Molecular sieve supported metal catalyst as well as preparation method and application thereof

Abstract

The invention provides a molecular sieve supported metal catalyst as well as a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: taking a mixed solution containing a metal precursor, a hydroxide organic amine template agent and water as an impregnation liquid, impregnating a molecular sieve in the impregnation liquid under a heating condition, and obtaining a mixture after impregnation is completed; and at least drying, roasting and reducing the mixture to obtain the molecular sieve supported metal catalyst. The molecular sieve supported metal catalyst provided by the invention is prepared by the method. The invention also provides application of the molecular sieve supported metal catalyst as a catalyst in alkane hydroisomerization reaction and / or biolipid hydrodeoxygenation reaction. The metal dispersity in the catalyst is improved, and the catalytic performance of the catalyst in alkane hydroisomerization reaction and biolipid hydrodeoxygenation reaction is improved.

Description

Technical Field

[0001] The present invention relates to a molecular sieve supported metal catalyst, a preparation method thereof and an application thereof, and belongs to the technical field of molecular sieve catalysts. Background Art

[0002] Molecular sieve supported metal catalysts are widely used in processes such as hydrocracking, isomerization, catalytic reforming and hydrodeoxygenation of bio-oils in the refining and chemical industries. The catalytic performance of such catalysts not only depends closely on the properties of the support, but also largely depends on the type and properties of the metal components. Among them, noble metal catalysts often have high activity and selectivity, but they are expensive and easily poisoned and deactivated. Using non-noble metals to replace noble metal catalysts has always been a research hotspot in this field. However, the activity of non-noble metal catalysts is lower than that of noble metals. Increasing the loading amount is an important way to improve their activity, but a higher loading amount will lead to serious aggregation of metals, reducing the catalyst activity and metal utilization rate. Therefore, improving the metal dispersion is the key to obtaining highly efficient non-noble metal catalysts.

[0003] The impregnation method is a commonly used method for preparing metal supported catalysts. This method is widely used in the industrial production of supported metal catalysts because of its simple process, easy operation and easy control of the metal loading amount. However, the catalysts prepared by the impregnation method often have the problem of low metal dispersion, especially for non-noble metal catalysts with a high loading amount. This is mainly because when preparing the catalyst by the impregnation method, it is difficult to form a strong interaction between the metal and the support, resulting in the aggregation and growth of metal species during the high-temperature treatment process, reducing the metal dispersion; even when using porous materials such as molecular sieves as the support, it is often due to the difficulty of metal species entering the support pores and the migration of metal species at high temperature, resulting in a very limited confinement effect of the support pores on the metal species, and it is difficult to prepare a supported metal catalyst with high metal dispersion. In view of this, relevant scholars have tried to improve the metal-support interaction by using impregnation solvents with low polarity, enhance the confinement effect of the pores on the metal by pretreating the support to expose its pore structure, or use the protective effect of organic ligands on the metal species to inhibit the aggregation of metal species, thereby improving the metal dispersion of the impregnation method catalyst. Although the above methods can improve the activity of the catalyst to a certain extent, they also make the catalyst preparation process complicated or the metal dispersion still needs to be further improved.

[0004] Therefore, developing a preparation method for a molecular sieve supported metal catalyst with a simple process, easy operation and effective improvement of metal dispersion has become one of the urgent problems to be solved in this field. Summary of the Invention

[0005] To solve the above technical problems, the object of the present invention is to provide a molecular sieve-supported metal catalyst, a preparation method thereof and an application thereof. By using a hydroxide-based organic amine templating agent in the metal impregnation solution and performing impregnation under heating conditions, the present invention can improve the dispersion of the metal and has the advantages of simple process and easy operation.

[0006] To achieve the above object, in a first aspect of the present invention, a preparation method of a molecular sieve-supported metal catalyst is provided, which comprises the following steps:

[0007] (1) Using a mixed solution containing a metal precursor, a hydroxide-based organic amine templating agent and water as an impregnation solution, impregnating the molecular sieve in the impregnation solution under heating conditions, and after the impregnation is completed, obtaining a mixture;

[0008] (2) After drying, calcining and reducing the mixture at least, obtaining the molecular sieve-supported metal catalyst.

[0009] According to the specific embodiments of the present invention, preferably, in step (1), the metal precursor includes one or more of soluble nickel salts and soluble molybdenum salts, etc. More preferably, the metal precursor includes one or more of nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, ammonium molybdate, sodium molybdate and molybdenum nitrate, etc.

[0010] According to the specific embodiments of the present invention, preferably, in step (1), the hydroxide-based organic amine templating agent includes a compound having the structure shown in Formula I:

[0011]

[0012] In Formula I, R 1 , R 2 , R 3 and R 4 each independently selected from one of aliphatic hydrocarbon groups and aromatic hydrocarbon groups.

[0013] More preferably, in Formula I, R 1 , R 2 , R 3 and R 4 each independently selected from C1-C18 straight-chain or branched-chain alkyl groups. Further preferably, the hydroxide-based organic amine templating agent includes one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, etc.

[0014] According to the specific embodiments of the present invention, preferably, in step (1), the pH value of the impregnation solution is 10-14.

[0015] According to the specific embodiments of the present invention, preferably, in step (1), the silica-alumina ratio of the molecular sieve is 25 or more. More preferably, the molecular sieve includes one or more of Beta molecular sieve, ZSM-5 molecular sieve, ZSM-22 molecular sieve, S-1 molecular sieve, MOR molecular sieve, etc.

