Preparation device and process of carbon material

Abstract

The invention relates to a preparation device and process of a carbon material, the preparation device comprises a mixer, a catalyst storage container, a carbon source storage container, a multi-section divergent reactor, a combined heating source and an induction heating device, the catalyst storage container and the carbon source storage container are respectively connected with the input end of the mixer so as to be favorable for conveying a catalyst and a carbon source into the mixer; the catalyst storage container and the carbon source storage container are respectively heated by an induction heating device; the output end of the mixer is connected with the inlet end of the multi-section diverging reactor, and the combined heating source is used for heating the multi-section diverging reactor. The reactor is heated by adopting a combined heating source, the catalyst and the carbon source are independently heated by virtue of the induction heating device, and the airflow flowing is optimized by adopting the multi-section divergent reactor, so that the catalyst activity is improved, the vortex interference is reduced, and the cracking efficiency of the carbon source is enhanced; the problems of catalyst agglomeration, low carbon source utilization rate, unstable airflow and the like in the existing FCCVD technology are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon nanomaterial preparation, and particularly relates to a preparation device and process for carbon materials. Background Art

[0002] Carbon nanotubes (CNTs) have wide applications in the fields of electronic devices, composite materials, energy storage devices, etc. due to their high strength, high conductivity, and excellent thermal properties. At present, the floating catalyst chemical vapor deposition method (FCCVD) is one of the main methods for large-scale preparation of carbon nanotubes. The FCCVD method carries catalyst particles into a high-temperature CVD reactor through gas, catalyzes the cracking of carbon sources, and promotes the growth of carbon nanotubes, having advantages such as high yield and continuous production capacity. However, there are still many challenges in the existing FCCVD system, which limit the quality and large-scale application of carbon nanotubes.

[0003] Although the FCCVD method has significant advantages in the industrial preparation of carbon nanotubes, the existing technology still has the following deficiencies: Traditional FCCVD devices use a single heat source (such as a tube furnace) to heat the catalyst and carbon source, resulting in overheating of the catalyst or insufficient cracking of the carbon source, affecting the growth uniformity of carbon nanotubes. The structural design of traditional CVD reactors is usually an equal-diameter or simple tube structure, and the gas flow is prone to form vortices and turbulence, resulting in uneven distribution of catalyst particles.

[0004] For the above reasons, carbon nanotubes prepared by the traditional FCCVD method generally have problems of low yield and low crystallinity, which limit the expansion of their fields. Summary of the Invention

[0005] The present invention makes improvements in view of the above problems existing in the prior art, that is, the technical problem to be solved by the present invention is to provide a preparation device and process for carbon materials.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A preparation device for carbon materials, including a mixer, a catalyst storage container, a carbon source storage container, a multi-stage gradually expanding reactor, a combined heating source, and an induction heating device. The catalyst storage container and the carbon source storage container are respectively connected to the input end of the mixer to facilitate the transportation of the catalyst and the carbon source into the mixer; each of the catalyst storage container and the carbon source storage container is heated by an induction heating device; the output end of the mixer is connected to the inlet end of the multi-stage gradually expanding reactor, and the combined heating source is used to heat the multi-stage gradually expanding reactor.

[0007] Further, the combined heating source is any combination of two of a tube furnace, a direct current heating device, a laser heating device, and a plasma heating device.

[0008] Further, the multi-stage gradually expanding reactor includes a plurality of straight pipe segments arranged coaxially and side by side, an expansion section is provided between two adjacent straight pipe segments, and a gradually expanding section is provided between each expansion section and the two adjacent straight pipe segments.

[0009] Further, the gradually expanding angle of the gradually expanding section is 5° to 20°.

[0010] Further, the induction heating device uses a high-frequency induction heating coil, and the frequency range of the high-frequency induction heating coil is 100 kHz to 1 MHz.

