A methyl esterification catalyst, a preparation method thereof and a method for producing aviation fuel from waste oil

Abstract

The application discloses a kind of methyl esterification catalyst and preparation method and the method for producing aviation fuel of waste oil, belong to the technical field of catalyst for biological oil, and its technical scheme main point is a kind of methyl esterification catalyst, including bentonite carrier and zirconium nickel phosphide, the loading capacity of zirconium nickel phosphide on bentonite carrier is 15-25%, the methyl esterification reaction process of the bentonite loaded zirconium nickel phosphide catalyst provided in the present application in waste oil is not only high in catalytic activity, easy to separate, and its specific metal combination and acid site provide ideal raw material for subsequent hydrogenation step, and the yield of aviation fuel component and low-temperature performance are greatly improved in cooperation with hydrogenation catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalysts for bio-oils, and in particular to a methyl esterification catalyst and its preparation method, as well as a method for producing aviation fuel from waste oils. Background Technology

[0002] With the development of the global economy, the aviation industry has made significant progress, bringing great convenience to people's travel and cargo transportation. However, the current high dependence of the global aviation industry on traditional fossil fuels has generated a large amount of carbon emissions. Therefore, against this backdrop, the development of sustainable alternative aviation fuels has become a research hotspot in the global aviation industry and scientific research fields. Waste oil, as a potential biomass resource, has received widespread attention in the development of alternative aviation fuels due to its renewable and widely available sources.

[0003] In existing technologies, various methods are typically employed to convert waste oils into aviation fuel. During the methylation process of waste oils, homogeneous alkaline catalysts are generally used. In the subsequent hydrogenation process, conventional hydrorefining catalysts, such as Ni-Mo / Al2O3 and Co-Mo / Al2O3, are commonly used. These methods have achieved the conversion of waste oils into aviation fuel to a certain extent and are widely used in the field of aviation fuel substitution research.

[0004] The existing technology uses homogeneous alkaline catalysts for the methyl esterification of waste oils, which has problems such as difficulty in catalyst recovery and wastewater generation. In the subsequent hydrogenation process, conventional hydrorefining catalysts generally have problems such as low hydrodeoxygenation efficiency and poor cracking selectivity when converting oil methyl esters into chain hydrocarbons. This results in low yield of aviation fuel components and an unsatisfactory proportion of isoalkanes in the products, which in turn affects the low-temperature fluidity and combustion performance of the fuel. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a methyl esterification catalyst and its preparation method, as well as a method for producing aviation fuel from waste oils. The bentonite-supported zirconium-nickel phosphide catalyst provided in this application not only exhibits high catalytic activity and ease of separation during the methyl esterification reaction of waste oils, but also provides ideal raw materials for subsequent hydrogenation steps due to its specific metal combination and acidic sites. The synergistic effect with the hydrogenation catalyst significantly improves the yield and low-temperature performance of aviation fuel components.

[0006] The first aspect of the present invention is to provide a methyl esterification catalyst, which adopts the following technical solution:

[0007] A methyl esterification catalyst comprising a bentonite support and a zirconium nickel phosphate, wherein the zirconium nickel phosphate is loaded at a rate of 15-25% on the bentonite support.

[0008] By employing the above technical solution, a methyl esterification catalyst formed by zirconium-nickel phosphide supported on a bentonite carrier is developed, in which metals such as zirconium and nickel play important roles in the methyl esterification process of waste oil. Zirconium helps to increase the number and activity of the catalyst's active sites, accelerating the transesterification reaction between waste oil and methanol and increasing the reaction rate; nickel enhances the catalyst's adsorption capacity for reactant molecules, making it easier for waste oil and methanol to react on the catalyst surface, thereby improving the efficiency of the methyl esterification reaction. 0 or Niδ + The sites are crucial for the dissociation and activation of hydrogen, which is extremely critical for the hydrodeoxygenation step in subsequent aviation fuel production. Phosphorus, as a structural stabilizer and electron modulator, forms a stable phosphide crystal structure with zirconium and nickel, preventing the metal components from being over-reduced or sintered during the reaction. Moreover, the introduction of phosphorus can regulate the electron density of the metal sites, putting them in an electron-deficient state, which is generally beneficial for the adsorption and activation of oxygen-containing compounds (such as carboxyl groups in oils). Furthermore, the catalyst has a zirconium-nickel phosphide loading of 15-25%, ensuring that the catalyst has good catalytic performance and stability. Compared with liquid homogeneous alkaline catalysts, the solid catalyst of this application can be better separated and recovered from the reaction liquid substances, and also avoids the wastewater problem generated when using water washing to separate the homogeneous alkaline catalyst from the reactants in the prior art.

