A molybdenum-based bimetallic catalyst, a preparation method thereof and application thereof in the production of bio-jet fuel by hydrodeoxygenation of fatty acids / esters

Abstract

This invention discloses a Mo-based bimetallic catalyst, its preparation method, and its application in the preparation of bio-jet fuel through the hydrodeoxygenation of fatty acids / esters. The method includes: loading platinum onto a support (a silica-containing material) using an impregnation method; drying the support to obtain a catalyst precursor; mixing the catalyst precursor with a solid molybdenum salt and grinding the mixture to a particle size ≥50 mesh to obtain a mixed powder; calcining the mixed powder in air or an inert gas atmosphere to obtain the Mo-based bimetallic catalyst, wherein the humidity in the air is 5-35% RH, and the calcination temperature is 350-550℃; wherein the mass percentage of platinum in the Mo-based bimetallic catalyst is 1.0%~5.0%, and the mass percentage of molybdenum is 0.4%~8.0%. The Mo-based bimetallic catalyst prepared by this method significantly reduces the reaction temperature, inhibits C-C bond breaking, and reduces carbon loss.

Description

Technical Field

[0001] This invention belongs to the field of deoxygenation and hydrogenation catalysis technology, specifically relating to a Mo-based bimetallic catalyst, its preparation method, and its application in the preparation of bio-jet fuel through fatty acid / ester hydrogenation and deoxygenation. Background Technology

[0002] With the supply of traditional fossil fuels becoming increasingly strained and the pressure to reduce carbon dioxide emissions continuing to grow, the development of renewable and clean alternative energy sources has become a global consensus. Bioenergy, due to its renewable and green nature, has attracted much attention in recent years and is considered one of the ideal ways to solve the global energy crisis. With the ever-increasing demand for biofuels (including biojet fuel and biodiesel), the technology for producing biojet fuel from renewable raw materials is receiving increasing attention.

[0003] Bio-jet fuel is typically produced through the hydrogenation, deoxygenation, and isomerization of animal and vegetable oils. In this process, glycerol is completely hydrogenated to propane, resulting in the loss of oxygen in the molecule as water, leading to significant mass loss and high hydrogen consumption. In contrast, fatty acid / methyl esters are obtained by transesterification / hydrolysis of triglycerides in oils with methanol. This process retains glycerol, reduces mass loss, and yields high-value glycerol.

[0004] In the traditional production of bio-jet kerosene, the hydrogenation stage uses NiMoS catalysts, which require high temperatures (300-450℃) and high pressures (4-15MPa), increasing energy consumption and economic costs. These catalysts are prone to sulfur loss during the reaction, leading to catalyst deactivation and potential product contamination. Therefore, achieving the hydrodeoxygenation of fatty acids / esters to produce bio-jet kerosene under mild conditions remains a challenge in current research, with a focus on the design of highly active catalysts.

[0005] While non-precious metal catalysts (such as Ni, Co, Mo, and Fe) have good industrial application potential, their catalytic activity is relatively low, still requiring high-temperature reaction conditions and increasing energy consumption during the reaction process. Furthermore, the carboxyl groups of fatty acids are highly polar, while the carbon chain skeleton is nonpolar. At high temperatures, the carboxyl groups readily detach from the carbon chain skeleton, producing CO2, resulting in carbon loss and reduced atom utilization, which is detrimental to economic efficiency. For example, the literature "Catal. Sci. Technol., 2019, 9. 3361." discloses that stearic acid undergoes hydrogenation deoxygenation at 300℃ on a NiSn / γ-Al2O3 catalyst, achieving a stearic acid conversion rate exceeding 90%, a heptadecane selectivity as high as 57%, and an octadecane selectivity of less than 5%.

[0006] For example, the literature “ACS Catal. 2021, 11, 7099.” discloses that when methyl laurate is hydrodeoxygenated at 240 °C on a Co / ZrO2 catalyst, the selectivity for undecane reaches 55.2% when the conversion of methyl laurate reaches 100%, while the yield of dodecane is only 16.5%. The literature “Chin. J. Catal. 2023, 47, 229.” discloses that when palmitic acid is hydrodeoxygenated at 270 °C on a Ni / H-CeO2 catalyst, the selectivity for pentadecane reaches 94.8% when the conversion reaches 100%, while the selectivity for hexadecane is less than 5%.

[0007] In patent document CN 116196930 A, researchers doped phosphorus into nickel aluminum oxide to prepare Ni-Al-800-P350. Lauric acid was hydrogenated and deoxygenated on this catalyst at 350°C, and the conversion rate was maintained at about 65%. The selectivity of undecane was as high as 87%, while the selectivity of dodecane was only 5%.

[0008] Therefore, it is essential to efficiently extract oxygen atoms from fatty acids / esters under relatively mild conditions while simultaneously suppressing the breaking of C-C bonds. This relies on the catalyst's ability to efficiently activate both hydrogen and CO bonds. Hydrophilic metals (such as Ir, Pt, Pd, Ru, Rh, etc.) can activate H2 at lower temperatures due to their strong hydrogen dissociation ability. Metal oxides (BO) x Such as MoO x WO x ReO x NbO x Due to its highly efficient ability to activate CO bonds, it is widely used in the hydrogenation and deoxygenation of fatty acids. Numerous studies have shown that it can be used to construct A-BO bonds. x The interface is used to selectively activate fatty acids / esters, and the geometric and electronic structure of the interface is further improved through the carrier effect to enhance the hydrodeoxygenation rate and product selectivity.

