Structural Change of Calcium Silicate, a New Type of Desulfurization Material, Studied by Si K Edge XAFS

CaSiO, was found to be a material effective for deSOx in the presence of NO. The material is promising for the solution of environmental problems of exhaust gas from power station. SO2 was removed as CaSO,, involving oxidation of sulfur, accompanied by reduction of NO. After use as a deSOx reagent, it is confirmed that calcium ions become sulfate form but it has been difficult to examine what form silicon atoms are stanilized as. @ silicon in metasilicate chain may be broken by absorption of SOX and it is expected that it changes to Q4 silicon as a silica. However, there has been no direct evidence. In the present work, we recorded Si Kedge XAFS of CaSiO, before and after use at UVSOR, Okazaki, Japan. The XANES spectra suggested the formation of @ silicon, possibly, forming so-called silica.