Design of a 3-phase AC Plasma Reactor for Solvent-free Fullerene Synthesis
University of New Brunswick
Fullerenes are spherical carbon molecules with unique chemical and physical properties. A particularly distinctive one is that these molecules have a vapor pressure and can directly sublime from a solid phase to vapor. Since their discovery in 1985, hundreds of articles have been published on numerous synthesis methods. However, a process which is environmentally friendly, continuous, scalable and efficient has yet to be achieved. We propose a system for continuous production of solvent-free manufacture of fullerenes using a novel 3-phase thermal plasma reactor. It is scalable, self-stabilizing, low maintenance and efficient. Helium is used as plasma carrier gas with temperatures >5000°C allowing for vaporization of any carbon feedstock. Fullerene yields of up to ~7 wt% at 1 bar absolute were measured, a higher yield than any other known process. Once the fullerenes are produced, they are then separated using a hot gas sublimation at >600°C which allows for solvent-free separation of fullerenes, resulting in an ultrapure product. Economic analysis of a small pilot reactor indicated a net annual profit of 0.75 million CAD at the pilot scale with a capital investment of 2 million CAD. The cost of sublimed fullerene per gram is estimated to be about ~ 7.8 CAD/g which is substantially lower than its current selling price of 24-102 CAD/g. These results validate the efficiency, scalability, economic feasibility and viability of the process. Hence, the route to environmentally friendly production of solvent-free fullerenes on a commercial scale at affordable prices is soon realizable.