[0009] A preferred embodiment of the methyl esterification catalyst is as follows: in the zirconium nickel phosphide, the molar ratio of zirconium, nickel and phosphorus is 1:(0.8-1.2):(1.5-2.5).

[0010] By employing the above technical solution, the molar ratio of zirconium, nickel, and phosphorus in the zirconium-nickel phosphide is controlled within the range of 1:(0.8-1.2):(1.5-2.5). This ensures that the catalyst has sufficient nickel to provide adequate hydrogenation active sites, while avoiding excessive coverage or disruption of the stable structure formed by zirconium and phosphorus. Furthermore, the close molar number of zirconium and nickel facilitates the formation of a Zr-Ni-P composite phase. This composite phase, with its closely adjacent Lewis acid sites of zirconium and hydrogenation sites of nickel, significantly improves reaction efficiency. Sufficient phosphorus ensures complete phosphating of zirconium-nickel metal, forming thermodynamically stable phosphide crystals, endowing the catalyst with excellent acid resistance and anti-sintering ability. Moreover, an appropriate amount of phosphorus moderately reduces the electron density of nickel sites, which is beneficial for adsorbing and activating O atoms in reactant molecules, thereby improving the activity of transesterification and hydrodeoxygenation. Therefore, controlling the molar ratio of zirconium, nickel, and phosphorus within the above range can enable the methyl esterification catalyst to have good activity and selectivity, improve the methyl esterification reaction efficiency of waste oils, reduce the occurrence of side reactions, and help improve the hydrodeoxygenation efficiency and cracking selectivity in the subsequent hydrogenation process, thereby increasing the yield of aviation fuel components, increasing the proportion of isoalkanes in the products, and improving the low-temperature fluidity and combustion performance of the fuel.

[0011] When the nickel content is too low, the catalyst lacks sufficient active sites to activate hydrogen, resulting in a slow rate of subsequent hydrodeoxygenation reaction and low conversion efficiency. If the nickel content is too high, the excess nickel may not be fully integrated into the framework of zirconium phosphate crystals, leading to its own agglomeration and formation of larger particles, which can easily lead to deactivation due to carbon deposition or sintering.

[0012] If the phosphorus content is too low, not all the metal can be converted into phosphides, resulting in some metal existing in the form of oxides. Metal oxides are unstable under reaction conditions and are prone to hydrolysis, loss, and structural collapse. Furthermore, when phosphorus is insufficient, a stable Ni2P structure cannot be formed. Nickel is prone to migration, agglomeration, and sintering into large particles during the reaction and regeneration process, leading to a rapid decrease in activity. Although unphosphated zirconium oxide can catalyze the reaction due to its strong Lewis acid properties, it is also prone to side reactions such as carbon deposition and coking, which can clog the catalyst pores and cause it to deactivate rapidly.

[0013] Excessive phosphorus may deposit on the catalyst surface in the form of phosphates, covering the active sites of nickel and zirconium, preventing reactants from contacting the active centers and causing a significant decrease in catalyst activity.

[0014] The second aspect of the present invention is to provide a method for preparing the above-mentioned methyl esterification catalyst, comprising the following steps: impregnating a bentonite support in an aqueous solution containing a zirconium source, a nickel source and a phosphorus source, drying it and then calcining it at 400-500°C for 3-5 hours, then reducing it at 350-400°C for 2-4 hours in a hydrogen atmosphere, and cooling it to obtain the methyl esterification catalyst.

[0015] A preferred embodiment of the preparation method of the methyl esterification catalyst is as follows: an inert gas is introduced for protection during cooling.

