A carbon-based material processing system and application

Abstract

The present invention discloses a carbon-based material processing system and application, the system includes at least one chamber, the interior of the chamber is filled with carbon-based materials to be purified, the chamber includes chamber side walls, a graphite chamber bottom and a graphite chamber cover, the graphite chamber bottom is connected to a hollow first graphite tube, the graphite chamber cover is connected to a hollow second graphite tube, the first graphite tube and the second graphite tube are both connected to the interior of the chamber, the first graphite tube is connected to an external power source as a lower electrode, and the second graphite tube is connected to an external power source as an upper electrode. The carbon-based material processing system can be used to purify and / or graphitize carbon-based materials. Compared with the traditional Acheson furnace, the carbon-based material processing system of the present invention does not require a large number of graphite crucibles, nor does it need to fill the outside of the crucible with resistive fillers such as petroleum coke. The present invention uses electric current to pass through the carbon-based material, utilizes Joule heat, and directly heats it, has high heating efficiency, and greatly saves electricity.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-based materials, and in particular relates to a carbon-based material processing system and application. Background Art

[0002] Carbon nanotubes have attracted much attention due to their unique structural characteristics, unique physical and chemical properties and potential application value in future high-tech fields. They have become the research frontier and hotspot in physics, chemistry, biology, materials and other fields, and have broad application prospects in many fields such as nanoelectronic devices, catalyst carriers, electrochemical materials, composite materials, etc.

[0003] The existing methods for preparing carbon nanotubes mainly include arc discharge method, laser etching method, chemical vapor deposition method, solid phase pyrolysis method, flame synthesis method, glow discharge method and polymerization reaction synthesis method. Among the many carbon nanotube preparation processes, except for some DC arc methods that do not require catalysts, other methods all require the participation of catalysts. Most catalysts are transition metals such as iron, cobalt, nickel, manganese and their oxides. With the growth of carbon nanotubes, the metal active components will be coated by the carbon layer, resulting in the deactivation of the catalyst, so that the metal catalysts will inevitably remain in the obtained carbon nanotube crude product. The presence of these metal impurities will directly affect the performance of carbon nanotubes, thereby greatly restricting the application of carbon nanotubes in many fields. Therefore, in order to obtain high-purity carbon nanotubes, the carbon nanotube crude product must be purified.

[0004] The process of removing metal impurities from carbon nanotubes is called purification. At present, the Acheson graphitization furnace is mostly used to remove metal catalysts from carbon nanotubes. The industrial application of Acheson furnace has a history of 100 years and is still widely used in my country. The characteristics of this furnace are simple structure, durability and easy maintenance. Despite this, the Acheson process also has many problems, such as large heat loss, high purification temperature, and only about 30% effective energy utilization rate. In addition, a large amount of petroleum coke is required as a resistor material, which causes serious pollution. Acheson furnace purification also requires a large amount of graphite crucibles. A single crucible is filled with a small amount of material and is easily damaged, consuming a large amount of graphite resources.

[0005] In order to solve the above problems in the prior art, the present invention is provided. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a carbon-based material processing system and application. The present invention does not use a large number of graphite crucibles required by the Acheson furnace, nor does it need to fill the outside of the crucible with resistive fillers such as petroleum coke; except for a small amount of graphite paper, there is basically no loss of auxiliary materials; the present invention uses electric current to pass through the carbon-based material and utilizes Joule heat to directly heat it, with high heating efficiency, uniform temperature, and short heating time, which greatly saves electricity and auxiliary materials, and the halogen gas used is recycled, which helps to reduce environmental pollution.

[0007] The technical solution of the present invention is:

[0008] The present invention relates to a carbon-based material processing system, comprising at least one cabin, wherein the interior of the cabin is filled with carbon-based materials to be purified, wherein the cabin comprises cabin side walls, a graphite cabin bottom and a graphite cabin cover, wherein the graphite cabin bottom is connected to a first hollow graphite tube, and the graphite cabin cover is connected to a second hollow graphite tube, wherein the first graphite tube and the second graphite tube are both connected to the interior of the cabin, wherein the first graphite tube is connected to an external power supply as a lower electrode, and the second graphite tube is connected to an external power supply as an upper electrode.

