Nickel-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalyst preparation, and provides a nickel-based catalyst as well as a preparation method and application thereof. The nickel-based catalyst comprises a carrier and metal nickel nanoparticles loaded on the carrier; the particle size of the metallic nickel nanoparticles is (x + / -y) nm, and x is equal to 1-20, y < lt >; and 0.15 x. The nickel-based catalyst provided by the invention has the advantages of uniform active component particles, concentrated size distribution and simple preparation process; the catalyst is used in C2 fraction selective hydrogenation reaction, has high acetylene conversion activity and high ethylene selectivity, and can effectively inhibit carbon deposition and generation of green oil.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and more specifically, to a nickel-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The ethylene industry is the leading industry in the chemical industry and is crucial for the development of the national economy. Ethylene production usually adopts naphtha cracking technology, but there are trace amounts of acetylene impurities in the C2 fraction. The presence of acetylene not only poses a process safety hazard but also affects the poisoning of downstream catalysts. Therefore, it is crucial to remove trace amounts of acetylene in the C2 fraction. Through the hydrogenation process, especially the design and synthesis of high-performance selective hydrogenation catalysts, it is particularly necessary to achieve the above process. Generally speaking, for the active components of acetylene selective hydrogenation catalysts, their activity order is generally: Pd > Pt > Ni > Co > Fe > Cu. Among them, Pd-based catalysts have been studied more in past research and are also widely used in technology applications due to their relatively high hydrogenation activity; however, they also face problems and challenges such as high costs, poor ethylene selectivity, easy coking, and easy poisoning, which have an important impact on the benefits and continuous production of enterprises. As a non-noble metal, Ni-based catalysts have received attention from the academic and industrial circles in recent years due to their advantages such as low price, easy availability, high hydrogenation selectivity, strong raw material adaptability, and not easy to coke.

[0003] Existing Ni-based selective hydrogenation catalysts are generally prepared by traditional methods such as impregnation method, precipitation method, solvothermal method, etc. Although the above preparation methods have mature processes and wide applications, due to the uneven particle size of the obtained catalyst active components, the catalyst cannot achieve the expected high activity and selectivity. Therefore, how to prepare a Ni-based catalyst with uniform particle size and high dispersion of active components is an urgent problem to be solved.

[0004] For the development of Ni-based selective hydrogenation catalysts, the core is to obtain catalytically active centers with uniform particle size and high dispersion. Therefore, the demand for the development of preparation methods for high-performance catalysts is becoming increasingly urgent. Summary of the Invention

[0005] The purpose of the present invention is to provide a nickel-based catalyst, a preparation method thereof, and an application thereof, so as to solve the technical problems in the existing Ni-based selective hydrogenation catalyst preparation technology, such as uneven particle size of active components, uncontrollable particle size, and inability to achieve the expected high activity and selectivity.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a nickel-based catalyst, comprising a support and metal nickel nanoparticles supported on the support; the particle size of the metal nickel nanoparticles is (x±y) nm, where x = 1 to 20 and y < 0.15x.

[0008] The nickel-based catalyst provided by the present invention has uniform particles and a narrow size distribution.

[0009] According to some embodiments of the present invention, x = 1 to 10.

[0010] According to some embodiments of the present invention, the content of the metal nickel nanoparticles in the nickel-based catalyst is 0.1 to 10 wt%, and for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 4.5 wt%, 5 wt%, 7 wt%, 8 wt%, 10 wt%, etc.

[0011] According to some embodiments of the present invention, the support comprises at least one of alumina, silica, zirconia, titania, ceria, activated carbon, and molecular sieve.

[0012] In a second aspect, the present invention provides a method for preparing the nickel-based catalyst described in the first aspect, comprising: mixing a nickel precursor and a solvent to obtain a nickel precursor solution, forming an aerosol from the nickel precursor solution and subjecting the aerosol to a drying treatment, then introducing the dried aerosol into a combustible gas flame for pyrolysis of the nickel precursor, and then spraying it onto the support to obtain the nickel-based catalyst.

[0013] Using the method provided by the present invention to prepare the nickel-based catalyst, the preparation method is simple, the particle size of the active component of the prepared catalyst is controllable, the particle size is relatively uniform, and the catalytic performance in the hydrogenation reaction of C2 fractions is excellent.

