Efficient catalyst as well as preparation and application methods thereof

Abstract

The invention discloses a high-efficiency catalyst and a preparation and application method thereof, and relates to the technical field of nano carbon material preparation, the high-efficiency catalyst comprises the following components: an organic metal compound containing iron, cobalt and nickel, a refractory metal organic compound, a cocatalyst and a functional auxiliary agent, the catalyst is used for preparing the carbon nanotube by a floating chemical vapor deposition method, a high-temperature plasma CVD method or a plasma arc method, all components of the catalyst are uniformly mixed through melting granulation, the defect that the proportion is difficult to accurately control due to independent feeding is avoided, meanwhile, powder feeding can be cracked and evaporated in the subsequent carbon nanotube preparation process, and the carbon nanotube preparation efficiency is improved. The catalyst with higher concentration is obtained, and the preparation efficiency of the single-walled carbon nanotube is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanocarbon material preparation, and particularly provides a high-efficiency catalyst and a preparation and application method thereof. BACKGROUND

[0002] Single-walled carbon nanotubes can be regarded as one-dimensional tubular nanomaterials of single-layer graphite curling, and the super-strong carbon-carbon bond endows them with superior comprehensive performance, such as high strength, high modulus, high thermal conductivity and excellent electrical conductivity, and they have important applications in structural composites, electrochemical energy storage, catalysis and other fields.

[0003] At present, the preparation methods of single-walled carbon nanotubes mainly include arc discharge, laser ablation, plasma method and chemical vapor deposition method. Among them, the high-efficiency catalyst is a key link for preparing single-walled carbon nanotubes, and determines the final performance and yield of the product.

[0004] The existing high-temperature technical route for preparing single-walled carbon nanotubes mostly adopts the scheme of directly evaporating solid catalyst, which is difficult to control the evaporation rate, and the excessive catalyst leads to a large amount of catalyst not participating in the reaction in the product, resulting in low product purity. The chemical vapor deposition method using dilution reaction requires the feeding amount of the catalyst to be controlled at a very low level, such as the floating chemical vapor deposition method which dissolves ferrocene and a catalyst promoter in an organic solvent, resulting in too low a yield and being difficult to meet the requirements of industrialization. However, due to the poor flowability of the powder catalyst precursor, it is difficult to obtain a catalyst precursor mixture with accurate proportioning, especially the addition amount of some core promoters is very small, and it is more difficult to ensure the proportioning, so the development of high-efficiency catalyst and its preparation method is an important difficulty to be overcome for realizing large-scale preparation of single-walled carbon nanotubes. SUMMARY

[0005] In view of the above problems, the present application provides the following technical scheme: In one aspect, the present application provides a high-efficiency catalyst, and the components of the catalyst include an organic metal compound containing iron, cobalt and nickel, a refractory metal organic compound, a catalyst promoter and a functional promoter, and the composition ratio is as follows: Organic metal compound containing iron, cobalt and nickel 65-80% Refractory metal organic compound 5-20% Catalyst promoter 10-40% Functional promoter 5-20%.

[0006] Further, the organic metal compound containing iron, cobalt and nickel is any one of acetylacetone iron, acetylacetone nickel, acetylacetone cobalt, ferrocene, nickelocene and cobaltocene powder and a mixture of two or more thereof.

[0007] Furthermore, the refractory organometallic compound is an acetylacetone salt containing tantalum, molybdenum, tungsten, niobium, hafnium, or zirconium, including any one or a mixture of two or more of the following: tantalum acetylacetone, molybdenum acetylacetone, tungsten acetylacetone, niobium acetylacetone, hafnium acetylacetone, and zirconium acetylacetone.

[0008] Furthermore, the co-catalyst is a powder of sulfur, selenium, or ferrous sulfide; The functional additive is an additive that improves particle flowability, including any one or a mixture of two or more of graphite powder, carbon powder, molybdenum disulfide powder, and titanium disulfide powder, with a powder particle size of 200-1000 mesh.

[0009] In another aspect, the present invention provides a method for preparing a highly efficient catalyst, the method specifically comprising the following steps: S1) According to the component ratio, add the organometallic compound containing iron, cobalt and nickel, refractory organometallic compound, co-catalyst and functional additive powder into the reactor protected by inert gas, and heat up while stirring until the specified temperature is reached to melt the material. S2) The molten material is extruded and dripped through a screen into a cooling and solidification water bath. After rapid cooling, spherical particles are obtained. S3) The particles are filtered and separated from the water, and then vacuum dried to obtain the final catalyst particles.

