Carrier-supported sulfurized nickel-based spinel catalyst as well as preparation method and application thereof

Abstract

The invention discloses a carrier-supported sulfurized nickel-based spinel catalyst and a preparation method and application thereof.The catalyst comprises a porous carrier and a Ni-M-S spinel type or spinel-like type sulfide active phase loaded on the surface and / or in pores of the porous carrier, the active phase comprises sulfide with a controllable and adjustable structure, the chemical composition formula of the active phase is NixMyS4, wherein M is selected from at least one of Co, Fe, Mn and Cr, x is larger than or equal to 0.5 and smaller than or equal to 1.5, and y is larger than or equal to 1.5 and smaller than or equal to 2.5. The catalyst realizes effective regulation and control of an active site electronic structure by constructing a stable metal-sulfur-metal three-dimensional skeleton structure, and shows excellent catalytic activity and long-chain olefin selectivity in a decarbonylation-dehydration reaction of bio-based fatty acid or derivatives thereof. Meanwhile, a firm interface anchoring structure is formed between the catalyst and the porous carrier, and the intrinsic structural stability of the spinel phase is matched, so that the catalyst can keep long-term stable operation under a continuous reaction condition, and the regeneration frequency and the operation cost are remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a supported sulfide nickel-based spinel catalyst and its preparation method, as well as the application of the catalyst in the decarbonylation-dehydration reaction of bio-based fatty acids or their derivatives to prepare long-chain olefins. Background Technology

[0002] Long-chain olefins are key raw materials for the synthesis of surfactants, lubricating oil base oils, plasticizers, and specialty polymers, and are widely used in several strategic industries such as fine chemicals, materials manufacturing, and new energy, with consistently stable market demand. Currently, the industrial production of long-chain olefins mainly relies on fossil resource routes such as naphtha cracking, Fischer-Tropsch synthesis, and alkane dehydrogenation. However, these processes have significant drawbacks: dispersed carbon chain distribution in the products, low selectivity for target products, high energy consumption, and complete dependence on non-renewable petroleum resources. Driven by the "dual carbon" goals (carbon reduction and emission reduction), traditional fossil routes can no longer meet the demands of green and sustainable industrial development. Developing long-chain olefin production technologies based on renewable resources has become a core industry demand.

[0003] Renewable resources such as animal and vegetable oils and waste cooking oil are rich in C10-C20 fatty acids and their esters. Their molecular structures naturally possess long-chain alkane skeletons, which can be directionally converted into target long-chain olefins simply through a decarbonylation-dehydration reaction. This makes them ideal renewable carbon sources to replace fossil resources. Compared to traditional fossil routes, the decarbonylation-dehydration method for fatty acids or their derivatives has advantages such as shorter reaction steps, lower theoretical hydrogen consumption, and a direct carbon conversion pathway. However, the key bottleneck for its industrial application lies in the insufficient performance of the catalyst system.

[0004] The catalysts currently used for this reaction mainly include noble metal catalysts (such as Pd and Pt) and transition metal oxide catalysts. Although noble metal catalysts have high catalytic activity, they suffer from problems such as high cost, susceptibility to over-hydrogenation side reactions, and easy deactivation after long-term use, making it difficult to meet the cost control and stability requirements for large-scale industrial applications. Transition metal oxide catalysts, on the other hand, generally suffer from defects such as poor selectivity for target olefins, insufficient dispersion of the active phase, and easy agglomeration and deactivation at high temperatures. Furthermore, their stability decreases further when processing actual raw materials containing water, unsaturated bonds, or trace impurities (such as waste oils).

[0005] Furthermore, the active phase structure of existing catalysts is mostly simple particulate, lacking precise control over the morphology of the active phase. This results in insufficient exposure of active sites and weak metal-support interface interactions, further limiting the improvement of catalytic performance. Currently, there is no catalyst in the industry that can simultaneously solve the three core problems of "high cost, low selectivity, and poor stability," especially lacking sulfide-based nickel catalysts with specific hierarchical structures, controllable stoichiometry, and compatibility with complex renewable feedstock systems, as well as their efficient preparation processes.

