It can be observed in the XRD patterns of the calcined chicken manure (Fig. 2a) that the intensity and the width of the main characteristic peak of CaO phase (2h = 37.6) become higher and narrower, respectively, with increasing of the calcination temperatures.
According to the Debye-Scherrer’s Equation, these changes in intensity and peak width resulted in the larger crystallite of the
CaO catalyst calcined at higher temperatures