A process for the preparation of an olefin oligomerisation catalyst

Abstract

The present application relates to the field of environmental protection catalytic material technology, and discloses a preparation method of an olefin oligomerization catalyst, wherein a zeolite molecular sieve is added into an acid solution, stirred at 60-100 DEG C, filtered, washed to neutral, dried, then added into a salt solution containing polyvalent metal cations, stirred at 25-100 DEG C, filtered, washed to neutral, dried, and calcined at 400-600 DEG C to obtain the olefin oligomerization catalyst.The catalyst prepared by the method retains the acid center of the microporous structure and the shape-selective characteristics, and the diffusion and transport performance of the guest molecules in the pore channel is improved due to the existence of the mesopore, and the polyvalent cations can precisely regulate the acid center of the molecular sieve, so that the catalyst has the characteristics of high activity, high selectivity and good stability.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly catalytic materials technology, and in particular to a method for preparing an olefin oligomerization catalyst. Background Technology

[0002] Aviation kerosene's main components are chain alkanes, cycloalkanes, and aromatics with a carbon number ranging from C8 to C16. The content of each component is similar across different types of aviation kerosene, with an average composition of: chain alkanes (60 vol%), cycloalkanes (20 vol%), and aromatics (20 vol%). Ethanol jet fuel (ATJ) is a sustainable aviation fuel (SAF) certified by the American Society for Testing and Materials (ASTM), allowing a blending ratio of up to 50%. The ATJ process involves fermenting sugar and starch-based raw materials to produce alcohols, which are then converted into SAF through dehydration, oligomerization, hydroconversion, and distillation. Oligomerization involves polymerizing the C3-C4 low-carbon olefins obtained from alcohol dehydration into C8-C16 aviation kerosene segments.

[0003] Olefin oligomerization is a typical acid-catalyzed reaction. Traditional olefin oligomerization catalysts are mostly liquids, such as sulfuric acid and toluenesulfonic acid. These catalysts have poor selectivity, low product purity, are difficult to separate, are corrosive to equipment, and are difficult to scale up for continuous production. In recent years, environmentally friendly catalysts have gradually become a research hotspot for olefin oligomerization reaction catalysts, mainly including solid phosphoric acid catalysts, molecular sieve catalysts, oxide catalysts, acidic resin catalysts, and acidic ionic liquid catalysts.

[0004] European patent EP0371938 discloses a method for preparing a phosphoric acid / SiO2 catalyst. This catalyst is used in the oligomerization reaction of isobutylene to produce gasoline, and the gasoline yield is significantly improved compared with that of conventional phosphoric acid / diatomite catalysts. At the start of the reaction, the gasoline yield is 100%, while the gasoline yield with conventional catalysts is only 40%. Although the gasoline yield decreases as the reaction proceeds, it is still at least 40% higher than that using conventional catalysts. Furthermore, this catalyst has advantages such as high strength, long lifespan, and easy disassembly. CN1810742A discloses a method for the selective dimerization of isobutylene to produce isooctene, using phosphoric acid-supported silica as a catalyst, at a reaction temperature of 40–200 °C, a reaction pressure of atmospheric pressure to 6 MPa, and a volume hourly space velocity of 0.5–3 h⁻¹. -1 Under these conditions, the isobutylene conversion rate is 100%, and the isooctene selectivity is greater than 80%.

[0005] CN113145162A reports a Si / M / ZSM-5 molecular sieve, its preparation method, and its applications. Metal M is selected from at least one of alkaline earth metals, Zn, Fe, Co, Ni, and rare earth metals. Its use in catalyzing isobutylene dimerization can further improve the selectivity of isobutylene dimerization while maintaining a high isobutylene conversion rate. CN107286983A reports a method for preparing gasoline components through the oligomerization of C4 olefins. Using ZSM-35 with a SiO2 / Al2O3 molar ratio of 20-40 as a catalyst, and with a reaction temperature of 310-350 °C and a reaction pressure of 0.2-1 MPa, this technical solution effectively solves the problems of low liquid yield and high aromatic content in C4 olefin oligomerized gasoline components. CN110721734A reports a catalyst, preparation method, and application for the preparation of aviation fuel and gasoline by olefin oligomerization. The catalyst is a mixture of 70%–95% (by mass) nano-ZSM-5 molecular sieve and 5%–30% pseudoboehmite. The reaction is carried out at a temperature of 220–320 °C, a pressure of 1–6 MPa, and a mass hourly space velocity of 0.5–6 h⁻¹. -1 Under the specified process conditions, the conversion rate of low-carbon olefins can reach over 99%, the oil yield over 95%, and the selectivity of aviation fuel over 90%, with gasoline co-produced during the aviation fuel generation process. CN111229304A reports a Fenton reagent-modified ZSM-5 molecular sieve catalyst, its preparation method, and its application, under reaction conditions of 220–320 °C, 1–6 MPa, and 0.5–6 h⁻¹. -1 Under the specified conditions, the reaction exhibits excellent catalytic activity for low-carbon olefins and their mixtures between C2 and C7, with an olefin conversion rate exceeding 98% and a jet fuel selectivity exceeding 90%. Furthermore, gasoline is co-produced during the jet fuel generation process. CN115487860A reports a composite supported Co... A method for preparing and applying Zn / β molecular sieve catalysts for the selective oligomerization of isobutylene was disclosed in CN103316708A. The catalysts utilize La- or Zr-supported mesoporous H-type MSU-SMFI as catalysts, and the reaction conditions are described as follows: reaction temperature 190–320 °C, reaction pressure 3–5 MPa, and volume hourly space velocity 0.5–5 h⁻¹. -1 Under the specified process conditions, the conversion rate of C3-C4 low-carbon olefins is greater than 90%, and the selectivity of diesel fuel is greater than 70%. CN103894225A reports an aluminum trichloride supported catalyst, its preparation method, and its application. Gaseous AlCl3 is adsorbed onto β or ZSM-5 molecular sieves, and the reaction is carried out at a temperature of 0-50 °C, a pressure of 1-3 MPa, and a liquid hourly space velocity of 0.5-2 h⁻¹. -1Under the process conditions, the yield of liquid products and C8 olefins in the butene oligomerization reaction are both greater than 80%.

