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One of the main issues for the catalytic abatement of methane from natural gas fueled vehicles over Pd-based materials is due to the large amount of water vapor in the exhausts, which can severely deactivate the catalyst. In this work, we investigated the effect of water added during methane oxidation on a series of silica doped Pd/ceria catalysts prepared by solution combustion synthesis, using different characterization techniques. The results obtained by coupling Temperature Programmed Oxidation (TPO) experiments and High Resolution Transmission Electron Microscopy (HRTEM) indicate that the mechanism of PdO-Pd-PdO phase transformation over Si-doped catalysts is different in dry and wet conditions. The presence of water not only shifts the onset of PdO decomposition to higher temperature, but also PdO-Pd transition is found to proceed via the formation of multi-domain PdO/Pd particles. This effect is tentatively attributed to the suppression of oxygen exchange induced by the presence of stable hydroxyl groups on silica.

Binder-free ceria pastes have been formulated and used to prepare ceria structures with a woodpile arrangement of microchannels through 3D printing. After loading them with nickel, these catalytic structures have been tested for ammonia decomposition to obtain hydrogen, and their performance has been compared with those of conventional Ni/CeO2 powder catalysts and with that of a conventional cordierite honeycomb washcoated with Ni/CeO2. Samples have been characterized by N2 physisorption, inductively coupled plasma optical emission spectrometry (ICP-OES), X-Ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. At the same reaction temperature and flow rate to catalyst weight ratio (F/W), the 3D-printed ceria structures show a catalytic activity much higher than that of the cordierite honeycomb on a reactor volume basis. Additive manufacturing represents a valuable tool to prepare customized ceria-based catalytic structures for practical application with a variety of geometries not attainable with conventional methods.

PdCu bimetallic catalysts supported on alumina were prepared by different common impregnation protocols and by a polyol nanoparticles synthesis route. These materials were studied in order to establish the relationship between structure, particle size, Pd–Cu interaction and catalytic activity/selectivity in the hydrodechlorination of trichloroethylene (TCE) in gas phase. The surface properties and the interaction between Cu and Pd in the bimetallic particles, as well as their catalytic behaviour are strongly influenced by the preparation protocol. Depending on the synthesis, PdCu alloy formation or isolated phases were observed. The presence of isolated Pd particles leads to high ethane selectivity, whereas upon alloy formation or strong interaction between Pd and Cu a higher ethylene yield was obtained. By the nanoparticles polyol synthesis, Pd-Cu alloy formation was obtained, leading to total selectivity to ethylene in the TCE hydrodechlorination reaction. On the Pd monometallic catalysts larger particle size resulted in higher levels of ethylene formation.

Various supported cobalt catalysts (Co/MgO, Co/Al2O3, Co/SiO2, Co/TiO2, Co/V2O5, Co/ZnO, Co/La2O3, Co/CeO2 and Co/Sm2O3), were characterised by magnetic measurements under ethanol steam-reforming conditions, in situ diffuse reflectance infrared spectroscopy and UV-Vis-NIR diffuse reflectance spectroscopy. Their magnetic behaviour was analysed as a function of reaction temperature and hydrogen treatment and was related to the cobalt species in the catalysts and to their catalytic behaviour in the steam-reforming of ethanol. The catalysts were prepared from Co2(CO)8 and used without previous calcination or reduction. All samples showed a paramagnetic or diamagnetic behaviour before reaction. The catalysts that performed well in the steam-reforming of ethanol presented under reaction conditions, metallic (ferromagnetic) cobalt particles and oxidised cobalt species. An easy exchange between small metallic cobalt particles (produced under H2 or under ethanol steam-reforming conditions) and oxidised cobalt species (produced under ethanol steam-reforming conditions) was found in these catalysts.

Magnesia-supported platinum–tin catalysts with a Pt content 0.25–3% and atomic ratio Pt/Sn = 1 were prepared from a Pt–Sn bimetallic complex. Characterization of catalysts by XRD, TEM, EDX, XPS and CO singleton frequency indicated the formation of well-dispersed bimetallic particles, the size of which decreased with the metal content. Both dilution and electronic effects on Pt by Sn were evidenced by IR experiments of CO adsorption. The behavior of catalysts in isobutane dehydrogenation at 753 K and atmospheric pressure was related to their structural characteristics and compared to silica- and alumina-supported catalysts prepared by a similar method, and to the respective monometallic catalysts. Magnesia-supported bimetallic catalysts were the most selective to isobutene production. Selectivities higher than 99% were achieved for conversion values of 11%.

The preparation of a CeO2ZrO2 mixed oxide of composition Ce0.8Zr0.2O2 with its characterization and its use as a catalyst in the oxidation of isobutane is reported, and compared with the reactivity of pure CeO2. The formation of an homogeneous, fluorite-type solid solution is observed; the material is characterized by a higher reducibility and a higher capacity of oxygen uptake compared to pure CeO2. The catalytic activity in the oxidation of isobutane is not greatly affected by the introduction of ZrO2, but the selectivity to isobutene is significantly enhanced. This enhancement has been attributed to an increased oxygen mobility and to an increased activity for the Ce4+/Ce3+ redox couple, occurring as a consequence of the creation of surface and bulk defects in the solid solution, induced by the introduction of the smaller Zr4+ cation in the fluorite lattice.