[0016] By adopting the above technical solution, inert gas is introduced during the cooling stage of the methyl esterification catalyst preparation process to prevent the catalyst from being oxidized, ensuring the performance and quality of the methyl esterification catalyst. This is beneficial for the subsequent efficient use of the catalyst in the methyl esterification reaction of waste oils, thereby providing a guarantee for the efficient and selective conversion of waste oils into high-quality aviation fuel.

[0017] A third aspect of the present invention is to provide a method for producing aviation fuel from waste oil, comprising the following steps:

[0018] S1. Methyl esterification: Using the catalyst obtained above, waste oil is subjected to transesterification reaction with methanol to obtain fatty acid methyl esters.

[0019] S2, Hydrogenation treatment: Fatty acid methyl esters are subjected to preliminary hydrogenation treatment under hydrogen conditions;

[0020] S3, Hydrogenation Conversion: The material after preliminary treatment in step S2 is subjected to deep hydrodeoxygenation and cracking reaction with a hydrogenation catalyst under hydrogen conditions;

[0021] S4. Separation and fractionation yield aviation fuel.

[0022] In a preferred embodiment of the method for producing aviation fuel from waste oil, the amount of catalyst used in step S1 is 2.0-3.0% of the total weight of waste oil and methanol.

[0023] A preferred embodiment of the method for producing aviation fuel from waste oil is that the transesterification reaction conditions in step S1 are: temperature 60-80℃, pressure 0.1-0.3MPa, and reaction time 3-4h.

[0024] A preferred embodiment of the method for producing aviation fuel from waste oil is that the hydrogenation treatment conditions in step S2 are: temperature 200-250℃, pressure 3.0-5.0MPa, and reaction time 1.5-2h.

[0025] A preferred embodiment of the method for producing aviation fuel from waste oil is as follows: the hydrogenation conversion conditions in step S3 are: temperature 300-350℃, reaction time 2.5-3h, and hydrogen to raw material volume ratio of (100-200):1.

[0026] In a preferred embodiment of the method for producing aviation fuel from waste oil, the hydrogenation catalyst in step S3 is a modified zeolite molecular sieve supported molybdenum-cobalt catalyst.

[0027] In summary, the present invention has the following beneficial effects:

[0028] 1. The methyl esterification catalyst supported on bentonite carrier, which has high catalytic activity and is easy to separate during the methyl esterification reaction of waste oil, solves the problems of difficult recovery and wastewater generation of homogeneous alkaline catalysts.

[0029] 2. This methyl esterification catalyst provides an ideal feedstock for the subsequent hydrogenation step. It exhibits a significant synergistic effect with the hydrogenation catalyst modified zeolite molecular sieve supported molybdenum-cobalt catalyst. This synergistic effect enables waste oils to achieve deep hydrodehydrogenation and highly selective cracking isomerization under relatively mild hydrogenation conditions during the conversion process. This significantly improves the yield and low-temperature performance of aviation fuel components, with a total yield of over 84%. Moreover, the obtained aviation fuel components have a sulfur content of less than 10 ppm, a freezing point of less than -40°C, a smoke point of greater than 25 mm, and a cetane number of greater than 60. Key indicators such as freezing point and viscosity are all better than the standard requirements.

[0030] 3. The bentonite-supported zirconium-nickel phosphide catalyst obtained in this application can treat waste oil raw materials from various sources, including waste cooking oil, etc., and has good industrial application prospects. It also has significant environmental efficiency, realizing the high-value utilization of waste resources and reducing the consumption of fossil fuels and environmental pollution. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the embodiments. All reagents, unless otherwise specified, are commercially available conventional reagent products.

[0032] Example 1

[0033] A method for preparing a methyl esterification catalyst includes the following steps:

[0034] The feed was prepared with a zirconium nickel phosphate loading of 20% on the bentonite carrier.

[0035] S1, zirconium nitrate, nickel nitrate hexahydrate and ammonium dihydrogen phosphate are mixed and dissolved in water at a zirconium, nickel and phosphorus molar ratio of 1:1:2 to form a mixed solution with a solid-liquid ratio of 1:3.

