28. Functional Forms of the Fluorine and Carbon in Fly Ashes Formed in Pulverized Coal Combustion

Abstract

Chemical forms of the fluorine and carbon present in fly ashes formed in pulverized coal combustion have been studied with X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques. Most of the fluorine in the ash samples is enriched on the surface of unburned carbon and exists as covalent C-F bonds. The fluorine content tends to increase with increasing sum of carboxyl and lactone/acid anhydride groups on unburned carbon. HF evolved in the combustion process may react with active carbon sites to form organic fluorine compounds.