Generation of Higher Fullerenes in Flames

Abstract

The presence of fullerenes up to C 116 was observed in condensable material from a benzene/oxygen flame. The flame material was Soxhlet-extracted with toluene for 363 h, fractionationed by means of a silica-based semipreparative HPLC column, and analyzed by HPLC coupled to a mass spectrometer via a heated nebulizer interface using a 2-(1-pyrenyl)ethylsilica stationary phase. UV-vis spectra were measured for C 60 , C 60 O, C 60 ‚CH 4 , C 70 , C 70 O, C 76 , C 78 , C 80 , C 84 , a C 84 adduct, C 86 , C 88 , C 90 , C 92 , C 94 , C 96 , C 98 , C 100 , C 102 , and C 108 . Isomers could be discerned for C 78 , C 90 , and C 94 . A calibration using external standards was performed for C 60 , C 70 , C 76 , C 78 , and C 84 . For all other species the relative abundances were estimated based on HPLC peak integration results. Electric arc soot was extracted under similar conditions and the quantification of fullerenes compared to the data obtained with flame-generated condensable material. Except for C 60 and C 76 , the abundances were significantly higher in the case of flame-generated condensable material. Also, striking differences between the two fullerene production methods are seen in the relative abundances of C 78 isomers. Considering the present results and the ease with which the experimental setup could be scaled up, flame-generated condensable material represents an excellent starting material for the preparative isolation of higher fullerenes.

Fullerenes and Soot Formation— New Pathways to Large Particles in Flames

“…[50] The obtained amounts of C 60 :C 70 :C 76 :C 78 :C 84 corresponded to 100:100:4:3:6, while those of C 84 :C 86 :C 90 :C 92 :C 94 :C 96 followed a ratio of 100:0.5:5:0.5:1.25:1.…”

Soot Formation in Combustion Processes (Review)

“…Later, macroscopic quantities of various fullerenes, not only such as C 60 and C 70 [21,23] but also larger species up to C 116 , were extracted by solvents from the soot formed in low-pressure premixed laminar benzene flames [24].…”

“…Finally, the flames suitable for the synthesis of macroscopic quantities of fullerenes [23,24] are characterized by higher values of C/O than the flames from which molecular-beam sampling can be performed [30,38]. The processes of soot and fullerene formation along the flame axis at high C/O ratios, where substantial quantities of fullerenes are produced, are apparently similar, and, hence, the contribution of the condensedphase formation pathways cannot be ruled out.…”

Synthesis of fullerenes and fullerenic nanostructures in a low-pressure benzene/oxygen diffusion flame

“…They were first detected in flames in ionic form by the Homann group [8,9] and later isolated in macroscopic quantities by Howard et al [10][11][12]. Higher fullerenes [13], derivatives containing hydrogen and oxygen [14,15], and fullerenic nanostructures [4,5,16] and soot [6,7] have also been detected in premixed flames.…”