[0009] Preferably, the top surface of the graphite cabin cover is paved with a thermal insulation material layer and a gas absorption layer, and the gas absorption layer is composed of lime powder.

[0010] Preferably, the graphite tank bottom is composed of a bottom base and a bottom protrusion, and the bottom protrusion is located inside the cabin, so that the graphite tank bottom is partially inside the cabin and partially outside the cabin. It is further preferred that the upper 1 / 3 of the graphite tank bottom is inside the cabin and the lower 2 / 3 is outside the cabin.

[0011] The graphite cabin cover consists of a cover base and a cover protrusion, and the cover protrusion is located inside the cabin, so that the graphite cabin cover is partially inside the cabin and partially outside the cabin. It is further preferred that the lower 1 / 3 of the graphite cabin cover is inside the cabin and the upper 2 / 3 is outside the cabin.

[0012] Preferably, the first graphite tube is connected to the air intake source, and the second graphite tube is connected to the absorption filter chamber, and the metal impurities inside the carbon-based material are oxidized into low-boiling point halides and enter the gas absorption filter chamber through the second graphite tube.

[0013] Preferably, the cabin side walls are made of refractory bricks; the inner side of the cabin side walls and the inner side of the graphite tank bottom are provided with a graphite insulation layer, which is first sprayed with graphite emulsion and then pasted with graphite paper to form a graphite insulation layer. The graphite paper in the cabin can be replaced in time according to the damage.

[0014] Preferably, the side wall of the cabin is provided with at least one temperature measuring channel, and further preferably three temperature measuring channels, which are respectively located at the upper, middle and lower sides. The temperature measuring channel is a reserved graphite tube with a closed top, and the top of the graphite tube is inserted into the center of the cabin.

[0015] Preferably, the number of the cabins is at least two, and the cabins are connected in parallel, which helps to fully utilize space and effectively utilize energy.

[0016] Preferably, the cross-sectional shape of the cabin side wall is a triangle, a square, or a regular hexagon.

[0017] Preferably, the first graphite tube and the second graphite tube are threaded graphite tubes, the first graphite tube is threadedly connected to the graphite tank bottom, and the second graphite tube is threadedly connected to the graphite cabin cover.

[0018] The manufacturing method of the above-mentioned carbon-based material processing system comprises the following steps:

[0019] S1. Use refractory bricks to build the side walls of the cabin, and lay the bottom with graphite blocks to make it flat as a graphite bottom, with part of the graphite bottom inside the cabin and part outside the cabin; more preferably, the upper 1 / 3 of the graphite bottom is inside the cabin and the lower 2 / 3 is outside the cabin;

[0020] S2. A graphite isolation layer is arranged on the inner side of the graphite tank bottom and the inner side of the cabin side wall; specifically, graphite emulsion can be sprayed first, and graphite paper can be pasted, and the graphite paper can be spliced ​​to form a complete graphite isolation layer;

[0021] S3, filling the chamber with the carbon-based material to be purified, and compacting and flattening it by gravity;

[0022] S4, splicing multiple graphite blocks, opening grooves on the outer side, spraying graphite emulsion with carbon fiber rope, combining the graphite blocks into a graphite cabin cover, compacting the carbon-based material in the cabin, and the graphite cabin cover is partially inside the cabin and partially outside the cabin; further preferably, the lower 1 / 3 of the graphite cabin cover is inside the cabin, and the upper 2 / 3 is outside the cabin;

[0023] It is further preferred that a thermal insulation material is laid on the top surface of the graphite cabin cover to form a thermal insulation material layer, and then lime powder is laid on it as a gas absorption layer;

[0024] S5. Open a gas channel at the bottom of the graphite tank and connect it to a first graphite tube, and open a gas channel at the graphite cabin cover and connect it to a second graphite tube; the first graphite tube and the second graphite tube are further preferably threaded graphite tubes, and accordingly, the first graphite tube is threadedly connected to the bottom of the graphite tank, and the second graphite tube is threadedly connected to the graphite cabin cover;

[0025] S6. The first graphite tube is connected to an external power source as a lower electrode, the second graphite tube is connected to an external power source as an upper electrode, the inside is ventilated, the first graphite tube is connected to an air inlet source, and the second graphite tube is connected to an absorption filter chamber to form a carbon-based material processing system.