[0006] Therefore, developing a catalyst that is low in cost, has high catalytic activity, excellent olefin selectivity, strong structural stability, and is suitable for the conversion of bio-based fatty acids or their derivatives is of great significance for promoting the green and sustainable development of the long-chain olefin industry. Summary of the Invention

[0007] To address the problems of existing technologies in the preparation of long-chain olefins, such as reliance on fossil resources and the high cost, low activity, poor selectivity, and insufficient stability of catalysts, this invention aims to provide a supported sulfide-based nickel-based spinel catalyst, its preparation method, and its application in the synthesis of long-chain olefins from bio-based fatty acids or their derivatives. This catalyst uses non-precious metals as the active component, resulting in low cost, while exhibiting excellent catalytic activity (conversion rate ≥95%), high long-chain olefin selectivity (≥85%), and long-term structural stability (continuous operation ≥1000h). This can reduce industrial operating costs and achieve the green conversion of renewable resources into high-value chemicals.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A supported nickel-based spinel catalyst with sulfide state comprises a porous support and a sulfide-state active phase supported on the surface and / or within the pores of the porous support; the sulfide-state active phase is a sulfide having a spinel-type or spinel-like crystal structure, and its chemical composition is expressed in the general formula Ni. x M y S4 indicates that M is selected from at least one of Co, Fe, Mn, and Cr, the value of x is in the range of 0.5≤x≤1.5, and the value of y is in the range of 1.5≤y≤2.5; the total mass fraction of metal element Ni and M in the catalyst is 5wt% to 40wt%.

[0009] Preferably, the porous carrier is a composite carrier composed of one or more of mesoporous carbon, activated carbon, coconut shell carbon, graphitized carbon, silicon dioxide, and alumina.

[0010] Preferably, the catalyst has a specific surface area of ​​150–800 m². 2 / g, pore volume 0.3~2.0cm 3 / g, the carrier has a mesopore size of 3-50nm.

[0011] Preferably, the sulfurized active phase exhibits at least one microstructure selected from nanosheets, nanorods, nanoflowers, or nanoporous crystals. Nanosheets (preferably 5–10 nm thick), nanorods (preferably 10–20 nm in diameter and 100–200 nm in length), and nanoflowers (preferably 50–100 nm in particle size) have a specific surface area 2–3 times higher than ordinary particles, exposing more active sites (more than 40%). Simultaneously, the unique morphological structure increases the product desorption rate by 50%, further suppressing secondary reactions.

[0012] A method for preparing a supported sulfide-based spinel catalyst includes the following steps: S1. Pretreatment: The porous support is heat-treated in an atmosphere of nitrogen or argon. The heat treatment temperature is 280-350°C and the heat treatment time is 2-3 hours. The heat treatment atmosphere is either nitrogen or argon. S2, Loading: A solution containing Ni source and M source is loaded onto a treated porous support by at least one of the following methods: impregnation, co-precipitation, solvothermal or hydrothermal method to form a Ni-M precursor complex. Specific operations for each load method: ① Impregnation method: The solid-liquid ratio of carrier to solution is 1:5 to 1:20 (g / mL), impregnate at room temperature for 8 to 24 hours, and dry at 80 to 120℃ for 4 to 8 hours; ② Coprecipitation method: Add ammonia or sodium carbonate solution dropwise to the solution to adjust the pH to 7.0-10.0, stir at 30-60℃ for 2-6 hours, filter and wash until the pH of the filtrate is 7, and dry at 80-100℃ for 6-12 hours; ③ Solventothermic method: Using ethanol, ethylene glycol or toluene as solvent, the solid-liquid ratio of the carrier to the solution is 1:10 to 1:30 (g / mL), and the reaction is carried out at 120 to 200℃ for 6 to 24 hours. After cooling, the mixture is filtered and dried at 80 to 100℃ for 4 to 8 hours. ④ Hydrothermal method: using deionized water as solvent, the solid-liquid ratio of the carrier to the solution is 1:8 to 1:25 (g / mL), reacting at 100 to 180℃ for 4 to 18 hours, filtering after cooling, and drying at 80 to 100℃ for 4 to 8 hours; S3. Calcination: Under a nitrogen atmosphere, the Ni-M precursor composite is calcined at a temperature of 250–550°C for 1–6 hours to decompose and oxidize the precursor, yielding supported Ni-MO spinel oxide. If the temperature is below 250°C, the precursor decomposes incompletely (decomposition rate < 80%); if the temperature is above 550°C, the oxide particles sinter (particle size increase > 50%), affecting the subsequent sulfidation effect. S4. Sulfidation: The supported Ni-MO spinel oxide is sulfidated in a sulfur-containing atmosphere at a temperature of 200–420°C for 2–10 hours to transform the oxide into sulfidated Ni-MS spinel or spinel-like structure. When the sulfidation temperature is below 200°C, the sulfidation reaction is insufficient (conversion rate < 70%); when the temperature is above 420°C, excessive sulfur deposition (sulfur content > 5 wt%) or destruction of the active phase structure occurs. S5. Activation: In a hydrogen atmosphere or a mixture of hydrogen and inert gas, the sulfided product is activated at a temperature of 220-420℃ for 0.5-1.5h to remove impurities and some weakly bound sulfur (weakly bound sulfur content ≤0.3wt%) adsorbed on the surface of the active phase, thereby activating the catalytic active sites and obtaining the desired catalyst.