[0011] Further, a first mass flow controller is connected to the pipeline between the catalyst storage container and the mixer; a second mass flow controller is connected to the pipeline between the carbon source storage container and the mixer; a third mass flow controller is connected to the pipeline between the output end of the mixer and the inlet end of the multi-stage gradually expanding reactor; the catalyst is composed of a catalyst metal and a carrier, and the catalyst metal includes at least one of iron, cobalt, nickel, copper, palladium, platinum, titanium, manganese, aluminum, zinc, calcium, molybdenum, and tantalum, and the carrier includes at least one of alumina, silica gel, titanium dioxide, activated carbon, calcium oxide, and molecular sieve.

[0012] Further, it further includes a carrier gas conveying assembly, and the carrier gas conveying assembly is connected to the mixer to convey argon to the mixer.

[0013] Further, it further includes a carbon source conveying device, and the carbon source conveying device is used to convey a carbon source into the carbon source storage container.

[0014] Further, the outlet end of the multi-stage gradually expanding reactor is connected to a carbon nanotube collection device, and the carbon nanotube collection device is connected to an exhaust gas emission device.

[0015] Another technical solution adopted by the present invention is: a preparation process of a carbon material, including the following steps: Step S1: The combined heating source heats the multi-stage gradually expanding reactor to raise the internal temperature of the multi-stage gradually expanding reactor to 800°C - 1200°C; heats the catalyst storage container to make the catalyst particles reach 400°C - 600°C, and keeps it for 5 minutes to ensure catalyst activation; Step S2: Control the flow rate of the catalyst aerosol through the first mass flow controller to make its flow rate reach 10 - 20 sccm, and uniformly introduce it into the mixer; Step S3: Heat the carbon source storage container to a temperature of 400°C - 600°C, and adjust its flow rate to 100 - 200 sccm through the second mass flow controller, and uniformly introduce it into the mixer; Step S4: The carrier gas delivery component delivers argon to the mixer, and adjusts the argon flow rate to 300 sccm; Step S5: Adjust the third mass flow controller to make the flow rate of the mixed gas output from the mixer reach 100 - 300 sccm, maintain the reaction time for 30 min, and ensure the catalyst activity and the uniformity of carbon nanotube growth; Step S6: Stop the delivery of the carbon source and the catalyst, continue to introduce argon to cool the multi-stage gradually expanding reactor to prevent the catalyst from being over-oxidized; collect the carbon-containing mixed material, remove the catalyst by grinding, and obtain carbon nanotubes.

[0016] Compared with the prior art, the present invention has the following effects: The present invention is reasonably designed, uses a combined heating source to heat the reactor, independently heats the catalyst and the carbon source through an induction heating device, and at the same time uses a multi-stage gradually expanding reactor to optimize the gas flow, thereby improving the catalyst activity, reducing the eddy current interference, and enhancing the carbon source cracking efficiency, and solving the problems of catalyst agglomeration, low carbon source utilization rate, and unstable gas flow in the existing FCCVD technology. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of an embodiment of the present invention; Figure 2 is a Raman comparison diagram of carbon tubes prepared by the multi-stage gradually expanding reactor in the embodiment of the present invention at different temperatures.

[0018] In the figure: 1 - carrier gas delivery component; 2 - induction heating device; 3 - catalyst storage container; 4, second mass flow controller; 5 - mixer; 6 - carbon source storage container; 7, carbon source delivery device; 8 - multi-stage gradually expanding reactor; 9 - combined heating source; 10 - tail gas emission device; 11 - carbon nanotube collection device; 12 - straight pipe section; 13 - expansion section; 14 - gradually expanding section; 15 - inlet end; 16 - outlet end; 17 - first mass flow controller; 18 - third mass flow controller. Detailed Embodiments

