The catalytic activity of FeOx/ZrO2 and FeOx/sulphated-ZrO2 for the NO abatement with C3H6 in the presence of excess O2

The reducibility of FeIII to FeII in H2 increased in the order FeS/Z < Fe/ZCVD < Fe/Zi. In the C3H6 + O2 reaction, the catalytic activity for C3H6 oxidation increased in parallel with the reducibility. In the NO + C3H6 + O2 reaction, the selectivity to CO2 (rather than to CO) increased in parallel with the reducibility. By contrast, the selectivity of C3H6 towards NO rather than O2 increased in the reverse order. These results suggest that the catalytic activity and selectivity of the various samples depend on the chemical behaviour of the FeIII/FeII redox couple.