[0014] According to some embodiments of the present invention, the nickel precursor comprises at least one of an organic nickel salt and an inorganic nickel salt.

[0015] According to some embodiments of the present invention, the organic nickel salt comprises at least one of nickel acetylacetonate, nickel tetracarbonyl, nickel formate, nickel acetate, nickel ammonium citrate, nickel oxalate, and nickel benzoate.

[0016] According to some embodiments of the present invention, the inorganic nickel salt comprises at least one of nickel nitrate, nickel chloride, nickel sulfate, and nickel carbonate.

[0017] According to some embodiments of the present invention, the solvent comprises at least one of water, alcohol components, and benzene components.

[0018] According to some embodiments of the present invention, the solvent includes an alcohol component and a benzene component.

[0019] According to some embodiments of the present invention, the volume ratio of the alcohol component to the benzene component is (1:9) to (9:1), and for example, it can be 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, etc.

[0020] According to some embodiments of the present invention, the alcohol component includes at least one of methanol, ethanol, propanol, isopropanol, butanol, and octanol.

[0021] According to some embodiments of the present invention, the benzene component includes at least one of benzene, toluene, p-xylene, o-xylene, and m-xylene.

[0022] According to some embodiments of the present invention, the preparation method includes:

[0023] S1. Mix a nickel precursor and a solvent to obtain a nickel precursor solution, and use a carrier gas to carry the nickel precursor solution to an atomizer to form an aerosol;

[0024] S2. Perform a drying treatment on the aerosol;

[0025] S3. Pass the dried aerosol into a combustible gas flame for pyrolysis reaction of the nickel precursor, and then eject it through a nozzle;

[0026] S4. Use a cooling gas to cool the airflow ejected from the nozzle;

[0027] S5. Spray the cooled airflow onto the surface of the carrier to obtain the nickel-based catalyst.

[0028] In the preparation method provided by the present invention, by using a carrier gas to carry the nickel precursor solution to an atomizer for atomization treatment, the nickel precursor solution is dispersed into uniform droplets to form an aerosol; then the aerosol is dried, and the processes of solute diffusion and droplet shrinkage occur to volatilize the solvent; then the dried aerosol is pyrolyzed in a combustible gas flame to decompose the nickel precursor into nickel oxide small particles, which are ejected through a nozzle, and after cooling treatment, they are sprayed onto the surface of the carrier, so that the nickel oxide small particles are uniformly distributed on the surface of the carrier.

[0029] In the present invention, the cooling gas generally uses a gas at room temperature.

[0030] In the present invention, the carrier generally rotates at a high speed in a high-speed rotating drum to facilitate the uniform spraying of the cooled airflow onto the surface of the carrier.

[0031] According to some embodiments of the present invention, the carrier gas is air, He, Ar, N2 at least one of

[0032] According to some embodiments of the present invention, the carrier gas flow rate is 10-200 mL / min.

[0033] According to some embodiments of the present invention, the drying temperature is 100-250 °C, preferably 150-200 °C.

[0034] According to some embodiments of the present invention, the gas flow after the cooling treatment contacts the carrier surface for 10-60 min.

[0035] According to some embodiments of the present invention, the combustible gas includes at least one of methane, ethane, ethylene, and acetylene.

[0036] According to some embodiments of the present invention, the combustion-supporting gas is air or oxygen.

[0037] According to some embodiments of the present invention, the cooling gas includes any one of air, N 2 , He, and Ar.

[0038] In a third aspect, the present invention provides the use of the nickel-based catalyst described in the first aspect or the nickel-based catalyst prepared by the preparation method described in the second aspect in selective hydrogenation, especially in the selective hydrogenation reaction of C2.

[0039] According to some embodiments of the present invention, the reaction conditions for the selective hydrogenation reaction of C2 include: the reaction temperature is 210-250 °C, the reaction pressure is 1.5-2.0 MPa, and the volume space velocity is 2000-5000 h -1 .

