Can oil shales be used to produce fullerenes?

Abstract

Laser ablation Fourier transform ion cyclotron resonance mass spectrometry, FTIR and solid state 13C NMR have been used to study bitumen-free raw Kukersite, Torbanite and Göynük Oil Shale in an attempt to observe whether these materials might be used as fullerene precursors. Solid state 13C NMR and FTIR spectra and elemental analyses indicated that, upon pyrolysis at 400°C under a helium flow, the above oil shales undergo an efficient loss of alkyl groups and aromatization, affording mainly polycyclic, aromatic, insoluble residues. Species that are easily converted to fullerenes are thus obtained and such residues can produce fullerenes, via laser ablation, at much lower laser powers than graphite. In sharp contrast, the 300°C residues are not suitable fullerene precursors. The minimal power required for fullerene production with 400°C residues significantly increases from Kukersite to Torbanite and to Göynük Oil Shale. The latter feature is associated with some decrease in aromatization efficiency, upon 400°C pyrolysis, from Kukersite to Göynük Oil Shale. This study confirms the general usefulness, for fullerene production by laser pyrolysis, of the insoluble residues obtained at 400°C from raw oil shales composed of Type I kerogens. Copyright