An active alumina-supported nickel-based bimetallic heterogeneous catalyst, a preparation method and application thereof

Abstract

The application provides an active alumina-supported nickel-based bimetallic heterogeneous catalyst and a preparation method and application thereof, and relates to the technical field of catalysts.The active alumina-supported nickel-based bimetallic heterogeneous catalyst provided by the application comprises active alumina and a nano-alloy supported on the active alumina, the nano-alloy comprises a first active metal and a second active metal, the first active metal is Ni, and the second active metal is Mo, Zn, Fe, Co, Cu, In, Sn, Y, Zr, V, W, Ga or Sc.The application uses active alumina as a carrier, uses nickel as a main active component, combines a second active transition metal to form an active nickel-based non-noble metal alloy, and uniformly distributes the alloy on the surface of the pores of the active alumina, so that the alloy structure and the surface of the carrier form a strong interaction, and the active center is more stable.The active alumina-supported nickel-based bimetallic heterogeneous catalyst provided by the application is cheap and environment-friendly, is used for preparing ethylene through catalytic dehydrogenation of ethane, has high ethane conversion rate, good ethylene selectivity and good reaction stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to an active alumina-supported nickel-based bimetallic heterogeneous catalyst, its preparation method, and its application. Background Technology

[0002] Low-carbon olefins, a cornerstone of modern industry, have long been primarily produced through naphtha cracking. This process involves high reaction temperatures, high energy consumption, and complex products. Ethylene production via catalytic dehydrogenation of ethane requires relatively lower reaction temperatures, exhibits high selectivity for ethylene as a product, and benefits from the wide availability of ethane, particularly the shale gas revolution which has brought abundant inexpensive low-carbon alkanes. Therefore, catalytic dehydrogenation of ethane is gradually becoming an attractive industrial strategy for olefin production.

[0003] The mainstream catalysts for this strategy currently include precious metal catalytic systems represented by platinum and heavy metal catalyst systems represented by chromium, which are highly toxic. Platinum-based catalysts are expensive and prone to carbon deposition and deactivation; chromium-based catalysts are highly biotoxic and do not meet the requirements of today's green development era. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an activated alumina-supported nickel-based bimetallic heterogeneous catalyst, its preparation method, and its application. The catalyst provided by this invention is inexpensive and environmentally friendly, and is used for the catalytic dehydrogenation of ethane to ethylene, exhibiting high ethane conversion, good ethylene selectivity, and good reaction stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides an activated alumina-supported nickel-based bimetallic multiphase catalyst, comprising activated alumina and a nano-alloy supported on the activated alumina. The nano-alloy comprises a first active metal and a second active metal, wherein the first active metal is Ni and the second active metal is Mo, Zn, Fe, Co, Cu, In, Sn, Y, Zr, V, W, Ga, or Sc.

[0007] Preferably, the loading of the first active metal in the catalyst is 0.2 to 5 wt%, and the molar ratio of the first active metal to the second active metal is 1:(0.1 to 10).

[0008] This invention provides a method for preparing the activated alumina-supported nickel-based bimetallic heterogeneous catalyst described above, comprising the following steps:

[0009] A precursor solution is obtained by mixing a soluble salt of the first active metal, a soluble salt of the second active metal, and water.

[0010] The activated alumina was impregnated in the precursor solution, and the impregnated activated alumina was subsequently dried, calcined, and reduced to obtain the activated alumina-supported nickel-based bimetallic multiphase catalyst.

[0011] Preferably, the impregnation is an equal-volume impregnation.

[0012] Preferably, the drying temperature is 80–120°C and the drying time is 8–12 hours.

[0013] Preferably, the calcination temperature is 500–900°C and the time is 3 hours, and the calcination is carried out in an air atmosphere.

[0014] Preferably, the reduction is a hydrogen reduction, which is carried out in a mixture of H2 and Ar, wherein the volume concentration of H2 in the mixture is 5-20%; the reduction temperature is 600°C and the time is 0.5-2 hours.

[0015] This invention provides the application of the activated alumina-supported nickel-based bimetallic heterogeneous catalyst described in the above technical solutions or the activated alumina-supported nickel-based bimetallic heterogeneous catalyst prepared by the above technical solutions in the catalytic dehydrogenation of ethane to ethylene.