[0026] Preferably, graphite tubes with closed tops are reserved at the upper, middle and lower sides of the cabin, and the tops of the graphite tubes are horizontally inserted into the center of the cabin to serve as temperature measurement channels for infrared monitoring of the temperature of carbon-based materials in the cabin.

[0027] Preferably, a plurality of cabins are manufactured and connected in parallel, thereby making full use of space and effectively utilizing energy.

[0028] The present invention also relates to the application of the above carbon-based material processing system in the purification and / or graphitization of carbon-based materials. The carbon-based material may be a carbon nanotube or other carbon-based materials such as a graphite anode.

[0029] Preferably, the purification process of the carbon-based material is as follows: when the upper electrode and the lower electrode are electrically heated, a halogen gas is introduced to purify the carbon-based material inside the chamber, and the metal impurities inside the carbon-based material are oxidized into low-boiling-point halides;

[0030] The halogen gas is chlorine gas or bromine or iodine vapor;

[0031] The purification treatment temperature is 800-1500° C., and the purification treatment time is 0.5-20 hours.

[0032] When only purification treatment is required, more preferably, the purification treatment method of the carbon-based material comprises the following steps

[0033] Step 1: Inert gas is introduced into the first graphite tube, and then the upper electrode and the lower electrode are electrically heated and slowly heated to a specified temperature of 800-1500°C, and then the introduced gas is switched to halogen gas;

[0034] Step 2: Continue to keep warm and ventilate to purify the carbon-based material inside the cabin for 0.5-20 hours, and the metal impurities inside the carbon-based material are oxidized into low-boiling-point halides;

[0035] Step 3: Then switch the incoming gas to inert gas, cut off the power, and cool down naturally to complete the purification process of the carbon-based material.

[0036] Preferably, the graphitization process of the carbon-based material is as follows: when the upper electrode and the lower electrode are electrically heated, an inert gas is introduced to graphitize the carbon-based material inside the chamber, so as to convert the carbon-based material from an amorphous carbon structure to a crystalline graphite structure;

[0037] The inert gas is nitrogen or argon; the carbon-based material is carbon nanotubes;

[0038] The graphitization treatment temperature is 2800-3000° C., and the graphitization treatment time is 10-100 hours.

[0039] Preferably, when purifying and graphitizing the carbon-based material, the purification treatment is performed first, and then the temperature is raised to 2500-2800°C. After the halogen gas is switched to an inert gas, the temperature is further raised to 2800-3000°C to graphitize the carbon-based material.

[0040] When purification and graphitization are required, more preferably, the purification and graphitization method of the carbon-based material comprises the following steps:

[0041] Step 1: Inert gas is introduced into the first graphite tube, and then the upper electrode and the lower electrode are electrically heated and slowly heated to a specified temperature of 800-1500°C, and then the introduced gas is switched to halogen gas;

[0042] Step 2: Continue to keep warm and ventilate to purify the carbon-based material inside the cabin for 0.5-20 hours, and the metal impurities inside the carbon-based material are oxidized into low-boiling-point halides;

[0043] Step 3: Continue to pass the halogen gas, continue to heat up to a temperature of 2500-2800°C, switch the halogen gas to an inert gas, continue to heat up to a temperature of 2800-3000°C, and keep the temperature for a sufficient time to graphitize the carbon-based material, the time is 10-100 hours, and the carbon-based material is converted from an amorphous carbon structure to a crystalline graphite structure;

[0044] Step 4: Then continue to ventilate, turn off the power, and cool naturally to complete the purification and graphitization of the carbon-based material.

