Conceptual design of carbon nanotube processes

Carbon nanotubes, discovered in 1991, are a new form of pure carbon that is perfectly straight tubules with diameter in nanometers, length in microns. The conceptual designs of two processes are described for the industrial-scale production of carbon nanotubes that are based on available laboratory synthesis techniques and purification methods. Two laboratory-scale catalytic chemical vapor deposition reactors were selected for the conceptual design. One (CNT-PFR process) used the high-pressure carbon monoxide disproportionation reaction over iron catalytic particle clusters (HiPCO reactor), and the other (CNT-FBR process) used catalytic disproportionation of carbon monoxide over a silica supported cobalt–molybdenum catalyst (CoMoCAT reactor). Purification of the carbon nanotube product used a multi-step approach: oxidation, acid treatment, filtration and drying. Profitability analysis showed that both process designs were economically feasible. For the CNT-PFR process, the net present value, based on a minimum attractive rate of return of 25% and an economic life of 10 years, was $609 million, the rate of return was 37.4% and the economic price was $38 per kg of carbon nanotube. For the CNT-FBR process, the net present value was $753 million, rate of return was 48.2% and the economic price was $25 per kg of carbon nanotube. The economic price for these processes is an order of magnitude less than the prevalent market price of carbon nanotubes and is comparable to the price of carbon fibers.