[0016] According to the specific embodiments of the present invention, preferably, in step (1), the heating temperature of the impregnation is 50 - 200 °C, and the impregnation time is 2 - 36 h.

[0017] According to the specific embodiments of the present invention, preferably, in step (1), the mass ratio of the molecular sieve to the volume of the impregnation solution is (10 - 20) g : (15 - 30) mL.

[0018] According to the specific embodiments of the present invention, preferably, in step (2), the calcination temperature is 350 - 550 °C, and the time is 2 - 6 h.

[0019] According to the specific embodiments of the present invention, preferably, in step (2), the reduction temperature is 400 - 600 °C, and the time is 2 - 6 h.

[0020] The second aspect of the present invention provides a molecular sieve-supported metal catalyst, which is prepared by the above-mentioned preparation method of the molecular sieve-supported metal catalyst; the molecular sieve-supported metal catalyst includes: a molecular sieve carrier, and a metal component supported on the molecular sieve carrier.

[0021] According to the specific embodiments of the present invention, preferably, the metal component includes nickel and / or molybdenum, etc.

[0022] According to the specific embodiments of the present invention, preferably, based on the total mass of the molecular sieve carrier being 100%, the content of the metal component in the molecular sieve-supported metal catalyst in terms of metal atoms is 2% - 10%.

[0023] According to the specific embodiments of the present invention, preferably, the average particle size of the metal component in the molecular sieve-supported metal catalyst is 4 - 15 nm.

[0024] According to the specific embodiments of the present invention, preferably, the dispersion degree of the metal component in the molecular sieve-supported metal catalyst is 6% - 25%.

[0025] The third aspect of the present invention provides the application of the above-mentioned molecular sieve-supported metal catalyst as a catalyst in the alkane hydroisomerization reaction and / or the hydrodeoxygenation reaction of biological oil.

[0026] According to the specific embodiments of the present invention, preferably, the alkane hydroisomerization reaction includes the n-hexane hydroisomerization reaction.

[0027] The present invention has at least the following beneficial effects:

[0028] (1) By using a hydroxide-based organic amine template agent in the metal impregnation solution and carrying out impregnation under heating conditions, the present invention promotes the formation of layered metal silicate during the impregnation process, enabling a strong interaction to form between the layered metal silicate and the molecular sieve support. As a result, during the subsequent calcination and reduction processes, the metal components are not easily aggregated, thereby improving the dispersion of the metal components in the catalyst.

[0029] (2) The preparation method of the molecular sieve-supported metal catalyst of the present invention does not require pretreatment of the support. The catalyst preparation process is simple and easy to operate, and is fully applicable to the existing industrial catalytic production process.

[0030] (3) The preparation method of the present invention prepares a non-precious metal catalyst with high metal dispersion, improves the catalytic performance of the catalyst in alkane hydroisomerization reaction and bio-oil hydrodeoxygenation reaction, and has high catalytic activity and selectivity. The catalyst of the present invention has activity and selectivity in alkane hydroisomerization reaction and bio-oil hydrodeoxygenation reaction, especially in n-hexane hydroisomerization reaction, comparable to commercial Pt-based catalysts, showing the potential to replace precious metal catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The infrared spectrum of the impregnated mixture prepared in Example 2 after drying and calcination.

[0032] Figure 2 The transmission electron micrograph of the impregnated mixture prepared in Example 2 after drying and calcination.

[0033] Figure 3 The transmission electron micrograph and the metal particle size distribution results of the Ni / Beta catalyst prepared in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0034] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the present invention will be described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0035] It should be noted that unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0036] All raw materials, reagents, instruments and equipment used in the present invention, unless otherwise specifically stated, can be obtained through market purchase or can be prepared by existing methods.

[0037] It should be understood that the terms "comprising", "including" and / or "containing", as used herein, specify the presence of the stated features, integers, steps, components or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0038] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0039] According to a specific embodiment of the first aspect of the present invention, the present invention provides a method for preparing a molecular sieve-supported metal catalyst, which comprises the following steps:

[0040] (1) Using a mixed solution containing a metal precursor, a hydroxide-based organic amine templating agent and water as an impregnating solution, impregnating the molecular sieve in the impregnating solution under heating conditions, and after the impregnation is completed, obtaining a mixture;

[0041] (2) After drying, calcining and reducing the mixture at least, obtaining the molecular sieve-supported metal catalyst.

[0042] In the present invention, during the heating impregnation process, the hydroxide-based organic amine templating agent promotes the formation of a layered metal silicate phase between the metal species and the silicon species on the surface of the molecular sieve, rather than forming a hydroxide precipitation phase. Specifically, the inventors of the present invention speculate that the molecular sieve is etched by the hydroxide ions released by the hydroxide-based organic amine templating agent, and some Si-O-Si bonds and Si-O-Al bonds of the molecular sieve are broken to form silanol groups; and the metal ions of the metal precursor form metal hydroxides with the hydroxyl groups in the alkaline environment provided by the hydroxide-based organic amine templating agent; the silanol groups and the metal hydroxides undergo hetero-condensation and / or polymerization reactions, dehydrating and condensing to form Si-O-M bonds (where M represents a metal), and the small molecules containing Si-O-M bonds formed by dehydration and condensation gradually form a layered metal silicate.

