Straight-chain alpha-olefin and bifunctional catalyst as well as preparation method and application of bifunctional catalyst
Through the dual-function catalyst system of Fe-M catalyst and gallium-based catalyst, the problems of low catalyst conversion, insufficient selectivity and poor stability in CO2 hydrogenation reaction are solved, and high selectivity and stable linear α-olefin preparation is achieved.
Patent Information
- Application Number
- CN202510081812.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-05-02
AI Technical Summary
The catalysts used in the CO2 hydrogenation reaction for preparing linear α-olefins have problems such as low one-way conversion, insufficient olefin selectivity and poor stability of the catalytic material.
A dual-function catalyst system of Fe-M catalyst and gallium-based catalyst is used to dissolve the Fe salt and M salt in water, stir and add dropwise with an alkaline solution, precipitate and calcinate, and physically mix it with the gallium-based catalyst to form a bifunctional catalyst.
The selectivity of α-olefins and high-carbon hydrocarbons is improved, the dispersion, activity and stability of the catalyst are enhanced, and the performance is better than that of a single iron-based catalyst.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of new material technology, and more specifically, to a bifunctional catalyst for preparing linear alpha-olefins by hydrogenating CO2, a method for preparing the catalyst, and a method for preparing linear alpha-olefins using the catalyst. Background Art
[0002] Linear α-olefins (C 4-20 ) is a high-end organic raw material, and its structural feature is that the molecular end chain has an unsaturated double bond in the normal hydrocarbon, which is widely used in the manufacture of polyethylene comonomers, high-end lubricants, pour point depressants and surfactants. At present, most straight-chain α-olefins are produced through petrochemicals (ethylene polymerization) and coal chemical routes (Fischer-Tropsch synthesis). The main methods are: (1) paraffin cracking, (2) extraction and mixed C4 separation, and (3) primary alcohol dehydration. Landau et al. [Industrial & Engineering Chemistry Research, 2017, 56 (45): 13335-56.] prepared a K / Fe-Al-O series catalyst, and achieved a total CO2 conversion rate of 89% and C5 + The product selectivity is 41%, mainly olefin products.
[0003] At present, there is still much room for improvement in the single-pass conversion rate of the reaction catalyst, olefin selectivity, and the stability of the catalytic material under CO2 hydrogenation reaction conditions. Summary of the invention
[0004] One of the purposes of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a bifunctional catalyst for preparing linear α-olefins by hydrogenation of CO2 and a preparation method thereof, as well as a method for preparing linear α-olefins by using the catalyst.
[0005] One aspect of the present invention provides a method for preparing a linear α-olefin bifunctional catalyst, the preparation method comprising: dissolving an Fe salt and an M salt in water, stirring to obtain a first solution, wherein the metal M is at least one of K, Na, Mn, Al, Zn and Cu; at room temperature, dropping an alkaline second solution into the first solution and stirring for 1 to 3 hours, after the dropping is completed, allowing the precipitate to stand, then centrifugally washing, drying and grinding, roasting the ground sample at 400 to 500° C. and cooling to room temperature, to obtain Fe-M catalyst; prepare a precursor solution, the concentration of Ga(NO3)3 in the precursor solution is 0.1-5.0 g / mL; add water to the carrier and the precursor solution, stir, shake to form a paste, grind, vacuum dry, and calcine at 400-600°C to obtain a gallium-based catalyst, wherein the carrier is at least one of gas-phase silica, silica sol, titanium dioxide, magnesium oxide and silicon-aluminum catalyst carriers; after physically mixing the Fe-M catalyst and the gallium-based catalyst in equal mass ratios, a linear α-olefin bifunctional catalyst is obtained.
[0006] In an embodiment, the molar ratio of the metal M in the M salt to the Fe in the Fe salt may be 1:1 to 1:6, and the loading amount of the metal M may be 0.5 to 3 wt %.
[0007] In an embodiment, the preparation method may include: dissolving sodium hydroxide or sodium carbonate in water, and stirring to obtain the second solution.
[0008] In an embodiment, during the process of adding the second solution dropwise to the first solution, the pH value of the solution can be maintained at 9-11.