[0009] While the introduction of noble metals and metal oxides can lower the reaction temperature to some extent and effectively suppress carboxyl group breakage, maintaining the stability of the carbon skeleton, the reaction temperature typically needs to be above 200℃. This results in a small amount of alkane products with broken C / C bonds, and the selectivity for alkane products without carbon loss rarely reaches 99%. Therefore, developing more efficient catalysts that significantly lower the reaction temperature while increasing alkane yield and suppressing CO2 generation will help promote the high-value utilization of fatty acids / esters, thereby enhancing the economic and environmental benefits of the entire bioenergy industry chain. Summary of the Invention

[0010] In view of the above problems, the present invention provides a method for preparing a Mo-based bimetallic catalyst. The Mo-based bimetallic catalyst prepared by the method of the present invention can significantly reduce the reaction temperature, while reducing carbon loss and improving the quality yield of bio-jet fuel.

[0011] This invention provides a method for preparing a Mo-based bimetallic catalyst, comprising: S1. A hydrophilic metal is loaded onto a support by an impregnation method and dried to obtain a catalyst precursor. The hydrophilic metal is Ir, Pt, Pd, Ru or Rh. S2. Mix the catalyst precursor from step S1 with the solid molybdenum salt and grind it thoroughly to obtain a mixed powder. S3. The mixed powder from step S2 is calcined in air or an inert gas atmosphere to obtain a Mo-based bimetallic catalyst. The humidity in the air range is 5-35%RH, and the calcination temperature is 300-800℃. In the Mo-based bimetallic catalyst, the mass percentage of the hydrophilic metal is 1.0% to 5.0%, and the mass percentage of molybdenum is 0.4% to 8.0%.

[0012] If the particle size of the mixed powder is too large, molybdenum oxide will have difficulty migrating and cannot be dispersed in a low-polymerization manner on the surface of the hydrophilic metal, thus affecting catalytic performance. If the calcination temperature is too low, the migration energy of molybdenum oxide will be insufficient, and it will be unable to migrate to the surface of the hydrophilic metal. If the calcination temperature is too high, the migration will be too vigorous, and the surface of the hydrophilic metal will be completely covered by molybdenum oxide, thus covering the active sites and resulting in poor catalytic performance. Excessive humidity will also affect the migration of molybdenum oxide. In this invention, if the molybdenum content is too high and the hydrophilic metal content is too low, it will easily cover the entire surface, reducing catalytic sites and affecting catalytic performance. If the molybdenum content is too low and the hydrophilic metal content is too high, it will easily cause an insufficient number of bimetallic interfaces, which will also affect catalytic performance.

[0013] Preferably, the carrier comprises one or more of activated carbon, alumina, molecular sieve SBA-15, MCM-41, and silica.

[0014] The present invention provides hydrophilic metal nanoparticles and molybdenum oxide particles based on carrier-stabilized small particles with high specific surface area, thus enabling the generation of a large number of bimetallic interfaces.

[0015] Preferably, the mass percentage of molybdenum in the Mo-based bimetallic catalyst is 1% to 4%. This invention further limits the content of molybdenum, allowing molybdenum oxide to be more uniformly dispersed on the support surface, thereby resulting in a catalyst with higher catalytic performance.

[0016] Preferably, step S1 includes the following steps: The catalyst precursor was prepared by adding the hydrophilic metal precursor solution dropwise to the support and impregnating it for 1-12 hours, followed by drying at 50-120°C for 6-16 hours.

[0017] More preferably, the hydrophilic metal precursor is selected from one or more of chloroiridic acid, iridium chloride, potassium chloroiridate, chloroplatinic acid, platinum nitrate, tetraammineplatinum nitrate, potassium chloroplatinum nitrate, palladium chloride, palladium nitrate, ruthenium chloride, ruthenium acetylacetonate, rhodium chloride, and rhodium acetylacetonate.

[0018] More preferably, the platinum salt is selected from one or more of chloroplatinic acid, tetraammineplatinum nitrate, and platinum nitrate.

[0019] Preferably, the solid molybdenum salt is selected from one or more of ammonium molybdate, sodium molybdate, molybdenum carbide, or molybdenum oxide.

[0020] Preferably, the particle size of the mixed powder is 50-500 mesh.

[0021] Preferably, the grinding is performed by mortar and pestle grinding or dry ball milling.

[0022] Preferably, before calcining the mixed powder, dry air is introduced for air replacement to reduce the relative humidity inside the calcination equipment.

[0023] Preferably, the roasting temperature is 300~800℃ and the roasting time is 1~10h.

[0024] On the other hand, the present invention also provides a method for preparing the Mo-based bimetallic catalyst and a Mo-based bimetallic catalyst.

[0025] On the other hand, the present invention also provides the application of the Mo-based bimetallic catalyst in the catalytic hydrodeoxygenation of fatty acids / esters to prepare biojet fuel.