[0036] S2. Weigh out bentonite carrier (specific surface area of ​​220 m²). 2 The bentonite support was immersed in the above mixed solution, allowed to stand at room temperature for 12 h, then dried at 120 °C for 4 h, calcined at 450 °C for 4 h, and then reduced at 380 °C for 3 h in a hydrogen atmosphere. After the reduction reaction was completed, the bentonite-supported zirconium nickel phosphate was obtained by cooling under an inert atmosphere.

[0037] Example 2

[0038] A method for preparing a methyl esterification catalyst includes the following steps:

[0039] The feed was prepared with a zirconium nickel phosphate loading of 15% on the bentonite carrier.

[0040] S1, zirconium nitrate, nickel nitrate hexahydrate and ammonium dihydrogen phosphate are mixed with water at a zirconium, nickel and phosphorus molar ratio of 1:0.8:1.5 to form a mixed solution with a solid-liquid ratio of 1:3.

[0041] S2. Weigh out bentonite carrier (specific surface area of ​​220 m²). 2 The bentonite support was immersed in the above mixed solution, allowed to stand at room temperature for 12 h, then dried at 120 °C for 4 h, calcined at 400 °C for 5 h, and then reduced at 350 °C for 4 h in a hydrogen atmosphere. After the reduction reaction was completed, the bentonite-supported zirconium nickel phosphide was obtained by cooling under an inert atmosphere.

[0042] Example 3

[0043] A method for preparing a methyl esterification catalyst includes the following steps:

[0044] The feed was prepared with a zirconium nickel phosphate loading of 25% on the bentonite carrier.

[0045] S1, zirconium nitrate, nickel nitrate hexahydrate and ammonium dihydrogen phosphate are mixed and dissolved in water at a zirconium, nickel and phosphorus molar ratio of 1:1.2:2.5 to form a mixed solution with a solid-liquid ratio of 1:3.

[0046] S2. Weigh out bentonite carrier (specific surface area of ​​220 m²). 2 The bentonite support was immersed in the above mixed solution, allowed to stand at room temperature for 12 hours, then dried at 120°C for 4 hours, calcined at 500°C for 3 hours, and then reduced at 400°C for 2 hours in a hydrogen atmosphere. After the reduction reaction was completed, the bentonite-supported zirconium nickel phosphate was obtained by cooling under an inert atmosphere.

[0047] Comparative Example 1

[0048] A method for preparing a methyl esterification catalyst differs from Example 1 in that a molybdenum source (NH4)2MoO4 is used instead of a zirconium source, zirconium nitrate, and a bentonite-supported nickel-molybdenum-phosphorus catalyst is prepared according to a nickel, molybdenum, and phosphorus molar ratio of 1:1:2. All other preparation steps are the same as in Example 1.

[0049] Comparative Example 2

[0050] A method for preparing a methyl esterification catalyst differs from Example 1 in that a commercially available alumina support is used instead of a bentonite support to obtain alumina-supported zirconium nickel phosphide. All other preparation steps are the same as in Example 1.

[0051] Comparative Example 3

[0052] A method for preparing a methyl esterification catalyst differs from Example 1 in that the molar ratio of zirconium, nickel, and phosphorus is 1:1.5:1.2, while the other preparation steps are the same as in Example 1.

[0053] Comparative Example 4

[0054] A method for preparing a methyl esterification catalyst differs from Example 1 in that the molar ratio of zirconium, nickel, and phosphorus is 1:0.5:2.8, while the other preparation steps are the same as in Example 1.

[0055] The catalysts prepared using the above examples and comparative examples were applied to the production of aviation fuel from waste oil, wherein the waste oil was catering waste oil with an acid value of 25 mg KOH / g, a moisture content of 0.8%, and an oxygen content of 12.0 wt%. The specific production method is as follows:

[0056] Application Example 1

[0057] A method for producing aviation fuel from waste oil includes the following steps:

[0058] S1. Methyl esterification: The bentonite-supported zirconium nickel phosphide catalyst obtained in Example 1 above, waste oil and methanol are added to the reactor, and transesterification reaction is carried out at a temperature of 60°C, a pressure of 0.1 MPa and a reaction time of 4 h to obtain fatty acid methyl ester. The amount of catalyst added is 2.0% of the total weight of waste oil and methanol, and the molar ratio of waste oil to methanol is 1:9.

