Synthesis optimization, structural evolution and optical properties of hierarchical nanoporous alumina microspheres prepared by continuous soft chemistry method

In the present work, nanoporous alumina microspheres have been synthesized by sol–gel technique. Acid deficient aluminum nitrate and a mixture of equimolar HMTA-Urea were used as starting materials. The prepared sol then injected as droplets into hot oil column to give spherical shape. After calcinations the samples were characterized by scanning electron microscope, fourier transform infra-red spectroscopy, thermogravimetry–differential thermal analysis, X-ray diffraction and N2 adsorption–desorption isotherms. With respect to the results achieved from the above analyses, it was found that nanoporous alumina microspheres with controllable size and morphology can successfully be produced through sol–gel method.