Nickel metal hydroisomerization catalyst as well as preparation method and application thereof

Abstract

The invention provides a nickel metal hydroisomerization catalyst as well as a preparation method and application thereof. The catalyst comprises nickel, an alumina carrier and a molecular sieve, the nickel is loaded on the alumina carrier, and the content of the nickel in the catalyst is 1-10wt%; the molecular sieve is an SAPO molecular sieve. According to the invention, alumina is used as a carrier, non-noble metal nickel is loaded through a wet immersion method and is mixed with the molecular sieve to prepare the alkane isomerization catalyst, so that active metal with smaller particle size and higher dispersity can be provided, metal agglomeration at high temperature is avoided, and the utilization rate of metal is increased; the catalyst with excellent catalytic activity can be obtained only by loading low-content nickel metal, the catalyst has higher catalytic activity and selectivity, the obtained product contains more isomers, and the low-temperature fluidity of the product can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of hydroisomerization catalyst preparation technology, and in particular to a nickel metal hydroisomerization catalyst, its preparation method, and its uses. Background Technology

[0002] With the increasing energy demand in modern society, reducing the high energy consumption and emissions associated with the use of fossil fuels and achieving the efficient and clean utilization of fossil energy has become the core of a sustainable energy utilization strategy. Coal is an abundant fossil fuel resource, with huge reserves in some regions. Fischer-Tropsch synthesis is an indirect liquefaction process that converts coal into liquid fuel, enabling more efficient and widespread utilization of coal energy resources. Fischer-Tropsch synthesis produces Fischer-Tropsch wax, which can be converted into lubricating oil through a hydroisomerization reaction. This conversion changes the structure of Fischer-Tropsch wax from linear to branched, lowering the pour point and improving the low-temperature fluidity of the lubricating oil.

[0003] The core of hydroisomerization technology lies in designing highly efficient bifunctional catalysts. These catalysts mainly consist of a metal active component and an acidic support working synergistically. The metal active center, typically a noble metal such as platinum or palladium, promotes hydrogenation and dehydrogenation reactions, while the acidic center, usually a one-dimensional ten-membered ring molecular sieve, is primarily responsible for the rearrangement of carbon-carbon bonds in olefin intermediates. This bifunctional synergy enables the catalyst to effectively convert reactants into isomerized products with specific structures and properties. However, the high price of noble metals significantly increases the production cost of the hydroisomerization process. Furthermore, noble metal catalysts are highly sensitive to sulfur, nitrogen, and arsenic compounds in the feedstock, and are easily poisoned and deactivated. Therefore, developing non-noble metal-based, low-cost hydroisomerization catalysts is highly attractive. However, to achieve the catalytic effect of noble metals, non-noble metals can only achieve this by increasing their loading. At high loadings, non-noble metals inevitably aggregate, especially during high-temperature processing, where they accumulate in large quantities and form large particle clusters. Nickel, as a widely used and relatively low-cost catalyst, plays a key role in many fields such as hydrogenation and methanation. However, as a hydrogenation isomer catalyst, it still has problems such as insufficient catalytic activity, poor dispersibility, poor selectivity, easy initiation of side reactions, and weak resistance to poisoning. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a nickel metal hydrogenation isomer catalyst, its preparation method and uses, to solve the problems of insufficient catalytic activity, poor dispersibility, poor selectivity and easy initiation of side reactions in the prior art.

[0005] To achieve the above and other related objectives, the present invention provides a nickel metal hydroisomerization catalyst, its preparation method, and its uses.

[0006] The first aspect of the present invention provides a method for C10 ~C 14 A nickel metal catalyst for the hydroisomerization of straight-chain alkanes, the catalyst comprising: nickel, an alumina support, and a molecular sieve; wherein the nickel is supported on the alumina support, and the nickel content in the catalyst is 1–10 wt%; the molecular sieve is a SAPO molecular sieve.

[0007] More preferably, the nickel content in the catalyst is 3-7 wt%; including but not limited to 3 wt%, 4 wt%, 5 wt%, 6 wt%, and 7 wt%.

[0008] Preferably, the catalyst contains 5 wt% nickel.

