The present invention discloses the process of supplying
high pressure (e.g., 30 atmospheres) CO that has been preheated (e.g., to about 1000° C.) and a catalyst precursor gas (e.g., Fe(CO)5) in CO that is kept below the catalyst precursor
decomposition temperature to a
mixing zone. In this
mixing zone, the catalyst precursor is rapidly heated to a temperature that results in (1) precursor
decomposition, (2) formation of active catalyst
metal atom clusters of the appropriate size, and (3) favorable growth of SWNTs on the catalyst clusters. Preferably a catalyst cluster
nucleation agency is employed to enable rapid reaction of the catalyst precursor gas to form many small, active catalyst particles instead of a few large, inactive ones. Such
nucleation agencies can include auxiliary
metal precursors that cluster more rapidly than the primary catalyst, or through provision of additional energy inputs (e.g., from a pulsed or
CW laser) directed precisely at the region where cluster formation is desired. Under these conditions SWNTs nucleate and grow according to the Boudouard reaction. The SWNTs thus formed may be recovered directly or passed through a growth and annealing zone maintained at an elevated temperature (e.g., 1000° C.) in which tubes may continue to grow and coalesce into ropes.