[0006] US Patent 5510555 reports a silica-alumina oxide that can be used for isobutylene oligomerization. After reacting at 60–65 °C for 1 h, the isobutylene conversion is 99%, with selectivities of 50%, 43%, and 5% for dimers, trimers, and tetramers, respectively. CN108246342A reports an in-situ synthesis method for a nickel-based propylene oligomerization molecular sieve catalyst, using a zeolite molecular sieve with a NiO-supported SiO2 / Al2O3 mass ratio of 15–50 as the catalyst, at a reaction temperature of 160 °C, a reaction pressure of 2.5 MPa, and a mass hourly space velocity of 2.0 h⁻¹. -1 Under the specified process conditions, the propylene conversion rate is greater than 99%, the nonene selectivity is greater than 60%, and the dodecene selectivity is greater than 28%. CN113354507A reports a method for the oligomerization of isobutylene using a SiO2-Al2O3 composite oxide with a SiO2 / Al2O3 mass ratio of 2–5 as a catalyst, at a reaction temperature of 80–140 °C, a reaction pressure of 3–5.5 MPa, and a space velocity of 1–3.0 h⁻¹. -1 Under the given process conditions, both isobutylene conversion and isooctene selectivity are greater than 90%.

[0007] CN103447089A reports a low-carbon olefin copolymerization catalyst and its preparation method, using a styrene-based cation exchange resin containing pyrrolidone in its framework as the catalyst. This catalyst is suitable for processes such as propylene oligomerization to produce nonene and dodecene, C4 olefin copolymerization to produce high-octane gasoline, and isobutylene dimerization to produce isooctene. CN107457001A reports a polystyrene sulfonic acid resin catalyst, its preparation method, and its applications, achieving a single-pass conversion rate greater than 90% and a diisobutylene selectivity greater than 80% in catalyzing isobutylene oligomerization.

[0008] CN109651436A reports an ionic liquid, an ionic liquid-supported nickel catalyst, and a method for catalyzing the oligomerization of n-butene or mixed C4 compounds. After the reaction, the catalyst and product separate into layers, allowing for direct separation. The catalyst's activity does not significantly decrease with repeated recycling, greatly reducing catalyst costs and waste generation. CN112851457A reports a chemically immobilized Brøsted acidic ionic liquid-catalyzed method for converting low-carbon olefins to isooctene. Using protonated N-heterocyclic modified sulfonate amphoteric salt resin particles as the catalyst, the isobutene conversion rate reaches up to 99%, and the selectivity for dimerization products reaches up to 85%. The catalyst can be recycled up to 5 times while maintaining essentially the same activity and selectivity. CN110227543A reports an ionic liquid-supported transition metal catalyst, its preparation, and its application in olefin oligomerization. Using a sulfonic acid-functionalized tetranuclear ionic liquid-supported transition metal as a catalyst, and propylene, 1-butene, 2-butene, isobutene, 1-pentene, etc. as raw materials, olefin oligomers are synthesized at a reaction temperature of 100~120 ℃ and a reaction pressure of 0.5~4 MPa.

[0009] Therefore, in the oligomerization reaction of low-carbon olefins, solid phosphoric acid catalysts mainly produce dimer gasoline components with low trimer selectivity, and suffer from disadvantages such as low mechanical strength, easy mud formation, and non-renewability. Molecular sieve catalysts and oxide catalysts have the advantages of high catalytic activity, adjustable acid strength, no corrosion, no pollution, strong resistance to poisoning, and renewability. Therefore, molecular sieves and oxides with suitable pore structures and acidity have good catalytic performance for the oligomerization reaction of isobutylene. Acidic cation exchange resin catalysts have the characteristics of high acidity, stable catalytic effect, mild reaction conditions, and single product, but they are difficult to regenerate, have poor heat resistance, and have expensive raw materials. Ionic liquids are usually synthesized from metal halide salts with L-acids and organic halide salts. Because they possess both the non-volatility of solid acids and the high-density reactivity of liquid acids, their structure and acidity can be flexibly adjusted. However, the preparation process is complex and expensive, and large-scale industrial application is still some distance away.

