

[0011] Furthermore, the present invention also provides an application of the above-mentioned hydroisomerization catalyst in the production of biodiesel and biojet fuel. This catalyst enables the long-term stable hydroisomerization reaction of bio-based n-alkanes and can indirectly reduce the harshness of the hydrodeoxygenation reaction conditions of oils and fats, thereby reducing the occurrence of side reactions such as hydrodecarboxylation, hydrodecarbonylation, and hydrocracking.

[0012] The objective of this invention is achieved through the following technical solution:

[0013] According to an embodiment of the present invention, in a first aspect, the present invention provides a catalyst support comprising a modified molecular sieve having a ten-membered ring one-dimensional channel structure with a specific surface area of ​​150 m². 2 / g~230m 2 / g, the SiO2 / Al2O3 molar ratio is 30 to 110, the total acid content is 0.9 mmol (NH3) / g to 2.8 mmol (NH3) / g, and the acid content of weak and moderately strong acids with NH3 desorption temperature below 350℃ accounts for 70% to 90% of the total acid content of NH3-TPD.

[0014] According to an embodiment of the present invention, the specific surface area of ​​the modified molecular sieve is 155 m². 2 / g~218m 2 / g, the SiO2 / Al2O3 molar ratio is 80-100, the total acid content is 1.15mmol(NH3) / g-1.47mmol(NH3) / g, and the acid content of weak and moderately strong acids with NH3 desorption temperature below 350℃ accounts for 72%-89% of the total acid content of NH3-TPD.

[0015] According to an embodiment of the present invention, the modified molecular sieve is formed by sequentially passing a K-type or Na-type molecular sieve through NH4. + It is obtained by exchanging with divalent metal cations.

[0016] According to an embodiment of the present invention, the K-type or Na-type molecular sieve includes at least one of ZSM-12, ZSM-22, ZSM-23, and ZSM-48.

[0017] According to an embodiment of the present invention, the divalent metal cation is selected from Ni. 2+ Cu 2+ Sn 2+ Zn 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ At least one of them.

[0018] According to an embodiment of the present invention, the catalyst support further includes Al2O3, wherein the mass percentage of Al2O3 in the catalyst is 20wt% to 40wt%, the mass percentage of SiO2 is 60wt% to 80wt%, and the mass percentage of the oxide of the divalent metal cation is 0.1wt% to 0.4wt%.

[0019] According to an embodiment of the present invention, in the catalyst, the mass percentage of Al2O3 is 25% to 35%, the mass percentage of SiO2 is 65% to 75%, and the mass percentage of the oxide of the divalent metal cation is 0.1 wt% to 0.3 wt%.

[0020] Secondly, the present invention provides a hydroisomerization catalyst comprising the above-described catalyst support.

[0021] According to embodiments of the present invention, the hydroisomerization catalyst further includes an active metal main agent and a metal auxiliary agent.

[0022] According to an embodiment of the present invention, the content of the active metal main agent is 0.2 wt% to 1.0 wt% based on the mass of the catalyst support, and the content of the metal auxiliary agent is 0.6 wt% to 15 wt%; and / or, the active metal main agent is Pt and / or Pd; and / or, the metal auxiliary agent includes at least one oxide of Mo, Ti, Co, Ni, Sn, and Zr.

[0023] According to an embodiment of the present invention, the content of the active metal main agent is 0.3wt% to 0.7wt% based on the mass of the catalyst support, and the content of the metal auxiliary agent is 1.5wt% to 10wt%.

[0024] Thirdly, the present invention provides a method for preparing the above-mentioned hydroisomerization catalyst, comprising the following steps:

[0025] (1) Mix K-type or Na-type molecular sieves with NH4-containing molecules + The solution undergoes at least one ion exchange, followed by drying and calcination to obtain an H-type molecular sieve; the K-type or Na-type molecular sieve includes at least one of ZSM-12, ZSM-22, ZSM-23, and ZSM-48;

[0026] The H-type molecular sieve is then subjected to at least one ion exchange with divalent metal cations, followed by drying and calcination to obtain a modified molecular sieve.

[0027] The modified molecular sieve is mixed with a binder, an extrusion aid, a peptizing agent, and deionized water, and then extruded into strips to obtain a catalyst support.

[0028] (2) Prepare an aqueous solution containing an active metal precursor and a metal auxiliary precursor to obtain an impregnation solution. Impregnate the catalyst support in the impregnation solution to carry out metal loading, and then dry, calcine and reduce it.

[0029] According to an embodiment of the present invention, in step (1), the K-type or Na-type molecular sieve is subjected to NH4 at 80°C to 90°C. + The H-type molecular sieve is obtained by exchanging the sieve 1 to 4 times, each time for 1 to 8 hours, followed by washing with deionized water 1 to 8 times, drying at 80℃ to 150℃, and calcining at 450℃ to 600℃.

[0030] According to an embodiment of the present invention, in step (1), the H-type molecular sieve is modified by divalent metal cation exchange 1 to 4 times at 80℃ to 90℃, each time for 1 to 8 hours, and then washed with deionized water 1 to 8 times, dried at 80℃ to 150℃, and calcined at 450℃ to 600℃ to obtain the modified molecular sieve.

[0031] According to an embodiment of the present invention, in step (1), the molar concentration of the divalent metal cation is 0.5 mol / L to 2 mol / L.

[0032] According to an embodiment of the present invention, the divalent metal cation includes Ni. 2+ Cu 2+ Sn 2+ Zn 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ At least one of them.

[0033] According to an embodiment of the present invention, the NH4-containing + The molar concentration of the solution is 0.5 mol / L to 2.0 mol / L.

[0034] According to an embodiment of the present invention, the NH4-containing + The solution is an aqueous solution of at least one of NH4NO3, NH4Cl, and CH3COONH4.

[0035] According to an embodiment of the present invention, the mass of the binder is 20 wt% to 50 wt% of the mass of the modified molecular sieve.

[0036] According to an embodiment of the present invention, the binder is high-purity boehmite.

[0037] According to an embodiment of the present invention, the mass of the gel solvent is 3 wt% to 15 wt% of the mass of the modified molecular sieve.