[0026] Preferably, in the hydrogenation section, the mass ratio of the Mo-based bimetallic catalyst to stearic acid / methyl stearate is 1%–10%, the reaction temperature is 100–200°C, and the hydrogen pressure ranges from 0.5 to 6 MPa; in the isomerization section, the hydrogen partial pressure is 4–10 MPa, the reaction temperature is 200–350°C, and the liquid hourly space velocity is 0.2–3 h⁻¹. -1 The volume ratio of hydrogen to the material entering the reactor is 500–1200.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a high specific surface area support and controls the calcination atmosphere to be either air or an inert gas atmosphere to prevent molybdenum oxide from being reduced to metal monomers, thus enabling molybdenum oxide to sublimate and migrate. Furthermore, this invention controls the particle size of the mixture to prevent excessively large particles from affecting molybdenum oxide migration. It also controls the calcination temperature to regulate the kinetic migration behavior of molybdenum oxide, and controls the content of the hydrophilic metal and metallic molybdenum to prevent molybdenum oxide from completely covering the surface of the hydrophilic metal, thus forming sufficient metal-molybdenum oxide interfaces, generating optimal active sites, and improving catalytic performance. The bimetallic catalyst of this invention can achieve hydrodeoxygenation of fatty acids / esters at lower temperatures, avoiding the high-temperature CC cracking reaction, improving the quality yield of the hydrodeoxygenation stage, and thereby increasing the final yield of bio-jet fuel. Attached Figure Description

[0028] Figure 1 A schematic diagram of a Mo-based bimetallic interface prepared by a process disclosed in the prior art; Figure 2 A schematic diagram of the formation of a Mo-based bimetallic interface provided in a specific embodiment of the present invention; Figure 3 This is a morphology diagram of the Mo-based bimetallic catalyst prepared in Example 1 of the present invention. Detailed Implementation

[0029] The present invention will be further illustrated below through embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] This invention provides a method for preparing a catalyst for the hydrogenation and deoxygenation of fatty acids / esters to produce bio-jet fuel, comprising the following steps: S1. Using the impregnation method, a hydrogen-loving metal is loaded onto a support, and after drying, a catalyst precursor is obtained. S2. The catalyst precursor obtained in step S1 is mixed with solid molybdenum salt and thoroughly ground to obtain a mixed powder. S3. The catalyst powder obtained in step S2 is calcined at high temperature in an air atmosphere with a relative humidity of ≤40%RH to obtain a platinum-molybdenum bimetallic catalyst for the preparation of bio-jet fuel by hydrogenation deoxygenation of glycerol fatty acids / esters. In the bimetallic catalyst, the mass percentage of the hydrophilic metal is 1.0% to 5.0%, and the mass percentage of the molybdenum metal is 0.4% to 8.0%.

[0031] In embodiments of the present invention, the carrier can be self-made or purchased directly.

[0032] In an embodiment of the present invention, in step S1, a hydrophilic metal salt solution is added dropwise to the support for 1-12 hours of impregnation, followed by drying at 50-120°C for 6-16 hours to obtain the catalyst precursor.

[0033] In embodiments of the present invention, the hydrophilic metal precursor is selected from one or more of chloroiridic acid, iridium chloride, potassium chloroiridate, chloroplatinic acid, platinum nitrate, tetraammineplatinum nitrate, potassium chloroplatinate, palladium chloride, palladium nitrate, ruthenium chloride, ruthenium acetylacetonate, rhodium chloride, and rhodium acetylacetonate.

[0034] In an embodiment of the present invention, in step S2, the molybdenum salt is selected from one or more of ammonium molybdate, sodium molybdate, molybdenum carbide, or molybdenum oxide.

[0035] In an embodiment of the present invention, in step S2, the particle size of the mixed powder is 50-500 mesh. The grinding in step S2 can be performed using commonly used grinding methods in the art, such as mortar grinding or dry ball milling.

[0036] In an embodiment of the present invention, in step S3, before calcining the catalyst powder using a calcination device, the air in the calcination device is replaced with air of lower relative humidity to reduce the relative humidity inside the calcination device.

[0037] In an embodiment of the present invention, in step S3, the relative humidity of the air atmosphere in the calcination equipment is 5~35%RH.

[0038] In an embodiment of the present invention, in step S3, the calcination conditions are: 300~800℃ in air atmosphere, calcination for 1~10h.

[0039] The present invention also provides a molybdenum-based bimetallic catalyst prepared according to the above preparation method.

[0040] This invention also provides an application of the above-mentioned Mo-based bimetallic catalyst for catalyzing the hydrodeoxygenation of fatty acids / esters to prepare bio-jet fuel, wherein the fatty acids / esters used are products obtained from the transesterification / hydrolysis of vegetable oils and have a carbon number range of C8 to C18.

[0041] In an embodiment of the present invention, the reaction conditions for the preparation of bio-jet fuel by catalytic hydrodeoxygenation of fatty acids / esters are as follows: in the hydrogenation section, the catalyst accounts for 1% to 10% of the fatty acid mass, the reaction temperature is 100 to 200°C, and the hydrogen pressure range is 0.5 to 6 MPa.

[0042] In the isomerization section, the hydrogen partial pressure is 4–10 MPa, the reaction temperature is 200–350 °C, and the liquid hourly space velocity is 0.2–3 h⁻¹. -1 The volume ratio of hydrogen to the material entering the reactor is 500–1200.

