Supported C2 selective hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a supported C2 selective hydrogenation catalyst as well as a preparation method and application thereof. The catalyst comprises a carrier and an active component, the active component is Ni-Fe species, the nano-particle size of the active component is (x + / -y) nm, and x is equal to 2-5, y < lt >; and 0.20 x. The catalyst provided by the invention is used in a C2 fraction selective hydrogenation reaction, and compared with the existing catalyst, the catalyst provided by the invention has higher acetylene conversion activity and ethylene selectivity and better reuse stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and more specifically, to a supported C2 selective hydrogenation catalyst, its preparation method, and its application. Background Technology

[0002] Ethylene is crucial to national economic development. Typically, ethylene production utilizes naphtha thermal cracking technology; however, trace amounts of acetylene impurities exist in the C2 fraction, posing a significant safety hazard and poisoning downstream catalysts. Therefore, removing trace amounts of acetylene from the C2 fraction is essential.

[0003] Designing and synthesizing highly active and selective C2 hydrogenation catalysts can effectively solve the above problems. Generally, the activity order of the active components in acetylene selective hydrogenation catalysts is: Pd > Pt > Ni > Co > Fe > Cu. Pd-based catalysts have high hydrogenation activity, so they have been extensively studied and widely applied in the past. CN1736589A discloses a Pd / γ-Al2O3 selective hydrogenation catalyst prepared by a complete adsorption impregnation method, but this catalyst is prone to acetylene hydrogenation dimerization during use. CN101433845A discloses an unsaturated hydrocarbon selective hydrogenation catalyst and its preparation method. This catalyst uses alumina as a support and palladium as the active component. The catalyst's resistance to impurities and coking is improved by adding rare earth and alkaline earth metals and fluorine, but the selectivity of this catalyst is not ideal. It can be seen that Pd-based catalysts face problems and challenges such as high cost, poor ethylene selectivity, easy coking, and easy poisoning, which have an important impact on the efficiency and continuous production of enterprises.

[0004] In recent years, non-precious metal catalysts such as Fe, Co, Ni, and Cu have gained attention from academia and industry due to their advantages such as low cost, easy availability, strong adaptability to raw materials, and resistance to coking. Traditional Fe, Co, Ni, and Cu-based selective hydrogenation catalysts are generally prepared by impregnation, precipitation, or solvothermal methods. Although these preparation methods are mature and widely used, their catalytic performance needs further improvement due to issues such as the non-uniformity of the active component particles. Summary of the Invention

[0005] The purpose of this invention is to provide a supported C2 selective hydrogenation catalyst, its preparation method, and its application, in order to solve the problems of poor performance of existing C2 selective hydrogenation catalysts, which result in low acetylene conversion and low selectivity.

[0006] The first aspect of the present invention provides a supported C2 selective hydrogenation catalyst, comprising a support and an active component, wherein the active component is a Ni-Fe species and the nanoparticle size of the active component is (x±y) nm, wherein x=2~5 and y<0.20x.

[0007] In this invention, the nanoparticle size of the active component in the catalyst is (x±y) nm, where x=3~5 and y<0.20x, indicating that the nanoparticles are small in size and have a narrow distribution.

[0008] Furthermore, the molar ratio of Ni to Fe in the catalyst is 0.25 to 6:1, preferably 0.5 to 5:1, for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0009] Furthermore, in the catalyst, based on the mass of the catalyst, the mass content of the active component, calculated as elemental metal, is 0.1 to 10 wt%, 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.

[0010] Furthermore, in the catalyst, the support is selected from at least one of α-Al2O3, SiO2, ZrO2, TiO2, CeO2, activated carbon, and molecular sieve, preferably α-Al2O3.

[0011] Furthermore, in the catalyst, the mass content of the support is 90-99.9 wt%, based on the mass of the catalyst.

[0012] Furthermore, based on the C2H4-TPD peak area of ​​Ni / α-Al2O3, the relative peak area ratio of the C2H4-TPD of the catalyst is 0.8–1.0, preferably 0.79–0.91 (the C2H4-TPD peak area of ​​the Ni / α-Al2O3 catalyst prepared by flame jet pyrolysis is denoted as 1.0). The inventors have found that, compared to the Ni / α-Al2O3 catalyst, the catalyst exhibits a weaker adsorption capacity for ethylene, thus preventing over-hydrogenation in C2 selective hydrogenation and improving ethylene selectivity.

