RU2424184C2 - Reactor for synthesis of carbon nanotubes - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of fibrous carbon materials via pyrolysis of aromatic and not aromatic hydrocarbons. First, catalyst is sprayed in proportioning and precipitation apparatus. Container 6 with precipitated catalyst is transferred on disk by manipulator 3. Heaters arranged above said disk and its rotation drive are cut in. Carbon-containing gas is fed under gas distribution casing. Unreacted gas and pyrolysis gaseous products are discharged via reaction gas bleed branch pipes. After synthesis of carbon nanotubes carbon-containing gas feed is terminated and heaters are switched off. Cooling is switched on. Container 6 with synthesised nanotubes is withdrawn after depressurisation of reactor.

EFFECT: higher quality of synthesised carbon material and efficiency of reactor.

2 cl, 9 dwg

Description

The invention relates to a technology for producing fibrous carbon materials by the pyrolysis of aromatic and non-aromatic hydrocarbons.

A device is known that allows you to process the source of gaseous hydrocarbon products. In US patent No. 5165909, IPC D01F 9/10, 1992, preference is given to gases such as acetylene (carbonization temperature 500 ° C) and methane (carbonization temperature below 1000 ° C). According to the patent, pyrolysis is carried out in a vertical furnace, in the upper part of which there is a pipe for supplying hydrocarbon gas, belt heaters and a hopper with a catalyst. A feed valve is installed at the bottom of the catalyst hopper, which feeds the catalyst into the reaction zone of the furnace in the form of powdered nickel with the addition of aluminum. At the bottom there is a second hydrocarbon gas supply pipe. The distance between the feed valve and the second hydrocarbon gas supply pipe is the reaction zone, below which is the base of the furnace, equipped with a filter, which is the collection of the finished product before unloading.

However, in such a furnace, the resulting pyrolysis products are subjected to prolonged heating by circulating hot gas containing a mixture of hydrocarbon gas, pyrolysis products and a catalyst, which can lead to thermal decomposition of the finished product. Another disadvantage of the known device is the inability to uniformly distribute the powder catalyst evenly over the entire living section of the furnace. This leads to a decrease in the pyrolysis efficiency due to the uneven distribution of the catalyst (a mixture of nickel with 10% aluminum).

Also known is a reactor for producing fibrous carbon structures by catalytic pyrolysis (RF Patent No. 2310023, IPC D01F 9/10, 2007), comprising a casing made of two parts connected by locks, the upper part of the casing being connected to hydrocarbon gas supply and gaseous extraction pipelines pyrolysis products, and heaters are installed in the lower part, and a disk connected to the rotation drive. The catalyst supply unit is also located in the upper part of the reactor, and the finished product collector and the carbon-containing gas supply pipe are located in the lower part, and the reactor is equipped with a precipitating chamber connected to the catalyst supply unit, mounted above the disk connected to the rotation drive and interacting with the stationary scraper, under which the capacity of the finished product is installed, and heaters located above and below the rotating disk, and in the upper part of the casing and precipitating chamber are the product sampling pipes pyrolysis. The catalyst supply unit is made in the form of a dispenser connected via a spray to a gas supply line equipped with a heater. The finished product collector is connected to the inert gas supply line. The rotating disk is equipped with blades mounted on its lower surface. The precipitating chamber is made in the form of an inverted glass with a section in the shape of a sector. The capacity of the finished product is fixed on a cylindrical shell connected to the housing.

The disadvantages of this reactor are the design complexity and the inability to deposit a catalyst layer uniform in thickness on the surface of the disk, which provides nanotubes with a minimum variation in size along the outer diameter, which have higher quality and uniformity of properties. During the synthesis of nanotubes, the inter-cycle period in the periodic mode is excessively long, which leads to an uncontrolled increase in the number of layers, leading to a deterioration in the properties of the synthesized nanotubes and a decrease in productivity.

These shortcomings are due to structural features of the known technical solutions.

According to the set of common features, the reactor according to the patent of the Russian Federation No. 2310023 was selected as a prototype.

The objective of the invention is to provide synthesis of nanotubes with an outer diameter of from 3 to 10 nm.

The technical result is to improve the quality of the synthesized carbon material and increase the productivity of the reactor.

