Determination of the forms of calcium present in coal chars by Ca K-edge   XANES with Synchrotron Radiation
  This work is concerned with the Ca transformations during the pyrolysis of Ca(OH)2 or CaCO3-added coals. Ca K-edge X-ray absorption near edge structure (XANES) spectroscopy was applied to determine the forms of Ca in chars prepared from the pyrolysis of Ca-added coal. Results showed that Ca(OH)2 and CaSO4 existed in both the Ca(OH)2-added chars and the CaCO3-added chars, while CaS and CaO only existed in the chars prepared from the Ca(OH)2-added coal. Moreover, it was found that carboxyl Ca was formed during pyrolysis for either the Ca(OH)2-added coal or the CaCO3-added coals. 
Lijuan Liu, Huijun Liu, Mingqi Cui, Yongfeng Hu, Lei Zheng, Yidong   Zhao, Chenyan Ma, Shibo Xi, Dongliang Yang, Zhiying Guo...
physics.chem-ph