Heteronuclear FeCu diatomic catalyst as well as preparation method and application thereof

Abstract

The invention discloses a heteronuclear FeCu diatom catalyst and a preparation method and application thereof, the heteronuclear FeCu diatom catalyst comprises a carrier, the carrier is loaded with heteronuclear FeCu diatoms, the carrier is also loaded with an additive element, and the additive element is at least one of a potassium element, a sodium element and a lithium element. The preparation method comprises the following steps: dispersing a carrier precursor, an iron source and a copper source in a solvent for reaction, and centrifuging to obtain a solid product; and mixing the solid product with an additive containing additive elements, and calcining in an inert atmosphere to obtain the heteronuclear FeCu diatomic catalyst. The catalyst prepared by the invention has abundant metal anchoring sites and excellent structural stability, can realize high loading capacity and high dispersity of active metal, shows high ethanol selectivity and space time yield in CO2 hydrogenation reaction, and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of energy chemical engineering and catalysis technology, specifically relating to a heteronuclear FeCu diatomic catalyst, its preparation method and application. Background Technology

[0002] Carbon dioxide (CO2), a major greenhouse gas, is also an abundant and inexpensive C1 resource. Thermocatalytic hydrogenation, directly converting CO2 into high-value fuels and chemicals, is a crucial pathway to achieving the "carbon cycle." Among these, CO2 hydrogenation to ethanol technology has attracted particular attention. Ethanol is not only an important clean fuel additive that can directly replace or blend with gasoline, but it can also serve as a basic chemical feedstock, with huge market demand. Furthermore, its production process is highly compatible with existing energy infrastructure, possessing the potential for rapid industrialization.

[0003] However, the CO2 molecule is chemically stable with high C=O bond energy, posing a significant challenge to its activation and selective conversion. In the CO2 hydrogenation to ethanol reaction pathway, problems such as low target product selectivity and difficulty in C=O coupling are common, leading to the generation of numerous byproducts (such as methane, carbon monoxide, and light olefins), severely impacting the process's economics.

[0004] Therefore, developing high-performance catalysts that can efficiently catalyze the formation of C-C bonds and precisely direct ethanol has become a core challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a heteronuclear FeCu diatomic catalyst, its preparation method and application. This heteronuclear FeCu diatomic catalyst has abundant metal anchoring sites and excellent structural stability, and can achieve high loading and high dispersion of active metals. It exhibits high ethanol selectivity and space-time yield in CO2 hydrogenation reaction and has good application prospects.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A heteronuclear FeCu diatomic catalyst, comprising a support on which heteronuclear FeCu diatoms are loaded, and an additive element loaded on the support, wherein the additive element is at least one selected from potassium, sodium, and lithium.

[0008] In one or more embodiments of the present invention, in the carrier, the molar ratio of Fe to Cu elements in terms of atomic number is (4-12):(2-8).

[0009] In one or more embodiments of the present invention, in the carrier, the molar ratio of Fe element to added element in terms of atomic number is (4-12):(0.4-1.2).

[0010] In one or more embodiments of the present invention, the support is a nitrogen-doped porous carbon material.

[0011] Another specific embodiment of the present invention provides the following technical solution:

[0012] A method for preparing a heteronuclear FeCu diatomic catalyst, the method comprising the following steps:

[0013] The carrier precursor, iron source, and copper source were dispersed in a solvent and reacted. After centrifugation, a solid product was obtained.

[0014] The solid product was mixed with an additive containing the added elements and calcined under an inert atmosphere to obtain a heteronuclear FeCu diatomic catalyst.

[0015] In one or more embodiments of the present invention, the carrier precursor is at least one selected from melamine, urea, and dicyandiamide; and / or,

[0016] The iron source is at least one of ferric nitrate, ferric sulfate, and ferric chloride; and / or,

[0017] The copper source is at least one of copper nitrate, copper sulfate, and copper chloride; and / or,

[0018] The additive is at least one of potassium chloride, sodium chloride, and lithium chloride.