[0043] In the above process, the hydroxide-based organic amine templating agent of the present invention may mainly play the following three roles: 1. The hydroxide-based organic amine templating agent releases hydroxide ions to provide an alkaline environment, creating conditions for the formation of silanol groups and metal hydroxyl groups. 2. Under the conditions of heating and alkaline impregnation of the present invention, as described above, some Si-O-Si bonds and Si-O-Al bonds in the molecular sieve framework are broken, which will not only form silanol groups, but also some aluminum in the molecular sieve will be removed. Under alkaline conditions, aluminum exists in the form of aluminate ions, which will hinder the reaction between silicon and metal. The organic amine cations released by the hydroxide-based organic amine templating agent can interact with aluminate ions, making it easier for the metal to react with silicon. 3. The hydroxide-based organic amine templating agent also plays a role in structure guidance, which is beneficial to the formation of layered metal silicates.

[0044] A strong interaction is formed between the layered metal silicate formed by the present invention and the molecular sieve support. Specifically, due to the etching of the molecular sieve framework to form defect sites, as well as the reaction of silanol groups and metal hydroxyl groups, the layered metal silicate can be connected to the molecular sieve support through chemical bonds, thereby anchoring metal species and having a strong binding force. Moreover, due to the layered crystal structure of the layered metal silicate, its layer spacing and surface properties can be matched with the pore structure and surface properties of the molecular sieve to a certain extent. During the formation process, the layered metal silicate can partially embed or adhere to the inside or surface of the pores of the molecular sieve, increasing the contact area and interaction between the two. At the same time, the hydroxide-based organic amine templating agent has a certain adsorption and guiding effect on the surface of the molecular sieve. It can guide the growth and deposition of the layered metal silicate on the molecular sieve support, enabling the layered metal silicate to better combine with the molecular sieve support and form a closer interaction. Although not wanting to be restricted by the mechanism, the inventors of the present invention speculate that at least for the above reasons, a strong interaction force is formed between the layered metal silicate and the molecular sieve support, enabling the metal species to be better fixed, so that this fixing effect can limit the migration and aggregation of the metal species during the subsequent calcination and reduction processes, thereby improving the dispersion of the metal components in the catalyst.

[0045] In some specific embodiments, in step (1), the metal precursor includes one or more of soluble nickel salts and soluble molybdenum salts, etc., preferably including soluble nickel salts. Specifically, the metal precursor may include one or more of nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, ammonium molybdate, sodium molybdate, and molybdenum nitrate, etc., preferably including one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate, etc. The present invention does not impose special restrictions on the concentration of the metal precursor in the impregnation solution, and it can be adjusted by those skilled in the art based on the metal component content in the catalyst of the present invention. Preferably, the concentration of the metal precursor in the impregnation solution is 0.3 - 2 mol / L.

[0046] In some specific embodiments, in step (1), the hydroxide-based organic amine template includes a compound having the structure shown in Formula I:

[0047]

[0048] In Formula I, R 1 、R 2 、R 3 and R 4 are each independently selected from one of an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

[0049] Preferably, in Formula I, R 1 、R 2 、R 3 and R 4 are each independently selected from a C1-C18 straight-chain or branched-chain alkyl group; more preferably, R 1 、R 2 、R 3 and R 4 are each independently selected from a C1-C4 straight-chain alkyl group. Specifically, the hydroxide-based organic amine template may include one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. The present invention preferably uses an alkyl quaternary ammonium base template with a shorter carbon chain length (C1-C4), which can enhance the interaction between the template and aluminum and is more conducive to the formation of layered metal silicate.

[0050] In some specific embodiments, in step (1), the pH value of the impregnating solution is 10-14, preferably 12-14. The present invention does not further limit the content of the hydroxide-based organic amine template in the impregnating solution, as long as the pH value of the impregnating solution reaches the above range. If the pH value of the impregnating solution is lower than the above range, it is not conducive to the formation of layered metal silicate; if the pH value of the impregnating solution is higher than the above range, it will not only excessively damage the structure of the molecular sieve and result in insufficient acid sites of the molecular sieve, but also damage the formed layered metal silicate. By controlling the pH value of the impregnating solution within the above range, the present invention can enable the smooth formation of layered metal silicate, enable it to interact well with the molecular sieve carrier, maintain the structural integrity of the layered metal silicate well, and keep the structure of the molecular sieve from being excessively damaged, so that it retains appropriate acid sites.

[0051] In some specific embodiments, in step (1), the silica-alumina ratio of the molecular sieve is 25 or more, preferably 40 or more. Preferably, the molecular sieve includes one or more of Beta zeolite, ZSM-5 zeolite, ZSM-22 zeolite, S-1 zeolite, MOR zeolite, etc. Those skilled in the art can understand that S-1 zeolite is a pure silica zeolite with an infinite silica-alumina ratio in theory, so it can be considered that the silica-alumina ratio meets the above range. If the silica-alumina ratio of the molecular sieve is too low, there is too little silica in the molecular sieve framework, making it difficult to provide enough silica to form sufficient silanol groups, thus unable to smoothly form sufficient layered metal silicate, and making it difficult to exert the positive effect of the layered metal silicate on metal dispersion.