[0016] Preferably, the feed gas for the reaction comprises H2, C2H6, and Ar, wherein the volume ratio of H2, C2H6, and Ar is (0–4.0):(2.0–5.0):18.0, and the feed space velocity of the feed gas is 600–6000 mL·g. -1 ·h -1 .

[0017] Preferably, the reaction temperature is 500–700°C.

[0018] This invention provides an activated alumina-supported nickel-based bimetallic multiphase catalyst, comprising activated alumina and a nano-alloy supported on the activated alumina. The nano-alloy includes a first active metal and a second active metal, wherein the first active metal is Ni, and the second active metal is Mo, Zn, Fe, Co, Cu, In, Sn, Y, Zr, V, W, Ga, or Sc. This invention uses activated alumina as a carrier, which has a porous structure and a large specific surface area; this invention uses nickel as the main active component, combined with a second active transition metal to form an active nickel-based non-noble metal alloy (Ni). x M yThe nickel-based bimetallic heterogeneous catalyst, uniformly distributed on the surface of the activated alumina channels, forms a strong interaction between the alloy structure and the support surface, making its active centers more stable. Within the alloy structure, the electronic state density of Ni and the second active metal changes, thereby altering the adsorption state of ethane at the active sites and pre-activating it after adsorption, thus improving catalytic performance. The activated alumina-supported nickel-based bimetallic heterogeneous catalyst provided by this invention is inexpensive and environmentally friendly, and is used for the catalytic dehydrogenation of ethane to ethylene, exhibiting high ethane conversion, good ethylene selectivity, and good reaction stability. Attached Figure Description

[0019] Figure 1 The images show the XRD patterns of the catalysts obtained in Examples 1-7 and Comparative Examples 1-2. Figure 1 (a) is the XRD pattern of the catalysts obtained in Examples 1, 3 and 5; (b) is the XRD pattern of the catalysts obtained in Examples 1, 2 and 7; (c) is the XRD pattern of the catalysts obtained in Examples 1, 4 and 6; and (d) is the XRD pattern of the catalysts obtained in Examples 1, Comparative Example 1 and Comparative Example 2.

[0020] Figure 2 This is a TEM image of the catalyst obtained in Example 1. Figure 2 (a) is a TEM image, and (b) is a magnified view of a portion of the TEM image.

[0021] Figure 3 These are HAADF-STEM and EDS images of the catalyst obtained in Example 1. Figure 3 (a) is a HAADF-STEM image, (b) to (d) are area scan images, (e) is a line scan image, and (f) is a point analysis image;

[0022] Figure 4 The graph shows the reusability of the catalyst obtained in Example 1. Detailed Implementation

[0023] This invention provides an activated alumina-supported nickel-based bimetallic multiphase catalyst, comprising activated alumina and a nano-alloy supported on the activated alumina. The nano-alloy comprises a first active metal and a second active metal, wherein the first active metal is Ni and the second active metal is Mo, Zn, Fe, Co, Cu, In, Sn, Y, Zr, V, W, Ga, or Sc.

[0024] In this invention, the loading of the first active metal in the catalyst is preferably 0.2–5 wt% (i.e., the mass of the first active metal is 0.2–5 wt% of the mass of the active alumina), more preferably 0.5–1 wt%, and the molar ratio of the first active metal to the second active metal is preferably 1:(0.1–10), more preferably 1:(0.25–3), and even more preferably 1:(0.33–1). In this invention, the particle size of the nano-alloy is preferably 3–5 nm.

[0025] In this invention, the activated alumina serves as a porous carrier, possessing advantages such as low cost, high thermal stability, large specific surface area, and easily adjustable interaction forces with the active components. This invention uses a nickel-based non-precious metal alloy as the active component, uniformly distributed on the surface of the activated alumina channels, resulting in a strong interaction between the alloy structure and the carrier surface.

[0026] This invention provides a method for preparing the activated alumina-supported nickel-based bimetallic heterogeneous catalyst described above, comprising the following steps:

[0027] A precursor solution is obtained by mixing a soluble salt of the first active metal, a soluble salt of the second active metal, and water.

