Preparation of nano-sized α-Al2O3 from oil shale ash

Oil shale ash (OSA), the residue of oil shale semi-coke roasting, was used as a raw material to synthesize nano-sized α-Al2O3. Ultrasonic oscillation pretreatment followed by azeotropic distillation was employed for reducing the particle size of α-Al2O3. The structural characterization at molecular and nanometer scales was performed using X-ray diffraction (XRD), transmission electron microscopy (TEM), respectively. The interaction between alumina and n-butanol was characterized by Fourier transform infrared spectroscopy (FT-IR). The results revealed that the crystalline phase of alumina nanoparticles was regular and the well dispersed alumina nanoparticles had a diameter of 50–80 nm. In addition, the significant factors including injection rate of carbon oxide (CO2), ultrasonic oscillations, azeotropic distillation and surfactant were investigated with respect to their effects on the size of the alumina particles.