[0038] According to an embodiment of the present invention, the adhesive solvent is at least one selected from nitric acid, citric acid, and acetic acid.

[0039] According to an embodiment of the present invention, the mass of the extrusion aid is 3 wt% to 10 wt% of the mass of the modified molecular sieve.

[0040] According to an embodiment of the present invention, the extrusion aid is guar gum powder.

[0041] According to an embodiment of the present invention, the mass of the deionized water is 40 wt% to 70 wt% of the mass of the modified molecular sieve.

[0042] According to an embodiment of the present invention, the molar concentration of the active metal precursor in the impregnation solution is 0.01 mol / L to 0.08 mol / L.

[0043] According to an embodiment of the present invention, the active metal precursor is at least one of H2PtCl6, (NH4)2PtCl6, Pt(NH3)2Cl2, Pt(NH3)4(CH3COO)2, and PdCl2.

[0044] According to an embodiment of the present invention, the molar concentration of the metal additive precursor in the impregnation solution is 0.1 mol / L to 5 mol / L.

[0045] According to an embodiment of the present invention, the metal additive precursor is (NH4)6Mo7O 24 At least one of Ti(SO4)2, TiCl4, Co(NO3)2, Ni(NO3)2, SnCl2, and Zr(SO4)2.

[0046] According to an embodiment of the present invention, in step (2), the metal is loaded by an equal volume impregnation method, dried at 80°C to 150°C and calcined at 450°C to 600°C, and then reduced at a hydrogen purity greater than 99v%, a hydrogen pressure of 0.1MPa to 14MPa and a reduction temperature of 200°C to 450°C.

[0047] According to an embodiment of the present invention, the mass of the binder is 35 wt% to 45 wt% of the mass of the modified molecular sieve.

[0048] According to an embodiment of the present invention, the mass of the extrusion aid is 6 wt% to 10 wt% of the mass of the modified molecular sieve.

[0049] According to an embodiment of the present invention, the mass of the adhesive solvent is 3 wt% to 5 wt% of the mass of the modified molecular sieve.

[0050] According to an embodiment of the present invention, the mass of the deionized water is 50 wt% to 60 wt% of the mass of the modified molecular sieve.

[0051] According to an embodiment of the present invention, the reduction conditions in step (2) include hydrogen purity ≥ 99.9 v%, hydrogen pressure of 0.1 MPa to 10 MPa, and reduction temperature of 200°C to 400°C.

[0052] Fourthly, the present invention provides an application of the above-mentioned hydroisomerization catalyst in the production of biodiesel and biojet fuel.

[0053] Fifthly, the present invention provides a method for producing biodiesel and biojet fuel, comprising the following steps:

[0054] In the presence of a hydroisomerization catalyst and hydrogen, biodiesel undergoes a hydroisomerization reaction to produce biodiesel and biojet fuel.

[0055] According to an embodiment of the present invention, the biodiesel contains ≤2.0 wt% oxygen and ≤0.5 wt% water.

[0056] According to an embodiment of the present invention, the temperature of the hydroisomerization reaction is 330°C to 400°C, the hydrogen-to-oil volume ratio is 200 NL / L to 1000 NL / L, the hydrogen partial pressure is 3 MPa to 14 MPa, and the liquid hourly space velocity is 0.5 h⁻¹. -1 ~3.0h -1 .

[0057] According to an embodiment of the present invention, the cold filter plugging point of the biodiesel is -25℃ to -29℃; the freezing point of the biojet fuel is -40℃ to -49℃.

[0058] According to an embodiment of the present invention, the temperature of the hydroisomerization reaction is 330°C to 380°C, the hydrogen-to-oil volume ratio is 400 NL / L to 800 NL / L, the hydrogen partial pressure is 4 MPa to 8 MPa, and the liquid hourly space velocity is 1.0 h⁻¹. -1 ~2.5h -1 .

[0059] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0060] 1. The hydroisomerization catalyst provided by this invention first involves reacting a K-type or Na-type molecular sieve with NH4. +The solution undergoes at least one ion exchange to obtain an H-type molecular sieve. Then, the H-type molecular sieve is exchanged with divalent metal cations at least once to convert some of the strong acids in the highly acidic H-type molecular sieve into medium-strong and weak acids. This makes the acidity of the molecular sieve more favorable for hydroisomerization reactions and reduces hydrocracking reactions. Moreover, the divalent metal cations provide more cations for the molecular sieve, which can prevent the molecular sieve from undergoing dealuminization due to hydrothermal action and improve the stability of the molecular sieve framework.

[0061] The hydroisomerization catalyst provided by this invention not only has good hydroisomerization performance, but also has good tolerance to oxygen and water carried by the reactants, ensuring the long-term stable hydroisomerization reaction of biodiesel and biojet fuel.

[0062] 2. The hydroisomerization catalyst provided by the present invention uses Pt and / or Pd as the active metal main agent and at least one of the oxides of Mo, Ti, Co, Ni, Sn, and Zr as the metal auxiliary agent, so that the active metal main agent can be highly dispersed on the support and is not easily aggregated due to the presence of water. Detailed Implementation

[0063] 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.

[0064] 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.

[0065] The specific technical solution of this invention is as follows:

[0066] Molecular sieve synthesis: K-type or Na-type molecular sieves, including at least one of ZSM-12, ZSM-22, ZSM-23, and ZSM-48, are synthesized using a hydrothermal method. The specific preparation method is as follows: Deionized water is mixed evenly with a silicon source, an aluminum source, an inorganic base, and a template agent to form a mixed sol. This sol is then stirred and poured into a stainless steel high-pressure reactor, where it is crystallized at 120℃~180℃ for 24h~100h. After washing, drying, and calcining, the K-type or Na-type molecular sieve is obtained.