[0019] In one or more embodiments of the present invention, the amount of the carrier precursor is 5g-10g; and / or,

[0020] The amount of iron source used is 4 mmol-12 mmol; and / or,

[0021] The amount of copper source used is 2 mmol-8 mmol; and / or,

[0022] The amount of the additive is 0.4 mmol to 1.2 mmol.

[0023] In one or more embodiments of the present invention, the carrier precursor, iron source, and copper source are dispersed in a solvent and reacted with stirring at 40°C-120°C for 2-4 hours; after centrifugation, they are dried at 80°C-120°C for 8-12 hours; and / or,

[0024] The calcination temperature is 400℃-650℃, and the time is 4h-8h; and / or,

[0025] After the calcination step is completed, the obtained product is cooled, and then ground, extruded and crushed. The particle size of the crushed product is 40-60 mesh, thus obtaining a heteronuclear FeCu diatomic catalyst.

[0026] Another specific embodiment of the present invention provides the following technical solution:

[0027] Application of a heteronuclear FeCu diatomic catalyst in the hydrogenation of CO2 to ethanol.

[0028] In one or more embodiments of the present invention, a heteronuclear FeCu diatomic catalyst is mixed with 40-60 mesh quartz sand at a mass ratio of 1:(1-5) and then packed into a reaction tube. The mixture is reduced at 300℃-600℃ for 2-8 hours under a hydrogen atmosphere. After reduction, the reaction is carried out using a reaction gas at a temperature of 280℃-380℃, a pressure of 2MPa-6MPa, and a space velocity of 3000 mL·g. cat -1 ·h -1 -12000mL·g cat -1 ·h -1 .

[0029] Compared with existing technologies, this invention dops Fe and Cu into nitrogen-doped porous carbon materials and then modifies them with specific additives (potassium chloride, sodium chloride, and lithium chloride). The resulting heteronuclear FeCu diatomic catalyst exhibits excellent stability and activity, with abundant metal anchoring sites and excellent structural stability. It can achieve high loading and high dispersion of active metals and shows high ethanol selectivity and space-time yield in CO2 hydrogenation reaction, demonstrating promising application prospects. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Aberration-corrected electron microscopy of the 4Fe4Cu / CN-0.4K catalyst in Example 1 of this invention. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0033] Heteronuclear Fe-based diatomic catalysts (such as Fe-M, where M is a metal like Cu, Zn, or Co) exhibit significant advantages in the hydrogenation of CO2 to ethanol. These catalysts achieve precise adsorption and directional transformation of reaction intermediates by constructing a synergistic catalytic interface on atomically dispersed heteronuclear bimetallic sites (e.g., Fe-Cu). Their unique advantage lies in the synergistic effect of the two sites and electronic regulation. Developing highly efficient heteronuclear Fe-based diatomic catalysts is not only a key technological breakthrough for achieving highly selective CO2-to-ethanol production, but also provides a means to understand the C-C coupling mechanism at the atomic scale.

[0034] This invention provides a heteronuclear FeCu diatomic catalyst, which is prepared by doping Fe and Cu into nitrogen-doped porous carbon material and then modifying it with specific additives (potassium chloride, sodium chloride, and lithium chloride). The heteronuclear FeCu diatomic catalyst provided in this application facilitates the formation and stability of the Fe5C2 active phase during the carbon dioxide hydrogenation reaction and is beneficial to the formation of the *CH2+ surface on Fe5C2. x The stability of the CO bond in the O intermediate increases the stability and activity of the catalyst, promotes carbon chain growth, avoids excessive hydrogenation, and thus facilitates the formation of ethanol and reduces the selectivity of byproducts such as alkanes and CO.

[0035] One specific embodiment of the present invention provides a heteronuclear FeCu diatomic catalyst, which includes a support on which heteronuclear FeCu diatomic atoms are loaded, and an additive element is also loaded on the support, wherein the additive element is at least one selected from potassium, sodium and lithium.

[0036] Furthermore, the molar ratio of Fe to Cu, in terms of atomic number, is (4-12):(2-8), and the molar ratio of Fe to the added elements, in terms of atomic number, is (4-12):(0.4-1.2). By controlling the proportions of each element, the stability and activity of the catalyst are optimized.

