It seems, everything is known about carbon. However, there also exists nanofibrous carbon. This particular carbon has recently been often used as a catalyst and electrode material, and also as a splendid adsorbent. Therefore, it can also be used for detrimental impurities refinement, and it can be added to diverse polymers to improve their characteristics.

Nanofibrous carbon is interesting by itself: it consists of carbon fibres of 3 to 500 nm in diameter. These fibres can form " cylinders" (which make almost finished polymeric nanotubes), or a system of cones stowed one into the other at a certain angle to the fibre axis, or simply "wrapping package" – this is driven by the type of applied catalyst and conditions for getting this promising material.

It is interesting to note that the process of obtaining the material is rather simple, therefore the process allows to reclaim various hydrocarbon gases, which in this case become an ideal source of raw materials for production of two very valuable substances - hydrogen and nanofibrous carbon.

The reaction needs a plant which would ensure ideal stirring of the mixture of methane with inert gases (argon, helium or nitrogen) in a microreactor, and nickel catalyst produced under a special method (sol-gel), as a result of which the size of nickel nanoparticles varies from 12 to 60 nm in diameter.

The researchers noticed an interesting phenomenon in the course of the experiment: nanoparticls of the catalyst self-organized. It was ascertained that self-organization is provoked by temperature. For example, the phenomenon was not observed at 500º?, but already at 550º? self-organization took place. When the original size of nanoparticles makes 12 nm, they spontaneously enlarge, but the particles of 60 nm in diameter decrease in size. This interesting puzzle is worth noting and the researchers are going to solve it in the near-term future.

The thickness of nanofibers can be altered by changing the temperature and composition of the gas mixture. For instance, using only pure methane at the temperature of 500º?, the fiber can be as thick as 50-60 nm in diameter, but if the mixture consists of methane and argon in equal shares and the mixture is processed at 600º?, the fibres get thinner - 30 - 40 nm in diameter. The thinnest fibres will be obtained if the methane content is decreased down to 10% - the fibres diameter will make 20 nm.

It turns out that the thickness of bibres can be altered and the form of their packing can be chosen. That opens wide perspectives for creative work, moreover, this is to the benefit of the environment. This is a kind of wasteless industry - unneeded carbohydrates can be used for manufacturing important products. However, it is still to be determined how and why different catalysts impact the type of the carbonic nanofibre packing.
Guzel Afanasieva

ggk@catalysis.nsk.su