CO oxidation over nonstoichiometric nickel manganite spinels

Nonstoichiometric nickel–manganese spinel oxides, NixMn3−x ▭3δ/4O4+δ (1≥x≥0), have been synthesized by calcination in air of mixed oxalates at 623 K. These materials are shown to be highly reactive for CO oxidation, some conversion being observed at room temperature for the most active solid (x=1.0). The interaction of CO and O2 with these oxides has been studied by in situ IR spectroscopy under steady-state and transient reaction conditions. A detailed mechanism is proposed wherein CO reacts with coordinatively unsaturated cations to give carbonyl complexes which in turn react with surface oxygen activated on anionic vacancies. Adsorbed and gaseous CO2 also undergo much slower side reactions with lattice oxygen or surface hydroxide groups to give more stable hydrogen carbonate and carbonates species, which lead to catalyst deactivation. Marked effects of pretreatment are explained on the basis of the observed kinetics and the proposed mechanis

Catalytic conversion of biomass: ethanol reforming and pyrolytic bio-oils co-cracking. Coupling between reactivity, diffusion and ageing for heterogeneous catalysts

SSCI-VIDE+ING+CMIInternational audienceNon

Les bio-carburants sont-ils tous durables et écologiques pour l’avenir de nos sociétés ?

SSCI-VIDE+ING+CMIInternational audienceCarburants/Biocarburants, Durables, ou peu, ou pasÉcologiques, ou peu, ou pasEconomie «zéro déchets», circulaire, recyclage, …Questions récurrentes, d’actualité, trop ou insuffisamment documentées, ..?Quelles frontières entre les domaines scientifiques, sociétaux, politiques?La société (les citoyens) peut-elle infléchir les orientations de la recherche scientifique? De quelle manière