[0052] In some specific embodiments, in step (1), the heating temperature of the impregnation is 50 - 200 °C, preferably 80 - 180 °C, and the impregnation time is 2 - 36 h, preferably 6 - 24 h. If the heating temperature is lower than the above range, the reaction rate will be too low, resulting in the etching of the molecular sieve framework, the formation of silanol groups and metal hydroxyl groups, and the formation of layered metal silicate being too slow, resulting in insufficient amount of the formed layered metal silicate; and it will affect the diffusion of substances, making it difficult for the impregnation solution to fully enter the pores of the molecular sieve, resulting in uneven metal loading. If the heating temperature is higher than the above range, it may cause excessive damage to the structure of the molecular sieve; and it may cause the movement of metal ions to be too intense, resulting in the aggregation of the already formed metal hydroxyl groups or metal ions, thus making it difficult to form a uniform layered metal silicate. By controlling the heating temperature and time of the impregnation within the above range, the present invention can form the layered metal silicate more uniformly and fully, and make it uniformly distributed on the molecular sieve carrier and form a strong interaction with the molecular sieve carrier.

[0053] In some specific embodiments, in step (1), the mass ratio of the molecular sieve to the volume of the impregnation solution is (10 - 20) g : (15 - 30) mL.

[0054] In some specific embodiments, in step (2), before drying, roasting, and reducing the mixture, solid-liquid separation and / or washing and other steps can also be carried out according to actual situations. Solid-liquid separation and washing can both be carried out according to the conventional operations in the art, and the present invention does not impose special restrictions on them.

[0055] In some specific embodiments, in step (2), the drying temperature is 80 - 120 °C, and the time is 8 - 24 h.

[0056] In some specific embodiments, in step (2), the calcination temperature is 350 - 550 °C and the time is 2 - 6 h. The calcination atmosphere can be a conventional air atmosphere or the like.

[0057] In some specific embodiments, in step (2), the reduction temperature is 400 - 600 °C and the time is 2 - 6 h. The reduction atmosphere is a reducing atmosphere, for example, it can be an atmosphere containing hydrogen, pure hydrogen can be used, or a mixture of hydrogen - inert gas can also be used.

[0058] In the present invention, by using a hydroxide - type organic amine template agent in the metal impregnation solution and carrying out impregnation under heating conditions, the formation of layered metal silicate is promoted during the impregnation process, so that a strong interaction is formed between the layered metal silicate and the molecular sieve support. Furthermore, during the subsequent calcination and reduction processes, the metal components are not easily aggregated, thereby improving the dispersion of the metal components in the catalyst. At the same time, the present invention further controls conditions such as the heating conditions and the pH value of the impregnation solution during the impregnation process, maintains the structure of the molecular sieve from being overly damaged and retains suitable acidic sites, and makes the metal loading more uniform. Through the efficient synergy of the highly dispersed metal sites and acidic sites of the present invention, the catalyst has high catalytic activity and selectivity in the alkane hydroisomerization reaction and the hydrodeoxygenation reaction of biological oils and fats.

[0059] According to the specific embodiments of the second aspect of the present invention, the present invention provides a molecular sieve - supported metal catalyst, which is prepared by the above - mentioned preparation method of the molecular sieve - supported metal catalyst; the molecular sieve - supported metal catalyst includes: a molecular sieve support, and metal components supported on the molecular sieve support.

[0060] In some specific embodiments, the metal components include nickel and / or molybdenum, etc., and nickel is preferred.

[0061] In some specific embodiments, based on the total mass of the molecular sieve support being 100%, the content of the metal components in the molecular sieve - supported metal catalyst in terms of metal atoms is 2% - 10%, preferably 4% - 8%.

[0062] In some specific embodiments, the average particle size of the metal components in the molecular sieve - supported metal catalyst is 4 - 15 nm, preferably 4 - 10 nm.

[0063] In some specific embodiments, the dispersion of the metal components in the molecular sieve - supported metal catalyst is 6% - 25%, preferably 10% - 25%.

[0064] In some specific embodiments, the molecular sieve-supported metal catalyst includes a Ni / Beta catalyst and / or a Ni / ZSM-5 catalyst. The present invention preferably prepares a Ni / Beta catalyst and a Ni / ZSM-5 catalyst, which have more excellent catalytic activity and selectivity in the alkane hydroisomerization reaction and the hydrodeoxygenation reaction of biological oils and fats.

[0065] According to the specific embodiments of the third aspect of the present invention, the present invention provides the use of the above-mentioned molecular sieve-supported metal catalyst as a catalyst in the alkane hydroisomerization reaction and / or the hydrodeoxygenation reaction of biological oils and fats.

[0066] In some specific embodiments, the alkane hydroisomerization reaction includes the n-hexane hydroisomerization reaction.

[0067] In some specific embodiments, the reaction conditions of the n-hexane hydroisomerization reaction include: the reaction temperature is 260 - 320 °C, the reaction pressure is 1.0 - 3.0 MPa, the n-hexane volume space velocity is 0.5 - 1.5 h -1 , and the hydrogen / oil ratio (i.e., the molar ratio of hydrogen to n-hexane) is 3.0 - 5.0.

[0068] In some specific embodiments, the reaction conditions of the hydrodeoxygenation reaction of biological oils and fats include: the biological oil used is methyl laurate, the reaction temperature is 220 - 300 °C, the hydrogen pressure is 1.0 - 3.0 MPa, the catalyst / oil ratio (i.e., the mass ratio of the catalyst to the biological oil) is 0.08 - 0.15, and the reaction time is 20 - 120 min.

