X-ray Photoelectron Spectroscopic Study of Petroleum Fuel Cokes

The nature of N- and S-containing groups in a set of industrial petroleum fuel cokes calcined in an inert atmosphere at different temperatures (from green coke to 2800°C) has been studied by photoelectron spectroscopy. Although both N 1s and S 2p line profiles were rather complex, several components were identified by applying peak synthesis procedures. In the N 1s spectra, the two main components can be assigned to pyrrolic and pyridinic groups; at higher temperatures, the binding energies (Eb) are shifted to higher values, and a third component is observed at very highEb. Similarly, sulphur displayed mainly a lowEb component associated to thiophenic groups, and two others placed at highEb. In both cases the contribution of these highEb components increased with increasing calcination temperature. The possible relationship between the appearance of these highEb peaks and the presence of oxidized N- and S-groups has been discarded. Then, the existence of N and S atoms replacing C atoms in graphene layers has been proposed as being responsible for such highEb peaks.