CN1528662A

CN1528662A - Process method for preparing nano carbon powder

Info

Publication number: CN1528662A
Application number: CNA200310100468XA
Authority: CN
Inventors: 丰郑; 郑丰; 王立众; 李勇; 王世凡
Original assignee: Zhongchao Nano-Meter Industry Co Ltd Hailongjiang
Current assignee: Zhongchao Nano-Meter Industry Co Ltd Hailongjiang
Priority date: 2003-10-17
Filing date: 2003-10-17
Publication date: 2004-09-15

Abstract

The invention is a nano carbon powder preparing method, using high-power laser as reaction energy, C2H2 as reacting gas, and C2H4 as photosensitive gas, and its character lies in the following step: (1) focusing the laser by adjusting the light path in the reaction chamber; (2) vacuumizing the system and charging nitrogen gas; (3) adjusting the spray nozzle and window in the reaction chamber to protect the nitrogen gas, starting vacuum pump to make the system in a dynamic balance; (4) proportionally mixing the reacting and photosensitive gases; (5) making the reacting mixed gas enter the reaction chamber and intersect the laser; (6) making the carbon ion quickly condense into nucleus, and obtaining the nano carbon powder; (7) quickly cooling; (8) degasifing; (9) collecting the powder and packaging. The nano carbon powder has high purity, fine particle and uniform particle size. Its technical condition can be controlled.

Description

Process for preparing nano carbon powder

The technical field is as follows:

the invention belongs to the technical field of nano-powder production, and particularly relates to a method for producing nano-carbon powder by using a laser method

As a new material, the nano carbon powder can be widely applied to the fields of rubber, pigment, printing ink, electronics, composite materials and the like, and has wide application prospect and great market potential.

(II) background of the invention:

at present, carbon black products sold in the market mainly use fine powder produced by incomplete combustion of carbon-containing raw materials (mostly petroleum), and the main production methods include four methods, namely a furnace method, a tank method, a thermal method and a lamp method, and the particle size of the carbon powder produced by the methods is large.

The laser method is one of the most advanced methods for producing nano-powder in the world, and can produce nano-silicon carbide, silicon nitride, silicon carbonitride composite powder, silicon powder, alumina powder and the like, but the preparation of the nano-carbon powder by adopting the laser method is reported.

(III) the invention content:

the invention aims to provide a method for preparing nano carbon powder, which has the advantages of high purity, superfine property, uniform particle size, no hard agglomeration and simple process.

The method uses continuous irradiation of high-power laser as reaction energy to lead the photosensitive gas C to be₂H₄With a reaction gas C₂H₂(or methyl alkyl and ethane) enter a reaction chamber filled with inert gas in sequence, and carry out gas phase pyrolysis reaction under laser irradiation, and C is utilized₂H₄The intense absorption of carbon dioxide laser light of wavelength 10.6 μm by the gas and the breaking of C ═ C double chains and C-H chains, i.e.

At the same time due to C₂H₄The C ions and hydrogen ions generated by decomposition have high activity, and they are reactive with C₂H₂Molecular collision generates energy transfer and homogenization, the temperature of a reaction system rises sharply along with the aggravation of the molecular collision, and finally C₂H₂Also reach an activated state, in a very short moment, the C ≡ C chain andC-H chain is broken, the generated particles rapidly leave the reaction zone under the action of inertia of airflow and coaxial nitrogen to be condensed, nucleated and grown, and the particles are rapidly cooled to generate simple substance carbon and hydrogen, namely:

then the mixture enters a settling and filtering system, hydrogen and incompletely reacted gas generated in the settling and filtering process are evacuated by a water ring pump along with nitrogen, and a product enters a powder collecting and packaging system through a degassing device.

In summary, the method of the present invention can be summarized as the following steps:

(1) adjusting the optical path of the reaction chamber to focus the laser beam

(2) The system is vacuumized and filled with nitrogen

(3) Adjusting the protective nitrogen gas of the nozzle and the window of the reaction chamber, and starting the vacuum pump to make the air pressure of the system in dynamic balance

(4) Mixing the reaction gas and the photosensitive gas in proportion

(5) The reaction mixture gas enters the reaction chamber and intersects with the laser

(6) Formation of carbon ions by rapid condensation nucleation

(7) Rapid cooling

(8) Degassing of gases

(9) Collecting and packaging powder

The invention has the beneficial effects that:

1. compared with other methods, the nano particles prepared by the method have fine and uniform particle size and d_MAX/d_AVE＜2；d_AVE≤26.5nm

2. The product prepared by the method has high purity (the content of the main phase is more than or equal to 98 percent), and is regular in shape and spherical.

3. In the process of synthesizing the nano carbon powder by using the method, the gas flow speed and the gas flow are controllable; the reaction pressure and temperature can be adjusted, so that the whole process is in an adjustable and controlled state.

4. The whole production process is carried out under the protection of flowing nitrogen in an oxygen isolation state, so that the problem of oxygen content of the nano-scale carbon powder is effectively prevented.