[0013] Furthermore, the apparent activation energy of the catalyst is 37.0–45.0 kJ / mol, preferably 37.9–42.0 kJ / mol. The inventors have discovered that the catalyst provided by this invention has a lower activation energy for acetylene, resulting in a higher conversion rate for acetylene.

[0014] Furthermore, the Ni-Fe species in the catalyst exist in the form of metal oxidation state.

[0015] A second aspect of the present invention provides a method for preparing the above-mentioned supported C2 selective hydrogenation catalyst, comprising:

[0016] The metal precursor solution is prepared by mixing a metal precursor salt and a solvent, which is then vaporized to form an aerosol. After drying and pyrolysis, the aerosol is sprayed onto the surface of a support to obtain the catalyst precursor.

[0017] Furthermore, the metal precursor includes at least one of an organometallic salt and an inorganic metal salt; the organometallic salt includes at least one of an acetylacetone metal salt, a carbonyl metal salt, a formic acid metal salt, an acetate metal salt, an ammonium citrate metal salt, an oxalate metal salt, and a benzoate metal salt; the inorganic metal salt includes at least one of a nitrate metal salt, a chloride metal salt, a sulfate metal salt, and a carbonate metal salt.

[0018] Furthermore, the metal in the metal precursor includes a first metal component and a second metal component, wherein the first metal component is Ni and the second metal component is Fe.

[0019] Furthermore, based on the elemental metal, the molar ratio of the first metal component to the second metal component is 0.25 to 6:1, preferably 0.5 to 5:1.

[0020] Further, the solvent includes at least one of water, an alcohol component, and a benzene component, preferably an alcohol component and / or a benzene component. When the solvent is an alcohol component and a benzene component, the volume ratio of the alcohol component to the benzene component is (1:9) to (9:1), for example, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, etc. The alcohol component includes at least one of methanol, ethanol, propanol, isopropanol, butanol, and octanol. The benzene component includes at least one of benzene, toluene, p-xylene, o-xylene, and m-xylene.

[0021] Furthermore, the process of vaporization to form an aerosol specifically involves: using a carrier gas to carry the metal precursor solution to an atomizer for atomization to form an aerosol. The carrier gas is at least one of air, He, Ar, and N2; the carrier gas flow rate is 10–200 mL / min; the atomization process disperses the metal precursor solution into uniform droplets, forming an aerosol.

[0022] Furthermore, the drying process involves solute diffusion and droplet shrinkage, which can evaporate the solvent.

[0023] Furthermore, the drying temperature is 100–250°C, preferably 150–200°C, and the drying time is 4–24 hours, preferably 8–12 hours.

[0024] Furthermore, the pyrolysis treatment specifically involves passing the dried aerosol into a combustible gas flame for pyrolysis. The pyrolysis treatment decomposes the metal precursor into small metal oxide particles, which are then cooled and sprayed onto the carrier surface, allowing the metal oxide particles to be evenly distributed on the carrier surface.

[0025] Furthermore, during the injection process, it is preferable to use cooling gas to cool the gas flow ejected from the nozzle, and then spray the cooled gas flow onto the surface of the carrier to obtain the metal catalyst.

[0026] Furthermore, the catalyst support is preferably rotated at high speed in a high-speed rotating drum, which facilitates the uniform spraying of the cooled airflow onto the support surface.

[0027] Furthermore, the cooled airflow is in contact with the carrier surface for 10 to 60 minutes.

[0028] Furthermore, the cooling gas includes any one of air, N2, He, and Ar.

[0029] Furthermore, the combustible gas includes at least one of methane, ethane, ethylene, and acetylene.

[0030] Furthermore, the combustible gas also includes an oxidizing agent, preferably air or oxygen.

[0031] Furthermore, before application, the catalyst needs to undergo reduction treatment under a reducing atmosphere. The reduction conditions are: hydrogen atmosphere, pressure 1.5–2.0 MPa, and space velocity 2000–5000 h⁻¹. -1 Under these conditions, the temperature is increased to 320–380℃ at a heating rate of 10–35℃ / h for reduction treatment.

[0032] The third aspect of the present invention provides the application of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in selective hydrogenation, especially selective hydrogenation of C2.