[0010] In summary, developing molecular sieve catalysts with suitable pore structures and acidity for the oligomerization of low-carbon olefins, achieving high yields and high catalyst stability in the C8-C16 jet fuel segment, is of great significance for the industrial application of the SAF process in the ATJ route. Summary of the Invention

[0011] To address the aforementioned shortcomings, the present invention aims to propose a method for preparing an olefin oligomerization catalyst, thereby solving the problem that existing catalysts cannot simultaneously achieve high yields of olefins in the C8-C16 jet fuel stage and high catalyst stability.

[0012] To achieve this objective, the present invention adopts the following technical solution: A method for preparing an olefin oligomerization catalyst includes the following steps: S1. Add the zeolite molecular sieve to the acid solution, stir at 60~100℃ for 1~24 hours, filter, wash until neutral, and dry to obtain a multi-level porous molecular sieve; S2. Add the hierarchical porous molecular sieve to a salt solution containing polyvalent metal cations, stir at 25~100 ℃ for 1~12 hours, filter, wash until neutral, dry, and calcine at 400~600 ℃ for 4~12 hours to obtain an olefin oligomerization catalyst. The SiO2 / Al2O3 molar ratio of the zeolite molecular sieve is 5-30, and the mass percentage of polyvalent metal cations in the prepared olefin oligomerization catalyst is less than 1%, while the mass percentages of Na ions and K ions are both less than 0.1%.

[0013] Preferably, the zeolite molecules are selected from one or two of FAU, MFI, MOR, FER, BEA, MAZ, EUR, and MWW.

[0014] Preferably, the acid solution is a solution of nitric acid, hydrochloric acid, sulfuric acid, oxalic acid, or citric acid.

[0015] Preferably, the concentration of the acid solution is 0.1~1 mol / L.

[0016] Preferably, the multi-level porous molecular sieve contains both microporous and mesoporous structures.

[0017] Preferably, the metal element of the polyvalent metal cation is selected from one or two of Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, and Zn.

[0018] Preferably, the valence state of the multivalent metal cation is 2 or higher.

[0019] Preferably, the salt in the salt solution is selected from one or two of nitrates, sulfates, chlorides, and organometallic salts.

[0020] Preferably, the concentration of the salt solution is 0.1~2 mol / L.

[0021] Preferably, the prepared olefin oligomerization catalyst is used in the oligomerization reaction of C3-C4 low-carbon olefins to prepare C8-C16 aviation fuel olefins. The oligomerization reaction is carried out in a fixed-bed reactor at a reaction temperature of 80-150°C, a reaction pressure of 2.0-4.0 MPa, and a liquid hourly space velocity (LHSV) of 1-6.0 h⁻¹ for the low-carbon olefins. -1 .

[0022] The technical solution provided by this invention may include the following beneficial effects: 1. A secondary pore-forming process is performed on zeolite molecular sieves using an acid solution to obtain a hierarchical porous molecular sieve with a large specific surface area, uniform pore size distribution, and containing both micropores and mesopores. Then, ion exchange is used to remove K+ from the hierarchical porous molecular sieve. + Or Na + After exchange with multivalent metal cations, a modified hierarchical porous solid acid catalyst (olefin oligomerization catalyst) is obtained. Compared with traditional zeolite catalysts, the catalyst prepared in this invention retains the acid centers and shape-selective characteristics of the microporous structure, and the presence of mesopores improves the diffusion and transport performance of guest molecules in the pores. At the same time, the multivalent cations can precisely control the acid centers of the molecular sieve, resulting in high activity, high selectivity, and good stability.

[0023] 2. The olefin oligomerization catalyst prepared by this invention exhibits excellent catalytic performance in the preparation of C8-C16 aviation fuel olefins from the oligomerization reaction of C3-C4 low-carbon olefins, with an olefin conversion rate of greater than 95% and a C8-C16 aviation fuel olefin yield of greater than 90%, showing good prospects for industrial application. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the hierarchical porous M-USY molecular sieve prepared in Example 3 of the present invention, which clearly shows the formed mesoporous structure.

[0025] Figure 2 The image shown is a transmission electron microscope (TEM) image of the hierarchical porous M-USY molecular sieve prepared in Example 3 of this invention, which clearly shows the uncollapsed microporous structure.