[0037] Furthermore, the carrier is a nitrogen-doped porous carbon material.

[0038] Another specific embodiment of the present invention provides a method for preparing a heteronuclear FeCu diatomic catalyst, which specifically includes the following steps:

[0039] Step 1: Disperse the carrier precursor, iron source and copper source in a solvent and react them. Centrifuge to obtain a solid product.

[0040] Specifically, the carrier precursor is at least one of melamine, urea, and dicyandiamide, used in an amount of 5g-10g. The iron source is at least one of ferric nitrate, ferric sulfate, and ferric chloride, used in an amount of 4mmol-12mmol. The copper source is at least one of copper nitrate, copper sulfate, and copper chloride, used in an amount of 2mmol-8mmol.

[0041] The carrier precursor was dispersed in a round-bottom flask containing a methanol solution. After uniform dispersion, an iron source and a copper source were added sequentially, and the mixture was stirred until completely dissolved and reacted. The stirring temperature was 40℃-120℃, and the stirring time was 2-4 hours. After cooling to room temperature, the solid product was collected by centrifugation and dried at 80℃-120℃ for 8-12 hours.

[0042] Step 2: Grind and mix the solid product and the additive containing the added elements, and calcine under an inert atmosphere to obtain a heteronuclear FeCu diatomic catalyst.

[0043] Specifically, the additive is at least one of potassium chloride, sodium chloride, and lithium chloride, in an amount of 0.4 mmol to 1.2 mmol. The inert atmosphere is argon, the calcination temperature is 400℃ to 650℃, the time is 4h to 8h, after calcination, the product is cooled, then ground, extruded and crushed, and the particle size of the crushed product is 40 mesh to 60 mesh.

[0044] Another specific embodiment of the present invention provides the application of heteronuclear FeCu diatomic catalysts in the hydrogenation of CO2 to ethanol.

[0045] Specifically, a heteronuclear FeCu diatomic catalyst was mixed with 40-60 mesh quartz sand at a mass ratio of 1:(1-5) and packed into a reaction tube. Reduction was carried out at 300℃-600℃ for 2-8 hours under a hydrogen atmosphere. After reduction, the reaction gas was switched to (24% CO2, 72% H2, 4% Ar) for further reaction at a temperature of 280℃-380℃, a pressure of 2MPa-6MPa, and a space velocity of 3000 mL·g. cat -1 ·h -1 -12000mL·g cat -1 ·h -1 .

[0046] The present invention will be further described in detail below with reference to specific embodiments.

[0047] Example 1

[0048] The heteronuclear FeCu diatomic catalyst in this embodiment is a 4Fe4Cu / CN-0.4K catalyst, and its specific preparation is as follows:

[0049] (1) Disperse 5 g of melamine in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 4 mmol of ferric nitrate and 4 mmol of copper nitrate in sequence. After complete dissolution, place the flask in an oil bath and stir at a constant temperature of 120 °C for 2 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 120 °C for 8 h.

[0050] (2) After drying, grind it into powder, then add 0.4 mmol of potassium chloride and grind it together. Then put it into a tube furnace and calcine it at 550 °C for 5 h under an argon atmosphere to obtain 4Fe4Cu / CN-0.4K catalyst.

[0051] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0052] In this embodiment, the spherical aberration electron microscope (SEM) of the 4Fe4Cu / CN-0.4K catalyst is as follows: Figure 1 As shown in the figure, the red markings represent heteronuclear FeCu diatoms.

[0053] Example 2

[0054] The heteronuclear FeCu diatomic catalyst in this embodiment is a 6Fe2Cu / CN-0.8Na catalyst, and its specific preparation is as follows:

[0055] (1) Disperse 8 g of dicyandiamide in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 6 mmol of ferric sulfate and 2 mmol of copper sulfate in sequence. After complete dissolution, place the flask in an oil bath and stir at 60 °C for 3 h. After cooling to room temperature, centrifuge to collect the solid product and dry it in an oven at 100 °C for 10 h.