[0009] Preferably, the alumina is γ-Al2O3.

[0010] Preferably, the specific surface area of ​​the alumina is 50–300 m². 2 / g; for example, it can be 50m 2 / g, 100m 2 / g, 150m 2 / g、200m 2 / g、250m 2 / g、300m 2 The value can be any value within the range of / g, and can be adjusted according to the actual situation.

[0011] More preferably, the specific surface area of ​​the alumina is 50–200 m². 2 / g.

[0012] Preferably, the nickel in the catalyst has a particle size of 5 to 50 nm; for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 35 nm, 40 nm, 45 nm, or 50 nm.

[0013] More preferably, the modal particle size of nickel in the catalyst is 10-25 nm; for example, it can be 10 nm, 15 nm, 20 nm, or 25 nm.

[0014] The mode particle size mentioned in this invention is the particle size value that appears most frequently among all the measured particles.

[0015] Preferably, the molecular sieve includes any one or more of SAPO-11, SAPO-31, and SAPO-41.

[0016] More preferably, the molecular sieve is SAPO-11.

[0017] Preferably, the mass ratio of nickel to alumina in the catalyst is (1-20):100; the mass ratio of nickel to alumina in the catalyst can be any value in (1-20):100, and can be adjusted according to actual conditions, for example, it can be 1:100, 5:100, 10:100, 15:100, or 20:100.

[0018] Preferably, the mass ratio of alumina to molecular sieve in the catalyst is (0.2-5):1; for example, it can be 0.2:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, or 5:1.

[0019] More preferably, the mass ratio of alumina to molecular sieve in the catalyst is (0.2-2):1.

[0020] More preferably, the mass ratio of alumina to molecular sieve in the catalyst is (0.3-1):1.

[0021] Most preferably, the mass ratio of alumina to molecular sieve in the catalyst is (0.5-1):1.

[0022] A second aspect of the present invention provides a combination of γ-Al₂O₃ and SAPO molecular sieves as C 10 ~C 14 A nickel metal catalyst support for the hydroisomerization of straight-chain alkanes, used to improve C1... 10 ~C 14 Applications of isoparaffin yield.

[0023] Preferably, the use is a combination of γ-Al₂O₃ and SAPO molecular sieve as C 12 A nickel metal catalyst support for the hydroisomerization of straight-chain alkanes, used to improve C1... 12 Isoparaffin yield.

[0024] A third aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising: dissolving a soluble salt of nickel in water to obtain an aqueous metal solution; mixing and stirring alumina with the aqueous metal solution to form a gel texture, and allowing it to stand for 10-15 hours to obtain a precursor; drying, calcining, and cooling the precursor to obtain nickel-supported alumina; and mixing and grinding the nickel-supported alumina with a molecular sieve to form a powder to obtain the catalyst.

[0025] Preferably, the soluble salt of nickel is selected from one or more of nickel nitrate, nickel chloride, and nickel sulfate.

[0026] More preferably, the soluble salt of nickel is nickel nitrate.

[0027] Preferably, the concentration of nickel in the aqueous metal solution is 250–350 mg / mL; for example, it can be 250 mg / mL, 280 mg / mL, 300 mg / mL, 320 mg / mL, or 350 mg / mL.

[0028] More preferably, the concentration of nickel in the aqueous metal solution is 280–320 mg / mL.

[0029] Most preferably, the concentration of nickel in the aqueous metal solution is 300 mg / mL.

[0030] Preferably, the drying temperature is 60 to 100°C; for example, it can be 60°C, 70°C, 80°C, 90°C, or 100°C.

[0031] More preferably, the drying temperature is 70–90°C.

[0032] Preferably, the drying time is 2 to 6 hours; for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0033] More preferably, the drying time is 3 to 5 hours.

[0034] Preferably, the calcination temperature is 400–600°C; for example, it can be 400°C, 450°C, 500°C, 550°C, or 600°C.

[0035] More preferably, the calcination temperature is 450–500°C.

[0036] Preferably, the calcination time is 2 to 6 hours; for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0037] More preferably, the calcination time is 3 to 5 hours.