[0059] S2. Hydrogenation treatment: Fatty acid methyl esters are subjected to preliminary hydrogenation treatment under hydrogen conditions at a temperature of 200℃ and a pressure of 3.0MPa for 2 hours.

[0060] S3. Hydrogenation Conversion: The material after preliminary treatment in step S2 is subjected to deep hydrodeoxygenation and cracking with a hydrogenation catalyst under hydrogen conditions. The reaction temperature is 300℃, the reaction time is 3h, the volume ratio of hydrogen to feedstock is 100:1, and the space velocity is 2h. ﹣1 The amount of hydrogenation catalyst used is 0.01% of the original waste oil weight. The hydrogenation catalyst is a modified zeolite molecular sieve supported molybdenum-cobalt catalyst. Its preparation method is the same as the preparation method in our patent CN120790211A. The molecular sieve support accounts for 97.5%, and the total proportion of molybdenum source and cobalt source is 2.5%. There are no auxiliary metals in the raw materials. The weight ratio of molybdenum to cobalt is 3:1.

[0061] S4. Separation and fractionation yield aviation fuel.

[0062] Application Example 2

[0063] A method for producing aviation fuel from waste oil includes the following steps:

[0064] S1. Methyl esterification: The bentonite-supported zirconium nickel phosphide catalyst obtained in Example 2 above, waste oil and methanol are added to the reactor, and transesterification reaction is carried out at a temperature of 70°C, a pressure of 0.2 MPa and a reaction time of 4 h to obtain fatty acid methyl ester. The amount of catalyst added is 2.5% of the total weight of waste oil and methanol, and the molar ratio of waste oil to methanol is 1:9.

[0065] S2. Hydrogenation treatment: Fatty acid methyl esters were subjected to preliminary hydrogenation treatment under hydrogen conditions at a temperature of 230℃ and a pressure of 4.0MPa for 2 hours.

[0066] S3. Hydrogenation Conversion: The material after preliminary treatment in step S2 is subjected to deep hydrodeoxygenation and cracking with a hydrogenation catalyst under hydrogen conditions. The reaction temperature is 330℃, the reaction time is 3h, the volume ratio of hydrogen to feedstock is 150:1, and the space velocity is 2h. ﹣1The amount of hydrogenation catalyst used is 0.01% of the original waste oil weight. The hydrogenation catalyst is a modified zeolite molecular sieve supported molybdenum-cobalt catalyst. Its preparation method is the same as the preparation method in our patent CN120790211A. The molecular sieve support accounts for 97.5%, and the total proportion of molybdenum source and cobalt source is 2.5%. There are no auxiliary metals in the raw materials. The weight ratio of molybdenum to cobalt is 3:1.

[0067] S4. Separation and fractionation yield aviation fuel.

[0068] Application Example 3

[0069] A method for producing aviation fuel from waste oil includes the following steps:

[0070] S1. Methyl esterification: The bentonite-supported zirconium nickel phosphide catalyst obtained in Example 3 above, waste oil and methanol are added to the reactor, and transesterification reaction is carried out at a temperature of 80°C, a pressure of 0.3 MPa and a reaction time of 3 h to obtain fatty acid methyl ester. The amount of catalyst added is 3.0% of the total weight of waste oil and methanol, and the molar ratio of waste oil to methanol is 1:9.

[0071] S2. Hydrogenation treatment: Fatty acid methyl esters are subjected to preliminary hydrogenation treatment under hydrogen conditions at a temperature of 250℃ and a pressure of 5.0MPa for 1.5h.

[0072] S3. Hydrogenation Conversion: The material initially treated in step S2 is subjected to deep hydrodeoxygenation and cracking with a hydrogenation catalyst under hydrogen conditions. The reaction temperature is 350℃, the reaction time is 2.5h, the hydrogen to feedstock volume ratio is 200:1, and the space velocity is 2h⁻¹. ﹣1 The amount of hydrogenation catalyst used is 0.01% of the original waste oil weight. The hydrogenation catalyst is a modified zeolite molecular sieve supported molybdenum-cobalt catalyst. Its preparation method is the same as the preparation method in our patent CN120790211A. The molecular sieve support accounts for 97.5%, and the total proportion of molybdenum source and cobalt source is 2.5%. There are no auxiliary metals in the raw materials. The weight ratio of molybdenum to cobalt is 3:1.