[0028] The activated alumina was impregnated in the precursor solution, and the impregnated activated alumina was subsequently dried, calcined, and reduced to obtain the activated alumina-supported nickel-based bimetallic multiphase catalyst.

[0029] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known in the art.

[0030] The present invention mixes a soluble salt of a first active metal, a soluble salt of a second active metal, and water to obtain a precursor solution.

[0031] In this invention, the soluble salt of the first active metal is preferably nickel nitrate, and the soluble salt of the second active metal is a molybdenum salt, zinc salt, iron salt, cobalt salt, copper salt, indium salt, tin salt, yttrium salt, zirconium salt, vanadium salt, tungsten salt, gallium salt, or scandium salt. The zinc salt, iron salt, indium salt, cobalt salt, copper salt, gallium salt, yttrium salt, and zirconium salt are each preferably their corresponding nitrates. The molybdenum salt is preferably ammonium molybdate tetrahydrate, the tungsten salt is preferably ammonium tungstate, the tin salt is preferably stannous chloride, the vanadium salt is preferably ammonium metavanadate, vanadium oxysulfate, or vanadium oxalate, and the scandium salt is preferably scandium trifluoromethanesulfonate.

[0032] In this invention, the molar ratio of the first active metal ion to the second active metal ion in the precursor solution is preferably 1:(0.1-10), and the concentration of the first active metal ion in the precursor solution is preferably 2-50 mg / mL.

[0033] After obtaining the precursor solution, the present invention impregnates activated alumina in the precursor solution.

[0034] In this invention, the activated alumina is preferably commercially available γ-Al2O3. The activated alumina is thoroughly dried, and its saturated water absorption rate is measured for later use.

[0035] In this invention, the impregnation is preferably an equal-volume impregnation. The impregnation temperature is preferably 10–120°C, and in this embodiment, the impregnation is preferably carried out at room temperature. The total impregnation time is preferably 6–12 hours, and during the impregnation process, stirring is preferably performed every 30 minutes.

[0036] After impregnation, the present invention sequentially dries, calcines, and reduces the impregnated activated alumina to obtain the activated alumina-supported nickel-based bimetallic multiphase catalyst.

[0037] In this invention, the drying temperature is preferably 80–120°C, more preferably 100°C, and the drying time is preferably 8–12 hours. In this embodiment, the drying is preferably carried out in an oven. In this invention, the calcination temperature is preferably 500–900°C, more preferably 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C, and the calcination time is preferably 3 hours. The calcination is preferably carried out in an air atmosphere. In this embodiment, the calcination is preferably carried out in a muffle furnace. During the calcination process, the soluble metal salt decomposes in the air to form a mixed oxide, which reacts with the hydroxyl groups on the surface of the activated alumina and anchors to the surface of the support. By adjusting the calcination temperature, the dispersion of the bimetallic nanoparticles and the binding strength with the support can be adjusted. The higher the temperature, the stronger the binding between the mixed metal oxide and the support, and the more dispersed and difficult to reduce it, thereby controlling the catalytic performance.

[0038] In this invention, the reduction is preferably hydrogen reduction, which is preferably carried out in a mixture of H2 and Ar, wherein the volume concentration of H2 in the mixture is preferably 5-20%, more preferably 10-15%; the reduction temperature is preferably 600°C, and the reduction time is preferably 0.5-2 hours. Preferably, the calcined sample is loaded into a fixed-bed reaction tube, the mixed gas is introduced, and reduction is carried out at 600°C.

[0039] The preparation method provided by this invention is simple and easy to scale up for production.

[0040] This invention provides the application of the activated alumina-supported nickel-based bimetallic heterogeneous catalyst described in the above technical solutions or the activated alumina-supported nickel-based bimetallic heterogeneous catalyst prepared by the above technical solutions in the catalytic dehydrogenation of ethane to ethylene.