[0056] (2) After drying, grind it into powder, then add 0.8 mmol of sodium chloride and grind it together. Then put it into a tube furnace and calcine it at 500 °C for 6 h under an argon atmosphere to obtain 6Fe2Cu / CN-0.8Na catalyst.

[0057] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0058] Example 3

[0059] In this embodiment, the heteronuclear FeCu diatomic catalyst is a 12Fe8Cu / CN-1Li catalyst, and its specific preparation is as follows:

[0060] (1) Disperse 10 g of urea in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 12 mmol of ferric chloride and 8 mmol of copper chloride in sequence. After complete dissolution, place the flask in an oil bath and stir at a constant temperature of 40 °C for 4 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 80 °C for 12 h.

[0061] (2) After drying, grind it into powder, then add 1 mmol of lithium chloride and grind it together. Then put it into a tube furnace and calcine it at 400 °C for 8 h under an argon atmosphere to obtain 12Fe8Cu / CN-1.0Li catalyst.

[0062] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0063] Example 4

[0064] The heteronuclear FeCu diatomic catalyst in this embodiment is an 8Fe6Cu / CN-1.2Na catalyst, and its specific preparation is as follows:

[0065] (1) Disperse 6 g of melamine in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 8 mmol of ferric sulfate and 6 mmol of copper nitrate in sequence. After complete dissolution, place the flask in an oil bath and stir at 80 °C for 4 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 80 °C for 12 h.

[0066] (2) After drying, grind it into powder, then add 1.2 mmol of sodium chloride and grind it together. Then put it into a tube furnace and calcine it at 650 °C for 4 h under an argon atmosphere to obtain 8Fe6Cu / CN-1.2Na catalyst.

[0067] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0068] Example 5

[0069] In this embodiment, the heteronuclear FeCu diatomic catalyst is a 10Fe6Cu / CN-1Li catalyst, and its specific preparation is as follows:

[0070] (1) Disperse 9 g of urea in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 10 mmol of ferric chloride and 6 mmol of copper sulfate in sequence. After complete dissolution, place the flask in an oil bath and stir at 100 °C for 3 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 100 °C for 10 h.

[0071] (2) After drying, grind it into powder, then add 1 mmol of lithium chloride and grind it together. Then put it into a tube furnace and calcine it at 600 °C for 7 h under an argon atmosphere to obtain 10Fe6Cu / CN-1.0Li catalyst.

[0072] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0073] Example 6

[0074] The heteronuclear FeCu diatomic catalyst in this embodiment is a 4Fe8Cu / CN-0.6K catalyst, and its specific preparation is as follows:

[0075] (1) Disperse 7 g of dicyandiamide in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 4 mmol of ferric nitrate and 8 mmol of copper chloride in sequence. After complete dissolution, place the flask in an oil bath and stir at 80 °C for 2 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 120 °C for 8 h.

[0076] (2) After drying, grind it into powder, then add 0.6 mmol of potassium chloride and grind it together. Then put it into a tube furnace and calcine it at 450 °C for 8 h under an argon atmosphere to obtain 4Fe8Cu / CN-0.6K catalyst.

[0077] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0078] Example 7

[0079] In this embodiment, the heteronuclear FeCu diatomic catalyst is a 4Fe4Cu / CN-2K catalyst, and its specific preparation is as follows:

[0080] (1) Disperse 5 g of melamine in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 4 mmol of ferric nitrate and 4 mmol of copper nitrate in sequence. After complete dissolution, place the flask in an oil bath and stir at a constant temperature of 120 °C for 2 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 120 °C for 8 h.

[0081] (2) After drying, grind it into powder, then add 2 mmol of potassium chloride and grind it together. Then put it into a tube furnace and calcine it at 550 °C for 5 h under an argon atmosphere to obtain 4Fe4Cu / CN-2K catalyst.

[0082] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0083] Comparative Example 1

[0084] The heteronuclear FeCu diatomic catalyst in this comparative example is a 4Fe4Cu / CN catalyst, and its specific preparation is as follows:

[0085] (1) Disperse 5 g of melamine in a round-bottom flask containing 50 mL of methanol solution. After the dispersion is uniform, add 4 mmol of ferric nitrate and 4 mmol of copper nitrate in sequence. After complete dissolution, place the flask in an oil bath and stir at a constant temperature of 120 °C for 2 h. After cooling to room temperature, collect the solid product by centrifugation and dry it in an oven at 120 °C for 8 h.

