A method for producing carbon nanotubes and/or fibers, such as carbon nanotubes, involves sparging a gas (such as carbon dioxide) through a liquid hydrocarbon (such as crude oil) in the presence of an effective amount of metal oxide particles (such as MgO, Al.sub.2O.sub.3, CeO.sub.2, and/or SiO.sub.2 nanoparticles having a size in the range from about 2 nm to about 10 microns, and which may have a bimodal particle size distribution) at a temperature in a range of between about 70 to about 350° C. to produce carbon nanotubes and fibers having a size range of from about 50 nm to about 20 microns.

A method for producing carbon nanotubes and/or fibers, such as carbon nanotubes, involves sparging a gas (such as carbon dioxide) through a liquid hydrocarbon (such as crude oil) in the presence of an effective amount of metal oxide particles (such as MgO, Al.sub.2O.sub.3, CeO.sub.2, and/or SiO.sub.2 nanoparticles having a size in the range from about 2 nm to about 10 microns, and which may have a bimodal particle size distribution) at a temperature in a range of between about 70 to about 350° C. to produce carbon nanotubes and fibers having a size range of from about 50 nm to about 20 microns.

Systems and methods for the formation and/or growth of elongated carbon-based nanostructures on copper-containing substrates, are generally described. Inventive articles comprising elongated carbon-based nanostructures and copper-containing substrates are also described.

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.

The method for producing a carbon nanotube yarn includes preparing a vertically-aligned carbon nanotube that is disposed on a substrate and is aligned vertically to the substrate; preparing a rotating body having a groove on a circumferential face; drawing a plurality of carbon nanotubes from the vertically-aligned carbon nanotube continuously and linearly to prepare a carbon nanotube single yarn, and arranging the plurality of carbon nanotube single yarns in parallel to prepare a carbon nanotube web; winding the carbon nanotube web around the circumferential face of the rotating body so as to fit in the groove; and drawing the carbon nanotube web from the rotating body.

The method for producing a carbon nanotube yarn includes preparing a vertically-aligned carbon nanotube that is disposed on a substrate and is aligned vertically to the substrate; preparing a rotating body having a groove on a circumferential face; drawing a plurality of carbon nanotubes from the vertically-aligned carbon nanotube continuously and linearly to prepare a carbon nanotube single yarn, and arranging the plurality of carbon nanotube single yarns in parallel to prepare a carbon nanotube web; winding the carbon nanotube web around the circumferential face of the rotating body so as to fit in the groove; and drawing the carbon nanotube web from the rotating body.

A method and precursor for making carbon fibers and the like comprising carbon black modified with at least one cyclic compound promoter. A source of the carbon black may be recycled materials such as recycled tires or recycled plastics. The carbon black is modified by attaching at least one cyclic compound promoter to the outer periphery of the carbon black.

A low carbon footprint material is used to decrease the carbon dioxide emission for production of a high carbon footprint substance. A method of forming composite materials comprises providing a first high carbon footprint substance; providing a carbon nanomaterial produced with a carbon-footprint of less than 10 unit weight of carbon dioxide (CO.sub.2) emission during production of 1 unit weight of the carbon nanomaterial; and forming a composite comprising the high carbon footprint substance and from 0.001 wt % to 25 wt % of the carbon nanomaterial, wherein the carbon nanomaterial is homogeneously dispersed in the composite to reduce the carbon dioxide emission for producing the composite material relative to the high carbon footprint substance.

A nanofiber yarn placement system includes a yarn dispenser assembly, and a placement assembly. The placement assembly includes a compliant flange, and a guide connected to the compliant flange. The guide defining a channel. The channel includes at least one internal surface and at least one corner defined by the at least one internal surface.

A supported catalyst comprises: a support that is particulate; and a composite layer laminate formed outside the support and including two or more composite layers, wherein each of the composite layers includes a catalyst portion containing a catalyst and a metal compound portion containing a metal compound, the support contains 10 mass % or more of each of Al and Si, and a volume-average particle diameter of the support is 50 μm or more and 400 μm or less.