Simple synthesis of Al2O3 sphere composite from hybrid process with improved thermal stability for catalytic applications

• Published in: Materials chemistry and physics Vol. 160; pp. 119 - 130
• Main Authors: Santos, Regina C.R., Pinheiro, Antônio N., Leite, Edson R., Freire, Valder N., Longhinotti, Elisane, Valentini, Antoninho
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-06-2015
• Subjects: Heat treatment; Oxides; Sintering; Surface properties; Surface properties; Oxides; Heat treatment; Sintering
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2015.04.014

Aluminium oxide spheres were synthesized by the hybrid process applying the biopolymer chitosan. After the calcination process the porous spheres were characterized by Chemical elemental analysis (XRF), X-ray diffraction (XRD), Scanning electron microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), N2 adsorption–desorption isotherms, infrared spectroscopy (IR), and CO2 temperature programmed desorption (CO2-TPD). The effect of thermal treatment on surface properties of the oxide spheres was also evaluated by the catalytic ethanol dehydration reaction. The hybrid method produced interesting results related to the thermal stability against sintering process and consequently low decreases of surface area. The hybrid spheres calcination at 900 and 1200 °C produced a metastable phases of alumina with a high surface area, and nanometric crystallites. Additionally, the spheres of mixed silica-alumina synthesized by this method reveal the formation of porous spheres with highly acidic OH groups, which was suggested by the catalytic performance.
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•Al and Si/Al oxide spheres with promising properties are synthesized by hybrid method.•Al2O3 spheres show high thermal stability and resistance the loss surface area.•The SiO2 addition plays an important role in the structure and porosity of the spheres.•Al2O3 and SiO2/Al2O3 spheres presented a good activity to conversion ethanol.•The activity is related to the surface area and density of OH groups on surface.