[0043] This invention, based on the thermal dispersion mechanism of molybdenum species on a support surface, aims to construct a Mo-based bimetallic interface with superior hydrodeoxygenation properties. It is generally believed that the spatial structure of metal oxides determines the adsorption configuration and adsorption strength of fatty acids, thus affecting the subsequent CO bond breaking and C / C bond breaking barriers. Literature indicates that when metal oxides are highly dispersed in small clusters on the surface of hydrophilic metals (Ir, Pt, Pd, Ru, and Rh), the catalyst activity is highest, effectively promoting fatty acid hydrodeoxygenation while inhibiting decarboxylation. Therefore, the hydrophilic metal-oligomeric molybdenum cluster interface can be precisely constructed to control the hydrodeoxygenation temperature and optimize product distribution. The commonly used traditional impregnation method is as follows: First, an aqueous solution of a hydrophilic metal salt fills the catalyst pores. After drying, the hydrophilic metal nanoparticles are distributed on the support surface. Then, an aqueous solution of a molybdenum precursor is introduced, and the molybdenum salt ions in the solution randomly fall onto the catalyst surface and the platinum nanoparticle surface. During the subsequent high-temperature oxidizing gas atmosphere roasting process, due to the strong metal-support interaction between the hydrophilic metal and the Mo species under this atmosphere, the molybdenum precursor near the hydrophilic metal nanoparticles gradually grows from the bottom up and encapsulates the platinum nanoparticles. Simultaneously, the molybdenum precursor deposited on the hydrophilic metal nanoparticles also chemically bonds with the hydrophilic metal particles, ultimately forming a tightly contacted hydrophilic metal t@MoO3 interface at the atomic scale (e.g., ...). Figure 1 (As shown).

[0044] However, this process has the following problems: During the impregnation process, the Mo loading needs to be precisely controlled to form a large number of bimetallic interface sites, increasing the probability of Mo species deposition on the hydrophilic metal nanoparticles. If the Mo species loading is insufficient, the number of bimetallic interface sites in the catalyst is small, resulting in low catalytic activity. On the other hand, if the Mo loading is too high, Mo species are prone to spontaneously agglomerate to form high polymers, which will lead to a decrease in interfacial hydrodeoxygenation activity. At the same time, a large amount of Mo deposited on the hydrophilic metal surface will cover the sites, thereby reducing the number of exposed hydrophilic metal sites, thus reducing the catalyst's hydrogenolysis capacity and slowing down the reaction rate. Since the impregnation method achieves spontaneous equilibrium between the solution and the catalyst surface through a certain ion concentration, it is difficult to simultaneously achieve a balance between low-polymerized Mo species and sufficient hydrophilic metal interface sites, thus failing to meet both requirements at the same time.

[0045] In a specific embodiment of the present invention, a hydrophilic metal is first loaded onto a support by impregnation, and after drying, highly dispersed hydrophilic metal particles are obtained. Subsequently, it is physically mixed uniformly with a very small amount of Mo salt. At this point, the hydrophilic metal / support and MoO3 are in a two-phase state, rather than an atomic-scale mixture. Figure 2(a)). During calcination, MoO3 spreads to the catalyst surface through thermal dispersion, i.e., a solid-solid wetting mechanism. During wetting, large MoO3 particles extend to the catalyst surface in the form of MoxOy (x=1~6) with extremely low polymerization degree, forming a thin film. This results in the formation of a very uniform hydrogenophilic metal@MoO3 interface with extremely low Mo polymerization degree. Figure 2 (b) in the middle.

[0046] Therefore, by mixing a very small amount of metallic MoO3, highly efficient low-polymerization MoO3 can be constructed through a "thermal dispersion" method. x The interface is optimized to maximize the number of Pt-Mo interface sites, thereby improving the efficiency of hydrodeoxygenation.

[0047] Based on the significant differences between the above principles and the existing catalyst preparation and application principles, the catalyst preparation process of this invention involves strict control over parameters such as powder particle size and process conditions. This simplifies the preparation process while achieving unexpectedly good catalytic effects. Under the parameter conditions defined in this invention, the prepared catalyst can significantly reduce the hydrodeoxygenation reaction temperature of fatty acids / esters, inhibit the C / C bond breaking reaction during hydrodeoxygenation, and improve the yield of bio-jet fuel.

[0048] The technical solution of the present invention will be further described in detail below with specific embodiments.

[0049] Example 1 Catalyst preparation: Tetraammineplatinum nitrate was dissolved in deionized water. The resulting solution was added dropwise to an activated carbon support, impregnated for 6 hours, and dried in an oven at 60°C for 14 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum oxide powder and ground in a mortar until the powder particles were 50 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 20% RH. The furnace was then calcined at 550°C for 5 hours in an air atmosphere to obtain the target catalyst, a platinum-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0050] Catalytic reaction: Using palm oil hydrolyzed fatty acids as raw material, the catalyst accounted for 3% of the fatty acid mass ratio, the reaction temperature was 130°C, the hydrogen pressure was 3 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 7 MPa, reaction temperature was 280°C, and liquid hourly space velocity was 0.8 h⁻¹. -1 The gas-to-liquid material volume ratio was 500. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2, and the surface morphology of the catalyst is as follows: Figure 3 As shown.