[0019] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0021] As Figure 1 shown, a preparation device for a carbon material of the present invention includes a mixer 5, a catalyst storage container 3, a carbon source storage container 6, a multi-stage gradually expanding reactor 8, a combined heating source 9, and an induction heating device 2. The catalyst storage container 3 and the carbon source storage container 6 are respectively connected to two input ends of the mixer 5 through a conveying pipeline to facilitate the conveyance of the catalyst and the carbon source into the mixer 5, and the mixer mixes the carbon source and the catalyst; the catalyst storage container 3 and the carbon source storage container 6 are each independently heated by an induction heating device 2 so as to more precisely control the reaction conditions, reduce catalyst agglomeration, enable the carbon source to decompose sufficiently, and improve the growth quality and yield of carbon nanotubes; the output end of the mixer 5 is connected to the inlet end 15 of the multi-stage gradually expanding reactor 8, and the mixed gas output by the mixer 5 enters the multi-stage gradually expanding reactor through the inlet end. The combined heating source 9 is used to heat the multi-stage gradually expanding reactor 8. Using a combined heating source to heat the multi-stage gradually expanding reactor can adapt to different reaction conditions and improve the preparation flexibility. The multi-stage gradually expanding reactor is used to optimize the gas flow field distribution, reduce the formation of turbulence and eddy currents, and improve the uniform mixing of the gas and the catalyst.

[0022] In this embodiment, the combined heating source 9 is any two combinations of a tube furnace, a direct current heating device, a laser heating device, and a plasma heating device, which can adapt to different reaction conditions, improve the preparation flexibility, and ensure that the carbon source cracking temperature is stable at 800°C - 1200°C.

[0023] In this embodiment, the multi-stage gradually expanding reactor 8 includes a plurality of straight pipe segments 12 arranged coaxially and side by side. An expansion segment 13 is provided between two adjacent straight pipe segments 12, and a gradually expanding segment 14 is provided between each expansion segment 13 and the two adjacent straight pipe segments 12. Further, the gradually expanding angle of the gradually expanding segment is 5° to 20°. The reactor adopts a gradually expanding structure to optimize the gas flow distribution, reduce eddy currents, and improve the uniform mixing efficiency of the catalyst and the carbon source.

[0024] In this embodiment, the catalyst and the carbon source enter the mixer through different inlets to prevent the catalyst from coming into contact with the carbon source in advance and reduce the formation of by-products.

[0025] In this embodiment, the induction heating device 2 uses a high-frequency induction heating coil. The frequency range of the high-frequency induction heating coil is from 100 kHz to 1 MHz to ensure uniform heating of the catalyst particles and the carbon source. Non-contact heating is performed on the catalyst particles and the carbon source, so that the temperature of the catalyst is independently controlled at 400°C - 600°C, and the temperature of the carbon source is controlled at 400°C - 600°C.

[0026] In this embodiment, in order to facilitate flow control, a first mass flow controller 17 is connected to the pipeline between the catalyst storage container 3 and the mixer 5; a second mass flow controller 4 is connected to the pipeline between the carbon source storage container 6 and the mixer 5; a third mass flow controller 18 is connected to the pipeline between the output end of the mixer 5 and the inlet end of the multi-stage gradually expanding reactor 8. The first mass flow controller, the second mass flow controller, and the third mass flow controller are all mass flow meters (MFCs), which accurately adjust the flow rate of the mixed gas and improve the growth efficiency of carbon nanotubes.

[0027] It should be noted that the number of stages of the multi-stage gradually expanding reactor 8 can be selected according to experimental requirements.

[0028] In this embodiment, it further includes a carrier gas delivery assembly 1, and the carrier gas delivery assembly 1 is connected to the mixer 5 to deliver argon to the mixer.

[0029] In this embodiment, it further includes a carbon source delivery device 7, and the carbon source delivery device 7 is used to deliver the carbon source into the carbon source storage container 6.

[0030] In this embodiment, the outlet end 16 of the multi-stage gradually expanding reactor 8 is connected to a carbon nanotube collection device 11, and the carbon nanotube collection device 11 is connected to an exhaust gas emission device 10.