[0038] The fourth aspect of the present invention provides a catalyst for catalyzing C 10 ~C 14 Applications in the hydrogenation isomerization of straight-chain alkanes.

[0039] Preferably, the C 10 ~C 14 The straight-chain alkane is selected from any one or more of n-decane, n-undecane, n-dodecane, n-tridecane, and n-tetradecane.

[0040] More preferably, the straight-chain alkane is n-dodecane.

[0041] The fifth aspect of the present invention provides a method for catalyzing C using the above-described catalyst. 10 ~C 14 A method for the hydroisomerization of straight-chain alkanes, characterized in that the method comprises the following steps:

[0042] S1. Pre-reduction of the catalyst in a hydrogen atmosphere;

[0043] S2. The reduced catalyst is loaded into the reactor, and C is added. 10 ~C 14 Straight-chain alkanes and hydrogen undergo a catalytic reaction.

[0044] Preferably, in step S1, based on 1.5g of catalyst, the flow rate of hydrogen is 50-100ml / min; for example, it can be 50ml / min, 60ml / min, 70ml / min, 80ml / min, 90ml / min, or 100ml / min.

[0045] Preferably, in step S1, the reduction temperature is 350 to 650°C; for example, it can be 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or 650°C.

[0046] More preferably, in step S1, the reduction temperature is 350–450°C.

[0047] Preferably, in step S1, the reduction time is 4 to 24 hours; for example, it can be 4 hours, 8 hours, 10 hours, 15 hours, 20 hours, 22 hours, or 24 hours.

[0048] More preferably, in step S1, the reduction time is 4 to 6 hours.

[0049] Preferably, in step S2, the temperature of the catalytic reaction is 250–350°C.

[0050] More preferably, in step S2, the temperature of the catalytic reaction is 280–350°C.

[0051] Preferably, the pressure of the catalytic reaction is 1 to 3 MPa.

[0052] More preferably, the pressure of the catalytic reaction is 1.5 to 2.5 MPa.

[0053] Preferably, the space velocity of the straight-chain alkanes in the catalytic reaction is 1–3 h⁻¹. -1 For example, it could be 1 hour. -1 1.5h -1 2h -1 2.5h -1 3h -1 .

[0054] The above space velocity represents 1 to 3 volumes of straight-chain alkanes per hour passing through 1 volume of catalyst.

[0055] Preferably, in step S2, the molar ratio of hydrogen to straight-chain alkane is (10-20):1; for example, it can be 10:1, 12:1, 15:1, 18:1, or 20:1.

[0056] More preferably, in step S2, the molar ratio of hydrogen to straight-chain alkane is (13-18):1.

[0057] Preferably, the catalyst in the catalytic reaction has a mesh size of 30 to 50 mesh; for example, it can be 30 mesh, 35 mesh, 40 mesh, 45 mesh, or 50 mesh.

[0058] Preferably, in the catalytic reaction, C 10 ~C 14 The yield of isoparaffins is ≥65%.

[0059] More preferably, in the catalytic reaction, C 10 ~C 14 The yield of isoalkanes is 65%–80%.

[0060] As described above, the nickel metal hydroisomerization catalyst, its preparation method, and its uses of the present invention have the following beneficial effects:

[0061] This invention utilizes alumina as a support to prepare an alkane isomerization catalyst by loading non-precious metal nickel via wet impregnation and mixing it with molecular sieves. This provides active metals with smaller particle sizes and higher dispersion to avoid metal agglomeration at high temperatures. The oxide support with abundant specific surface area disperses the active metal, improving metal utilization. The strong interaction between metallic nickel and the alumina support results in better dispersibility and higher activity of the metal on the catalyst. Compared with conventional metal-acid catalysts, it exhibits higher activity and selectivity, and the obtained product contains more isomers, which can significantly improve the low-temperature fluidity of the product. It can catalyze the conversion of n-chain alkanes to branched alkanes via hydroisomerization reactions.

[0062] The catalyst preparation method of the present invention is simple and low in cost. It only requires a low nickel metal content (1-10 wt%) to enable the catalyst to have excellent catalytic activity and has high industrial application value. Attached Figure Description

[0063] Figure 1 The diagram shows the transmission electron microscopy morphology of the catalyst in Example 1 of this invention and the particle size distribution of nickel in the catalyst.