[0051] Example 2 Catalyst preparation: Iridium chloride was dissolved in deionized water, and the resulting solution was added dropwise to a silica support. The solution was impregnated for 10 hours and then dried in an oven at 80°C for 12 hours to obtain the catalyst precursor. The catalyst precursor was mixed with sodium molybdate powder and ball-milled until the powder particles were 150 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged with pure air at a relative humidity of 15% RH. The furnace was then calcined at 350°C for 7 hours in an air atmosphere to obtain the target catalyst, an iridium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0052] Catalytic reaction: Using peanut oil hydrolyzed fatty acids as raw material, the catalyst accounted for 6% of the fatty acid mass ratio, the reaction temperature was 100°C, the hydrogen pressure was 5 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 9 MPa, reaction temperature was 230°C, and liquid hourly space velocity was 0.6 h⁻¹. -1 The gas-to-liquid material volume ratio was 700. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0053] Example 3 Catalyst preparation: Palladium nitrate was dissolved in deionized water, and the resulting solution was added dropwise to an MCM-41 support. The solution was impregnated for 12 hours and then dried in an oven at 50°C for 16 hours to obtain the catalyst precursor. The catalyst precursor was mixed with ammonium molybdate powder and ball-milled until the powder particles were 350 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 30% RH. The furnace was then calcined at 400°C for 4 hours in an air atmosphere to obtain the target palladium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0054] Catalytic reaction: Using fatty acids from soybean oil hydrolysis as raw material, the catalyst accounts for 9% of the fatty acid mass ratio, the reaction temperature is 150°C, the hydrogen pressure is 5 MPa, and the reaction time is 6 h. Isomerization section: Hydrogen pressure is 6 MPa, reaction temperature is 270°C, and liquid hourly space velocity is 1.2 h⁻¹. -1 The gas-to-liquid material volume ratio was 1:100. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0055] Example 4 Catalyst preparation: Ruthenium chloride was dissolved in deionized water, and the resulting solution was added dropwise to an SBA-15 support. After impregnation for 3 hours, the solution was dried in an oven at 90°C for 8 hours to obtain a catalyst precursor. The catalyst precursor was mixed with ammonium molybdate powder and ground in a mortar until the powder particles were 500 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the catalyst raw powder. The obtained catalyst raw powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 35%RH. The furnace was then calcined at 450°C for 9 hours in an air atmosphere to obtain the target catalyst, a ruthenium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0056] Catalytic reaction: Using fatty acids from cottonseed oil hydrolysis as raw material, the catalyst accounted for 2% of the fatty acid mass ratio, the reaction temperature was 160°C, the hydrogen pressure was 1 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 8 MPa, the reaction temperature was 210°C, and the liquid hourly space velocity was 1.6 h⁻¹. -1 The gas-to-liquid material volume ratio was 900. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0057] Example 5 Catalyst preparation: Rhodium acetylacetone was dissolved in deionized water, and the resulting solution was added dropwise to an alumina support. After impregnation for 1 hour, the solution was dried in an oven at 70°C for 10 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum oxide powder and ball-milled until the powder particles were 200 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 10% RH. The furnace was then calcined at 650°C for 2 hours in an air atmosphere to obtain the target catalyst, a rhodium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0058] Catalytic reaction: Using fatty acids from palm kernel oil hydrolysis as raw material, the catalyst accounted for 4% of the fatty acid mass ratio, the reaction temperature was 170°C, the hydrogen pressure was 4 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 4 MPa, reaction temperature was 200°C, and liquid hourly space velocity was 2.4 h⁻¹. -1 The gas-to-liquid material volume ratio was 600. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0059] Example 6 Catalyst preparation: Chloroplatinic acid was dissolved in deionized water, and the resulting solution was added dropwise to a silica support. The solution was impregnated for 7 hours and then dried in an oven at 110°C for 6 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum carbide powder and ball-milled until the powder particles were 400 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 5% RH. The furnace was then calcined at 450°C for 8 hours in an air atmosphere to obtain the target platinum-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0060] Catalytic reaction: Using fatty acid esters from palm oil transesterification as raw material, the catalyst accounts for 8% of the fatty acid ester mass ratio, the reaction temperature is 120°C, the hydrogen pressure is 3 MPa, and the reaction time is 6 h. Isomerization section: Hydrogen pressure is 5 MPa, reaction temperature is 300°C, and liquid hourly space velocity is 1.1 h⁻¹. -1 The gas-to-liquid material volume ratio was 1000. The results of the hydrodeoxygenation and isomerization processes for fatty acid esters are shown in Table 2.

[0061] Example 7 Catalyst preparation: Platinum nitrate was dissolved in deionized water, and the resulting solution was added dropwise to an MCM-41 support. After impregnation for 9 hours, the solution was dried in an oven at 100°C for 7 hours to obtain a catalyst precursor. The catalyst precursor was mixed with sodium molybdate powder and ground in a mortar until the powder particles were 300 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 15%RH. The furnace was then calcined at 500°C for 10 hours in an air atmosphere to obtain the target catalyst, a platinum-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0062] Catalytic reaction: Using fatty acid esters from peanut oil transesterification as raw material, the catalyst accounted for 5% of the fatty acid ester mass ratio, the reaction temperature was 150°C, the hydrogen pressure was 6 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 5 MPa, reaction temperature was 340°C, and liquid hourly space velocity was 2.7 h⁻¹. -1 The gas-to-liquid material volume ratio was 800. The results of the hydrodeoxygenation and isomerization processes for fatty acid esters are shown in Table 2.

