Investigations into nanostructured ceria–zirconia catalysts for soot combustion

摘要: Abstract A set of nanostructured ceria–zirconia catalysts with different Zr-contents and structural features has been prepared to study the effect both Zr-amount its surface-dependent activity towards soot combustion under experimental conditions (namely in “loose” “tight” soot-catalyst contact). sample synthesized by means solution synthesis (SCS) for comparison purposes. The physico-chemical properties have investigated using complementary techniques. best catalytic performances achieved Ce0.9Zr0.1O2–NP catalyst (where NP nano-polyhedra 0.9 indicates atomic ratio Ce/Ce + Zr), due higher mobility lattice oxygen within solid, easier reducibility, compared high-surface area same Ce/Zr ratio. Moreover, better activities, terms conversions, reached Ce0.9Zr0.1O2–NP, than similar Zr-amounts (denoted as CexZr1−xO2–NP, where x = 0.8 or 0.7). substitution some Ce4+ Zr4+ ions favors formation defects (i.e., vacancies) ceria lattice, thus inducing a distortion sublattice. However, amount redox Ce species decreases Zr-content increases. It therefore seems that incorporation into does not direct beneficial on oxidation calcined at low/mild temperatures, since it population surface redox-active centers, which depend directly density Ce3+–Ce4+ species. On other hand, lower conversion values mesoporous (Ce0.9Zr0.1O2–M) microporous (50-Ce0.9Zr0.1O2–NP/FAU) samples comparative (Ce0.9Zr0.1O2–SCS) exhibited worse activities porous materials, confirming key role textural this reaction.