X-ray Absorption Spectroscopic Investigation of Trace Vanadium Sites in Coal.

X-ray absorption spectroscopy was used to probe the chemical and structural environment of vanadium in coal. It was found that vanadium exists in at least two environments, in both of which it was coordinated to oxygens. There was no evidence of vanadium in nitrogen (porphyrin) or sulfide environments. It was also found that the vanadium environments in the raw coal did not survive unchanged in a liquefaction process. These findings have implications for coal cleaning processes and for trace element release into the liquefaction process stream.