[0033] Furthermore, the selective hydrogenation reaction of C2 involves contacting the raw materials acetylene and hydrogen with the above-mentioned catalyst to carry out a selective hydrogenation reaction, thereby obtaining the product ethylene.

[0034] Furthermore, the reaction conditions for the selective hydrogenation reaction of C2 include: a reaction temperature of 210–250 °C, a reaction pressure of 1.5–2.0 MPa, and a volume hourly space velocity of 2000–5000 h⁻¹. -1 .

[0035] The beneficial effects of this invention are at least as follows:

[0036] The inventors discovered that the Ni-Fe based catalyst provided by this invention has a strong synergistic effect between the two components. Moreover, the active component particles are not only uniform in size but also small in size, eliminating the problem of low activity caused by agglomeration and exhibiting good stability. At the same time, the catalyst provided by this invention has low ethylene adsorption and strong acetylene activation ability. When used in the selective hydrogenation reaction of C2 fraction, it has higher acetylene conversion activity and ethylene selectivity compared to existing catalysts, and its stability after repeated use is better.

[0037] The preparation method described in this invention involves pre-introducing, modulating, and optimizing the type of precursor salt, and employing a flame jet pyrolysis method. The precursor salt and solvent are mixed to obtain a precursor solution, which is then treated to form an aerosol. This aerosol is subsequently dried and pyrolyzed in a combustible gas flame, and then sprayed onto a support to obtain a catalyst. The method of this invention is simple and reproducible. The resulting catalyst exhibits outstanding catalytic activity and product selectivity in the selective hydrogenation reaction of C2 fractions, and demonstrates high stability, providing an important reference for large-scale pilot-scale application. Attached Figure Description

[0038] Figure 1 The C2H4-TPD spectra of the catalysts prepared in Example 1 and Comparative Example 4 are shown. Detailed Implementation

[0039] The technical solution of the present invention will be further illustrated below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0040] In this invention, the C2H4-TPD chemisorption test method of the catalyst is as follows: The chemisorption performance of the sample is quantitatively tested using an Autochem 2920 chemisorption analyzer. 0.5g of sample is placed in a U-tube, and the sample is reduced in situ at 350℃ in an H2 atmosphere for 2 hours. After cooling to 30℃, C2H4 is introduced, and adsorption is performed for 30 minutes. Then, the sample is purged with He gas for 15 minutes. Subsequently, the temperature is increased to 800℃ at a rate of 10℃ / min under He atmosphere. The desorption peak of C2H4 is detected using a thermal conductivity detector (TCD), and the peak area is calculated by integration. In this invention, the C2H4-TPD peak area of ​​the Ni / α-Al2O3 catalyst prepared by flame jet pyrolysis is used as a reference to obtain the relative peak area ratio of C2H4-TPD for the catalyst. This ratio reflects the adsorption capacity of the catalyst for ethylene.

[0041] In this invention, the formulas for calculating the acetylene conversion rate and ethylene selectivity of the reaction are as follows:

[0042] Wherein, acetylene conversion rate, % = [acetylene (inlet) - acetylene (outlet)] / acetylene (inlet) × 100%;

[0043] Among them, ethylene selectivity, % = [ethylene (outlet) - ethylene (inlet)] / [acetylene (inlet) - acetylene (outlet)] × 100%.

[0044] Example 1

[0045] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0046] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate (Ni / Fe molar ratio 1:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0047] Example 2

[0048] The catalyst was prepared according to Example 1, except that 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate were replaced with 0.50g of nickel nitrate hexahydrate and 1.38g of ferric nitrate hexahydrate. The specific preparation process is as follows:

[0049] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0050] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.50g of nickel nitrate hexahydrate and 1.38g of ferric nitrate hexahydrate (Ni / Fe molar ratio 1:2) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0051] Example 3

[0052] The catalyst was prepared according to Example 1, except that 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate were replaced with 1.28g of nickel nitrate hexahydrate and 0.36g of ferric nitrate hexahydrate. The specific preparation process is as follows:

[0053] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0054] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 1.28g of nickel nitrate hexahydrate and 0.36g of ferric nitrate hexahydrate (Ni / Fe molar ratio 5:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas line. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0055] Example 4

[0056] The catalyst was prepared according to Example 1, except that 50 mL of water was replaced with a mixed solution of 40 mL methanol and 10 mL benzene. The specific preparation process is as follows:

