The shells were calcined at different temperatures for 4 h and catalyst characterizations were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FT-IR), thermo- gravimetric analysis (TGA)/differential scanning calorimetry (DSC) and Brunauer–Emmett–Teller (BET) surface area measurements .