[0040] The beneficial effects of the present invention are at least as follows:

[0041] The active component particles of the nickel-based catalyst provided by the present invention are uniform, the size distribution is concentrated, and the preparation process is simple; when it is used in the selective hydrogenation reaction of C2 fraction, it has high acetylene conversion activity and high ethylene selectivity, and can effectively inhibit the formation of carbon deposition and "green oil". BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the HRTEM spectrum of the catalyst of Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present invention clearer, the following further describes the present invention in detail in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present patent in detail and do not limit the protection scope of the present invention in any way.

[0044] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments, and equipment used in the following examples can all be obtained through market purchases or by existing methods; the dosages of the reagents are the dosages of the reagents in conventional experimental operations unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0045] In the examples and comparative examples of the present invention, the test methods for the microscopic morphology and particle size of the catalyst are as follows:

[0046] The Tecnai G2 F20 high-definition transmission electron microscope (HRTEM) system was used to observe and detect the microscopic morphology and particle size of the catalyst. The system operates under a field emission gun with an acceleration voltage of 200 kV. High-definition images were captured and collected through a CCD camera.

[0047] The preparation process of the sample is as follows: Grind the sample powder evenly in an agate mortar, then take a small amount of the powder and disperse it in absolute ethanol, ultrasonically disperse it evenly for 30 min, and use a dropper to take 2 - 3 drops of the supernatant and drop it on a copper mesh coated with a carbon film.

[0048] The Nano Measurer software was used to measure the sizes of more than 300 randomly selected nanoparticles in the field of view to obtain the particle size distribution of the nanoparticles.

[0049] Example 1

[0050] Pseudoboehmite (provided by Shanghai Catalyst Branch of Sinopec) was dried in a dynamic oven at 120 °C for 12 h, taken out and cooled to room temperature, and then placed in a high-temperature muffle furnace, heated to 1200 °C at a heating rate of 2 °C / min and held for 8 h, taken out after natural cooling, to obtain α-Al 2 O 3 support.

[0051] Take 10 g of α-Al 2 O 3The carrier is placed in a rotating drum at the rear end of the pyrolysis reactor and rotates at a high speed of 1000 r / min. 1.38 g of nickel acetylacetonate is dissolved in a mixed solution of 50 mL of ethanol and benzene (volume ratio 1:9), stirred evenly to form a homogeneous solution, and placed in an atomized solution storage tank. The flow rate of the carrier gas He is controlled to be 100 mL / min, and the solution is carried to the atomizer to form an aerosol. Then the aerosol is brought into the pre-drying zone for drying treatment, and the temperature of the pre-drying zone is 200 °C. The dried aerosol is brought into the high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone through the carrier gas pipeline, ejected at the nozzle and quickly cooled by the cooling gas N 2 Cool down and come into full contact with the carrier in the high-speed rotating drum for 30 min to achieve uniform loading. After natural cooling, the catalyst is obtained.

[0052] Example 2

[0053] The preparation method of the catalyst refers to Example 1, the only difference is that: the mixed solution of 50 mL of ethanol and benzene (volume ratio 1:9) is replaced by the mixed solution of 50 mL of ethanol and benzene (volume ratio 5:5).

[0054] Example 3

[0055] The preparation method of the catalyst refers to Example 1, the only difference is that: the mixed solution of 50 mL of ethanol and benzene (volume ratio 1:9) is replaced by the mixed solution of 50 mL of ethanol and benzene (volume ratio 9:1).

[0056] Example 4

[0057] The preparation method of the catalyst refers to Example 1, the only difference is that: 1.38 g of nickel acetylacetonate is replaced by 0.91 g of nickel tetracarbonyl.

[0058] Example 5

[0059] The preparation method of the catalyst refers to Example 1, the only difference is that: 1.38 g of nickel acetylacetonate is replaced by 1.56 g of nickel nitrate hexahydrate.

[0060] Example 6

[0061] The preparation method of the catalyst refers to Example 1, the only difference is that: 1.38 g of nickel acetylacetonate is replaced by 0.99 g of nickel formate dihydrate.

[0062] Example 7

[0063] The preparation method of the catalyst refers to Example 1, the only difference is that: 1.38 g of nickel acetylacetonate is replaced by 1.27 g of nickel chloride hexahydrate.

[0064] Example 8

[0065] The preparation method of the catalyst refers to Example 1, with the only difference being that 1.38 g of nickel acetylacetonate is replaced by 1.71 g of nickel ammonium citrate.