[0063] Example 8 Catalyst preparation: Palladium chloride was dissolved in deionized water, and the resulting solution was added dropwise to an alumina support. After impregnation for 5 hours, the solution was dried in an oven at 90°C for 9 hours to obtain a catalyst precursor. The catalyst precursor was mixed with sodium molybdate powder and ball-milled until the powder particles were 350 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 30% RH. The furnace was then calcined at 800°C for 2 hours in an air atmosphere to obtain the target catalyst, a palladium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0064] Catalytic reaction: Using fatty acid esters from soybean oil transesterification as raw material, the catalyst accounted for 6% of the fatty acid ester mass ratio, the reaction temperature was 200°C, the hydrogen pressure was 4 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 10 MPa, reaction temperature was 240°C, and liquid hourly space velocity was 1.9 h⁻¹. -1 The gas-to-liquid material volume ratio was 600. The results of the hydrodeoxygenation and isomerization processes for fatty acid esters are shown in Table 2.

[0065] Example 9 Catalyst preparation: Palladium nitrate was dissolved in deionized water, and the resulting solution was added dropwise to an MCM-41 support. After impregnation for 4 hours, the solution was dried in an oven at 90°C for 11 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum oxide powder and ball-milled until the powder particles were 100 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 10% RH. The furnace was then calcined at 600°C for 1 hour in an air atmosphere to obtain the target catalyst, a palladium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0066] Catalytic reaction: Using fatty acid esters from cottonseed oil transesterification as raw material, the catalyst accounted for 7% of the fatty acid ester mass ratio, the reaction temperature was 170°C, the hydrogen pressure was 3 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 5 MPa, reaction temperature was 220°C, and liquid hourly space velocity was 2.3 h⁻¹. -1 The gas-to-liquid material volume ratio was 1200. The results of the hydrodeoxygenation and isomerization processes of fatty acid esters are shown in Table 2.

[0067] Example 10 Catalyst preparation: Ruthenium acetylacetone was dissolved in deionized water, and the resulting solution was added dropwise to a silica support. After impregnation for 2 hours, the solution was dried in an oven at 120°C for 7 hours to obtain a catalyst precursor. The catalyst precursor was mixed with sodium molybdate powder and ground in a mortar until the powder particles were 200 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 15% RH. The furnace was then calcined at 700°C for 4 hours in an air atmosphere to obtain the target catalyst, a ruthenium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0068] Catalytic reaction: Using fatty acid esters from coconut oil transesterification as raw material, the catalyst accounted for 2% of the fatty acid ester mass ratio, the reaction temperature was 140°C, the hydrogen pressure was 1 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 9 MPa, reaction temperature was 320°C, and liquid hourly space velocity was 0.2 h⁻¹. -1 The gas-to-liquid material volume ratio was 600. The results of the hydrodeoxygenation and isomerization processes for fatty acid esters are shown in Table 2.