[0057] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0058] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate (Ni / Fe molar ratio 1:1) were dissolved in a mixed solution of 40mL methanol and 10mL benzene, stirred until homogeneous, and placed in an atomizing solution storage tank. The flow rate of carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas line, sprayed out at the nozzle, and rapidly cooled by cooling gas N₂. The aerosol then came into full contact with the support in the high-speed rotating drum for 30min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0059] Example 5

[0060] The catalyst was prepared according to Example 1, except that the contact time between the cooling gas N2 and the support in the rotating drum was replaced with He gas for 60 minutes instead of 30 minutes. The specific preparation process is as follows:

[0061] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0062] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate (Ni / Fe molar ratio 1:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline. It was sprayed out at the nozzle and rapidly cooled by the cooling gas He, then brought into full contact with the support in the high-speed rotating drum for 60min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0063] Example 6

[0064] The catalyst was prepared according to Example 1, except that the α-Al₂O₃ support was replaced with activated carbon. The specific preparation process is as follows:

[0065] 10g of activated carbon support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate (Ni / Fe molar ratio 1:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12 hours. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline. It was sprayed out at the nozzle and rapidly cooled by N2 cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30 minutes to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0066] Example 7

[0067] The catalyst was prepared according to Example 1, except that 0.75g of nickel nitrate hexahydrate and 1.04g of ferric nitrate nonahydrate were replaced with 0.29g of nickel nitrate hexahydrate and 1.24g of ferric nitrate hexahydrate. The specific preparation process is as follows:

[0068] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0069] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.29g of nickel nitrate hexahydrate and 1.24g of ferric nitrate hexahydrate (Ni / Fe molar ratio 1:4) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone for drying at 200℃ for 12h. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30min to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0070] Comparative Example 1

[0071] Weigh 1.15 g of nickel nitrate hexahydrate and 0.53 g of ferric nitrate hexahydrate, dissolve them in 50 mL of distilled water, and add 1.0 mL of dilute nitric acid until the solution is clear. Then weigh 10 g of the α-Al₂O₃ support prepared in Example 1 and add it to the above solution. Stir for 6 h, allow to stand for aging for 6 h, and dry overnight at 120 °C. Transfer to a muffle furnace and calcine at 550 °C for 3 h under air atmosphere at a rate of 1 °C / min. After naturally cooling to room temperature, the catalyst is obtained.

[0072] Comparative Example 2

[0073] Weigh 1.15 g of nickel nitrate hexahydrate and 0.53 g of ferric nitrate hexahydrate, dissolve them in 50 mL of distilled water, and add 1.0 mL of dilute nitric acid until the solution is clear. Then weigh 10 g of the α-Al₂O₃ support prepared in Example 1 and add it to the above solution. While stirring, add 50 mL of 0.1 mol / L ammonia water dropwise. After precipitating, filter the solution, wash it three times, and dry it at 120 °C for 12 h. Place it in a muffle furnace, heat it to 550 °C at 1 °C / min under air atmosphere, calcine it for 3 h, and then allow it to cool naturally to room temperature to obtain the catalyst.

[0074] Comparative Example 3

[0075] 1.01 g of nickel acetylacetone, 0.23 g of iron acetylacetone, and 10 g of the α-Al₂O₃ support prepared in Example 1 were weighed and added to 50 mL of a mixture of ethanol and benzene (volume ratio 1:9). Under nitrogen protection and continuous stirring, the mixture was heated to 320 °C at 1 °C / min and maintained for 3 h. After the reaction was completed, the solution was cooled to 60 °C under nitrogen protection and then filtered. A 1:1 volume ratio ethanol-carbon tetrachloride solution was prepared, and the solution was washed, filtered, and dried at room temperature to obtain the catalyst.