[0009] In an embodiment, the loading amount of metal Ga in the precursor solution may be 0.5-5 wt %.
[0010] In the embodiment, the ground sample can be calcined at 400-500° C. for 3-5 hours and then naturally cooled to room temperature.
[0011] In an embodiment, in the step of obtaining the gallium-based catalyst, the calcination time at 400-600° C. can be 2-5 hours.
[0012] In an embodiment, the calcination may be performed in a muffle furnace.
[0013] According to another aspect of the present invention, a linear α-olefin bifunctional catalyst is provided. The linear α-olefin bifunctional catalyst is obtained by the preparation method as described above.
[0014] According to another aspect of the present invention, a method for preparing linear α-olefins is provided, characterized in that the method adopts the linear α-olefin bifunctional catalyst obtained by the preparation method as described above to prepare the linear α-olefins, and the method comprises: after the linear α-olefin bifunctional catalyst is loaded into the reactor, 10 to 100 wt % CO is introduced at 30 to 50 mL / min, the temperature is raised to 350 to 400° C., and reduction is performed for 4 to 8 hours; switching to pure Ar and cooling to 320 to 340° C., the flow rate of pure Ar is 30 to 50 mL / min, and then the pressure is increased to 1 to 3 MPa to introduce the reaction gas, wherein the reaction gas is H2, CO2 and Ar, and GHSV=5000 to 20000 ml·g -1 ·h -1 , react for 15 to 48 hours to obtain linear α-olefins.
[0015] Compared with the prior art, the beneficial effects of the present invention are: the catalyst prepared by the present invention has a simple preparation method, the catalyst has high dispersibility, high activity and stability, and compared with a single iron-based catalyst, the addition of a gallium catalyst improves the selectivity of α-olefins and high-carbon hydrocarbons. DETAILED DESCRIPTION
[0016] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0017] At present, there is still a lot of room for improvement in the single-pass conversion rate of the reaction catalyst, olefin selectivity, and stability of the catalytic material under CO2 hydrogenation reaction conditions in the related technologies. Therefore, it is necessary to develop a preparation method of a bifunctional catalyst for CO2 hydrogenation to prepare linear α-olefins.
[0018] As mentioned above, the first aspect of the present invention provides a method for preparing a linear α-olefin bifunctional catalyst, the preparation method comprising:
[0019] S1. Dissolve Fe salt and M salt in water, and stir to obtain a first solution, wherein the metal M is one of K, Na, Mn, Al, Zn and Cu.
[0020] S2. At room temperature, add the alkaline second solution dropwise to the first solution and stir for 1 to 3 hours. After the addition is completed, let the precipitate stand, then centrifuge and wash it, grind it after drying, and calcine the ground sample at 400 to 600°C and cool it to room temperature to obtain a Fe-M catalyst.
[0021] S3. Prepare a precursor solution, wherein the concentration of Ga(NO3)3 in the precursor solution is 0.1-5.0 g / mL.
[0022] S4. Add water to the carrier and the precursor solution, stir, shake to form a paste, grind, vacuum dry, and calcine at 400-600° C. to obtain a gallium-based catalyst, wherein the carrier is one of fumed silica, silica sol, titanium dioxide, magnesium oxide and silicon-aluminum catalyst carriers.
[0023] S5. Physically mix the Fe-M catalyst and the gallium-based catalyst in equal mass ratios to obtain a linear α-olefin bifunctional catalyst.
[0024] The catalyst synthesized according to the method of the present invention has a simple preparation method, and the catalyst has high dispersibility, high activity and stability. Compared with a single iron-based catalyst, the addition of a gallium catalyst improves the selectivity of α-olefins and higher carbon hydrocarbons.
[0025] In step S1, the molar ratio of metal M in the M salt to Fe in the Fe salt can be 1:1 to 1:6, and the loading amount of metal M is 0.5 to 3 wt %. Here, if the loading amount is too high or too low, it will result in low selectivity or conversion rate.