[0026] Figure 3 This is a compositional element distribution diagram of the Fe / M-USY olefin oligomerization catalyst prepared in Example 3 of the present invention. It can be seen that after Fe ion exchange, the Fe element is evenly distributed in the molecular sieve, and no obvious large particles are observed, so the pores of the molecular sieve are not blocked. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0028] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] A method for preparing an olefin oligomerization catalyst includes the following steps: S1. Add the zeolite molecular sieve to the acid solution, stir at 60~100℃ for 1~24 hours, filter, wash until neutral, and dry to obtain a multi-level porous molecular sieve; S2. Add the hierarchical porous molecular sieve to a salt solution containing polyvalent metal cations, stir at 25~100 ℃ for 1~12 hours, filter, wash until neutral, dry, and calcine at 400~600 ℃ for 4~12 hours to obtain an olefin oligomerization catalyst. The SiO2 / Al2O3 molar ratio of the zeolite molecular sieve is 5-30, and the mass percentage of polyvalent metal cations in the prepared olefin oligomerization catalyst is less than 1%, while the mass percentages of Na ions and K ions are both less than 0.1%.

[0031] A secondary pore-forming process using acid solutions was employed to create hierarchical porous molecular sieves with large specific surface area, uniform pore size distribution, and the presence of both micropores and mesopores. (Reference) Figure 1 and Figure 2 Then, ion exchange was used to remove K from the hierarchical porous molecular sieve. + Or Na + Modified hierarchical porous solid acid catalysts (olefin oligomerization catalysts) were obtained by exchanging polyvalent metal cations. (Reference) Figure 3 Compared to traditional zeolite catalysts, the catalyst prepared in this invention retains the acid centers and shape-selective characteristics of the microporous structure. Furthermore, the presence of mesopores enhances the diffusion and transport performance of guest molecules within the pores. Simultaneously, the polyvalent cations can precisely control the acid centers of the molecular sieve, resulting in high activity, high selectivity, and good stability.

[0032] This invention obtains a multi-level porous system by acid washing zeolite molecular sieves, containing micropores smaller than 2 nanometers and mesopores ranging from 2 to 50 nanometers. The microporous structure retains the acid centers and shape-selective characteristics of zeolite molecular sieves, providing active centers and reaction sites for reactants, while the mesoporous structure provides sufficient diffusion channels for reactants and products. This multi-level porous molecular sieve not only possesses the high diffusion of mesoporous materials and the high activity of zeolite molecular sieves, but also avoids the shortcomings of both, truly leveraging the advantages of each level of the porous structure.

[0033] K in multi-level porous molecular sieves+ Or Na + After being exchanged with polyvalent metal cations, the adsorbed water or crystal water contained in the zeolite can form hydrated ions with the polyvalent metal cations. As the water is dried and lost to a certain extent, the polarization effect of the polyvalent metal cations on water molecules gradually increases, eventually dissociating into H+. + The process generates Brønsted acid centers, which can then be dehydrated to produce Lewis acid centers. Through this preparation method, the type, concentration, and intensity of acid centers in the zeolite molecular sieve can be precisely controlled, thereby improving catalytic activity and product selectivity. The prepared olefin oligomerization catalyst exhibits high catalytic activity, good selectivity, and long lifespan.

[0034] In the preparation process, step S1 selects the stirring temperature and time based on the original pore size of the zeolite molecular sieve. The smaller the original pore size of the zeolite molecular sieve, the higher the stirring temperature and the longer the stirring time. Step S2 selects the stirring temperature and time based on the original pore size of the zeolite molecular sieve and the ionic radius of the polyvalent metal cations. The smaller the original pore size of the zeolite molecular sieve and the larger the radius of the polyvalent metal cations, the higher the stirring temperature and the longer the stirring time. Step S2 also selects the calcination temperature and time based on the original pore size of the zeolite molecular sieve. The smaller the original pore size of the zeolite molecular sieve, the higher the calcination temperature and the longer the calcination time.

[0035] Preferably, the zeolite molecules are selected from one or two of FAU, MFI, MOR, FER, BEA, MAZ, EUR, and MWW.

[0036] Preferably, the zeolite molecules are selected from one or two of FAU, MFI, FER, and BEA.

[0037] These zeolite molecular sieves all possess a maximum ten- or twelve-membered ring channel system with large pore sizes, making them prone to forming hierarchical channel structures after acid hydrolysis. Furthermore, due to the difference in pore dimension, combining two types of zeolite molecular sieves is more conducive to mass transfer.

[0038] Preferably, the acid solution is a solution of nitric acid, hydrochloric acid, sulfuric acid, oxalic acid, or citric acid.

[0039] The selected acid solutions can be removed during the subsequent calcination process, leaving no residue. Moreover, they are all commonly used industrial acids, which are low in cost and readily available.

[0040] Preferably, the concentration of the acid solution is 0.1~1 mol / L.

[0041] Preferably, the concentration of the acid solution is 0.1~0.5 mol / L; more preferably 0.3 mol / L.

[0042] When the concentration of the acid solution is too high, the zeolite molecular sieve will be excessively corroded, resulting in excessively large pores and possible structural collapse.