[0041] In this invention, the feed gas for the reaction preferably comprises H2, C2H6, and Ar, and the volume ratio of H2, C2H6, and Ar is preferably (0–4.0):(2.0–5.0):18.0, more preferably (2.0–3.0):(3.0–5.0):18.0, and even more preferably 2.0:5.0:18.0. Adding H2 to the feed gas in this invention can slow down carbon deposition; although it slightly reduces the conversion rate, it can significantly improve stability. In this invention, the feed space velocity (WHSV) of the feed gas is preferably 600–6000 mL·g. -1 ·h -1 More preferably, it is 3000–5000 mL·g -1 ·h -1 In this invention, the reaction temperature is preferably 500–700°C, more preferably 600°C.

[0042] The active alumina-supported nickel-based bimetallic heterogeneous catalyst provided by this invention exhibits excellent catalytic activity and selectivity for the catalytic dehydrogenation of ethane to ethylene, achieving a high yield of ethylene. The catalyst provided by this invention possesses advantages such as good catalytic performance, high stability, good selectivity, low cost, strong practicality, and reusability, offering a new industrially viable, non-precious metal, environmentally friendly catalytic system for the catalytic dehydrogenation of ethane to ethylene.

[0043] To further illustrate the present invention, the following detailed description, in conjunction with examples, of the active alumina-supported nickel-based bimetallic heterogeneous catalyst, its preparation method, and its application, is provided but should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] 96.2 mg of nickel nitrate hexahydrate and 19.5 mg of ammonium molybdate tetrahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand (at room temperature). The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100 °C oven to dry for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours with a 10% (volume concentration) H₂ / Ar mixed gas to obtain the Ni₃Mo / Al₂O₃ catalyst, denoted as C-1.

[0046] Example 2

[0047] 96.2 mg of nickel nitrate hexahydrate and 32.9 mg of zinc nitrate hexahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 500℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Zn / Al₂O₃ catalyst, denoted as C-2.

[0048] Example 3

[0049] 96.2 mg of nickel nitrate hexahydrate and 43.2 mg of indium nitrate pentahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 550℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃In / Al₂O₃ catalyst, denoted as C-3.

[0050] Example 4

[0051] 96.2 mg of nickel nitrate hexahydrate and 44.7 mg of ferric nitrate nonahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 600℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Fe / Al₂O₃ catalyst, denoted as C-4.

[0052] Example 5

[0053] 96.2 mg of nickel nitrate hexahydrate and 26.7 mg of copper nitrate trihydrate were dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was dried in an oven at 100 °C for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 650 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Cu / Al₂O₃ catalyst, denoted as C-5.

[0054] Example 6

[0055] 96.2 mg of nickel nitrate hexahydrate and 32.2 mg of cobalt nitrate hexahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 750℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Co / Al₂O₃ catalyst, denoted as C-6.

[0056] Example 7

[0057] 96.2 mg of nickel nitrate hexahydrate and 25.0 mg of stannous chloride dihydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes and then dried in an oven at 100 °C for 12 hours after 8 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 800 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Sn / Al₂O₃ catalyst, denoted as C-7.

[0058] Example 8

[0059] 96.2 mg of nickel nitrate hexahydrate and 47.3 mg of zirconium nitrate pentahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 850℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Zr / Al₂O₃ catalyst, denoted as C-8.

[0060] Example 9

[0061] 96.2 mg of nickel nitrate hexahydrate and 54.3 mg of scandium trifluoromethanesulfonate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 900℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Sc / Al₂O₃ catalyst, denoted as C-9.

[0062] Example 10

[0063] 96.2 mg of nickel nitrate hexahydrate and 29.2 mg of ammonium tungstate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand for 12 h. After standing, the mixture was dried in an oven at 120 °C for 12 h. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 h. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 h with a 10% H₂ / Ar mixed gas to obtain the Ni₃W / Al₂O₃ catalyst, denoted as C-10.

[0064] Example 11

[0065] 96.2 mg of nickel nitrate hexahydrate and 30.4 mg of yttrium nitrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand for 12 h. After standing, the mixture was dried in an oven at 120 °C for 12 h. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 h. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 h with a 10% H₂ / Ar mixed gas to obtain the Ni₃Y / Al₂O₃ catalyst, denoted as C-11.

[0066] Example 12

[0067] 96.2 mg of nickel nitrate hexahydrate and 28.3 mg of gallium nitrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was dried in an oven at 100 °C for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₃Ga / Al₂O₃ catalyst, denoted as C-12.

