Two methods of forming carbon nano-materials using filtered acetylene gas

A first method of forming carbon nano-materials involves filtering a supply of acetylene gas to remove volatile hydrocarbon gas, mixing the filtered acetylene with an amount of the volatile hydrocarbon gas to provide a gas mixture having a selected proportion of the volatile hydrocarbon gas, feeding the gas mixture into a chamber 2 and performing CVD in the chamber to form the carbon nano-material using the gas mixture. A second method of forming a carbon nano-material involves passing acetylene gas over active carbon to remove a volatile hydrocarbon gas, feeding the filtered acetylene gas into a chamber 2 and performing CVD in the chamber to form the carbon nano-material using the filtered acetylene gas. The nano-material can be carbon nano-tubes grown on a metal-coated substrate 4 and the volatile hydrocarbon can be acetone or dimethylformamide (CH3)2NC(O)H.