[0066] Example 9

[0067] The preparation method of the catalyst refers to Example 1, with the only difference being that 50 mL of the ethanol and benzene mixture (volume ratio 1:9) is replaced by 50 mL of ethanol.

[0068] Example 10

[0069] The preparation method of the catalyst refers to Example 1, with the only difference being that 50 mL of the ethanol and benzene mixture (volume ratio 1:9) is replaced by 50 mL of benzene.

[0070] Example 11

[0071] The preparation method of the catalyst refers to Example 5, with the only difference being that 50 mL of the ethanol and benzene mixture (volume ratio 1:9) is replaced by 50 mL of distilled water.

[0072] Example 12

[0073] The preparation method of the catalyst refers to Example 1, with the only difference being that 50 mL of the ethanol and benzene mixture (volume ratio 1:9) is replaced by 50 mL of the ethanol, acetic acid, and distilled water mixture (volume ratio 4.5:4.5:1).

[0074] Comparative Example 1

[0075] Weigh 1.56 g of nickel nitrate hexahydrate, dissolve it in 50 mL of distilled water, and add 1.0 mL of dilute nitric acid until the solution becomes clear; then weigh 10 g of α-Al 2 O 3 support and add it to the above solution, stir for 6 h, let it stand and age for 6 h, and dry it overnight at 120 °C. Transfer it to a muffle furnace and heat it to 550 °C at a rate of 1 °C / min in an air atmosphere and calcine for 3 h. After naturally cooling to room temperature, the catalyst is obtained.

[0076] Comparative Example 2

[0077] The preparation method of the catalyst refers to Comparative Example 1, with the only difference being that 1.56 g of nickel nitrate hexahydrate is replaced by 1.27 g of nickel chloride hexahydrate.

[0078] Comparative Example 3

[0079] Weigh 1.38 g of nickel acetylacetonate, 10 g of α-Al 2 O 3The carrier was added to a 50 mL mixed solution of ethanol and benzene (volume ratio 1:9). Under nitrogen protection and continuous stirring, the mixed solution was heated to 320 °C at a rate of 1 °C / min and maintained for 3 h. After the reaction was completed, the reaction mixture was cooled to 60 °C under nitrogen protection, and then the reaction mixture was taken out for suction filtration. An ethanol-carbon tetrachloride solution with a volume ratio of 1:1 was prepared, and the product was washed, filtered, and dried at room temperature to obtain the catalyst.

[0080] Comparative Example 4

[0081] The preparation method of the catalyst referred to Comparative Example 3, with the only difference being that 1.38 g of nickel acetylacetonate was replaced by 0.91 g of nickel tetracarbonyl.

[0082] Comparative Example 5

[0083] 1.56 g of nickel nitrate hexahydrate was weighed and dissolved in 50 mL of distilled water. 1.0 mL of dilute nitric acid was added until the solution was clear. Then, 10 g of α-Al 2 O 3 The carrier was added to the above solution, and 50 mL of 0.1 mol / L ammonia water was added dropwise during stirring to form a precipitate, which was then filtered. After washing three times, it was dried at 120 °C for 12 h. It was placed in a muffle furnace and heated to 550 °C at a rate of 1 °C / min in an air atmosphere and calcined for 3 h. After natural cooling to room temperature, the catalyst was obtained.

[0084] Comparative Example 6

[0085] The preparation method of the catalyst referred to Comparative Example 5, with the only difference being that 1.56 g of nickel nitrate hexahydrate was replaced by 1.27 g of nickel chloride hexahydrate.

[0086] Catalyst performance evaluation

[0087] 1 g of the catalyst from each example and comparative example was weighed and loaded into a 20 mL fixed-bed reactor. Under a pure hydrogen atmosphere, a pressure of 1.5 - 2.0 MPa, and a space velocity of 2000 - 5000 h -1 The temperature was increased to 350 °C at a rate of 30 °C / h and maintained for 6 h. Then, under the reaction conditions of a pressure of 1.5 - 2.0 MPa, a space velocity of 2000 - 5000 h -1 and a temperature of 210 - 250 °C, the catalytic performance of the simulated refinery gas (gas composition: 0.01 - 0.7% acetylene, 1.5 - 3.5% hydrogen, 5 - 15% ethylene, with nitrogen as the balance gas) for the C2 fraction was tested.