[0064] Figure 2 The diagram shows the relationship between the conversion rate of n-dodecane and temperature during the hydrogenation isomerization reaction of n-dodecane using the catalysts in Example 1 and Comparative Examples 1-2 of this invention.

[0065] Figure 3The figure shows the dodecane conversion rate and C1 ratio in the n-dodecane hydroisomerization reaction using the catalysts in Example 1 and Comparative Examples 1-2 of this invention. 12 A schematic diagram of the isomer yield relationship. Detailed Implementation

[0066] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0067] It should be noted that the process equipment or apparatus not specifically specified in the following embodiments are all conventional equipment or apparatus in the art. Furthermore, it should be understood that one or more method steps mentioned in this invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0068] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention; in the specification and claims of the present invention, unless otherwise expressly stated in the text, the singular forms "a", "an" and "this" include the plural forms.

[0069] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0070] To address the high cost of precious metal catalysts in existing technologies, this application proposes a novel nickel-based catalyst. Using non-precious metal nickel as the active ingredient, it is loaded onto an alumina support to improve dispersibility and prevent metal particle agglomeration. Furthermore, it is mixed with SAPO molecular sieves to regulate acidic sites, achieving excellent catalytic performance with a relatively low nickel loading. The catalyst preparation method in this application includes the following steps:

[0071] S1. Dissolve nickel nitrate in water to prepare an aqueous solution of nickel nitrate with a nickel concentration of 280-320 mg / mL.

[0072] S2. Add nickel nitrate aqueous solution to alumina, stir until gel texture is formed, and let stand at 20-30℃ for 10-14 hours to obtain the precursor.

[0073] S3. After drying the precursor, calcine it in air and cool it to 20-30°C to obtain an alumina carrier containing active metal dispersion.

[0074] S4. The alumina support containing active metal dispersion is mixed with SAPO-11 molecular sieve and ground into powder to obtain the alkane isomerization catalyst.

[0075] In step S1 above, the concentration of nickel in the nickel nitrate aqueous solution is controlled at 280–320 mg / mL so that the nickel nitrate aqueous solution and alumina can be stirred into a gel in step S2 above. After stirring into a gel, the viscosity of the system increases significantly, which prevents uneven migration of metal ions during the drying process. At the same time, it maximizes and closely contacts the solution with the inner and outer surfaces of the alumina support on a microscopic level, thereby ensuring that the metallic nickel is highly dispersed and highly uniformly distributed on the alumina support.

[0076] In some specific embodiments of this application, the alumina in step S2 above is γ-Al2O3 with a specific surface area of ​​50-200 m². 2 / g.

[0077] In some specific embodiments of this application, the drying in step S3 is carried out in an oven at a temperature of 75–85°C for 3.5–4.5 hours.

[0078] In some specific embodiments of this application, the calcination in step S3 is carried out in a muffle furnace at a temperature of 450–500°C for 3.5–4.5 hours.

[0079] In some specific embodiments of this application, the process further includes heating to the calcination temperature before calcination, wherein the heating rate is 0.5 to 1.5 °C / min.

[0080] In some specific embodiments of this application, the mass ratio of nickel to alumina in the alumina carrier containing active nickel metal dispersion obtained in step S3 above is (4-20):100.

[0081] In some specific embodiments of this application, the mass ratio of alumina in step S2 to SAPO-11 molecular sieve in step S4 is (0.3~2):1.

[0082] In some specific embodiments of this application, the nickel content in the catalyst is 3-7 wt%.

[0083] The nickel nitrate (Ni(NO3)2) aqueous solution used in Examples 1-6 and Comparative Examples 1-2 below was a freshly prepared solution, and the concentration of Ni in the nickel nitrate solution was 300 mg / ml.

[0084] Example 1

[0085] In Example 1, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0086] S1. Add 0.5 mL of nickel nitrate aqueous solution to 1.5 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0087] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0088] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 1.5g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 1:1, and the mass percentage of nickel in the catalyst is 5wt%. It is named Ni / Al2O3-S11.