[0031] In this embodiment, the carbon source is methane, acetylene or ethanol, and is cracked to generate carbon nanotubes under the heating action of the combined heating source.

[0032] In this embodiment, the catalyst is composed of a catalyst metal and a carrier. The catalyst metal includes at least one of iron, cobalt, nickel, copper, palladium, platinum, titanium, manganese, aluminum, zinc, calcium, molybdenum and tantalum, and the carrier includes at least one of alumina, silica gel, titanium dioxide, activated carbon, calcium oxide and molecular sieve, and reaches 400°C to 600°C through induction heating to promote the growth of carbon nanotubes.

[0033] In this embodiment, the preparation process of the carbon material uses the above-mentioned carbon material preparation device and includes the following steps: Step S1: The combined heat source 9 heats the multi-stage gradually expanding reactor 8 to raise the internal temperature of the multi-stage gradually expanding reactor 8 to 800°C - 1200°C; heats the catalyst storage container 3 to bring the catalyst particles to 400°C - 600°C, and maintains for 5 minutes to ensure catalyst activation; Step S2: Control the flow rate of the catalyst aerosol through the first mass flow controller 17 to make its flow rate reach 10 - 20 sccm, and uniformly introduce it into the mixer 5; Step S3: Heat the carbon source storage container 6 to make its temperature reach 400°C - 600°C, make its flow rate reach 100 - 200 sccm through the second mass flow controller 4, and uniformly introduce it into the mixer 5; Step S4: The carrier gas delivery assembly 1 delivers argon to the mixer 5, and adjusts the argon flow rate to 300 sccm; Step S5: Adjust the third mass flow controller 18 to make the flow rate of the mixed gas output from the mixer 5 reach 100 - 300 sccm, maintain the reaction time for 30 min, and ensure catalyst activity and the growth uniformity of carbon nanotubes; Step S6: Stop the delivery of the carbon source and the catalyst, continue to introduce argon to cool the multi-stage gradually expanding reactor to prevent over-oxidation of the catalyst; collect the carbon-containing mixed material, remove the catalyst by grinding, and obtain carbon nanotubes.

[0034] Example 1: Step S1: The combined heat source adopts a combination of a tube furnace and a direct current heating device to raise the internal temperature of the reactor to 800°C; the induction heating device corresponding to the catalyst is turned on to bring the catalyst (metal-loaded catalyst, where the metal is 1% iron + 3% copper; the carrier is molecular sieve) to 500°C, and maintains for 5 minutes to ensure catalyst activation; Step S2: Precisely control the flow rate of the catalyst aerosol through the first mass flow controller to make its flow rate reach 10 sccm, and uniformly introduce it into the mixer; Step S3: Heat the carbon source (where the carbon source is ethanol) to make its temperature reach 500°C, make its flow rate reach 100 sccm through the second mass flow controller, and uniformly introduce it into the mixer; Step S4: Adjust the argon flow rate to 300 sccm; Step S5: Adjust the third mass flow controller to make the flow rate of the mixed gas reach 100 sccm, maintain the reaction time for 30 min, and ensure catalyst activity and the growth uniformity of carbon nanotubes; Step S6: Shut off the delivery of the carbon source and the catalyst, continue to introduce argon at 300 sccm to cool the reactor and prevent the catalyst from being over-oxidized; collect the carbon-containing mixed material, remove the catalyst by grinding to obtain carbon nanotubes, which are used as the product. The proportion of few-walled (1-2 layers) carbon nanotubes in the product is 75%, and G / D (crystallinity) is 14.2.

