Single-wall carbon nanotube synthesis by CO disproportionation on nickel-incorporated MCM-41

Both Ni- and Co-MCM-41 may be used for the synthesis of single-wall carbon nanotubes (SWNT). We present a comparative investigation that demonstrates that smaller diameter SWNT with a narrower distribution of diameters are produced using Co-MCM-41. Temperature-programmed reduction and x-ray absorption spectroscopy were used to measure the reducibility and metal cluster growth of Ni- and Co-MCM-41 in He, H₂ and under CO disproportionation reaction. The differences between these two catalysts can be attributed to a greater reducibility of and a greater CO affinity for Ni relative to Co.