IN-SITU X-RAY STUDIES OF CUO AL2O3 SORBENTS REACTING WITH COAL FLUE-GAS/

X-ray absorption fine structure (XAFS) spectroscopy was used to study the local structure around the Cu ion in CuO/Al2O3 sorbents in situ. T he measurements were performed between room temperature and 400-degree s-C in a reaction cell with and without coal flue gas flow. Similar me asurements were carried out using standard copper compounds. No signif icant changes were observed in the XAFS spectra of the sorbents when t he measurements were performed in the presence of nitrogen. In contras t, new near-edge features appeared in the spectra of the sorbents in t he presence of flue gas. A strong peak appeared at an energy character istic of monovalent copper. No significant changes were detected in th e Cu-O nearest-neighbour distance for any of the samples. The near-edg e spectra were analysed to obtain the partial ratios of monovalent to divalent copper as a function of temperature and metal loading of the sorbents. The standard compounds showed no evidence of a reaction with the flue gas that might suggest the presence of monovalent copper. Th e present results indicate the complex nature of the reactions taking place on the Cu ion site during removal of SO2. The dominant phase aft er reaction gives the characteristic parameters of copper sulfates.