[0067] Molecular sieve modification: K-type or Na-type molecular sieves with NH4+-containing... +The solution undergoes ion exchange 1–4 times at 80℃–90℃, each time for 1–8 hours. After washing with deionized water 1–8 times, drying at 80℃–150℃, and calcining at 450℃–600℃, H-type molecular sieve is obtained. The H-type molecular sieve is then subjected to ion exchange with divalent metal cations at 80℃–90℃ 1–4 times, each time for 1–8 hours. After washing with deionized water 1–8 times, drying at 80℃–150℃, and calcining at 450℃–600℃, modified molecular sieve is obtained; wherein the divalent metal cations include Ni. 2+ Cu 2+ Sn 2+ Zn 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ At least one of them.

[0068] Carrier forming: The modified molecular sieve is extruded into strips using a binder, an extrusion aid, a solvent, and deionized water; wherein the binder is high-purity boehmite (SB powder), the extrusion aid is guar gum powder; the solvent is at least one of nitric acid, acetic acid, and citric acid; the amount of binder is 20wt% to 50wt% of the modified molecular sieve, preferably 35wt% to 45wt%; the amount of extrusion aid is 3wt% to 10wt% of the modified molecular sieve, preferably 6wt% to 10wt%; the amount of solvent is 3wt% to 15wt% of the modified molecular sieve, preferably 3wt% to 5wt%; and the amount of deionized water is 40wt% to 70wt% of the modified molecular sieve, preferably 50wt% to 60wt%.

[0069] Active metal loading: An aqueous solution containing an active metal precursor and a metal auxiliary precursor is prepared to obtain an impregnation solution. The catalyst support is then impregnated in the impregnation solution for metal loading. Metal loading is performed using a saturated impregnation method, followed by drying at 80℃~150℃ and calcination at 450℃~600℃. After calcination, both the active metal precursor and the metal auxiliary are in an oxidized state. Reduction treatment is then performed at a hydrogen purity greater than 99v%, a hydrogen pressure of 0.1MPa~14MPa, and a reduction temperature of 200℃~450℃ to obtain a reduced active metal precursor and an oxidized auxiliary. Since the reduction temperature of the active metal precursor Pt and / or Pd is lower than that of the metal auxiliary, a suitable temperature is selected for reduction treatment, allowing the reduced Pt or Pd to be anchored in a highly dispersed form on the oxidized auxiliary clusters, thereby forming highly dispersed and stable reduced active metal precursor clusters on the catalyst surface. The active metal precursor is at least one selected from H2PtCl6, (NH4)2PtCl6, Pt(NH3)2Cl2, Pt(NH3)4(CH3COO)2, and PdCl2; the metal auxiliary precursor is (NH4)6Mo7O. 24 The catalyst contains at least one of Ti(SO4)2, TiCl4, Co(NO3)2, Ni(NO3)2, SnCl2, and Zr(SO4)2; wherein the active metal main agent is present in an amount of 0.2wt% to 1.0wt%, preferably 0.3wt% to 0.7wt%; and the metal auxiliary agent is present in an amount of 0.6wt% to 15wt%, preferably 1.5wt% to 10wt%.

[0070] This invention relates to a hydroisomerization reaction of liquid n-alkanes obtained from the hydrodeoxygenation of oils and fats in the presence of a hydroisomerization catalyst and hydrogen, to prepare low-cooling-filtering-point biodiesel and low-freezing-point biojet fuel. Specifically, the liquid n-alkanes contain ≤2.0% oxygen and ≤0.5 wt% water; the hydrogen partial pressure is 3 MPa–14 MPa, preferably 4 MPa–8 MPa; the reaction temperature is 330℃–400℃, preferably 330℃–380℃; the hydrogen-to-oil volume ratio is 200 NL / L–1000 NL / L, preferably 400 NL / L–800 NL / L; and the liquid hourly space velocity is 0.5 h⁻¹. -1 ~3.0h -1 Preferably 1.0h -1 ~2.5h -1 .

[0071] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0072] Example 1

[0073] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0074] (1) 32.4g KOH, 15.5g Al2(SO4)3·18H2O, 132.6g 1,6-hexanediamine, 382.2g silica sol and 1706.3g deionized water were mixed and stirred evenly to form a sol. The molar ratio of each component to SiO2 was: SiO2 / Al2O3=80, K2O / SiO2=0.5, hexanediamine / SiO2=0.6, H2O / SiO2=50. The sol was transferred to a high-pressure reactor, sealed and stirred continuously. The temperature was raised to 160℃ for crystallization for 72h. After cooling, filtering, washing, drying at 120℃ for 8h and calcining at 550℃ for 8h, KZSM-22 molecular sieve was obtained.

[0075] (2) Weigh 140g of KZSM-22 molecular sieve and place it in 2L of 1mol / L NH4NO3 solution, and perform NH4NO3 reaction at 80℃. + After exchanging for 4 hours, the process was repeated twice. After each exchange, the sample was washed 6 times with deionized water, dried at 120℃ for 8 hours, and calcined at 550℃ for 8 hours to obtain HZSM-22 molecular sieve.

[0076] (3) Take 120g of HZSM-22 molecular sieve and place it in 2L of 1mol / L Cu(NO3)2·3H2O solution, and perform Cu... 2+ The molecular sieve was exchanged for 4 hours and then repeated twice. After each exchange, the molecular sieve was washed 6 times with deionized water, dried at 120℃ for 8 hours, and calcined at 550℃ for 8 hours to obtain CuZSM-22 molecular sieve.

[0077] (4) Weigh 100g CuZSM-22 molecular sieve, 40g SB powder and 7g guar gum powder, mix and grind them thoroughly, add 48g HNO3 solution with a concentration of 10wt% and 55g deionized water, mix evenly and knead, then extrude into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain catalyst support CuZSM-22.

[0078] (5) Prepare 80 mL of H2PtCl6·6H2O aqueous solution containing 0.4 g Pt as impregnation solution. Load Pt onto 100 g CuZSM-22 support using the equal volume impregnation method. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 3 MPa pressure, catalyst Pt / CuZSM-22 is obtained, denoted as catalyst A1. The composition of catalyst A1 is as follows: Pt content is 0.4 wt%, SiO2 content is 71.4 wt%, Al2O3 content is 27.7 wt%, CuO content is 0.22 wt%, and the balance is impurities.