[0069] In some specific embodiments, the molecular sieve-supported metal catalyst for the alkane hydroisomerization reaction and the hydrodeoxygenation reaction of biological oils and fats includes a Ni / Beta catalyst and / or a Ni / ZSM-5 catalyst, preferably a Ni / Beta catalyst. In the application of the present invention, the Ni / Beta catalyst prepared by the present invention is preferably used for both the alkane hydroisomerization reaction and the hydrodeoxygenation reaction of biological oils and fats. Its high metal dispersion endows it with excellent hydrogenation / dehydrogenation activity and selectivity. Through the efficient synergy of the highly dispersed metal sites and the acidic sites, it exhibits n-hexane hydroisomerization catalytic performance comparable to that of commercial Pt-based catalysts.

[0070] The technical solutions of the present invention are specifically described below through examples. However, the present invention is not limited to these examples, and of course, various deformations can be carried out within the scope of the key points of the present invention.

[0071] Test method:

[0072] Metal component content in the catalyst: The ICP-OES test was carried out on the sample using an optima 8000 inductively coupled plasma atomic emission spectrometer from Perkin-Elmer to obtain the metal component content in the catalyst. Before the test, the sample needs to be pretreated. The pretreatment process is as follows: 375 μL of hydrochloric acid, 125 μL of nitric acid, 1500 μL of hydrofluoric acid, 1.4 g of boric acid and 10 ml of deionized water were successively added to 25 mg of the sample. After ultrasonic dissolution, it was placed in a 50 ml volumetric flask and made up to the mark.

[0073] Average particle size of the metal component in the catalyst: The particle size of the metal component in the catalyst was analyzed using a Talos F200X transmission electron microscope (TEM) from ThermoFisher. The electron gun is a thermal field emission super bright type, and the acceleration voltage is 20 kV - 200 kV.

[0074] Dispersion of the metal component in the catalyst: The hydrogen temperature-programmed desorption (H 2 -TPD) test was carried out on the sample using an ASAP 2020 chemisorption instrument from Micromeritics to obtain the dispersion of the metal component in the catalyst. Before the test, the sample was purged in a helium atmosphere for 1 h. After cooling to room temperature, hydrogen was introduced to saturate the adsorption. Finally, the temperature-programmed desorption was carried out at a heating rate of 10 °C / min, and the hydrogen desorption peak was detected by a TCD detector. The dispersion of the metal component was calculated as follows: The H 2 -TPD curve obtained from the test was integrated to obtain the total amount of desorbed H 2 , denoted as n H2 ; The amount of substance of the metal in the catalyst was calculated from the carrier mass, metal component content and molar mass of the metal, denoted as n M ; The dispersion D of the metal component was calculated by the following formula: D = 2n H2 ÷n M ×100%, where the units of n H2 and n M should be the same, for example, both are mol.

[0075] Example 1

[0076] This example provides a molecular sieve-supported metal catalyst, and its preparation method includes the following steps:

[0077] 1.10 g of ammonium molybdate tetrahydrate was dissolved in 20 mL of deionized water, and then tetramethylammonium hydroxide was added and stirred evenly to obtain an impregnation solution with a pH value of 13; then 10 g of Beta molecular sieve (the silica-alumina ratio is 50, the micropore volume is 0.18 cm 3 ·g -1 , the mesopore volume is 0.23 cm 3 ·g-1 ) It was added to the above-mentioned impregnation solution and stirred evenly, then transferred to a sealed container and left to stand and impregnate in an oven at 120 °C for 12 h; the impregnated mixture was dried at 100 °C for 14 h, then calcined in an air atmosphere at 450 °C for 4 h, and then reduced in a pure hydrogen atmosphere at 450 °C for 4 h to obtain the Mo / Beta catalyst.

[0078] The Mo / Beta catalyst includes a Beta zeolite support and Mo supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Mo in the Mo / Beta catalyst is 6% in terms of atoms. The average particle size of Mo in the Mo / Beta catalyst is 8.3 nm, and the dispersion of Mo is 12.0%.

[0079] Example 2

[0080] This example provides a molecular sieve-supported metal catalyst, and its preparation method includes the following steps:

[0081] 1.98 g of nickel nitrate hexahydrate was dissolved in 15 mL of deionized water, then tetraethylammonium hydroxide was added and stirred evenly to obtain an impregnation solution with a pH value of 14; then 10 g of Beta zeolite (with a silica-alumina ratio of 50 and a micropore volume of 0.18 cm 3 ·g -1 , and a mesopore volume of 0.23 cm 3 ·g -1 ) was added to the above-mentioned impregnation solution and stirred evenly, then transferred to a sealed container and left to stand and impregnate in an oven at 80 °C for 12 h; the impregnated mixture was dried at 100 °C for 14 h, then calcined in an air atmosphere at 400 °C for 4 h, and then reduced in a pure hydrogen atmosphere at 550 °C for 2 h to obtain the Ni / Beta catalyst.

[0082] The Ni / Beta catalyst includes a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / Beta catalyst is 4.2 nm, and the dispersion of Ni is 23.8%.