[0069] Example 11 Catalyst preparation: Ruthenium chloride was dissolved in deionized water, and the resulting solution was added dropwise to an activated carbon support. The solution was impregnated for 8 hours and then dried in an oven at 80°C for 13 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum carbide powder and ball-milled until the powder particles were 50 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 20% RH. The furnace was then calcined at 550°C for 6 hours in an air atmosphere to obtain the target catalyst, a ruthenium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0070] Catalytic reaction: Using fatty acids from coconut oil hydrolysis as raw material, the catalyst accounts for 5% of the fatty acid mass ratio, the reaction temperature is 190°C, the hydrogen pressure is 3 MPa, and the reaction time is 6 h. Isomerization section: Hydrogen pressure is 7 MPa, reaction temperature is 350°C, and liquid hourly space velocity is 0.9 h⁻¹. -1 The gas-to-liquid material volume ratio was 900. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0071] Example 12 Catalyst preparation: Rhodium chloride was dissolved in deionized water, and the resulting solution was added dropwise to an alumina support. After impregnation for 3 hours, the solution was dried in an oven at 90°C for 15 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum oxide powder and ball-milled until the powder particles were 400 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged and replaced with pure air at a relative humidity of 35%RH. The furnace was then calcined at 750°C for 8 hours in an air atmosphere to obtain the target catalyst, a rhodium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0072] Catalytic reaction: Using fatty acids from tung oil hydrolysis as raw material, the catalyst accounted for 10% of the fatty acid mass ratio, the reaction temperature was 150°C, the hydrogen pressure was 2 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 4 MPa, reaction temperature was 250°C, and liquid hourly space velocity was 0.5 h⁻¹. -1 The gas-to-liquid material volume ratio was 1000. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0073] Example 13 Catalyst preparation: Iridic acid was dissolved in deionized water, and the resulting solution was added dropwise to an alumina support. The solution was impregnated for 6 hours and then dried in an oven at 110°C for 8 hours to obtain the catalyst precursor. The catalyst precursor was mixed with ammonium molybdate powder and ground in a mortar until the powder particles were 250 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged with pure air at a relative humidity of 10% RH. The furnace was then calcined at 400°C for 6 hours in an air atmosphere to obtain the target catalyst, an iridium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0074] Catalytic reaction: Using fatty acids from castor oil hydrolysis as raw material, the catalyst accounted for 6% of the fatty acid mass ratio, the reaction temperature was 140°C, the hydrogen pressure was 6 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 7 MPa, reaction temperature was 300°C, and liquid hourly space velocity was 1.0 h⁻¹. -1 The gas-to-liquid material volume ratio was 800. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0075] Example 14 Catalyst preparation: Potassium chloroiridate was dissolved in deionized water, and the resulting solution was added dropwise to an activated carbon support. The solution was impregnated for 5 hours and then dried in an oven at 50°C for 11 hours to obtain a catalyst precursor. The catalyst precursor was mixed with molybdenum carbide powder and ground in a mortar until the powder particles were 350 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged with pure air at a relative humidity of 20% RH. The furnace was then calcined at 500°C for 5 hours in an air atmosphere to obtain the target catalyst, an iridium-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0076] Catalytic reaction: Using fatty acids from palm oil hydrolysis as raw material, the catalyst accounted for 1% of the fatty acid mass ratio, the reaction temperature was 180°C, the hydrogen pressure was 0.5 MPa, and the reaction time was 6 h. Isomerization section: Hydrogen pressure was 6 MPa, reaction temperature was 260°C, and liquid hourly space velocity was 2.7 h⁻¹. -1 The gas-to-liquid material volume ratio was 1:100. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0077] Example 15 Catalyst preparation: Potassium chloroplatinate was dissolved in deionized water, and the resulting solution was added dropwise to an SBA-15 support. The solution was impregnated for 7 hours and then dried in an oven at 70°C for 6 hours to obtain the catalyst precursor. The catalyst precursor was mixed with ammonium molybdate powder and ground in a mortar until the powder particles were 350 mesh. The powder was then dried in an oven at 120°C for 6 hours to obtain the original catalyst powder. The obtained original catalyst powder was then placed in a muffle furnace, and the air in the muffle furnace was purged with pure air at a relative humidity of 20% RH. The furnace was then calcined at 300°C for 2 hours in an air atmosphere to obtain the target platinum-molybdenum bimetallic catalyst. The metal and molybdenum contents of the catalyst are shown in Table 1.

[0078] Catalytic reaction: Using fatty acids from soybean oil hydrolysis as raw material, the catalyst accounts for 8% of the fatty acid mass ratio, the reaction temperature is 200°C, the hydrogen pressure is 2 MPa, and the reaction time is 6 h. Isomerization section: Hydrogen pressure is 9 MPa, reaction temperature is 290°C, and liquid hourly space velocity is 3 h⁻¹. -1 The gas-to-liquid material volume ratio was 700. The results of the fatty acid hydrodeoxygenation and isomerization processes are shown in Table 2.

[0079] Comparative Example 1 Compared to Example 1, nickel molybdenum sulfide, a catalyst commonly used in the art, was selected as the catalyst for the hydrodeoxidation section, and the hydrogenation reaction was carried out under industry-standard reaction conditions: a hydrogenation reaction temperature of 330°C, a hydrogen pressure of 5 MPa, and a liquid hourly space velocity of 1.5 h⁻¹. -1The isomerization section was carried out under the same reaction conditions as in Example 1, and the catalytic reaction results are shown in Table 2.

[0080] Comparative Example 2 Compared to Example 2, cobalt molybdenum sulfide, a catalyst commonly used in the art, was selected as the catalyst for the hydrodeoxygenation stage, and the hydrogenation reaction was carried out under industry-standard reaction conditions: a hydrogenation reaction temperature of 320°C, a hydrogen pressure of 6 MPa, and a liquid hourly space velocity of 1.2 h⁻¹. -1 The isomerization section was carried out under the same reaction conditions as in Example 2, and the catalytic reaction results are shown in Table 2.

[0081] Comparative Example 3 Compared to Example 3, molybdenum sulfide, a commonly used catalyst in the art, was selected as the catalyst for the hydrodeoxygenation stage, and the hydrogenation reaction was carried out under industry-standard reaction conditions: a hydrogenation reaction temperature of 340°C, a hydrogen pressure of 7 MPa, and a liquid hourly space velocity of 1.2 h⁻¹. -1 The isomerization section was carried out under the same reaction conditions as in Example 3, and the catalytic reaction results are shown in Table 2.

[0082] Comparative Example 4 Compared to Example 4, Raney nickel, a commonly used catalyst, was selected as the catalyst for the hydrodeoxygenation section. The hydrogenation reaction temperature was 280°C, the hydrogen pressure was 4 MPa, and the liquid hourly space velocity was 2 h⁻¹. -1 The isomerization section was carried out under the same reaction conditions as in Example 4, and the catalytic reaction results are shown in Table 1.