[0043] Preferably, the multi-level porous molecular sieve contains both microporous and mesoporous structures.

[0044] Preferably, the metal element of the polyvalent metal cation is selected from one or two of Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, and Zn.

[0045] Preferably, the metal element of the polyvalent metal cation is selected from one or two of the elements Mn, Fe, Co, Ni, Cu, and Zn.

[0046] These metal elements have moderate atomic sizes, making them easy to exchange with K or Na ions in the molecular sieve. Furthermore, the selected metal elements are mostly in transition states, and their electronic structures are easily adjustable, facilitating the control of acidic sites on the molecular sieve surface. Using two metal elements simultaneously allows their electronic structures to influence each other, further facilitating the control of the material's surface electronic states. However, if three or more metal elements are used simultaneously, one of them may precipitate, which is detrimental to electronic control and increases process complexity.

[0047] Preferably, the valence state of the multivalent metal cation is 2 or higher.

[0048] Preferably, the salt in the salt solution is selected from one or two of nitrates, sulfates, chlorides, and organometallic salts.

[0049] Preferably, the salt in the salt solution is selected from one or two of nitrates and chlorides.

[0050] The selected salts have their anions removed during the later calcination process, leaving no residue. Moreover, they are all industrial common metal salts, which are low in cost and readily available.

[0051] Preferably, the concentration of the salt solution is 0.1~2 mol / L.

[0052] Preferably, the concentration of the salt solution is 0.1~1 mol / L.

[0053] When the concentration of the salt solution is too high, some of the solution will accumulate locally in the molecular sieve channels. During subsequent calcination, oxide particles are easily generated, which can block the channels and affect mass transfer.

[0054] Preferably, the prepared olefin oligomerization catalyst is used in the oligomerization reaction of C3-C4 low-carbon olefins to prepare C8-C16 aviation fuel olefins. The oligomerization reaction is carried out in a fixed-bed reactor at a reaction temperature of 80-150°C, a reaction pressure of 2.0-4.0 MPa, and a liquid hourly space velocity (LHSV) of 1-6.0 h⁻¹ for the low-carbon olefins. -1 .

[0055] The olefin oligomerization catalyst prepared by this invention exhibits excellent catalytic performance in the preparation of C8-C16 aviation fuel olefins from the oligomerization reaction of C3-C4 low-carbon olefins. The olefin conversion rate is greater than 95%, and the yield of C8-C16 aviation fuel olefins is greater than 90%, showing good prospects for industrial application.

[0056] The oligomerization reaction occurs at low temperatures, with liquid hourly space velocities (LHSVs) of 1–6.0 h⁻¹ for low-carbon olefins. -1 It boasts a large throughput and high adjustability. This is due to the hierarchical porous structure of the olefin oligomerization catalyst, which contains both mesopores and micropores, facilitating mass transfer of reactants. Furthermore, the presence of polyvalent metal cations can adjust the acidity or basicity of the catalyst surface, thereby enhancing catalytic activity.

[0057] Example 1: Preparation of Mn / MY catalyst for olefin oligomerization In this embodiment, Y-type molecular sieves from the FAU structural type are selected to prepare hierarchical porous MY molecular sieves, with Mn 2+ The preparation of the olefin oligomerization catalyst Mn / MY after exchange includes the following steps: (1) Add 5g of Y molecular sieve with a SiO2 / Al2O3 molar ratio of 5~12 to 50 mL of 0.3 mol / L citric acid solution and stir vigorously at 80℃ for 4 h. Filter and wash the resulting white molecular sieve slurry until neutral, and dry it in an oven at 120℃ for 12 h to obtain hierarchical porous MY molecular sieve; (2) The multi-level porous MY molecular sieve obtained in step 1 was added to a 1 mol / L aqueous solution of manganese nitrate Mn(NO3)2 and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Mn / MY.

[0058] Example 2: Preparation of Ni / MY catalyst for olefin oligomerization In this embodiment, Y-type molecular sieves from the FAU structure type are selected to prepare hierarchical porous MY molecular sieves, with Ni 2+ The preparation of the olefin oligomerization catalyst Ni / MY after exchange includes the following steps: (1) Add 5g of Y molecular sieve with a SiO2 / Al2O3 molar ratio of 5~12 to 50 mL of 0.3 mol / L citric acid solution and stir vigorously at 80℃ for 4 h. Filter and wash the resulting white molecular sieve slurry until neutral, and dry it in an oven at 120℃ for 12 h to obtain hierarchical porous MY molecular sieve; (2) The multi-level porous MY molecular sieve obtained in step 1 was added to a 1 mol / L nickel nitrate Ni(NO3)2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Ni / MY.