[0076] Comparative Example 4

[0077] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0078] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 1.56g of nickel nitrate hexahydrate was dissolved in 50mL of water and stirred until a homogeneous solution was formed, which was then placed in an atomizing solution storage tank. The flow rate of carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone at a temperature of 200℃ for drying. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline, sprayed out at the nozzle, and rapidly cooled by cooling gas N₂. The aerosol then came into full contact with the support in the high-speed rotating drum for 30 minutes to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0079] Comparative Example 5

[0080] The catalyst was prepared using the same method as in Comparative Example 4, except that 1.56 g of nickel nitrate hexahydrate was replaced with 2.02 g of ferric nitrate nonahydrate. The specific preparation process is as follows:

[0081] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0082] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 2.02g of ferric nitrate nonahydrate was dissolved in 50mL of water and stirred until a homogeneous solution was formed, which was then placed in an atomizing solution storage tank. The flow rate of carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone at a temperature of 200℃ for drying. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas pipeline, sprayed out at the nozzle, and rapidly cooled by cooling gas N₂. The aerosol then came into full contact with the support in the high-speed rotating drum for 30 minutes to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0083] Comparative Example 6

[0084] The catalyst was prepared using the same method as in Comparative Example 4, except that 1.56 g of nickel nitrate hexahydrate was replaced with 0.75 g of nickel nitrate hexahydrate and 0.63 g of copper nitrate trihydrate. The specific preparation process is as follows:

[0085] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0086] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.75g of nickel nitrate hexahydrate and 0.63g of copper nitrate trihydrate (Ni / Cu molar ratio 1:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone at 200℃ for drying. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas line. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30 minutes to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0087] Comparative Example 7

[0088] The catalyst was prepared using the same method as in Comparative Example 4, except that 1.56 g of nickel nitrate hexahydrate was replaced with 0.78 g of nickel nitrate hexahydrate and 0.78 g of cobalt nitrate hexahydrate. The specific preparation process is as follows:

[0089] The pseudoboehmite was dried in a dynamic oven at 120℃ for 12 hours, then removed and cooled to room temperature. It was then placed in a high-temperature muffle furnace and heated to 1200℃ at a heating rate of 2℃ / min and held for 8 hours. After natural cooling, it was removed to obtain the α-Al2O3 support.

[0090] 10g of α-Al₂O₃ support was placed in a rotating drum at the rear end of the pyrolysis reactor and rotated at a high speed of 1000 r / min. 0.78g of nickel nitrate hexahydrate and 0.78g of cobalt nitrate hexahydrate (Ni / Co molar ratio 1:1) were dissolved in 50mL of water and stirred until a homogeneous solution was formed. This solution was then placed in an atomizing solution storage tank. The flow rate of the carrier gas He was controlled at 100mL / min to carry the solution to the atomizer to form an aerosol. The aerosol was then carried into a pre-drying zone at 200℃ for drying. The dried aerosol was then carried into a high-temperature methane-oxygen torch in the tubular pyrolysis reaction zone via a carrier gas line. It was sprayed out at the nozzle and rapidly cooled by N₂ cooling gas, then brought into full contact with the support in the high-speed rotating drum for 30 minutes to achieve uniform loading. After natural cooling, the catalyst was obtained.

[0091] Catalyst performance evaluation:

[0092] 1g of catalyst from each example and comparative example was weighed and charged into a 20mL fixed-bed reactor. The reactor was subjected to a pure hydrogen atmosphere, a pressure of 2.0MPa, and a sterilization time of 5000h. -1Under these conditions, the temperature was increased to 350℃ at a heating rate of 30℃ / h and held for 6 hours. Then, it was heated to a pressure of 2.0 MPa for 5000 hours. -1 、 The catalytic performance of C2 fraction was tested on simulated refinery gas (gas composition: 0.7% acetylene, 3.5% hydrogen, 15% ethylene, and nitrogen as balance gas) under reaction conditions of 250℃.

[0093] The catalytic performance test results are shown in Table 1.

[0094] Table 1 Catalyst properties and catalytic performance data for the examples and comparative examples.

[0095]

[0096] 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 has been recycled 5 times.

[0097] In the various embodiments and comparative examples of the present invention, the methods for testing the apparent activation energy of the catalyst are as follows:

[0098] Under reaction conditions of 210–250 °C, the conversion frequency (TOF) of the selective hydrogenation reaction of acetylene was obtained at four temperature points by controlling the conversion rate to be less than 10%. A plot of ln(TOF) against 1000 / T (T being the reaction temperature, K) was obtained, and the reciprocal of the slope of the linear function was taken as the apparent activation energy of the catalyst (kJ / mol). Specific results are shown in Table 2.

[0099] The results of the chemisorption of the catalyst by C2H4-TPD are also shown in Table 2.

