Artículos SCI

Cermets with a nominal composition (Tia(0.8)Ta(0.2)C(0.5)N(0.5)-20 wt.% Co) were synthesised by a mechanically induced self-sustaining reaction (MSR) process from stoichiometric elemental powder blends. The MSR allowed the production of a complex (Ti,Ta)(C,N) solid solution, which was the raw material used for the sintering process. The pressureless sintering process was performed at temperatures between 1400 degrees C and 1600 degrees C in an inert atmosphere. The microstructural characterisation showed a complex microstructure composed of a ceramic phase with an unusual inverse core-rim structure and a Ti-Ta-Co intermetallic phase that acted as the binder.

Catalysts of 1 wt% copper oxide supported on cerium oxide or cerium–terbium mixed oxides are comparatively examined with respect to their redox and catalytic properties for CO oxidation. Characterization of the catalysts had shown that they contain highly dispersed CuO-type entities on the corresponding nanostructured fluorite supports with copper dispersion increasing with increasing amounts of terbium in the support. In contrast, the CO oxidation catalytic activity decreases with increasing amounts of terbium in the support. On the basis of operando-DRIFTS experiments, one of the factors that could explain such behaviour is related to the greater difficulty in generating reduced copper sites active for the reaction in the presence of terbium, which in turn is evidenced to constitute an induction stage. Analysis of the redox properties is complemented by XPS which confirms the greater resistance to copper reduction in the presence of terbium.