[0083] Comparative Example 5 Compared to Example 6, nickel molybdenum sulfide, a catalyst commonly used in the art, was selected as the catalyst for the hydrodeoxygenation stage. The feedstock was fatty acid esters obtained from palm oil transesterification, and the hydrogenation reaction was carried out under industry-standard reaction conditions: a hydrogenation reaction temperature of 335°C, a hydrogen pressure of 5 MPa, and a liquid hourly space velocity of 1.5 h⁻¹. -1 The isomerization section was conducted under the same reaction conditions as in Example 6. The reaction products were analyzed, and the catalytic reaction results are shown in Table 1.

[0084] Table 1 Metal content of molybdenum-based catalysts Table 2. Reaction results of the examples and comparative examples Based on the reaction results of the examples and comparative examples provided in Table 2 above, it can be found that the technical solution of the present invention can significantly improve the activity of fatty acid / ester hydrodeoxygenation catalyst by physically mixing molybdenum salt with a hydrophilic metal, and obtain high alkane yield and bio-jet fuel yield at a reaction temperature of 100-200℃, effectively avoiding the loss of C atoms caused by fatty acid decarboxylation / decarbonylation; while using catalysts commonly used in the art, the alkane product in the hydrodeoxygenation stage suffers a mass loss of 5-14 wt%, resulting in a relatively low bio-jet fuel yield.

[0085] The technical solution of this invention obtains a highly efficient molybdenum-based bimetallic catalyst by controlling the particle size of the mixed powder, the calcination atmosphere and humidity, and the selection of the support during the preparation process. Applying this molybdenum-based bimetallic catalyst to the production of bio-jet fuel via fatty acid / ester hydrodeoxygenation significantly reduces the reaction temperature of the hydrodeoxygenation stage compared to existing technologies, thereby reducing carbon loss and increasing the yield of bio-jet fuel. Furthermore, the catalyst preparation process provided by this invention is simple, easy to operate, and operates under mild conditions, making it more suitable for industrial application and promotion.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a Mo-based bimetallic catalyst, characterized in that, include: S1. A hydrophilic metal is loaded onto a support by an impregnation method and dried to obtain a catalyst precursor. The hydrophilic metal is Ir, Pt, Pd, Ru or Rh. S2. Mix the catalyst precursor from step S1 with the solid molybdenum salt and grind it thoroughly to obtain a mixed powder. S3. The mixed powder from step S2 is calcined in air or an inert gas atmosphere to obtain a Mo-based bimetallic catalyst. The humidity in the air range is 5-35%RH, and the calcination temperature is 300-800℃. In the Mo-based bimetallic catalyst, the mass percentage of the hydrophilic metal is 1.0% to 5.0%, and the mass percentage of molybdenum is 0.4% to 8.0%.

2. The method for preparing the Mo-based bimetallic catalyst according to claim 1, characterized in that, The carrier includes one or more of activated carbon, alumina, molecular sieve SBA-15, MCM-41, and silica.

3. The method for preparing the Mo-based bimetallic catalyst according to claim 1, characterized in that, The specific steps of step S1 include: The catalyst precursor was prepared by adding the hydrophilic metal precursor solution dropwise to the support and impregnating it for 1-12 hours, followed by drying at 50-120°C for 6-16 hours.

4. The method for preparing the Mo-based bimetallic catalyst according to claim 3, characterized in that, The hydrophilic metal precursor is selected from one or more of chloroiridic acid, iridium chloride, potassium chloroiridate, chloroplatinic acid, platinum nitrate, tetraammineplatinum nitrate, potassium chloroplatinate, palladium chloride, palladium nitrate, ruthenium chloride, ruthenium acetylacetonate, rhodium chloride, and rhodium acetylacetonate.

5. The method for preparing the Mo-based bimetallic catalyst according to claim 1, characterized in that, The solid molybdenum salt is selected from one or more of ammonium molybdate, sodium molybdate, molybdenum carbide, or molybdenum oxide.

6. The method for preparing the Mo-based bimetallic catalyst according to claim 1, characterized in that, The particle size of the mixed powder is 50~500 mesh.

7. A Mo-based bimetallic catalyst prepared by the method according to any one of claims 1-6.

8. The application of the Mo-based bimetallic catalyst according to claim 7 in the catalytic hydrodeoxygenation of fatty acids / esters to prepare bio-jet fuel.

9. The application of the Mo-based bimetallic catalyst according to claim 8 in the catalytic hydrodeoxygenation of fatty acids / esters to prepare bio-jet fuel, wherein in the hydrogenation stage, the mass ratio of the Mo-based bimetallic catalyst to stearic acid / methyl stearate is 1%~10%, the reaction temperature is 100~200°C, and the hydrogen pressure range is 0.5~6 MPa; in the isomerization stage, the hydrogen partial pressure is 4~10 MPa, the reaction temperature is 200~350°C, and the liquid hourly space velocity is 0.2~3 h⁻¹. -1 The volume ratio of hydrogen to the material entering the reactor is 500–1200.

10. The application of the Mo-based bimetallic catalyst according to claims 8 and 9 in the catalytic hydrodeoxygenation of fatty acids / esters to prepare bio-jet fuel, wherein the fatty acids / esters used are products obtained from the transesterification / hydrolysis of vegetable oils and have a carbon number range of C8 to C18.

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