For comparison, the Ac–CaO and NO3–CaO (treated with ethanol at
100 °C) were also synthesized and their activity was evaluated in comparison
to that of commercial CaO. The XRD patterns of the Ac–CaO,
NO3–CaO and C–CaO catalysts are shown in Fig. 4. The main crystalline
phases are ascribable to CaO and Ca(OH)2, as for the M-CaO catalysts.