[0083] After the impregnated mixture in this example was dried and calcined under the above conditions, Fourier transform infrared spectroscopy was performed, and the obtained infrared spectrum is as Figure 1 shown. In Figure 1 , the peaks at 670 cm -1 and 712 cm -1 represent the peaks of nickel silicate. After the impregnated mixture was dried and calcined under the above conditions, transmission electron microscopy was performed, and the obtained TEM image is asFigure 2 As shown in Figure 2 It can be seen that the nickel silicate formed in this example is layered, and it presents disordered strips in the TEM image. Therefore, it can be proved that layered nickel silicate is formed during the impregnation process of this example. Figure 3 This is the transmission electron microscope image of the Ni / Beta catalyst of this example and the distribution result of the metal particle size. It can be seen that Ni is highly dispersed on the support, and its average particle size is 4.2 nm.

[0084] Example 3

[0085] This example provides a molecular sieve supported metal catalyst, and its preparation method includes the following steps:

[0086] Dissolve 3.96 g of nickel nitrate hexahydrate in 15 mL of deionized water, then add tetrapropylammonium hydroxide and stir evenly to obtain an impregnation solution with a pH value of 13.5; then add 10 g of Beta molecular sieve (the silica-alumina ratio is 50, the micropore volume is 0.18 cm 3 ·g -1 , and the mesopore volume is 0.23 cm 3 ·g -1 ) into the above impregnation solution and stir evenly, then transfer it to a sealed container and place it in an oven at 120 °C for static impregnation for 12 h; dry the impregnated mixture at 100 °C for 12 h, then calcine it in an air atmosphere at 400 °C for 4 h, and then reduce it in a pure hydrogen atmosphere at 550 °C for 2 h to obtain the Ni / Beta catalyst.

[0087] This Ni / Beta catalyst includes a Beta molecular sieve support and Ni supported on the Beta molecular sieve support. Based on the total mass of the Beta molecular sieve support being 100%, the content of Ni in this Ni / Beta catalyst in terms of atoms is 8%. The average particle size of Ni in this Ni / Beta catalyst is 8.8 nm, and the dispersion degree of Ni is 11.4%.

[0088] Example 4

[0089] This example provides a molecular sieve supported metal catalyst, and its preparation method includes the following steps:

[0090] Dissolve 1.98 g of nickel nitrate hexahydrate in 15 mL of deionized water, then add tetraethylammonium hydroxide and stir evenly to obtain an impregnation solution with a pH value of 14; then add 10 g of ZSM-5 molecular sieve (the silica-alumina ratio is 50, the micropore volume is 0.27 cm 3 ·g -1 , and the mesopore volume is 0.13 cm 3 ·g -1) It was added to the above impregnation solution and stirred evenly, then transferred to a sealed container and placed in an oven at 150 °C for static impregnation for 6 h; the impregnated mixture was dried at 100 °C for 14 h, then calcined in an air atmosphere at 400 °C for 4 h, and then reduced in a pure hydrogen atmosphere at 550 °C for 2 h to obtain the Ni / ZSM-5 catalyst.

[0091] The Ni / ZSM-5 catalyst includes a ZSM-5 molecular sieve support and Ni supported on the ZSM-5 molecular sieve support. Based on the total mass of the Beta molecular sieve support being 100%, the content of Ni in the Ni / ZSM-5 catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / ZSM-5 catalyst is 6.0 nm, and the dispersion of Ni is 16.7%.

[0092] Example 5

[0093] This example provides a molecular sieve-supported metal catalyst, and its preparation method includes the following steps:

[0094] 1.98 g of nickel nitrate hexahydrate was dissolved in 15 mL of deionized water, then tetraethylammonium hydroxide was added and stirred evenly to obtain an impregnation solution with a pH value of 14; then 10 g of MOR molecular sieve (the silica-alumina ratio is 25, the micropore volume is 0.24 cm 3 ·g -1 , and the mesopore volume is 0.16 cm 3 ·g -1 ) was added to the above impregnation solution and stirred evenly, then transferred to a sealed container and placed in an oven at 180 °C for static impregnation for 2 h; the impregnated mixture was dried at 100 °C for 14 h, then calcined in an air atmosphere at 400 °C for 4 h, and then reduced in a pure hydrogen atmosphere at 550 °C for 2 h to obtain the Ni / MOR catalyst.

[0095] The Ni / MOR catalyst includes a MOR molecular sieve support and Ni supported on the MOR molecular sieve support. Based on the total mass of the MOR molecular sieve support being 100%, the content of Ni in the Ni / MOR catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / MOR catalyst is 7.6 nm, and the dispersion of Ni is 13.2%.

[0096] Comparative Example 1

[0097] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from that of Example 2 is that tetraethylammonium hydroxide was not added, and the rest are the same as in Example 2, to obtain the Ni / Beta catalyst.

[0098] The Ni / Beta catalyst includes a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% by atom. The average particle size of Ni in the Ni / Beta catalyst is 11.5 nm, and the dispersion of Ni is 8.7%.

[0099] Comparative Example 2

[0100] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from Example 2 is that tetraethylammonium hydroxide is replaced with sodium hydroxide, the pH value of the impregnation solution remains unchanged, and the rest are the same as in Example 2, to obtain a Ni / Beta catalyst.

[0101] The Ni / Beta catalyst includes a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% by atom. The average particle size of Ni in the Ni / Beta catalyst is 16.4 nm, and the dispersion of Ni is 6.1%.