[0073] S4. Separation and fractionation yield aviation fuel.

[0074] Application Example 4

[0075] A method for producing aviation fuel from waste oils differs from Application Example 1 in that the catalyst in step S1 uses the bentonite-supported nickel-molybdenum-phosphorus catalyst obtained in Comparative Example 1, while all other aspects are the same as in Application Example 1.

[0076] Application Example 5

[0077] A method for producing aviation fuel from waste oils differs from Application Example 1 in that the catalyst in step S1 uses the alumina-supported zirconium-nickel phosphide catalyst obtained in Comparative Example 2, while all other aspects are the same as in Application Example 1.

[0078] Application Example 6

[0079] A method for producing aviation fuel from waste oils differs from Application Example 1 in that the catalyst in step S1 uses the bentonite-supported zirconium-nickel phosphate catalyst obtained in Comparative Example 3, while all other aspects are the same as in Application Example 1.

[0080] Application Example 7

[0081] A method for producing aviation fuel from waste oils differs from Application Example 1 in that the catalyst in step S1 uses the bentonite-supported zirconium-nickel phosphide catalyst obtained in Comparative Example 4, while all other aspects are the same as in Application Example 1.

[0082] Comparison Example

[0083] A method for producing aviation fuel from waste oils differs from Application Example 1 in that the methyl esterification catalyst bentonite-supported zirconium nickel phosphate is not added in step S1, while all other steps are the same as in Application Example 1.

[0084] Performance testing

[0085] The sulfur content, freezing point, smoke point, cetane number, and viscosity of the aviation fuels obtained in the above application examples and control examples were tested. The test results are shown in Table 1. The sulfur content was tested according to the ASTM D5453 ultraviolet fluorescence method, the freezing point was tested according to the ASTM D5972 automatic phase change method, the smoke point was tested according to the ASTM D1322 smoke lamp method, the cetane number was tested according to the ASTM D613 engine method, and the viscosity was tested according to the ASTM D445 capillary method.

[0086] Table 1. Results of Aviation Fuel Yield and Performance Testing

[0087] project Yield % Sulfur content (ppm) Freezing point ℃ Smoke point mm cetane number ° <![CDATA[Viscosity at -40°C, mm 2 / s]]> ASTM D7566 requirements / ≤15 ≤﹣40 ≥25 ≥60 ≤8 Application Example 1 84.2 6.3 ﹣43.5 26.8 64.5 5.2 Application Example 2 86.7 5.2 ﹣45.2 27.5 65.8 4.8 Application Example 3 85.9 5.1 ﹣45.3 27.1 65.7 4.9 Application Example 4 72.3 18.6 ﹣38.2 23.2 58.2 7.8 Application Example 5 65.7 42.6 ﹣33.4 20.5 52.3 10.5 Application Example 6 58.6 45.8 ﹣26.8 16.3 41.6 12.6 Application Example 7 61.3 44.5 ﹣27.4 17.5 43.8 12.8 Comparison Example 49.5 52.8 ﹣18.3 15.7 37.6 12.9

[0088] Based on the test data in Table 1:

[0089] When the bentonite-supported zirconium-nickel phosphate catalysts obtained in Examples 1-3 of this application are used for the methylation treatment of waste oils, the yield of aviation fuel obtained in Examples 1-3 is significantly higher than that in the control examples. This shows that the bentonite-supported zirconium-nickel phosphate catalyst of this application enables high methylation efficiency of waste oils, providing a raw material with more uniform composition, fewer impurities, and better reactivity for subsequent hydrogenation treatment. This makes the subsequent hydrogenation process more stable and efficient. At the same time, the bentonite-supported zirconium-nickel phosphate catalyst provides active sites for the subsequent hydrogenation reaction, improving the efficiency of oil hydrogenation and deoxygenation. When combined with the hydrogenation catalyst, it effectively improves the yield of aviation fuel from waste oils, while also effectively ensuring the quality of aviation fuel.

