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Several bimetallic CoIr/Ce 0.82 Zr 0.18 O 2 catalysts with supports of different characteristics were studied in the oxidative steam reforming of a bio-butanol raw mixture ( n -butanol/acetone/ethanol = 6/3/1, mass ratio). Ce 0.82 Zr 0.18 O 2 supports were prepared by precipitation and then calcination at different temperatures (500 °C, 700 °C and 900 °C). The calcination temperature of the support determined certain characteristics of the final catalyst, namely: BET surface area, crystallite size, basicity, reduction properties and oxygen storage capacity (OSC). All of these factors were found to affect the performance of the catalysts in terms of: raw mixture conversion, hydrogen selectivity and resistance to deactivation upon long-term testing. Several techniques such as XRD, TPR, CO 2 TPD, CO 2 adsorption calorimetry, Raman, DRIFT, TEM, XPS and OSC were used to characterize the catalysts. Characterization of samples before and after catalytic tests allowed us to determine the influence of the catalyst characteristics on the deactivation process.

The influence of the addition of a noble metal (Ru, Rh, Ir or Pd) on the catalytic performance of Co/ZnO was studied with respect to oxidative steam reforming of the bio-butanol raw mixture (butanol/acetone/ethanol = 6/3/1, mass ratio). Bimetallic catalysts, CoM/ZnO (M = Ru, Rh, Ir, Pd) had higher conversion values, decreased deactivation and higher H2 concentration in the outlet gas than monometallic Co/ZnO. However, significant differences were found in both raw mixture conversion and H2 concentrations for the different CoM/ZnO, depending on M. CoRh/ZnO presented the best catalytic behavior (65.1 mol% hydrogen in the outlet after 100 h of reaction at 500 °C with 84% conversion). Characterization of catalysts post-reaction by Raman spectroscopy and TPO showed that less ordered and less abundant carbonaceous deposits were formed over bimetallic catalysts than over the monometallic one; CoRh/ZnO had the lowest amount of such coke.

The ethanol steam-reforming reaction was studied over ZnO-supported cobalt catalysts (10 wt.% Co). Catalysts were prepared by impregnation of nitrate and carbonyl cobalt precursors. Characterization was accomplished by transmission electron microscopy (TEM), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), and in situ techniques: magnetic measurements, and diffuse reflectance infrared spectroscopy (DRIFT) coupled to mass spectrometry. The use of Co 2 (CO) 8 as precursor produced a catalyst that was highly stable and selective for the production of CO-free hydrogen at reaction temperature as low as 623 K. The only by-product was methane and selectivity of 73% to H 2 and 25% to CO 2 was obtained. Under reaction conditions, the catalyst showed 92% of reduced cobalt, mainly as small particles.

This study reports new gallium-promoted copper-based catalysts prepared by co-impregnation of methoxide–acetylacetonate (acac) precursors from methanolic solutions onto silica and zinc oxide supports. Catalyst performance in the CO2 hydrogenation to methanol was investigated at 2 MPa and temperatures between 523 and 543 K. A high activity and selectivity for ZnO-supported catalysts was found, which also showed a high stability in terms of both activity and selectivity. The maximum value for the activity was 378 g MeOH/kg cat h at 543 K, with a selectivity of 88% towards methanol production. The high performance of these materials in the CO2 hydrogenation is related to the presence of Ga2O3 promoter and highly dispersed Cu+ species on the surface, determined by XPS and Auger on used catalysts.

In this study, gallium-promoted copper-based catalysts prepared by impregnation methods on silica and ZnO supports, were examined for the hydrogenation of CO 2 to methanol. The surface characteristics of catalysts depended on the support and were related to their catalytic performance. Silica-supported catalysts tested at reaction temperatures between 523 and 543 K were highly selective and stable. The selectivity to methanol was around 99%, the conversion to CO was very low and negligible amounts of hydrocarbons were formed. The use of hydrophobic silica enhanced the performance of the catalyst in terms of activity, selectivity and stability. The modification of properties of copper particles is related to the presence of very small particles of Ga 2 O 3 on the surface.