PURPOSE: To safely and inexpensively obtain the subject carbon fibers having a high aspect ratio without a special complicated operation by pyrolyzing a hydrocarbon gas and a catalyst comprising ferric ammonium citrate in a gaseous phase section of a tubular reactor and allowing the carbon fibers to grow in the gaseous phase.
CONSTITUTION: Nitrogen gas is allowed to flow in a tubular reactor 2 through the first conduit tube 7, a powder-dispersing machine 8 and the second conduit tube 10 in the state stopping the feeding of hydrogen gas and a city gas 14, and the tubular reactor 2 is heated with a preliminarily heating means 3 and with a heating means 4. When the temperature in central part of the tubular reactor 2 reaches 110°C, the feeding of the hydrogen gas is started and the supply of the nitrogen gas is stopped. The city gas 14 comprising a hydrocarbon gas is fed into the tubular reactor 2 through an inner tube 13, and simultaneously a catalyst 6 comprising ferric ammonium citrate is stirred with the stirring blade 8B of a powder dispersing machine 8 so as to be accompanied by the reducing flow of the hydrogen gas. The catalyst-containing gas is fed into the tubular reactor 2 through the second conduit tube 10, and then pyrolyzed at the site of the preliminarily heating means 3 to form fine particle nuclei. The fine particle unclei are brought into contact with the hydrocarbon at the site of the heating means 4 to allow the produced carbon fibers to grow in the gaseous phase, followed by collecting the objective carbon fibers 1 in a collection tank 15.
MORIOKI MASAKATSU
ENDO MORINOBU