The technical result is achieved by the fact that in the reactor for the synthesis of carbon nanotubes containing a housing equipped with heaters and a metering and catalyst dosing unit made of two parts connected by locks, the upper part of the body connected to the pipelines for supplying carbon-containing gas and sampling gaseous pyrolysis products, and in the lower part a disk connected to the rotation drive is installed in which the dosing and deposition unit of the catalyst is made in the form of a separate deposition apparatus containing bases e, equipped with a disk connected to the rotation drive and a removable cover with a catalyst supply and deposition system on the surface of the container mounted on the disk, and a manipulator for moving the container is installed between the reactor vessel and the deposition apparatus, the reactor body and the deposition apparatus being combined into a single unit by a link between which a manipulator serves to move the container.

The deposition apparatus is connected to a vacuum system and comprises a catalyst dispenser and a sealing device.

The catalyst dispenser is made in the form of a receiving cup and a spray device connected by a compressed air supply line.

The receiving cup is made in the form of a hemisphere mounted on a height-adjustable stand with profiled edges.

The manipulator for moving the container contains a gripping device and a swivel stand with an extension mechanism.

The container is made in the form of a ring with flanged edges.

The implementation of the unit for dispensing and deposition of the catalyst in the form of a separate deposition apparatus containing a base equipped with a disk connected to the rotation drive and a removable cover with a catalyst supply and deposition system on the surface of the container mounted on the disk, and installation of a manipulator between the reactor vessel and the deposition apparatus for moving the container, and the combination of the reactor vessel and the deposition apparatus in a single unit, the connecting link between which is the manipulator for moving the container, provides obtaining multilayer carbon nanotubes with a diameter of from 3 to 10 nm due to the provision of:

- control over the application of the catalyst (a uniform amount per unit area of the container with the same layer thickness);

- creating a uniform temperature field in the catalyst bed by installing the container in the reactor on a rotating disk;

- reducing energy intensity by cooling the reactor only to a temperature of safe catalyst extraction (about 300 ° C) after the reactor is brought to the temperature of catalytic pyrolysis during synthesis;

- reducing the time of the synthesis process, which takes 3-4 minutes;

- reduction of catalyst consumption, due to the exclusion of its deposition on the surfaces of the reactor.

An additional connection of the deposition apparatus with a vacuum system and supplying it with a catalyst dispenser and a sealing device provides a more uniform deposition of the catalyst on the surface of a rotating container. A more uniform catalyst deposition is achieved by reducing the duration of the deposition of the smallest pulverulent particles deposited in a vacuum environment at the same speed as larger particles. It also provides improved quality of the synthesized nanomaterial.

The implementation of the catalyst dispenser in the form of a receiving cup and a spray device connected by a compressed air supply line eliminates the use of inefficient screw feeders, which do not provide uniformity in the supply of small amounts of dusty catalyst with a total weight of about 50 g with high accuracy. In the proposed dispenser, the required dose of the catalyst is measured by weighing and then sprayed with an airflow pulse. This eliminates the wear of the dispensing apparatus and the associated decrease in the accuracy of dispensing.

The execution of the receiving cup in the form of a hemisphere mounted on a height-adjustable rack with profiled edges ensures the simplicity of design and the necessary metering accuracy. Dosage uniformity can be achieved:

- due to the movement of the cup in height;

- due to changes in the momentum of the air stream, which, in turn, may depend on the time of opening of the valves, air pressure in the air line and the amount of vacuum in the cavity of the device.

The implementation of the manipulator for moving the container containing the gripping device and the swivel rack with the extension mechanism provides the container to move the catalyst, move the container to the disk of the reactor desktop and the subsequent unloading of the container after synthesis.

The implementation of the container in the form of a ring with flanged edges provides a more uniform synthesis of nanomaterials by eliminating the central part of the container from the synthesis process. Since the central part of the container is practically motionless during rotation, uniform heating of the catalyst is not ensured. At the same time, the proportion of the central part does not exceed 7-8% of the container surface, and this surface loss is more than compensated by an increase in the quality of nanotubes.

The drawings show:

figure 1 is a General view of the reactor for the synthesis of carbon nanotubes in the open position in the context;

figure 2 is the same as in figure 1 without the upper part of the reactor vessel and the removable cover of the metering and deposition apparatus, top view;

figure 3 is a cross section of the reactor vessel;

figure 4 - the upper part of the manipulator;

figure 5 is a cross section of the metering and deposition apparatus;

Fig.6 is a variant of the design of the cup of the receiving dosing apparatus;

in Fig.7 is the same as in Fig.6, an embodiment of the upper edge;

on Fig - section of the container;

Fig.9 is the same as in Fig.8, a top view.

