Equipment for synthesizing multi-wall carbon nanotubes by water protection method

[0010] Below in conjunction with accompanying drawing, further illustrate working principle of the present invention and specific embodiment:

[0011] The present invention mainly comprises a water container 1, an anode rod 3 placed in water, a cathode rod 5 and a protective cover placed on the electrodes. Inside; the catalyst 4 is filled in the anode rod, the liquid in the container 1 is deionized water 2, and the cathode and anode are placed vertically, or horizontally or obliquely. like figure 2 As shown, this embodiment adopts DC welding power supply (30V, 50A), anode rod 3 is connected to the positive pole of the power supply, cathode rod 5 is connected to the negative pole of the power supply, and 1 is a plexiglass water container (long 200mm, wide 200mm, high 200mm), anode carbon The diameter of the rod is 6mm, the length is about 50mm, there are small holes drilled on it, the diameter is 3.2mm, the depth is 20-30mm, and the catalyst (Ni, Y 2 o 3 , graphite powder mixture, the atomic ratio of Ni:Y is 4.2:1, the graphite powder accounts for 95% of the total weight of the mixture), the cathode carbon rod has a diameter of 16mm and a length of about 100mm, 6 is a stainless steel protective cover with a diameter of 100mm and a height of 140mm , the wall thickness is 2mm. Before arcing, fill the inner cavity of the protective cover with deionized water and immerse it under the liquid surface of the container, align and contact the cathode and anode, then turn on the power, and pull the two electrodes slightly apart to start the arc. At this time, the protection A part of water in the cover will react with carbon to generate gas (mainly hydrogen and carbon monoxide), so that the rest of the water will be gradually discharged from the protective cover, forming a gas reaction chamber 9 in the protective cover; in the following process, due to The water vapor produced by the heating of the water surface under the reaction chamber and a small part of carbon continue to react to generate gas, which can prevent water from entering the protective cover, and most of the remaining carbon evaporated from the anode is deposited on the cathode to form carbon nanotubes 7 . Keeping the continuous feeding of the anode can make the arc between the two electrodes stable and the reaction proceed continuously.

[0012] And when there is no protective cover to directly use electrodes to arc in water (that is, arc method in water), the quality and output of carbon nanotubes are very low. if still using figure 2 With the apparatus and parameters shown, without the protective cover 6, the carbon nanotubes produced are less than 10 mg per minute, and the purity is less than 20%. This may be because when there is no protective cover, the electrode is in direct contact with water, and the carbon reacted with water is greatly increased. In addition, because a large number of bubbles are generated around the arc area, the arc is unstable, and the stability of the arc is a very important factor affecting the quality of carbon nanotubes. When the protective cover is added, the electrode only reacts with a small amount of water vapor to reduce the carbon consumption. At the same time, because the air bubbles escape from the port of the protective cover away from the arc area, it will not affect the stability of the arc, so that The yield and purity of carbon nanotubes are greatly improved.