[0068] Example 13

[0069] 96.2 mg of nickel nitrate hexahydrate and 16.9 mg of vanadium oxysulfate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand for 12 h. After standing, the mixture was dried in an oven at 120 °C for 12 h. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 h. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 h with a 10% H₂ / Ar mixed gas to obtain the Ni₃V / Al₂O₃ catalyst, denoted as C-13.

[0070] Example 14

[0071] 105.5 mg of nickel nitrate hexahydrate and 16.0 mg of ammonium molybdate tetrahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes, and after 8 hours, it was placed in a 100℃ oven and dried for 12 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700℃ and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600℃ for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni₄Mo / Al₂O₃ catalyst, denoted as C-14.

[0072] Example 15

[0073] Weigh out 56.4 mg of nickel nitrate hexahydrate and 34.2 mg of ammonium molybdate tetrahydrate, dissolve them in 2 mL of water, then add 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃), stir well, let stand, stir once every 30 min, and after 8 h, place in a 100 °C oven to dry for 12 h. Place the dried sample in a porcelain boat, then place it in a muffle furnace at 700 °C and calcine under air for 3 h; after cooling, take 0.5 g of the sample and load it into a fixed-bed reaction tube, pass through a 10% H₂ / Ar mixed gas and reduce at 600 °C for 2 h to obtain the NiMo / Al₂O₃ catalyst, denoted as C-15.

[0074] Example 16

[0075] Weigh 25.2 mg of nickel nitrate hexahydrate and 45.8 mg of ammonium molybdate tetrahydrate and dissolve them in 2 mL of water. Then add 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃), stir well, and let stand. Stir once every 30 min. After 8 h, dry in an oven at 100 °C for 12 h. Place the dried sample in a porcelain boat and then place it in a muffle furnace at 700 °C and calcine in air for 3 h. After cooling, take 0.5 g of the sample and load it into a fixed-bed reaction tube. Reduce it at 600 °C for 2 h by passing a 10% H₂ / Ar mixed gas to obtain the NiMo₃ / Al₂O₃ catalyst, denoted as C-16.

[0076] Comparative Example 1

[0077] 96.2 mg of nickel nitrate hexahydrate was dissolved in 2 mL of water, and then 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added. After stirring evenly, the mixture was allowed to stand, stirred once every 30 minutes, and then dried in an oven at 100 °C for 12 hours after 8 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours with a 10% H₂ / Ar mixed gas to obtain the Ni / Al₂O₃ catalyst, denoted as C-17.

[0078] Comparative Example 2

[0079] 19.5 mg of ammonium molybdate tetrahydrate was dissolved in 2 mL of water, and then 2.0 g of fully dried activated alumina (commercial γ-Al₂O₃) was added. After stirring evenly, the mixture was allowed to stand, stirred once every 30 min, and then dried in an oven at 100 °C for 12 h after 8 h. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 700 °C and calcined in air for 3 h. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 h with a 10% H₂ / Ar mixed gas to obtain the Mo / Al₂O₃ catalyst, denoted as C-18.

[0080] Structural and performance characterization

[0081] The catalysts obtained in Examples 1-7 and Comparative Examples 1-2 were characterized by XRD, and the results are as follows: Figure 1 As shown, the XRD patterns of each sample only show the characteristic peaks of activated alumina, indicating that the active components are uniformly dispersed on the surface of the support and there are no obvious aggregated particles.

[0082] The catalyst obtained in Example 1 was characterized by TEM and EDS, and the results are as follows: Figure 2 and Figure 3 As shown, where Figure 2 This is a TEM image of the catalyst obtained in Example 1. Figure 2 (a) is a TEM image, and (b) is a magnified view of a portion of the TEM image. Figure 3 These are HAADF-STEM and EDS images of the catalyst obtained in Example 1. Figure 3 Image (a) is a HAADF-STEM image, (b)–(d) are area scan images, (e) is a line scan image, and (f) is a point analysis image. Figure 2 and Figure 3 It can be seen that Ni and Mo are uniformly distributed on the surface of the support, and a nano-alloy phase is formed. The nano-alloy particles are uniform in size, with a particle size of about 3 to 5 nm.

