Method and apparatus for producing single-wall carbon nanotubes

Abstract

The invention relates to a method for producing single-wall carbon nanotubes. The method of the invention comprises the steps of (a) providing a plasma torch having a plasma tube with a plasma-discharging end; (b) feeding an inert gas through the plasma tube to form a primary plasma; (c) contacting a carbon-containing substance and a metal catalyst with the primary plasma at the plasma-discharging end of the plasma tube, to form a secondary plasma containing atoms or molecules of carbon and atoms of the metal catalyst; and (d) condensing the atoms or molecules of carbon and the atoms of the metal catalyst to form single-wall carbon nanotubes. Alternatively, steps (b) and (c) can be carried out by feeding an inert gas and an inorganic metal catalyst through the plasma tube to form a primary plasma containing atoms of the inorganic metal catalyst and contacting a carbon-containing substance with the primary plasma at the plasma-discharging end of the plasma tube, to form a secondary plasma containing atoms or molecules of carbon and the atoms of metal catalyst. An apparatus for carrying out the method according to the invention is also disclosed.

1 - 36 . (canceled) 
     
     
         37 . A method for producing single-wall carbon nanotubes comprising:
 feeding an inert gas through a plasma torch to form an inert gas plasma;   injecting a carbon-containing substance and a metal catalyst in said inert gas plasma, downstream of said inert gas feed, in order to form a plasma comprising atoms or molecules of carbon and atoms of said metal, wherein at least said carbon-containing substance is injected by means of a feeder disposed within said plasma torch and which extends coaxially thereof;   condensing said atoms or molecules of carbon and said atoms of said metal to form single-wall carbon nanotubes; and   recovering said single-wall carbon nanotubes.   
     
     
         38 . The method of  claim 37 , wherein said atoms or molecules of carbon and said atoms of said metal are condensed through a temperature gradient in order to permit a rapid cooling at a rate of at least 10 5  K/second and obtain a predetermined temperature. 
     
     
         39 . The method of  claim 38 , wherein said condensed atoms or molecules of carbon and said condensed atoms of said metal are maintained at said predetermined temperature in order to obtain single-wall carbon nanotubes. 
     
     
         40 . The method of  claim 39 , wherein said predetermined temperature is comprised between 500 and 1800° C. 
     
     
         41 . The method of  claim 40 , wherein said feeder has an outlet which is disposed inside said plasma torch and downstream of an inert gas inlet of said plasma torch through which said inert gas is fed in said plasma torch to form the inert gas plasma. 
     
     
         42 . The method of  claim 41 , wherein the outlet of said feeder is disposed adjacently to a plasma-discharging end of said plasma torch. 
     
     
         43 . The method of  claim 41 , wherein the metal catalyst comprises at least one metal selected from the group consisting of Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Y, La, Ce, Mn, Li, Pr, Nd, Tb, Dy, Ho, Er, Lu and Gd. 
     
     
         44 . The method of  claim 41 , wherein the carbon-containing substance is a C 1 -C 4  hydrocarbon. 
     
     
         45 . The method of  claim 41 , wherein the carbon-containing substance is a carbon-containing solid. 
     
     
         46 . The method of  claim 41 , further comprising injecting a cooling inert gas downstream of the plasma comprising said atoms or molecules of carbon and said atoms of said metal. 
     
     
         47 . A method for producing single-wall carbon nanotubes comprising:
 feeding an inert gas through a plasma torch to form an inert gas plasma;   injecting a mixture comprising a carbon-containing substance and a metal catalyst in said inert gas plasma, downstream of said inert gas feed, in order to form a plasma comprising atoms or molecules of carbon and atoms of said metal, said mixture being injected by means of a feeder disposed within said plasma torch and which extends coaxially thereof;   condensing said atoms or molecules of carbon and said atoms of said metal through a temperature gradient in order to permit a rapid cooling at a rate of at least 10 5  K/second;   maintaining said condensed atoms or molecules of carbon and said condensed atoms of said metal at a predetermined temperature in order to obtain single-wall carbon nanotubes; and   recovering said single-wall carbon nanotubes.   
     
     
         48 . The method of  claim 47 , wherein said predetermined temperature is comprised between 500 and 1800° C. 
     
     
         49 . The method of  claim 47 , wherein said predetermined temperature is comprised between 900 and 1800° C. 
     
     
         50 . The method of  claim 47 , wherein said predetermined temperature is comprised between 800 and 1300° C. 
     
     
         51 . The method of  claim 49 , wherein said feeder has an outlet which is disposed inside said plasma torch and downstream of the inert gas inlet of said plasma torch through which said inert gas is fed in said plasma torch to form the inert gas plasma. 
     
     
         52 . The method of  claim 51 , wherein the outlet of said feeder is disposed adjacently to a plasma-discharging end of said plasma torch. 
     
     
         53 . The method of  claim 51 , wherein the metal catalyst comprises at least one metal selected from the group consisting of Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Y, La, Ce, Mn, Li, Pr, Nd, Tb, Dy, Ho, Er, Lu and Gd. 
     
     
         54 . The method of  claim 49 , wherein the metal catalyst comprises at least one metal selected from the group consisting of Fe, Co, and Ni. 
     
     
         55 . The method of  claim 49 , wherein the metal catalyst and the carbon-containing substance are used in an atomic ratio metal atoms/carbon atoms of about 0.01 to about 0.06. 
     
     
         56 . The method of  claim 49 , wherein the carbon-containing substance is a C 1 -C 4  hydrocarbon. 
     
     
         57 . The method of  claim 49 , wherein the carbon-containing substance is a carbon-containing solid. 
     
     
         58 . The method of  claim 49 , wherein said produced single-wall carbon nanotubes contain essentially no multi-wall carbon nanotubes. 
     
     
         59 . The method of  claim 49 , wherein said produced single-wall carbon nanotubes contain essentially no fullerenes. 
     
     
         60 . An apparatus for producing single-wall carbon nanotubes, which comprises:
 a plasma torch having a plasma tube for receiving an inert gas so as to form an inert gas plasma, said plasma tube having a plasma-discharging end;   a feeder for injecting a carbon-containing substance and a metal catalyst into said inert gas plasma in order to form a plasma comprising atoms or molecules of carbon and atoms of said metal, said feeder being disposed within said plasma tube, extending coaxially thereof, and being adapted to inject said carbon-containing substance and said metal catalyst into said inert gas plasma downstream of an inert gas inlet of said plasma tube through which said inert gas is fed; and   a condenser for condensing said atoms or molecules of carbon and said atoms of said metal through a temperature gradient in order to permit a rapid cooling at a rate of at least 10 5  K/second, and maintaining said condensed atoms or molecules of carbon and said condensed atoms of said metal at a predetermined temperature in order to obtain single-wall carbon nanotubes.   
     
     
         61 . The apparatus of  claim 60 , wherein said feeder has an outlet which is disposed inside said plasma tube and downstream of said inert gas inlet of said plasma tube. 
     
     
         62 . The apparatus of  claim 61 , wherein the outlet of said feeder is disposed adjacently to said plasma-discharging end.