[0059] Example 3: Preparation of the olefin oligomerization catalyst Fe / M-USY In this embodiment, a hierarchical porous M-USY molecular sieve was prepared using USY molecular sieve from the FAU structural type, with Fe 2+ The preparation of the olefin oligomerization catalyst Fe / M-USY after exchange includes the following steps: (1) 5g of USY molecular sieve with a SiO2 / Al2O3 molar ratio of 13~17 was added to 50 mL of 0.2 mol / L citric acid solution and stirred vigorously at 80℃ for 4 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-USY molecular sieve; (2) The multi-level porous M-USY molecular sieve obtained in step 1 was added to a 1 mol / L ferrous chloride FeCl2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Fe / M-USY.

[0060] Example 4: Preparation of Zn / M-USY olefin oligomerization catalyst In this embodiment, USY molecular sieves of the FAU structural type are selected to prepare hierarchical porous M-USY molecular sieves, with Zn 2+ The preparation of the olefin oligomerization catalyst Zn / M-USY after exchange includes the following steps: (1) 5g of USY molecular sieve with a SiO2 / Al2O3 molar ratio of 13~17 was added to 50 mL of 0.2 mol / L citric acid solution and stirred vigorously at 80℃ for 4 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-USY molecular sieve; (2) The multi-level porous M-USY molecular sieve obtained in step 1 was added to a 1 mol / L zinc nitrate Zn(NO3)2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Zn / M-USY.

[0061] Example 5: Preparation of olefin oligomerization catalyst Fe / M-ZSM-35 In this embodiment, ZSM-35 molecular sieve of the FER structure type was selected to prepare hierarchical porous M-ZSM-35 molecular sieve, with Fe 2+ The preparation of the olefin oligomerization catalyst Fe / M-ZSM-35 after exchange includes the following steps: (1) 5g of ZSM-35 molecular sieve with a SiO2 / Al2O3 molar ratio of 25 was added to 50 mL of 0.1 mol / L oxalic acid solution and stirred vigorously at 70℃ for 2 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-ZSM-35 molecular sieve; (2) The multi-level porous M-ZSM-35 molecular sieve obtained in step 1 was added to a 1 mol / L ferrous chloride FeCl2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Fe / M-ZSM-35.

[0062] Example 6: Preparation of Ni / M-ZSM-35 olefin oligomerization catalyst In this embodiment, ZSM-35 molecular sieve from the FER structure type is selected to prepare hierarchical porous M-ZSM-35 molecular sieve, with Ni 2+ The preparation of the olefin oligomerization catalyst Ni / M-ZSM-35 after exchange includes the following steps: (1) 5g of ZSM-35 molecular sieve with a SiO2 / Al2O3 molar ratio of 25 was added to 50 mL of 0.1 mol / L oxalic acid solution and stirred vigorously at 70℃ for 2 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-ZSM-35 molecular sieve; (2) The multi-level porous M-ZSM-35 molecular sieve obtained in step 1 was added to a 2 mol / L nickel nitrate Ni(NO3)2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Ni / M-ZSM-35.

[0063] Example 7: Preparation of Zn / M-ZSM-5 olefin oligomerization catalyst In this embodiment, ZSM-5 molecular sieves of the MFI structural type were selected to prepare hierarchical porous M-ZSM-5 molecular sieves, with Zn 2+ The preparation of the olefin oligomerization catalyst Zn / M-ZSM-5 after exchange includes the following steps: (1) 5g of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 18 was added to 50 mL of 0.5 mol / L hydrochloric acid solution and stirred vigorously at 70℃ for 6 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-ZSM-5 molecular sieve; (2) The multi-level porous M-ZSM-5 molecular sieve obtained in step 1 was added to a 2 mol / L zinc nitrate Zn(NO3)2 aqueous solution and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 h, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Zn / M-ZSM-5.

[0064] Example 8: Preparation of the olefin oligomerization catalyst Co / M-ZSM-5 In this embodiment, ZSM-5 molecular sieves of the MFI structural type were selected to prepare hierarchical porous M-ZSM-5 molecular sieves, with Zn 2+ The preparation of the olefin oligomerization catalyst Zn / M-ZSM-5 after exchange includes the following steps: (1) 5g of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 18 was added to 50 mL of 0.5 mol / L hydrochloric acid solution and stirred vigorously at 70℃ for 6 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-ZSM-5 molecular sieve; (2) The hierarchical porous M-ZSM-5 molecular sieve obtained in step 1 was added to a 2 mol / L cobalt nitrate Co(NO3)2 aqueous solution and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Co / M-ZSM-5.

[0065] Example 9: Preparation of CoNi / M-ZSM-5 olefin oligomerization catalyst In this embodiment, ZSM-5 molecular sieves from the MFI structural type were selected to prepare hierarchical porous M-ZSM-5 molecular sieves, with Co 2+ and Ni 2+ The preparation of the olefin oligomerization catalyst CoNi / M-ZSM-5 after exchange includes the following steps: (1) 5g of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 18 was added to 50 mL of 0.5 mol / L hydrochloric acid solution and stirred vigorously at 70℃ for 6 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical porous M-ZSM-5 molecular sieve; (2) The hierarchical porous M-ZSM-5 molecular sieve obtained in step 1 was added to a 2 mol / L aqueous solution of cobalt nitrate Co(NO3)2 and nickel nitrate Ni(NO3)2 and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried and dried in an oven at 120 °C for 12 hours. It was then calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst CoNi / M-ZSM-5.

