Effect of Iron on the Properties of Sulfated Zirconia

A. L. COSTA PEREIRA, S. G. MARCHETTI, A. ALBORNOZ, P. REYES, M. OPORTUS, M. DO CARMO RANGEL.

APPLIED CATALYSIS A-GENERAL

Elsevier

Año: 2008 vol. 334 p. 187 - 198

0926-860X

Sulfated zirconia has found several industrial applications, mainly for catalyzing reactions which require acidic sites. In order to control the properties of this solid, the effect of iron on the sulfated zirconia properties has been studied in this work. Samples with different iron/zirconia molar ratios were prepared by the sol-gel method, followed by sulfation and characterization by several techniques. It was found that all iron ions go into the zirconia lattice when Fe/Zr¡Ü0.4, replacing the zirconium ions. However, when higher amounts of iron (Fe/Zr¡Ý0.8) are added, hematite is segregated. Different phases can be obtained depending on the iron content and the sulfur presence. Iron increases the specific surface areas of both sulfated and pure zirconia and also leads to a lower incorporation of sulfate groups as compared to pure zirconia, although it makes the solid thermically more stable. Iron also modifies the sulfated zirconia surface creating medium acidic sites. Therefore, it is possible to control the acidity of the solid doping the sulfated zirconia with iron. All these changes are very useful for catalytic applications.