The crystallite size of iron oxide and Fe 0 nanoparticles on alpha alumina support was determined using the Scherrer equation. To calculate the crystallite size of Fe2O3, the Scherrer equation was applied for the (211) reflexes at 23° 2θ, the (222) reflexes at 32.5° 2θ, the (510) reflexes at 48.5° 2θ and the (440) reflexes at 54.5° 2θ. The crystallite size of Fe 0 for the reduced iron catalysts was Transmission electron microscopy was used to identify the iron dispersion and the size of the reduced iron nanoparticles (Figure ).