[0089] Example 2

[0090] In Example 2, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0091] S1. Add 0.67 mL of nickel nitrate aqueous solution to 1 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0092] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0093] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 3g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 1:3, and the mass percentage of nickel in the catalyst is 5wt%. It is named 0.3Ni / Al2O3-S11.

[0094] Example 3

[0095] In Example 3, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0096] S1. Add 0.5 mL of nickel nitrate aqueous solution to 1 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0097] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0098] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 2g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 1:2, and the mass percentage of nickel in the catalyst is 5wt%. It is named 0.5Ni / Al2O3-S11.

[0099] Example 4

[0100] In Example 4, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0101] S1. Add 0.5 mL of nickel nitrate aqueous solution to 2 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0102] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0103] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 1g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 2:1, and the mass percentage of nickel in the catalyst is 5wt%. It is named 2Ni / Al2O3-S11.

[0104] Example 5

[0105] In Example 5, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0106] S1. Add 0.3 mL of nickel nitrate aqueous solution to 1.5 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0107] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0108] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 1.5g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 1:1, and the mass percentage of nickel in the catalyst is 3wt%. It is named 3%Ni / Al2O3-S11.

[0109] Example 6

[0110] In Example 6, a catalyst was prepared by using γ-Al₂O₃ as a support, loading nickel metal, and mixing it with SAPO molecular sieves. The specific preparation method is as follows:

[0111] S1. Add 0.7 mL of nickel nitrate aqueous solution to 1.5 g γ-Al2O3, stir until gel texture is formed, and let stand at room temperature for 12 h to obtain the precursor.

[0112] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain an alumina support containing active nickel metal dispersion.

[0113] S3. The alumina support containing active nickel metal dispersion prepared in step S2 is mixed with 1.5g SAPO-11 molecular sieve and ground into powder using an agate mortar to obtain an alkane isomerization catalyst. The mass ratio of γ-Al2O3 to SAPO-11 molecular sieve in the catalyst is 1:1, and the mass percentage of nickel in the catalyst is 7wt%. It is named 7%Ni / Al2O3-S11.

[0114] Comparative Example 1

[0115] Comparative Example 1, without the addition of γ-Al₂O₃ support, prepared a catalyst by dispersing nickel metal in SAPO molecular sieves. The specific preparation method is as follows:

[0116] S1. Add 0.5 mL of nickel nitrate aqueous solution to 3 g of SAPO-11 molecular sieve, stir well, and let stand at room temperature for 12 h to obtain the precursor.

[0117] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain SAPO-11 molecular sieve containing active nickel metal dispersion.

[0118] S3. Grind the SAPO-11 molecular sieve containing active nickel metal dispersion prepared in step S2 into powder to obtain a catalyst, which is named Ni / S11.

[0119] Comparative Example 2

[0120] Comparative Example 2, without the addition of SAPO molecular sieves, prepared a catalyst by dispersing nickel metal in a γ-Al₂O₃ support. The specific preparation method is as follows:

[0121] S1. Add 0.5 mL of nickel nitrate aqueous solution to 3 g of γ-Al2O3 support, stir well, and let stand at room temperature for 12 h to obtain the precursor.

[0122] S2. After drying the precursor prepared in step S1 in an oven at 80°C for 4 hours, place it in a muffle furnace and heat it to 480°C in air at a heating rate of 1°C / min and calcine it for 4 hours. Then cool it to room temperature to obtain a γ-Al2O3 support containing active nickel metal dispersion.

[0123] S3. Grind the γ-Al2O3 support containing active nickel metal dispersion prepared in step S2 into powder to obtain a catalyst, which is named Ni / Al2O3.

[0124] Test section

[0125] The nickel dispersion and catalytic performance as hydroisomerization catalysts of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 were tested below.

[0126] 1) The particle size of nickel in the prepared powdered catalyst was measured using transmission electron microscopy (TEM). The test results are shown in Table 1. The particle size values ​​in Table 1 are the mode size. Figure 1 This is a TEM schematic diagram of the catalyst in Example 1. The bright areas in the diagram represent nickel, and the gray areas represent molecular sieves and alumina.