(IV) description of the drawings: FIG. 1 is a block diagram of a system used in the method of the present invention

(V) detailed description of the preferred embodiments

The method of the present invention is described in detail below with reference to FIG. 1

Preparation before production

Cleaning the production system, and cleaning the whole system of the reaction chamber and the powder transmission, filtration, storage and packaging without impurities.

Adjusting the light path of the reaction chamber, enabling the laser beam to be focused at the center of the reaction chamber through a focusing lens and a reflector, wherein the laser power is 1500-&ltwbr&gt 2000W, and the spot size is not more than 18 multiplied by 16mm at the position 2-8mm right below the reaction nozzle.

The whole production system is vacuumized to ensure that the vacuum degree of the system is less than 6Pa, and then high-purity protective nitrogen is filled into the system until the normal pressure is slightly higher.

Adjusting the nozzle protection nitrogen of the reaction chamber and the window protection nitrogen of the reaction chamber, starting the vacuum pump, controlling the pumping rate by adjusting the opening of the adjusting valve, and enabling the pressure of the whole system to be in a dynamic balance state (the reaction pressure is 50-110KPa)

Thirdly, controlling the flow of photosensitive gas (ethylene) and the flow of reaction gas (acetylene, ethane, methane and the like) through a mass flow meter, wherein the photosensitive gas flow rate is as follows: 0.14-4.12L/min, reaction gas flow: 1.0-10.0L/min, and mixing in a gas mixing tank.

And fourthly, the reaction mixed gas enters the reaction chamber at a certain flow rate through a reaction gas nozzle (the diameter of the reaction nozzle is 6-8mm), the reaction mixed gas is intersected with the vertically injected laser beam focused by the focusing lens, the photosensitive gas ethylene absorbs the energy of the carbon dioxide laser with the diameter of 10.6 microns, so that C ═ C double bonds and C-H bonds are broken, carbon ions and hydrogen ions are generated, the carbon ions and the hydrogen ions collide with the reaction gas molecules, energy transfer and homogenization are carried out, the molecular bonds of the reaction gas are broken, the carbon ions and the hydrogen ions are generated, the temperature of the reaction system is rapidly increased, and high-temperature flame is generated. Flame temperature: 1350-.

And fifthly, the generated carbon ions are rapidly condensed to form nuclei and grow, and are rapidly separated from the reaction zone under the inertia effect of the airflow and the action of coaxial protection nitrogen, and are rapidly cooled to form carbon nanoparticles and hydrogen.

Sixthly, under the action of an air pump, under the clamping of protective nitrogen, the carbon nano particles are cooled by a powder conveying pipe and then enter a settling tank, a part of carbon nano powder is settled in the tank, the rest of carbon nano powder is respectively retained in a primary filtering tank and a secondary filtering tank after primary filtering and secondary filtering, and residual gas of reaction is evacuated by a vacuum pump and a gas-liquid separation tank.

And seventhly, vacuumizing the degassing tank to negative pressure, opening the electric valve 7, the valve 8 and the valve 10 to enable the nano carbon powder stored in the settling tank, the primary filtering tank and the secondary filtering tank to enter the degassing tank under the action of pressure difference, closing the valve 7, the valve 8 and the valve 10, and filling high-purity nitrogen into the degassing tank to normal pressure.

Eighthly, pumping air from the glove box to a negative pressure, opening ball valves 11 and 12 to enable the nano carbon powder in the degassing tank to enter the glove box along with high-purity nitrogen under the action of pressure difference, settling, collecting, bottling, metering and sealing.

Claims

1. A process for preparing nano carbon powder features use of high-power laser as reaction energy and C₂H₂As a reaction gas, with C₂H₄Is photosensitive gas and is characterized by comprising the following process flows:

(1) adjusting the optical path of the reaction chamber to focus the laser beam;

(2) vacuumizing the system and filling nitrogen;

(3) adjusting the protective nitrogen of a nozzle and a window of the reaction chamber, and starting a vacuum pump to ensure that the air pressure of the system is in dynamic balance;

(4) mixing the reaction gas and the photosensitive gas in proportion;

(5) the reaction mixed gas enters the reaction chamber and intersects with the laser;

(6) carbon ions are rapidly condensed and nucleated to generate;

(7) rapidly cooling;

(8) degassing;

(9) and (6) collecting and packaging the powder.

2. A process for preparing nano carbon powder as claimed in claim 1, wherein said reaction gas is methane or ethane.

3. The process for preparing nano carbon powder as claimed in claim 1, wherein the laser power is 1500-.

4. The process for preparing nano carbon powder according to claim 1, wherein the laser beam focusing point is located 2-8mm directly below the reaction nozzle, and the spot size is not more than 18 x 16 mm.

5. A process for preparing nano carbon powder as claimed in claim 1, wherein the flow rate of said reaction gas is 1.0-10.0L/min, and the flow rate of said photosensitive gas is 0.14-4.12L/min.

6. The process for preparing nano carbon powder according to claim 1, wherein the reaction pressure of the reaction system is 50-110 Kpa.

7. A process for preparing nano carbon powder according to claim 1, wherein the diameter of the reaction nozzle is 6-8 mm.