[0079] Example 2

[0080] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0081] (1) The catalyst support CuZSM-22 was prepared using the same method as in Example 1.

[0082] (2) Prepare aqueous solutions of H2PtCl6·6H2O containing 0.4g Pt and (NH4)6Mo7O containing 7.5g MoO3 respectively. 24 40 mL of each of the ·8H2O aqueous solution were mixed thoroughly and used as the impregnation solution. Pt and Mo were loaded onto 100 g of CuZSM-22 support using an equal-volume impregnation method. The mixture was dried at 120 °C for 8 h, calcined at 450 °C for 8 h, and reduced at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 1 MPa pressure to obtain the catalyst Pt-MoO3 / CuZSM-22, denoted as catalyst A2. The composition of catalyst A2 was analyzed to be: Pt content 0.4 wt%, MoO3 content 7.5 wt%, SiO2 content 65.5 wt%, Al2O3 content 26.1 wt%, CuO content 0.22 wt%, with the balance being impurities.

[0083] Example 3

[0084] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0085] (1) The HZSM-22 molecular sieve support was prepared using the same method as in Example 1.

[0086] (2) Weigh 120g of HZSM-22 molecular sieve and place it in 2L of 1mol / L BaCl2·2H2O solution, and perform BaCl2·2H2O reaction at 80℃. 2+ The molecular sieve was exchanged for 8 hours and then repeated once. After each exchange, the molecular sieve was washed 5 times with deionized water, dried at 150℃ for 4 hours, and calcined at 580℃ for 4 hours to obtain BaZSM-22 molecular sieve.

[0087] (3) Weigh 100g of BaZSM-22 molecular sieve, 40g of SB powder and 7g of guar gum powder, mix and grind them thoroughly, add 48g of 10wt% HNO3 solution and 55g of deionized water, mix evenly and knead, then extrude it into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain the catalyst support BaZSM-22.

[0088] (4) Prepare 38 mL each of an aqueous solution of Pt(NH3)4(CH3COO)2 containing 0.4 g Pt and an aqueous solution of Ni(NO3)2·6H2O containing 6.4 g NiO. Mix them thoroughly and use them as impregnation solutions. Pt and Ni are loaded onto 100 g BaZSM-22 support using an equal-volume impregnation method. After drying at 120 °C for 12 h, calcining at 500 °C for 6 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 1 MPa pressure, catalyst Pt-NiO / BaZSM-22 is obtained, denoted as catalyst A3. The composition of catalyst A3 is as follows: Pt content is 0.4 wt%, NiO content is 6.4 wt%, SiO2 content is 66.1 wt%, Al2O3 content is 26.6 wt%, BaO content is 0.20 wt%, and the balance is impurities.

[0089] Example 4

[0090] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0091] (1) Weigh 5.0g sodium hydroxide, 14.5g sodium aluminate, 1197.7g silica sol, 619.5g tetraethylammonium hydroxide and 1565.2g deionized water, mix and stir evenly to form a sol. The molar ratio of each component to SiO2 is: SiO2 / Al2O3=70, Na2O / SiO2=0.02, tetraethylammonium hydroxide / SiO2=0.7, H2O / SiO2=14.6. Transfer the sol to a high-pressure reactor, seal and stir continuously, raise the temperature to 165℃ for crystallization for 100h, cool, filter, wash, dry at 120℃ for 8h, and calcine at 550℃ for 8h to obtain NaZSM-12 molecular sieve.

[0092] (2) Weigh 140g of NaZSM-12 molecular sieve and place it in 2L of 1mol / L NH4Cl solution, and perform NH4Cl incubation at 80℃. + The exchange process was repeated twice over 6 hours. After each exchange, the sample was washed 8 times with deionized water, dried at 80°C for 24 hours, and calcined at 550°C for 6 hours to obtain HZSM-12 molecular sieve.

[0093] (3) Take 120g of HZSM-12 molecular sieve and place it in 2L of 1mol / L CaCl2·2H2O solution, and perform Ca2+ reaction at 90℃. 2+ The molecular sieve was exchanged for 6 hours and repeated 3 times. After each exchange, the molecular sieve was washed 8 times with deionized water, dried at 120℃ for 4 hours, and calcined at 580℃ for 4 hours to obtain CaZSM-12 molecular sieve.

[0094] (4) Weigh 100g CaZSM-12 molecular sieve, 36g SB powder and 8g guar gum powder, mix and grind them thoroughly, add 48g HNO3 solution with a concentration of 10wt% and 55g deionized water, mix evenly and knead, then extrude into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain catalyst support CaZSM-12.

[0095] (5) Prepare 36 mL each of PdCl2 aqueous solution containing 0.6 g Pd and Zr(SO4)2·4H2O aqueous solution containing 4.9 g ZrO2, mix them evenly and use them as impregnation solutions. Pd and Zr are loaded onto 100 g CaZSM-12 support using the equal volume impregnation method. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 8 MPa pressure, catalyst Pd-ZrO2 / CaZSM-12 is obtained, denoted as catalyst A4. The composition of catalyst A4 is as follows: Pd content is 0.5 wt%, ZrO2 content is 4.9 wt%, SiO2 content is 66.9 wt%, Al2O3 content is 27.2 wt%, CaO content is 0.23 wt%, and the balance is impurities.

[0096] Example 5

[0097] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0098] (1) 49.6g NaOH, 25.5g Al2(SO4)3·18H2O, 234.7g dimethylamine, 617.2g silica sol, 49.0g concentrated sulfuric acid (concentration 98%) and 2457.6g deionized water were mixed evenly to form a sol. The molar ratio of each component to SiO2 was: SiO2 / Al2O3=80, Na2O / SiO2=0.8, dimethylamine / SiO2=0.7, H2O / SiO2=44.6. The sol was transferred to a high-pressure reactor, sealed and stirred continuously. The temperature was raised to 175℃ for crystallization for 72h. After cooling, filtering, washing, drying at 120℃ for 8h and calcining at 550℃ for 8h, NaZSM-23 molecular sieve was obtained.