[0035] Example 2: Step S1: The combined heat source uses a combination of a tube furnace and a plasma device for heating to raise the internal temperature of the reactor to 900 °C. The induction heating device corresponding to the catalyst is turned on to heat the catalyst (metal-loaded catalyst, where the metal is 2% molybdenum + 3% platinum; the carrier is alumina) to 400 °C and maintain it for 5 minutes to ensure catalyst activation; Step S2: Precisely control the flow rate of the catalyst aerosol through the first mass flow controller (MFC) to make its flow rate reach 15 sccm and uniformly introduce it into the mixer; Step S3: Heat the carbon source (where the carbon source is acetylene), raise its temperature to 400 °C, make its flow rate reach 150 sccm through the second mass flow controller, and uniformly introduce it into the mixer; Step S4: Adjust the argon flow rate to 300 sccm; Step S5: Adjust the third mass flow controller to make the flow rate of the mixed gas reach 200 sccm, and maintain the reaction time for 30 min to ensure catalyst activity and the uniformity of carbon nanotube growth; Step S6: Shut off the delivery of the carbon source and the catalyst, continue to introduce argon at 300 sccm to cool the reactor and prevent the catalyst from being over-oxidized; collect the carbon-containing mixed material, remove the catalyst by grinding to obtain carbon nanotubes, which are used as the product. The proportion of few-walled (1-3 layers) carbon nanotubes in the product is 85%. G / D (crystallinity) is 21.

[0036] Example 3: Step S1: The combined heat source uses a combination of a laser heating device and a plasma heating device to raise the internal temperature of the reactor to 1000 °C. The induction heating device corresponding to the catalyst is turned on to heat the catalyst (metal-loaded catalyst, where the metal is 1% iron + 3% manganese + 6% cobalt; the carrier is 40% calcium oxide + 50% activated carbon) to 600 °C and maintain it for 5 minutes to ensure catalyst activation; Step S2: Precisely control the flow rate of the catalyst aerosol through the first mass flow controller (MFC) to make its flow rate reach 20 sccm and uniformly introduce it into the mixer; Step S3: Heat the carbon source (where the carbon source is methane gas), raise its temperature to 600 °C, make its flow rate reach 200 sccm through the second mass flow controller, and uniformly introduce it into the mixer; Step S4: Adjust the argon flow rate to 300 sccm; Step S5: Adjust the third mass flow controller to make the flow rate of the mixed gas reach 300 sccm, maintain the reaction time for 30 min, and ensure the catalyst activity and the growth uniformity of carbon nanotubes; Step S6: Shut off the delivery of the carbon source and the catalyst, continue to introduce 300 sccm of argon to cool the reactor, and prevent the catalyst from being over-oxidized; collect the carbon-containing mixed material, remove the catalyst by grinding, and obtain carbon nanotubes. These carbon nanotubes are used as products, and the proportion of few-walled (1-2 layers) carbon nanotubes in the products is 90%, and the G / D (crystallinity) is 38.

[0037] The present invention is an innovative reaction device especially aimed at vortex problems and energy consumption optimization. The device uses a combined heating source to provide heat energy for the reactor, and independently heats the catalyst particles and the carbon source through induction heating to achieve zone temperature control, improve the carbon source cracking efficiency and the catalyst activity. At the same time, a multi-stage gradually expanding reactor is adopted. By optimizing the geometric structure of the reactor, the formation of vortices is effectively suppressed, the gas flow uniformity is enhanced, and the growth rate and quality of carbon nanotubes are improved. The present invention has the advantages of high energy efficiency, low vortex interference, and high yield, and is suitable for the preparation of large-scale and high-quality carbon nanotubes.

[0038] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connected by bolts or screws), or it can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (for example, manufactured by integral forming using casting technology) (except when it is obviously impossible to adopt the integral forming process).

[0039] In addition, the terms used to represent the positional relationship or shape in any of the technical solutions disclosed in the present invention described above, unless otherwise stated, include states or shapes that are approximate, similar, or close to it.

[0040] Any component provided by the present invention can either be assembled from multiple separate components or be a single component manufactured by integral forming technology.