[0127] 2) Using n-dodecane and hydrogen as reactants, the catalytic performance of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 was tested. Specifically: the powdered catalyst was tableted into cylindrical shapes using a tablet press, then crushed and sieved through a 40-mesh screen to obtain catalyst particles for subsequent catalytic reactions. 1.5g of catalyst was packed into a fixed-bed reactor, and the catalyst was pre-reduced under a pure hydrogen atmosphere by heating to 400℃ at a rate of 5℃ / min for 4 hours, with a hydrogen flow rate of 80ml / min. Then, the n-dodecane hydroisomerization reaction was carried out in the fixed-bed reactor, with a reaction temperature of 280-350℃, a reaction pressure of 2MPa, and a n-dodecane space velocity of 1.5h. -1 The molar ratio of hydrogen to n-dodecane was 15; the results of the hydroisomerization of n-dodecane by the catalysts in each example and comparative example are shown in Table 1; among them, the catalysts prepared in Example 1 and Comparative Examples 1-2 were used to carry out catalytic reactions, and the relationship between reaction temperature and conversion rate during the reaction process is shown in Table 1. Figure 2 As shown, the relationship between reaction conversion rate and isomer yield is as follows: Figure 3 As shown. The formulas for calculating conversion rate and yield are as follows:

[0128]

[0129] Table 1

[0130] Experimental Example Sample Name Nickel metal particle size / nm Highest yield of isoalkanes / % Example 1 <![CDATA[Ni / Al2O3-S11]]> 14.4 76.1 Example 2 <![CDATA[0.3Ni / Al2O3-S11]]> 26.6 69.3 Example 3 <![CDATA[0.5Ni / Al2O3-S11]]> 20.1 75.0 Example 4 <![CDATA[2Ni / Al2O3-S11]]> 12 65.5 Example 5 <![CDATA[3%Ni / Al2O3-S11]]> - 67.3 Example 6 <![CDATA[7%Ni / Al2O3-S11]]> - 67.2 Comparative Example 1 Ni / S11 48.2 63.6 Comparative Example 2 <![CDATA[Ni / Al2O3]]> 9.6 27.2

[0131] Depend on Figure 2 It can be seen that when catalytic reactions are carried out using the catalysts prepared in Example 1 and Comparative Examples 1-2, the conversion rate of n-dodecane gradually increases with increasing reaction temperature; the conversion rate of the reaction using the catalyst in Example 1 is consistently higher than that of the reaction using the catalysts in Comparative Examples 1-2 within the temperature range of 280-350°C. Figure 3It can be seen that when using the catalyst in Comparative Example 2, the highest yield of the isomer was only 27.2%. When using the catalysts in Example 1 and Comparative Example 1, when the conversion of n-dodecane was below 90%, the yield of the isomer increased with increasing conversion. However, when the conversion exceeded 90%, the yield of the isomer decreased. This is because although the conversion increased with increasing reaction temperature, the isoalkanes generated at high temperatures are easily decomposed into short-chain hydrocarbons, thus leading to a decrease in C... 12 The yield of isoparaffins decreased.

[0132] As shown in Table 1, the alkane isomerization catalyst prepared by supporting nickel on alumina has a smaller metal particle size, resulting in higher yields when applied to the alkane isomerization reaction. Compared with the catalysts prepared in Examples 1-6 and Comparative Examples 1-2, the catalysts prepared by supporting non-noble metal nickel on conventional acidic molecular sieves tend to agglomerate under high metal loading conditions, leading to increased metal particle size, reduced metal dispersion, and decreased yield in the alkane isomerization reaction. Furthermore, compared with the catalyst prepared in Comparative Example 1, the introduction of Ni / Al2O3 into SAPO-11 significantly reduced the total number of acidic sites in the catalyst and increased the medium-strength... The increased number of acidic sites enhances the catalytic activity of Ni / Al2O3-S11. Comparing the catalysts prepared in Examples 1-6 with those in Comparative Example 2, it is evident that while using Al2O3 alone to support Ni metal significantly improves Ni dispersion, its catalytic activity is low, with the highest isoalkane yield being only 27.2%.