[0045] The beneficial effects of the present invention are:

[0046] 1) The present invention uses electric current to pass through carbon-based materials and utilizes Joule heat to directly heat them. The heating efficiency is high and the temperature is uniform. The purification temperature of carbon-based materials is more than 200°C lower than that of the existing process, the time is shortened by 20%, the power saving is more than 10%, and the single processing capacity is increased by 5 times;

[0047] 2) The halogen gas used in the purification method of the present invention can be recycled, the halide + halogen gas source enters the saturated salt water, the halide is absorbed, and the halogen gas is recycled, which helps to reduce environmental pollution;

[0048] 3) The present invention is also provided with a gas absorption layer, which is composed of lime powder. The lime powder absorbs the halogen gas leaked from the gaps in the cabin to form calcium halide, which can be used as a desiccant. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0050] Figure 1 Cross-sectional view of a carbon-based material handling system after filling it with carbon-based material.

[0051] Markings in the figure are: 1. Cabin side wall; 2. Graphite cabin bottom; 21. Bottom base; 22. Bottom protrusion; 3. Graphite cabin cover; 31. Cover base; 32. Cover protrusion; 4. First graphite tube; 5. Second graphite tube; 6. Absorption filter chamber; 7. Insulation material layer; 8. Gas absorption layer; 9. Temperature measurement channel. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific embodiments. Experimental methods without specific conditions in the examples are carried out according to conventional methods and conditions.

[0053] Example 1

[0054] This embodiment provides a carbon-based material processing system, which has the advantages of low purification temperature, high heating efficiency, short heating time, substantial energy saving, no need for resistor fillers, and recyclable halogen gas.

[0055] like Figure 1 As shown, the carbon-based material processing system includes a cabin, which includes a cabin side wall 1, a graphite cabin bottom 2 and a graphite cabin cover 3. The cabin side wall 1, the graphite cabin bottom 2 and the graphite cabin cover 3 together enclose the cabin internal space for filling carbon-based materials. The graphite cabin bottom 2 is composed of a bottom base 21 and a bottom protrusion 22. The bottom protrusion 22 is located inside the cabin, so that the upper 1 / 3 of the graphite cabin bottom 2 is inside the cabin and the lower 2 / 3 is outside the cabin. The graphite cabin cover 3 is composed of a cover base 31 and a cover protrusion 32. The cover protrusion 32 is located inside the cabin, so that the lower 1 / 3 of the graphite cabin cover 3 is inside the cabin and the upper 2 / 3 is outside the cabin. The cabin side wall 1 is made of refractory bricks; the inner side of the cabin side wall and the inner side of the cabin bottom are provided with a graphite isolation layer, which is first sprayed with graphite emulsion and then pasted with graphite paper to form a graphite isolation layer. The graphite paper in the cabin can be replaced in time according to the damage.

[0056] The graphite tank bottom 2 is connected to a hollow first graphite tube 4, and the graphite cabin cover 3 is connected to a hollow second graphite tube 5. The first graphite tube 4 and the second graphite tube 5 are both connected to the interior of the cabin. The first graphite tube 4 and the second graphite tube 5 are threaded graphite tubes. The first graphite tube 4 is threadedly connected to the graphite tank bottom 2, and the second graphite tube 5 is threadedly connected to the graphite cabin cover 3. The first graphite tube 4 is connected to an external power source as a lower electrode, and the second graphite tube 5 is connected to an external power source as an upper electrode. The first graphite tube 4 is connected to an air intake source, and the second graphite tube 5 is connected to an absorption filter chamber 6. The metal impurities inside the carbon-based material are oxidized into low-boiling-point halides and enter the gas absorption filter chamber through the second graphite tube.

[0057] The top surface of the graphite cabin cover 3 is paved with a heat-insulating material layer 7 and a gas absorption layer 8. The gas absorption layer 8 is composed of lime powder, which absorbs the halogen gas leaked from the cabin gap.

[0058] In addition, three temperature measuring channels 9 are provided on the side wall of the cabin, respectively located at the upper, middle and lower sides, for infrared monitoring of the temperature of the carbon-based materials in the cabin. The temperature measuring channels are reserved graphite tubes with closed tops, and the tops of the graphite tubes are inserted into the center of the cabin.

