Fullerene formation in acetylene/oxygen/argon/chlorine flames Original Research Article

The impact of Cl2 addition on the fullerene formation in acetylene/oxygen/argon flat flames burning at low pressure was investigated. The quantities of C60 and C70 in the soot were determined by HPLC after extraction with toluene. Negative ion mass spectra were measured using chemical ionization by means of a CH4/N2O mixture. The chlorine containing species were identified by means of a precursor ion mass spectrum. The addition of 25% of Cl2 led to a dramatic increase of fullerene formation; soot containing 7.7% of (C60 + C70) was deposited in the combustion chamber. The mass spectra showed signals at the masses of C10H2, C11H8 and C12H10 for soot formed in flames with and without chlorine addition while peaks corresponding to the polycyclic aromatic hydrocarbons (PAH) C18H10, C22H12 and C24H12 could be observed only without chlorine addition. A positive role of thermally and photochemically unstable chlorinated intermediate species is suggested for the increase of fullerene formation.