[0041] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements on some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A device for preparing carbon material, characterized in that: It includes a mixer, a catalyst storage container, a carbon source storage container, a multi-stage gradually expanding reactor, a combined heating source, and an induction heating device. The catalyst storage container and the carbon source storage container are respectively connected to the input end of the mixer to facilitate the transportation of the catalyst and the carbon source into the mixer; the catalyst storage container and the carbon source storage container are each heated by an induction heating device; the output end of the mixer is connected to the inlet end of the multi-stage gradually expanding reactor, and the combined heating source is used to heat the multi-stage gradually expanding reactor.

2. A carbon material preparation device according to claim 1, characterized in that: The combined heating source is any combination of two of a tubular furnace, a direct current heating device, a laser heating device, and a plasma heating device.

3. The carbon material preparation device according to claim 1, characterized in that: The multi-stage gradually expanding reactor comprises a plurality of coaxially arranged straight pipe sections, an expansion section is arranged between two adjacent straight pipe sections, and a gradually expanding section is arranged between each expansion section and two adjacent straight pipe sections.

4. A carbon material preparation device according to claim 3, characterized in that: The diverging angle of the diverging section is 5° to 20°.

5. The carbon material preparation device according to claim 1, characterized in that: The induction heating device adopts a high-frequency induction heating coil, and the frequency range of the high-frequency induction heating coil is 100 kHz to 1 MHz.

6. The carbon material preparation device according to claim 1, characterized in that: A first mass flow controller is connected to the conveying pipeline between the catalyst storage container and the mixer; a second mass flow controller is connected to the conveying pipeline between the carbon source storage container and the mixer; a third mass flow controller is connected to the conveying pipeline between the output end of the mixer and the inlet end of the multi-stage gradually expanding reactor; the catalyst is composed of a catalyst metal and a carrier, the catalyst metal includes at least one of iron, cobalt, nickel, copper, palladium, platinum, titanium, manganese, aluminum, zinc, calcium, molybdenum and tantalum, and the carrier includes at least one of alumina, silica gel, titanium dioxide, activated carbon, calcium oxide and molecular sieve.

7. The carbon material preparation device according to claim 1, characterized in that: It also includes a carrier gas delivery component, which is connected to the mixer and delivers argon gas to the mixer.

8. The carbon material preparation device according to claim 1, characterized in that: It also includes a carbon source conveying device, which is used to convey the carbon source into the carbon source storage container.

9. The carbon material preparation device according to claim 1, characterized in that: The outlet end of the multi-stage gradually expanding reactor is connected with a carbon nanotube collecting device, and the carbon nanotube collecting device is connected with a tail gas emission device.

10. A process for preparing a carbon material, characterized in that: A preparation device comprising the carbon material according to any one of claims 1 to 9, comprising the following steps: Step S1: The combined heating source heats the multi-stage gradually expanding reactor to raise the internal temperature of the multi-stage gradually expanding reactor to 800°C-1200°C; the catalyst storage container is heated to make the catalyst particles reach 400°C-600°C and maintained for 5 minutes to ensure catalyst activation; Step S2: controlling the flow rate of the catalyst aerosol by a first mass flow controller to reach a flow rate of 10-20 sccm, and uniformly introducing the catalyst aerosol into the mixer; Step S3: heating the carbon source storage container to a temperature of 400° C.-600° C., controlling the flow rate of the carbon source to 100-200 sccm through a second mass flow controller, and uniformly introducing the carbon source into the mixer; Step S4: the carrier gas delivery component delivers argon gas to the mixer, and the argon gas flow rate is adjusted to 300 sccm; Step S5: adjusting the third mass flow controller so that the flow rate of the mixed gas output by the mixer reaches 100-300 sccm, maintaining the reaction time for 30 min, and ensuring the catalyst activity and the uniformity of carbon nanotube growth; Step S6: stop delivering the carbon source and the catalyst, continue to introduce argon to cool the multi-stage gradually expanding reactor to prevent excessive oxidation of the catalyst; collect the carbon-containing mixed material, remove the catalyst by grinding, and obtain carbon nanotubes.

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