[0059] The manufacturing method of the carbon-based material processing system comprises the following steps:

[0060] S1, a square cabin with a length, width and height of one meter is built using high-temperature refractory bricks, and the bottom is paved with graphite blocks to form a graphite bottom; the upper 1 / 3 of the graphite bottom is inside the cabin, and the lower 2 / 3 is outside the cabin.

[0061] S2, spray graphite emulsion and paste graphite paper on the bottom and inner wall of the cabin. The graphite paper can be spliced ​​to form a complete graphite isolation layer;

[0062] S3, the interior of the cabin is filled with carbon-based materials, compacted and flattened by gravity;

[0063] S4, which is made of multiple graphite blocks spliced ​​together, grooves are cut on the outer side, graphite emulsion is sprayed on carbon fiber ropes, and the graphite blocks are combined into a graphite cabin cover, and the carbon-based materials in the cabin are compacted; the lower 1 / 3 of the graphite cabin cover is inside the cabin, and 2 / 3 is outside the cabin; the upper part is covered with insulation material to form an insulation material layer, and then covered with lime powder as a gas absorption layer;

[0064] S5, the graphite tank bottom and the graphite cabin cover are both provided with circular threaded holes on the side and inner holes in the middle, the surface of the graphite threaded tube is sprayed with graphite emulsion, and the tube is screwed into the graphite body to form a gas passage that switches horizontally to vertically; the first graphite tube is threadedly connected to the graphite tank bottom, and the second graphite tube is threadedly connected to the graphite cabin cover;

[0065] S6, the graphite threaded tube is connected to an external power source as the upper and lower electrodes; the first graphite tube is connected to the air source, and the second graphite tube is connected to the gas absorption filter chamber to form a carbon-based material processing system;

[0066] S7, reserved graphite tubes with closed tops on the upper, middle and lower sides of the cabin, with the tops inserted horizontally into the center of the cabin to serve as temperature measurement channels for infrared monitoring of the temperature of carbon-based materials in the cabin.

[0067] Example 2

[0068] The carbon-based material processing system of Example 1 is used to purify the carbon-based material, comprising the following steps, wherein the carbon-based material filled in the chamber is single-walled carbon nanotubes, with a metal impurity mass content of 1.51% and an ash content of 2.60%:

[0069] Step 1, nitrogen gas is passed through the first graphite tube at a nitrogen flow rate of 10 L / min, and then the upper electrode and the lower electrode are electrically heated at a rate of 5°C / min to a specified temperature of 1200°C, and then the gas is switched to chlorine gas;

[0070] Step 2, continue to keep warm and ventilate for 60 minutes to purify the single-walled carbon nanotubes with high-temperature halogen; the metal impurities inside the single-walled carbon nanotubes are oxidized into low-boiling point halides and enter the gas absorption filter chamber through the second graphite tube;

[0071] Step 3, switch the gas to nitrogen, cut off the power, and cool naturally to complete the purification of the single-walled carbon nanotubes.

[0072] The purified single-walled carbon nanotubes were collected by a vacuum collecting system. The ash content of the purified single-walled carbon nanotubes was 0% and the metal impurity content was 3.3 ppm.

[0073] Example 3

[0074] The carbon-based material processing system of Example 1 is used to purify and graphitize the carbon-based material, including the following steps, wherein the carbon-based material filled in the chamber is multi-walled carbon nanotubes, the metal impurity mass content is 1.42%, and the ash content is 2.57%:

[0075] Step 1, argon gas is passed through the first graphite tube at a flow rate of 15 L / min, and then the upper electrode and the lower electrode are electrically heated at a rate of 5°C / min to a specified temperature of 1000°C, and then the gas is switched to iodine vapor;

[0076] Step 2, continue to keep warm and ventilate for 80 minutes to purify the multi-walled carbon nanotubes with high-temperature halogen; the metal impurities inside the multi-walled carbon nanotubes are oxidized into low-boiling point halides and enter the gas absorption filter chamber through the second graphite tube;

[0077] Step 3, continue to pass iodine vapor, continue to raise the temperature to 2800° C., switch the iodine vapor to argon gas, continue to raise the temperature to 3000° C., and keep the temperature for 20 hours to graphitize the multi-walled carbon nanotubes, thereby converting the multi-walled carbon nanotubes from an amorphous carbon structure to a crystalline graphite structure;

[0078] Step 4, continue to ventilate, turn off the power, and cool naturally to complete the purification and graphitization of the multi-walled carbon nanotubes.