[0102] Comparative Example 3

[0103] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from Example 2 is that a small amount of tetraethylammonium hydroxide is added to make the pH value of the impregnation solution 9, and the rest are the same as in Example 2, to obtain a Ni / Beta catalyst.

[0104] The Ni / Beta catalyst includes a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% by atom. The average particle size of Ni in the Ni / Beta catalyst is 8.3 nm, and the dispersion of Ni is 12.0%.

[0105] Comparative Example 4

[0106] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from Example 2 is that an excessive amount of tetraethylammonium hydroxide is added to make the pH value of the impregnation solution 14.5, and the rest are the same as in Example 2, to obtain a Ni / Beta catalyst.

[0107] The Ni / Beta catalyst comprises a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / Beta catalyst is 7.1 nm, and the dispersion of Ni is 14.1%.

[0108] Comparative Example 5

[0109] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from that of Example 2 is that: in the impregnation process, the sealed container was placed in an oven at 40°C and left to stand for impregnation for 12 h, and the rest was the same as in Example 2, obtaining the Ni / Beta catalyst.

[0110] The Ni / Beta catalyst comprises a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / Beta catalyst is 12.4 nm, and the dispersion of Ni is 8.1%.

[0111] Comparative Example 6

[0112] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from that of Example 2 is that: in the impregnation process, the sealed container was placed in an oven at 240°C and left to stand for impregnation for 12 h, and the rest was the same as in Example 2, obtaining the Ni / Beta catalyst.

[0113] The Ni / Beta catalyst comprises a Beta zeolite support and Ni supported on the Beta zeolite support. Based on the total mass of the Beta zeolite support being 100%, the content of Ni in the Ni / Beta catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / Beta catalyst is 10.7 nm, and the dispersion of Ni is 9.3%.

[0114] Comparative Example 7

[0115] This comparative example provides a molecular sieve-supported metal catalyst. As a comparative example of Example 2, the difference in its preparation method from that of Example 2 is that: the Beta zeolite was replaced with SAPO-11 molecular sieve (silicon-aluminum ratio is 0.6, micropore volume is 0.23 cm 3 ·g -1 , mesopore volume is 0.11 cm 3 ·g -1 ), the dosage remains unchanged, and the rest is the same as in Example 2, obtaining the Ni / Beta catalyst.

[0116] The Ni / SAPO-11 catalyst includes a SAPO-11 molecular sieve support and Ni loaded on the SAPO-11 molecular sieve support. Based on the total mass of the SAPO-11 molecular sieve support being 100%, the content of Ni in the Ni / SAPO-11 catalyst is 4% in terms of atoms. The average particle size of Ni in the Ni / SAPO-11 catalyst is 13.4 nm, and the dispersion of Ni is 7.5%.

[0117] Catalyst performance evaluation

[0118] The catalysts prepared in the above examples and comparative examples were respectively evaluated for the catalytic performance of n-hexane hydroisomerization and the catalytic performance of hydrodeoxygenation of biodiesel.

[0119] The reaction conditions for the evaluation of the catalytic performance of n-hexane hydroisomerization include: using a fixed-bed reactor, the reaction temperature is 280 °C, the reaction pressure is 2.0 MPa, the volume space velocity of n-hexane is 1 h -1 , and the hydrogen-oil ratio (i.e., the molar ratio of hydrogen to n-hexane) is 4.0. The n-hexane conversion rate, isomer hexane selectivity, and isomer hexane yield are shown in Table 1. The conversion rate, selectivity, and yield were obtained by gas chromatography detection and calculation of the products.

[0120] n-Hexane conversion rate (%) = (moles of n-hexane in raw materials - moles of n-hexane in products) ÷ moles of n-hexane in raw materials × 100%. The moles of n-hexane in raw materials are known. The moles of n-hexane in products were obtained by gas chromatography detection.

[0121] Isomer hexane selectivity (%) = moles of n-hexane consumed to produce isomer hexane ÷ moles of n-hexane converted × 100%. The moles of isomer hexane produced were obtained by gas chromatography detection, and the moles of n-hexane consumed to produce isomer hexane were calculated through chemical equations. The moles of n-hexane converted = moles of n-hexane in raw materials - moles of n-hexane in products.

[0122] Isomer hexane yield (%) = n-hexane conversion rate × isomer hexane selectivity × 100%.

[0123] Table 1 Results of catalytic performance of n-hexane hydroisomerization

[0124]

[0125]

[0126] As can be seen from Table 1, compared with each comparative example, the n-hexane conversion rate, isomer hexane selectivity, and isomer hexane yield of the examples of the present invention are significantly improved, and it has higher catalytic activity and selectivity for n-hexane hydroisomerization.

[0127] The reaction conditions for evaluating the catalytic performance of hydrodeoxygenation of bio - oil include: the bio - oil used is methyl laurate, the reaction temperature is 280 °C, the hydrogen pressure is 2 MPa, and the catalyst - to - oil ratio (i.e., the mass ratio of the catalyst to the bio - oil) is 0.1. When the reaction time is 1 h, the conversion rate of methyl laurate, the selectivity of alkanes, and the selectivity of iso - alkanes therein are shown in Table 2. The conversion rate and selectivity are obtained by gas chromatography detection and calculation of the products.

[0128] The conversion rate of methyl laurate (%) = (the number of moles of methyl laurate in the raw material - the number of moles of methyl laurate in the product)÷the number of moles of methyl laurate in the raw material×100%. The number of moles of methyl laurate in the raw material is known. The number of moles of methyl laurate in the product is obtained by gas chromatography detection.