[0088] The calculation formulas for acetylene conversion and ethylene selectivity are as follows:

[0089] Acetylene conversion = [acetylene (inlet) - acetylene (outlet)] / acetylene (inlet) × 100%

[0090] Ethylene selectivity = [Ethylene (outlet) - Ethylene (inlet)] / [Acetylene (inlet) - Acetylene (outlet)] × 100%

[0091] The test results of catalytic performance are shown in Table 1 as follows.

[0092] Table 1

[0093]

[0094] Note: The acetylene conversion rate (cycle) and ethylene conversion rate (cycle) in Table 1 refer to the acetylene conversion rate and ethylene conversion rate after the catalyst is recycled 5 times.

[0095] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as provided, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A nickel-based catalyst, characterized in that, it comprises a support and metal nickel nanoparticles supported on the support; the particle size of the metal nickel nanoparticles is (x±y) nm, where x = 1 to 20, preferably 1 to 10, and y < 0.15x.

2. The nickel-based catalyst according to claim 1, characterized in that, the content of the metal nickel nanoparticles in the nickel-based catalyst is 0.1 to 10 wt%; and / or, the support comprises at least one of alumina, silica, zirconia, titania, ceria, activated carbon, molecular sieve.

3. A method for preparing the nickel-based catalyst according to claim 1 or 2, characterized in that, it comprises: mixing a nickel precursor and a solvent to obtain a nickel precursor solution, forming the nickel precursor solution into an aerosol and drying the aerosol, then introducing the dried aerosol into a combustible gas flame for pyrolysis of the nickel precursor, and then spraying it onto the support to obtain the nickel-based catalyst.

4. The preparation method according to claim 3, characterized in that, the nickel precursor comprises at least one of an organic nickel salt and an inorganic nickel salt; preferably, the organic nickel salt comprises at least one of nickel acetylacetonate, nickel tetracarbonyl, nickel formate, nickel acetate, nickel ammonium citrate, nickel oxalate, nickel benzoate; and / or, the inorganic nickel salt comprises at least one of nickel nitrate, nickel chloride, nickel sulfate, nickel carbonate.

5. The preparation method according to claim 3 or 4, characterized in that, the solvent comprises at least one of water, alcohol components, benzene components, preferably comprising alcohol components and benzene components; preferably, the volume ratio of the alcohol components to the benzene components is (1:9) to (9:1); and / or, the alcohol components comprise at least one of methanol, ethanol, propanol, isopropanol, butanol, octanol; and / or, the benzene components comprise at least one of benzene, toluene, p-xylene, o-xylene, m-xylene.

6. The preparation method according to any one of claims 3-5, characterized in that, it comprises: S1. Mixing a nickel precursor and a solvent to obtain a nickel precursor solution, and using a carrier gas to carry the nickel precursor solution to an atomizer to form an aerosol; S2. Drying the aerosol; S3. Introducing the dried aerosol into a combustible gas flame for pyrolysis reaction of the nickel precursor, and then spraying it out through a nozzle; S4. Cooling the gas flow sprayed out from the nozzle with a cooling gas; S5. Spraying the cooled gas flow onto the surface of the support to obtain the nickel-based catalyst.

7. The preparation method according to claim 6, characterized in that, The carrier gas is at least one of air, He, Ar, and N 2 ; and / or, the flow rate of the carrier gas is 10 to 200 mL / min; and / or, the drying temperature is 100 to 250 °C, preferably 150 to 200 °C; and / or, the cooled gas flow contacts the surface of the support for 10 to 60 min.

8. The preparation method according to claim 6 or 7, characterized in that, the combustible gas comprises at least one of methane, ethane, ethylene, acetylene.

9. The preparation method according to any one of claims 6-8, characterized in that, The cooling gas includes any one of air, N 2 , He, and Ar.

10. Use of the nickel-based catalyst according to claim 1 or 2, or the nickel-based catalyst prepared by the preparation method according to any one of claims 3-9, in selective hydrogenation, especially in the selective hydrogenation reaction of C2.

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