3.1.3. X-ray diffraction (XRD)
As illustrated in Fig. 3, the XRD profiles of catalysts exhibited the
characteristic peaks of crystalline phases, namely CaO, SiO2 and
Ca2SiO4. The CaO and SiO2 (quartz) peaks could be observed for all catalysts
and the Ca2SiO4 crystalline phase could be found at 2 h=31.4° in
catalysts 30% RHA800-800 and 20% RHA800-800. In the lowRHtreatment
temperature (400 °C and 600 °C) therewas only CaOand SiO2 peaks. Besides,
when the RH treatment temperature reached 800 °C, Ca2SiO4
crystalline phase could be found. However, when the CE loading increased
to 50 wt.%, the Ca2SiO4 crystalline phase disappeared.