[0010] Furthermore, in step S1), the inert gas is either nitrogen or argon, or a mixture thereof. The specified temperature is 175-250℃.

[0011] Furthermore, in step S2, the screen mesh size is 10-150 mesh; and the cooling and solidification water bath temperature is 4-30℃.

[0012] Furthermore, in step S3), the vacuum drying temperature is 40-70℃.

[0013] In another aspect, the present invention provides a method for using a highly efficient catalyst, wherein the catalyst is used to prepare carbon nanotubes, especially single-walled carbon nanotubes, by floating chemical vapor deposition, high-temperature plasma CVD, or plasma arc method. In use, the catalyst is directly placed into a reaction chamber at a furnace temperature of 1000-2000℃ for high-temperature pyrolysis. The catalyst rapidly evaporates to form catalyst nanoparticles, which combine and react with the pyrolysis products of organic carbon source to prepare carbon nanotubes.

[0014] Furthermore, the organic carbon source is any one of methane, ethane, propane, ethylene, propylene, or natural gas, and the mass ratio of the catalyst to the carbon source is 0.1:1 to 10:1.

[0015] Compared with existing technologies, the high-efficiency catalyst and its preparation and application methods of the present invention have the following outstanding advantages: (1) By melting and granulating, the components of the catalyst are mixed evenly, avoiding the inaccuracy of precise control of the ratio caused by individual feeding. At the same time, powder feeding can be decomposed and evaporated simultaneously in the subsequent carbon nanotube preparation process to obtain a higher concentration of catalyst, which significantly improves the preparation efficiency of single-walled carbon nanotubes. (2) Introducing functional additives that improve flowability into the catalyst not only makes the powder feeding of catalyst particles smoother and improves the powder feeding accuracy, but also allows some components, such as molybdenum disulfide, to participate in the catalytic reaction, resulting in better catalytic efficiency.

[0016] (3) The melt granulation process is adopted, which does not require any binder and avoids the negative effect of binder on subsequent catalytic reactions. Attached Figure Description

[0017] Figure 1 This is a flowchart of the catalyst preparation method of the present invention; Figure 2 Scanning electron microscope image of the carbon nanotube product prepared in this invention; Figure 3 The Raman spectrum of the carbon nanotube product prepared in this invention; Figure 4 This is a transmission electron microscope image of the carbon nanotube product prepared in this invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0019] like Figure 1 As shown, a method for preparing a high-efficiency catalyst includes the following steps: S1) According to the component ratio, add the organometallic compound containing iron, cobalt and nickel, refractory organometallic compound, co-catalyst and functional additive powder into the reactor protected by inert gas, and heat up while stirring until the specified temperature is reached to melt the material. S2) The molten material is extruded and dripped through a screen into a cooling and solidification water bath. After rapid cooling, spherical particles are obtained. S3) The particles are filtered and separated from the water, and then vacuum dried to obtain the final catalyst particles. Example 1

[0020] The catalyst composition was 85% ferrocene, 5% molybdenum acetylacetonate, 5% sulfur powder, and 5% graphite powder. Each component was added to a reactor protected with inert gas (N2) and heated to 150°C with stirring to melt the materials. The molten material was then extruded, passed through an 80-mesh sieve, and dripped into a cooling and solidification water bath. After rapid cooling, spherical particles were obtained. The particles were filtered from the water and dried under vacuum at 50°C to obtain the final catalyst particles. The catalyst's effectiveness was verified using thermal plasma CVD. The catalyst particles were directly fed into a floating chemical vapor deposition (CVD) reactor at 1250°C for high-temperature pyrolysis. The catalyst-to-ethylene ratio was 1:1. Rapid evaporation formed catalyst nanoparticles, which combined with and reacted with the pyrolysis products of the organic carbon source to prepare single-walled carbon nanotubes. The products were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Figure 2 The image shows the Raman spectroscopy characterization results. The peaks near 1250 cm⁻¹ and 1550 cm⁻¹ correspond to the D and G peaks, respectively. The G peak represents the degree of graphitization and crystallinity, while the D peak represents the non-graphitized structure. Therefore, the ratio of the two peak intensities, i.e., the IG / ID ratio, can be used to qualitatively determine the degree of graphitization and crystallinity of carbon nanotubes. Figure 2 The IG / ID ratio shown is 95. The morphology was observed using scanning electron microscopy (SEM), as follows... Figure 3 The image shown is its SEM image; its structure was observed and analyzed using transmission electron microscopy (TEM), such as... Figure 4 The TEM image shown shows single-walled and few-walled carbon nanotubes. Samples were calcined at 800 °C for 2 hours, and the ash content was weighed to calculate the carbon purity. Example 2

