Synthesis and characterization of Pt/Fe?Zr catalysts for the CO selective oxidation

M. SCHMAL, R. SCHEUNEMANN, S. G. MARCHETTI, J. F. BENGOA.

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Año: 2011 vol. 392 p. 1 - 10

0926-860X

Catalysts of Pt on Fe2O3 and mixed oxides FexZr(1−x)O2 were prepared for the selective CO+H2 oxidation.X-ray diffraction and Mössbauer spectroscopy showed -Fe2O3 in pure support, a solid solution forx = 0.25 and mixed oxides with segregated phases for higher ?x? values. Mössbauer results showed alsothat with increasing the Zr content Zr4+ ions substitute the Fe3+ ions in the -Fe2O3 lattice, and also Fe3+ions diffusing into the zirconia lattice. The Pt/Fe0.25Zr0.75O2(p) exhibited only Fe3+ inside the ZrO2 lattice.After reduction, Fe3O4 was found in the catalysts, which decreased with increasing zirconium loading.It is interesting to note that the corresponding precursor presents 83% of Fe3+ located in the ZrO2 latticeand the remaining 17% corresponds to hematite.Catalytic tests for the preferential oxidation of CO containing H2 showed a maximum COconversion at different temperatures after reaching total oxygen conversion. The CO conversiondecreased with increasing iron content in the mixed oxide. The Pt/Fe2O3 catalyst is the mostactive compared to the other Pt/mixed oxide and Pt/ZrO2. Results showed the following order:Pt/Fe2O3(c) > Pt/Fe0.75Zr0.25O2(c) > Pt/Fe0.25Zr0.75O2(c) > Pt/ZrO2. The Pt/Fe0.25Zr0.75O2(c) presented highselectivity (56%) at 90 ◦C and is 2-fold higher compared to the Pt/Fe2O3 and Pt/ZrO2 catalyst.