[0090] Compared with Application Example 1, Application Examples 4-5 used bentonite-supported nickel-molybdenum phosphate catalysts and alumina-supported zirconium-nickel phosphate catalysts obtained in Comparative Examples 1-2, respectively. However, the aviation fuel yield obtained in Application Examples 4-5 was low, and the performance of the aviation fuel was significantly lower than that obtained in Application Example 1. The reasons may be that the bentonite-supported nickel-molybdenum phosphate catalyst caused excessive cracking of waste oil, generating too much light naphtha (C5-C7), which reduced the aviation fuel yield and quality. In the alumina-supported zirconium-nickel phosphate catalyst, the alumina support reacted with phosphorus, resulting in an incomplete phosphate phase. At the same time, the strong acid sites on the support caused coking to cover the active sites, reducing the activity and stability of the catalyst. Therefore, the combination between the active component and the support in the catalyst of this application effectively ensures the catalytic activity of the catalyst.

[0091] Compared with Application Example 1, Application Examples 6-7 used the catalyst obtained from Comparative Example 3-4. In the catalyst of Comparative Example 3-4, the molar ratio of nickel to phosphorus was not within the range specified in this application. As can be seen from the yield and mass of aviation fuel in Application Examples 6-7, when the molar ratio of nickel to phosphorus was not within the range specified in this application, it significantly affected the catalytic activity of the catalyst, resulting in a significant reduction in both the yield and mass of aviation fuel.

[0092] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A catalyst for the methylesterification of waste oils, characterized by: The catalyst comprises a bentonite carrier and a zirconium-nickel phosphide, the loading amount of the zirconium-nickel phosphide on the bentonite carrier is 15-25%, and the molar ratio of zirconium, nickel and phosphorus in the zirconium-nickel phosphide is 1:(0.8-1.2):(1.5-2.5). The preparation method of the catalyst comprises the following steps: dipping the bentonite carrier in an aqueous solution containing a zirconium source, a nickel source and a phosphorus source, drying, calcining at 400-500 DEG C for 3-5 h, then reducing in a hydrogen atmosphere at 350-400 DEG C for 2-4 h, and cooling to obtain the catalyst; and inert gas is introduced for protection during the cooling.

2. A method for preparing a catalyst for methyl esterification of waste oil according to claim 1, characterized by, The preparation method of the catalyst comprises the following steps: dipping the bentonite carrier in an aqueous solution containing a zirconium source, a nickel source and a phosphorus source, drying, calcining at 400-500 DEG C for 3-5 h, then reducing in a hydrogen atmosphere at 350-400 DEG C for 2-4 h, and cooling to obtain the catalyst; and inert gas is introduced for protection during the cooling.

3. A method for producing aviation fuel from waste oil, characterized by, The preparation method of the catalyst comprises the following steps: S1, methyl esterification: using the catalyst of claim 1 to perform ester exchange reaction of waste oil and fat with methanol to obtain fatty acid methyl ester; S2, hydrotreating: performing preliminary hydrotreating of the fatty acid methyl ester under hydrogen condition; S3, hydroconversion: performing deep hydrodeoxygenation and cracking reaction of the material after the preliminary treatment of step S2 under hydrogen condition with a hydrogenation catalyst; S4, separating and fractionating to obtain aviation fuel.

4. The method of producing aviation fuel from waste oil according to claim 3, wherein: The amount of the catalyst used in step S1 is 2.0-3.0% of the total weight of the waste oil and fat and methanol.

5. The method of producing aviation fuel from waste oil according to claim 3, wherein: The ester exchange reaction conditions in step S1 are: temperature 60-80 DEG C, pressure 0.1-0.3 MPa, and reaction time 3-4 h.

6. The method of producing aviation fuel from waste oil according to claim 3, wherein: The hydrotreating conditions in step S2 are: temperature 200-250 DEG C, pressure 3.0-5.0 MPa, and reaction time 1.5-2 h.

7. The method of producing aviation fuel from waste oil according to claim 3, wherein: The hydroconversion conditions in step S3 are: temperature 300-350 DEG C, reaction time 2.5-3 h, and the volume ratio of hydrogen to raw material is (100-200):

1.

8. The method of producing aviation fuel from waste oil according to claim 3, wherein: The hydrogenation catalyst in step S3 is a modified zeolite molecular sieve supported molybdenum-cobalt catalyst.