[0021] Catalyst composition: 65% ferrocene, 5% molybdenum acetylacetonate, 20% ferrous sulfide, and 10% molybdenum disulfide powder. The components were added to a reactor protected with inert gas (N2) according to the specified proportions, and the mixture was heated to 200℃ with stirring to melt the materials. The molten material was then extruded and dripped through a 150-mesh sieve into a cooling and solidification water bath. After rapid cooling, spherical particles were obtained. The particles were filtered from the water and dried under vacuum at 50℃ to obtain the final catalyst particles. The catalyst effect was verified using thermal plasma CVD. The catalyst particles were directly fed into a plasma arc reaction chamber at a furnace temperature of 1400℃ for high-temperature pyrolysis. The catalyst-to-methane ratio was 0.5:1. Rapid evaporation formed catalyst nanoparticles, which combined and reacted with the pyrolysis products of the organic carbon source to prepare single-walled carbon nanotubes. The products were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Samples were calcined at 800℃ for 2 hours, and the ash content was weighed to calculate the carbon purity. Example 3

[0022] The catalyst composition consisted of 70% ferric acetylacetonate, 5% molybdenum acetylacetonate, 15% ferrous sulfide, and 10% carbon powder. Each component was added to a reactor protected with inert gas (N2) and heated to 150°C with stirring to melt the materials. The molten material was then extruded, passed through a 50-mesh sieve, and dripped into a cooling and solidification water bath. After rapid cooling, spherical particles were obtained. The particles were then filtered from the water and dried under vacuum at 50°C to obtain the final catalyst particles. The catalyst's effectiveness was verified using thermal plasma CVD. The catalyst particles were directly fed into a plasma arc reaction chamber at 1300°C for high-temperature pyrolysis. The catalyst-to-natural gas ratio was 5:1. Rapid evaporation formed catalyst nanoparticles, which combined and reacted with the pyrolysis products of the organic carbon source to prepare single-walled carbon nanotubes. The products were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Samples were calcined at 800°C for 2 hours, and the ash content was weighed to calculate the carbon purity. Example 4

[0023] The catalyst composition consisted of 85% cobalt acetylacetonate, 5% molybdenum acetylacetonate, 5% sulfur powder, and 5% titanium disulfide. These components were added to a reactor protected with inert gas (N2) and heated to 150°C with stirring to melt the materials. The molten material was then extruded, passed through an 80-mesh sieve, and dripped into a cooling and solidification water bath. After rapid cooling, spherical particles were obtained. The particles were then filtered from the water and vacuum-dried at 50°C to obtain the final catalyst particles. The catalyst's effectiveness was verified using thermal plasma CVD. The catalyst particles were directly fed into a plasma arc reaction chamber at 1500°C for high-temperature pyrolysis. The catalyst-propylene ratio was 1:1. Rapid evaporation formed catalyst nanoparticles, which combined with the pyrolysis products of the organic carbon source and reacted to prepare single-walled carbon nanotubes. The products were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Samples were calcined at 800°C for 2 hours, and the ash content was weighed to calculate the carbon purity. Example 5

[0024] The catalyst composition consisted of 65% iron acetylacetonate, 20% cobalt acetylacetonate, 5% molybdenum acetylacetonate, 5% sulfur powder, and 5% graphite powder. These components were added to a reactor protected with inert gas (N2) and heated to 150°C with stirring to melt the materials. The molten material was then extruded, passed through an 80-mesh sieve, and dripped into a cooling and solidification water bath. After rapid cooling, spherical particles were obtained. The particles were then filtered from the water and vacuum-dried at 50°C to obtain the final catalyst particles. The catalyst's effectiveness was verified using thermal plasma CVD. The catalyst particles were directly fed into a plasma arc reaction chamber at 1700°C for high-temperature pyrolysis, rapidly evaporating to form catalyst nanoparticles. These nanoparticles combined with the pyrolysis products of the organic carbon source and reacted to prepare single-walled carbon nanotubes. The products were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Samples were calcined at 800°C for 2 hours, and the ash content was weighed to calculate the carbon purity.

