Contact dynamics for a solid-solid reaction mediated by gas-phase oxygen
Study on the soot oxidation over ceria-based catalysts
Marco Piumetti (Politecnico di Torino)
Bart van der Linden (TU Delft - Applied Sciences, TU Delft - Applied Sciences)
Michiel Makkee (TU Delft - Applied Sciences)
Paolo Miceli (Politecnico di Torino)
Debora Fino (Politecnico di Torino)
Nunzio Russo (Politecnico di Torino)
Samir Bensaid (Politecnico di Torino)
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Abstract
Ceria-based catalysts with different topological and textural properties have been prepared to study the role of the soot-catalyst contact on the soot oxidation reaction. The physico-chemical features of the catalysts have been investigated by means of complementary techniques, such as powder XRD, N2 physisorption at -196 °C, optical microscopy at variable temperature, FESEM, TEM, and thermogravimetric analysis.As a whole, the best catalytic activity has been obtained with the CeO2-nanocubes (denoted to as "Ce-NC") because of their higher intrinsic reactivity. On the other hand, high-surface area materials prepared by the cerium nitrate decomposition (denoted to as "Ce-ND") or hydrothermal route (CeO2-stars, referred to as "Ce-SAS") resulted less effective toward the soot combustion, confirming the surface-sensitivity for this reaction.Moreover, it has been proven a higher dependence of the oxidation activity on the catalyst-to-soot ratio (wt./wt.) for the nanostructured catalyst (Ce-NC) exhibiting the lowest BET specific surface area (SBET = 4 m2 g-1). On the other hand, the accessible (real) surface area, at variance of the BET surface area, seems to play a relevant role for this solid-solid reaction mediated by gas-phase oxygen.