[0099] (2) Weigh 140g of NaZSM-23 molecular sieve and place it in 2L of 1mol / L NH4NO3 solution, and perform NH4NO3 reaction at 90℃. + The molecular sieve HZSM-23 was obtained by exchanging the material for 4 hours and repeating the exchange process 3 times. After each exchange, the material was washed 8 times with deionized water, dried at 120℃ for 10 hours, and calcined at 550℃ for 6 hours.

[0100] (3) Take 120g of HZSM-23 molecular sieve and place it in 2L of 1mol / L ZnCl2 solution, and perform Zn removal at 90℃. 2 + The molecular sieve was exchanged for 4 hours and then repeated twice. After each exchange, the molecular sieve was washed 4 times with deionized water, dried at 120℃ for 4 hours, and calcined at 550℃ for 8 hours to obtain ZnZSM-23 molecular sieve.

[0101] (4) Weigh 100g of ZnZSM-23 molecular sieve, 42g of SB powder and 6g of guar gum powder, mix and grind them thoroughly, add 48g of 10wt% HNO3 solution and 55g of deionized water, mix evenly and knead, then extrude into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain catalyst support ZnZSM-23.

[0102] (5) Prepare 36 mL each of an aqueous solution of Pt(NH3)4(CH3COO)2 containing 0.5 g Pt and an aqueous solution of SnCl2 containing 7.2 g SnO2. Mix them thoroughly and use them as impregnation solutions. Pt and Sn are loaded onto 100 g of ZnZSM-23 catalyst support using an equal-volume impregnation method. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 2 MPa pressure, catalyst Pt-SnO2 / ZnZSM-23 is obtained, denoted as catalyst A5. The composition of catalyst A5 is as follows: Pt content is 0.5 wt%, SnO2 content is 7.2 wt%, SiO2 content is 65.3 wt%, Al2O3 content is 26.4 wt%, ZnO content is 0.22 wt%, and the balance is impurities.

[0103] Example 6

[0104] The method for preparing the hydroisomerization catalyst provided in this embodiment includes the following steps:

[0105] (1) Weigh 354.0g of 1,6-hexanediamine, 18.4g of sodium hydroxide, 30.6g of sodium sulfate octadeca, 924.9g of silica sol and 2455.5g of deionized water, mix them evenly to form a sol, and the molar ratio of each component to SiO2 is: SiO2 / Al2O3=100, Na2O / SiO2=0.2, 1,6-hexanediamine / SiO2=0.7, H2O / SiO2=35; transfer the sol to a high-pressure reactor, seal it and stir continuously, raise the temperature to 165℃ for crystallization for 72h, cool, filter, wash, dry at 120℃ for 8h, and calcine at 550℃ for 8h to obtain NaZSM-48 molecular sieve.

[0106] (2) Weigh 140g of NaZSM-48 molecular sieve and place it in 2L of 1mol / L CH3COONH4 solution, and perform NH4 NH4 ionization at 80℃. + After 4 hours of exchange, the mixture was exchanged once, washed 6 times with deionized water, dried at 120℃ for 8 hours, and calcined at 550℃ for 8 hours to obtain HZSM-48 molecular sieve.

[0107] (3) Take 120g of HZSM-48 molecular sieve and place it in 2L of SnCl2·2H2O solution with a concentration of 1mol / L, and carry out SnCl2·2H2O reaction at 90℃. 2+ The molecular sieve was exchanged for 4 hours and the process was repeated 4 times. After each exchange, the molecular sieve was washed 8 times with deionized water, dried at 100℃ for 16 hours, and calcined at 550℃ for 8 hours to obtain SnZSM-48 molecular sieve.

[0108] (4) Weigh 100g of SnZSM-48 molecular sieve, 35g of SB powder and 10g of guar gum powder, mix and grind them thoroughly, add 48g of 10wt% HNO3 solution and 55g of deionized water, mix evenly and knead, then extrude into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain catalyst support SnZSM-48.

[0109] (5) Prepare 38 mL each of an aqueous solution of H2PtCl6·6H2O containing 0.4 g Pt and an aqueous solution of TiCl4 containing 5.2 g TiO2. Mix them evenly and use them as impregnation solutions. Pt and Ti are loaded onto 100 g SnZSM-48 catalyst support using an equal-volume impregnation method. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and a pressure of 12 MPa, catalyst Pt-TiO2 / SnZSM-48 is obtained, denoted as catalyst A6. The composition of catalyst A6 is as follows: Pt content is 0.4 wt%, TiO2 content is 5.2 wt%, SiO2 content is 66.8 wt%, Al2O3 content is 27.0 wt%, SnO2 content is 0.24 wt%, and the balance is impurities.

[0110] Comparative Example 1

[0111] The preparation method of the hydroisomerization catalyst provided in this comparative example includes the following steps:

[0112] (1) KZSM-22 molecular sieve was prepared using the same method as in Example 1.

[0113] (2) Weigh 100g of KZSM-22 molecular sieve, 40g of SB powder and 7g of guar gum powder, mix and grind them thoroughly, add 48g of 10wt% HNO3 solution and 55g of deionized water, mix evenly and knead, then extrude into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h and calcine at 550℃ for 8h to obtain catalyst support KZSM-22.

[0114] (3) Prepare 80 mL of an aqueous solution of H2PtCl6·6H2O containing 0.4 g Pt as an impregnation solution. Using an equal-volume impregnation method, load Pt onto 100 g of KZSM-22 catalyst support. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and 4 MPa pressure, obtain catalyst Pt / KZSM-22, denoted as catalyst B1. The composition of catalyst B1 is as follows: Pt content 0.4 wt%, SiO2 content 71.8 wt%, Al2O3 content 26.8 wt%, K2O content 0.4 wt%, with the remainder being impurities.

[0115] Comparative Example 2

[0116] (1) HZSM-22 molecular sieve was prepared using the same method as in Example 1.

[0117] (2) Weigh 100.0g of HZSM-22 molecular sieve, 40g of SB powder and 7g of guar gum powder, mix and grind them thoroughly, add 48g of 10wt% HNO3 solution and 55g of deionized water, mix evenly and knead, then extrude it into strips using a clover-shaped mold with a diameter of 1.2mm, dry at 120℃ for 8h, and calcine at 550℃ for 8h to obtain catalyst support HZSM-22.