[0025] The data for each embodiment are summarized in Table 1.

[0026] Table 1 Example Catalyst component Carbon nanotube preparation method I G / I D ]]> Purity Example 1 Ferrocene 85% - Molybdenum acetylacetonate 5% - Sulfur powder 5% - Graphite powder 5% FCCVD 95 92% Example 2 Ferrocene 65% - Molybdenum acetylacetonate 5% - Ferrous sulfide 20% - Molybdenum disulfide powder 10% Thermal plasma CVD method 74 82% Example 3 Iron acetylacetonate 70% - Molybdenum acetylacetonate 5% - Ferrous sulfide 15% - Carbon powder 10% Plasma arc method 87 75% Example 4 Cobalt acetylacetonate 85% - Molybdenum acetylacetonate 5% - Sulfur powder 5% - Titanium disulfide 5% Plasma arc method 65 78% Example 5 Iron acetylacetonate 65% - Cobalt acetylacetonate 20% - Molybdenum acetylacetonate 5% - Sulfur powder 5% - Graphite powder 5% Plasma arc method 78 82% The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solutions of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly efficient catalyst, characterized in that, The catalyst comprises: an organometallic compound containing iron, cobalt, and nickel; a refractory organometallic compound; a co-catalyst; and functional additives, in the following proportions: Organometallic compounds containing iron, cobalt, and nickel account for 65-80%. Refractory organometallic compounds 5-20% 10-40% co-catalyst Functional additives: 5-20%.

2. The high-efficiency catalyst according to claim 1, characterized in that, The organometallic compound containing iron, cobalt, and nickel is any one or a mixture of two or more of acetylacetone iron, acetylacetone nickel, acetylacetone cobalt, ferrocene, nickel succinate, and cobalt succinate powder.

3. A high-efficiency catalyst according to claim 1 or 2, characterized in that, The refractory organometallic compound is an acetylacetone salt containing tantalum, molybdenum, tungsten, niobium, hafnium or zirconium refractory metals, including any one or a mixture of two or more of tantalum acetylacetone, molybdenum acetylacetone, tungsten acetylacetone, niobium acetylacetone, hafnium acetylacetone, and zirconium acetylacetone.

4. The high-efficiency catalyst according to claim 3, characterized in that, The co-catalyst is a powder of sulfur, selenium, or ferrous sulfide; The functional additive is an additive that improves particle flowability, including any one or a mixture of two or more of graphite powder, carbon powder, molybdenum disulfide powder, and titanium disulfide powder, with a powder particle size of 200-1000 mesh.

5. A method for preparing a high-efficiency catalyst based on any one of the high-efficiency catalysts described in claims 1-4, characterized in that, The preparation method specifically includes the following steps: S1) According to the component ratio, add the organometallic compound containing iron, cobalt and nickel, refractory organometallic compound, co-catalyst and functional additive powder into the reactor protected by inert gas, and heat up while stirring until the specified temperature is reached to melt the material. S2) The molten material is extruded and dripped through a screen into a cooling and solidification water bath. After rapid cooling, spherical particles are obtained. S3) The particles are filtered and separated from the water, and then vacuum dried to obtain the final catalyst particles.

6. The method for preparing a high-efficiency catalyst according to claim 5, characterized in that, In step S1), the inert gas is either nitrogen or argon, or a mixture thereof. The specified temperature is 175-250℃.

7. The method for preparing a high-efficiency catalyst according to claim 6, characterized in that, In step S2, the screen mesh size is 10-150 mesh; the cooling and solidification water bath temperature is 4-30℃.

8. The method for preparing a high-efficiency catalyst according to claim 7, characterized in that, In step S3), the vacuum drying temperature is 40-70℃.

9. A method for applying a highly efficient catalyst based on any of the preceding claims, characterized in that, The catalyst is used to prepare carbon nanotubes by floating chemical vapor deposition, high-temperature plasma CVD, or plasma arc method. When in use, it is directly put into a reaction chamber with a furnace temperature of 1000-2000℃ for high-temperature pyrolysis. The catalyst rapidly evaporates to form catalyst nanoparticles, which combine and react with the pyrolysis products of organic carbon source to prepare carbon nanotubes.

10. The method for applying a high-efficiency catalyst according to claim 9, characterized in that, The organic carbon source is any one of methane, ethane, propane, ethylene, propylene, or natural gas, and the mass ratio of catalyst to carbon source is 0.1:1 to 10:1.

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