On the Development of Fluidized Bed Chemical Vapour Deposition for Large-Scale Carbon Nanotube Synthesis: Influence of Synthesis Temperature

Abstract

The absence of large-scale carbon nanotube synthesis technology (which we define as being of the order of 10 000 tonnes per plant per year) is limiting research and development activities across the sector. We contend that fluidized bed chemical vapour deposition (FBCVD) is the most promising technology for large-scale, low-cost, carbon nanotube synthesis. In this work, multi-walled carbon nanotubes were synthesized on alumina-supported iron, cobalt, or nickel catalysts by catalytic chemical vapour deposition in a 0.5 kg h–1 FBCVD reactor, using ethylene as a carbon source. The carbon nanotube yield was shown to increase with an increase in synthesis temperature from 3.3% at 550°C to 87.6% at 900°C. At higher synthesis temperatures the quality of the nanotubes appeared to improve, although further experiments are required to quantify this within statistically significant limits.

Synthesis of multiwalled carbon nanotubes on Al2O3 supported Ni catalysts in a fluidized‐bed

“…Figure 2 shows that at the starting point of each experiment the measured pressure drop varied between 0 and 2.0 kPa, indicating that this cleaning step was reasonably successful. A review of the literature suggests that stainless steel is most commonly used to construct fluidized‐bed reactors for CNT synthesis 12, 14, 15, 17, 31–33. However, our results suggest that for large‐scale systems an alternative will likely be required.…”

“…Data from the literature further suggests that formation of amorphous carbon as a by‐product during fixed‐bed CNT synthesis is dependent on several independent variables, e.g., catalyst activity,36 carbon source flow rate,37 and the addition of O 2 in the low‐temperature CO/Ar plasma technique 38. Amorphous carbon has also been reported to form on Fe‐based catalysts during fluidized‐bed CVD synthesis 20, 32, 39, 40. However, none of these studies reported the effect of synthesis variables on the amorphous carbon yield.…”

Nanotubes

“…7,8 Fluidised bed CVD methodology using the common CNT producing metals iron, cobalt, and nickel supported on Al 2 O 3 has been used to produce multi-walled carbon nanotubes (MWCNTs) on a scale of 0.5 kg h À1 using ethylene as a carbon source. 9 The fluidised bed CVD method has been reviewed. 10 The effect of catalyst calcination temperature on the uniformity of MWCNT diameter synthesised by the decomposition of methane over the common catalyst combination CoO-MoO/Al 2 O 3 has been studied.…”

Upcycling waste plastics into carbon nanomaterials: A review

“…Additional technologies, such as plasma and microwaves, have been utilized to facilitate the CVD growth. The need for continuous external heating, which consumes large amounts of electric power, is a serious drawback for CVD's use on an industrial scale (e.g., in a fluidized bed reactor) for all but the highest end‐value applications . Another drawback of CVD is that most experiments reported require the injection of H 2 , a highly flammable gas, to promote the reduction conditions needed to synthesize nanotubes.…”