[0118] (3) Prepare 80 mL of an aqueous solution of H2PtCl6·6H2O containing 0.4 g Pt as the impregnation solution. Load Pt onto 100 g of HZSM-22 support using the equal-volume impregnation method. After drying at 120 °C for 8 h, calcining at 450 °C for 8 h, and reduction at 360 °C for 8 h under an atmosphere of 99.9 wt% hydrogen purity and a pressure of 6 MPa, catalyst Pt / HZSM-22 is obtained, denoted as catalyst B2. The composition of catalyst B2 is as follows: Pt content is 0.4 wt%, SiO2 content is 71.6 wt%, Al2O3 content is 26.9 wt%, and the balance is impurities.

[0119] Comparative Example 3

[0120] The preparation method of the hydroisomerization catalyst provided in this comparative example includes the following steps:

[0121] (1) Weigh 120g of HZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 120 produced by the catalyst factory of Nankai University, place it in 2L of SnCl2·2H2O solution with a concentration of 1mol / L, and carry out SnCl2·2H2O reaction at 80℃. 2+ The molecular sieve was exchanged for 4 hours and then repeated twice. After each exchange, the molecular sieve was washed 6 times with deionized water, dried at 120℃ for 8 hours, and calcined at 550℃ for 8 hours to obtain SnZSM-5 molecular sieve.

[0122] (2) Pt and Ti were impregnated using the same method as in Example 6 to obtain catalyst Pt-TiO2 / SnZSM-5, denoted as catalyst B3. The composition of catalyst B3 was analyzed as follows: Pt content was 0.4 wt%, TiO2 content was 6.2 wt%, SiO2 content was 68.6 wt%, Al2O3 content was 24.0 wt%, SnO2 content was 0.20 wt%, and the balance was impurities.

[0123] Experimental Example 1

[0124] 1. Characterization of physicochemical properties

[0125] The SiO2 / Al2O3 molar ratio, specific surface area, pore volume, total acidity, and the proportion of weak and moderately strong acids were tested for the KZSM-22, HZSM-22, and CuZSM-22 molecular sieves prepared in Example 1, the BaZSM-22 molecular sieve prepared in Example 3, the CaZSM-12 molecular sieve prepared in Example 4, the ZnZSM-23 molecular sieve prepared in Example 5, the SnZSM-48 molecular sieve prepared in Example 6, and the SnZSM-5 molecular sieve prepared in Comparative Example 3. The results are shown in Table 1. SiO2 / Al2O3 was tested using X-ray fluorescence spectrometry. Specific surface area and pore volume were tested using the nitrogen physical adsorption method (BET). Total acid content, weak acid content, and medium-strong acid content were tested using NH3-TPD. The acid content ratio of weak acid and medium-strong acid is the proportion of acid with an NH3 desorption temperature of less than 350℃ to the total acid content. The NH3 desorption temperature range of so-called weak acid is less than 200℃, the NH3 desorption temperature range of so-called medium-strong acid is 200℃ to 350℃, and the NH3 desorption temperature range of so-called strong acid is above 350℃.

[0126] Table 1 Physicochemical properties of molecular sieves

[0127]

[0128] As shown in Table 1, compared to HZSM-22, the SiO2 / Al2O3 ratio of CuZSM-22 and BaZSM-22 remained unchanged, indicating that ion exchange did not cause silicon and aluminum removal. Compared to HZSM-22, the specific surface area and pore volume of CuZSM-22 and BaZSM-22 decreased, indicating that Cu and Ba entered the molecular sieve channels and occupied space. The proportion of weak and medium-strong acids increased in CuZSM-22 and ZnZSM-23. This is because cation exchange converts some of the strong acids in the H-type molecular sieve into medium-strong and weak acids, making the acidity of the molecular sieve more favorable for isomerization reactions and reducing cracking reactions. Similar to CuZSM-22 and BaZSM-22 obtained by molecular sieve modification, the proportion of weak and medium-strong acids in the total acid content of CaZSM-12, ZnZSM-23, and SnZSM-48 obtained after modification all increased to over 70%. As for SnZSM-5, since the original HZSM-5 had a large amount of strong acid, although some of the strong acid was converted into medium-strong acid and weak acid after modification, the proportion of strong acid was still relatively high.

[0129] Experiment Example 2

[0130] 1. Catalyst activity evaluation test

[0131] Using palm oil from Malaysia as raw material, the reaction was carried out under Ni-Mo / γ-Al2O3 hydrodeoxygenation at a reaction pressure of 6 MPa and a liquid hourly space velocity of 2.0 h⁻¹. -1Hydrogenation and deoxygenation reactions were carried out under the process conditions of reaction temperature 320℃ and hydrogen-to-oil volume ratio 1000 NL / L to obtain n-alkanes with physicochemical properties and carbon number distribution as shown in Table 2.

[0132] Table 2 Properties and composition of liquid n-hydrocarbon products from palm oil hydrodeoxygenation

[0133] Analysis Project Analysis results <![CDATA[Density, g / cm 3 > 0.7795 Cold filter plugging point, ℃ 17 Freezing point, °C 19 <![CDATA[Iodine value, gI2 / 100g]]> 1.82 Oxygen content, wt% 1.61 Water content, wt% 0.018 Sulfur content, mg / kg 1.98 Nitrogen content, mg / kg 1.95 Carbon number distribution of liquid hydrocarbons, % <![CDATA[C4~C 14 ]]> 1.64 <![CDATA[C 15 ]]> 18.47 <![CDATA[C 16 ]]> 24.29 <![CDATA[C 17 ]]> 24.48 <![CDATA[C 18 ]]> 31.12

[0134] Sulfur, nitrogen, and other impurity elements have a poisoning effect on hydroisomerization catalysts. Therefore, in the hydrodeoxygenation reaction, the impurity element content should be controlled below 10 mg / kg, preferably below 6 mg / kg, and more preferably below 2 mg / kg. As shown in the table above, the sulfur and nitrogen contents of the n-alkanes prepared from palm oil are relatively low; the oxygen content, which is detrimental to the activity and stability of the hydroisomerization catalyst, is very high, reaching 1.64 wt%; and the cold filter plugging point and freezing point of the n-alkanes are relatively high, at 17℃ and 19℃, respectively. This feedstock oil will be used to investigate the performance of the hydroisomerization catalyst in reducing the cold filter plugging point of diesel fuel and the freezing point of jet fuel, while also examining the effect of its high oxygen content on the stability of the hydroisomerization catalyst.