[0026] First, an Fe-based catalyst is prepared, and then Ga is impregnated thereon according to the loading amount. Preferably, the molar ratio of the metal M in the M salt to the Fe in the Fe salt can be 1:3 to 1:5, and the loading amount of the metal M is 1 to 2 wt%.
[0027] In step S2, the second solution is added dropwise to the first solution, and the pH value of the solution is maintained at 9 to 11. Here, the preparation process is to maintain weak alkalinity and co-precipitation preparation.
[0028] Optionally, the preparation method may further include: dissolving sodium hydroxide or sodium carbonate in water, and stirring to obtain a second solution.
[0029] In step S2, the powder is ground into powder, which is then calcined more fully.
[0030] The ground sample is calcined at 400-500°C for 3-5h and then cooled to room temperature naturally or at a rate of 10°C / min.
[0031] In step S3, the loading amount of metal Ga in the precursor solution can be 0.5-5 wt %. Here, if the concentration is too high, too little precursor solution is added and the dispersion is not good, and if the concentration is too low, too much is added and the preparation process becomes too thin, maintaining a paste effect.
[0032] In step S4, in the step of obtaining the gallium-based catalyst, the calcination time is 2 to 5 hours at 400 to 600° C. Here, if the calcination temperature is too high, agglomeration occurs.
[0033] In an exemplary embodiment, the method for preparing the linear α-olefin bifunctional catalyst of the present invention may include:
[0034] Preparation of Fe-M based catalysts:
[0035] S1. Weigh a certain amount of Fe salt (ferric chloride, ferric nitrate) and M salt (molar ratio M:Fe=1:1-1:6) and dissolve them in water, stirring to obtain solution A;
[0036] S2. Weigh a certain amount of sodium hydroxide or sodium carbonate and dissolve it in water, stirring to obtain solution B;
[0037] S3. At room temperature, use a constant flow pump to add solution B to solution A (maintaining the solution pH = 9-11) and stir for 1-3 hours. After the addition is completed, let the precipitate stand for 2-4 hours, then centrifuge and wash the sample, grind it after drying, put the ground sample into a muffle furnace, roast it at 400-500°C for 3-5 hours, cool it to room temperature, and take it out to obtain the Fe-M catalyst.
[0038] Preparation of gallium-based catalysts :
[0039] S1. Weigh a certain amount of gallium nitrate, add water to dissolve it in a volumetric flask to make a precursor solution, the concentration of Ga(NO3)3 in the precursor solution is 0.1-5.0 g / mL;
[0040] S2. Weigh a certain amount of carrier (fumed silica, silica sol, titanium dioxide, magnesium oxide, silicon-aluminum catalyst carrier) and the precursor solution obtained in step S1, ensure that the loading amount of metal Ga (the mass percentage of metal in the carrier) is 0.5-5wt%, add water and stir, shake to form a paste, grind, vacuum dry, and calcine in a muffle furnace at 400-600° C. for 2-5h, collect the calcined sample, and obtain a gallium-based catalyst.
[0041] According to another aspect of the present invention, a linear alpha-olefin bifunctional catalyst is provided. In an exemplary embodiment, the catalyst is obtained by the preparation method as described above. The linear alpha-olefin bifunctional catalyst is an iron-based catalyst and a gallium-based catalyst. Iron-based catalyst: Fe-M (metal M is K, Na, Mn, Al, Zn, Cu), molar ratio M:Fe=1:1~1:6, metal M (mass percentage of Fe) loading is 0.5~3wt%; Gallium-based catalyst: the carrier is fumed silica, silica sol, titanium dioxide, magnesium oxide, silicon-aluminum catalyst carrier, and the metal gallium (Ga) loading (mass percentage of metal to carrier) is 0.5~5wt%.
[0042] The linear α-olefin bifunctional catalyst according to the present invention can be used for preparing linear α-olefin by CO2 hydrogenation.