[0086] (2) After drying, it is ground into powder and then placed in a tube furnace and calcined at 550 °C for 5 h under an argon atmosphere to obtain 4Fe4Cu / CN catalyst.

[0087] (3) Granulate the calcined catalyst to a particle size of 40-60 mesh.

[0088] Application Example 1

[0089] Weigh 0.5 g of the catalyst from Example 1. The mass ratio of quartz sand to catalyst is 3:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 400 °C for 2 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (320 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 6000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (4 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0090] Application Example 2

[0091] Weigh 0.5 g of the catalyst from Example 2. The mass ratio of quartz sand to catalyst is 1:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 300 °C for 8 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (280 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) at a space velocity of 3000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (6 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0092] Application Example 3

[0093] Weigh 0.5 g of the catalyst from Example 3. The mass ratio of quartz sand to catalyst is 2:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 300 °C for 2 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (300 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 12000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (2 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0094] Application Example 4

[0095] Weigh 0.5 g of the catalyst from Example 4. The mass ratio of quartz sand to catalyst is 5:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 600 °C for 6 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (380 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 9000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (3 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0096] Application Example 5

[0097] Weigh 0.5 g of the catalyst from Example 5. The mass ratio of quartz sand to catalyst is 4:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 500 °C for 6 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (320 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 6000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (5 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0098] Application Example 6

[0099] Weigh 0.5 g of the catalyst from Example 6. The mass ratio of quartz sand to catalyst is 3:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 400 °C for 4 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (360 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 3000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (2 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0100] Application Example 7

[0101] Weigh 0.5 g of the catalyst from Example 7. The mass ratio of quartz sand to catalyst is 3:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce at 400 °C for 2 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (320 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) with a space velocity of 6000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (4 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0102] Application Example 8

[0103] Weigh 0.5 g of the catalyst from Comparative Example 1. The mass ratio of quartz sand to catalyst is 3:1. Mix them thoroughly. First, fill a fixed-bed reaction tube (inner diameter 6 mm) with a certain amount of quartz wool. Then, fill the tube with the mixture of quartz sand and catalyst. Seal the top of the catalyst with a certain amount of quartz wool to prevent gas backmixing from carrying the catalyst away. Reduce the catalyst at 400 °C for 2 h under a hydrogen atmosphere. After the reduction is complete, wait for the temperature to drop to the reaction temperature (320 °C). Then, switch the gas to the reaction gas (24% CO2, 72% H2, 4% Ar) at a space velocity of 6000 mL·g. cat -1 ·h -1 The pressure was increased to the target pressure (4 MPa) under the action of the back pressure valve to start the reaction. The reaction time was 45 h. The gas phase tail gas was detected online every 2 h using a gas chromatograph equipped with FID and TCD detectors. N2 was used as an internal standard for correction to obtain the contents of hydrocarbons, CO, H2, CO2 and N2. After the reaction was completed, the peak area of ​​the aqueous phase and oil phase was measured by offline gas chromatography to obtain the molar amount of each component.

[0104] Table 1. Experimental Results of Application Examples

[0105]

[0106] As shown in Table 1, the heteronuclear FeCu diatomic catalysts prepared in this invention exhibit high catalytic activity in the catalytic hydrogenation of CO2 to ethanol. Comparing the above examples reveals that differences in the type of metal precursor, additives, catalyst preparation process, and operating conditions during the reaction all lead to variations in catalyst activity. Among them, the heteronuclear FeCu diatomic catalyst 4Fe4Cu / CN-0.4K exhibits the highest activity in catalyzing the hydrogenation of CO2 to ethanol, with a CO2 conversion rate of 48.11%, an ethanol selectivity of 47.36%, and a space-time yield of 7.32 mmol·g. cat -1 ·h -1 .