[0100] Table 2. Test results of C2H4-TPD chemisorption and apparent activation energy of the catalysts in the examples and comparative examples.

[0101]

[0102] Note: The temperature-programmed desorption amount of ethylene in Comparative Example 4 in Table 2 is recorded as 1.0.

[0103] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A supported C2 selective hydrogenation catalyst, comprising a support and an active component, wherein the active component is a Ni-Fe species and the nanoparticle size of the active component is (x±y) nm, wherein x=2~5 and y<0.20x.

2. The catalyst according to claim 1, characterized in that, The molar ratio of Ni to Fe in the catalyst is 0.25 to 6:1; And / or, in the catalyst, the active component, based on the mass of the catalyst, has a mass content of 0.1 to 10 wt% as a metallic element; And / or, in the catalyst, the mass content of the support is 90 to 99.9 wt%, based on the mass of the catalyst.

3. The catalyst according to claim 1, characterized in that, In the catalyst, the support is selected from at least one of α-Al2O3, SiO2, ZrO2, TiO2, CeO2, activated carbon, and molecular sieve, preferably α-Al2O3.

4. The catalyst according to claim 1, characterized in that, Based on the C2H4-TPD peak area of ​​Ni / α-Al2O3, the relative peak area ratio of the catalyst for C2H4-TPD is 0.8 to 1.0, preferably 0.79 to 0.91; And / or, the apparent activation energy of the catalyst is 37.0–45.0 kJ / mol, preferably 37.9–42.0 kJ / mol.

5. A method for preparing the catalyst according to any one of claims 1-4, comprising: The metal precursor solution is prepared by mixing a metal precursor salt and a solvent, which is then vaporized to form an aerosol. After drying and pyrolysis, the aerosol is sprayed onto the surface of a support to obtain the catalyst precursor. The metal precursor comprises a first metal component and a second metal component, wherein the first metal component is Ni and the second metal component is Fe.

6. The preparation method according to claim 5, characterized in that, The solvent includes at least one of water, an alcohol component, and a benzene component, preferably an alcohol component and / or a benzene component; wherein the alcohol component includes at least one of methanol, ethanol, propanol, isopropanol, butanol, and octanol; and the benzene component includes at least one of benzene, toluene, p-xylene, o-xylene, and m-xylene.

7. The preparation method according to claim 5, characterized in that, The specific process of vaporization to form aerosol is as follows: a carrier gas is used to carry the metal precursor solution to an atomizer for atomization to form aerosol; And / or, the carrier gas is at least one of air, He, Ar, and N2; the carrier gas flow rate is 10-200 mL / min; the atomization process can disperse the metal precursor solution into uniform droplets to form an aerosol.

8. The preparation method according to claim 5, characterized in that, The drying temperature is 100-250℃, preferably 150-200℃, and the time is 4h-24h, preferably 8h-12h; And / or, the pyrolysis treatment specifically involves: passing the dried aerosol into a combustible gas flame for pyrolysis.

9. The preparation method according to claim 5, characterized in that, During the injection process, cooling gas is used to cool the gas flow from the nozzle, and the cooled gas flow is then sprayed onto the surface of the carrier to obtain the metal catalyst. And / or, the catalyst support rotates at high speed in a high-speed rotating drum, which facilitates the uniform spraying of the cooled airflow onto the support surface.

10. The preparation method according to claim 8, characterized in that, The combustible gas includes at least one of methane, ethane, ethylene, and acetylene; And / or, the combustible gas may also include an oxidizing agent, preferably air or oxygen.

11. The preparation method according to claim 9, characterized in that, The cooled airflow is in contact with the carrier surface for 10 to 60 minutes; And / or, the cooling gas includes any one of air, N2, He, and Ar.

12. The application of the catalyst according to any one of claims 1-4 and the catalyst prepared by any one of claims 5-11 in the selective hydrogenation reaction of C2.

13. The application according to claim 12, characterized in that, The selective hydrogenation reaction of C2 involves contacting the raw materials acetylene and hydrogen with a catalyst to carry out a selective hydrogenation reaction, yielding the product ethylene.

14. The application according to claim 12, characterized in that, The reaction conditions for the selective hydrogenation reaction of C2 include: a reaction temperature of 210–250 °C, a reaction pressure of 1.5–2.0 MPa, and a volume hourly space velocity of 2000–5000 h⁻¹. -1 .

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