[0043] According to another aspect of the present invention, in an exemplary embodiment, a method for preparing linear α-olefins is provided, wherein the method uses a linear α-olefin bifunctional catalyst obtained by the preparation method as described above to prepare linear α-olefins, and the method comprises: after the linear α-olefin bifunctional catalyst is loaded into a reactor, 10 to 100 wt % CO is introduced at 30 to 50 mL / min, the temperature is raised to 350 to 400° C., and reduction is performed for 4 to 8 h (for example, reduction for 5 h); switching to pure Ar and cooling to 320 to 340° C., the flow rate of pure Ar is 30 mL / min, and then the pressure is increased to 2 MPa and a reaction gas is introduced, wherein the reaction gas is H2, CO2 and Ar, H2:CO2:Ar=3:1:4, H2:CO2=1 to 5, and this performance is measured under the same conditions for comparison of several catalysts, GHSV (gas hourly space velocity) = 5000 to 20000 ml·g -1 ·h -1 (For example, GHSV = 10000 ml g -1 ·h -1 ), react for 15 to 48 hours (for example, react for 20 hours) to obtain a linear α-olefin.
[0044] In order to better understand the above exemplary embodiments of the present invention, they are further described below with reference to specific examples.
[0045] Example 1
[0046] S1. Weigh 5 g FeCl2·4H2O and 2.2 g Zn(CH3COO)2·2H2O (molar ratio M:Fe=1:3) and dissolve them in water. Stir to obtain solution A.
[0047] S2, weigh 12g of sodium hydroxide and dissolve it in water, stirring to obtain solution B;
[0048] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 1 hour. After the addition was completed, the precipitate was allowed to stand for 2 hours. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 400°C for 3 hours, cooled to room temperature, and taken out to obtain the Fe-Zn catalyst.
[0049] Preparation of Gallium-based Catalysts:
[0050] S1. Weigh 10 g of gallium nitrate, add water to dissolve it in a 10 mL volumetric flask to make a precursor solution. The concentration of Ga(NO3)3 in the precursor solution is 1.0 g / mL.
[0051] S2. Weigh 3 g of fumed silica and 0.01 mL of the precursor solution obtained in step S1.1, ensuring that the loading amount of metal Ga (the mass percentage of metal in the carrier) is 1 wt %. After stirring with a glass rod, add water and shake to form a paste. Grind and vacuum dry, and calcine in a muffle furnace at 400°C for 2 h. Collect the calcined sample to obtain a gallium-based catalyst, recorded as 1% Ga / SiO2.
[0052] Example 2
[0053] S1. Weigh 10g FeCl2·4H2O and 1.4g NaNO3 (molar ratio M:Fe=1:3) and dissolve them in water. Stir to obtain solution A.
[0054] S2, weigh 12g of sodium carbonate and dissolve it in water, stirring to obtain solution B;
[0055] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 2 h. After the addition was completed, the precipitate was allowed to stand for 3 h. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 500 °C for 3 h until it cooled to room temperature, and then taken out to obtain the Fe-Na catalyst.
[0056] Preparation of Gallium-based Catalysts:
[0057] S1. Weigh 10 g of gallium nitrate, add water to dissolve it in a 10 mL volumetric flask to make a precursor solution. The concentration of Ga(NO3)3 in the precursor solution is 1.0 g / mL.
[0058] S2. Weigh 3 g of fumed silica and 0.01 mL of the precursor solution obtained in step S1.1, ensuring that the loading amount of metal Ga (the mass percentage of metal in the carrier) is 1 wt%. After stirring with a glass rod, add water and shake to form a paste. Grind and vacuum dry, and calcine in a muffle furnace at 600°C for 2 h. Collect the calcined sample to obtain a gallium-based catalyst, recorded as 1 wt% Ga / SiO2.
[0059] Example 3
[0060] S1. Weigh 15g Fe(NO3)3·9H2O and 2g KNO3 (molar ratio M:Fe=1:4) and dissolve them in water. Stir to obtain solution A.
[0061] S2, weigh 20g of sodium hydroxide and dissolve it in water, stirring to obtain solution B;
[0062] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 2 h. After the addition was completed, the precipitate was allowed to stand for 2 h. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 500 °C for 3 h until it cooled to room temperature, and then taken out to obtain a Fe-K catalyst.