[0129] The selectivity of alkanes (%) = the number of moles of methyl laurate consumed for generating all alkanes÷the number of moles of methyl laurate converted×100%. The number of moles of generated alkanes is obtained by gas chromatography detection, and the number of moles of methyl laurate consumed for generating alkanes is calculated through chemical equations. The number of moles of methyl laurate converted = the number of moles of methyl laurate in the raw material - the number of moles of methyl laurate in the product.

[0130] The selectivity of iso - alkanes (%) = the number of moles of methyl laurate consumed for generating all iso - alkanes÷the number of moles of methyl laurate converted×100%. The number of moles of generated iso - alkanes is obtained by gas chromatography detection, and the number of moles of methyl laurate consumed for generating iso - alkanes is calculated through chemical equations. The number of moles of methyl laurate converted = the number of moles of methyl laurate in the raw material - the number of moles of methyl laurate in the product.

[0131] Table 2 Results of catalytic performance of hydrodeoxygenation of bio - oil

[0132] catalyst Conversion rate of methyl laurate (%) Alkane selectivity (%) Isoparaffin selectivity (%) Example 1 85.4 62.3 14.2 Example 2 98.8 71.5 22.6 Example 3 97.1 69.2 20.7 Example 4 95.3 70.8 18.9 Example 5 94.9 68.6 18.8 Comparative Example 1 90.6 60.2 10.3 Comparative Example 2 82.5 57.7 11.0 Comparative Example 3 92.2 60.9 12.3 Comparative Example 4 92.8 63.0 13.8 Comparative Example 5 88.2 56.9 10.2 Comparative Example 6 90.7 60.1 11.8 Comparative Example 7 84.0 52.5 9.3

[0133] It can be seen from Table 2 that compared with each comparative example, the conversion rate of methyl laurate, the selectivity of alkanes, and the selectivity of iso - alkanes in the examples of the present invention are significantly improved, having higher catalytic activity and selectivity for hydrodeoxygenation of bio - oil. The catalyst of the examples of the present invention is suitable for the production of bio - aviation kerosene with a low freezing point, and the higher selectivity of iso - hydrocarbons can significantly improve the low - temperature flow performance of bio - aviation kerosene.

[0134] The above - mentioned specific embodiments further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above - mentioned are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a molecular sieve-supported metal catalyst, comprising the following steps: (1) using a mixed solution containing a metal precursor, a hydroxide-based organic amine template and water as an impregnation solution, and immersing the molecular sieve in the impregnation solution under heating conditions, and obtaining a mixture after the impregnation is completed; (2) The mixture is at least dried, calcined and reduced to obtain the molecular sieve-supported metal catalyst.

2. The preparation method according to claim 1, wherein In step (1), the metal precursor includes one or more of a soluble nickel salt and a soluble molybdenum salt; Preferably, the metal precursor includes one or more of nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, ammonium molybdate, sodium molybdate and molybdenum nitrate.

3. The preparation method according to claim 1, wherein In step (1), the hydroxide-based organic amine template comprises a compound having a structure shown in Formula I: In Formula I, R1, R2, R3 and R4 are each independently selected from one of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; Preferably, in Formula I, R1, R2, R3 and R4 are each independently selected from a C1-C18 straight or branched alkyl group; More preferably, the hydroxide-based organic amine template includes one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

4. The preparation method according to claim 1, wherein In step (1), the pH value of the impregnation solution is 10-14.

5. The preparation method according to claim 1, wherein In step (1), the molecular sieve has a silicon to aluminum ratio of 25 or more; Preferably, the molecular sieve includes one or more of Beta molecular sieve, ZSM-5 molecular sieve, ZSM-22 molecular sieve, S-1 molecular sieve and MOR molecular sieve.

6. The preparation method according to claim 1, wherein In step (1), the heating temperature for the immersion is 50-200° C., and the immersion time is 2-36 hours.

7. The preparation method according to claim 1, wherein In step (1), the ratio of the mass of the molecular sieve to the volume of the impregnation solution is (10-20) g: (15-30) mL.

8. The preparation method according to claim 1, wherein In step (2), the calcination temperature is 350-550°C and the calcination time is 2-6h; Preferably, in step (2), the reduction temperature is 400-600° C. and the time is 2-6 hours.

9. A molecular sieve-supported metal catalyst, which is prepared by the method for preparing a molecular sieve-supported metal catalyst according to any one of claims 1 to 8; the molecular sieve-supported metal catalyst comprises: A molecular sieve carrier, and a metal component supported on the molecular sieve carrier; Preferably, the metal component comprises nickel and / or molybdenum; Preferably, based on the total mass of the molecular sieve carrier being 100%, the content of the metal component in the molecular sieve-supported metal catalyst in terms of metal atoms is 2% to 10%; Preferably, the average particle size of the metal component in the molecular sieve-supported metal catalyst is 4-15 nm; Preferably, the dispersion degree of the metal component in the molecular sieve-supported metal catalyst is 6%-25%.

10. Use of the molecular sieve-supported metal catalyst according to claim 9 as a catalyst in alkane hydroisomerization reaction and / or bio-oil hydrodeoxygenation reaction; Preferably, the alkane hydroisomerization reaction comprises n-hexane hydroisomerization reaction.

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