[0135] 100 mL of the catalysts prepared in each example and comparative example were taken and used as raw materials from the above-mentioned n-carbon products to conduct a comparative evaluation experiment on the activity and stability of the catalysts in a small fixed-bed hydrogenation reaction experimental device. The reaction pressure was 8 MPa and the liquid hourly space velocity was 1 h⁻¹. -1 Under the condition of a hydrogen-to-oil volume ratio of 500 NL / L, low-cold filter plugging point biodiesel and low-freezing-point biojet fuel with qualified physicochemical properties were prepared by adjusting the reaction temperature. The hydroisomerization reaction temperature and evaluation results are shown in Table 3.

[0136] Table 3. Reaction results for each catalyst

[0137]

[0138]

[0139] Table 3 shows that the diesel fuel prepared by catalysts A1–A6 and B1–B2 has a cold filter plugging point (CPP) of -25℃ to -29℃, and the jet fuel has a freezing point of -41℃ to -45℃. The diesel fuel and jet fuel prepared by catalyst B3 have higher CPPs and freezing points. The reaction temperature of catalyst A1 differs by 4℃ between 72h and 960h, and the product yield decreases slightly. This may be because A1 was not impregnated with metal additives, causing the active metal agent to aggregate under the influence of water. The temperature differences between catalysts B1 and B2 at 72h and 960h are significant, at 7℃ and 9℃ respectively. This is because the catalyst activity decreases after 960h of the hydroisomerization reaction, leading to an increase in the cold filter plugging point (CPP) of the prepared diesel and the freezing point of the jet fuel. The reaction temperature needs to be increased to lower the CPP of the diesel and the freezing point of the jet fuel back to the initial reaction levels. With increasing reaction temperature, the liquid yield of B1 and B2 at 72h and 960h decreased by 2.4 and 1.6 percentage points respectively. For B1 and B2, this is because K-type and hydrogen-type molecular sieves have poor hydrothermal stability. When the hydroisomerization reactants contain a certain amount of oxygen, a hydrogenation reaction occurs to generate water. At high temperatures, water promotes the hydrolysis of Si-O-Al bonds, causing aluminum and silicon atoms to be removed from the molecular sieve framework, forming non-framework aluminum and amorphous SiO2. Furthermore, the noble metal main agent aggregates under the influence of water, further deteriorating the stability of the hydroisomerization catalyst. The divalent metal cation exchange improved the hydrothermal stability of the molecular sieve, making the molecular sieve framework more stable. Combined with the metal additives, this helped reduce the aggregation of the precious metal main agent, resulting in a small difference in reaction temperature (0-1℃) between catalysts A2 and A6 at 72h and 960h. Furthermore, the yield, diesel cold filter plugging point (CPP), and jet fuel freezing point also showed minimal changes, indicating good stability of catalysts A2-A6. Catalyst B3, which did not use a one-dimensional molecular sieve, although modified by divalent cation exchange and the addition of metal additives to improve the stability of its precious metal main agent (resulting in minimal changes in reaction temperature, product yield, diesel CPP, and jet fuel freezing point at 72h and 960h), exhibited poor isomerization performance, excessive cracking reactions, low liquid yield, low diesel and jet fuel yields, and a high diesel CPP and freezing point.

[0140] Taking catalyst A2 as an example, the activity of the catalyst under different reaction conditions was investigated, and the results are shown in Table 4.

[0141] Table 4. Reaction results under different conditions

[0142]

[0143] As can be seen from the table above, catalyst A2 exhibits good activity when the reaction temperature reaches above 335℃, and the cold filter plugging point of diesel and the freezing point of jet fuel are both low.

[0144] 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 producing biodiesel and biojet fuel, characterized in that, Includes the following steps: In the presence of a hydroisomerization catalyst and hydrogen, liquid n-alkanes obtained from the hydrodeoxygenation step of oils and fats undergo a hydroisomerization reaction to produce biodiesel and biojet fuel; the liquid n-alkanes have an oxygen content of ≤2.0 wt% and a water content of ≤0.5 wt%. The hydroisomerization catalyst includes a catalyst support; The catalyst support includes a modified molecular sieve having a ten-membered ring one-dimensional channel structure with a specific surface area of ​​150 m². 2 / g~230 m 2 / g, the SiO2 / Al2O3 molar ratio is 30~110, the total acid content is 0.9 mmol(NH3) / g~2.8 mmol(NH3) / g, and the acid content of weak and moderately strong acids with NH3 desorption temperature below 350℃ accounts for 70%~90% of the total acid content of NH3-TPD; The modified molecular sieve is made by sequentially passing K-type or Na-type molecular sieves through NH4+. + Obtained by exchange and divalent metal cation exchange; The K-type or Na-type molecular sieve includes at least one of ZSM-12, ZSM-22, ZSM-23, and ZSM-48; The divalent metal cation is selected from Ni. 2+ Cu 2+ Sn 2+ Zn 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ At least one of them; The hydroisomerization catalyst also includes an active metal main agent and a metal auxiliary agent; Based on the mass of the catalyst support, the content of the active metal agent is 0.2wt%~1.0wt%; the active metal agent is Pt and / or Pd; The catalyst support also includes Al2O3, wherein the mass percentage of Al2O3 in the catalyst is 20wt%~40wt%, the mass percentage of SiO2 is 60wt%~80wt%, and the mass percentage of the oxide of the divalent metal cation is 0.1wt%~0.4wt%.

2. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, The hydroisomerization reaction was carried out at a temperature of 330 °C to 400 °C, with a hydrogen-to-oil volume ratio of 200 NL / L to 1000 NL / L, a hydrogen partial pressure of 3 MPa to 14 MPa, and a liquid hourly space velocity of 0.5 h⁻¹. -1 ~3.0 h -1 ; The biodiesel has a cold filter plugging point of -25 ℃ to -29 ℃; the biojet fuel has a freezing point of -40 ℃ to -49 ℃.

3. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, The hydroisomerization reaction was carried out at a temperature of 330 °C to 380 °C, a hydrogen-to-oil volume ratio of 400 NL / L to 800 NL / L, a hydrogen partial pressure of 4 MPa to 8 MPa, and a liquid hourly space velocity of 1.0 h⁻¹. -1 ~2.5h -1 .

4. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, The modified molecular sieve has a specific surface area of ​​155 m². 2 / g~218 m 2 / g, the SiO2 / Al2O3 molar ratio is 80~100, the total acid content is 1.15 mmol(NH3) / g~1.47 mmol(NH3) / g, and the acid content of weak and moderately strong acids with NH3 desorption temperature below 350 ℃ accounts for 72%~89% of the total acid content of NH3-TPD.

5. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, In the catalyst, the mass percentage of Al2O3 is 25%~35%, the mass percentage of SiO2 is 65%~75%, and the mass percentage of the oxide of divalent metal cation is 0.1wt%~0.3wt%.

6. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, The content of the metal additive is 0.6 wt% to 15 wt% based on the mass of the catalyst support; and / or the metal additive includes at least one oxide of Mo, Ti, Co, Ni, Sn, and Zr.

7. The method for producing biodiesel and biojet fuel according to claim 1 or 6, characterized in that, Based on the mass of the catalyst support, the content of the active metal main agent is 0.3wt%~0.7wt%, and the content of the metal auxiliary agent is 1.5wt%~10wt%.

8. The method for producing biodiesel and biojet fuel according to claim 1, characterized in that, Includes the following steps: (1) Mix K-type or Na-type molecular sieves with NH4-containing molecules + The solution undergoes at least one ion exchange, followed by drying and calcination to obtain an H-type molecular sieve; the K-type or Na-type molecular sieve includes at least one of ZSM-12, ZSM-22, ZSM-23, and ZSM-48; The H-type molecular sieve is then subjected to at least one ion exchange with divalent metal cations, followed by drying and calcination to obtain a modified molecular sieve. The modified molecular sieve is mixed with a binder, an extrusion aid, a peptizing agent, and deionized water, and then extruded into strips to obtain a catalyst support. (2) Prepare an aqueous solution containing an active metal precursor and a metal auxiliary precursor to obtain an impregnation solution. Impregnate the catalyst support in the impregnation solution to carry out metal loading, and then dry, calcine and reduce it.

9. The method for producing biodiesel and biojet fuel according to claim 8, characterized in that, In step (1), the K-type or Na-type molecular sieve is subjected to NH4 at 80 ℃~90 ℃. + The molecular sieve is obtained by exchanging water 1-4 times, each time for 1-8 hours, followed by washing with deionized water 1-8 times, drying at 80-150℃, and calcining at 450-600℃; and / or, The H-type molecular sieve is modified by divalent metal cation exchange at 80 ℃~90 ℃ 1~4 times, each time for 1 h~8 h, followed by washing with deionized water 1~8 times, drying at 80 ℃~150 ℃, and calcining at 450 ℃~600 ℃ to obtain the modified molecular sieve; and / or, The molar concentration of the divalent metal cation is 0.5 mol / L to 2 mol / L; and / or, The divalent metal cation includes Ni. 2+ Cu 2+ Sn 2+ Zn 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ At least one of them; and / or, The NH4-containing + The molar concentration of the solution is 0.5 mol / L to 2.0 mol / L; and / or, The NH4-containing + The solution is an aqueous solution of at least one of NH4NO3, NH4Cl, and CH3COONH4; and / or, The binder has a mass of 20wt% to 50wt% of the modified molecular sieve; and / or, The binder is high-purity boehmite; and / or The mass of the adhesive solvent is 3wt% to 15wt% of the mass of the modified molecular sieve; and / or, The adhesive solvent is at least one of nitric acid, citric acid, and acetic acid; and / or, The mass of the extrusion aid is 3wt% to 10wt% of the mass of the modified molecular sieve; and / or, The extrusion aid is guar gum powder; and / or, The mass of the deionized water is 40wt%~70wt% of the mass of the modified molecular sieve; and / or, In the impregnation solution, the molar concentration of the active metal precursor is 0.01 mol / L to 0.08 mol / L; and / or, The active metal precursor is at least one selected from H2PtCl6, (NH4)2PtCl6, Pt(NH3)2Cl2, Pt(NH3)4(CH3COO)2, and PdCl2; and / or, In the impregnation solution, the molar concentration of the metal auxiliary agent precursor is 0.1 mol / L to 5 mol / L; and / or, The metal additive precursor is (NH4)6Mo7O 24 At least one of Ti(SO4)2, TiCl4, Co(NO3)2, Ni(NO3)2, SnCl2, and Zr(SO4)2; In step (2), the metal is loaded using the equal volume impregnation method. After drying at 80 ℃~150 ℃ and calcining at 450 ℃~600 ℃, the metal is reduced at a hydrogen purity greater than 99v%, a hydrogen pressure of 0.1 MPa~14 MPa and a reduction temperature of 200 ℃~450 ℃.

10. The method for producing biodiesel and biojet fuel according to claim 9, characterized in that, The binder has a mass of 35wt% to 45wt% of the modified molecular sieve; and / or, The mass of the extrusion aid is 6wt% to 10wt% of the mass of the modified molecular sieve; and / or, The mass of the adhesive solvent is 3wt% to 5wt% of the mass of the modified molecular sieve; and / or, The mass of the deionized water is 50wt%~60wt% of the mass of the modified molecular sieve; and / or, The reduction conditions in step (2) include hydrogen purity ≥ 99.9 v%, hydrogen pressure of 0.1 MPa to 10 MPa, and reduction temperature of 200 ℃ to 400 ℃.

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