[0079] After purification and graphitization, the multi-walled carbon nanotubes obtained had an ash content of 0%, a metal impurity content of 1.2 ppm, and a graphitization degree of 82%.

[0080] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A carbon-based material processing system, comprising at least one chamber, wherein the chamber is filled with a carbon-based material to be purified, characterized in that: The cabin comprises a cabin side wall, a graphite cabin bottom and a graphite cabin cover, the graphite cabin bottom is connected to a first hollow graphite tube, the graphite cabin cover is connected to a second hollow graphite tube, the first graphite tube and the second graphite tube are both connected to the interior of the cabin, the first graphite tube is connected to an external power source as a lower electrode, and the second graphite tube is connected to an external power source as an upper electrode; The graphite tank bottom is composed of a bottom base and a bottom protrusion, and the bottom protrusion is located inside the cabin, so that the graphite tank bottom is partially inside the cabin and partially outside the cabin; the graphite cabin cover is composed of a cover base and a cover protrusion, and the cover protrusion is located inside the cabin, so that the graphite cabin cover is partially inside the cabin and partially outside the cabin; The inner side of the side wall of the cabin and the inner side of the graphite tank bottom are both provided with a graphite isolation layer, which is firstly sprayed with graphite emulsion and then pasted with graphite paper to form the graphite isolation layer.

2. The carbon-based material processing system according to claim 1, characterized in that: The top surface of the graphite cabin cover is paved with a heat-insulating material layer and a gas-absorbing layer, and the gas-absorbing layer is composed of lime powder.

3. The carbon-based material processing system according to claim 1, characterized in that: The upper 1 / 3 of the graphite tank bottom is inside the cabin, and the lower 2 / 3 is outside the cabin; the lower 1 / 3 of the graphite cabin cover is inside the cabin, and the upper 2 / 3 is outside the cabin.

4. The carbon-based material processing system according to claim 1, characterized in that: The first graphite tube is connected to an air intake source, and the second graphite tube is connected to an absorption filter chamber.

5. The carbon-based material processing system according to claim 1, characterized in that: The side wall of the cabin is provided with at least one temperature measuring channel.

6. The carbon-based material processing system according to claim 1, characterized in that: The number of the cabins is at least two, and the cabins are connected in parallel.

7. Use of the carbon-based material processing system according to any one of claims 1 to 6 in purification and / or graphitization of carbon-based materials.

8. The use according to claim 7, characterized in that: The purification process of the carbon-based material is as follows: when the upper electrode and the lower electrode are powered on and heated, halogen gas is introduced to purify the carbon-based material inside the chamber, and the metal impurities inside the carbon-based material are oxidized into low-boiling-point halides; The halogen gas is chlorine gas or bromine or iodine vapor; The purification treatment temperature is 800-1500° C., and the purification treatment time is 0.5-20 hours.

9. The use according to claim 7, characterized in that: The graphitization process of the carbon-based material is as follows: when the upper electrode and the lower electrode are electrically heated, an inert gas is introduced to graphitize the carbon-based material inside the chamber, and the carbon-based material is converted from an amorphous carbon structure to a crystalline graphite structure; Wherein the inert gas is nitrogen or argon; The graphitization treatment temperature is 2800-3000° C., and the graphitization treatment time is 10-100 hours.

10. According to the application described in claim 7, when purifying and graphitizing the carbon-based material, the purification treatment is first carried out, and then the temperature is raised to 2500-2800°C. After the halogen gas is switched to an inert gas, the temperature is further raised to 2800-3000°C to graphitize the carbon-based material.

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