The surface morphology of the catalyst was studied by SEM. Fig. 3(a) depicts the SEM image of fresh catalyst. At the magnificationof 2000, the calcined catalyst showed stone-like particles with irregular size. This result was consistent with previous work on different types of shells [17–23]. The calcined obtuse horn shell showed similar morphology with the calcined golden apple snail shell, meretrix venus shell and calcined eggshell. Aggregates with larger sizes were also observed