The identification of oxygen functional groups in carbonaceous materials by oxygen K-edge XANES Original Research Article

The aim of this paper is to assess the potential of oxygen K-edge X-ray absorption near-edge spectroscopy (XANES) for the identification of oxygen functional groups in carbonaceous materials, with a particular view to the identification of functional groups formed during combustion. A suite of aromatic reference compounds was used to provide “fingerprints” for a range of oxygen functional groups. The results indicate that oxygen K-edge XANES is sufficiently sensitive to functional group type for this application. A set of partially gasified chars was prepared from samples of pure acenaphthylene, Wearmouth coal and Cwmbargoed coal. The oxygen K-edge XANES spectra of these chars clearly show that one can follow the simultaneous loss of oxygen species originating in the carbon and formation of new surface complexes during combustion. It is of particular note that anhydrides and lactones can be readily distinguished using this technique. The mechanistic implications of the results for carbon combustion are discussed.