Plasmet's Patented Inductively Coupled Plasma Process Can Produce 150 Tons of Carbon Nanomaterial Per Year Per Unit

Plasmet Corporation (Walla Walla, WA) garnered U.S. Patent 7,666,381 for an industrial scale continuous production process for carbon nanomaterials (CNMs) using a high temperature inductively coupled plasma . CNMs can be added to a fuel, to increase its energy density. CNMs can also be added to a polymer to provide improved structural, electrical conductivity, and thermal conductivity properties.

These ICP torch systems can crack sufficient carbonaceous materials to produce as much as 100 to 150 metric tons of CNM per year (based on a single ICP system).  According to inventors Mark Henderson, John Vavruska, Andreas Blutke and Robert Ferguson, producing carbon nanomaterials (CNMs) in a reactor using an inductively coupled plasma (ICP), involves the steps of:

 (a) introducing the ICP into the reactor;

(b) introducing a carbonaceous material into the reactor, such that the ICP heats and reacts with the carbonaceous material to produce free carbon;

(c) introducing a catalyst into the reactor, the catalyst having been selected to enhance the production of CNMs from the free carbon in the reactor;

(d) providing a secondary reaction chamber, the secondary reaction chamber providing additional residence time to promote the growth of longer CNMs;

(e) using supplemental heat to maintain the temperature conditions in the secondary reaction chamber above a threshold value required to facilitate the additional growth of the CNMs; and
(f) introducing additional carbonaceous materials into the secondary reaction chamber to provide carbon to facilitate the additional growth of the CNMs. 

The high-power inductively coupled plasma technology is used for thermal cracking and vaporization of continuously fed carbonaceous materials into elemental carbon,  The reaction with separate and continuously fed metal catalysts takes place inside a gas-phase high-temperature reactor system operating at or slightly below atmospheric pressures.

In one particularly preferred embodiment, in-flight growth of carbon nanomaterials is initiated, continued, and controlled at high flow rates, enabling continuous collection and product removal via gas/solid filtration and separation methods, and/or liquid spray filtration and solid collection methods suitable for producing industrial-scale production quantities,

The reaction chamber can include filtration/separation media which also may include non-catalytic or catalytic metals to simultaneously or separately induce on-substrate synthesis and growth of carbon nanomaterials. The on-substrate grown carbon nanomaterials are produced in secondary chambers that are selectively isolated for periodic removal of the product.

FIG. 2A is a process flow diagram for the in-flight production of CNMs using an ICP, including the sorting of CNMs by size.

FIG. 2B schematically illustrates a differential mobility analyzer that can be employed to sort CNMs by size, as indicated in the process flow diagram of FIG. 2A.

FIG. 9 is a scanning electron microscopy (SEM) image of multi-wall carbon nanotubes grown in-flight and collected on a front face of a process gas heat exchanger

FIGS. 15 are SEM images of carbon nanomaterials grown on stainless steel sheet metal at temperatures of about 1,000.degree. C.