Cobalt compounds tetrahedral clusters

Co-MCM-41 catalyst in H2 at temperatures up to 993 K. It is this intermediate species that preserves the tetrahedral environment in the silica framework and provides the resistance to complete reduction to the metal in the presence of H2. The Co(II) species is resistant to reduction in pure CO the intermediate Co(I) species is more reactive in CO, likely forming cobalt carbonyl-like compounds with high mobility in the MCM-41. These mobile species are the precursors of the metal clusters that grow the carbon nanotubes. Controlling the rates of each step of this two-step reduction process is a key to controlling the sizes of the cobalt metal clusters formed in the cobalt MCM-41 catalysts. 

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