[0063] Preparation of Gallium-based Catalysts:
[0064] S1. Weigh 15 g of gallium nitrate, add water to dissolve it in a 10 mL volumetric flask to make a precursor solution. The concentration of Ga(NO3)3 in the precursor solution is 1.5 g / mL.
[0065] S2. Weigh 5 g of titanium dioxide and 0.07 mL of the precursor solution obtained in step S1.1, ensuring that the loading amount of metal Ga (the mass percentage of metal in the carrier) is 2 wt%. After stirring with a glass rod, add water and shake to form a paste. Grind and vacuum dry, and calcine in a muffle furnace at 600°C for 2 h. Collect the calcined sample to obtain a gallium-based catalyst, recorded as 2 wt% Ga / TiO2.
[0066] Example 4
[0067] S1. Weigh 15g Fe(NO3)3·9H2O and 2g KNO3 (molar ratio M:Fe=1:4) and dissolve them in water. Stir to obtain solution A.
[0068] S2, weigh 20g of sodium hydroxide and dissolve it in water, stirring to obtain solution B;
[0069] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 2 h. After the addition was completed, the precipitate was allowed to stand for 2 h. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 500 °C for 3 h until it cooled to room temperature, and then taken out to obtain a Fe-K catalyst.
[0070] Preparation of Gallium-based Catalysts:
[0071] S1. Weigh 15 g of gallium nitrate, add water to dissolve it in a 10 mL volumetric flask to make a precursor solution. The concentration of Ga(NO3)3 in the precursor solution is 1.5 g / mL.
[0072] S2. Weigh 5 g of silicon-aluminum catalyst carrier and 0.07 mL of the precursor solution obtained in step S1.1, ensuring that the loading amount of metal Ga (the mass percentage of metal in the carrier) is 3 wt%. After stirring with a glass rod, add water and shake to form a paste. Grind and vacuum dry, and calcine in a muffle furnace at 400°C for 2 h. Collect the calcined sample to obtain a gallium-based catalyst, recorded as 2 wt% Ga / Si-Al.
[0073] Comparative Example 1
[0074] S1. Weigh 5 g FeCl2·4H2O and 2.2 g Zn(CH3COO)2·2H2O (molar ratio M:Fe=1:3) and dissolve them in water. Stir to obtain solution A.
[0075] S2, weigh 12g of sodium hydroxide and dissolve it in water, stirring to obtain solution B;
[0076] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 1 hour. After the addition was completed, the precipitate was allowed to stand for 2 hours. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 400°C for 3 hours, cooled to room temperature, and taken out to obtain the Fe-Zn catalyst.
[0077] Comparative Example 2
[0078] S1. Weigh 10 g FeCl2·4H2O and 1.4 g NaNO3 (molar ratio M:Fe=1:3) and dissolve them in water. Stir to obtain solution A.
[0079] S2, weigh 12g of sodium carbonate and dissolve it in water, stirring to obtain solution B;
[0080] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 2 h. After the addition was completed, the precipitate was allowed to stand for 3 h. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 500 °C for 3 h until it cooled to room temperature, and then taken out to obtain the Fe-Na catalyst.
[0081] Comparative Example 3
[0082] S1. Weigh 15g Fe(NO3)3·9H2O and 2g KNO3 (molar ratio M:Fe=1:4) and dissolve them in water. Stir to obtain solution A.
[0083] S2, weigh 20g of sodium hydroxide and dissolve it in water, stirring to obtain solution B;
[0084] S3. At room temperature, solution B was added dropwise to solution A using a constant flow pump (keeping the solution pH at 9-11) and stirred for 2 h. After the addition was completed, the precipitate was allowed to stand for 2 h. The sample was then centrifuged and washed, dried and ground. The ground sample was placed in a muffle furnace, calcined at 500 °C for 3 h until it cooled to room temperature, and then taken out to obtain a Fe-K catalyst.