[0013] Preferably, in step S2, the precursor is selected from nitrates, acetates, or organometallic complexes, and a structure-directing agent accounting for 1% to 10% of the total mass of the precursor is added during the loading process, forming a two-dimensional sheet-like or three-dimensional flower-like spinel structure; the structure-directing agent is at least one of hexadecyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG, molecular weight 2000-10000), or polyvinylpyrrolidone (PVP, molecular weight 5000-50000); wherein CTAB induces the formation of nanosheet morphology, PEG induces the formation of nanorod morphology, and PVP induces the formation of nanoflower morphology.

[0014] Preferably, in step S4, the sulfur-containing atmosphere is H2S, or a combination of H2S and sulfur vapor or H2S and CS2, wherein the volume fraction of H2S is 1% to 10%.

[0015] The application of a supported sulfide nickel-based spinel catalyst in the preparation of long-chain olefins includes the following steps: under the conditions of a reaction temperature of 200-350℃ and a hydrogen pressure of 0.1-3MPa, bio-based fatty acids or their derivatives are contacted with the catalyst to undergo a decarbonylation-dehydration reaction to generate long-chain olefins.

[0016] Preferably, the bio-based fatty acid or its derivative is a fatty acid with 10-20 carbon atoms, a fatty acid methyl ester with 10-20 carbon atoms, a fatty acid ethyl ester with 10-20 carbon atoms, or at least one of animal or vegetable oils or waste oils containing the above components. These raw materials are widely available, renewable, and have a high degree of matching between their carbon chain structure and the target long-chain olefin, resulting in excellent conversion efficiency.

[0017] Compared with the prior art, the technical solution of this invention has the following advantages: A. Excellent catalytic activity and selectivity: The sulfide active phase of the catalyst of this invention has a spinel-type or spinel-like structure, forming a stable metal-sulfur-metal three-dimensional framework, which greatly improves the selectivity for breaking CO bonds in fatty acid and its derivative molecules (more than 40%), while inhibiting non-selective breaking of C-C bonds and deep hydrogenation reactions. The proportion of alkane byproducts is reduced to less than 10%, and the selectivity of long-chain olefins can reach 85% to 95%, which is much higher than that of existing transition metal oxide catalysts (usually less than 60%).

[0018] B. Strong structural stability and long service life: The lattice distortion rate of the spinel or spinel-like structure is <2%, and the metal-sulfur bond binding energy is more than 1.3 times that of the metal-oxygen bond binding energy in traditional NiO, which can effectively inhibit the sintering and agglomeration of the active phase during the reaction process (particle size growth ≤10% after continuous operation for 1000h); at the same time, MSC interface anchoring bonds are formed between the active phase and the porous support (XPS characterization confirmed), the active phase loss rate is ≤3%, and the catalyst still maintains a conversion rate ≥90% and a selectivity ≥85% after continuous reaction for 1000-1200h, significantly reducing operating costs.

[0019] C. Low preparation cost and easy to scale up: The catalyst of this invention uses non-precious metals such as Ni, Co, and Fe as active components, and the raw material cost is only 1 / 50 to 1 / 100 of that of precious metal catalysts; the preparation method adopts mature processes such as impregnation method and co-precipitation method, the steps are simple and the operation is controllable (process repeatability ≥95%), the amount of structure directing agent used is small (1% to 10%) and easy to obtain, no special equipment is required, and it is suitable for large-scale industrial production.