[0083] Application Example 1

[0084] The catalysts prepared in Examples 1-16 and Comparative Examples 1-2 were used in the catalytic dehydrogenation reaction of ethane to illustrate the catalytic performance of different catalysts in the catalytic reaction of ethane to ethylene.

[0085] A mixed reaction gas was introduced into the catalyst obtained by in-situ reduction in a fixed-bed reactor, containing H2: 2 mL / min, C2H6: 5 mL / min, and Ar: 18 mL / min. The system was maintained at a constant temperature of 600 °C for the reaction. The outlet of the fixed-bed reactor was connected to a Shimadzu GC-2014C gas chromatograph for product component analysis. The product composition was analyzed using the correction factor method to obtain the content of each component in the product and to calculate the conversion and selectivity. After 10 min of reaction, the ethane conversion and ethylene selectivity of different catalysts were measured as the initial data of the reaction, as shown in Table 1.

[0086] Table 1. Results of the catalysts prepared in Examples 1-16 and Comparative Examples 1-2 in the catalytic dehydrogenation of ethane to ethylene.

[0087]

[0088]

[0089] As can be seen from Table 1, the catalysts prepared in this invention have good catalytic activity and selectivity for the catalytic dehydrogenation of ethane to ethylene.

[0090] Example 17

[0091] Taking catalyst C-1 (Ni3Mo / Al2O3) as an example, the performance of this series of catalysts in the catalytic dehydrogenation reaction of ethane is explained.

[0092] Reaction conditions: 0.5 g of catalyst C-1 (Ni3Mo / Al2O3) was obtained by in-situ reduction in a fixed-bed reactor. A mixed reaction gas was introduced: H2: 2 mL / min, C2H6: 5 mL / min, Ar: 18 mL / min, and the system was maintained at a constant temperature of 600 °C for the reaction. The outlet of the fixed-bed reactor was connected to a Shimadzu GC-2014C gas chromatograph for product component analysis. The product composition was analyzed using the correction factor method to obtain the content of each component in the product and to calculate the conversion and selectivity. After 12 h of reaction, the product was cooled and removed. The catalyst was regenerated by burning off the carbon deposits in a muffle furnace under the preparation conditions. The catalyst was then reloaded into the fixed-bed reactor and reduced in situ again before the reaction was repeated. Reaction data for three reuses of the catalyst are shown in [the table below]. Figure 4 As shown.

[0093] from Figure 4 It can be seen that the catalyst prepared by the present invention can be reused, and in repeated use, it still has catalytic activity comparable to that when it was first used.

[0094] As can be seen from the above embodiments, the nickel-based bimetallic catalyst supported on the active alumina material prepared by the present invention has a good catalytic effect on the reaction of ethane catalytic dehydrogenation to ethylene.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of an activated alumina-supported nickel-based bimetallic heterogeneous catalyst in the catalytic dehydrogenation of ethane to ethylene; wherein the feed gas of the reaction is H2, C2H6 and Ar, and the volume ratio of H2, C2H6 and Ar is (0~4.0):(2.0~5.0):18.0; The preparation method of the activated alumina-supported nickel-based bimetallic heterogeneous catalyst is as follows: 96.2 mg of nickel nitrate hexahydrate and 47.3 mg of zirconium nitrate pentahydrate were weighed and dissolved in 2 mL of water. Then, 2.0 g of fully dried activated alumina was added, stirred evenly, and allowed to stand. The mixture was stirred once every 30 minutes and then dried in an oven at 100 °C for 12 hours after 8 hours. The dried sample was placed in a porcelain boat and then placed in a muffle furnace at 850 °C and calcined in air for 3 hours. After cooling, 0.5 g of the sample was placed in a fixed-bed reaction tube and reduced at 600 °C for 2 hours by passing a H2 / Ar mixed gas through it to obtain the catalyst. The volume concentration of H2 in the H2 / Ar mixed gas was 10%.

2. The application according to claim 1, characterized in that, The feed space velocity of the raw gas is 600~6000 mL·g. -1 ·h -1 .

3. The application according to claim 1 or 2, characterized in that, The reaction temperature is 500~700℃.

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