[0066] Example 10: Preparation of Fe / M-β olefin oligomerization catalyst In this embodiment, a hierarchical porous M-β molecular sieve was prepared using β-zeolite from the BEA structural type, with Fe 2+ The preparation of the Fe / M-β olefin oligomerization catalyst after exchange includes the following steps: (1) 5g of β molecular sieve with a SiO2 / Al2O3 molar ratio of 20 was added to 50 mL of 0.2 mol / L oxalic acid solution and stirred vigorously at 90℃ for 4 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical M-β molecular sieve; (2) The hierarchical porous M-β molecular sieve obtained in step 1 was added to a 1 mol / L ferrous chloride FeCl2 aqueous solution and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Fe / M-β.

[0067] Example 11: Preparation of CoNi / M-β olefin oligomerization catalyst In this embodiment, a hierarchical porous M-β molecular sieve was prepared using β-zeolite from the BEA structural type, with Co... 2+ and Ni 2+ The preparation of the olefin oligomerization catalyst CoNi / M-β after exchange includes the following steps: (1) 5g of β molecular sieve with a SiO2 / Al2O3 molar ratio of 20 was added to 50 mL of 0.2 mol / L oxalic acid solution and stirred vigorously at 90℃ for 4 h. The resulting white molecular sieve slurry was filtered, washed until neutral, and dried in an oven at 120℃ for 12 h to obtain hierarchical M-β molecular sieve; (2) The hierarchical porous M-β molecular sieve obtained in step 1 was added to a 2 mol / L aqueous solution of cobalt nitrate Co(NO3)2 and nickel nitrate Ni(NO3)2 and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried and dried in an oven at 120 °C for 12 hours. It was then calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst CoNi / M-β.

[0068] Comparative Example 1: USY Molecular Sieves This comparative example uses USY molecular sieves with a SiO2 / Al2O3 molar ratio of 13-17 in the FAU structure type, which are calcined in a muffle furnace at 550 °C for 5 hours for comparison.

[0069] Comparative Example 2, Zn / USY Molecular Sieves This comparative example selects USY molecular sieve from the FAU structural type, with Zn 2+ The preparation of Zn / USY molecular sieves after exchange includes the following steps: (1) 5g of USY molecular sieve with a SiO2 / Al2O3 molar ratio of 13~17 was calcined in a muffle furnace at 550 ℃ for 5 hours; (2) The USY molecular sieve obtained in step 1 was added to a 1 mol / L zinc nitrate Zn(NO3)2 aqueous solution and stirred at 90 °C for 10 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Zn / USY.

[0070] Comparative Example 3, β-zeolite This comparative example uses a β molecular sieve with a SiO2 / Al2O3 molar ratio of 20 from the BEA structure type, which is calcined in a muffle furnace at 550 °C for 5 hours for comparison.

[0071] Comparative Example 4, Fe / β Molecular Sieves This embodiment selects β-zeolite from the BEA structural type, with Fe 2+ The preparation of Fe / β molecular sieves after exchange includes the following steps: (1) 5g of β molecular sieve with a SiO2 / Al2O3 molar ratio of 20 was calcined in a muffle furnace at 550 ℃ for 5 hours; (2) The β molecular sieve obtained in step 1 was added to a 1 mol / L ferrous chloride FeCl2 aqueous solution and stirred at 80 °C for 12 hours. The slurry was filtered, washed until neutral, dried, dried in an oven at 120 °C for 12 hours, and calcined in a muffle furnace at 550 °C for 5 hours to obtain the olefin oligomerization catalyst Fe / β.

[0072] Example 12: Evaluation of Catalyst Performance The catalytic performance of the catalysts for the oligomerization of low-carbon olefins was evaluated by testing the conversion rate of the olefin oligomerization catalysts prepared in Examples 1-11 and the molecular sieves prepared in Comparative Examples 1-4 in the C3-C4 low-carbon olefin oligomerization reaction and the C8-C16 olefin yield in the jet fuel stage. Low-carbon olefin conversion rate (%) =