[0085] Evaluation example
[0086] Catalyst performance test
[0087] First, the catalyst in the above example was pressed into particles, and particles of 150 to 250 μm were screened and retained. Then, the Fe-M catalyst and the Ga catalyst were physically mixed in equal mass ratios (Fe-Zn + 1% Ga / SiO2 as recorded in Table 1), and the catalyst bed position was fixed by a thin layer of quartz wool to ensure that the catalyst bed was located in the constant temperature section of the stainless steel reactor. The specific experimental conditions are as follows: After 0.1g of the catalyst was loaded into the reactor, 10% CO (50ml / min) was introduced, the temperature was raised to 350°C, and reduced for 5h, then switched to pure Ar (30ml / min) and cooled to 320°C, the pressure was raised to 2MPa, and the reaction gas (H2:CO2:Ar=3:1:4, GHSV=10000ml·g-1·h-1) was introduced, and the reaction was carried out for 20h. The experimental results are shown in Table 1.
[0088] Table 1 Evaluation of reactions with different catalysts
[0089]
[0090] It can be seen from Table 1 that compared with Fe-Zn, Fe-Na, and Fe-K catalysts, the CO2 conversion rate and C2 ＝ -C4 ＝ The selectivity was improved, and C5 + The selectivity increased to about 40%, indicating that the bifunctional catalyst improved the selectivity of α-olefins and higher carbon hydrocarbons.
[0091] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A method for preparing a linear α-olefin bifunctional catalyst, characterized in that: The preparation method comprises: Dissolving Fe salt and M salt in water and stirring to obtain a first solution, wherein the metal M is at least one of K, Na, Mn, Al, Zn and Cu; At room temperature, the alkaline second solution is added dropwise to the first solution and stirred for 1 to 3 hours. After the addition is completed, the precipitate is allowed to stand, then centrifuged and washed, dried and then ground. The ground sample is calcined at 400 to 500° C. and cooled to room temperature to obtain a Fe-M catalyst. Prepare a precursor solution, wherein the concentration of Ga(NO3)3 in the precursor solution is 0.1-5.0 g / mL; The carrier and the precursor solution are stirred with water, shaken to form a paste, ground, vacuum dried, and calcined at 400-600° C. to obtain a gallium-based catalyst, wherein the carrier is at least one of fumed silica, silica sol, titanium dioxide, magnesium oxide, and silicon-aluminum catalyst carriers; After physically mixing the Fe-M catalyst and the gallium-based catalyst in equal mass ratio, a linear α-olefin bifunctional catalyst is obtained.
2. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: The molar ratio of the metal M in the M salt to the Fe in the Fe salt is 1:1 to 1:6, and the loading amount of the metal M is 0.5 to 3 wt %.
3. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: The preparation method comprises: dissolving sodium hydroxide or sodium carbonate into water, and stirring to obtain the second solution.
4. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: During the process of adding the second solution dropwise to the first solution, the pH value of the solution is maintained at 9-11.
5. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: The loading amount of metal Ga in the precursor solution is 0.5-5wt%.
6. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: The ground samples were calcined at 400-500°C for 3-5 h and then naturally cooled to room temperature.
7. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: In the step of obtaining the gallium-based catalyst, the calcination time at 400-600° C. is 2-5 hours.
8. The method for preparing a linear α-olefin bifunctional catalyst according to claim 1, characterized in that: The calcination is carried out in a muffle furnace.
9. A linear α-olefin bifunctional catalyst, characterized in that: The linear α-olefin bifunctional catalyst is obtained by the preparation method described in any one of claims 1 to 8.
10. A method for preparing linear α-olefins, characterized in that: The preparation method uses the linear α-olefin bifunctional catalyst obtained by the preparation method according to any one of claims 1 to 8 to prepare the linear α-olefin, and the preparation method comprises: After loading the linear α-olefin bifunctional catalyst into the reactor, 10-100 wt% CO was introduced at 30-50 mL / min, the temperature was raised to 350-400°C, and the reduction was performed for 4-8 hours; Switch to pure Ar and cool to 320-340°C, the flow rate of pure Ar is 30-50 mL / min, then increase the pressure to 1-3 MPa and introduce the reaction gas, which is H2, CO2 and Ar, GHSV = 5000-20000 ml·g -1 ·h -1 , react for 15 to 48 hours to obtain linear α-olefins.