The list of items indicated in the drawings

1 - the upper part of the body;

2 - lower part of the housing;

3 - manipulator;

4 - the cover of the metering and deposition apparatus;

5 - the base of the metering and precipitation apparatus;

6 - container;

7 - a pipeline for supplying carbon-containing gas;

8 - pipe for the selection of reaction gases;

9 - temperature meter;

10 - gas distribution casing;

11 - rotation drive;

12 - disk;

13 - heaters;

14 - castle;

15 - a vacuum pump;

16 - a locking organ;

17 - a seal;

18 - castle;

19 - funnel;

20 - pipeline;

21 - a locking organ;

22 - receiving cup;

23 - compressed air supply line;

24 - a locking organ;

25 - stand;

26 - position lock;

27 - a conical ring;

28 - emphasis;

29 - latch;

30 - drive;

31 - a horizontal extension hydraulic cylinder;

32 - cylinder vertical movement;

33 - rotation mechanism;

34 - the edges of the container;

35 - pressure gauge.

The carbon nanotube synthesis reactor contains a reactor vessel made of upper part 1 and lower part 2, combined into a single unit by a link in the form of a manipulator 3 with a catalyst metering and deposition apparatus consisting of a removable cover 4 and a base 5. A manipulator 3 is installed in the gap between the lower part of the reactor vessel 2 and the base of the catalyst metering and precipitation apparatus 5 and is designed to move the container 6. The upper part of the reactor vessel 1 is provided with a carbon-containing ha supply pipe 7 behind, the nozzles for the selection of reaction gases 8 and a temperature meter 9. The pipe 7 in the cavity of the upper part of the reactor vessel 1 is connected to the gas distribution casing 10, made in the form of an inverted funnel. In the lower part of the reactor vessel 2, a disk 12 and heaters 13 are connected to the rotation drive 11. The lower 2 and upper 1 parts of the reactor are connected by locks 14.

The base 5 of the catalyst metering and deposition apparatus is equipped with a disk 12 connected to the rotation drive 11 and connected to the vacuum pump 15 through a locking member 16. The removable cover 4 is connected to the base 5 with a sealing device including a seal 17 and locks 18. The removable cover 4 is connected to the system supply and deposition of the catalyst on the surface of the container 6 mounted on the disk 12. The catalyst supply system is made in the form of a funnel 19 connected by a pipe 20 through a locking member 21 with a receiving cup 22 and a feed line of air 23, connected through a locking member 24 to the pipeline 20. On the base 5, a stand 25 with a position lock 26 is installed. On the stand 25, a receiving cup 22 in the form of a hemisphere with shaped edges is mounted as shown in Figs. 6 and 7 A conical ring 27 is made in the lower part of the lid 4, which prevents the settling of catalyst particles outside the container 6. The manipulator 3 for moving the container 6 (Fig. 4) contains a gripping device in the form of a lower stop 28 and a latch 29 connected to the actuator 3 0, and is made in the form of a horizontal extension cylinder 31 and a vertical movement cylinder 32, mounted on the rotation mechanism 33. The container 6 is made in the form of a ring with flanged edges 34. A pressure gauge 35 is installed on the lid 4 of the metering device.

The proposed device operates as follows.

First, the container 6 with the manipulator 3 is installed with the cover 4 on the disk 12 of the base of the metering and deposition apparatus 5. The cover 4 of the metering and deposition apparatus is then mounted on the base 5 and the seal 17 is sealed by tightening the locks 18. A measured amount of a dust-based catalyst is poured into the funnel 19 metal oxides. When the shut-off element 21 is open, the catalyst enters through the pipe 20 into the receiving cup 22 mounted on the stand 25 and fixed by the position lock 26. Then, with the shut-off elements 21 and 24 closed, the vacuum pump 15 is turned on and the shut-off element 16 is opened. After creating the necessary vacuum in the cavity of the apparatus dosing and deposition, which is controlled by the readings of the manovacuum gauge 35, the rotation drive 11 of the disk 12 is turned on and the shut-off element 24 is opened for a split second. At the same time, compressed air from the compressed air supply line 2 3 enters through the pipe 20 into the receiving cup 22 and sprays the catalyst in the volume of the apparatus. Short-term opening of the locking member 24 slightly reduces the vacuum in the cavity of the deposition apparatus, therefore, all the dusty catalyst particles settle almost simultaneously on the upper surface of the rotating container 6. The conical ring 27 prevents the catalyst particles from settling near the walls of the lid 4 outside the container 6. The drive is then switched off. 27 rotation 11 and the vacuum pump 15, the shutoff member 16 is closed and with the help of the shutoff member 21, the pressure in the assembly smoothly equalizes with atmospheric. After depressurization of the apparatus, the locks 18 open and the cover 4 of the metering and precipitation apparatus rises to the upper position, as shown in FIG.

