Process for Producing Carbon Nanotubes from Renewable Raw Materials

Abstract

A subject of the present invention is a process for producing carbon nanotubes, the process comprising: a) the synthesis of alcohol(s) by fermentation of at least one vegetable matter and optionally the purification of the product obtained; b) the dehydration of the alcohol or alcohols obtained in a) in order to produce, in a first reactor, a mixture of alkene(s) and water and optionally the purification of the product obtained; c) the introduction, in particular the introduction into a fluidized bed, in a second reactor, of a powdery catalyst at a temperature ranging from 450 to 850° C., this catalyst comprising at least one catalytic metal supported by an inert solid substrate, the grains of catalyst having a d50 of less than 300 μm; d) bringing the alkene produced in b) into contact with the powdery catalyst of stage c), optionally in a fluidized bed, in order to form carbon nanotubes and hydrogen on the surface of said catalyst by catalytic decomposition of said alkene; e) the recovery of the carbon nanotubes produced in d). The invention also relates to nanotubes capable of being obtained according to the abovementioned process, which can be advantageously used in all the known fields of application of carbon nanotubes.

1 . A process for producing carbon nanotubes,comprising
 a) synthesizing alcohol(s) by fermentation of at least one vegetable matter and optionally purifying the product obtained;   b) dehydrating the alcohol or alcohols obtained in a) to produce, in a first reactor, a mixture of alkene(s) and water and optionally purifying the product obtained;   c) introducing, in a second reactor, a powdery catalyst at a temperature ranging from 450 to 850° C., the catalyst comprising at least one catalytic metal supported by an inert solid substrate, the grains of catalyst having a d50 of less than 300 μm;   d) bringing the alkene produced in b) into contact with the powdery catalyst of c), optionally in a fluidized bed, wherein the alkene is mixed with a flow of hydrogen and/or at least part of the water produced during the dehydrating of the alcohol in b), to form carbon nanotubes and hydrogen on the surface of said catalyst by catalytic decomposition of said alkene;   e) recovering the carbon nanotubes produced in d).   
     
     
         2 . A process according to  claim 1  or  24 , wherein c), d) and e) are implemented continuously and simultaneously in the second reactor. 
     
     
         3 . A process according to  claim 1  or  24 , wherein the vegetable matter is selected from beet; sugar cane; cereals such as corn, wheat, barley and sorghum; potatoes;
 biomass; and a source of cellulose. 
 
     
     
         4 . (canceled) 
     
     
         5 . A process according to  claim 1  or  claim 24 , wherein the alcohol is ethanol. 
     
     
         6 . A process according to  claim 1  or  claim 24 , wherein b) is carried out by means of a catalyst based on γ-alumina. 
     
     
         7 . A process according to  claim 1  or  claim 24 , wherein c) is carried out at a temperature of 500° C. to 700° C. 
     
     
         8 . A process according to  claim 24 , wherein the alkene is mixed in d) with a flow of hydrogen and/or at least part of the water produced during the dehydrating of the alcohol in b). 
     
     
         9 . A process according to  claim 1  or  claim 24 , wherein the hydrogen produced in d) is recycled at least in part into the second reactor. 
     
     
         10 . A process according to  claim 1  or  claim 24 , wherein the catalytic metal is iron. 
     
     
         11 . A process according to  claim 1 , wherein the powdery catalyst is produced by impregnating the solid substrate with an aqueous solution of said catalytic metal then calcination of the solid substrate thus impregnated. 
     
     
         12 . A process according to  claim 11  or  claim 24 , wherein the calcination is carried out at a temperature of 200° C. to 400° C. 
     
     
         13 . A process according to  claim 1  or  claim 24 , wherein the d50 of the grains of powdery catalyst is less than 200 μm and preferably greater than 100 μm. 
     
     
         14 - 23 . (canceled) 
     
     
         24 . A process for producing carbon nanotubes, comprising
 a) synthesizing alcohol(s) by fermentation of at least one vegetable matter and optionally purifying the product obtained;   b) dehydrating the alcohol or alcohols obtained in a) to produce, in a first reactor, a mixture of alkene(s) and water and optionally purifying the product obtained;   c) introducing, in a second reactor, a powdery catalyst at a temperature ranging from 450 to 850° C., the catalyst comprising at least one catalytic metal supported by an inert solid substrate, wherein the powdery catalyst is produced by impregnating the solid substrate with an aqueous solution of said catalytic metal then calcination of the solid substrate thus impregnated, and wherein the grains of catalyst having a d50 of less than 300 μm;   d) bringing the alkene produced in b) into contact with the powdery catalyst of c), optionally in a fluidized bed, to form carbon nanotubes and hydrogen on the surface of said catalyst by catalytic decomposition of said alkene;   e) recovering the carbon nanotubes produced in d).   
     
     
         25 . A process according to  claim 1  or  24 , wherein the source of cellulose is corn.