By using CNF excellent in dispersibility, conductivity, and crystallinity, a conductive polymer material having high conductivity even with a low CNF content and a shaped article thereof and a conductive polymer material with a less CNF content for same conductivity and a shaped article thereof are provided. A conductive polymer material with high conductivity is produced by using carbon nanofiber with a median diameter D50 value from 0.1 to 8 μm, powder resistivity of 0.03 Ωcm or less measured under a load of 9.8 MPa, and D/G from 0.5 to 1.3.

A manufacturing method of carbon nanofibers at a high activity is provided. Further, carbon nanofibers produced by the manufacturing method and being excellent in electric conductivity, crystallinity and dispersibility is provided. By a manufacturing method of carbon nanofibers in which an active species including cobalt as a chief component is employed as a catalyst and carbon monoxide is used as a carbon source, wherein said catalyst has 3 to 150 mass % of said active species carried on a carrier composed of a magnesium-containing oxide having a specific surface area of 0.01 to 5 m.sup.2/g, and a reaction temperature, partial pressure of carbon monoxide and a flow rate of raw material gas is controlled, CNFs that are excellent in electric conductivity, crystallinity and dispersibility can be manufactured at high activity, so that carbon nanofibers that is excellent in electric conductivity, crystallinity and dispersibility is obtained.

An object of the present invention is to provide a method for a carbon nanofiber composite, which can obtain a carbon nanofiber composite with high productivity and high activity, and which does not require removal of fluidizing materials or dispersing materials. The present invention also provides a carbon nanofiber composite having improved dispersibility. The method for producing the carbon nanofiber composite includes bringing at least one catalyst and at least one particulate carbon material into contact with at least one gas containing at least one gaseous carbon-containing compound while mechanically stirring the catalyst and the particulate carbon material in a reactor. The carbon nanofiber composite includes carbon nanofibers and at least one particulate carbon material, wherein the particulate carbon material has 70% by volume or more of particles with a particle diameter of 1 μm or less, and/or a median diameter D50 by volume of 1 μm or less.

A method for a carbon nanofiber composite, which can obtain a carbon nanofiber composite with high productivity and high activity, and which does not require removal of fluidizing materials or dispersing materials, provides a carbon nanofiber composite having improved dispersibility. The method for producing the carbon nanofiber composite includes bringing at least one catalyst and at least one particulate carbon material into contact with at least one gas containing at least one gaseous carbon-containing compound while mechanically stirring the catalyst and the particulate carbon material in a reactor. The carbon nanofiber composite includes carbon nanofibers and at least one particulate carbon material, wherein the particulate carbon material has 70% by volume or more of particles with a particle diameter of 1 μm or less, and/or a median diameter D50 by volume of 1 μm or less.

By using CNF excellent in dispersibility, conductivity, and crystallinity, a conductive polymer material having high conductivity even with a low CNF content and a shaped article thereof and a conductive polymer material with a less CNF content for same conductivity and a shaped article thereof are provided. A conductive polymer material with high conductivity is produced by using carbon nanofiber with a median diameter D50 value from 0.1 to 8 m, powder resistivity of 0.03 cm or less measured under a load of 9.8 MPa, and D/G from 0.5 to 1.3.

An object of the present invention is to provide a method for a carbon nanofiber composite, which can obtain a carbon nanofiber composite with high productivity and high activity, and which does not require removal of fluidizing materials or dispersing materials. The present invention also provides a carbon nanofiber composite having improved dispersibility. The method for producing the carbon nanofiber composite includes bringing at least one catalyst and at least one particulate carbon material into contact with at least one gas containing at least one gaseous carbon-containing compound while mechanically stirring the catalyst and the particulate carbon material in a reactor. The carbon nanofiber composite includes carbon nanofibers and at least one particulate carbon material, wherein the particulate carbon material has 70% by volume or more of particles with a particle diameter of 1 m or less, and/or a median diameter D50 by volume of 1 m or less.

Provided is a method for producing carbon nanotibers having excellent conductivity, crystallinity and dispersibility. A method for producing carbon nanofibers, which uses an activated species mainly composed of cobalt as a catalyst, while using carbon monoxide as a carbon source. The catalyst is obtained by having a carrier, which is composed of an oxide having a specific surface area of 0.01-5 m.sup.2/g and containing magnesium, support 3-90% by mass of the activated species. By controlling the reaction temperature, the carbon monoxide partial pressure and the gas flow rate of the carbon monoxide, CNF having more excellent conductivity, crystallinity and dispersibility can be produced, thereby obtaining carbon nanofibers having excellent conductivity, crystallinity and dispersibility.

A method for a carbon nanofiber composite, which can obtain a carbon nanofiber composite with high productivity and high activity, and which does not require removal of fluidizing materials or dispersing materials, provides a carbon nanofiber composite having improved dispersibility. The method for producing the carbon nanofiber composite includes bringing at least one catalyst and at least one particulate carbon material into contact with at least one gas containing at least one gaseous carbon-containing compound while mechanically stirring the catalyst and the particulate carbon material in a reactor. The carbon nanofiber composite includes carbon nanofibers and at least one particulate carbon material, wherein the particulate carbon material has 70% by volume or more of particles with a particle diameter of 1 m or less, and/or a median diameter D50 by volume of 1 m or less.

A reaction assembly has an elongate vessel defining a reaction chamber. Planar supports within the reaction chamber have surfaces for supporting a solid catalyst. The planar supports are mounted transversely to an elongate axis of the vessel, forming a series of spaced-apart barriers. A conduit introduces gas through openings between successive barriers such that gas flow through the conduit causes gas to flow along the support surfaces. With selection of an appropriate metal nanoparticle catalyst that may be seeded on the support surfaces. the reaction assembly may be used to produce carbon nanofibers from carbon monoxide and hydrogen, wherein the nanofibers may be subsequently removed via injection of a fluid.

Systems and a method for forming carbon nanotubes are described. A method includes forming carbon nanotubes in a reactor, using a Bosch reaction. The carbon nanotubes are separated from a reactor effluent to form a waste gas stream. The feed gas, a dry waste gas stream, or both, are heated with waste heat from the waste gas stream. The waste gas stream is chilled in an ambient temperature heat exchanger to condense water vapor, forming a dry waste gas stream.