[0020] D. In line with the concept of green and sustainable development: The catalyst of this invention is specifically designed for bio-based fatty acids and their derivatives, realizing the conversion of renewable resources into high-value long-chain olefins, replacing the traditional fossil resource route, and significantly reducing carbon emission intensity; at the same time, the reaction conditions are mild (temperature 200-350℃, pressure 0.1-3MPa), and the catalyst has strong stability and low regeneration frequency, further reducing the environmental burden and having significant economic value and social benefits. Detailed Implementation

[0021] This invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. All other embodiments derived by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Example 1

[0022] This embodiment discloses the preparation and application of a supported multimetallic sulfide nickel-based spinel catalyst. The preparation method includes the following steps: S1. Pretreatment: Take an alumina-silica composite carrier (mass ratio 1:1), heat treat it at 350℃ (heating rate 8℃ / min) for 3h under nitrogen atmosphere, cool it for later use, the residual moisture is 0.4wt%, and the hydroxyl density is 1.3mmol / g. S2. Loading: Weigh nickel acetate (Ni(CH3COO)2・4H2O), ferric nitrate (Fe(NO3)3・9H2O), and manganese nitrate (Mn(NO3)2・4H2O), and dissolve them in ethanol at a Ni to (Fe+Mn) molar ratio of 1:4 (Fe to Mn molar ratio of 1:1, x=0.5, y=2), with a total metal ion concentration of 0.3 mol / L; add 3% PVP (molecular weight 10000, structure directing agent) as a percentage of the total precursor mass, and ultrasonically disperse for 30 min; add the composite support to the above solution at a solid-liquid ratio of 1:15 (g / mL), and react at 120℃ for 6 h using a hydrothermal method, filter, and dry at 80℃ for 8 h to obtain the Ni-Fe-Mn precursor composite (total metal mass fraction 15 wt%). S3. Calcination: Calcination was carried out at 380℃ (heating rate 5℃ / min) for 4h under nitrogen atmosphere to obtain supported Ni-Fe-Mn-O spinel oxide; S4. Sulfidation: A mixed gas of H2S and H2 (H2S volume fraction 10%) was introduced, and sulfidation was carried out at 350℃ (heating rate 3℃ / min) for 5h to obtain a sulfidated Ni-Fe-Mn-S spinel structure. S5. Activation: Activate at 320℃ (heating rate 4℃ / min) for 0.5h in a mixed atmosphere of hydrogen and argon (volume ratio 1:1) to obtain the target catalyst (active phase is Ni). 0.5 FeMnS4 exhibits a nanoflower-like morphology with a particle size of 70 nm and a specific surface area of ​​320 m². 2 / g, pore volume 0.7cm 3 / g). Catalyst applications:

[0023] Take 5g of the above catalyst and place it in a fixed-bed reactor. Introduce n-dodecane-30wt% soybean oil (mainly containing C16-C18 fatty acid glycerides) as a reactant. The reaction temperature is 320℃, the hydrogen pressure is 3MPa, and the space velocity is 0.8h⁻¹. -1 The reaction was carried out for 800 hours under the action of the above catalyst. Product analysis results: soybean oil conversion rate 97.8%, total selectivity for long-chain olefins 90.7%. Example 2

[0024] This embodiment discloses the preparation and application of a supported sulfide-based nickel spinel catalyst. The preparation method includes the following steps: S1. Pretreatment: Take the mesoporous carbon support, place it in a muffle furnace, and heat treat it at 280℃ (heating rate 5℃ / min) for 2h under nitrogen atmosphere. Cool it to room temperature. The residual moisture is 0.3wt% and the hydroxyl density is 1.5mmol / g. S2. Loading: Weigh nickel nitrate (Ni(NO3)2・6H2O) and cobalt nitrate (Co(NO3)2・6H2O), dissolve them in deionized water at a Ni to Co molar ratio of 1:2.5 (x=1, y=2.5), with a total metal ion concentration of 0.5 mol / L; add 5% CTAB (structure directing agent) of the total precursor mass, and stir until completely dissolved; immerse the pretreated mesoporous carbon support in the above solution at a solid-liquid ratio of 1:10 (g / mL), impregnate at room temperature for 12 h, and then dry at 80 °C for 6 h to obtain the Ni-Co precursor composite (total metal mass fraction 20 wt%). S3. Calcination: The Ni-Co precursor composite was placed in a tube furnace and calcined at 250°C (heating rate 3°C / min) for 6 hours under a nitrogen atmosphere to obtain supported Ni-Co-O spinel oxide. S4. Sulfidation: A mixed gas of H2S and CS2 (H2S volume fraction 5%) is introduced into a tube furnace and sulfided at 420℃ (heating rate 2℃ / min) for 2h to obtain a sulfidated Ni-Co-S spinel structure. S5. Activation: Switch the atmosphere to pure hydrogen and activate at 420℃ (heating rate 3℃ / min) for 1 hour. After cooling, the target catalyst (active phase is NiCo) is obtained. 2.5 S4 exhibits a nanosheet morphology with a thickness of 8 nm; XPS analysis shows a Ni / S surface molar ratio of 1:3.3; and a specific surface area of ​​480 m². 2 / g, pore volume 1.1cm 3 / g). Catalyst applications:

[0025] Take 5g of the above catalyst and place it in a fixed-bed reactor. Introduce n-dodecane-30wt% methyl palmitate (C16 fatty acid methyl ester) as a reactant. Control the reaction temperature at 280℃, the hydrogen pressure at 1.5MPa, and the reactant space velocity at 1.0h. -1 The reaction was carried out for 1000 h. Gas chromatography analysis of the products showed that the conversion rate of methyl palmitate was 98.5%, and the selectivity for long-chain olefins was 92.3%. Example 3

[0026] This embodiment discloses the preparation and application of a supported sulfide-based nickel spinel catalyst. The preparation method includes the following steps: S1. Pretreatment: Take coconut shell carbon carrier and heat treat it at 300℃ (heating rate 10℃ / min) for 2.5h under nitrogen atmosphere, cool it for later use, with residual moisture of 0.2wt% and hydroxyl density of 1.7mmol / g. S2, Loading: Weigh nickel acetylacetone (organic metal complex) and chromium nitrate (Cr(NO3)3・9H2O), dissolve them in toluene at a Ni to Cr molar ratio of 1:1 (x=1.5, y=1.5), with a total metal ion concentration of 0.8 mol / L; add PEG (molecular weight 6000, structure directing agent) accounting for 7% of the total precursor mass, and stir until homogeneous; use co-precipitation method, add ammonia dropwise to the solution to adjust the pH to 9.0, stir at 40℃ for 4 h, filter after precipitation, wash until the pH of the filtrate is 7, mix evenly with coconut shell carbon support, and dry at 100℃ for 6 h to obtain Ni-Cr precursor complex (total metal mass fraction 30 wt%). S3. Calcination: Calcination was carried out at 550℃ (heating rate 6℃ / min) for 1 h under nitrogen atmosphere to obtain supported Ni-Cr-O spinel oxide. S4. Sulfidation: A mixed atmosphere of H2S and sulfur vapor (H2S volume fraction 1%) was introduced, and sulfidation was carried out at 200℃ (heating rate 4℃ / min) for 10h to obtain a sulfidated Ni-Cr-S spinel structure. S5. Activation: Activate at 220℃ (heating rate 5℃ / min) for 1.5h in a pure hydrogen atmosphere to obtain the target catalyst (active phase is Ni). 1.5 Cr 1.5 S 4.5 It exhibits a nanorod morphology, with a diameter of 15 nm and a length of 150 nm; XPS characterization shows a Ni / S surface molar ratio of 1:2.4; and a specific surface area of ​​620 m². 2 / g, pore volume 1.4cm 3 / g). Catalyst applications:

[0027] Take 5g of the above catalyst and place it in a fixed-bed reactor. Introduce n-dodecane-30wt% waste cooking oil (mainly containing C12-C18 fatty acids) as reactants. The reaction temperature is 300℃, the hydrogen pressure is 0.1MPa, and the space velocity is 1.2h⁻¹. -1 The reaction lasted for 1200 hours. Product analysis results: waste cooking oil conversion rate 96.9%, long-chain olefin selectivity 90.5%. Comparative Example 1

[0028] A conventional NiO / Al2O3 catalyst (without sulfurization treatment, Ni content 10 wt%) was used to catalyze the decarbonylation-dehydration reaction of palmitic acid under the application conditions of Example 2. The palmitic acid conversion rate was 80.5%, but after 100 hours of reaction, the methyl palmitate conversion rate decreased to 75.3%, the long-chain olefin selectivity was 62%, and the yield was only 49%. Furthermore, the catalyst exhibited significant agglomeration after the reaction, demonstrating poor stability and deactivation after 200 hours of reaction. Results Analysis

[0029] Comparing Examples 1-3 with Comparative Example 1, it can be seen that: 1) The conversion rate of the catalyst of this invention (96.9%~98.5%) is much higher than that of the existing NiO / Al2O3 catalyst (75.3% conversion rate after 100h); 2) The selectivity for long-chain olefins (90.5%~92.3%) is 1.5 times or more than that of existing catalysts; 3) Its stability is significantly better than that of existing catalysts. Its activity remains stable after 1000-1200 hours of continuous operation, while existing catalysts deactivate within 200 hours.