[0107] A comparison of Application Example 1 and Application Example 8 reveals that without alkali metal modification, the main product of the catalyst is alkanes. Introducing alkali metal K effectively suppresses *CH4. x Excessive hydrogenation leads to unsaturated *CH in the reaction. x The increased amount of alkali metal leads to a shift in products from alkanes to alkenes and alcohols, thereby improving the selectivity of ethanol. Furthermore, a comparison of Application Example 1 and Application Example 7 reveals that when alkali metal is in excess, the active surface of the catalyst may be covered by the alkali metal. This results in an excessive number of alkaline sites on the catalyst surface, leading to an overly strong adsorption capacity for CO2 and CO, which in turn causes carbon accumulation on the catalyst surface, resulting in reduced catalytic activity.

[0108] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0109] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A heteronuclear FeCu diatomic catalyst, characterized in that, The heteronuclear FeCu diatomic catalyst includes a support on which heteronuclear FeCu diatoms are loaded, and an additive element is also loaded on the support, wherein the additive element is at least one of potassium, sodium, and lithium.

2. The heteronuclear FeCu diatomic catalyst according to claim 1, characterized in that, In the carrier, the molar ratio of Fe to Cu in terms of atomic number is (4-12):(2-8).

3. The heteronuclear FeCu diatomic catalyst according to claim 1, characterized in that, In the carrier, the molar ratio of Fe to the added elements, in terms of atomic number, is (4-12):(0.4-1.2).

4. The heteronuclear FeCu diatomic catalyst according to claim 1, characterized in that, The carrier is a nitrogen-doped porous carbon material.

5. A method for preparing the heteronuclear FeCu diatomic catalyst according to claim 1, characterized in that, The preparation method includes the following steps: The carrier precursor, iron source, and copper source were dispersed in a solvent and reacted. After centrifugation, a solid product was obtained. The solid product was mixed with an additive containing the added elements and calcined under an inert atmosphere to obtain a heteronuclear FeCu diatomic catalyst.

6. The method for preparing the heteronuclear FeCu diatomic catalyst according to claim 5, characterized in that, The carrier precursor is at least one of melamine, urea, and dicyandiamide; and / or, The iron source is at least one of ferric nitrate, ferric sulfate, and ferric chloride; and / or, The copper source is at least one of copper nitrate, copper sulfate, and copper chloride; and / or, The additive is at least one of potassium chloride, sodium chloride, and lithium chloride.

7. The method for preparing the heteronuclear FeCu diatomic catalyst according to claim 5, characterized in that, The amount of the carrier precursor used is 5g-10g; and / or, The amount of iron source used is 4 mmol-12 mmol; and / or, The amount of copper source used is 2 mmol-8 mmol; and / or, The amount of the additive is 0.4 mmol to 1.2 mmol.

8. The method for preparing the heteronuclear FeCu diatomic catalyst according to claim 5, characterized in that, The carrier precursor, iron source, and copper source were dispersed in a solvent and reacted with stirring at 40℃-120℃ for 2-4 hours; after centrifugation, they were dried at 80℃-120℃ for 8-12 hours; and / or, The calcination temperature is 400℃-650℃, and the time is 4h-8h; and / or, After the calcination step is completed, the obtained product is cooled, and then ground, extruded and crushed. The particle size of the crushed product is 40-60 mesh, thus obtaining a heteronuclear FeCu diatomic catalyst.

9. The application of the heteronuclear FeCu diatomic catalyst according to claim 1 in the hydrogenation of CO2 to ethanol.

10. The application according to claim 9, characterized in that: Heteronuclear FeCu diatomic catalyst was mixed with 40-60 mesh quartz sand at a mass ratio of 1:(1-5) and packed into a reaction tube. Reduction was carried out at 300℃-600℃ for 2-8 hours under a hydrogen atmosphere. After reduction, the reaction was switched to a reaction gas, with a reaction temperature of 280℃-380℃, a reaction pressure of 2MPa-6MPa, and a reaction space velocity of 3000 mL·g⁻¹. cat -1 ·h -1 -12000mL·g cat -1 ·h -1 .

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