[0073] Olefin yield in jet fuel section (%) =

[0074] The catalytic activity of the catalysts prepared in Examples 1-11 for the oligomerization of low-carbon olefins was evaluated in a stainless steel fixed-bed reactor with an inner diameter of 8 mm. The evaluation conditions were: catalyst loading of 1.0 g, reaction temperature of 1200 °C, and weight hourly space velocity of 4 h⁻¹. -1 The molar ratio of low-carbon olefins to nitrogen is 1:1, and the reaction pressure is 3 MPa. The specific evaluation method is as follows: 1 g of catalyst (40-60 mesh) was mixed thoroughly with 2 g of quartz sand and loaded into the isothermal section of a fixed-bed reactor. The mixture was then activated for 6 h in a N2 atmosphere at 350 ℃, 3.0 MPa, and 20 ml / min. At 120 ℃ and 3.0 MPa, nitrogen and low-carbon olefins were introduced into the evaporator via a mass flow meter and a high-performance liquid chromatography constant flow pump, respectively. After thorough mixing in a gas mixer, the mixture was introduced into the reactor for reaction, with the weight time space velocity controlled at 4 h⁻¹. -1 The outlet gas stream was sampled using an automated six-way valve system, and then quantitatively analyzed using an online gas chromatograph. The detector was a flame ionization detector (FID), and the chromatographic column was an HP-PLOT Q capillary column (30 m × 0.53 mm × 40 μm) with an interval of 1 h. The conversion rate (%) of low-carbon olefins and the yield (%) of C8–C16 olefins in the jet fuel section were calculated, as shown in Table 1.

[0075] Table 1. Catalytic performance evaluation results of the catalyst

[0076] As can be seen from the results in Table 1, the olefin oligomerization catalyst of the present invention has a high conversion rate of low-carbon olefins, reaching almost 99% at its highest, and a C8~C16 olefin yield of more than 90% in the jet fuel section, reaching up to 93.1% at its highest.

[0077] In summary, the olefin oligomerization catalyst prepared by this method has simple operation steps, excellent catalytic activity, and high yield of the target product. It is conducive to the industrial application of low-carbon olefin oligomerization to produce olefins in aviation kerosene and has a very good prospect for industrial application.

[0078] Example 12: Catalyst Stability Evaluation The stability of the Zn / M-USY catalyst prepared in Example 4 and the CoNi / M-β catalyst prepared in Example 11 was evaluated according to the catalytic performance test method of Example 12. The results of low-carbon olefin conversion (%) and C8~C16 olefin yield (%) in the jet fuel section are shown in Tables 2 and 3. Table 2. Stability evaluation of Zn / M-USY catalyst

[0079] As shown in Table 2, the Zn / M-USY catalyst prepared in Example 4 maintained a low-carbon olefin conversion rate of over 97% and a C8-C16 olefin yield of over 90% in the jet fuel stage after a 240-h reaction evaluation. These results indicate that the Zn / M-USY catalyst prepared in Example 4 possesses good stability.

[0080] Table 3. Stability evaluation of CoNi / M-β catalyst

[0081] As shown in Table 3, the CoNi / M-β catalyst prepared in Example 11 maintained a low-carbon olefin conversion rate of over 95% and a C8-C16 olefin yield of over 90% in the jet fuel section after a 240-h reaction evaluation. These results indicate that the CoNi / M-β catalyst prepared in Example 11 possesses good stability.

[0082] As can be seen from the above stability tests, the olefin oligomerization catalyst prepared by the present invention has good catalytic stability, long catalyst life, and reduced catalyst usage cost, which is conducive to industrial promotion.

[0083] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing an olefin oligomerization catalyst, characterized in that, Includes the following steps: S1. Add the zeolite molecular sieve to the acid solution, stir at 60~100℃ for 1~24 hours, filter, wash until neutral, and dry to obtain a multi-level porous molecular sieve; S2. Add the hierarchical porous molecular sieve to a salt solution containing polyvalent metal cations, stir at 25~100 ℃ for 1~12 hours, filter, wash until neutral, dry, and calcine at 400~600 ℃ for 4~12 hours to obtain an olefin oligomerization catalyst. The SiO2 / Al2O3 molar ratio of the zeolite molecular sieve is 5-30, and the mass percentage of polyvalent metal cations in the prepared olefin oligomerization catalyst is less than 1%, while the mass percentages of Na ions and K ions are both less than 0.1%.

2. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The zeolite molecules are selected from one or two of FAU, MFI, MOR, FER, BEA, MAZ, EUR, and MWW.

3. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The acid solution is a solution of nitric acid, hydrochloric acid, sulfuric acid, oxalic acid, or citric acid.

4. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The concentration of the acid solution is 0.1~1 mol / L.

5. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The multi-level porous molecular sieve contains both microporous and mesoporous structures.

6. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The metal element of the polyvalent metal cation is selected from one or two of Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, and Zn.

7. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The valence state of the polyvalent metal cation is 2 or higher.

8. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The salt in the salt solution is selected from one or two of nitrates, sulfates, chlorides, and organometallic salts.

9. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The concentration of the salt solution is 0.1~2 mol / L.

10. The method for preparing an olefin oligomerization catalyst according to claim 1, characterized in that: The prepared olefin oligomerization catalyst was applied to the oligomerization reaction of C3-C4 low-carbon olefins to prepare C8-C16 aviation fuel olefins. The oligomerization reaction was carried out in a fixed-bed reactor at a reaction temperature of 80-150℃, a reaction pressure of 2.0-4.0 MPa, and a liquid hourly space velocity (LHSV) of 1-6.0 h⁻¹ for the low-carbon olefins. -1 .

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