Then, with the manipulator 3, the container 6 is transferred from the disk 12 of the device 5 to the disk 12 of the device 3, for which the horizontal extension cylinder 31 emphasizes 28 to the outer edge 34 of the container 6 and the actuator 30 latch 29 is translated into the lower position. Then, by the combined actions of the vertical displacement hydraulic cylinder 32 and the rotation mechanism 33, the container 6 with the deposited catalyst is moved.

On the lower part 2 of the reactor vessel, the upper part of the vessel 1 is installed and locked by locks 14. The cavity of the reactor vessel is blown with argon or other inert gas to remove atmospheric air from it. For this, inert gas (argon) is supplied through the pipeline 7 under the gas distribution housing 10, which, having a high density, displaces atmospheric air from the reactor cavity through the nozzles for the selection of reaction gases 8. After removing air from the cavity of the reactor vessel, the heating elements 13 located under the disk 12 are turned on and the rotation drive 11 of the disk 12 is turned on. Together with the disk 12, the container 6 mounted on it rotates, thereby ensuring uniformity of heating of the catalyst. Through the pipeline 7 for the supply of carbon-containing gas (methane), the latter enters under the gas distribution cover 10 and moves over the catalyst bed deposited on the surface of the container 6. When methane interacts with the catalyst heated to the pyrolysis temperature (depends on the type of carbon-containing gas and the type of catalyst) on the particle surface The catalyst forms a product in the form of carbon nanotubes. Gas that has not reacted with the catalyst together with gaseous pyrolysis products leaves the space under the gas distribution hood 10 through the annular gap between it and the container 6 into the space between the gas distribution hood 10 and the upper part of the housing 1 and is discharged through the nozzles for the reaction gases 8. The synthesis process in the reactor is controlled using temperature meters 9, which measures the temperature of the catalyst and the temperature of the exhaust gaseous pyrolysis products.

After the synthesis process is completed, the supply of carbon-containing gas through the pipeline 7 is stopped, the heaters 13 are turned off and the reactor cooling (not shown) is turned on and the reactor cavity is purged with an inert gas. When the temperature in the reactor decreases to a safe temperature (approximately below 300 ° C), which excludes the decomposition of the synthesized nanotubes, the cooling is turned off, the inert gas is stopped, and the drive 12 rotates on the disk 12. After opening the locks 14, the upper part of the reactor vessel 1 and container 6 rise up with synthesized nanotubes is removed from the reactor and replaced with another container 6 with a catalyst. After this, the synthesis process is repeated as described above, and the finished product is unloaded from the container 6 after it is cooled to room temperature.

The present invention provides the industrial production of carbon multilayer nanotubes.

Claims (2)

1. The reactor for the synthesis of carbon nanotubes, comprising a housing equipped with heaters and a metering and precipitation apparatus for catalysts and made of two parts connected by locks, the upper part of the housing connected to the pipelines for supplying carbon-containing gas and sampling gaseous pyrolysis products, and connected to the drive in the lower part rotation disk, characterized in that the apparatus for dispensing and deposition of the catalyst contains a base equipped with a disk connected to the rotation drive, and a removable cover with Stem feeding and deposition of the catalyst on the surface of the disk mounted on the container, wherein a gap between the bottom of the reactor vessel and the base unit dosing and deposition of the catalyst the manipulator to move the container. 2. The reactor for the synthesis of carbon nanotubes according to claim 1, characterized in that the deposition apparatus is connected to a vacuum system and contains a catalyst dispenser and a sealing device.

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