[0133] In summary, the alkane isomerization catalyst prepared using alumina as a non-precious metal support in this invention provides an active metal with smaller particle size and higher dispersion, thus avoiding metal agglomeration during high-temperature preparation. Furthermore, the introduction of alumina modulates the catalyst's acidity and the number of acidic sites, which is crucial for carbocation formation, skeletal isomerization, and cracking. Compared to conventional metal-acid bifunctional catalysts, it exhibits higher activity and selectivity, and the resulting product contains more isomers, significantly improving its low-temperature fluidity. It can catalyze the conversion of n-chain alkanes to branched alkanes via hydroisomerization reactions. Therefore, this invention has high industrial application value due to its effective reduction in the price of precious metal hydroisomerization catalysts.

[0134] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for C 10 ~C 14 A nickel metal catalyst for the hydroisomerization of straight-chain alkanes, characterized in that, The catalyst comprises: nickel, an alumina support, and a molecular sieve; the nickel is supported on the alumina support, and the nickel content in the catalyst is 1-10 wt%. The molecular sieve is a SAPO molecular sieve.

2. The catalyst according to claim 1, characterized in that, The alumina is γ-Al₂O₃; And / or, the specific surface area of ​​the alumina is 50–300 m². 2 / g; And / or, the nickel in the catalyst has a particle size of 5–50 nm; And / or, the molecular sieve includes any one or more of SAPO-11, SAPO-31, and SAPO-41.

3. The catalyst according to claim 1, characterized in that, The mass ratio of nickel to aluminum oxide in the catalyst is (1-20):100; And / or, the mass ratio of alumina to molecular sieve in the catalyst is (0.2-5):

1.

4. The combination of γ-Al₂O₃ and SAPO molecular sieves as C 10 ~C 14 A nickel metal catalyst support for the hydroisomerization of straight-chain alkanes, used to improve C1... 10 ~C 14 Applications of isoparaffin yield.

5. A method for preparing the catalyst according to any one of claims 1 to 3, characterized in that, include: A soluble salt of nickel is dissolved in water to obtain an aqueous metal solution; aluminum oxide is mixed with the aqueous metal solution and stirred to form a gel texture, which is then allowed to stand for 10–15 hours to obtain a precursor; the precursor is dried, calcined, and cooled to obtain nickel-supported aluminum oxide. The catalyst was obtained by mixing and grinding nickel-supported alumina with molecular sieves into powder.

6. The preparation method according to claim 5, characterized in that, The soluble salt of nickel is selected from any one or more of nickel nitrate, nickel chloride, and nickel sulfate; And / or, the concentration of nickel in the aqueous metal solution is 250–350 mg / mL.

7. The preparation method according to claim 5, characterized in that, The drying temperature is 60–100°C; And / or, the drying time is 2 to 6 hours; And / or, the calcination temperature is 400–600°C; And / or, the calcination time is 2 to 6 hours.

8. A catalyst according to any one of claims 1 to 3 in catalytic C 10 ~C 14 Applications in the hydrogenation isomerization of straight-chain alkanes.

9. A method for catalyzing C using the catalyst according to any one of claims 1 to 3. 10 ~C 14 The method for hydroisomerization of straight-chain alkanes is characterized by, The method includes the following steps: S1. Pre-reduction of the catalyst in a hydrogen atmosphere; S2. The reduced catalyst is loaded into the reactor, and C is added. 10 ~C 14 Straight-chain alkanes and hydrogen undergo a catalytic reaction.

10. The method according to claim 9, characterized in that, In step S1, based on 1.5g of catalyst, the flow rate of hydrogen is 50-100ml / min; And / or, in step S1, the reduction temperature is 350–650°C, and the reduction time is 4–24 h; And / or, in step S2, the space velocity of the straight-chain alkane is 1–3 h⁻¹. -1 . And / or, in step S2, the temperature of the catalytic reaction is 250–350°C, and the pressure of the catalytic reaction is 1–3 MPa; And / or, in step S2, the hydrogen gas reacts with C 10 ~C 14 The molar ratio of straight-chain alkanes is (10-20):

1.

11. The method according to claim 9 or 10, characterized in that, In the catalytic reaction, C 10 ~C 14 The yield of isoparaffins is ≥65%.

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