Abstract

DAVIES, L. E.; BONINI, N. A.; LOCATELLI, S.  and  GONZO, E. E.. Characterization and catalytic activity of zirconium dioxide prepared by sol-gel. Lat. Am. appl. res. [online]. 2005, vol.35, n.1, pp.23-28. ISSN 0327-0793.

Zirconia samples prepared from Zr(n-OC₃H₇)₄ and ZrOCl₂ were characterized by XRD, BET surface area, TG-DTA, TEM/SEM, FTIR, and D₂O exchange. Oxides obtained from the alkoxide contain two types of hydroxyl groups at 3704 and 3597 cm^-1 , which do not exchange with D₂O. Those obtained from ZrOCl₂ produced three types of hydroxyl groups at 3774, 3733 and 3671 cm^-1, which do exchange with D₂O. Surface acidity was determined by FTIR of adsorbed lutidine. Only Lewis acid sites were found on samples from ZrOCl₂ hydrolysis. FTIR spectra of calcined samples exhibited strong absorption bands in the 1800 to 1000 cm^-1 region, which are ascribed to various types of carbonate and bicarbonate species. These ones are strongly adsorbed on the surface oxide and they are removed only after 3 hours at 600^oC in stream of H₂. Samples derive from the alkoxide precursor restore the original carbonate species after exposure to O₂ at 600^oC. Catalytic activity for i-propanol dehydration/dehydrogenation showed the absence of basic centers and an intermediate dehydration activity between that of silica and alumina.

Keywords : Zirconium Oxide; Zirconia; Acidity; FTIR; 2,6-Lutidine.

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