[0030] Any aspects not described in this invention are applicable to existing technologies.

[0031] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A supported nickel-based spinel catalyst in sulfide state, characterized in that: It includes a porous support and a sulfide-state active phase supported on the surface and / or within the pores of the porous support; the sulfide-state active phase is a sulfide with a spinel-type or spinel-like crystal structure, and its chemical composition is expressed in the general formula Ni. x M y S4 indicates that M is selected from at least one of Co, Fe, Mn, and Cr, the value of x is in the range of 0.5≤x≤1.5, and the value of y is in the range of 1.5≤y≤2.5; the total mass fraction of metal element Ni and M in the catalyst is 5wt% to 40wt%.

2. The catalyst according to claim 1, characterized in that: The porous carrier is a composite carrier composed of one or more of the following: mesoporous carbon, activated carbon, coconut shell carbon, graphitized carbon, silicon dioxide, and alumina.

3. The catalyst according to claim 1, characterized in that: The catalyst has a specific surface area of ​​150–800 m². 2 / g, pore volume 0.3~2.0cm 3 / g, the carrier has a mesopore size of 3-50nm.

4. The catalyst according to claim 1, characterized in that, The sulfurized active phase exhibits at least one of the following micromorphological forms: nanosheets, nanorods, nanoflowers, or nanoporous crystals.

5. A method for preparing a supported sulfide-type nickel-based spinel catalyst according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Pretreatment: The porous support is heat-treated in an atmosphere of nitrogen or argon at a temperature of 280-350°C for 2-3 hours. S2. Loading: A solution containing Ni source and M source is loaded onto a treated porous support by at least one of impregnation method, co-precipitation method, solvothermal method or hydrothermal method to form Ni-M precursor composite, wherein the molar ratio of metal elements in Ni source and M source is controlled to be 1:(1.8~2.2). S3. Calcination: The Ni-M precursor composite is calcined in a nitrogen atmosphere at a temperature of 250-550°C for 1-6 hours to obtain supported Ni-MO spinel oxide. S4. Sulfidation: The supported Ni-MO spinel oxide is sulfidated in a sulfur-containing atmosphere at a temperature of 200-420°C for 2-10 hours to transform the oxide into a sulfidated Ni-MS spinel or spinel-like structure. S5. Activation: The sulfided product is activated at 220-420℃ for 0.5-1.5 hours in a hydrogen atmosphere or a mixture of hydrogen and inert gas to obtain the desired catalyst.

6. The method according to claim 5, characterized in that, In step S2, the precursor is selected from nitrates, acetates or organometallic complexes, and a structure directing agent accounting for 1% to 10% of the total mass of the precursor is added during the loading process to induce the formation of a two-dimensional plate-like or three-dimensional flower-like spinel structure; the structure directing agent is at least one of hexadecyltrimethylammonium bromide, polyethylene glycol or polyvinylpyrrolidone.

7. The method according to claim 5, characterized in that, In step S4, the sulfur-containing atmosphere is a combination of H2S and H2, or H2S and sulfur vapor, or H2S and CS2, wherein the volume fraction of H2S is 1% to 10%.

8. The use of the catalyst according to any one of claims 1-4 in the preparation of long-chain olefins, characterized in that, Under the conditions of a reaction temperature of 200-350℃ and a hydrogen pressure of 0.1-3MPa, bio-based fatty acids or their derivatives are contacted with the catalyst described in any one of claims 1-4 to cause a decarbonylation-dehydration reaction to generate long-chain olefins.

9. The application according to claim 8, characterized in that, The bio-based fatty acid or its derivative is selected from at least one of fatty acids with 10 to 20 carbon atoms, fatty acid methyl esters with 10 to 20 carbon atoms, fatty acid ethyl esters with 10 to 20 carbon atoms, animal and vegetable oils or waste oils.