engleski

Oxygen storage capacity versus catalytic activity of ceria–zirconia solid solutions in CO and HCl oxidation

CexZr1-xO2 solid solutions were prepared as a function of the composition x with constant specific surface area in order to explore the relationship between oxygen storage capacity (OSC) and activity of the oxidation reactions of CO and HCl. The as-prepared CexZr1-xO2 solid solutions were characterized by X-ray diffraction (XRD), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS). The complete (or total) oxygen storage capacity ("complete" OSC: OSCc) at 430 degrees C is shown to be linearly correlated to the CO oxidation activity at 430 degrees C as a function of the Ce concentration x, thus being compatible with the expected Mars-van-Krevelen mechanism. For the catalytic HCl oxidation reaction at 430 degrees C the activity is also shown to be linearly correlated to the OSCc with a maximum activity realized with Ce0.8Zr0.2O2. From the linear relationship of oxidation activity of HCl and OSCc (that in turn is linear to the activity of CO oxidation) we conclude that the HCl oxidation reaction over CexZr1-xO2 solid solutions proceeds via the Mars-Van-Krevelen mechanism with the reduction of CexZr1-xO2 being rate-determining.

MORPHOLOGICAL STABILITY ; OXIDES ; STORAGE/RELEASE ; NANOPARTICLES ; FUNDAMENTALS ; RELEASE ; POWDERS

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